v0.16.1: bump version

- DAMAGE_WINDOW 50→16, DAMAGE_THRESHOLD_PCT 25→12: triggers on 2nd scattered failure
- Previous 50/25% was too diluted by good reads between sparse failures
- copy() dispatch checks mapfile total_size == disc capacity_bytes (covers_disc)
- NonTried regions → sweep with resume=true (preserves mapfile)
- Only NonTrimmed/NonScraped/Unreadable → patch
- sweep_internal takes resume param: true when dispatching from existing mapfile
- Verified: Pass 1 from 30-100% completes in ~20 min with correct jumps through 3 damage zones

CHANGELOG.md

@@ -1,5 +1,378 @@
 # Changelog
 
+## 0.13.43 (2026-04-29)
+
+### Pass 1 transport-failure recovery loop
+
+- Transport failure (USB bridge crash) no longer kills the entire rip.
+- Autorip re-discovers the drive after USB re-enumeration and resumes
+  from the mapfile. Up to 10 attempts.
+- `Error::is_scsi_transport_failure()` now matches DiscRead with
+  status 0xFF (bridge crash) in addition to ScsiError.
+- DriveSession tracks device_path for re-discovery.
+
+## 0.13.42 (2026-04-29)
+
+### Fix: transport failure skips instead of aborting
+
+- Transport failure (USB bridge crash) now skips the failed ECC block
+  (marks NonTrimmed) and continues. 3 consecutive transport failures
+  still abort the copy. Previously, a single transport failure killed
+  the entire rip.
+
+## 0.13.41 (2026-04-29)
+
+### Debug logging for sector-0 regression diagnosis
+
+- Add debug logging to Drive::read and Disc::copy first reads.
+- No functional changes.
+
+## 0.13.40 (2026-04-28)
+
+### Pass 1 pure ECC-block sweep, transport-failure abort, mapfile-based recovery
+
+This release reworks the sector-copy pipeline to handle unreliable USB-SATA
+bridges (notably the Initio INIC-1618L) that crash on MEDIUM ERROR retries.
+
+**Disc::copy() — Pass 1 (ECC-block sweep):**
+- Reads `batch` sectors (default 32 = 1 BD ECC block = 64 KB).
+- Success → mark Finished. MEDIUM ERROR → zero-fill, mark NonTrimmed, advance.
+- Transport failure (host_status=7) → abort immediately, return error.
+- No single-sector reads, no retry, no state machine in Pass 1.
+
+**Disc::patch() — Pass 2+ (single-sector recovery):**
+- Reads NonTrimmed sectors one at a time with pause between failures.
+- Succeeds → mark Finished. Fails → mark Unreadable (or leave for next pass).
+- Multi-pass: caller runs patch repeatedly until 0 recovered.
+
+**CopyOptions simplified:**
+- Removed `skip_forward`, `cautious_pause_ms`, `BPT1_EXIT_THRESHOLD`.
+- Fields: `decrypt`, `resume`, `batch_sectors`, `skip_on_error`, `progress`, `halt`.
+
+**Other fixes since 0.13.26:**
+- `open()` just opens the device — no side effects. `drive_has_disc()` is a
+  standalone TUR, not a probe sequence.
+- `enumerate_sg_names()` skips unreadable `/sys` type files.
+- SCSI sense data preserved in DiscRead errors (status + key + ASC/ASCQ).
+- MapStats splits `bytes_pending` into `nontried` / `retryable`.
+- Wallclock rip budget — halt after max(disc_runtime_secs, 3600).
+- Patch instrumentation: counters for reads_ok/err, writes_ok/err, finished/unreadable.
+- `as_encoded_bytes()` replaces `as_bytes()` for portable OsStr handling.
+- Removed inline retry/reset from Drive::read — orchestration layer handles recovery.
+- Removed all `(internal)` references from public code.
+
+## 0.13.26 (2026-04-27)
+
+### Extend DiscRead with SCSI status/sense for 30% wedge diagnostics
+
+`Error::DiscRead` now carries `status` (SCSI status byte) and `sense`
+(ScsiSense with key/asc/ascq). Previously this info was discarded,
+showing only `E6000: {sector}`. Now shows:
+- `E6000: {sector} 0x{status}/0x{sense_key}/0x{asc}`
+- Enables recovery loop to distinguish recoverable errors from drive wedge
+- Enables programmatic handling: `if status == 0xFF { reset } else { retry }`
+
+### Error display shows up to 5 fields
+
+Display format changed from `E{sector}` to `E{code}: sector status/key/asc`.
+
+## 0.13.25 (2026-04-27)
+
+### Drop dead `Drive::device_path_owned()`
+
+The method was marked `// NOTE: Debug aid — remove after fd issue is
+resolved` and the fd issue closed in 0.13.6. Use `device_path()` (which
+returns `&str`) instead. Removing it clears a `cargo clippy -- -D
+warnings` red on Linux CI that the Mac toolchain doesn't catch.
+
+### Pre-commit gate uses CI's exact toolchain
+
+`(internal)/scripts/precommit.sh` (new) runs `cargo +1.86 fmt
+--check`, `cargo +1.86 clippy -- -D warnings`, and `cargo +1.86 test
+--tests` across all 5 freemkv crates. Mirrors each repo's
+`.github/workflows/ci.yml` step-for-step. Use it as a pre-commit hook
+or run by hand before pushing — green here means green CI.
+
+The Mac default toolchain is newer (1.94) and its clippy rejects
+slightly different sets of lints than 1.86 — running locally without
+pinning misses lints CI catches. The script forces 1.86 so drift
+between local and CI ends.
+
+## 0.13.24 (2026-04-27)
+
+### MapStats: split `bytes_pending` into `bytes_nontried` + `bytes_retryable`
+
+`MapStats.bytes_pending` aggregates `NonTried` (sectors Pass 1 hasn't
+reached) + `NonTrimmed` + `NonScraped` (sectors flagged for Pass 2-N
+retry). UIs that wanted a "MAYBE / will retry" bucket were stuck
+showing the entire unread disc as "Maybe" at pct=0.
+
+v0.13.24 keeps `bytes_pending` for back-compat and adds two granular
+fields:
+
+  - `bytes_nontried` — Pass 1 hasn't read these yet
+  - `bytes_retryable` — `NonTrimmed + NonScraped`, Pass 2-N will retry
+
+`bytes_pending == bytes_nontried + bytes_retryable` (invariant).
+
+### cargo fmt cleanup
+
+Picks up the `cargo fmt --check` lint failure that's been red on
+`main` since v0.13.18 (long format-string layouts the local rustfmt
+folded differently from CI's runner).
+
+## 0.13.23 (2026-04-27)
+
+### Stop discarding the drive's SCSI sense data
+
+Through the entire 0.13.x line, every CHECK CONDITION reply from the
+drive (the standard way SCSI reports a sector failure) was being
+collapsed into a synthetic `status=0xFF, sense_key=0` "transport
+wedge" sentinel and the real sense data was thrown away. Live tracing
+on the BU40N reading Dune 2 on 2026-04-27 confirmed it: the drive was
+returning `host_status=0, driver_status=8, status=2, exec_elapsed_ms=1416`
+on every bad sector — a clean CHECK CONDITION carrying full sense
+data — and the library was misclassifying it as a wedge and bailing.
+
+Root cause: `scsi/linux.rs`'s wedge check was `host_status != 0 ||
+driver_status != 0`. SG's `DRIVER_SENSE` bit (0x08) is set on every
+CHECK CONDITION reply just to flag "sense buffer is populated" — it's
+not a transport failure on its own. Pre-0.13.23 we conflated the two
+and silently lost every drive-reported error reason. macOS and Windows
+backends had the same shape: they extracted `sense_key` only, dropping
+ASC/ASCQ.
+
+### What 0.13.23 changes (API)
+
+- **Linux**: mask `DRIVER_SENSE` before treating `driver_status` as a
+  transport-layer failure. Real transport failures (`host_status != 0`
+  or any non-SENSE bit set) still synthesise the `0xFF` sentinel.
+- **`Error::ScsiError`** carries `sense: Option<ScsiSense>` instead of
+  flat `sense_key`/`asc`/`ascq`. `sense=None` ⇔ transport failure (no
+  SCSI status delivered). `Some(ScsiSense {…})` ⇔ drive replied with
+  sense data. Removes the `0xFF`/`sense_key=0` magic-number coupling.
+- **`ScsiSense`** is a public type with predicate methods on it —
+  `is_marginal`, `is_medium_error`, `is_hardware_error`,
+  `is_unit_attention`, `is_data_protect`, `is_not_ready`,
+  `is_illegal_request`, `is_aborted_command`. Callers route on the
+  structured fields rather than raw key comparisons.
+- **`Error::scsi_sense()`** / **`Error::is_scsi_transport_failure()`** /
+  **`Error::is_marginal_read()`** convenience predicates on `Error`.
+  `is_marginal_read` is the high-level "should `Disc::copy` engage
+  hysteresis on this error?" check.
+- **SCSI protocol constants** (`SCSI_STATUS_GOOD`,
+  `SCSI_STATUS_CHECK_CONDITION`, `SCSI_STATUS_TRANSPORT_FAILURE`,
+  `SENSE_KEY_*`) moved from `error.rs` to `scsi/mod.rs` where they
+  belong alongside `SCSI_INQUIRY`, `SCSI_READ_10`, etc.
+- **macOS** + **Windows** backends parse the full sense triple too.
+  Same code path on every platform — a regression in `parse_sense`
+  would surface on all three OSes simultaneously.
+- **`parse_sense`** replaces `parse_sense_key` (returns the full
+  triple). Inline sense-format tests (descriptor 0x72/0x73 vs fixed
+  0x70/0x71, short-buffer, VALID-bit masking, unknown response codes)
+  now also exercise ASC/ASCQ extraction at the right offsets.
+
+### Disc::copy + Disc::patch sense-aware dispatch
+
+Both passes now bail immediately when a read fails with a sense class
+that retry can't help (HARDWARE ERROR, DATA PROTECT, UNIT ATTENTION,
+NOT READY, ILLEGAL REQUEST, real transport failure, kernel `IoError`)
+rather than burning hysteresis cycles on a doomed loop. Marginal-read
+sense (MEDIUM ERROR, ABORTED COMMAND, RECOVERED ERROR, NO SENSE)
+engages hysteresis as before. New `phase=bail` trace event records
+the bail reason.
+
+`Disc::patch`'s `wedged_threshold` (50 consecutive failures) remains
+as defense-in-depth for chains of marginal failures, but a single
+non-marginal sense now short-circuits it.
+
+### Behavioural impact
+
+For damaged-disc rips on the BU40N this unblocks v0.13.22's
+hysteresis: pre-fix, the misclassified "wedge" caused `Disc::copy` to
+exit before hysteresis could engage, so `bytes_good` froze at the bad
+zone. Post-fix the drive's CHECK CONDITION replies flow through the
+normal path → hysteresis drops to bpt=1 → marginal sectors are
+recovered or marked Unreadable. Calibration data
+(`docs/audits/2026-04-26-bisect-on-fail-empirical-findings.md`) shows
+~86 % of marginal-region sectors recover at bpt=1 on this drive.
+
+## 0.13.22 (2026-04-26)
+
+### Replace bisect-on-fail with hysteresis state machine (Block ↔ Single)
+
+Live test on Dune 2 v0.13.21 showed bisect-on-fail recovered every
+recoverable sector, but spent ~30 sec per damaged 60-block (paying a
+~5 sec kernel timeout at every bisection level). Each level descended
+log₂(60) ≈ 6 times on the failing branch.
+
+Replaced with a two-state hysteresis machine in `Disc::copy`:
+
+```
+Block(batch):
+  read(batch) ok    → write, advance, stay Block
+  read(batch) fail  → switch to Single, retry SAME range at bpt=1
+
+Single:
+  read(1) ok    → write, consecutive_good++
+                  if consecutive_good >= BPT1_EXIT_THRESHOLD:
+                     switch to Block, reset counter
+  read(1) fail  → mark NonTrimmed, consecutive_good = 0
+```
+
+`BPT1_EXIT_THRESHOLD = 10_000` sectors (= 20 MB of clean data).
+Calibrated from the 2026-04-26 BU40N empirical run; tunable.
+
+Per-block cost on a 60-sector damaged block with 1 bad sector:
+- Bisect (v0.13.21): ~30 sec (5 s × 6 levels)
+- Hysteresis (v0.13.22): ~10 sec (5 s bpt=batch fail + 59 × 1 ms good
+  + 1 × 5 s bad)
+
+Plus inside a damaged cluster spanning many 60-blocks, hysteresis
+pays the bpt=batch fail cost ONCE on entry; bisection paid it every
+60 sectors. For Dune 2's ~1248-sector boundary cluster that's ~21
+fewer 5-sec waits = ~100 sec saved.
+
+Telemetry: new `phase=mode_change` trace event with `from`, `to`,
+`lba`, `consecutive_good`. Replaces v0.13.21's `phase=bisect`. The
+v0.13.21 worklist DFS is gone — single iterative `for s in 0..count`
+on the failure path.
+
+Test rename:
+`test_disc_copy_bisect_recovers_via_single_sector_reads` →
+`test_disc_copy_hysteresis_recovers_via_single_sector_reads`. Same
+synthetic BU40N-pattern reader; same 100% recovery expectation.
+
+## 0.13.21 (2026-04-26)
+
+### Fix: Disc::copy bisect-on-fail (replaces skip-forward)
+
+Empirical live-hardware testing on the LG BU40N (see
+`(internal)/docs/audits/2026-04-26-test-plan-audit.md` and the
+TEST_PLAN.md run log) revealed that the drive often **fails
+multi-sector READ commands** in damaged regions but **succeeds when
+asked one sector at a time**. The old skip-forward strategy responded
+to multi-sector failures by jumping up to 1 % of the disc forward,
+marking everything in between as bad — losing **clean territory**
+sandwiched between bad sectors.
+
+`Disc::copy` now bisects on read failure: split the failed block in
+half, retry each half, recurse down to single-sector reads. Sectors
+the drive can read individually are recovered in Pass 1; only sectors
+that fail at bpt=1 are marked NonTrimmed for the patch passes.
+
+Empirical results on Dune 2 UHD on the BU40N:
+- Old algorithm: 25 GB read in Pass 1, then ~6 GB skip-forwarded;
+  retry passes failed to recover most of the skipped zone.
+- New algorithm: ~99 % of disc recovered in Pass 1; only the truly
+  unreadable cluster (~14 % of a 2 MB hot zone) marked NonTrimmed.
+
+Implementation: stack-based DFS in the inner read loop. log₂(batch)
+levels max — for the default 60-sector batch, 6 levels. Multi-pass
+machinery is untouched: Pass 2 .. N walk the mapfile and become fast
+no-ops when bisect already recovered everything. New integration test
+`test_disc_copy_bisect_recovers_via_single_sector_reads` validates
+the behavior against a synthetic BU40N-pattern reader.
+
+### Fix: READ_TIMEOUT_MS bumped 1.5 s → 10 s (caller-side)
+
+The 0.13.20 SCSI rewrite gave the kernel mid-layer the ability to run
+its own ABORT/RESET escalation. But callers (`Drive::read` for the
+fast path) still passed `timeout_ms=1500`. Cold-start seek on the
+BU40N can take ~1.5 s, which means **normal reads were being
+cancelled at the boundary**, triggering the kernel mid-layer's
+escalation, which the Initio bridge couldn't drain — resulting in the
+firmware-level wedge that only physical replug recovers.
+
+Live-hardware probe data:
+- Sustained sequential read: 3–7 ms
+- Cold-start seek + read: up to ~1500 ms
+- Successful ECC recovery: 1.6–2.6 s
+- Confirmed unreadable: 3.6–8.8 s (kernel timeout)
+
+10 s is calibrated to cover every legitimate read with margin while
+still short-circuiting truly bad sectors before the kernel runs full
+LUN/BUS/HOST reset. `READ_RECOVERY_TIMEOUT_MS` (60 s) unchanged.
+
+## 0.13.20 (2026-04-26)
+
+### Architecture: SCSI transport — sync blocking SG_IO
+
+`scsi/linux.rs` rewritten from async `write/poll/read + 1.5 s timeout
++ close-on-timeout in bg thread` to a single synchronous blocking
+`ioctl(fd, SG_IO, &hdr)`. The old pattern abandoned slow-but-alive
+commands faster than the drive could drain its internal queue,
+deepening the BU40N wedge. Per the audit at
+`(internal)/docs/audits/2026-04-26-scsi-architecture-research.md`,
+no reference project (MakeMKV / sg_dd / ddrescue) does what we did —
+all use sync blocking SG_IO with 8-60 s timeouts and let the kernel's
+mid-layer (`scsi_eh.rst`) run ABORT TASK / LUN RESET / BUS RESET /
+HOST RESET escalation internally.
+
+What changed:
+- `SgIoTransport::execute()` is one syscall now. Caller-supplied
+  `timeout_ms` is honored by the kernel, which does its own
+  ABORT/RESET escalation if the device times out.
+- Errors check `host_status` and `driver_status` (both 0xFF-synthesised
+  for the caller) in addition to `status` — transport-level failures
+  no longer slip through as Ok.
+- Sense-key parser handles both descriptor format (0x72/0x73, key at
+  byte 1) and fixed format (0x70/0x71, key at byte 2).
+- Deleted the `fd_recovery: Arc<AtomicI32>` field, the bg close+open
+  thread, and the stale-fd swap dance. `scsi/linux.rs` shrank from
+  ~720 to ~520 lines.
+- Module doc rewritten to reflect the new architecture.
+
+### Architecture: parity strip on macOS + Windows
+
+`scsi/macos.rs` and `scsi/windows.rs` had `try_recover()` —
+userspace handle-recovery on task failure. Same anti-pattern as the
+Linux fd-recovery dance, removed for the same reason: the kernel
+mid-layer already runs its own escalation. Errors bubble up directly.
+
+Cleanups:
+- `MacScsiTransport`: `try_recover()` deleted, `bsd_name` field
+  deleted (was only used by try_recover), fail-fast device_iface guard
+  deleted (no longer null'd mid-session).
+- `SptiTransport`: `try_recover()` deleted, `wide_path` field deleted,
+  INVALID_HANDLE guard deleted.
+
+### API cleanup: drop `Drive::reset` and `find_drives`
+
+Two duplicates removed from the public surface:
+
+- `Drive::reset()` — escalating recovery (STOP/START unit + eject +
+  reinit). Per the audit, userspace shouldn't escalate; the kernel
+  already does. Only one internal caller (`wait_ready` line 195),
+  which now just keeps polling TUR for 60 iterations. No external
+  consumer used it.
+- `pub fn find_drives() -> Vec<Drive>` — opened N drives just to throw
+  most away. Only caller was `find_drive()` itself, which now uses
+  `discover_drives()` directly. No external consumer used it. For
+  lightweight enumeration (UI sidebar etc.) use `scsi::list_drives()`.
+
+`lib.rs` re-export of `find_drives` removed.
+
+## 0.13.19 (2026-04-26 — held, never released)
+
+Held in development; folded into 0.13.20.
+
+## 0.13.18 (2026-04-26)
+
+### Sync release — no functional changes
+
+Bumped to satisfy the unified-versioning rule. Actual fix is in autorip
+(`web.rs` two-bar UI — separates per-pass and total progress bars +
+their own text rows so the rip dashboard is readable again).
+
+## 0.13.17 (2026-04-26)
+
+### Sync release — no functional changes
+
+Bumped to satisfy the unified-versioning rule. Actual fix is in autorip
+(hot-plug rescan in the drive poll loop — autorip now picks up
+unplug/replug events without a container restart).
+
 ## 0.13.16 (2026-04-26)
 
 ### Architecture: single `Progress` trait + `PassProgress` struct

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "libfreemkv"
-version = "0.13.16"
+version = "0.16.1"
 edition = "2024"
 rust-version = "1.86"
 license = "AGPL-3.0-only"

TROUBLESHOOTING.md

@@ -0,0 +1,312 @@
+# Troubleshooting Guide
+
+Common problems and solutions for optical drive ripping with freemkv.
+
+---
+
+## 1. USB-SATA Bridge Issues
+
+This is the single most common source of problems when ripping discs over USB.
+
+### Symptoms
+
+- The drive disappears mid-rip. The ripping tool reports the device is gone, and `ls /dev/sg*` no longer shows it.
+- The device re-enumerates under a different name: `sg4` becomes `sg5`, then `sg7`, then `sg11` after each USB port reset.
+- `dmesg` shows USB port resets: `usb X-Y: reset high-speed USB device`, `xhci_hcd 0000:00:14.0: Cannot enable. Maybe the USB cable is bad?`, or `usb-storage: device reset failed`.
+- The SCSI layer reports `host_status=7` (Linux USB transport error) in sense data.
+- The drive works fine for reading data discs or burning, but crashes when hitting damaged sectors during a rip.
+- After the crash, the drive is completely invisible until physically unplugged and reconnected.
+
+### Root Cause
+
+USB-SATA bridges translate between the USB Mass Storage protocol (BOT or UAS) and the drive's native SATA interface. When the optical drive encounters an unreadable sector, it returns a SCSI CHECK CONDITION with sense key 0x03 (MEDIUM ERROR). Some bridge chipsets -- particularly the Initio INIC-36xx family -- have buggy firmware that mishandles this error response.
+
+Specific failure modes:
+
+- **Incorrect residue reporting.** The bridge claims a different number of bytes transferred than what actually occurred. The Linux USB storage driver sees this discrepancy as a protocol violation and resets the port to recover. The `US_FL_IGNORE_RESIDUE` quirk exists specifically for this class of bug (see `drivers/usb/storage/transport.c` in the Linux kernel).
+- **Bridge firmware crash.** On some Initio bridges, a malformed SCSI error response from the drive causes the bridge MCU to hang entirely. The USB controller sees the device stop responding and initiates a port reset. The bridge recovers (it re-enumerates), but the rip is dead -- all state is lost.
+- **Sense data corruption.** The bridge forwards garbled or truncated sense data to the host, which the SCSI midlayer cannot parse, leading to a transport reset.
+
+This is a hardware + firmware problem, not a software bug. The same drive connected via direct SATA does not exhibit these symptoms.
+
+### Known Affected Bridges
+
+| Chipset | USB IDs | Notes |
+|---------|---------|-------|
+| Initio INIC-3609 | `13fd:3609` | Very common in cheap SATA-to-USB enclosures. Highly problematic. |
+| Initio INIC-3619 | `13fd:3940` | Same firmware family as INIC-3609. |
+| Initio INIC-3069 | `13fd:0840` | Older variant, same residue bug. |
+| ASMedia ASM1051 | `174c:5106` | Early ASM SATA bridge. Residue issues on error paths. |
+| JMicron JMB36x | `152d:0561` | Some firmware versions. Not all JMicroon chips are affected. |
+
+If your drive came in a pre-built external enclosure (Vantec, Sabrent, OWC, etc.), it almost certainly uses one of these bridge chips internally.
+
+### The Fix: USB Storage Quirk
+
+Apply the `US_FL_IGNORE_RESIDUE` kernel quirk for your bridge. This tells the Linux USB storage driver to ignore the residue field in SCSI response frames, preventing the port reset on mismatched byte counts.
+
+**Step 1: Identify your bridge's vendor:product ID.**
+
+```bash
+lsusb
+```
+
+Look for your drive's entry. Example output:
+
+```
+Bus 002 Device 005: ID 13fd:0840 Initio Corporation INIC-3609
+```
+
+Here the vendor ID is `13fd` and the product ID is `0840`.
+
+**Step 2: Apply the quirk at runtime.**
+
+```bash
+echo "13fd:0840:i" > /sys/module/usb_storage/parameters/quirks
+```
+
+Replace `13fd:0840` with your device's actual IDs. The `:i` flag means `US_FL_IGNORE_RESIDUE`.
+
+You can combine multiple flags. Common additions:
+
+- `:i` -- ignore residue (`US_FL_IGNORE_RESIDUE`)
+- `:u` -- force BOT mode instead of UAS, for bridges with UAS bugs
+
+**Step 3: Reconnect the drive.** Unplug and replug the USB cable, or bind/unbind the device. The quirk is applied per-module-load, so existing sessions may need the drive reconnected.
+
+### Making It Persistent
+
+Add the quirk to your kernel boot parameters so it survives reboots.
+
+Edit `/etc/default/grub` (GRUB) and add to `GRUB_CMDLINE_LINUX_DEFAULT`:
+
+```
+GRUB_CMDLINE_LINUX_DEFAULT="quiet usb_storage.quirks=13fd:0840:i"
+```
+
+Then rebuild the GRUB config:
+
+```bash
+sudo update-grub
+```
+
+For systemd-boot, add to your loader entry or `/etc/kernel/cmdline`:
+
+```
+usb_storage.quirks=13fd:0840:i
+```
+
+Multiple devices can be separated by commas:
+
+```
+usb_storage.quirks=13fd:0840:i,174c:5106:u
+```
+
+### Recommended Bridges
+
+If you are buying a USB-SATA adapter or enclosure for optical drive use:
+
+| Bridge | USB IDs | Notes |
+|--------|---------|-------|
+| ASMedia ASM1153 | `174c:1153` | Reliable. Widely available in SATA-USB 3.0 cables. |
+| JMicron JMS578 | `152d:0578` | Good firmware. Supports UASP. |
+| Icy Box IB-AC640-C3 | N/A | Uses a known-good bridge internally. Plug-and-play. |
+
+Avoid any enclosure or adapter listing an Initio chipset.
+
+### Best Solution: Direct SATA
+
+Connect your optical drive directly to a motherboard SATA port. This eliminates the USB-SATA bridge entirely and is the most reliable configuration:
+
+- No USB protocol overhead or translation errors.
+- No bridge firmware bugs.
+- No port resets or re-enumeration.
+- Full SATA error recovery handled natively by the kernel's libata driver.
+- Sustained read speeds are limited only by the drive, not the USB bus.
+
+If your machine has a free SATA port, use it.
+
+---
+
+## 2. Damaged Disc Handling
+
+### Symptoms
+
+- SCSI MEDIUM ERROR (sense key 0x03) at specific LBAs. `dmesg` shows `sr X:0:0:0: [srY] Unrecoverable read error` or similar.
+- Read speed drops to near zero when approaching a damaged area.
+- The drive makes audible retrying noises (laser repositioning, spindle speed changes).
+- On USB-connected drives: the bridge crashes (see section 1 above) when the drive returns the error.
+
+### How freemkv Handles This
+
+freemkv uses a three-layer recovery model. See [`docs/rip-recovery.md`](docs/rip-recovery.md) for full details.
+
+- **Pass 1 (Disc::copy):** Fast sweep with 64 KB reads. On failure, zero-fills the block and skips forward. Writes a ddrescue-format mapfile for later retry.
+- **Pass 2+ (Disc::patch):** Targeted re-reads of bad ranges with a long 30-second timeout per CDB. The drive firmware performs its own ECC and laser power retries within that window.
+- **In-stream (DiscStream):** Adaptive batch halving -- reduces request size on failure to isolate bad sectors within a larger block.
+
+This means a disc with some bad sectors will still produce a usable ISO. The damaged areas are zero-filled in pass 1 and retried in subsequent passes. Structure-protected sectors (deliberate unreadable regions from copy protection) will never yield, which is expected.
+
+### The Drive Taint Issue (LG BU40N)
+
+Some drives, notably the LG BU40N, exhibit a "taint" behavior after encountering MEDIUM ERRORs:
+
+1. The drive hits a damaged sector and returns a MEDIUM ERROR.
+2. From that point forward, **all subsequent reads fail** -- even reads to sectors that were previously successful.
+3. The only recovery is to physically unplug and reconnect the drive (or power-cycle it).
+
+This is not a freemkv bug. It is a drive firmware behavior triggered by the interaction between the drive's internal error recovery and the USB-SATA bridge's handling of the error response. The drive firmware enters a degraded state that it does not recover from without a power cycle.
+
+Workarounds:
+
+- **Use a direct SATA connection.** This eliminates the bridge interaction that triggers the taint.
+- **Use a different bridge.** The ASM1153 and JMS578 are less likely to trigger this behavior.
+- **Accept the partial ISO.** freemkv's skip-forward recovery will zero-fill the unreadable blocks and continue. The resulting ISO may be playable with minor glitches in the affected areas.
+- **Physical replug between retry passes.** If running multi-pass patch, replug the drive between passes to clear the taint state.
+
+freemkv deliberately does not attempt inline SCSI resets or eject cycles to recover from this state, because those operations were found to make the problem worse on affected hardware (see the design rationale in [`docs/rip-recovery.md`](docs/rip-recovery.md)).
+
+---
+
+## 3. Drive Not Detected
+
+### Check Hardware Visibility
+
+```bash
+lsusb
+```
+
+Verify the drive appears in the USB device list. If it does not show up, the drive is not visible to the host at all -- check cables, power, and USB port.
+
+```bash
+ls /dev/sg*
+```
+
+On Linux, optical drives appear as `/dev/sg*` devices (the SCSI Generic interface). freemkv uses `/dev/sg*`, not `/dev/sr*`. If `lsusb` shows the device but no `/dev/sg*` entry exists, the `sg` kernel module may not be loaded:
+
+```bash
+sudo modprobe sg
+```
+
+### Check Kernel Messages
+
+```bash
+dmesg | grep -i usb | tail -30
+dmesg | grep -i sg | tail -10
+```
+
+Look for:
+- USB enumeration errors or failed port resets.
+- `sg_add` messages confirming the sg device was registered.
+- Permission denied or access errors.
+
+### Permission Issues
+
+On most Linux distributions, `/dev/sg*` devices are owned by `root:disk` or `root:cdrom` with restricted permissions. Running freemkv as an unprivileged user will fail with permission errors.
+
+Options:
+
+- Add your user to the appropriate group:
+
+  ```bash
+  sudo usermod -aG disk $USER
+  ```
+
+  Then log out and back in for the change to take effect. On some distributions the group is `cdrom` or `optical` instead of `disk`.
+
+- Run with elevated privileges:
+
+  ```bash
+  sudo freemkv ...
+  ```
+
+- Install a udev rule for persistent per-device permissions. Create `/etc/udev/rules.d/99-sg-optical.rules`:
+
+  ```
+  SUBSYSTEM=="scsi_generic", ATTRS{type}=="5", MODE="0666"
+  ```
+
+  Then reload udev rules:
+
+  ```bash
+  sudo udevadm control --reload-rules && sudo udevadm trigger
+  ```
+
+### Spin-Up Delay
+
+Optical drives take 30-60 seconds to spin up and become ready after hot-plug or disc insertion. During this window, SCSI commands may return NOT READY or timeout.
+
+freemkv's `Drive::wait_ready()` handles this automatically by polling with TEST UNIT READY until the drive responds. If you are writing your own code using the library, always call `wait_ready()` before `init()`:
+
+```rust
+let mut drive = Drive::open(Path::new("/dev/sg4"))?;
+drive.wait_ready()?;  // blocks until disc is ready, up to 30s
+drive.init()?;
+```
+
+If the drive was just plugged in, wait a full minute before concluding it is not detected.
+
+---
+
+## 4. How to Identify Your USB-SATA Bridge
+
+If you are experiencing the issues described in section 1, you need to know which bridge chipset your adapter or enclosure uses.
+
+### Step 1: Find the Device
+
+```bash
+lsusb
+```
+
+Look for entries matching your drive or enclosure. Bridges may appear under their own manufacturer name or as a generic SATA device. Common examples:
+
+```
+Bus 002 Device 005: ID 13fd:0840 Initio Corporation
+Bus 002 Device 006: ID 174c:1153 ASMedia Technology Inc. ASM1153
+Bus 002 Device 007: ID 152d:0578 JMicron Technology Corp. JMS578
+```
+
+### Step 2: Match the IDs
+
+| Vendor | Product ID | Chipset | Status |
+|--------|-----------|---------|--------|
+| `13fd` | `3609` | Initio INIC-3609 | Affected. Apply quirk. |
+| `13fd` | `3940` | Initio INIC-3619 | Affected. Apply quirk. |
+| `13fd` | `0840` | Initio INIC-3069 | Affected. Apply quirk. |
+| `174c` | `5106` | ASMedia ASM1051 | Affected (early firmware). Apply quirk. |
+| `174c` | `1153` | ASMedia ASM1153 | Good. No quirk needed. |
+| `152d` | `0561` | JMicron JMB36x | Affected (some firmware). Apply quirk if issues occur. |
+| `152d` | `0578` | JMicron JMS578 | Good. No quirk needed. |
+
+### Step 3: Check dmesg for the Bridge Name
+
+```bash
+dmesg | grep -i "usb-storage\|uas\|initio\|asmedia\|jmicron"
+```
+
+This often reveals the bridge chipset even when `lsusb` shows a generic name.
+
+### Step 4: If the Enclosure Is Sealed
+
+Many external drive enclosures (Vantec NexStar, Sabrent, OWC, etc.) do not advertise the bridge chipset on the packaging. In this case:
+
+1. Check `lsusb` while the enclosure is connected.
+2. Search the vendor:product ID online -- there are community-maintained lists of which chipsets popular enclosures use.
+3. If you cannot determine the chipset and are experiencing bridge crashes, assume it is an Initio and apply the quirk with its IDs.
+4. The definitive test: connect the bare drive to a motherboard SATA port. If the problems disappear, the bridge was the cause.
+
+---
+
+## 5. General Debugging Checklist
+
+When something goes wrong during a rip, gather this information before filing an issue:
+
+1. **freemkv version:** `freemkv --version` or the crate version in `Cargo.toml`.
+2. **Drive model:** from the drive label, or from `freemkv info`.
+3. **Connection type:** USB (with bridge chipset if known) or direct SATA.
+4. **Operating system and kernel:** `uname -a`.
+5. **Kernel messages during the failure:** `dmesg | tail -50` immediately after the crash.
+6. **SCSI device:** which `/dev/sg*` the drive was on, and whether it changed after the failure.
+7. **The disc:** title, format (BD/DVD/UHD), condition.
+
+Include all of the above in bug reports. SCSI transport errors that resolve with the `US_FL_IGNORE_RESIDUE` quirk or by switching to direct SATA are bridge firmware bugs, not freemkv bugs.

benches/sgio_read.rs

@@ -8,13 +8,12 @@ fn main() {
     let device = std::env::args()
         .skip(1)
         .find(|a| !a.starts_with('-'))
-        .unwrap_or_else(|| {
-            let drives = libfreemkv::find_drives();
-            if drives.is_empty() {
+        .unwrap_or_else(|| match libfreemkv::find_drive() {
+            Some(d) => d.device_path().to_string(),
+            None => {
                 eprintln!("No drives found");
                 std::process::exit(1);
             }
-            drives[0].device_path().to_string()
         });
 
     let mut drive = Drive::open(Path::new(&device)).unwrap_or_else(|e| {

build.rs

@@ -3,5 +3,34 @@ fn main() {
     if target == "macos" {
         println!("cargo:rustc-link-lib=framework=IOKit");
         println!("cargo:rustc-link-lib=framework=CoreFoundation");
+
+        let out_dir = std::env::var("OUT_DIR").unwrap();
+        let obj = format!("{out_dir}/macos_shim.o");
+        let lib = format!("{out_dir}/libmacos_scsi.a");
+
+        std::process::Command::new("cc")
+            .args([
+                "-c",
+                "src/scsi/macos_shim.c",
+                "-o",
+                &obj,
+                "-framework",
+                "IOKit",
+                "-framework",
+                "CoreFoundation",
+                "-Wall",
+                "-O2",
+            ])
+            .status()
+            .expect("failed to compile macos_shim.c");
+
+        std::process::Command::new("ar")
+            .args(["rcs", &lib, &obj])
+            .status()
+            .expect("failed to create static lib");
+
+        println!("cargo:rustc-link-search=native={out_dir}");
+        println!("cargo:rustc-link-lib=static=macos_scsi");
+        println!("cargo:rerun-if-changed=src/scsi/macos_shim.c");
     }
 }

docs/architecture.md

@@ -102,7 +102,7 @@ Recovery is layered above `Drive::read`, not inside it. Layer 1
 Layer 3 (`DiscStream::fill_extents` adaptive batch sizer) handles in-loop
 request-size adaptation. Inline recovery (gentle retry → SCSI reset → retry)
 was removed in 0.13.6 — see [`rip-recovery.md`](rip-recovery.md) and
-`(internal)/postmortems/2026-04-25-stop-wedge-and-zero-kbs.md`.
+the stop-wedge postmortem (2026-04-25).
 
 ---
 

docs/drive-access.md

@@ -67,7 +67,7 @@ Recovery is layered above `Drive::read`:
   streak.
 
 Inline recovery (5× gentle retry → close + reset + reopen → 5× more) was
-removed in 0.13.6. See `(internal)/postmortems/2026-04-25-stop-wedge-and-zero-kbs.md`
+removed in 0.13.6. See the stop-wedge postmortem (2026-04-25)
 for rationale: the inline reset wedged drive firmware on the LG BU40N (Initio
 USB-SATA bridge) without ever recovering a sector. See
 [`rip-recovery.md`](rip-recovery.md) for the full three-layer model.

docs/rip-recovery.md

@@ -133,8 +133,8 @@ implement retry logic.
 no eject cycle. The `recovery` flag controls only the per-CDB timeout
 (1.5 s vs. 30 s); on any failure it returns `Err(DiscRead)` immediately.
 Inline recovery (5× gentle retry → close + SCSI reset + reopen → 5× more)
-was removed in 0.13.6. See `(internal)/postmortems/2026-04-25-stop-wedge-and-zero-kbs.md`
-for rationale: the inline reset on the LG BU40N (Initio USB-SATA bridge)
+was removed in 0.13.6. See the stop-wedge postmortem (2026-04-25) for rationale:
+the inline reset on the LG BU40N (Initio USB-SATA bridge)
 wedged drive firmware below the bridge without ever recovering a sector,
 and the gentle-retry phase produced long stretches of 0 KB/s with no
 recoveries to show for it. Recovery responsibility is now layered: layer 1

src/disc/mapfile.rs

@@ -69,12 +69,28 @@ pub struct MapEntry {
 }
 
 /// Summary statistics over all entries.
+///
+/// `bytes_pending` aggregates `NonTried + NonTrimmed + NonScraped` for
+/// back-compat. `bytes_nontried` and `bytes_retryable` (= NonTrimmed +
+/// NonScraped) split that aggregate so UIs can distinguish *unread*
+/// territory (still ahead of Pass 1's read head) from *needs-retry*
+/// territory (Pass 1 already encountered, queued for Pass 2-N).
 #[derive(Debug, Clone, Copy, Default)]
 pub struct MapStats {
     pub bytes_total: u64,
     pub bytes_good: u64,
     pub bytes_unreadable: u64,
     pub bytes_pending: u64,
+    /// Sectors Pass 1 hasn't reached yet (`NonTried`). Subset of
+    /// `bytes_pending`.
+    pub bytes_nontried: u64,
+    /// Sectors flagged for Pass 2-N retry — `NonTrimmed` (multi-sector
+    /// read failed; needs split) + `NonScraped` (small-block read
+    /// partially recovered; remainder still pending). Subset of
+    /// `bytes_pending`. This is the right signal for a "MAYBE / will
+    /// retry" UI bucket; `bytes_pending` over-counts because it folds
+    /// in `bytes_nontried`.
+    pub bytes_retryable: u64,
 }
 
 /// Write-through mapfile. Every `record()` persists to disk immediately
@@ -275,8 +291,13 @@ impl Mapfile {
             match e.status {
                 SectorStatus::Finished => s.bytes_good += e.size,
                 SectorStatus::Unreadable => s.bytes_unreadable += e.size,
-                SectorStatus::NonTried | SectorStatus::NonTrimmed | SectorStatus::NonScraped => {
-                    s.bytes_pending += e.size
+                SectorStatus::NonTried => {
+                    s.bytes_pending += e.size;
+                    s.bytes_nontried += e.size;
+                }
+                SectorStatus::NonTrimmed | SectorStatus::NonScraped => {
+                    s.bytes_pending += e.size;
+                    s.bytes_retryable += e.size;
                 }
             }
         }
@@ -297,7 +318,7 @@ impl Mapfile {
             let mut w = std::io::BufWriter::new(file);
             writeln!(
                 w,
-                "# Rescue Logfile. Created by libfreemkv v{}",
+                "# Rescue Logfile. Created by {}",
                 self.version
             )?;
             writeln!(w, "# Current pos / status / pass / pass_time")?;

src/disc/mod.rs

@@ -13,7 +13,7 @@ mod dvd;
 mod encrypt;
 pub mod mapfile;
 
-use crate::drive::Drive;
+use crate::drive::{Drive, extract_scsi_context};
 use crate::error::{Error, Result};
 use crate::sector::SectorReader;
 use crate::udf;
@@ -1210,29 +1210,124 @@ impl Disc {
         }
     }
 
-    /// Raw sector copy — write the entire disc image to a file.
+    /// Copy disc sectors to an ISO image file.
     ///
-    /// NOT a stream operation. Copies sectors 0→capacity byte-for-byte producing
-    /// a valid ISO/UDF image. Records progress in a ddrescue-format mapfile at
+    /// NOT a stream operation. Copies sectors byte-for-byte producing a valid
+    /// ISO/UDF image. Records progress in a ddrescue-format mapfile at
     /// `path + ".mapfile"` — flushed every block for crash-safe resume.
     ///
-    /// # Options
-    /// - **default** (all false): behavior matches pre-v0.11.21 — uses full
-    ///   drive recovery (may take minutes per bad sector), aborts on error.
-    ///   Mapfile is produced as a side-effect.
-    /// - **skip_on_error**: zero-fill bad blocks in the ISO, mark them in the
-    ///   mapfile, and continue. Uses fast reads (no drive-level recovery loop).
-    /// - **skip_forward** (implies skip_on_error): on block failure, also skip
-    ///   forward by an exponentially-growing amount, marking the jumped region
-    ///   as `non-trimmed` for later trimming/scraping by `Disc::patch`.
-    /// - **resume**: if the mapfile exists, resume from its state — only
-    ///   `non-tried` ranges are read. Without `resume`, a fresh mapfile is
-    ///   written and the ISO recreated from scratch.
+    /// Auto-detects the pass based on mapfile state:
+    /// - **No mapfile** → Pass 1 (sweep): sequential read of the entire disc,
+    ///   ECC-aligned batches, damage-jump on contiguous failures, marks bad
+    ///   blocks as NonTrimmed. No drive-level recovery — fast.
+    /// - **Mapfile with bad ranges** → Pass N (patch): re-reads only bad ranges
+    ///   sector-by-sector with full drive-level recovery. Marks recovered
+    ///   sectors as Finished, failed as Unreadable (terminal).
+    /// - **Mapfile clean** → no-op: all sectors are Finished.
+    ///
+    /// Without `multipass`: aborts on the first read error (legacy single-pass).
     pub fn copy(
         &self,
         reader: &mut dyn SectorReader,
         path: &std::path::Path,
         opts: &CopyOptions,
+    ) -> Result<CopyResult> {
+        if opts.multipass {
+            let mf_path = self.mapfile_for(path);
+            if mf_path.exists() {
+                let map = mapfile::Mapfile::load(&mf_path)
+                    .map_err(|e| Error::IoError { source: e })?;
+                let stats = map.stats();
+                let disc_size = self.capacity_bytes;
+                let covers_disc = map.total_size() == disc_size;
+                let bad_bytes = stats.bytes_pending + stats.bytes_unreadable;
+                tracing::info!(
+                    "copy dispatch: disc={} map={} covers={} good={} nontried={} pending={} unreadable={}",
+                    disc_size,
+                    map.total_size(),
+                    covers_disc,
+                    stats.bytes_good,
+                    stats.bytes_nontried,
+                    stats.bytes_pending,
+                    stats.bytes_unreadable,
+                );
+                if covers_disc && bad_bytes == 0 {
+                    return Ok(CopyResult {
+                        bytes_total: disc_size,
+                        bytes_good: stats.bytes_good,
+                        bytes_unreadable: stats.bytes_unreadable,
+                        bytes_pending: 0,
+                        recovered_this_pass: 0,
+                        complete: true,
+                        halted: false,
+                    });
+                }
+                if !covers_disc || stats.bytes_nontried > 0 {
+                    tracing::info!(
+                        "copy dispatch: → sweep (covers_disc={}, nontried={})",
+                        covers_disc,
+                        stats.bytes_nontried,
+                    );
+                    return self.sweep_internal(reader, path, opts, true);
+                }
+                tracing::info!("copy dispatch: → patch");
+                return self.patch_internal(reader, path, opts);
+            }
+        }
+        self.sweep_internal(reader, path, opts, false)
+    }
+
+    fn sweep_internal(
+        &self,
+        reader: &mut dyn SectorReader,
+        path: &std::path::Path,
+        opts: &CopyOptions,
+        resume: bool,
+    ) -> Result<CopyResult> {
+        let sweep_opts = SweepOptions {
+            decrypt: opts.decrypt,
+            resume,
+            batch_sectors: None,
+            skip_on_error: opts.multipass,
+            progress: opts.progress,
+            halt: opts.halt.clone(),
+        };
+        self.sweep(reader, path, &sweep_opts)
+    }
+
+    fn patch_internal(
+        &self,
+        reader: &mut dyn SectorReader,
+        path: &std::path::Path,
+        opts: &CopyOptions,
+    ) -> Result<CopyResult> {
+        let patch_opts = PatchOpts {
+            decrypt: opts.decrypt,
+            block_sectors: Some(1),
+            full_recovery: true,
+            reverse: true,
+            wedged_threshold: 50,
+            progress: opts.progress,
+            halt: opts.halt.clone(),
+        };
+        let pr = self.patch(reader, path, &patch_opts)?;
+        Ok(CopyResult {
+            bytes_total: pr.bytes_total,
+            bytes_good: pr.bytes_good,
+            bytes_unreadable: pr.bytes_unreadable,
+            bytes_pending: pr.bytes_pending,
+            recovered_this_pass: pr.bytes_recovered_this_pass,
+            complete: pr.bytes_pending == 0 && pr.bytes_unreadable > 0
+                || pr.bytes_pending == 0 && pr.bytes_unreadable == 0,
+            halted: pr.halted,
+        })
+    }
+
+    fn sweep(
+        &self,
+        reader: &mut dyn SectorReader,
+        path: &std::path::Path,
+        opts: &SweepOptions,
     ) -> Result<CopyResult> {
         use std::io::{Seek, SeekFrom, Write};
 
@@ -1244,12 +1339,12 @@ impl Disc {
         };
 
         // Mapfile: load if resuming, else wipe + recreate.
-        let mapfile_path = mapfile_path_for(path);
+        let mapfile_path = self.mapfile_for(path);
         if !opts.resume {
             let _ = std::fs::remove_file(&mapfile_path);
         }
         let mut map =
-            mapfile::Mapfile::open_or_create(&mapfile_path, total_bytes, env!("CARGO_PKG_VERSION"))
+            mapfile::Mapfile::open_or_create(&mapfile_path, total_bytes, concat!("libfreemkv v", env!("CARGO_PKG_VERSION")))
                 .map_err(|e| Error::IoError { source: e })?;
 
         // ISO file: if resuming and mapfile has Finished ranges, open existing;
@@ -1274,15 +1369,10 @@ impl Disc {
         let mut file = file;
         let batch: u16 = match opts.batch_sectors {
             Some(b) => b,
-            None if opts.skip_forward => 32, // 64 KB = BD ECC block size
+            None if opts.skip_on_error => ecc_sectors(self.format),
             None => DEFAULT_BATCH_SECTORS,
         };
 
-        // Skip-forward state.
-        let skip_init = 256 * 1024u64; // 256 KB
-        let skip_max = (total_bytes / 100).max(skip_init); // cap at 1% of disc
-        let mut skip_size = skip_init;
-
         let mut buf = vec![0u8; batch as usize * 2048];
         let mut bytes_done = 0u64;
         let mut halt_requested = false;
@@ -1291,18 +1381,27 @@ impl Disc {
         let mut read_ok_count: u64 = 0;
         let mut read_err_count: u64 = 0;
         let mut last_log_iter: u64 = 0;
+        let mut not_ready_retries: u32 = 0;
+        const NOT_READY_MAX_RETRIES: u32 = 3;
+        let mut bridge_degradation_count: u32 = 0;
+        const BRIDGE_DEGRADATION_MAX: u32 = 5;
+        const BRIDGE_DEGRADATION_COOLDOWN_SECS: u64 = 10;
+        const DAMAGE_WINDOW: usize = 16;
+        const DAMAGE_THRESHOLD_PCT: usize = 12;
+        const JUMP_SECTORS_FACTOR: u64 = 256;
+        let mut damage_window: Vec<bool> = Vec::with_capacity(DAMAGE_WINDOW);
+        let mut jump_multiplier: u64 = 1;
+        let mut consecutive_good: u64 = 0;
+        let mut in_damage_zone = false;
         tracing::trace!(
             target: "freemkv::disc",
             phase = "copy_start",
             total_bytes,
             batch,
-            skip_init,
-            skip_max,
+            skip_on_error = opts.skip_on_error,
             "Disc::copy entered"
         );
 
-        // Iterate over not-yet-finished regions from the mapfile. We re-read the
-        // mapfile after each block because record() mutates the region list.
         'outer: loop {
             let regions_to_do = map.ranges_with(&[
                 mapfile::SectorStatus::NonTried,
@@ -1318,9 +1417,6 @@ impl Disc {
             if regions_to_do.is_empty() {
                 break;
             }
-            // Only process the first NonTried range per outer pass; skip_forward
-            // may turn others into NonTrimmed which we DO NOT re-enter here —
-            // Disc::patch handles those.
             let Some((region_pos, region_size)) = map.next_with(0, mapfile::SectorStatus::NonTried)
             else {
                 break;
@@ -1343,61 +1439,212 @@ impl Disc {
                         break 'outer;
                     }
                 }
+
                 let block_bytes = (region_end - pos).min(batch as u64 * 2048);
-                let lba = (pos / 2048) as u32;
-                let count = (block_bytes / 2048) as u16;
-                let bytes = count as usize * 2048;
+                let block_lba = (pos / 2048) as u32;
+                let block_count = (block_bytes / 2048) as u16;
+                let recovery = !opts.skip_on_error;
 
-                let recovery = !opts.skip_on_error; // fast reads when skipping
-                iter_count += 1;
-                let read_t0 = std::time::Instant::now();
-                let read_ok = reader
-                    .read_sectors(lba, count, &mut buf[..bytes], recovery)
-                    .is_ok();
-                let read_elapsed_ms = read_t0.elapsed().as_millis() as u64;
+                let read_result = reader.read_sectors(
+                    block_lba,
+                    block_count,
+                    &mut buf[..block_bytes as usize],
+                    recovery,
+                );
 
-                if read_ok {
+                let mut did_skip_ahead = false;
+
+                if read_result.is_ok() {
                     read_ok_count += 1;
+                    damage_window.push(true);
+                    if damage_window.len() > DAMAGE_WINDOW {
+                        damage_window.remove(0);
+                    }
+                    consecutive_good += 1;
+                    if consecutive_good >= DAMAGE_WINDOW as u64 {
+                        jump_multiplier = 1;
+                        if in_damage_zone {
+                            in_damage_zone = false;
+                            reader.set_speed(0xFFFF);
+                            tracing::debug!(
+                                target: "freemkv::disc",
+                                phase = "damage_exit",
+                                lba = block_lba,
+                                "Exited damage zone; restoring max read speed"
+                            );
+                        }
+                    }
+                    bridge_degradation_count = 0;
+
                     if opts.decrypt {
-                        crate::decrypt::decrypt_sectors(&mut buf[..bytes], &keys, 0)?;
+                        crate::decrypt::decrypt_sectors(
+                            &mut buf[..block_bytes as usize],
+                            &keys,
+                            0,
+                        )?;
                     }
                     file.seek(SeekFrom::Start(pos))
                         .map_err(|e| Error::IoError { source: e })?;
-                    file.write_all(&buf[..bytes])
+                    file.write_all(&buf[..block_bytes as usize])
                         .map_err(|e| Error::IoError { source: e })?;
                     map.record(pos, block_bytes, mapfile::SectorStatus::Finished)
                         .map_err(|e| Error::IoError { source: e })?;
                     bytes_done = bytes_done.saturating_add(block_bytes);
-                    skip_size = skip_init; // reset after success
-                    pos += block_bytes;
-                } else if opts.skip_on_error {
+                } else if !opts.skip_on_error {
+                    let (status, sense) = read_result
+                        .as_ref()
+                        .err()
+                        .map(extract_scsi_context)
+                        .unwrap_or((0, None));
+                    return Err(Error::DiscRead {
+                        sector: block_lba as u64,
+                        status: Some(status),
+                        sense,
+                    });
+                } else {
+                    let err = read_result.err().unwrap();
                     read_err_count += 1;
-                    // Zero-fill this block, mark non-trimmed for later patch trim.
-                    buf[..bytes].fill(0);
+                    consecutive_good = 0;
+
+                    if err.is_scsi_transport_failure() {
+                        tracing::warn!(
+                            target: "freemkv::disc",
+                            phase = "transport_failure",
+                            lba = block_lba,
+                            error = %err,
+                            "transport failure (bridge crash); aborting copy — caller should USB reset + resume"
+                        );
+                        return Err(err);
+                    }
+
+                    if err.is_bridge_degradation() {
+                        if bridge_degradation_count < BRIDGE_DEGRADATION_MAX {
+                            bridge_degradation_count += 1;
+                            tracing::warn!(
+                                target: "freemkv::disc",
+                                phase = "bridge_degradation",
+                                lba = block_lba,
+                                degradation_count = bridge_degradation_count,
+                                error = %err,
+                                "bridge degradation; cooling down 10s"
+                            );
+                            std::thread::sleep(std::time::Duration::from_secs(BRIDGE_DEGRADATION_COOLDOWN_SECS));
+                            continue;
+                        }
+                        tracing::warn!(
+                            target: "freemkv::disc",
+                            phase = "bridge_degradation_exhausted",
+                            lba = block_lba,
+                            "bridge degradation retries exhausted; treating as bad sector"
+                        );
+                    }
+
+                    let sense = err.scsi_sense();
+                    let sense_key = sense.map(|s| s.sense_key).unwrap_or(0);
+                    let asc = sense.map(|s| s.asc).unwrap_or(0);
+                    let ascq = sense.map(|s| s.ascq).unwrap_or(0);
+
+                    if sense_key == crate::scsi::SENSE_KEY_NOT_READY && not_ready_retries < NOT_READY_MAX_RETRIES {
+                        not_ready_retries += 1;
+                        tracing::warn!(
+                            target: "freemkv::disc",
+                            phase = "not_ready_pause",
+                            lba = block_lba,
+                            sense_key,
+                            asc,
+                            ascq,
+                            retry = not_ready_retries,
+                            "NOT READY; pausing 3s then retrying"
+                        );
+                        std::thread::sleep(std::time::Duration::from_secs(3));
+                        continue;
+                    }
+                    not_ready_retries = 0;
+
+                    tracing::warn!(
+                        target: "freemkv::disc",
+                        phase = "skip_ecc_block",
+                        lba = block_lba,
+                        sectors = block_count,
+                        sense_key,
+                        asc,
+                        ascq,
+                        error = %err,
+                        "ECC block failed; marking NonTrimmed"
+                    );
+                    let zero = vec![0u8; block_bytes as usize];
                     file.seek(SeekFrom::Start(pos))
                         .map_err(|e| Error::IoError { source: e })?;
-                    file.write_all(&buf[..bytes])
+                    file.write_all(&zero)
                         .map_err(|e| Error::IoError { source: e })?;
                     map.record(pos, block_bytes, mapfile::SectorStatus::NonTrimmed)
                         .map_err(|e| Error::IoError { source: e })?;
-                    pos += block_bytes;
+                    bytes_done = bytes_done.saturating_add(block_bytes);
 
-                    if opts.skip_forward && pos < region_end {
-                        // Skip ahead; mark skipped bytes as non-trimmed too.
-                        let jump = skip_size.min(region_end - pos);
-                        if jump > 0 {
-                            map.record(pos, jump, mapfile::SectorStatus::NonTrimmed)
-                                .map_err(|e| Error::IoError { source: e })?;
-                            pos += jump;
+                    damage_window.push(false);
+                    if damage_window.len() > DAMAGE_WINDOW {
+                        damage_window.remove(0);
+                    }
+
+                    let bad_count = damage_window.iter().filter(|&&b| !b).count();
+                    if damage_window.len() >= DAMAGE_WINDOW
+                        && bad_count * 100 / damage_window.len() >= DAMAGE_THRESHOLD_PCT
+                    {
+                        let jump_sectors = JUMP_SECTORS_FACTOR * batch as u64 * jump_multiplier;
+                        let jump_lba = ((pos / 2048) + jump_sectors) as u32;
+                        let region_end_lba = (region_end / 2048) as u32;
+                        if jump_lba < region_end_lba {
+                            if !in_damage_zone {
+                                in_damage_zone = true;
+                                reader.set_speed(0x0000);
+                                tracing::debug!(
+                                    target: "freemkv::disc",
+                                    phase = "damage_enter",
+                                    lba = block_lba,
+                                    "Entered damage zone; dropping to minimum read speed"
+                                );
+                            }
+                            let jump_pos = jump_lba as u64 * 2048;
+                            let gap_start = pos + block_bytes;
+                            let gap_bytes = jump_pos.saturating_sub(gap_start);
+                            let jump_mb = gap_bytes / 1_048_576;
+                            tracing::warn!(
+                                target: "freemkv::disc",
+                                phase = "damage_jump",
+                                from_lba = block_lba,
+                                to_lba = jump_lba,
+                                jump_mb,
+                                bad_pct = bad_count * 100 / damage_window.len(),
+                                multiplier = jump_multiplier,
+                                "25%+ failures in last 50 blocks; jumping ahead"
+                            );
+                            if gap_bytes > 0 {
+                                let zero = vec![0u8; 65536];
+                                let mut filled: u64 = 0;
+                                while filled < gap_bytes {
+                                    let chunk = (gap_bytes - filled).min(zero.len() as u64);
+                                    file.seek(SeekFrom::Start(gap_start + filled))
+                                        .map_err(|e| Error::IoError { source: e })?;
+                                    file.write_all(&zero[..chunk as usize])
+                                        .map_err(|e| Error::IoError { source: e })?;
+                                    filled += chunk;
+                                }
+                                map.record(gap_start, gap_bytes, mapfile::SectorStatus::NonTrimmed)
+                                    .map_err(|e| Error::IoError { source: e })?;
+                                bytes_done = bytes_done.saturating_add(gap_bytes);
+                            }
+                            pos = jump_pos;
+                            jump_multiplier *= 2;
+                            did_skip_ahead = true;
                         }
-                        skip_size = (skip_size * 2).min(skip_max);
                     }
-                } else {
-                    // Current behavior (pre-0.11.21): abort on first bad sector.
-                    return Err(Error::DiscRead { sector: lba as u64 });
                 }
 
-                // Throttled iter telemetry — every 100 inner iterations.
+                if !did_skip_ahead {
+                    pos += block_bytes;
+                }
+                iter_count += 1;
+
                 if iter_count - last_log_iter >= 100 {
                     last_log_iter = iter_count;
                     let stats = map.stats();
@@ -1407,10 +1654,8 @@ impl Disc {
                         iter_count,
                         read_ok_count,
                         read_err_count,
-                        last_read_ms = read_elapsed_ms,
                         pos,
                         region_end,
-                        skip_size,
                         bytes_good = stats.bytes_good,
                         bytes_pending = stats.bytes_pending,
                         copy_elapsed_ms = copy_t0.elapsed().as_millis() as u64,
@@ -1425,6 +1670,7 @@ impl Disc {
                         work_done: pos,
                         work_total: total_bytes,
                         bytes_good_total: stats.bytes_good,
+                        bytes_bad_total: stats.bytes_unreadable + stats.bytes_retryable,
                         bytes_total_disc: total_bytes,
                     });
                 }
@@ -1450,123 +1696,94 @@ impl Disc {
             bytes_good: stats.bytes_good,
             bytes_unreadable: stats.bytes_unreadable,
             bytes_pending: stats.bytes_pending,
+            recovered_this_pass: 0,
             complete: stats.bytes_pending == 0 && !halt_requested,
             halted: halt_requested,
         })
     }
 }
 
-/// Options for `Disc::copy`. All fields default to the pre-v0.11.21 behavior
-/// (recovery reads, abort on bad sector).
 #[derive(Default)]
 pub struct CopyOptions<'a> {
     pub decrypt: bool,
-    /// Resume from existing mapfile + ISO if present. Without this, any
-    /// existing mapfile is wiped and the ISO recreated.
-    pub resume: bool,
-    /// Override the default block size in sectors. Callers should resolve
-    /// this with `detect_max_batch_sectors(device_path)` for live drives.
-    /// When `None`, falls back to 32 sectors (64 KB BD ECC block) in
-    /// `skip_forward` mode or `DEFAULT_BATCH_SECTORS=60` otherwise.
-    pub batch_sectors: Option<u16>,
-    /// Zero-fill bad blocks in the ISO, mark them in the mapfile, continue.
-    /// Uses fast reads (no drive-level recovery loop).
-    pub skip_on_error: bool,
-    /// ddrescue-style exponential skip-forward on block failure. Implies
-    /// `skip_on_error`. The skipped region is marked `non-trimmed` for later
-    /// trimming/scraping by `Disc::patch`.
-    pub skip_forward: bool,
-    /// Per-iteration progress reporter. v0.13.16 architecture: the library
-    /// emits a single `PassProgress` shape via the `Progress` trait;
-    /// consumers compute their own derived percentages / ETAs from it. No
-    /// more positional `(bytes_good, pos, total)` callbacks.
+    pub multipass: bool,
     pub progress: Option<&'a dyn crate::progress::Progress>,
     pub halt: Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
 }
 
-/// Result of `Disc::copy`. `complete=true` means every byte reached a terminal
-/// state (Finished or Unreadable). `complete=false` means there's still pending
-/// work (halt, abort, or non-tried ranges) that `Disc::patch` or a resumed
-/// `Disc::copy` would continue.
 #[derive(Debug, Clone, Copy)]
 pub struct CopyResult {
     pub bytes_total: u64,
     pub bytes_good: u64,
     pub bytes_unreadable: u64,
     pub bytes_pending: u64,
+    pub recovered_this_pass: u64,
     pub complete: bool,
     pub halted: bool,
 }
 
-/// Sidecar mapfile path for a given ISO path — `foo.iso` → `foo.iso.mapfile`.
-pub fn mapfile_path_for(iso_path: &std::path::Path) -> std::path::PathBuf {
-    let mut s = iso_path.as_os_str().to_os_string();
-    s.push(".mapfile");
-    std::path::PathBuf::from(s)
-}
-
-/// Options for `Disc::patch`. Idempotent — each call is one patch attempt.
-#[derive(Default)]
-pub struct PatchOptions<'a> {
+pub(crate) struct SweepOptions<'a> {
     pub decrypt: bool,
-    /// Sector-granularity block size for retries. Defaults to 1 sector (2 KB).
-    pub block_sectors: Option<u16>,
-    /// Use full drive-level recovery on each read (slow but thorough). Defaults
-    /// to true — patch is the pass where we *want* the drive to try hard.
-    pub full_recovery: bool,
-    /// Walk bad ranges in reverse order, and within each range walk sectors
-    /// from high to low LBA. Useful for drives that wedge after a forward
-    /// read of a bad sector — approaching the post-bad-zone from end-of-disc
-    /// reads good sectors before the drive sees a bad one.
-    pub reverse: bool,
-    /// Bail out early if this many consecutive read failures occur with zero
-    /// successful reads in the same pass — i.e. the drive is wedged on the
-    /// bad zone and won't recover during this attempt. `0` disables the
-    /// guard (run to completion or halt).
-    pub wedged_threshold: u64,
-    /// Per-iteration progress reporter. See `CopyOptions::progress`.
+    pub resume: bool,
+    pub batch_sectors: Option<u16>,
+    pub skip_on_error: bool,
     pub progress: Option<&'a dyn crate::progress::Progress>,
     pub halt: Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
 }
 
-/// Result of `Disc::patch` — how many bad bytes were recovered, plus
-/// per-block counters for diagnosing why a pass made or didn't make progress.
-#[derive(Debug, Clone, Copy)]
-pub struct PatchResult {
+pub(crate) struct PatchOpts<'a> {
+    pub decrypt: bool,
+    pub block_sectors: Option<u16>,
+    pub full_recovery: bool,
+    pub reverse: bool,
+    pub wedged_threshold: u64,
+    pub progress: Option<&'a dyn crate::progress::Progress>,
+    pub halt: Option<std::sync::Arc<std::sync::atomic::AtomicBool>>,
+}
+
+pub(crate) struct PatchOutcome {
     pub bytes_total: u64,
     pub bytes_good: u64,
     pub bytes_unreadable: u64,
     pub bytes_pending: u64,
     pub bytes_recovered_this_pass: u64,
     pub halted: bool,
-    /// Total inner-loop iterations this pass (one per block attempted).
     pub blocks_attempted: u64,
-    /// Reads that returned Ok and were promoted to `Finished`.
     pub blocks_read_ok: u64,
-    /// Reads that returned Err and were marked `Unreadable`.
     pub blocks_read_failed: u64,
-    /// Pass exited early because `wedged_threshold` consecutive failures
-    /// occurred with zero successful reads — drive appears wedged on the
-    /// bad zone for this pass.
     pub wedged_exit: bool,
 }
 
+pub fn mapfile_path_for(iso_path: &std::path::Path) -> std::path::PathBuf {
+    let mut s = iso_path.as_os_str().to_os_string();
+    s.push(".mapfile");
+    std::path::PathBuf::from(s)
+}
+
 impl Disc {
-    /// Patch an existing ISO using its sidecar mapfile. Re-reads every range
-    /// that's not yet `+` (Finished) and writes successful bytes into the ISO
-    /// at their exact offsets. Updates mapfile entries as it goes.
-    ///
-    /// Idempotent — call repeatedly to apply more retry attempts. Stops early
-    /// if a pass recovered zero bytes (no point continuing).
-    pub fn patch(
+    fn mapfile_for(&self, path: &std::path::Path) -> std::path::PathBuf {
+        if path.as_os_str() == "/dev/null" {
+            let name: String = self.meta_title.as_deref().unwrap_or(&self.volume_id)
+                .chars()
+                .map(|c| if c.is_ascii_alphanumeric() || c == '-' || c == '_' { c } else { '_' })
+                .collect();
+            std::path::PathBuf::from(format!("/tmp/{name}.mapfile"))
+        } else {
+            mapfile_path_for(path)
+        }
+    }
+}
+
+impl Disc {
+    fn patch(
         &self,
         reader: &mut dyn SectorReader,
         path: &std::path::Path,
-        opts: &PatchOptions,
-    ) -> Result<PatchResult> {
+        opts: &PatchOpts,
+    ) -> Result<PatchOutcome> {
         use std::io::{Seek, SeekFrom, Write};
 
-        let mapfile_path = mapfile_path_for(path);
+        let mapfile_path = self.mapfile_for(path);
         let mut map =
             mapfile::Mapfile::load(&mapfile_path).map_err(|e| Error::IoError { source: e })?;
         let total_bytes = map.total_size();
@@ -1591,6 +1808,7 @@ impl Disc {
         let mut blocks_read_ok: u64 = 0;
         let mut blocks_read_failed: u64 = 0;
         let mut consecutive_failures: u64 = 0;
+        let mut unreadable_count: u64 = 0;
         let mut buf = vec![0u8; block_sectors as usize * 2048];
 
         // Collect bad ranges up front. Iterating while mutating is fragile;
@@ -1655,9 +1873,30 @@ impl Disc {
                 let count = (block_bytes / 2048) as u16;
                 let bytes = count as usize * 2048;
                 blocks_attempted += 1;
-                let read_ok = reader
-                    .read_sectors(lba, count, &mut buf[..bytes], recovery)
-                    .is_ok();
+                let read_result = reader.read_sectors(lba, count, &mut buf[..bytes], recovery);
+                // 0.13.23: parity with Disc::copy — bail immediately on a
+                // non-marginal SCSI sense (transport failure, HARDWARE
+                // ERROR, DATA PROTECT, UNIT ATTENTION, NOT READY,
+                // ILLEGAL REQUEST, kernel IoError). The wedged_threshold
+                // counter is a defense-in-depth backstop for ~50
+                // consecutive marginal failures, but a single
+                // non-marginal error already proves the drive can't
+                // produce data this pass — don't waste 50× the timeout
+                // budget proving it again.
+                if let Err(ref e) = read_result {
+                    if !e.is_marginal_read() {
+                        let err = read_result.err().unwrap();
+                        tracing::trace!(
+                            target: "freemkv::disc",
+                            phase = "patch_bail",
+                            lba,
+                            error = %err,
+                            "patch read failed with non-marginal sense; bailing"
+                        );
+                        return Err(err);
+                    }
+                }
+                let read_ok = read_result.is_ok();
                 if read_ok {
                     blocks_read_ok += 1;
                     consecutive_failures = 0;
@@ -1673,6 +1912,7 @@ impl Disc {
                 } else {
                     blocks_read_failed += 1;
                     consecutive_failures += 1;
+                    unreadable_count += 1;
                     map.record(pos, block_bytes, mapfile::SectorStatus::Unreadable)
                         .map_err(|e| Error::IoError { source: e })?;
                 }
@@ -1725,6 +1965,7 @@ impl Disc {
                         work_done,
                         work_total,
                         bytes_good_total: s.bytes_good,
+                        bytes_bad_total: s.bytes_unreadable + s.bytes_retryable,
                         bytes_total_disc: total_bytes,
                     });
                 }
@@ -1733,18 +1974,19 @@ impl Disc {
 
         file.sync_all().map_err(|e| Error::IoError { source: e })?;
         let stats = map.stats();
-        tracing::trace!(
+        tracing::info!(
             target: "freemkv::disc",
             phase = "patch_done",
             blocks_attempted,
             blocks_read_ok,
             blocks_read_failed,
+            unreadable_count,
             wedged_exit,
             halted,
             bytes_recovered = stats.bytes_good.saturating_sub(bytes_good_before),
             "Disc::patch returning"
         );
-        Ok(PatchResult {
+        Ok(PatchOutcome {
             bytes_total: total_bytes,
             bytes_good: stats.bytes_good,
             bytes_unreadable: stats.bytes_unreadable,
@@ -1763,6 +2005,79 @@ const MAX_BATCH_SECTORS: u16 = 510;
 const DEFAULT_BATCH_SECTORS: u16 = 60;
 const MIN_BATCH_SECTORS: u16 = 3;
 
+pub(crate) fn ecc_sectors(format: DiscFormat) -> u16 {
+    match format {
+        DiscFormat::Uhd | DiscFormat::BluRay => 32,
+        DiscFormat::Dvd => 16,
+        DiscFormat::Unknown => 32,
+    }
+}
+
+/// Coarse damage tier for a finished or in-progress rip. Maps the
+/// observable signals (bad sector count + lost wallclock playback time)
+/// onto a small discrete classification so UIs can render a colored badge
+/// and operators can decide whether to rescan / replug / accept.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum DamageSeverity {
+    /// No bad sectors at all.
+    Clean,
+    /// 1–50 bad sectors AND <1 sec lost. Likely unnoticeable.
+    Cosmetic,
+    /// 51–500 sectors OR 1–30 sec lost. Visible artifacts possible.
+    Moderate,
+    /// 500+ sectors OR 30+ sec lost. Significant damage; consider rescan
+    /// or different drive.
+    Serious,
+}
+
+/// Classify damage severity from raw counters. `bad_sectors` is the
+/// number of sectors marked unreadable (or NonTrimmed pending Pass 2);
+/// `lost_ms` is the cumulative wallclock playback time those sectors
+/// represent (computed from the title's bytes-per-sec).
+pub fn classify_damage(bad_sectors: u64, lost_ms: f64) -> DamageSeverity {
+    if bad_sectors == 0 {
+        return DamageSeverity::Clean;
+    }
+    if bad_sectors >= 500 || lost_ms >= 30_000.0 {
+        return DamageSeverity::Serious;
+    }
+    if bad_sectors >= 51 || lost_ms >= 1_000.0 {
+        return DamageSeverity::Moderate;
+    }
+    DamageSeverity::Cosmetic
+}
+
+#[cfg(test)]
+mod severity_tests {
+    use super::*;
+    #[test]
+    fn clean_when_no_damage() {
+        assert_eq!(classify_damage(0, 0.0), DamageSeverity::Clean);
+    }
+    #[test]
+    fn cosmetic_for_a_handful() {
+        assert_eq!(classify_damage(1, 5.0), DamageSeverity::Cosmetic);
+        assert_eq!(classify_damage(50, 999.0), DamageSeverity::Cosmetic);
+    }
+    #[test]
+    fn moderate_threshold_by_sectors() {
+        assert_eq!(classify_damage(51, 0.0), DamageSeverity::Moderate);
+    }
+    #[test]
+    fn moderate_threshold_by_time() {
+        assert_eq!(classify_damage(10, 1_000.0), DamageSeverity::Moderate);
+    }
+    #[test]
+    fn serious_threshold_by_sectors() {
+        assert_eq!(classify_damage(500, 0.0), DamageSeverity::Serious);
+    }
+    #[test]
+    fn serious_threshold_by_time() {
+        assert_eq!(classify_damage(10, 30_000.0), DamageSeverity::Serious);
+    }
+}
+
 /// Detect the maximum transfer size in sectors for a device.
 /// Reads /sys/block/<dev>/queue/max_hw_sectors_kb on Linux.
 /// For sg devices, resolves the corresponding block device via sysfs.

src/drive/macos.rs

@@ -1,26 +1,25 @@
 //! macOS drive discovery and device resolution.
+//!
+//! `find_drives` uses IOKit registry enumeration (via `scsi::list_drives`)
+//! to discover optical drives without exclusive access or unmounts. Only
+//! the returned paths are then opened for INQUIRY to build full `DriveId`.
 
 use crate::error::{Error, Result};
 use crate::identity::DriveId;
 
 pub fn find_drives() -> Vec<(String, DriveId)> {
     let mut drives = Vec::new();
-    for i in 0..16 {
-        let path = format!("/dev/disk{}", i);
-        if !std::path::Path::new(&path).exists() {
-            continue;
-        }
-        match crate::scsi::open(std::path::Path::new(&path)) {
+    let discovered = crate::scsi::list_drives();
+    for info in discovered {
+        let path = std::path::Path::new(&info.path);
+        match crate::scsi::open(path) {
             Ok(mut transport) => {
                 if let Ok(id) = DriveId::from_drive(transport.as_mut()) {
-                    if !id.raw_inquiry.is_empty() && (id.raw_inquiry[0] & 0x1F) == 0x05 {
-                        drives.push((path, id));
-                    }
+                    drives.push((info.path.clone(), id));
                 }
             }
             Err(_) => {
-                // Device exists but can't be opened (likely mounted).
-                // Use `diskutil unmountDisk /dev/diskN` to unmount before accessing.
+                continue;
             }
         }
     }

src/drive/mod.rs

@@ -1,11 +1,15 @@
 //! Drive session — open, identify, and read from optical drives.
 //!
-//! Three-step open:
-//!   1. `open()` — open device, identify drive. Always OEM.
-//!   2. `wait_ready()` — wait for disc to spin up. Call before reading.
-//!   3. `init()` — activate custom firmware. Removes riplock.
 //!   4. `probe_disc()` — probe disc surface. Drive learns optimal speeds.
 
+pub(crate) fn extract_scsi_context(e: &Error) -> (u8, Option<crate::scsi::ScsiSense>) {
+    match e {
+        Error::ScsiError { status, sense, .. } => (*status, *sense),
+        Error::DiscRead { status, sense, .. } => (status.unwrap_or(0), *sense),
+        _ => (0, None),
+    }
+}
+
 pub mod capture;
 
 // Per-platform discovery helpers (the `pub(crate)` `find_drives` /
@@ -160,11 +164,6 @@ impl Drive {
         self.unlock_tray();
     }
 
-    // NOTE: Debug aid — remove after fd issue is resolved
-    pub fn device_path_owned(&self) -> String {
-        self.device_path.clone()
-    }
-
     /// Whether this drive has a known profile (unlock parameters available).
     pub fn has_profile(&self) -> bool {
         self.profile.is_some()
@@ -177,31 +176,16 @@ impl Drive {
 
     pub fn wait_ready(&mut self) -> Result<()> {
         let tur = [SCSI_TEST_UNIT_READY, 0x00, 0x00, 0x00, 0x00, 0x00];
-        let mut tried_reset = false;
 
         for _ in 0..60 {
             let mut buf = [0u8; 0];
-            match self.scsi.as_mut().execute(
-                &tur,
-                crate::scsi::DataDirection::None,
-                &mut buf,
-                5_000,
-            ) {
-                Ok(_) => return Ok(()),
-                Err(Error::ScsiError { sense_key: 5, .. }) if !tried_reset => {
-                    // Illegal Request on TUR — drive may be stuck from a previous session.
-                    // Try reset() which attempts multiple recovery approaches.
-                    tried_reset = true;
-                    if self.reset().is_ok() {
-                        return Ok(());
-                    }
-                    // If reset failed but disc is present, proceed anyway —
-                    // the scan path will handle errors individually.
-                    if self.drive_status() == DriveStatus::DiscPresent {
-                        return Ok(());
-                    }
-                }
-                Err(_) => {}
+            if self
+                .scsi
+                .as_mut()
+                .execute(&tur, crate::scsi::DataDirection::None, &mut buf, 5_000)
+                .is_ok()
+            {
+                return Ok(());
             }
             std::thread::sleep(std::time::Duration::from_millis(500));
         }
@@ -256,94 +240,18 @@ impl Drive {
                     5_000,
                 ) {
                     Ok(_) => DriveStatus::DiscPresent,
-                    Err(Error::ScsiError { sense_key: 2, .. }) => DriveStatus::NotReady,
-                    Err(Error::ScsiError { sense_key: 6, .. }) => DriveStatus::NotReady, // UNIT ATTENTION
+                    Err(ref e)
+                        if e.scsi_sense()
+                            .is_some_and(|s| s.is_not_ready() || s.is_unit_attention()) =>
+                    {
+                        DriveStatus::NotReady
+                    }
                     _ => DriveStatus::Unknown,
                 }
             }
         }
     }
 
-    /// Attempt to reset the drive to a clean state.
-    ///
-    /// Escalates through increasingly aggressive recovery:
-    /// 1. Unlock tray + stop/start — handles normal stuck states
-    /// 2. Eject cycle — clears LibreDrive firmware stuck state (proven on BU40N)
-    /// 3. Re-init — firmware re-upload if profile available
-    ///
-    /// Note: step 2 physically ejects the tray. On slimline drives the user
-    /// must push it back in manually. Returns Ok(()) if TUR succeeds after
-    /// any step, even if the drive reports "tray open" (that's a valid state).
-    pub fn reset(&mut self) -> Result<()> {
-        let mut buf = [0u8; 0];
-        let tur = [SCSI_TEST_UNIT_READY, 0x00, 0x00, 0x00, 0x00, 0x00];
-
-        // 1. Unlock + stop/start
-        self.unlock_tray();
-        let stop = [SCSI_START_STOP_UNIT, 0x00, 0x00, 0x00, 0x00, 0x00];
-        let _ =
-            self.scsi
-                .as_mut()
-                .execute(&stop, crate::scsi::DataDirection::None, &mut buf, 5_000);
-        std::thread::sleep(std::time::Duration::from_millis(500));
-        let start = [SCSI_START_STOP_UNIT, 0x00, 0x00, 0x00, 0x01, 0x00];
-        let _ =
-            self.scsi
-                .as_mut()
-                .execute(&start, crate::scsi::DataDirection::None, &mut buf, 5_000);
-        std::thread::sleep(std::time::Duration::from_millis(2000));
-
-        if self
-            .scsi
-            .as_mut()
-            .execute(&tur, crate::scsi::DataDirection::None, &mut buf, 5_000)
-            .is_ok()
-        {
-            return Ok(());
-        }
-
-        // 2. Eject cycle — clears MT1959 LibreDrive stuck state.
-        // After eject, TUR returning "Not Ready — tray open" (sense key 2)
-        // counts as success: the drive is functional, just needs disc reinserted.
-        self.unlock_tray();
-        let eject = [SCSI_START_STOP_UNIT, 0x00, 0x00, 0x00, 0x02, 0x00];
-        let _ =
-            self.scsi
-                .as_mut()
-                .execute(&eject, crate::scsi::DataDirection::None, &mut buf, 30_000);
-        std::thread::sleep(std::time::Duration::from_millis(2000));
-
-        match self
-            .scsi
-            .as_mut()
-            .execute(&tur, crate::scsi::DataDirection::None, &mut buf, 5_000)
-        {
-            Ok(_) => return Ok(()),
-            Err(Error::ScsiError { sense_key: 2, .. }) => return Ok(()), // tray open = valid
-            _ => {}
-        }
-
-        // 3. If still stuck and we have a profile, try re-init
-        if self.driver.is_some() {
-            self.init()?;
-            std::thread::sleep(std::time::Duration::from_millis(1000));
-            match self.scsi.as_mut().execute(
-                &tur,
-                crate::scsi::DataDirection::None,
-                &mut buf,
-                5_000,
-            ) {
-                Ok(_) => return Ok(()),
-                Err(Error::ScsiError { sense_key: 2, .. }) => return Ok(()),
-                _ => {}
-            }
-        }
-
-        Err(Error::DeviceResetFailed {
-            path: self.device_path.clone(),
-        })
-    }
-
     pub fn platform_name(&self) -> &str {
         match self.platform {
             Some(ref p) => p.name(),
@@ -512,22 +420,38 @@ impl Drive {
     /// Read sectors from the disc. Single-shot — no inline retries, no
     /// SCSI reset.
     ///
-    /// `recovery=true` bumps the per-CDB timeout to 30 s for the
-    /// `Disc::patch` pass; `recovery=false` uses 1.5 s for `Disc::copy`'s
-    /// fast skip-forward sweep. On any failure returns `Err(DiscRead)`
-    /// immediately. The orchestration layer (`Disc::patch`'s outer loop
-    /// for the patch pass, `DiscStream`'s adaptive batch halving for the
-    /// stream path) handles retries.
+    /// `recovery=true` uses [`crate::scsi::READ_RECOVERY_TIMEOUT_MS`] (60 s,
+    /// matches sg_dd) for the `Disc::patch` pass; `recovery=false` uses
+    /// [`crate::scsi::READ_TIMEOUT_MS`] (30 s, matches the kernel's
+    /// `/sys/block/sr*/device/timeout` default) for `Disc::copy`'s fast
+    /// skip-forward sweep. Both budgets are generous enough that the drive
+    /// can finish ECC recovery on a marginal sector — pre-0.13.21 this was
+    /// 1.5 s on the fast path which forced the kernel mid-layer to time
+    /// out and escalate while we waited anyway. On any failure returns
+    /// `Err(DiscRead)` immediately; orchestration (`Disc::patch` multi-pass,
+    /// `DiscStream` adaptive batch halving) handles retry policy.
     ///
     /// Inline retry phases (5× gentle + reset+reopen + 5× more) were
     /// removed in 0.13.6. Per
-    /// `(internal)/postmortems/2026-04-25-stop-wedge-and-zero-kbs.md`,
+    /// the stop-wedge postmortem (2026-04-25),
     /// the inline reset on the LG BU40N (Initio bridge) wedged drive
     /// firmware without ever recovering a sector. The remaining recovery
     /// layers (Disc::patch multi-pass, DiscStream batch halving) do not
     /// touch the wedge-prone reset path.
     pub fn read(&mut self, lba: u32, count: u16, buf: &mut [u8], recovery: bool) -> Result<usize> {
-        let timeout_ms = if recovery { 30_000 } else { 1_500 };
+        let timeout_ms = if recovery {
+            crate::scsi::READ_RECOVERY_TIMEOUT_MS
+        } else {
+            crate::scsi::READ_TIMEOUT_MS
+        };
+        tracing::debug!(
+            target: "freemkv::drive",
+            lba,
+            count,
+            recovery,
+            timeout_ms,
+            "Drive::read enter"
+        );
         let cdb = [
             crate::scsi::SCSI_READ_10,
             0x00,
@@ -549,7 +473,22 @@ impl Drive {
         ) {
             Ok(result) => Ok(result.bytes_transferred),
             Err(Error::Halted) => Err(Error::Halted),
-            Err(_) => Err(Error::DiscRead { sector: lba as u64 }),
+            Err(e) => {
+                let (status, sense) = extract_scsi_context(&e);
+                tracing::warn!(
+                    target: "freemkv::drive",
+                    lba,
+                    count,
+                    inner_error = %e,
+                    scsi_status = status,
+                    "Drive::read checked_exec failed"
+                );
+                Err(Error::DiscRead {
+                    sector: lba as u64,
+                    status: Some(status),
+                    sense,
+                })
+            }
         }
     }
 
@@ -660,21 +599,21 @@ impl SectorReader for Drive {
     ) -> Result<usize> {
         self.read(lba, count, buf, recovery)
     }
+
+    fn set_speed(&mut self, kbs: u16) {
+        Drive::set_speed(self, kbs);
+    }
 }
 
-/// Find all optical drives connected to this system.
-/// Returns opened Drive objects ready for use.
-pub fn find_drives() -> Vec<Drive> {
+/// Find the first optical drive on this system and open it.
+///
+/// For just listing drives without opening (e.g. UI sidebar), use
+/// `scsi::list_drives()` — that returns `DriveInfo` (path + identity)
+/// without the cost of running every drive's profile + identity probe.
+pub fn find_drive() -> Option<Drive> {
     discover_drives()
         .into_iter()
-        .filter_map(|(path, _)| Drive::open(std::path::Path::new(&path)).ok())
-        .collect()
-}
-
-/// Find the first optical drive.
-/// Returns an opened Drive ready for use.
-pub fn find_drive() -> Option<Drive> {
-    find_drives().into_iter().next()
+        .find_map(|(path, _)| Drive::open(std::path::Path::new(&path)).ok())
 }
 
 /// Halt-aware sleep primitive — wakes within ~100 ms of `halt` flipping

src/error.rs

@@ -155,10 +155,24 @@ pub enum Error {
     },
 
     // SCSI (4xxx)
+    /// SCSI command failed.
+    ///
+    /// `opcode` is the failing CDB byte 0. `status` is the raw SCSI
+    /// status byte: `0x02` = CHECK CONDITION (drive replied with sense
+    /// data), `0xFF` = libfreemkv-synthesised sentinel meaning "no SCSI
+    /// status delivered" (kernel timeout, USB bridge wedge, IOKit
+    /// service failure). `sense` carries the drive's SPC-4 sense triple
+    /// when the drive replied; `None` for transport-layer failures.
+    ///
+    /// Recommended dispatch (callers shouldn't pattern-match raw
+    /// fields):
+    ///   - [`Error::is_scsi_transport_failure`] — bail; bridge/transport wedge
+    ///   - [`Error::is_marginal_read`] — drive said this read was marginal; smaller block may recover
+    ///   - [`Error::scsi_sense`] — borrow the sense triple for finer routing ([`ScsiSense::is_medium_error`] etc.)
     ScsiError {
         opcode: u8,
         status: u8,
-        sense_key: u8,
+        sense: Option<crate::scsi::ScsiSense>,
     },
 
     // I/O (5xxx)
@@ -169,6 +183,8 @@ pub enum Error {
     // Disc format (6xxx)
     DiscRead {
         sector: u64,
+        status: Option<u8>,
+        sense: Option<crate::scsi::ScsiSense>,
     },
     /// Drive was halted by caller.
     Halted,
@@ -363,19 +379,46 @@ impl std::fmt::Display for Error {
             Error::ScsiError {
                 opcode,
                 status,
-                sense_key,
-            } => {
-                write!(
+                sense,
+            } => match sense {
+                Some(s) => write!(
                     f,
-                    "E{}: 0x{:02x}/0x{:02x}/0x{:02x}",
+                    "E{}: 0x{:02x}/0x{:02x}/0x{:02x}/0x{:02x}/0x{:02x}",
                     self.code(),
                     opcode,
                     status,
-                    sense_key
-                )
-            }
+                    s.sense_key,
+                    s.asc,
+                    s.ascq,
+                ),
+                None => write!(f, "E{}: 0x{:02x}/0x{:02x}", self.code(), opcode, status,),
+            },
             Error::IoError { source } => write!(f, "E{}: {}", self.code(), source),
-            Error::DiscRead { sector } => write!(f, "E{}: {}", self.code(), sector),
+            Error::DiscRead {
+                sector,
+                status,
+                sense,
+            } => match (status, sense) {
+                (Some(st), Some(s)) => write!(
+                    f,
+                    "E{}: {} 0x{:02x}/0x{:02x}/0x{:02x}",
+                    self.code(),
+                    sector,
+                    st,
+                    s.sense_key,
+                    s.asc,
+                ),
+                (Some(st), None) => write!(f, "E{}: {} 0x{:02x}", self.code(), sector, st,),
+                (None, Some(s)) => write!(
+                    f,
+                    "E{}: {} 0x{:02x}/0x{:02x}",
+                    self.code(),
+                    sector,
+                    s.sense_key,
+                    s.asc,
+                ),
+                (None, None) => write!(f, "E{}: {}", self.code(), sector),
+            },
             Error::Halted => write!(f, "E{}", self.code()),
             Error::UdfNotFound { path } => write!(f, "E{}: {}", self.code(), path),
             Error::DiscTitleRange { index, count } => {
@@ -438,6 +481,80 @@ impl From<Error> for std::io::Error {
 /// Convenience alias for `Result<T, Error>`.
 pub type Result<T> = std::result::Result<T, Error>;
 
+impl Error {
+    /// Borrow the drive-returned SPC-4 sense triple if this error is a
+    /// [`Error::ScsiError`] carrying sense data. `None` for any other
+    /// variant **and** for `ScsiError`s that represent a transport-layer
+    /// failure (where the device never delivered a SCSI status reply, so
+    /// no sense data exists).
+    pub fn scsi_sense(&self) -> Option<&crate::scsi::ScsiSense> {
+        match self {
+            Error::ScsiError { sense: Some(s), .. } => Some(s),
+            Error::DiscRead { sense: Some(s), .. } => Some(s),
+            _ => None,
+        }
+    }
+
+    /// True if this is a [`Error::ScsiError`] representing a transport-layer
+    /// failure — kernel timeout, USB bridge wedge, IOKit service error.
+    /// The device never delivered a SCSI status reply, so there is no
+    /// sense data to inspect; retrying typically requires physical
+    /// intervention (replug).
+    pub fn is_scsi_transport_failure(&self) -> bool {
+        matches!(
+            self,
+            Error::ScsiError {
+                status: crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE,
+                ..
+            }
+        ) || matches!(
+            self,
+            Error::DiscRead {
+                status: Some(crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE),
+                ..
+            }
+        )
+    }
+
+    /// True if this error indicates bridge degradation — the SCSI status
+    /// is neither GOOD (0x00), CHECK CONDITION (0x02), nor transport failure
+    /// (0xFF). Observed on the Initio INIC-1618L USB bridge preceding a full
+    /// crash: the bridge firmware returns non-standard status bytes (e.g.
+    /// 0x04, 0x05) with empty sense data. The caller should cool down
+    /// (10 s pause) and retry rather than hammering the bridge.
+    pub fn is_bridge_degradation(&self) -> bool {
+        let status = match self {
+            Error::ScsiError { status, .. } => *status,
+            Error::DiscRead { status, .. } => status.unwrap_or(0),
+            _ => return false,
+        };
+        status != crate::scsi::SCSI_STATUS_GOOD
+            && status != crate::scsi::SCSI_STATUS_CHECK_CONDITION
+            && status != crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE
+    }
+
+    /// True if the underlying SCSI failure is a *marginal read* — the
+    /// drive returned an error category in which smaller-granularity
+    /// retries can sometimes recover the data:
+    ///
+    ///   - MEDIUM ERROR (sense key 3) — canonical bad-sector signal
+    ///   - ABORTED COMMAND (sense key B) — transient; retry usually works
+    ///   - RECOVERED ERROR (sense key 1) / NO SENSE (sense key 0) — not
+    ///     classified as fatal; treat as recoverable
+    ///
+    /// Returns `false` for transport failures (no sense data delivered),
+    /// HARDWARE ERROR, DATA PROTECT, UNIT ATTENTION, NOT READY, ILLEGAL
+    /// REQUEST, BLANK CHECK, kernel `IoError`, and any non-SCSI variant.
+    /// Caller-agnostic predicate — describes a property of the *error*,
+    /// not what one specific call site should do with it. Used by
+    /// `Disc::copy`'s hysteresis dispatch.
+    pub fn is_marginal_read(&self) -> bool {
+        self.scsi_sense()
+            .map(crate::scsi::ScsiSense::is_marginal)
+            .unwrap_or(false)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     //! Smoke tests for the error code → variant mapping. Each new variant

src/lib.rs

@@ -103,7 +103,7 @@ pub mod verify;
 pub use drive::capture::{
     CapturedFeature, DriveCapture, capture_drive_data, mask_bytes, mask_string,
 };
-pub use drive::{Drive, DriveStatus, find_drive, find_drives};
+pub use drive::{Drive, DriveStatus, find_drive};
 
 // ─── Errors ─────────────────────────────────────────────────────────────────
 //
@@ -134,9 +134,10 @@ pub use decrypt::{DecryptKeys, decrypt_sectors};
 // background. The codec / channel / resolution enums are the canonical
 // structured representation; never compare against display strings.
 pub use disc::{
-    AacsState, AudioChannels, AudioStream, Clip, Codec, ColorSpace, ContentFormat, Disc,
-    DiscFormat, DiscId, DiscTitle, Extent, FrameRate, HdrFormat, KeySource, LabelPurpose,
+    AacsState, AudioChannels, AudioStream, Clip, Codec, ColorSpace, ContentFormat, DamageSeverity,
+    Disc, DiscFormat, DiscId, DiscTitle, Extent, FrameRate, HdrFormat, KeySource, LabelPurpose,
     LabelQualifier, Resolution, SampleRate, ScanOptions, Stream, SubtitleStream, VideoStream,
+    classify_damage,
 };
 
 // ─── Streams ────────────────────────────────────────────────────────────────
@@ -168,7 +169,7 @@ pub use mux::{InputOptions, StreamUrl, input, output, parse_url};
 // out-of-tree platform backends. `SectorReader` lets callers feed any byte
 // source (test harness, network image, SMB share) into the disc scan
 // pipeline; `FileSectorReader` is the standard ISO-on-disk implementation.
-pub use scsi::{DriveInfo, ScsiTransport, drive_has_disc, list_drives};
+pub use scsi::{DriveInfo, ScsiSense, ScsiTransport, drive_has_disc, list_drives};
 pub use sector::{FileSectorReader, SectorReader};
 pub use speed::DriveSpeed;
 pub use udf::{UdfFs, read_filesystem};

src/mux/disc.rs

@@ -6,6 +6,7 @@
 //! Read-only. For disc→ISO (raw sector copy), use `Disc::copy()`.
 
 use crate::disc::{Disc, DiscTitle, Extent};
+use crate::drive::extract_scsi_context;
 use crate::event::{BatchSizeReason, Event, EventKind};
 use crate::sector::SectorReader;
 use std::io;
@@ -317,7 +318,18 @@ impl DiscStream {
                     self.current_offset += 1;
                     break;
                 } else {
-                    return Err(crate::error::Error::DiscRead { sector: lba as u64 }.into());
+                    let err = self
+                        .reader
+                        .read_sectors(lba, sectors, &mut self.read_buf[..2048], false)
+                        .err();
+                    let (status, sense) =
+                        err.as_ref().map(extract_scsi_context).unwrap_or((0, None));
+                    return Err(crate::error::Error::DiscRead {
+                        sector: lba as u64,
+                        status: Some(status),
+                        sense,
+                    }
+                    .into());
                 }
             }
 

src/platform/mt1959/mod.rs

@@ -96,8 +96,8 @@ impl Mt1959 {
         if result.bytes_transferred != expected {
             return Err(Error::ScsiError {
                 opcode: SCSI_READ_BUFFER,
-                status: 0xFF,
-                sense_key: 0,
+                status: crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
             });
         }
         Ok(result.bytes_transferred)
@@ -169,8 +169,8 @@ impl Mt1959 {
         }
         Err(Error::ScsiError {
             opcode: SCSI_READ_BUFFER,
-            status: 0xFF,
-            sense_key: 0,
+            status: crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE,
+            sense: None,
         })
     }
 
@@ -275,8 +275,8 @@ impl Mt1959 {
             {
                 return Err(Error::ScsiError {
                     opcode: SCSI_READ_BUFFER,
-                    status: 0xFF,
-                    sense_key: 0,
+                    status: crate::scsi::SCSI_STATUS_TRANSPORT_FAILURE,
+                    sense: None,
                 });
             }
             addr = addr.wrapping_add(PROBE_STEP);

src/progress.rs

@@ -47,6 +47,9 @@ pub struct PassProgress {
     /// Cumulative bytes confirmed clean (`Finished` mapfile state) across
     /// every pass run on this rip. Doesn't change across pass boundaries.
     pub bytes_good_total: u64,
+    /// Cumulative bytes marked bad (`NonTrimmed` + `NonScraped` +
+    /// `Unreadable`) across every pass run on this rip.
+    pub bytes_bad_total: u64,
     /// Total disc capacity in bytes. Constant.
     pub bytes_total_disc: u64,
 }

src/scsi/linux.rs

@@ -1,11 +1,23 @@
-//! Linux SCSI transport via async sg write/poll/read.
+//! Linux SCSI transport via synchronous blocking SG_IO ioctl.
 //!
-//! Uses the sg driver's asynchronous interface instead of the blocking
-//! SG_IO ioctl. Commands are submitted via write(), waited on via
-//! poll() with a hard timeout, and completed via read(). If poll()
-//! times out, the fd is abandoned (closed in a background thread) and
-//! a fresh fd is opened. This gives us true user-controlled timeouts
-//! that the kernel's USB error recovery cannot override.
+//! `execute()` is one syscall: `ioctl(fd, SG_IO, &hdr)` blocks until the
+//! kernel completes the command (success, error, or its own timeout).
+//! No userspace abort, no fd close+reopen, no SG_SCSI_RESET escalation —
+//! the kernel SCSI mid-layer's `scsi_eh.rst` ladder
+//! (ABORT TASK → LUN RESET → BUS RESET → HOST RESET) runs internally
+//! when `hdr.timeout` expires, and by the time the ioctl returns the
+//! kernel has already done what it can.
+//!
+//! This matches what every reference project does: MakeMKV (8 s sync
+//! ioctl), sg_dd (60 s sync ioctl), the kernel default for SCSI block
+//! devices (30 s `/sys/.../timeout`). See
+//! the SCSI architecture audit (2026-04-26) for the full primary-source
+//! references.
+//!
+//! Pre-0.13.20 we ran an async `write() + poll(1.5s) + close-on-timeout +
+//! bg reopen` pattern. That abandoned slow-but-alive commands faster than
+//! the drive could drain its internal queue, deepening the wedge
+//! pattern on the LG BU40N. Reverted in 0.13.20.
 
 use super::{DataDirection, ScsiResult, ScsiTransport};
 use crate::error::{Error, Result};
@@ -45,33 +57,22 @@ struct sg_io_hdr {
 }
 
 // Compile-time validation: sg_io_hdr must match the kernel's layout.
-// 64 bytes on 64-bit, 44 bytes on 32-bit (pointer-size dependent).
+// 88 bytes on 64-bit, 64 bytes on 32-bit (pointer-size dependent).
 #[cfg(target_pointer_width = "64")]
 const _: () = assert!(std::mem::size_of::<sg_io_hdr>() == 88);
 #[cfg(target_pointer_width = "32")]
 const _: () = assert!(std::mem::size_of::<sg_io_hdr>() == 64);
 
 pub struct SgIoTransport {
-    fd: i32,
+    pub fd: i32,
     device_path: std::path::PathBuf,
-    /// Background-recovered fd. After a poll timeout `execute()` spawns a
-    /// thread that closes `self.fd` and opens a fresh fd; the new fd is
-    /// stored here. The next call to `execute()` swaps it into `self.fd`.
-    /// `-1` means no recovery is ready (or the recovery open failed). See
-    /// RIP_DESIGN.md §7 for the design rationale.
-    fd_recovery: std::sync::Arc<std::sync::atomic::AtomicI32>,
+    pub fd_recovery: std::sync::Arc<std::sync::atomic::AtomicI32>,
 }
 
-// SgIoTransport's contained types (i32, PathBuf, Arc<AtomicI32>) are all
-// Send; the auto-derived Send is intentional. Sync is NOT — callers must
-// hold &mut for execute(), which the trait object dispatch enforces.
-
 impl SgIoTransport {
-    /// Open a SCSI device for use. Resets the drive first to ensure
-    /// a known good state, then opens a fresh fd for commands.
+    /// Open a SCSI device for use.
     pub fn open(device: &Path) -> Result<Self> {
         let device = Self::resolve_to_sg(device);
-        Self::reset(&device)?;
         let c_path = Self::to_c_path(&device);
         let fd = unsafe {
             libc::open(
@@ -105,48 +106,7 @@ impl SgIoTransport {
     /// STOP+START UNIT. Both escalations were tried in 0.13.0–0.13.5
     /// against the LG BU40N (Initio USB-SATA bridge); both failed to
     /// recover wedged drives and made the wedge worse — see
-    /// (internal)/postmortems/2026-04-25-bu40n-wedge-recovery.md.
-    /// If the drive is genuinely unresponsive, the next workload command
-    /// fails naturally and the caller surfaces a "physical reconnect
-    /// required" prompt. Software has no path back from a wedged Initio
-    /// bridge — only physical replug clears it.
-    pub fn reset(device: &Path) -> Result<()> {
-        let c_path = Self::to_c_path(device);
-
-        // open + close — make the kernel cancel any SG_IO commands queued
-        // against a previous fd that didn't close cleanly.
-        let probe_fd = unsafe {
-            libc::open(
-                c_path.as_ptr() as *const libc::c_char,
-                libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
-            )
-        };
-        if probe_fd >= 0 {
-            unsafe { libc::close(probe_fd) };
-        }
-
-        // Let the kernel finish that cancellation before we reopen.
-        std::thread::sleep(std::time::Duration::from_secs(2));
-
-        // Fresh fd just to send the unlock command, then close.
-        let fd = unsafe {
-            libc::open(
-                c_path.as_ptr() as *const libc::c_char,
-                libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
-            )
-        };
-        if fd < 0 {
-            return Self::open_error(device);
-        }
-
-        // ALLOW MEDIUM REMOVAL — clear any tray lock left by a killed
-        // process whose Drop never ran. Best-effort; ignore result.
-        let _ = Self::raw_command(fd, &[0x1E, 0, 0, 0, 0, 0], 3_000);
-
-        unsafe { libc::close(fd) };
-        Ok(())
-    }
-
+    /// the BU40N wedge recovery postmortem (2026-04-25).
     fn open_error<T>(device: &Path) -> Result<T> {
         let err = std::io::Error::last_os_error();
         Err(if err.kind() == std::io::ErrorKind::PermissionDenied {
@@ -161,8 +121,7 @@ impl SgIoTransport {
     }
 
     /// Send a raw SCSI command on an fd. Used by reset() before the
-    /// transport is constructed. Uses synchronous SG_IO — fine for
-    /// short commands (TUR, PREVENT MEDIUM REMOVAL, START/STOP).
+    /// transport is constructed.
     fn raw_command(fd: i32, cdb: &[u8], timeout_ms: u32) -> std::result::Result<(), ()> {
         let mut sense = [0u8; 32];
         let mut hdr: sg_io_hdr = unsafe { std::mem::zeroed() };
@@ -178,7 +137,7 @@ impl SgIoTransport {
         hdr.flags = SG_FLAG_Q_AT_HEAD;
 
         let ret = unsafe { libc::ioctl(fd, SG_IO as _, &mut hdr as *mut sg_io_hdr) };
-        if ret < 0 || hdr.status != 0 {
+        if ret < 0 || hdr.status != 0 || hdr.host_status != 0 || hdr.driver_status != 0 {
             Err(())
         } else {
             Ok(())
@@ -223,36 +182,41 @@ impl SgIoTransport {
 impl Drop for SgIoTransport {
     fn drop(&mut self) {
         if self.fd >= 0 {
-            // Unlock tray before closing — don't leave it locked
+            // Unlock tray before closing — don't leave it locked.
             let _ = Self::raw_command(self.fd, &[0x1E, 0, 0, 0, 0, 0], 3_000);
             unsafe { libc::close(self.fd) };
         }
-        // Drain any background-recovered fd so it doesn't leak.
-        let recovered = self
-            .fd_recovery
-            .swap(-1, std::sync::atomic::Ordering::Acquire);
-        if recovered >= 0 {
-            unsafe { libc::close(recovered) };
-        }
     }
 }
 
 impl ScsiTransport for SgIoTransport {
-    /// Execute a SCSI command with an enforceable timeout.
+    /// Execute a SCSI command via synchronous blocking SG_IO.
     ///
-    /// Uses the sg driver's async write/poll/read interface:
-    /// 1. write() submits the command — returns immediately
-    /// 2. poll() waits for completion — respects our timeout exactly
-    /// 3. read() retrieves the result — copies data to caller's buffer
+    /// One syscall: `ioctl(fd, SG_IO, &hdr)`. The kernel honors
+    /// `hdr.timeout` and runs its own ABORT TASK → LUN RESET → BUS
+    /// RESET → HOST RESET escalation if the device times out (per
+    /// `Documentation/scsi/scsi_eh.rst`). By the time this returns,
+    /// the kernel has done its recovery work.
     ///
-    /// If poll() times out, the pending command is abandoned: the old fd
-    /// is closed in a background thread (may block while kernel finishes
-    /// the USB transfer) and a fresh fd is opened. The caller sees a
-    /// normal SCSI error and can retry.
+    /// Errors we surface to caller (any of these = command failed):
     ///
-    /// Without SG_FLAG_DIRECT_IO, the kernel uses internal buffers for
-    /// DMA and copies to userspace during read(). On timeout (no read),
-    /// the caller's buffer is untouched — safe to return immediately.
+    ///   - ioctl returned -1 → `Error::IoError` (kernel-level failure)
+    ///   - `hdr.host_status` != 0 OR `(hdr.driver_status & ~DRIVER_SENSE)` != 0
+    ///     → `Error::ScsiError { status: 0xFF, sense_key: 0, asc: 0, ascq: 0 }`
+    ///     (real transport-layer failure: kernel timeout, bridge wedge, bus error)
+    ///   - `hdr.status` != 0 (typically `0x02` CHECK CONDITION) →
+    ///     `Error::ScsiError { status, sense_key, asc, ascq }` carrying the
+    ///     drive's full SPC-4 sense triple. Callers route on
+    ///     `is_medium_error()`, `is_unit_attention()`, etc.
+    ///
+    /// Note: SG's `DRIVER_SENSE` (0x08) bit indicates *sense data is
+    /// attached* — it's set on every CHECK CONDITION reply. It is **not**
+    /// a transport failure; pre-0.13.23 we conflated it with one and
+    /// silently lost every drive-reported error reason. The mask in the
+    /// transport-error check below is the fix.
+    ///
+    /// Caller's `data` buffer is mutated only on success; partial
+    /// transfers are reported via `bytes_transferred = data.len() - resid`.
     fn execute(
         &mut self,
         cdb: &[u8],
@@ -272,53 +236,38 @@ impl ScsiTransport for SgIoTransport {
             "SgIoTransport::execute"
         );
 
-        // Recover from a prior timeout: if a background reopen produced a
-        // fresh fd, swap it in. If recovery is still pending (-1), the
-        // background thread hasn't finished — return DeviceNotFound and let
-        // the caller's retry loop come back later.
-        if self.fd < 0 {
-            let recovered = self
-                .fd_recovery
-                .swap(-1, std::sync::atomic::Ordering::Acquire);
-            if recovered >= 0 {
-                tracing::trace!(
-                    target: "freemkv::scsi",
-                    phase = "recovery_swap_ok",
-                    new_fd = recovered,
-                    "fd_recovery delivered fresh fd"
-                );
-                self.fd = recovered;
-            } else {
-                tracing::trace!(
-                    target: "freemkv::scsi",
-                    phase = "recovery_pending",
-                    elapsed_us = exec_t0.elapsed().as_micros() as u64,
-                    "fd_recovery still pending → DeviceNotFound"
-                );
-                return Err(Error::DeviceNotFound {
-                    path: self.device_path.display().to_string(),
-                });
+        // Check if a background recovery has produced a new fd.
+        let recovered = self
+            .fd_recovery
+            .swap(-1, std::sync::atomic::Ordering::Acquire);
+        if recovered >= 0 {
+            // Close the old fd if it's still valid.
+            if self.fd >= 0 {
+                unsafe { libc::close(self.fd) };
             }
+            self.fd = recovered;
+        } else if self.fd < 0 {
+            return Err(Error::DeviceNotFound {
+                path: self.device_path.display().to_string(),
+            });
         }
 
-        let mut sense = [0u8; 32];
+        if data.len() > u32::MAX as usize {
+            return Err(Error::ScsiError {
+                opcode: cdb[0],
+                status: super::SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
+            });
+        }
 
         let dxfer_direction = match direction {
             DataDirection::None => SG_DXFER_NONE,
             DataDirection::FromDevice => SG_DXFER_FROM_DEV,
             DataDirection::ToDevice => SG_DXFER_TO_DEV,
         };
-
-        if data.len() > u32::MAX as usize {
-            return Err(Error::ScsiError {
-                opcode: cdb[0],
-                status: 0xFF,
-                sense_key: 0,
-            });
-        }
-
         let cmd_len = cdb.len().min(16) as u8;
 
+        let mut sense = [0u8; 32];
         let mut hdr: sg_io_hdr = unsafe { std::mem::zeroed() };
         hdr.interface_id = b'S' as i32;
         hdr.dxfer_direction = dxfer_direction;
@@ -331,193 +280,116 @@ impl ScsiTransport for SgIoTransport {
         hdr.timeout = timeout_ms;
         hdr.flags = SG_FLAG_Q_AT_HEAD;
 
-        // Submit command asynchronously via write()
-        let hdr_size = std::mem::size_of::<sg_io_hdr>();
-        let write_t0 = std::time::Instant::now();
-        let wr = unsafe {
-            libc::write(
-                self.fd,
-                &hdr as *const sg_io_hdr as *const libc::c_void,
-                hdr_size,
-            )
-        };
-        let write_elapsed_us = write_t0.elapsed().as_micros() as u64;
-        if wr < 0 {
+        // The single blocking syscall. Returns when the device responds,
+        // when the kernel's timeout fires, or when the kernel's error
+        // recovery completes its escalation. On a healthy read this is
+        // <100 ms; on a slow-recovery bad sector it can be tens of
+        // seconds; on a hung drive it returns at `timeout_ms` with
+        // `host_status` flagged.
+        let ret = unsafe { libc::ioctl(self.fd, SG_IO as _, &mut hdr as *mut sg_io_hdr) };
+        let exec_elapsed_ms = exec_t0.elapsed().as_millis() as u64;
+
+        if ret < 0 {
             let errno = std::io::Error::last_os_error();
             tracing::trace!(
                 target: "freemkv::scsi",
-                phase = "write_err",
+                phase = "ioctl_err",
                 opcode = opcode,
                 errno = errno.raw_os_error().unwrap_or(0),
-                write_elapsed_us,
-                "sg write() returned <0"
+                exec_elapsed_ms,
+                "ioctl(SG_IO) returned <0"
             );
             return Err(Error::IoError { source: errno });
         }
-        tracing::trace!(
-            target: "freemkv::scsi",
-            phase = "write_ok",
-            opcode = opcode,
-            wr,
-            write_elapsed_us,
-            "sg write() submitted"
-        );
 
-        // Wait for completion with enforceable timeout.
-        // Retry on EINTR (signal interrupted poll) with remaining time.
-        let poll_t0 = std::time::Instant::now();
-        let deadline = poll_t0 + std::time::Duration::from_millis(timeout_ms as u64);
-        let pr = loop {
-            let remaining = deadline
-                .saturating_duration_since(std::time::Instant::now())
-                .as_millis() as i32;
-            if remaining <= 0 {
-                break 0; // expired
-            }
-            let mut pfd = libc::pollfd {
-                fd: self.fd,
-                events: libc::POLLIN,
-                revents: 0,
-            };
-            let ret = unsafe { libc::poll(&mut pfd, 1, remaining) };
-            if ret >= 0 || std::io::Error::last_os_error().kind() != std::io::ErrorKind::Interrupted
-            {
-                break ret;
-            }
-        };
-        let poll_elapsed_ms = poll_t0.elapsed().as_millis() as u64;
-        tracing::trace!(
-            target: "freemkv::scsi",
-            phase = "poll_done",
-            opcode = opcode,
-            pr,
-            poll_elapsed_ms,
-            timeout_ms,
-            "poll() returned"
-        );
-
-        if pr <= 0 {
-            // Timeout (0) or fatal poll error (-1). Command is still pending
-            // in the kernel. Per RIP_DESIGN.md §4(b)/§7: close + reopen run
-            // in a background thread so the main thread is never blocked
-            // beyond the poll() budget. The recovered fd is published to
-            // `fd_recovery`; the next call to execute() picks it up.
-            let old_fd = self.fd;
-            self.fd = -1;
-            let c_path = Self::to_c_path(&self.device_path);
-            let recovery = self.fd_recovery.clone();
+        // Transport-level failure (kernel timeout, USB bridge wedge,
+        // bus error). `hdr.status` may still be zero — the SCSI device
+        // never got to send a status byte. Surface as 0xFF so callers
+        // (e.g. `drive_has_disc`) can detect the wedge signature.
+        //
+        // 0.13.23: mask out `DRIVER_SENSE` (0x08) before treating
+        // `driver_status` as a transport failure. That bit is set on
+        // *every* CHECK CONDITION reply just to flag "sense data is
+        // attached in `sbp`" — it's not an error of its own. Pre-fix
+        // we collapsed every drive-reported error into a synthetic
+        // 0xFF wedge signature and discarded the sense data, which
+        // killed the rip's classification logic on damaged discs.
+        let driver_status_real = hdr.driver_status & !super::DRIVER_SENSE;
+        if hdr.host_status != 0 || driver_status_real != 0 {
             tracing::trace!(
                 target: "freemkv::scsi",
-                phase = "timeout_spawn_recovery",
+                phase = "transport_err",
                 opcode = opcode,
-                old_fd,
-                exec_elapsed_ms = exec_t0.elapsed().as_millis() as u64,
-                "poll timeout — spawning bg close+open"
+                host_status = hdr.host_status,
+                driver_status = hdr.driver_status,
+                status = hdr.status,
+                exec_elapsed_ms,
+                "transport-level failure (timeout / bridge wedge)"
             );
+
+            // Spawn recovery: close old fd, open new one in background.
+            // This prevents the main thread from blocking on close() while
+            // the kernel finishes the previous ioctl.
+            let old_fd = self.fd;
+            self.fd = -1;
+            let path = self.device_path.clone();
+            let recovery = self.fd_recovery.clone();
+
             std::thread::spawn(move || {
-                // Close blocks until the kernel finishes/aborts the
-                // abandoned command. Then we open a fresh fd. Both happen
-                // off the main thread.
-                let close_t0 = std::time::Instant::now();
-                unsafe { libc::close(old_fd) };
-                let close_ms = close_t0.elapsed().as_millis() as u64;
-                let open_t0 = std::time::Instant::now();
+                if old_fd >= 0 {
+                    unsafe { libc::close(old_fd) };
+                }
+            });
+
+            std::thread::spawn(move || {
+                let c_path = std::ffi::CString::new(path.as_os_str().as_encoded_bytes()).unwrap();
                 let new_fd = unsafe {
                     libc::open(
                         c_path.as_ptr() as *const libc::c_char,
                         libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
                     )
                 };
-                let open_ms = open_t0.elapsed().as_millis() as u64;
-                tracing::trace!(
-                    target: "freemkv::scsi",
-                    phase = "bg_recovery_done",
-                    old_fd,
-                    new_fd,
-                    close_ms,
-                    open_ms,
-                    "bg recovery thread completed close+open"
-                );
-                if new_fd >= 0 {
-                    let prev = recovery.swap(new_fd, std::sync::atomic::Ordering::Release);
-                    if prev >= 0 {
-                        // Stale recovery fd from a prior unclaimed attempt;
-                        // close it so it doesn't leak.
-                        unsafe { libc::close(prev) };
-                    }
-                } else {
-                    recovery.store(-1, std::sync::atomic::Ordering::Release);
-                }
+                recovery.store(new_fd, std::sync::atomic::Ordering::Release);
             });
 
             return Err(Error::ScsiError {
                 opcode: cdb[0],
-                status: 0xFF,
-                sense_key: 0,
+                status: super::SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
             });
         }
 
-        // Read response — copies data from kernel buffer to caller's buffer
-        let read_t0 = std::time::Instant::now();
-        let rd = unsafe {
-            libc::read(
-                self.fd,
-                &mut hdr as *mut sg_io_hdr as *mut libc::c_void,
-                hdr_size,
-            )
-        };
-        let read_elapsed_us = read_t0.elapsed().as_micros() as u64;
-        if rd < 0 {
-            tracing::trace!(
-                target: "freemkv::scsi",
-                phase = "read_err",
-                opcode = opcode,
-                read_elapsed_us,
-                exec_elapsed_ms = exec_t0.elapsed().as_millis() as u64,
-                "sg read() returned <0"
-            );
-            return Err(Error::IoError {
-                source: std::io::Error::last_os_error(),
-            });
-        }
-
-        let bytes_transferred = (data.len() as i32).saturating_sub(hdr.resid).max(0) as usize;
-
+        // SCSI-level failure: device responded, returned non-zero status
+        // (typically 0x02 CHECK CONDITION). Parse the full SPC-4 sense
+        // triple so callers can route on `ScsiSense::is_medium_error()`
+        // etc.
         if hdr.status != 0 {
-            let sense_key = if hdr.sb_len_wr >= 3 {
-                let response_code = sense[0] & 0x7F;
-                if response_code == 0x72 || response_code == 0x73 {
-                    // Descriptor format sense: sense key at byte 1
-                    sense[1] & 0x0F
-                } else {
-                    // Fixed format sense (0x70/0x71): sense key at byte 2
-                    sense[2] & 0x0F
-                }
-            } else {
-                0
-            };
+            let parsed = super::parse_sense(&sense, hdr.sb_len_wr);
             tracing::trace!(
                 target: "freemkv::scsi",
                 phase = "scsi_err",
                 opcode = opcode,
                 status = hdr.status,
-                sense_key,
-                exec_elapsed_ms = exec_t0.elapsed().as_millis() as u64,
+                sense_key = parsed.sense_key,
+                asc = parsed.asc,
+                ascq = parsed.ascq,
+                exec_elapsed_ms,
                 "SCSI status non-zero"
             );
             return Err(Error::ScsiError {
                 opcode: cdb[0],
                 status: hdr.status,
-                sense_key,
+                sense: Some(parsed),
             });
         }
 
+        let bytes_transferred = (data.len() as i32).saturating_sub(hdr.resid).max(0) as usize;
         tracing::trace!(
             target: "freemkv::scsi",
             phase = "ok",
             opcode = opcode,
             bytes_transferred,
-            exec_elapsed_ms = exec_t0.elapsed().as_millis() as u64,
+            exec_elapsed_ms,
             "execute() success"
         );
         Ok(ScsiResult {
@@ -535,31 +407,20 @@ impl ScsiTransport for SgIoTransport {
 // `/dev/sg0..15` probe when sysfs is unreadable (minimal containers).
 //
 // `drive_has_disc` issues a single TEST UNIT READY. On the wedge signature
-// (kernel returns status `0xff` with no sense) it escalates: SCSI bus reset
-// → if still wedged → USB device reset (`USBDEVFS_RESET`) → retry TUR.
-// Callers never see the escalation; if it fails too, surface
-// `DeviceResetFailed` so the caller can back off.
+// (kernel returns status `0xff` with no sense — synthesised by `execute()`
+// from a non-zero `host_status`) the error bubbles directly to the caller;
+// no in-library reset escalation. See the rationale block on
+// `drive_has_disc` below.
 
 /// SCSI peripheral type 5 = "CD-ROM device" (covers DVD, BD-ROM, BD-RE, etc.).
 /// Stored in `/sys/class/scsi_generic/sgN/device/type` as ASCII decimal.
 const SCSI_TYPE_OPTICAL: &str = "5";
 
-/// SCSI sense key 2 = "NOT READY". Sub-codes distinguish "medium not present"
-/// (no disc) from other not-ready states (loading, etc.); for poll-loop
-/// purposes any sense-key 2 means "no disc to act on".
-const SENSE_KEY_NOT_READY: u8 = 2;
-
 /// Maximum sg index probed in the fallback path when sysfs is unavailable.
 /// Linux assigns `/dev/sgN` sequentially per host adapter; 16 covers any
 /// realistic homelab (typical PERC + USB optical = ≤8 nodes).
 const SG_FALLBACK_MAX: u8 = 16;
 
-// SCSI INQUIRY field-offset constants previously lived here. They were
-// used by an in-process SCSI INQUIRY parse path that 0.13.6 retired in
-// favour of reading the kernel-cached sysfs identity (vendor/model/rev
-// under /sys/class/scsi_generic/sgN/device/). Removed to keep clippy
-// -D warnings clean.
-
 pub(super) fn list_drives() -> Vec<super::DriveInfo> {
     let mut out = Vec::new();
     let names = enumerate_sg_names();
@@ -579,8 +440,7 @@ pub(super) fn list_drives() -> Vec<super::DriveInfo> {
 
         // INQUIRY-only probe — open transport, run INQUIRY, drop. No
         // identify, no init, no firmware reset preamble's secondary
-        // commands beyond what `SgIoTransport::open` already does (one
-        // SCSI bus reset on the kernel SG fd, ~2 s).
+        // commands beyond what `SgIoTransport::open` already does.
         let info = match SgIoTransport::open(std::path::Path::new(&path)) {
             Ok(mut transport) => match super::inquiry(&mut transport) {
                 Ok(r) => super::DriveInfo {
@@ -646,8 +506,8 @@ fn enumerate_sg_names() -> Vec<String> {
             let type_path = format!("/sys/class/scsi_generic/{name}/device/type");
             match std::fs::read_to_string(&type_path) {
                 Ok(s) if s.trim() == SCSI_TYPE_OPTICAL => names.push(name),
-                Ok(_) => {}                 // not optical
-                Err(_) => names.push(name), // sysfs unreadable — let INQUIRY decide
+                Ok(_) => {} // not optical
+                Err(_) => {}
             }
         }
     } else {
@@ -664,50 +524,64 @@ fn enumerate_sg_names() -> Vec<String> {
     names
 }
 
-/// `drive_has_disc` = single TEST UNIT READY. Any error (including our
-/// synthesised wedge signature, `ScsiError { status: 0xFF }`, when
-/// `execute()` times out) bubbles straight up to the caller.
-///
-/// ## No in-library wedge recovery — and why
-///
-/// Versions 0.13.1 – 0.13.3 layered `scsi::reset()` + `scsi::usb_reset()`
-/// (`USBDEVFS_RESET`) escalation inside `drive_has_disc`. Production
-/// testing on the LG BU40N USB BD-RE showed all three userspace recovery
-/// ladders succeed at the USB transport level (the kernel logs
-/// `usb 3-2: reset high-speed USB device`, the device re-authorises
-/// and re-attaches on a fresh `scsi_host`) **but the drive firmware
-/// below the USB bridge stays locked** — no LUN ever enumerates, TUR
-/// never succeeds, /dev/sg* never reappears. Physical power-cycle
-/// (unplug-replug or host reboot) is the only recovery.
-///
-/// Methods tried and discarded:
-///  - `SG_SCSI_RESET` (device-level SCSI bus reset)
-///  - `STOP UNIT` / `START UNIT` CDB pair
-///  - `USBDEVFS_RESET` ioctl on `/dev/bus/usb/BBB/DDD`
-///  - `/sys/bus/usb/devices/<port>/authorized` 0→1 toggle
-///  - `/sys/bus/usb/drivers/usb-storage/{unbind,bind}` driver rebind
-///  - Forced `echo "- - -" > /sys/class/scsi_host/hostN/scan`
-///
-/// Rolled back in 0.13.4. Callers (autorip, CLI) surface the error
-/// directly and prompt the user to physically reconnect the drive.
-/// If a future hardware class is found where USB-layer recovery
-/// actually works, the escalation belongs here, gated on the wedge
-/// signature — see git tag `v0.13.3` for the full implementation.
+/// Send TEST UNIT READY directly — no transport, no reset, no side effects.
 pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
-    let mut transport = SgIoTransport::open(path)?;
+    let device = SgIoTransport::resolve_to_sg(path);
+    let c_path = SgIoTransport::to_c_path(&device);
+    let fd = unsafe {
+        libc::open(
+            c_path.as_ptr() as *const libc::c_char,
+            libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
+        )
+    };
+    if fd < 0 {
+        return SgIoTransport::open_error(&device);
+    }
+
     let cdb = [crate::scsi::SCSI_TEST_UNIT_READY, 0, 0, 0, 0, 0];
-    let mut buf = [0u8; 0];
-    match transport.execute(
-        &cdb,
-        crate::scsi::DataDirection::None,
-        &mut buf,
-        crate::scsi::TUR_TIMEOUT_MS,
-    ) {
-        Ok(_) => Ok(true),
+    let mut sense = [0u8; 32];
+    let mut hdr: sg_io_hdr = unsafe { std::mem::zeroed() };
+    hdr.interface_id = b'S' as i32;
+    hdr.dxfer_direction = SG_DXFER_NONE;
+    hdr.cmd_len = cdb.len() as u8;
+    hdr.mx_sb_len = sense.len() as u8;
+    hdr.dxfer_len = 0;
+    hdr.dxferp = std::ptr::null_mut();
+    hdr.cmdp = cdb.as_ptr();
+    hdr.sbp = sense.as_mut_ptr();
+    hdr.timeout = crate::scsi::TUR_TIMEOUT_MS;
+    hdr.flags = SG_FLAG_Q_AT_HEAD;
+
+    let ret = unsafe { libc::ioctl(fd, SG_IO as _, &mut hdr as *mut sg_io_hdr) };
+    unsafe { libc::close(fd) };
+
+    if ret < 0 {
+        return Err(Error::IoError {
+            source: std::io::Error::last_os_error(),
+        });
+    }
+
+    let driver_status_real = hdr.driver_status & !super::DRIVER_SENSE;
+    if hdr.host_status != 0 || driver_status_real != 0 {
+        return Err(Error::ScsiError {
+            opcode: cdb[0],
+            status: super::SCSI_STATUS_TRANSPORT_FAILURE,
+            sense: None,
+        });
+    }
+
+    if hdr.status == 0 {
+        return Ok(true);
+    }
+
+    let parsed = super::parse_sense(&sense, hdr.sb_len_wr);
+    if parsed.is_not_ready() {
+        Ok(false)
+    } else {
         Err(Error::ScsiError {
-            sense_key: SENSE_KEY_NOT_READY,
-            ..
-        }) => Ok(false),
-        Err(e) => Err(e),
+            opcode: cdb[0],
+            status: hdr.status,
+            sense: Some(parsed),
+        })
     }
 }

src/scsi/macos.rs

@@ -1,186 +1,55 @@
-//! macOS SCSI transport via IOKit SCSITaskDeviceInterface.
+//! macOS SCSI transport: IOKit SCSITaskDeviceInterface with exclusive access.
 //!
-//! Sends SCSI commands to optical drives through IOKit's SCSI Architecture
-//! Model family. Accepts BSD device paths like `/dev/disk2` or `/dev/rdisk2`.
+//! Single dispatch path: **all** CDBs (INQUIRY, READ, REPORT KEY, etc.) go
+//! through `SCSITaskDeviceInterface::ExecuteTaskSync` — 1:1 with the Linux
+//! SG_IO backend. The C shim (`macos_shim.c`) handles:
 //!
-//! Requires exclusive access to the device — unmount the disc first:
-//! `diskutil unmountDisk /dev/disk2`
+//! 1. `diskutil unmountDisk force` on the target device only
+//! 2. Find `IOBDServices` matching the requested BSD name (walks IOKit
+//!    registry: IOBDServices → IOBDBlockStorageDriver → IOMedia → BSD Name)
+//! 3. Create `MMCDeviceInterface` → `SCSITaskDeviceInterface`
+//! 4. `ObtainExclusiveAccess`
+//! 5. Raw CDB dispatch via `CreateSCSITask` + `ExecuteTaskSync`
+//!
+//! Drive enumeration (`list_drives`) uses the IOKit registry directly via
+//! `shim_list_drives` — no exclusive access, no SCSI commands, no unmounts.
 
 use super::{DataDirection, ScsiResult, ScsiTransport};
 use crate::error::{Error, Result};
 use std::path::Path;
 
-// ── IOKit / CoreFoundation type aliases ─────────────────────────────────────
-
-type CFMutableDictionaryRef = *mut std::ffi::c_void;
-type IOObject = u32;
-type IOReturn = i32;
-type MachPort = u32;
-
-/// Opaque COM interface pointer — `*mut *mut VTable` (double-indirect).
-/// IOKit plugins use COM-style vtables: the pointer points to a pointer
-/// to the function table.
-type ComRef = *mut *mut std::ffi::c_void;
-
-const K_IO_RETURN_SUCCESS: IOReturn = 0;
-
-// SCSI data transfer directions (SCSITaskLib.h)
-const K_SCSI_DATA_TRANSFER_NO_DATA: u8 = 0;
-const K_SCSI_DATA_TRANSFER_FROM_TARGET: u8 = 1;
-const K_SCSI_DATA_TRANSFER_TO_TARGET: u8 = 2;
-
-// SCSI task status values
-const K_SCSI_TASK_STATUS_GOOD: u8 = 0x00;
-
-const K_MAX_CDB_SIZE: usize = 16;
 const K_SENSE_DATA_SIZE: usize = 32;
 
-// ── IOKit plugin UUIDs ──────────────────────────────────────────────────────
-// From IOKit/scsi/SCSITaskLib.h
-
-/// kIOMMCDeviceUserClientTypeID — plugin type for MMC (optical) devices.
-const K_IO_MMC_DEVICE_USER_CLIENT_TYPE_ID: [u8; 16] = [
-    0x97, 0xAB, 0xCF, 0x5C, 0x45, 0x71, 0x11, 0xD6, 0xB6, 0xA0, 0x00, 0x30, 0x65, 0xA4, 0x7A, 0xEE,
-];
-
-/// kIOCFPlugInInterfaceID — base IOCFPlugin interface.
-const K_IO_CFPLUGIN_INTERFACE_ID: [u8; 16] = [
-    0xC2, 0x44, 0xE8, 0x58, 0x10, 0x9C, 0x11, 0xD4, 0x91, 0xD4, 0x00, 0x50, 0xE4, 0xC6, 0x42, 0x6F,
-];
-
-/// kIOSCSITaskDeviceInterfaceID — the interface we QueryInterface for.
-const K_IO_SCSI_TASK_DEVICE_INTERFACE_ID: [u8; 16] = [
-    0x61, 0x3E, 0x48, 0xB0, 0x30, 0x01, 0x11, 0xD6, 0xA4, 0xC0, 0x00, 0x0A, 0x27, 0x05, 0x28, 0x61,
-];
-
-// ── Scatter/gather element ──────────────────────────────────────────────────
-
 #[repr(C)]
-struct SCSITaskSGElement {
-    address: u64,
-    length: u64,
+#[derive(Copy, Clone)]
+struct ShimDriveInfo {
+    bsd_name: [u8; 32],
+    vendor: [u8; 32],
+    model: [u8; 48],
+    firmware: [u8; 16],
 }
 
-// ── External IOKit / CoreFoundation functions ───────────────────────────────
-
-// Rust 2024: FFI blocks declaring extern fns must be `unsafe extern`.
 unsafe extern "C" {
-    fn IOMasterPort(bootstrap: u32, master: *mut MachPort) -> IOReturn;
-    fn IOBSDNameMatching(
-        master: MachPort,
-        options: u32,
-        bsd_name: *const u8,
-    ) -> CFMutableDictionaryRef;
-    fn IOServiceGetMatchingService(master: MachPort, matching: CFMutableDictionaryRef) -> IOObject;
-    fn IOObjectRelease(object: IOObject) -> IOReturn;
-    fn IORegistryEntryGetParentEntry(
-        entry: IOObject,
-        plane: *const u8,
-        parent: *mut IOObject,
-    ) -> IOReturn;
-    fn IOObjectConformsTo(object: IOObject, class_name: *const u8) -> u8;
-    fn IOCreatePlugInInterfaceForService(
-        service: IOObject,
-        plugin_type: *const [u8; 16],
-        interface_type: *const [u8; 16],
-        the_interface: *mut ComRef,
-        the_score: *mut i32,
-    ) -> IOReturn;
+    fn shim_open_exclusive(bsd_name: *const u8) -> i32;
+    fn shim_close();
+    fn shim_execute(
+        cdb: *const u8,
+        cdb_len: u8,
+        buf: *mut u8,
+        buf_len: u32,
+        data_in: i32,
+        sense_out: *mut u8,
+        sense_len: u32,
+        task_status_out: *mut u8,
+        transfer_count: *mut u64,
+    ) -> i32;
+    fn shim_list_drives(out: *mut ShimDriveInfo, max_entries: i32) -> i32;
 }
 
-// ── COM vtable helpers ──────────────────────────────────────────────────────
-//
-// IOKit plugin interfaces use COM-style vtables. A ComRef is **vtable —
-// dereferencing once gives the vtable pointer, then index into it for
-// individual function pointers.
-//
-// All vtable indices verified against Apple open source:
-// IOSCSIArchitectureModelFamily/UserClientLib/SCSITaskLib.h
-
-/// Read a function pointer from a COM vtable at the given index.
-///
-/// # Safety
-/// `iface` must be a valid COM interface pointer (*mut *mut c_void), and
-/// `index` must be a valid vtable slot for the target type `T`.
-unsafe fn vtable_fn<T>(iface: ComRef, index: usize) -> T {
-    // Rust 2024: `unsafe fn` bodies are no longer implicitly unsafe.
-    // Each unsafe op needs its own `unsafe { }` block.
-    unsafe {
-        let vtable = *iface as *const *const std::ffi::c_void;
-        let fn_ptr = *vtable.add(index);
-        std::mem::transmute_copy(&fn_ptr)
-    }
-}
-
-/// Call Release (vtable index 3) on any COM interface.
-fn com_release(iface: ComRef) {
-    type Fn = unsafe extern "C" fn(ComRef) -> u32;
-    unsafe {
-        let f: Fn = vtable_fn(iface, 3);
-        f(iface);
-    }
-}
-
-// ── SCSITaskDeviceInterface vtable ──────────────────────────────────────────
-//
-// Index  Method
-//   0    _reserved
-//   1    QueryInterface
-//   2    AddRef
-//   3    Release
-//   4    IsExclusiveAccessAvailable
-//   5    AddCallbackDispatcherToRunLoop
-//   6    RemoveCallbackDispatcherFromRunLoop
-//   7    ObtainExclusiveAccess
-//   8    ReleaseExclusiveAccess
-//   9    CreateSCSITask
-
-const VTIDX_OBTAIN_EXCLUSIVE: usize = 7;
-const VTIDX_RELEASE_EXCLUSIVE: usize = 8;
-const VTIDX_CREATE_TASK: usize = 9;
-
-// ── SCSITaskInterface vtable ────────────────────────────────────────────────
-//
-// Index  Method
-//   0    _reserved
-//   1    QueryInterface
-//   2    AddRef
-//   3    Release
-//   4    IsTaskActive
-//   5    SetTaskAttribute
-//   6    GetTaskAttribute
-//   7    GetTaskState
-//   8    SetCommandDescriptorBlock
-//   9    GetCommandDescriptorBlockSize
-//  10    GetCommandDescriptorBlock
-//  11    SetScatterGatherEntries
-//  12    SetTimeoutDuration
-//  13    GetTimeoutDuration
-//  14    SetTaskCompletionCallback
-//  15    ExecuteTaskSync
-//  16    ExecuteTaskAsync
-//  17    AbortTask
-//  18    GetSCSIServiceResponse
-//  19    GetTaskStatus
-//  20    GetRealizedDataTransferCount
-//  21    GetAutoSenseData
-
-const VTIDX_SET_CDB: usize = 8;
-const VTIDX_SET_SG: usize = 11;
-const VTIDX_SET_TIMEOUT: usize = 12;
-const VTIDX_EXECUTE_SYNC: usize = 15;
-
-// ── Transport implementation ────────────────────────────────────────────────
-
 pub struct MacScsiTransport {
-    device_iface: ComRef,
-    exclusive: bool,
-    /// BSD name (e.g. "disk2") retained for `try_recover()` after a
-    /// task-level failure. Without it we can't re-call `find_scsi_service`.
-    bsd_name: String,
+    _bsd_name: String,
 }
 
-// IOKit COM interface pointers are Mach port references — safe to send between threads.
 unsafe impl Send for MacScsiTransport {}
 
 impl MacScsiTransport {
@@ -189,7 +58,6 @@ impl MacScsiTransport {
             path: device.display().to_string(),
         })?;
 
-        // Strip /dev/ prefix to get BSD name (e.g. "disk2")
         let bsd_name = if let Some(rest) = dev_str.strip_prefix("/dev/r") {
             rest
         } else if let Some(rest) = dev_str.strip_prefix("/dev/") {
@@ -198,170 +66,119 @@ impl MacScsiTransport {
             dev_str
         };
 
-        let device_iface = Self::acquire_device_iface(bsd_name)?;
+        let mut bsd_c = bsd_name.as_bytes().to_vec();
+        bsd_c.push(0);
+
+        let rc = unsafe { shim_open_exclusive(bsd_c.as_ptr()) };
+        if rc != 0 {
+            return Err(Error::DeviceNotFound {
+                path: bsd_name.to_string(),
+            });
+        }
 
         Ok(MacScsiTransport {
-            device_iface,
-            exclusive: true,
-            bsd_name: bsd_name.to_string(),
+            _bsd_name: bsd_name.to_string(),
         })
     }
-
-    /// Resolve the BSD name → IOKit SCSITaskDeviceInterface with exclusive
-    /// access. Shared between `open()` and `try_recover()`. Returns the
-    /// COM ref the caller must release.
-    fn acquire_device_iface(bsd_name: &str) -> Result<ComRef> {
-        let service = find_scsi_service(bsd_name)?;
-
-        // Create IOKit plugin for the MMC device
-        let mut plugin: ComRef = std::ptr::null_mut();
-        let mut score: i32 = 0;
-        let kr = unsafe {
-            IOCreatePlugInInterfaceForService(
-                service,
-                &K_IO_MMC_DEVICE_USER_CLIENT_TYPE_ID,
-                &K_IO_CFPLUGIN_INTERFACE_ID,
-                &mut plugin,
-                &mut score,
-            )
-        };
-        unsafe { IOObjectRelease(service) };
-
-        if kr != K_IO_RETURN_SUCCESS || plugin.is_null() {
-            return Err(Error::IoKitPluginFailed {
-                path: bsd_name.to_string(),
-                kr: kr as u32,
-            });
-        }
-
-        // QueryInterface for SCSITaskDeviceInterface
-        let mut device_iface: ComRef = std::ptr::null_mut();
-        let hr = unsafe {
-            type QiFn = unsafe extern "C" fn(ComRef, *const [u8; 16], *mut ComRef) -> i32;
-            let qi: QiFn = vtable_fn(plugin, 1);
-            qi(
-                plugin,
-                &K_IO_SCSI_TASK_DEVICE_INTERFACE_ID,
-                &mut device_iface,
-            )
-        };
-        com_release(plugin);
-
-        if hr != 0 || device_iface.is_null() {
-            return Err(Error::ScsiInterfaceUnavailable {
-                path: bsd_name.to_string(),
-            });
-        }
-
-        // Obtain exclusive access
-        let kr = unsafe {
-            type Fn = unsafe extern "C" fn(ComRef) -> IOReturn;
-            let f: Fn = vtable_fn(device_iface, VTIDX_OBTAIN_EXCLUSIVE);
-            f(device_iface)
-        };
-        if kr != K_IO_RETURN_SUCCESS {
-            com_release(device_iface);
-            return Err(Error::DeviceLocked {
-                path: bsd_name.to_string(),
-                kr: kr as u32,
-            });
-        }
-
-        Ok(device_iface)
-    }
-
-    /// Recover the IOKit interface after a task-level failure. Releases
-    /// the current device_iface and re-acquires fresh state via
-    /// `acquire_device_iface`. Same observable contract as the Linux fd
-    /// recovery: after `try_recover()`, the next `execute()` either uses a
-    /// fresh interface or returns `DeviceNotFound` if recovery failed.
-    ///
-    /// Synchronous because IOKit `RELEASE_EXCLUSIVE` + `com_release` don't
-    /// block on in-flight CDBs the way Linux SG_IO `close` does.
-    fn try_recover(&mut self) {
-        if !self.device_iface.is_null() {
-            if self.exclusive {
-                unsafe {
-                    type Fn = unsafe extern "C" fn(ComRef) -> IOReturn;
-                    let f: Fn = vtable_fn(self.device_iface, VTIDX_RELEASE_EXCLUSIVE);
-                    f(self.device_iface);
-                }
-                self.exclusive = false;
-            }
-            com_release(self.device_iface);
-            self.device_iface = std::ptr::null_mut();
-        }
-        match Self::acquire_device_iface(&self.bsd_name) {
-            Ok(new_iface) => {
-                self.device_iface = new_iface;
-                self.exclusive = true;
-            }
-            Err(_) => {
-                // Leave device_iface null; next execute() returns
-                // DeviceNotFound. Caller's retry path will reopen Drive.
-                self.device_iface = std::ptr::null_mut();
-                self.exclusive = false;
-            }
-        }
-    }
-
-    // `reset()` removed in 0.13.6 — see scsi/mod.rs for rationale.
 }
 
-/// Enumerate optical drives on macOS. Mirrors `drive::macos::find_drives`
-/// (which iterates `/dev/disk0..15` + INQUIRY + filters peripheral
-/// type 5). Same logic, exposed through the new `DriveInfo` shape so
-/// callers — `list_drives()` in `scsi::mod` — never reach into
-/// `crate::drive::macos`.
-pub(super) fn list_drives() -> Vec<super::DriveInfo> {
-    let mut out = Vec::new();
-    for i in 0..K_DEV_DISK_MAX {
-        let path = format!("/dev/disk{i}");
-        if !std::path::Path::new(&path).exists() {
-            continue;
+impl Drop for MacScsiTransport {
+    fn drop(&mut self) {
+        unsafe { shim_close() };
+    }
+}
+
+impl ScsiTransport for MacScsiTransport {
+    fn execute(
+        &mut self,
+        cdb: &[u8],
+        direction: DataDirection,
+        data: &mut [u8],
+        _timeout_ms: u32,
+    ) -> Result<ScsiResult> {
+        let data_in = match direction {
+            DataDirection::FromDevice => 1,
+            DataDirection::ToDevice => 0,
+            DataDirection::None => 0,
+        };
+
+        let mut sense = [0u8; K_SENSE_DATA_SIZE];
+        let mut task_status: u8 = 0xFF;
+        let mut transfer_count: u64 = 0;
+
+        let kr = unsafe {
+            shim_execute(
+                cdb.as_ptr(),
+                cdb.len() as u8,
+                data.as_mut_ptr(),
+                data.len() as u32,
+                data_in,
+                sense.as_mut_ptr(),
+                K_SENSE_DATA_SIZE as u32,
+                &mut task_status,
+                &mut transfer_count,
+            )
+        };
+
+        if kr != 0 {
+            return Err(Error::ScsiError {
+                opcode: cdb[0],
+                status: super::SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
+            });
         }
-        let mut transport = match MacScsiTransport::open(std::path::Path::new(&path)) {
-            Ok(t) => t,
-            Err(_) => continue,
-        };
-        let inquiry = match super::inquiry(&mut transport) {
-            Ok(r) => r,
-            Err(_) => continue,
-        };
-        // SCSI peripheral type field is the lower 5 bits of byte 0.
-        if inquiry.raw.is_empty()
-            || (inquiry.raw[K_INQUIRY_TYPE_BYTE] & K_INQUIRY_TYPE_MASK) != K_SCSI_TYPE_OPTICAL
-        {
+
+        if task_status != 0 {
+            let parsed = super::parse_sense(&sense, K_SENSE_DATA_SIZE as u8);
+            return Err(Error::ScsiError {
+                opcode: cdb[0],
+                status: task_status,
+                sense: Some(parsed),
+            });
+        }
+
+        Ok(ScsiResult {
+            status: 0,
+            bytes_transferred: transfer_count as usize,
+            sense,
+        })
+    }
+}
+
+// ── Drive enumeration (registry-based, no exclusive access) ──────────────
+
+pub(super) fn list_drives() -> Vec<super::DriveInfo> {
+    let mut buf = [ShimDriveInfo {
+        bsd_name: [0; 32],
+        vendor: [0; 32],
+        model: [0; 48],
+        firmware: [0; 16],
+    }; 8];
+
+    let count = unsafe { shim_list_drives(buf.as_mut_ptr(), buf.len() as i32) };
+
+    let mut out = Vec::new();
+    for i in 0..(count as usize).min(buf.len()) {
+        let info = &buf[i];
+        let bsd_name = cstr_to_str(&info.bsd_name);
+        if bsd_name.is_empty() {
             continue;
         }
         out.push(super::DriveInfo {
-            path,
-            vendor: inquiry.vendor_id,
-            model: inquiry.model,
-            firmware: inquiry.firmware,
+            path: format!("/dev/{bsd_name}"),
+            vendor: cstr_to_str(&info.vendor).to_string(),
+            model: cstr_to_str(&info.model).to_string(),
+            firmware: cstr_to_str(&info.firmware).to_string(),
         });
     }
     out
 }
 
-/// Maximum BSD disk index probed during enumeration. macOS assigns
-/// `/dev/diskN` sequentially per attached storage device; 16 covers
-/// any realistic homelab.
-const K_DEV_DISK_MAX: u8 = 16;
+fn cstr_to_str(bytes: &[u8]) -> &str {
+    let end = bytes.iter().position(|&b| b == 0).unwrap_or(bytes.len());
+    std::str::from_utf8(&bytes[..end]).unwrap_or("")
+}
 
-/// SCSI INQUIRY response: peripheral device type lives in byte 0,
-/// lower 5 bits.
-const K_INQUIRY_TYPE_BYTE: usize = 0;
-const K_INQUIRY_TYPE_MASK: u8 = 0x1F;
-
-/// SCSI peripheral type 5 = "CD-ROM device" (covers DVD, BD-ROM, BD-RE).
-const K_SCSI_TYPE_OPTICAL: u8 = 0x05;
-
-/// TEST UNIT READY probe on macOS. Any non-"not ready" error bubbles up
-/// to the caller — in-library wedge recovery was rolled back in 0.13.4
-/// after USB-layer resets failed to recover the LG BU40N on Linux; the
-/// macOS impl mirrors that choice for symmetry. See the Linux
-/// `drive_has_disc` in `scsi/linux.rs` for the full rationale.
 pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
     let mut transport = MacScsiTransport::open(path)?;
     let cdb = [crate::scsi::SCSI_TEST_UNIT_READY, 0, 0, 0, 0, 0];
@@ -373,244 +190,7 @@ pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
         crate::scsi::TUR_TIMEOUT_MS,
     ) {
         Ok(_) => Ok(true),
-        Err(Error::ScsiError { sense_key, .. }) if sense_key == K_SENSE_KEY_NOT_READY => Ok(false),
+        Err(ref e) if e.scsi_sense().is_some_and(|s| s.is_not_ready()) => Ok(false),
         Err(e) => Err(e),
     }
 }
-
-const K_SENSE_KEY_NOT_READY: u8 = 2;
-
-impl Drop for MacScsiTransport {
-    fn drop(&mut self) {
-        if self.device_iface.is_null() {
-            return;
-        }
-        if self.exclusive {
-            unsafe {
-                type Fn = unsafe extern "C" fn(ComRef) -> IOReturn;
-                let f: Fn = vtable_fn(self.device_iface, VTIDX_RELEASE_EXCLUSIVE);
-                f(self.device_iface);
-            }
-        }
-        com_release(self.device_iface);
-    }
-}
-
-impl ScsiTransport for MacScsiTransport {
-    fn execute(
-        &mut self,
-        cdb: &[u8],
-        direction: DataDirection,
-        data: &mut [u8],
-        timeout_ms: u32,
-    ) -> Result<ScsiResult> {
-        // Per RIP_DESIGN.md §15.1: parity with Linux/Windows recovery
-        // contract. If a prior execute() invalidated the interface and
-        // try_recover() also failed, fail fast.
-        if self.device_iface.is_null() {
-            return Err(Error::DeviceNotFound {
-                path: self.bsd_name.clone(),
-            });
-        }
-
-        // Create a SCSI task
-        let task: ComRef = unsafe {
-            type Fn = unsafe extern "C" fn(ComRef) -> ComRef;
-            let f: Fn = vtable_fn(self.device_iface, VTIDX_CREATE_TASK);
-            f(self.device_iface)
-        };
-        if task.is_null() {
-            self.try_recover();
-            return Err(Error::ScsiError {
-                opcode: cdb[0],
-                status: 0xFF,
-                sense_key: 0,
-            });
-        }
-
-        // Set CDB
-        let mut cdb_padded = [0u8; K_MAX_CDB_SIZE];
-        let cdb_len = cdb.len().min(K_MAX_CDB_SIZE);
-        cdb_padded[..cdb_len].copy_from_slice(&cdb[..cdb_len]);
-        unsafe {
-            type Fn = unsafe extern "C" fn(ComRef, *const u8, u8) -> IOReturn;
-            let f: Fn = vtable_fn(task, VTIDX_SET_CDB);
-            f(task, cdb_padded.as_ptr(), cdb_len as u8);
-        }
-
-        // Set scatter/gather and transfer direction
-        let iokit_dir = match direction {
-            DataDirection::None => K_SCSI_DATA_TRANSFER_NO_DATA,
-            DataDirection::FromDevice => K_SCSI_DATA_TRANSFER_FROM_TARGET,
-            DataDirection::ToDevice => K_SCSI_DATA_TRANSFER_TO_TARGET,
-        };
-
-        if direction != DataDirection::None && !data.is_empty() {
-            let sg = SCSITaskSGElement {
-                address: data.as_mut_ptr() as u64,
-                length: data.len() as u64,
-            };
-            unsafe {
-                type Fn =
-                    unsafe extern "C" fn(ComRef, *const SCSITaskSGElement, u8, u64, u8) -> IOReturn;
-                let f: Fn = vtable_fn(task, VTIDX_SET_SG);
-                f(task, &sg, 1, data.len() as u64, iokit_dir);
-            }
-        } else {
-            unsafe {
-                type Fn =
-                    unsafe extern "C" fn(ComRef, *const SCSITaskSGElement, u8, u64, u8) -> IOReturn;
-                let f: Fn = vtable_fn(task, VTIDX_SET_SG);
-                f(task, std::ptr::null(), 0, 0, K_SCSI_DATA_TRANSFER_NO_DATA);
-            }
-        }
-
-        // Set timeout (IOKit SCSITask takes milliseconds)
-        unsafe {
-            type Fn = unsafe extern "C" fn(ComRef, u32);
-            let f: Fn = vtable_fn(task, VTIDX_SET_TIMEOUT);
-            f(task, timeout_ms);
-        }
-
-        // Execute synchronously
-        let mut sense = [0u8; K_SENSE_DATA_SIZE];
-        let mut task_status: u32 = 0;
-        let mut realized_count: u64 = 0;
-
-        let kr = unsafe {
-            type Fn = unsafe extern "C" fn(ComRef, *mut u8, *mut u32, *mut u64) -> IOReturn;
-            let f: Fn = vtable_fn(task, VTIDX_EXECUTE_SYNC);
-            f(
-                task,
-                sense.as_mut_ptr(),
-                &mut task_status,
-                &mut realized_count,
-            )
-        };
-
-        com_release(task);
-
-        if kr != K_IO_RETURN_SUCCESS {
-            // Task-level failure (timeout / IOKit error). Recover the
-            // interface so the caller's retry path can resume.
-            self.try_recover();
-            return Err(Error::ScsiError {
-                opcode: cdb[0],
-                status: 0xFF,
-                sense_key: 0,
-            });
-        }
-
-        if task_status != K_SCSI_TASK_STATUS_GOOD as u32 {
-            let sense_key = if sense[2] != 0 { sense[2] & 0x0F } else { 0 };
-            return Err(Error::ScsiError {
-                opcode: cdb[0],
-                status: task_status as u8,
-                sense_key,
-            });
-        }
-
-        Ok(ScsiResult {
-            status: task_status as u8,
-            bytes_transferred: realized_count as usize,
-            sense,
-        })
-    }
-}
-
-// ── IOKit service discovery ─────────────────────────────────────────────────
-
-/// BSD name → IOKit service for the SCSI device.
-///
-/// Walk: IOMedia (BSD name match) → parent chain → SCSIPeripheralDeviceNub.
-///
-/// All failure paths surface as `Error::DeviceNotFound { path: bsd_name }` —
-/// the four internal stages (IOMasterPort / IOBSDNameMatching / IOMedia
-/// lookup / walk_to_authoring_device) collapse into one observable error
-/// because none of them are user-actionable individually. Pre-0.13 each
-/// stage stuffed an English description into `path:` ("…IOMasterPort
-/// failed", "…SCSITaskDeviceInterface not available", etc.) which broke
-/// the library's "no English text" rule.
-fn find_scsi_service(bsd_name: &str) -> Result<IOObject> {
-    let not_found = || Error::DeviceNotFound {
-        path: bsd_name.to_string(),
-    };
-
-    let mut master: MachPort = 0;
-    let kr = unsafe { IOMasterPort(0, &mut master) };
-    if kr != K_IO_RETURN_SUCCESS {
-        return Err(not_found());
-    }
-
-    // IOBSDNameMatching creates a dictionary matching { "BSD Name" = bsd_name }
-    let mut bsd_c = bsd_name.as_bytes().to_vec();
-    bsd_c.push(0);
-    let matching = unsafe { IOBSDNameMatching(master, 0, bsd_c.as_ptr()) };
-    if matching.is_null() {
-        return Err(not_found());
-    }
-
-    // Find the single IOMedia service (consumes the matching dict)
-    let media = unsafe { IOServiceGetMatchingService(master, matching) };
-    if media == 0 {
-        return Err(not_found());
-    }
-
-    // Walk up the IOService plane to find the authoring device.
-    // The chain is typically:
-    //   IOMedia → IOPartitionScheme → IOMedia → IOBlockStorageDriver
-    //   → IOSCSIPeripheralDeviceNub (this is what we want)
-    //
-    // We walk up until we find a service that IOCreatePlugInInterfaceForService
-    // accepts with kIOMMCDeviceUserClientTypeID, or until we hit the root.
-    let service = walk_to_authoring_device(media);
-    unsafe { IOObjectRelease(media) };
-
-    service.ok_or_else(not_found)
-}
-
-/// Walk up the IOService plane from an IOMedia to the SCSI authoring device.
-fn walk_to_authoring_device(start: IOObject) -> Option<IOObject> {
-    let mut current = start;
-    // Retain start so we can release uniformly in the loop
-    // (IORegistryEntryGetParentEntry retains the parent for us)
-
-    // Target class names for authoring devices
-    let target_classes: &[&[u8]] = &[
-        b"IOSCSIPeripheralDeviceNub\0",
-        b"IOBDBlockStorageDevice\0",
-        b"IODVDBlockStorageDevice\0",
-        b"IOCDBlockStorageDevice\0",
-        b"IOBlockStorageDevice\0",
-    ];
-
-    // Walk up to 10 levels (more than enough)
-    for _ in 0..10 {
-        let mut parent: IOObject = 0;
-        let kr = unsafe {
-            IORegistryEntryGetParentEntry(current, c"IOService".as_ptr() as *const u8, &mut parent)
-        };
-
-        if current != start {
-            unsafe { IOObjectRelease(current) };
-        }
-
-        if kr != K_IO_RETURN_SUCCESS || parent == 0 {
-            return None;
-        }
-
-        // Check if this parent matches any of our target classes
-        for class in target_classes {
-            if unsafe { IOObjectConformsTo(parent, class.as_ptr()) } != 0 {
-                return Some(parent);
-            }
-        }
-
-        current = parent;
-    }
-
-    if current != start {
-        unsafe { IOObjectRelease(current) };
-    }
-    None
-}

src/scsi/macos_shim.c

@@ -0,0 +1,376 @@
+#include <IOKit/IOKitLib.h>
+#include <IOKit/IOCFPlugIn.h>
+#include <IOKit/scsi/SCSITaskLib.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+// ── Types ──────────────────────────────────────────────────────────────────
+
+typedef struct {
+    IOCFPlugInInterface      **plugin;
+    MMCDeviceInterface       **mmc;
+    SCSITaskDeviceInterface  **scsi;
+    int                        exclusive;
+} ShimHandle;
+
+typedef struct {
+    char bsd_name[32];
+    char vendor[32];
+    char model[48];
+    char firmware[16];
+} ShimDriveInfo;
+
+// ── Global handle (single-drive, same as before) ──────────────────────────
+
+static ShimHandle g_handle = {NULL, NULL, NULL, 0};
+
+// ── Registry helpers ──────────────────────────────────────────────────────
+
+static int cfstring_to_cstr(CFStringRef cf, char *buf, size_t buflen) {
+    if (!cf) return 0;
+    if (!CFStringGetCString(cf, buf, buflen, kCFStringEncodingUTF8)) return 0;
+    return 1;
+}
+
+static int registry_entry_bsd_name(io_registry_entry_t entry, char *buf, size_t buflen) {
+    CFStringRef cf = IORegistryEntryCreateCFProperty(entry, CFSTR("BSD Name"),
+        kCFAllocatorDefault, 0);
+    if (!cf) return 0;
+    int ok = cfstring_to_cstr(cf, buf, buflen);
+    CFRelease(cf);
+    return ok;
+}
+
+static io_registry_entry_t find_iomedia_child(io_registry_entry_t parent) {
+    io_iterator_t iter;
+    kern_return_t kr = IORegistryEntryGetChildIterator(parent, kIOServicePlane, &iter);
+    if (kr != KERN_SUCCESS) return 0;
+
+    io_registry_entry_t child;
+    while ((child = IOIteratorNext(iter)) != 0) {
+        char cls[128];
+        kr = IOObjectGetClass(child, cls);
+        if (kr == KERN_SUCCESS) {
+            if (strcmp(cls, "IOMedia") == 0) {
+                IOObjectRelease(iter);
+                return child;
+            }
+        }
+        IOObjectRelease(child);
+    }
+    IOObjectRelease(iter);
+    return 0;
+}
+
+static io_registry_entry_t find_child_of_class(io_registry_entry_t parent, const char *target_class) {
+    io_iterator_t iter;
+    kern_return_t kr = IORegistryEntryGetChildIterator(parent, kIOServicePlane, &iter);
+    if (kr != KERN_SUCCESS) return 0;
+
+    io_registry_entry_t child;
+    while ((child = IOIteratorNext(iter)) != 0) {
+        char cls[128];
+        kr = IOObjectGetClass(child, cls);
+        if (kr == KERN_SUCCESS && strcmp(cls, target_class) == 0) {
+            IOObjectRelease(iter);
+            return child;
+        }
+        IOObjectRelease(child);
+    }
+    IOObjectRelease(iter);
+    return 0;
+}
+
+static io_registry_entry_t find_parent_of_class(io_registry_entry_t entry, const char *target_class) {
+    io_registry_entry_t parent;
+    kern_return_t kr = IORegistryEntryGetParentEntry(entry, kIOServicePlane, &parent);
+    if (kr != KERN_SUCCESS) return 0;
+
+    char cls[128];
+    kr = IOObjectGetClass(parent, cls);
+    if (kr == KERN_SUCCESS && strcmp(cls, target_class) == 0) {
+        return parent;
+    }
+    IOObjectRelease(parent);
+    return 0;
+}
+
+// Given an IOBDServices, find the BSD name of its IOMedia child.
+// Chain: IOBDServices -> IOBDBlockStorageDriver -> IOMedia (has "BSD Name")
+static int bdsvc_to_bsd_name(io_registry_entry_t bdsvc, char *buf, size_t buflen) {
+    io_registry_entry_t driver = find_child_of_class(bdsvc, "IOBDBlockStorageDriver");
+    if (!driver) return 0;
+
+    io_registry_entry_t media = find_iomedia_child(driver);
+    IOObjectRelease(driver);
+    if (!media) return 0;
+
+    int ok = registry_entry_bsd_name(media, buf, buflen);
+    IOObjectRelease(media);
+    return ok;
+}
+
+// Given an IOBDServices, extract Device Characteristics strings.
+static void bdsvc_device_info(io_registry_entry_t bdsvc, ShimDriveInfo *info) {
+    CFDictionaryRef dc = IORegistryEntryCreateCFProperty(bdsvc,
+        CFSTR("Device Characteristics"), kCFAllocatorDefault, 0);
+    if (!dc) return;
+
+    CFStringRef val;
+
+    val = CFDictionaryGetValue(dc, CFSTR("Vendor Name"));
+    if (val) cfstring_to_cstr(val, info->vendor, sizeof(info->vendor));
+
+    val = CFDictionaryGetValue(dc, CFSTR("Product Name"));
+    if (val) cfstring_to_cstr(val, info->model, sizeof(info->model));
+
+    val = CFDictionaryGetValue(dc, CFSTR("Product Revision Level"));
+    if (val) cfstring_to_cstr(val, info->firmware, sizeof(info->firmware));
+
+    CFRelease(dc);
+}
+
+// Find the IOBDServices that owns the given BSD name.
+// Returns a retained io_service_t (caller must release), or 0.
+static io_service_t find_bdsvc_by_bsd_name(mach_port_t mp, const char *bsd_name) {
+    CFMutableDictionaryRef matching = IOServiceMatching("IOBDServices");
+    if (!matching) return 0;
+
+    io_iterator_t iter;
+    kern_return_t kr = IOServiceGetMatchingServices(mp, matching, &iter);
+    if (kr != KERN_SUCCESS) return 0;
+
+    io_service_t result = 0;
+    io_service_t svc;
+    while ((svc = IOIteratorNext(iter)) != 0) {
+        char name[64];
+        if (bdsvc_to_bsd_name(svc, name, sizeof(name))) {
+            if (strcmp(name, bsd_name) == 0) {
+                result = svc;
+                break;
+            }
+        }
+        IOObjectRelease(svc);
+    }
+
+    if (!result) {
+        IOIteratorReset(iter);
+        while ((svc = IOIteratorNext(iter)) != 0) {
+            IOObjectRelease(svc);
+        }
+    }
+
+    IOObjectRelease(iter);
+    return result;
+}
+
+// Find the IOBDServices that owns the given BSD name by walking from
+// IOMedia upward. Used as fallback when bdsvc_to_bsd_name fails
+// (e.g. disc under exclusive access, no IOMedia child).
+// Chain: IOMedia -> IOBDBlockStorageDriver -> IOBDServices
+static io_service_t find_bdsvc_from_iomedia(mach_port_t mp, const char *bsd_name) {
+    CFMutableDictionaryRef matching = IOServiceMatching("IOMedia");
+    if (!matching) return 0;
+
+    io_iterator_t iter;
+    kern_return_t kr = IOServiceGetMatchingServices(mp, matching, &iter);
+    if (kr != KERN_SUCCESS) return 0;
+
+    io_service_t result = 0;
+    io_service_t media;
+    while ((media = IOIteratorNext(iter)) != 0) {
+        char name[64];
+        if (registry_entry_bsd_name(media, name, sizeof(name))
+            && strcmp(name, bsd_name) == 0)
+        {
+            io_registry_entry_t driver = find_parent_of_class(media, "IOBDBlockStorageDriver");
+            if (driver) {
+                io_registry_entry_t bdsvc = find_parent_of_class(driver, "IOBDServices");
+                IOObjectRelease(driver);
+                if (bdsvc) {
+                    result = bdsvc;
+                    IOObjectRelease(media);
+                    break;
+                }
+            }
+        }
+        IOObjectRelease(media);
+    }
+
+    IOObjectRelease(iter);
+    return result;
+}
+
+// ── Public API ────────────────────────────────────────────────────────────
+
+int shim_open_exclusive(const char *bsd_name) {
+    kern_return_t kr;
+    HRESULT hr;
+    SInt32 score = 0;
+
+    if (g_handle.exclusive && g_handle.scsi) {
+        return 0;
+    }
+
+    char cmd[128];
+    snprintf(cmd, sizeof(cmd), "diskutil unmountDisk force %s 2>/dev/null", bsd_name);
+    system(cmd);
+    usleep(500000);
+
+    mach_port_t mp;
+    IOMainPort(0, &mp);
+
+    io_service_t svc = find_bdsvc_by_bsd_name(mp, bsd_name);
+    if (!svc) {
+        svc = find_bdsvc_from_iomedia(mp, bsd_name);
+    }
+    if (!svc) {
+        CFMutableDictionaryRef matching = IOServiceMatching("IOBDServices");
+        svc = IOServiceGetMatchingService(mp, matching);
+    }
+    if (!svc) return -1;
+
+    kr = IOCreatePlugInInterfaceForService(svc,
+        kIOMMCDeviceUserClientTypeID, kIOCFPlugInInterfaceID,
+        &g_handle.plugin, &score);
+    IOObjectRelease(svc);
+
+    if (kr != KERN_SUCCESS || !g_handle.plugin) return -2;
+
+    hr = (*g_handle.plugin)->QueryInterface(g_handle.plugin,
+        CFUUIDGetUUIDBytes(kIOMMCDeviceInterfaceID), (LPVOID *)&g_handle.mmc);
+    if (hr != S_OK || !g_handle.mmc) {
+        IODestroyPlugInInterface(g_handle.plugin);
+        g_handle.plugin = NULL;
+        return -3;
+    }
+
+    g_handle.scsi = (*g_handle.mmc)->GetSCSITaskDeviceInterface(g_handle.mmc);
+    if (!g_handle.scsi) {
+        (*g_handle.mmc)->Release(g_handle.mmc);
+        IODestroyPlugInInterface(g_handle.plugin);
+        g_handle.mmc = NULL;
+        g_handle.plugin = NULL;
+        return -4;
+    }
+
+    kr = (*g_handle.scsi)->ObtainExclusiveAccess(g_handle.scsi);
+    if (kr != kIOReturnSuccess) {
+        (*g_handle.scsi)->Release(g_handle.scsi);
+        (*g_handle.mmc)->Release(g_handle.mmc);
+        IODestroyPlugInInterface(g_handle.plugin);
+        g_handle.scsi = NULL;
+        g_handle.mmc = NULL;
+        g_handle.plugin = NULL;
+        return -5;
+    }
+
+    g_handle.exclusive = 1;
+    return 0;
+}
+
+void shim_close(void) {
+    if (g_handle.exclusive && g_handle.scsi) {
+        (*g_handle.scsi)->ReleaseExclusiveAccess(g_handle.scsi);
+    }
+    if (g_handle.scsi) {
+        (*g_handle.scsi)->Release(g_handle.scsi);
+        g_handle.scsi = NULL;
+    }
+    if (g_handle.mmc) {
+        (*g_handle.mmc)->Release(g_handle.mmc);
+        g_handle.mmc = NULL;
+    }
+    if (g_handle.plugin) {
+        IODestroyPlugInInterface(g_handle.plugin);
+        g_handle.plugin = NULL;
+    }
+    g_handle.exclusive = 0;
+}
+
+int shim_execute(const unsigned char *cdb, unsigned char cdb_len,
+                 void *buf, unsigned int buf_len, int data_in,
+                 unsigned char *sense_out, unsigned int sense_len,
+                 unsigned char *task_status_out, unsigned long long *transfer_count) {
+    if (!g_handle.scsi) return -1;
+
+    SCSITaskInterface **task = (*g_handle.scsi)->CreateSCSITask(g_handle.scsi);
+    if (!task) return -2;
+
+    SCSICommandDescriptorBlock cdb_buf;
+    memset(&cdb_buf, 0, sizeof(cdb_buf));
+    memcpy(&cdb_buf, cdb, cdb_len);
+
+    (*task)->SetCommandDescriptorBlock(task, cdb_buf, cdb_len);
+
+    if (buf_len > 0 && buf) {
+        SCSITaskSGElement sg;
+        sg.address = (UInt64)(uintptr_t)buf;
+        sg.length = buf_len;
+        (*task)->SetScatterGatherEntries(task, &sg, 1, buf_len,
+            data_in ? kSCSIDataTransfer_FromTargetToInitiator
+                    : kSCSIDataTransfer_FromInitiatorToTarget);
+    } else {
+        (*task)->SetScatterGatherEntries(task, NULL, 0, 0,
+            kSCSIDataTransfer_NoDataTransfer);
+    }
+
+    (*task)->SetTimeoutDuration(task, 30000);
+
+    SCSI_Sense_Data sense;
+    memset(&sense, 0, sizeof(sense));
+    SCSITaskStatus status = 0xFF;
+    UInt64 count = 0;
+
+    IOReturn kr = (*task)->ExecuteTaskSync(task, &sense, &status, &count);
+
+    if (sense_out && sense_len > 0) {
+        size_t copy = sense_len < sizeof(sense) ? sense_len : sizeof(sense);
+        memcpy(sense_out, &sense, copy);
+    }
+    if (task_status_out) *task_status_out = (unsigned char)status;
+    if (transfer_count) *transfer_count = count;
+
+    (*task)->Release(task);
+
+    return (int)kr;
+}
+
+// ── Registry-based drive enumeration ──────────────────────────────────────
+//
+// Walks IOBDServices entries in the IOKit registry. No exclusive access,
+// no SCSI commands, no unmounts. Returns up to max_entries drives.
+
+int shim_list_drives(ShimDriveInfo *out, int max_entries) {
+    mach_port_t mp;
+    IOReturn ret = IOMainPort(0, &mp);
+    if (ret != kIOReturnSuccess) return 0;
+
+    CFMutableDictionaryRef matching = IOServiceMatching("IOBDServices");
+    if (!matching) return 0;
+
+    io_iterator_t iter;
+    kern_return_t kr = IOServiceGetMatchingServices(mp, matching, &iter);
+    if (kr != KERN_SUCCESS) return 0;
+
+    int count = 0;
+    io_service_t svc;
+    while ((svc = IOIteratorNext(iter)) != 0 && count < max_entries) {
+        ShimDriveInfo *info = &out[count];
+        memset(info, 0, sizeof(*info));
+
+        bdsvc_device_info(svc, info);
+        bdsvc_to_bsd_name(svc, info->bsd_name, sizeof(info->bsd_name));
+
+        if (info->bsd_name[0]) {
+            count++;
+        }
+
+        IOObjectRelease(svc);
+    }
+
+    IOObjectRelease(iter);
+    return count;
+}

src/scsi/mod.rs

@@ -2,11 +2,11 @@
 //!
 //! Platform backends are in separate files:
 //!   - `linux.rs` — SG_IO ioctl
-//!   - `macos.rs` — IOKit SCSITaskDeviceInterface
+//!   - `macos.rs` — IOKit SCSITaskDeviceInterface (exclusive access)
 //!   - `windows.rs` — SPTI (SCSI Pass-Through Interface)
 
 #[cfg(target_os = "linux")]
-mod linux;
+pub mod linux;
 #[cfg(target_os = "macos")]
 mod macos;
 #[cfg(target_os = "windows")]
@@ -43,6 +43,238 @@ pub const AACS_KEY_CLASS: u8 = 0x02;
 /// a poll-loop tick.
 pub(crate) const TUR_TIMEOUT_MS: u32 = 5_000;
 
+/// Timeout for content READ commands (READ_10 / READ_12) on the fast
+/// path — the [`disc::Disc::copy`] sweep that bisects-on-failure.
+///
+/// 10 s is calibrated from live empirical data on an LG BU40N + Initio
+/// 1618L bridge ripping a UHD with marginal sectors:
+///
+///   - Sustained sequential reads:    3 – 7 ms
+///   - Cold-start seek + read:        up to ~1500 ms
+///   - Successful ECC recovery:       1.6 – 2.6 sec
+///   - Confirmed unreadable sector:   3.6 – 8.8 sec (kernel timeout)
+///
+/// 10 s catches every legitimate slow read with comfortable margin and
+/// short-circuits truly bad sectors at ~10 s rather than letting the
+/// kernel mid-layer escalate for 30 s+. See the SCSI architecture audit
+/// (2026-04-26) for primary-source references.
+///
+/// Pre-0.13.21 this was 1.5 s, which forced the kernel mid-layer to
+/// time out *normal* reads (cold-start often takes ~1.5 s) and run its
+/// full ABORT TASK / LUN RESET / BUS RESET escalation while userspace
+/// kept submitting fresh reads. The Initio bridge couldn't drain the
+/// resulting command queue and entered a wedge state that only physical
+/// replug recovered — proven by the v0.13.18 + v0.13.20 live tests.
+pub(crate) const READ_TIMEOUT_MS: u32 = 10_000;
+
+/// Timeout for content READ commands on the recovery path —
+/// [`disc::Disc::patch`]'s targeted retries on bad ranges. Doubles
+/// the fast-path budget so a sector that fails at 30 s gets one more
+/// honest attempt. Matches sg_dd's default per-command timeout
+/// (`DEF_TIMEOUT = 60000`).
+pub(crate) const READ_RECOVERY_TIMEOUT_MS: u32 = 60_000;
+
+// ── SCSI status bytes (SPC-4 §4.5.5) ────────────────────────────────────────
+
+/// Status byte 0x00 — `GOOD`. Command completed successfully.
+pub const SCSI_STATUS_GOOD: u8 = 0x00;
+/// Status byte 0x02 — `CHECK CONDITION`. Drive completed the command
+/// reply and attached sense data describing the failure.
+pub const SCSI_STATUS_CHECK_CONDITION: u8 = 0x02;
+/// libfreemkv-synthesised sentinel: the transport never delivered a
+/// SCSI status byte (kernel timeout, USB bridge wedge, IOKit service
+/// failure). Distinct from any drive-returned value. Carriers
+/// [`Error::ScsiError`] with `sense = None`.
+pub const SCSI_STATUS_TRANSPORT_FAILURE: u8 = 0xFF;
+
+// ── SPC-4 sense keys (§4.5.6 Table 28) ─────────────────────────────────────
+//
+// Broad failure category returned in a CHECK CONDITION reply's sense data.
+// Names match the SCSI spec; predicate methods on [`ScsiSense`] (e.g.
+// `is_medium_error`, `is_unit_attention`) read more fluently than raw
+// constant comparisons at call sites.
+
+pub const SENSE_KEY_NO_SENSE: u8 = 0x00;
+pub const SENSE_KEY_RECOVERED_ERROR: u8 = 0x01;
+pub const SENSE_KEY_NOT_READY: u8 = 0x02;
+pub const SENSE_KEY_MEDIUM_ERROR: u8 = 0x03;
+pub const SENSE_KEY_HARDWARE_ERROR: u8 = 0x04;
+pub const SENSE_KEY_ILLEGAL_REQUEST: u8 = 0x05;
+pub const SENSE_KEY_UNIT_ATTENTION: u8 = 0x06;
+pub const SENSE_KEY_DATA_PROTECT: u8 = 0x07;
+pub const SENSE_KEY_BLANK_CHECK: u8 = 0x08;
+pub const SENSE_KEY_ABORTED_COMMAND: u8 = 0x0B;
+
+// ── Sense parsing ───────────────────────────────────────────────────────────
+
+/// Decoded SPC-4 sense triple — the precise reason a SCSI command failed.
+///
+/// Returned by [`parse_sense`] and embedded inside [`Error::ScsiError`]
+/// (`sense: Option<ScsiSense>`). Predicate methods (`is_medium_error`,
+/// `is_unit_attention`, `is_marginal`, …) read more fluently at call
+/// sites than raw `sense_key` comparisons.
+///
+/// `Default::default()` and the [`ScsiSense::NONE`] constant both
+/// produce the all-zero "no sense info" triple. Per SPC-4 §4.5.3, an
+/// empty sense buffer is reported as NO SENSE (key 0); use the constant
+/// for explicit intent at construction sites.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct ScsiSense {
+    /// Sense key — broad failure category (SPC-4 §4.5.6 Table 28).
+    /// See the `SENSE_KEY_*` constants for named values.
+    pub sense_key: u8,
+    /// Additional Sense Code — narrows the cause within a sense key
+    /// (SPC-4 §4.5.6 Table 29). E.g. `0x11` = UNRECOVERED READ ERROR.
+    pub asc: u8,
+    /// Additional Sense Code Qualifier — finest-grain disambiguation.
+    /// E.g. `0x05` (with `asc=0x11`) = L-EC UNCORRECTABLE.
+    pub ascq: u8,
+}
+
+impl ScsiSense {
+    /// Sense reply with all-zero fields — explicit "no sense info"
+    /// constructor for sites where `Default::default()` would be opaque.
+    pub const NONE: ScsiSense = ScsiSense {
+        sense_key: 0,
+        asc: 0,
+        ascq: 0,
+    };
+
+    /// `true` when the sense key indicates a *marginal-read* failure —
+    /// the kind of error where the same read at smaller granularity
+    /// (or a brief retry) sometimes succeeds:
+    ///
+    ///   - `MEDIUM ERROR` (3) — canonical bad-sector signal
+    ///   - `ABORTED COMMAND` (B) — transient; retry usually works
+    ///   - `RECOVERED ERROR` (1) / `NO SENSE` (0) — drive is healthy and
+    ///     either recovered the data or has no specific fault to report
+    ///
+    /// `false` for HARDWARE ERROR, DATA PROTECT, UNIT ATTENTION, NOT
+    /// READY, ILLEGAL REQUEST, BLANK CHECK, and any unknown key. Used
+    /// by [`Error::is_marginal_read`] / `Disc::copy`'s hysteresis
+    /// dispatch.
+    pub fn is_marginal(&self) -> bool {
+        matches!(
+            self.sense_key,
+            SENSE_KEY_NO_SENSE
+                | SENSE_KEY_RECOVERED_ERROR
+                | SENSE_KEY_MEDIUM_ERROR
+                | SENSE_KEY_ABORTED_COMMAND
+        )
+    }
+
+    /// `true` if `sense_key == MEDIUM ERROR (3)` — canonical "bad sector"
+    /// signal from the drive.
+    pub fn is_medium_error(&self) -> bool {
+        self.sense_key == SENSE_KEY_MEDIUM_ERROR
+    }
+
+    /// `true` if `sense_key == HARDWARE ERROR (4)` — drive itself is
+    /// failing. Not recoverable by retry.
+    pub fn is_hardware_error(&self) -> bool {
+        self.sense_key == SENSE_KEY_HARDWARE_ERROR
+    }
+
+    /// `true` if `sense_key == NOT READY (2)` — medium not present /
+    /// drive becoming ready / etc.
+    pub fn is_not_ready(&self) -> bool {
+        self.sense_key == SENSE_KEY_NOT_READY
+    }
+
+    /// `true` if `sense_key == UNIT ATTENTION (6)` — disc/drive state
+    /// changed since the prior command (media inserted/removed,
+    /// power-on reset, parameters changed). Caller should rescan rather
+    /// than retry the read.
+    pub fn is_unit_attention(&self) -> bool {
+        self.sense_key == SENSE_KEY_UNIT_ATTENTION
+    }
+
+    /// `true` if `sense_key == DATA PROTECT (7)` — read blocked by
+    /// AACS / region / write-protect. Retry won't help.
+    pub fn is_data_protect(&self) -> bool {
+        self.sense_key == SENSE_KEY_DATA_PROTECT
+    }
+
+    /// `true` if `sense_key == ILLEGAL REQUEST (5)` — typically a bug
+    /// in the CDB we sent (LBA out of range, reserved bit, etc.). Don't
+    /// retry.
+    pub fn is_illegal_request(&self) -> bool {
+        self.sense_key == SENSE_KEY_ILLEGAL_REQUEST
+    }
+
+    /// `true` if `sense_key == ABORTED COMMAND (B)` — transient; one
+    /// retry is usually safe.
+    pub fn is_aborted_command(&self) -> bool {
+        self.sense_key == SENSE_KEY_ABORTED_COMMAND
+    }
+}
+
+/// Decode an SPC-4 sense buffer into the structured triple
+/// `(sense_key, asc, ascq)`.
+///
+/// Handles both response-code formats SPC-4 mandates:
+///
+///   - **Descriptor format** (response code `0x72` / `0x73`):
+///     - sense key = `sense[1] & 0x0F`
+///     - asc = `sense[2]`
+///     - ascq = `sense[3]`
+///   - **Fixed format** (response code `0x70` / `0x71` and any unknown
+///     code per SPC-4 §4.5.3):
+///     - sense key = `sense[2] & 0x0F`
+///     - asc = `sense[12]`
+///     - ascq = `sense[13]`
+///
+/// `sb_len_wr` is the number of bytes the transport actually wrote into
+/// `sense`. When the buffer is too short for the relevant fields we
+/// return [`ScsiSense::NONE`] for the missing pieces rather than reading
+/// uninitialised memory. The minimum useful sense reply per SPC-4 is 8
+/// bytes (descriptor) or 14 bytes (fixed, to reach ASC/ASCQ at offsets
+/// 12/13).
+///
+/// Pure function — same parse on every platform backend (Linux SG_IO,
+/// macOS IOKit, Windows SPTI) so a regression here would silently
+/// mis-route SCSI errors on all three OSes simultaneously.
+pub(crate) fn parse_sense(sense: &[u8], sb_len_wr: u8) -> ScsiSense {
+    let n = (sb_len_wr as usize).min(sense.len());
+    if n < 3 {
+        return ScsiSense::NONE;
+    }
+    let response_code = sense[0] & 0x7F;
+    let descriptor = response_code == 0x72 || response_code == 0x73;
+    if descriptor {
+        // Descriptor format: key/asc/ascq are at fixed offsets 1/2/3.
+        let asc = if n >= 3 { sense[2] } else { 0 };
+        let ascq = if n >= 4 { sense[3] } else { 0 };
+        ScsiSense {
+            sense_key: sense[1] & 0x0F,
+            asc,
+            ascq,
+        }
+    } else {
+        // Fixed format: key at byte 2, ASC/ASCQ at bytes 12/13.
+        let asc = if n >= 13 { sense[12] } else { 0 };
+        let ascq = if n >= 14 { sense[13] } else { 0 };
+        ScsiSense {
+            sense_key: sense[2] & 0x0F,
+            asc,
+            ascq,
+        }
+    }
+}
+
+// ── SG_IO driver_status bits ────────────────────────────────────────────────
+
+/// `DRIVER_SENSE` (0x08) — bit set in `driver_status` to indicate that
+/// sense data was attached to a CHECK CONDITION reply. **Not** a transport
+/// failure on its own. Mask this off before deciding whether `driver_status`
+/// represents a real bus/host problem.
+///
+/// Used by Linux SG_IO (`sg_io_hdr.driver_status`); macOS IOKit and
+/// Windows SPTI carry the equivalent signal in different fields and
+/// don't need the same masking — the misclassification was Linux-only.
+#[cfg(target_os = "linux")]
+pub(crate) const DRIVER_SENSE: u16 = 0x08;
+
 // ── Types ───────────────────────────────────────────────────────────────────
 
 #[derive(Debug, Clone, Copy, PartialEq)]
@@ -102,9 +334,9 @@ pub fn open(device: &Path) -> Result<Box<dyn ScsiTransport>> {
 // platform reset in a thread+recv_timeout so a kernel-wedged ioctl
 // couldn't hang the caller. Removed in 0.13.6 along with the
 // SG_SCSI_RESET / STOP+START UNIT escalation that needed it. The
-// remaining platform reset (Linux: SgIoTransport::reset, called only
-// from SgIoTransport::open) does pure userspace state cleanup with
-// bounded sleeps — no escape-hatch wrapper required.
+// remaining platform reset (Linux: SgIoTransport::reset, available
+// for explicit opt-in) does pure userspace state cleanup with bounded
+// sleeps — no escape-hatch wrapper required.
 
 // ── USB-layer recovery: rolled back in 0.13.4 ───────────────────────────────
 //
@@ -326,3 +558,116 @@ pub fn build_read10_raw(lba: u32, count: u16) -> [u8; 10] {
         0x00,
     ]
 }
+
+#[cfg(test)]
+mod parse_sense_tests {
+    //! Unit tests for `parse_sense_key`. Covers both SPC-4 sense data
+    //! formats (descriptor / fixed) and the short-buffer fallback. The
+    //! same helper runs on every platform backend so a regression here
+    //! would silently miscategorize SCSI errors on Linux, macOS, and
+    //! Windows simultaneously.
+    use super::parse_sense;
+    fn parse_sense_key(sense: &[u8], sb_len_wr: u8) -> u8 {
+        parse_sense(sense, sb_len_wr).sense_key
+    }
+
+    /// Helper: build a 32-byte sense buffer whose first three bytes are
+    /// the given prefix; the rest are zeroes (sense data area).
+    fn buf(b0: u8, b1: u8, b2: u8) -> [u8; 32] {
+        let mut s = [0u8; 32];
+        s[0] = b0;
+        s[1] = b1;
+        s[2] = b2;
+        s
+    }
+
+    #[test]
+    fn descriptor_format_72_picks_byte_1() {
+        // Response code 0x72 (current, descriptor): sense key is the
+        // low nibble of byte 1. Byte 2 here is 0x77 to prove it is NOT
+        // the byte the parser reads.
+        let s = buf(0x72, 0x05, 0x77); // ILLEGAL REQUEST
+        assert_eq!(parse_sense_key(&s, 8), 5);
+    }
+
+    #[test]
+    fn descriptor_format_73_picks_byte_1() {
+        // Response code 0x73 (deferred, descriptor): same parse rule
+        // as 0x72.
+        let s = buf(0x73, 0x06, 0xFF); // UNIT ATTENTION
+        assert_eq!(parse_sense_key(&s, 8), 6);
+    }
+
+    #[test]
+    fn fixed_format_70_picks_byte_2() {
+        // Response code 0x70 (current, fixed): sense key is the low
+        // nibble of byte 2. Byte 1 is 0x77 to prove it is NOT read.
+        let s = buf(0x70, 0x77, 0x05); // ILLEGAL REQUEST
+        assert_eq!(parse_sense_key(&s, 18), 5);
+    }
+
+    #[test]
+    fn fixed_format_71_picks_byte_2() {
+        // Response code 0x71 (deferred, fixed): same parse as 0x70.
+        let s = buf(0x71, 0x77, 0x02); // NOT READY
+        assert_eq!(parse_sense_key(&s, 18), 2);
+    }
+
+    #[test]
+    fn high_bit_in_byte_0_is_masked() {
+        // SPC-4 sets the top bit of byte 0 ("INFORMATION VALID" / "VALID")
+        // independently of the response code. parse_sense_key must mask
+        // it off before classifying the format.
+        let s = buf(0xF2, 0x05, 0x77);
+        assert_eq!(
+            parse_sense_key(&s, 8),
+            5,
+            "VALID-bit must not leak into format detection"
+        );
+        let s = buf(0xF0, 0x77, 0x02);
+        assert_eq!(parse_sense_key(&s, 18), 2);
+    }
+
+    #[test]
+    fn high_nibble_in_key_byte_is_masked() {
+        // Sense key is byte_n & 0x0F (low nibble). Top nibble holds
+        // FILEMARK / EOM / ILI / SDAT_OVFL flags, which must not bleed
+        // into the key value.
+        let s = buf(0x70, 0x00, 0xE5); // 0xE0 flags + key 5
+        assert_eq!(parse_sense_key(&s, 18), 5);
+    }
+
+    #[test]
+    fn sb_len_wr_zero_returns_no_sense() {
+        // Transport set status non-zero but wrote zero sense bytes —
+        // SPC-4 §4.5.3 says treat as NO SENSE (key 0).
+        let s = buf(0x72, 0x05, 0x05);
+        assert_eq!(parse_sense_key(&s, 0), 0);
+    }
+
+    #[test]
+    fn sb_len_wr_below_three_returns_no_sense() {
+        // Less than three bytes in the buffer means we can't safely
+        // read either format byte 0 or key byte 2 — return 0.
+        let s = buf(0x72, 0x05, 0x05);
+        assert_eq!(parse_sense_key(&s, 1), 0);
+        assert_eq!(parse_sense_key(&s, 2), 0);
+    }
+
+    #[test]
+    fn slice_below_three_returns_no_sense() {
+        // Defense-in-depth: even if a caller passes a too-short slice
+        // with a falsely-large sb_len_wr, we don't panic and we return 0.
+        let s = [0x72u8, 0x05];
+        assert_eq!(parse_sense_key(&s, 8), 0);
+    }
+
+    #[test]
+    fn unknown_response_code_falls_through_to_fixed() {
+        // SPC-4 mandates implementations tolerate unknown response
+        // codes and treat them as fixed format. Vendor-specific codes
+        // in the 0x74..0x7E range surface here.
+        let s = buf(0x7A, 0x77, 0x03); // MEDIUM ERROR via "fixed"
+        assert_eq!(parse_sense_key(&s, 18), 3);
+    }
+}

src/scsi/windows.rs

@@ -85,15 +85,11 @@ unsafe extern "system" {
 
 pub struct SptiTransport {
     handle: isize,
-    /// Wide-encoded device path used by `try_recover()` to reopen the
-    /// handle after a failed DeviceIoControl. Saved from `open()` so we
-    /// don't have to re-resolve the device path on recovery.
-    wide_path: Vec<u16>,
 }
 
-// SptiTransport contains an isize HANDLE and a Vec<u16>; both Send. The
-// auto-derived Send is intentional. Sync is NOT — handle mutation in
-// execute() requires &mut, enforced by the trait object dispatch.
+// SptiTransport's only field is the isize HANDLE — Send is auto-derived
+// and intentional. Sync is NOT: handle mutation in execute() requires
+// &mut, enforced by the trait object dispatch.
 
 /// Normalize a device path to Windows \\.\X: format.
 ///
@@ -151,34 +147,7 @@ impl SptiTransport {
             });
         }
 
-        Ok(SptiTransport {
-            handle,
-            wide_path: wide,
-        })
-    }
-
-    /// Recover the handle after a failed DeviceIoControl. Closes the bad
-    /// handle and opens a fresh one synchronously (CloseHandle/CreateFileW
-    /// are fast on Windows — no in-flight CDB to drain like Linux SG_IO).
-    /// On success, `self.handle` is replaced and the next `execute()` call
-    /// uses the new handle. On failure, `self.handle` is set to
-    /// INVALID_HANDLE_VALUE and subsequent calls return `DeviceNotFound`.
-    fn try_recover(&mut self) {
-        if self.handle != INVALID_HANDLE_VALUE {
-            unsafe { CloseHandle(self.handle) };
-        }
-        let new_handle = unsafe {
-            CreateFileW(
-                self.wide_path.as_ptr(),
-                GENERIC_READ | GENERIC_WRITE,
-                FILE_SHARE_READ | FILE_SHARE_WRITE,
-                std::ptr::null(),
-                OPEN_EXISTING,
-                FILE_ATTRIBUTE_NORMAL,
-                std::ptr::null(),
-            )
-        };
-        self.handle = new_handle;
+        Ok(SptiTransport { handle })
     }
 
     /// Reset the drive to a known good state.
@@ -259,7 +228,7 @@ pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
         crate::scsi::TUR_TIMEOUT_MS,
     ) {
         Ok(_) => Ok(true),
-        Err(Error::ScsiError { sense_key: 2, .. }) => Ok(false),
+        Err(ref e) if e.scsi_sense().is_some_and(|s| s.is_not_ready()) => Ok(false),
         Err(e) => Err(e),
     }
 }
@@ -282,15 +251,6 @@ impl ScsiTransport for SptiTransport {
         data: &mut [u8],
         timeout_ms: u32,
     ) -> Result<ScsiResult> {
-        // Per RIP_DESIGN.md §15.1: parity with Linux's recovery contract.
-        // If a prior call invalidated the handle and try_recover() also
-        // failed, fail fast.
-        if self.handle == INVALID_HANDLE_VALUE {
-            return Err(Error::DeviceNotFound {
-                path: String::new(),
-            });
-        }
-
         // Zero the data buffer for reads to prevent returning uninitialized data
         // if the driver doesn't fully update DataTransferLength.
         if direction == DataDirection::FromDevice {
@@ -339,29 +299,34 @@ impl ScsiTransport for SptiTransport {
         };
 
         if ok == 0 {
-            // Driver-level failure (timeout, handle gone, etc.). Recover
-            // the handle so the caller's retry loop can resume — same
-            // observable contract as Linux's async fd recovery, but
-            // synchronous because Windows's CloseHandle/CreateFileW don't
-            // block on in-flight CDBs.
-            self.try_recover();
+            // Driver-level failure (timeout, handle gone, etc.). Bubble
+            // up; in-library handle recovery was removed in 0.13.20 along
+            // with Linux's async fd-recovery and macOS's `try_recover` —
+            // the kernel mid-layer already did its escalation by the time
+            // DeviceIoControl returned, and re-issuing reset/reopen here
+            // is at best redundant and at worst deepens the wedge. Caller
+            // surfaces the failure to UX.
             return Err(Error::ScsiError {
                 opcode: cdb[0],
-                status: 0xFF,
-                sense_key: 0,
+                status: super::SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
             });
         }
 
         if sptwb.spt.ScsiStatus != 0 {
-            let sense_key = if sptwb.sense[2] != 0 {
-                sptwb.sense[2] & 0x0F
-            } else {
-                0
-            };
+            // SPTI doesn't surface a "bytes written into sense buffer"
+            // count separate from SenseInfoLength (input). Pass the full
+            // K_SENSE_SIZE; parse_sense keys off byte 0's response code
+            // to handle descriptor (0x72/0x73) vs fixed (0x70/0x71).
+            //
+            // 0.13.23: carry the full SPC-4 sense triple in
+            // `Error::ScsiError::sense` so callers can route on
+            // `ScsiSense::is_medium_error()` etc.
+            let parsed = super::parse_sense(&sptwb.sense, K_SENSE_SIZE as u8);
             return Err(Error::ScsiError {
                 opcode: cdb[0],
                 status: sptwb.spt.ScsiStatus,
-                sense_key,
+                sense: Some(parsed),
             });
         }
 

src/sector.rs

@@ -24,6 +24,8 @@ pub trait SectorReader: Send {
     fn capacity(&self) -> u32 {
         0
     }
+
+    fn set_speed(&mut self, _kbs: u16) {}
 }
 
 /// SectorReader backed by a file (ISO image).

src/udf.rs

@@ -278,10 +278,11 @@ impl UdfFs {
     /// The data_lba is partition-relative.
     fn read_icb_extent(&self, reader: &mut dyn SectorReader, meta_lba: u32) -> Result<(u32, u32)> {
         let extents = self.read_icb_extents(reader, meta_lba)?;
-        extents
-            .first()
-            .copied()
-            .ok_or(Error::DiscRead { sector: 0 })
+        extents.first().copied().ok_or(Error::DiscRead {
+            sector: 0,
+            status: None,
+            sense: None,
+        })
     }
 
     /// Read ALL allocation extents for a file from its ICB.
@@ -307,6 +308,8 @@ impl UdfFs {
                 if ad_offset + l_ad > icb.len() {
                     return Err(Error::DiscRead {
                         sector: self.meta_to_abs(meta_lba) as u64,
+                        status: None,
+                        sense: None,
                     });
                 }
                 (ad_offset, l_ad)
@@ -319,11 +322,19 @@ impl UdfFs {
                 if ad_offset + l_ad > icb.len() {
                     return Err(Error::DiscRead {
                         sector: self.meta_to_abs(meta_lba) as u64,
+                        status: None,
+                        sense: None,
                     });
                 }
                 (ad_offset, l_ad)
             }
-            _ => return Err(Error::DiscRead { sector: 0 }),
+            _ => {
+                return Err(Error::DiscRead {
+                    sector: 0,
+                    status: None,
+                    sense: None,
+                });
+            }
         };
 
         let mut extents = Vec::new();
@@ -414,7 +425,11 @@ pub fn read_filesystem(reader: &mut dyn SectorReader) -> Result<UdfFs> {
 
     let tag_id = u16::from_le_bytes([avdp[0], avdp[1]]);
     if tag_id != 2 {
-        return Err(Error::DiscRead { sector: 0 });
+        return Err(Error::DiscRead {
+            sector: 0,
+            status: None,
+            sense: None,
+        });
     }
 
     // Main VDS extent location: bytes [16:20] = LBA, [20:24] = length
@@ -455,14 +470,22 @@ pub fn read_filesystem(reader: &mut dyn SectorReader) -> Result<UdfFs> {
     }
 
     if partition_start == 0 {
-        return Err(Error::DiscRead { sector: 0 });
+        return Err(Error::DiscRead {
+            sector: 0,
+            status: None,
+            sense: None,
+        });
     }
 
     // Step 3: Parse partition maps from LVD to find metadata partition
     // BD-ROM discs (UDF 2.50) use a metadata partition (Type 2 map with "*UDF Metadata Partition")
     // The metadata file is stored at lba=0 of the physical partition
     let metadata_start = if num_partition_maps >= 2 {
-        let lvd_sec = lvd_sector.ok_or(Error::DiscRead { sector: 0 })?;
+        let lvd_sec = lvd_sector.ok_or(Error::DiscRead {
+            sector: 0,
+            status: None,
+            sense: None,
+        })?;
 
         // Read LVD to check partition map type
         let mut lvd = [0u8; 2048];
@@ -497,6 +520,8 @@ pub fn read_filesystem(reader: &mut dyn SectorReader) -> Result<UdfFs> {
                     if ad_off + 8 > meta_icb.len() {
                         return Err(Error::DiscRead {
                             sector: meta_file_lba as u64,
+                            status: None,
+                            sense: None,
                         });
                     }
                     let ad_len = u32::from_le_bytes([
@@ -536,7 +561,11 @@ pub fn read_filesystem(reader: &mut dyn SectorReader) -> Result<UdfFs> {
 
     let fsd_tag = u16::from_le_bytes([fsd[0], fsd[1]]);
     if fsd_tag != 256 {
-        return Err(Error::DiscRead { sector: 0 });
+        return Err(Error::DiscRead {
+            sector: 0,
+            status: None,
+            sense: None,
+        });
     }
 
     // Root Directory ICB: long_ad at FSD offset 400
@@ -585,6 +614,8 @@ fn read_directory(
             if ad_off + 8 > icb.len() {
                 return Err(Error::DiscRead {
                     sector: (meta_start + meta_lba) as u64,
+                    status: None,
+                    sense: None,
                 });
             }
             let len = u32::from_le_bytes([
@@ -607,6 +638,8 @@ fn read_directory(
             if ad_off + 8 > icb.len() {
                 return Err(Error::DiscRead {
                     sector: (meta_start + meta_lba) as u64,
+                    status: None,
+                    sense: None,
                 });
             }
             let len = u32::from_le_bytes([

tests/integration_progress_and_halt.rs

@@ -351,7 +351,7 @@ fn test_file_sector_reader_round_trip() {
 //
 // Per RIP_DESIGN.md §2.1 + §3: Disc::copy must reach the end of the disc
 // regardless of how many reads fail. The only legitimate early exit is the
-// halt flag. With `skip_on_error + skip_forward` and a reader that returns
+// halt flag. With `skip_on_error` and a reader that returns
 // Err for every read, Pass 1 must:
 //   - mark every sector NonTrimmed (so Pass 2 can retry them)
 //   - return cleanly (no panic, no hang)
@@ -392,7 +392,7 @@ impl FailingSectorReader {
 impl SectorReader for FailingSectorReader {
     fn read_sectors(
         &mut self,
-        lba: u32,
+        _lba: u32,
         _count: u16,
         _buf: &mut [u8],
         _recovery: bool,
@@ -400,7 +400,20 @@ impl SectorReader for FailingSectorReader {
         if let Some(h) = self.halt_on_first_read.take() {
             h.store(true, Ordering::Relaxed);
         }
-        Err(libfreemkv::error::Error::DiscRead { sector: lba as u64 })
+        // Model what a real damaged-disc read returns: CHECK CONDITION +
+        // MEDIUM ERROR (sense_key 3, ASC 0x11 UNRECOVERED READ ERROR,
+        // ASCQ 0x05 L-EC UNCORRECTABLE). Disc::copy's hysteresis must
+        // engage on this — `Error::DiscRead` is libfreemkv's own
+        // post-classification signal, not what a real reader emits.
+        Err(libfreemkv::error::Error::ScsiError {
+            opcode: libfreemkv::scsi::SCSI_READ_10,
+            status: libfreemkv::scsi::SCSI_STATUS_CHECK_CONDITION,
+            sense: Some(libfreemkv::ScsiSense {
+                sense_key: libfreemkv::scsi::SENSE_KEY_MEDIUM_ERROR,
+                asc: 0x11,
+                ascq: 0x05,
+            }),
+        })
     }
 
     fn capacity(&self) -> u32 {
@@ -411,7 +424,7 @@ impl SectorReader for FailingSectorReader {
 #[test]
 fn test_disc_copy_completes_full_disc_with_failing_reader() {
     // 1024 sectors = 2 MB. Reader fails every read. With skip_on_error +
-    // skip_forward, Pass 1 must mark every sector NonTrimmed and return
+    // skip_on_error, Pass 1 must mark every sector NonTrimmed and return
     // cleanly — no bail, no hang.
     let capacity_sectors: u32 = 1024;
     let total_bytes: u64 = capacity_sectors as u64 * SECTOR_SIZE as u64;
@@ -425,8 +438,8 @@ fn test_disc_copy_completes_full_disc_with_failing_reader() {
 
     let opts = CopyOptions {
         decrypt: false,
-        skip_on_error: true,
-        skip_forward: true,
+        multipass: true,
+
         ..Default::default()
     };
 
@@ -441,9 +454,7 @@ fn test_disc_copy_completes_full_disc_with_failing_reader() {
     let _ = std::fs::remove_file(libfreemkv::disc::mapfile_path_for(&iso_path));
 
     // Hard bound — even at 0 ms per read, 1024 sectors with skip-forward
-    // should complete in well under a second on any host. If this test runs
-    // for minutes, something has regressed (e.g. stall guard reintroduced
-    // with infinite-loop semantics, or Pass 1 is hanging on each read).
+    // should complete in well under a second on any host.
     assert!(
         elapsed < Duration::from_secs(5),
         "Pass 1 took {elapsed:?} on a 2 MB synthetic disc — expected < 5 s"
@@ -507,8 +518,8 @@ fn test_disc_copy_halts_promptly_on_failing_reader() {
 
     let opts = CopyOptions {
         decrypt: false,
-        skip_on_error: true,
-        skip_forward: true,
+        multipass: true,
+
         halt: Some(halt),
         ..Default::default()
     };
@@ -537,3 +548,89 @@ fn test_disc_copy_halts_promptly_on_failing_reader() {
         "halt fired before sweep completed; bytes_pending must be > 0"
     );
 }
+
+// ── 8. Hysteresis recovers data the drive can read individually ──────────
+//
+// Pass 1 reads in batch (32 sectors = 1 ECC block). Failed blocks are marked
+// NonTrimmed for Pass 2 recovery. This test verifies that a reader where every
+// multi-sector read fails produces all NonTrimmed output with zero bytes_good.
+
+struct BlockSizeFailingReader {
+    capacity: u32,
+}
+
+impl SectorReader for BlockSizeFailingReader {
+    fn read_sectors(
+        &mut self,
+        lba: u32,
+        count: u16,
+        buf: &mut [u8],
+        _recovery: bool,
+    ) -> Result<usize> {
+        if count == 1 {
+            for chunk in buf.chunks_mut(SECTOR_SIZE) {
+                chunk.fill((lba & 0xff) as u8);
+            }
+            Ok(buf.len())
+        } else {
+            Err(libfreemkv::error::Error::ScsiError {
+                opcode: libfreemkv::scsi::SCSI_READ_10,
+                status: libfreemkv::scsi::SCSI_STATUS_CHECK_CONDITION,
+                sense: Some(libfreemkv::ScsiSense {
+                    sense_key: libfreemkv::scsi::SENSE_KEY_MEDIUM_ERROR,
+                    asc: 0x11,
+                    ascq: 0x00,
+                }),
+            })
+        }
+    }
+
+    fn capacity(&self) -> u32 {
+        self.capacity
+    }
+}
+
+#[test]
+fn test_disc_copy_marks_failed_ecc_blocks_as_nontrimmed() {
+    let capacity_sectors: u32 = 256;
+    let total_bytes: u64 = capacity_sectors as u64 * SECTOR_SIZE as u64;
+
+    let mut reader = BlockSizeFailingReader {
+        capacity: capacity_sectors,
+    };
+    let disc = synthetic_disc(capacity_sectors);
+
+    let tmp = tempfile::NamedTempFile::new().expect("tempfile create");
+    let iso_path = tmp.path().to_path_buf();
+    drop(tmp);
+
+    let opts = CopyOptions {
+        decrypt: false,
+        multipass: true,
+
+        ..Default::default()
+    };
+
+    let result = disc
+        .copy(&mut reader, &iso_path, &opts)
+        .expect("copy returns Ok");
+
+    let _ = std::fs::remove_file(&iso_path);
+    let _ = std::fs::remove_file(libfreemkv::disc::mapfile_path_for(&iso_path));
+
+    // Pass 1 reads every batch at bpt=32 (no batch reduction, no skip-ahead).
+    // BlockSizeFailingReader fails on all batch=32 reads, so every sector
+    // is marked NonTrimmed. bytes_good=0 is correct — Pass 2 recovers them.
+    assert_eq!(
+        result.bytes_good, 0,
+        "Pass 1 at bpt=32 should not recover any sectors when all batches fail"
+    );
+    assert!(
+        result.bytes_pending > 0,
+        "all sectors should be NonTrimmed pending Pass 2"
+    );
+    assert!(
+        !result.complete,
+        "complete=false when sectors remain NonTrimmed"
+    );
+}

tests/scsi_error_decoding.rs

@@ -0,0 +1,391 @@
+//! Integration tests for the SCSI error-decoding contract.
+//!
+//! v0.13.20 rewrote `scsi/linux.rs` to a synchronous blocking SG_IO and
+//! consolidated sense parsing into the `parse_sense` helper that every
+//! platform backend now shares. v0.13.23 replaced the `Error::ScsiError`
+//! flat-fields shape with `{ opcode, status, sense: Option<ScsiSense> }`
+//! so callers can route on structured sense data (key + ASC + ASCQ) via
+//! [`Error::scsi_sense`] / [`Error::is_marginal_read`] /
+//! [`ScsiSense::is_*`].
+//!
+//! The actual `ioctl(SG_IO, ...)` call is impossible to mock without a
+//! kernel — see
+//! `(internal)/docs/audits/2026-04-26-scsi-architecture-research.md`
+//! for why the audit recommends against libc shims here. These tests
+//! therefore pin the *contract* every backend must satisfy via a mock
+//! `ScsiTransport`:
+//!
+//!   1. Healthy result → `Ok(ScsiResult { bytes_transferred = data.len() - resid })`.
+//!   2. Transport-level failure (no SCSI status delivered: kernel
+//!      timeout, USB bridge wedge, IOKit service error) →
+//!      `Error::ScsiError { status: SCSI_STATUS_TRANSPORT_FAILURE, sense: None }`.
+//!      `Error::is_scsi_transport_failure()` returns `true`. Used by
+//!      `drive_has_disc` to detect the wedge signature.
+//!   3. SCSI-level failure (drive replied CHECK CONDITION with sense) →
+//!      `Error::ScsiError { status: 0x02, sense: Some(ScsiSense {…}) }`
+//!      with the parsed key/ASC/ASCQ.
+//!   4. `Error::is_marginal_read()` is `true` for MEDIUM ERROR /
+//!      ABORTED COMMAND / RECOVERED ERROR / NO SENSE; `false` for
+//!      HARDWARE / DATA PROTECT / UNIT ATTENTION / NOT READY / ILLEGAL
+//!      REQUEST and for transport failures.
+//!
+//! Inline `parse_sense_tests` in `src/scsi/mod.rs` cover the pure parse
+//! logic (descriptor 0x72/0x73 vs fixed 0x70/0x71, short-buffer, VALID
+//! bit masking, unknown response codes, ASC/ASCQ offsets); this file
+//! covers the consumer side — a real transport feeding a real Error
+//! variant to a real call site (`scsi::inquiry`).
+
+use libfreemkv::error::Error;
+use libfreemkv::scsi::{
+    DataDirection, SCSI_STATUS_CHECK_CONDITION, SCSI_STATUS_TRANSPORT_FAILURE,
+    SENSE_KEY_ABORTED_COMMAND, SENSE_KEY_DATA_PROTECT, SENSE_KEY_HARDWARE_ERROR,
+    SENSE_KEY_ILLEGAL_REQUEST, SENSE_KEY_MEDIUM_ERROR, SENSE_KEY_NOT_READY,
+    SENSE_KEY_RECOVERED_ERROR, SENSE_KEY_UNIT_ATTENTION, ScsiResult, ScsiSense, ScsiTransport,
+};
+
+/// A scripted ScsiTransport. Each `execute()` consumes the next entry
+/// from `script` and returns the corresponding outcome.
+///
+/// Outcomes mirror what each backend's `execute()` should produce after
+/// the v0.13.23 sense plumbing: `Option<ScsiSense>` carrying the full
+/// SPC-4 triple for drive-reported failures, `None` for transport-level
+/// failures.
+struct MockTransport {
+    script: Vec<MockOutcome>,
+    next: usize,
+}
+
+#[derive(Clone)]
+enum MockOutcome {
+    /// Healthy completion. `data` is what the transport wrote into the
+    /// caller's data buffer (truncated to the buffer length); `resid`
+    /// is reported back as `data.len() - bytes_transferred`.
+    Ok { data: Vec<u8>, resid: i32 },
+    /// Transport-level failure: `hdr.host_status = DID_TIME_OUT` on
+    /// Linux, `kIOReturnError` on macOS, `DeviceIoControl` returning 0
+    /// on Windows. Backends synthesise `SCSI_STATUS_TRANSPORT_FAILURE`
+    /// with `sense = None`.
+    TransportFailure,
+    /// Drive replied with sense data (typically `SCSI_STATUS_CHECK_CONDITION`
+    /// + a populated sense buffer).
+    ScsiFailure { status: u8, sense: ScsiSense },
+}
+
+impl MockTransport {
+    fn new(script: Vec<MockOutcome>) -> Self {
+        Self { script, next: 0 }
+    }
+}
+
+impl ScsiTransport for MockTransport {
+    fn execute(
+        &mut self,
+        cdb: &[u8],
+        _direction: DataDirection,
+        data: &mut [u8],
+        _timeout_ms: u32,
+    ) -> libfreemkv::error::Result<ScsiResult> {
+        let i = self.next;
+        self.next += 1;
+        let outcome = self
+            .script
+            .get(i)
+            .cloned()
+            .expect("MockTransport script ran out — test wrote fewer outcomes than calls");
+        match outcome {
+            MockOutcome::Ok { data: d, resid } => {
+                let n = d.len().min(data.len());
+                data[..n].copy_from_slice(&d[..n]);
+                let bytes = (data.len() as i32).saturating_sub(resid).max(0) as usize;
+                Ok(ScsiResult {
+                    status: 0,
+                    bytes_transferred: bytes,
+                    sense: [0u8; 32],
+                })
+            }
+            MockOutcome::TransportFailure => Err(Error::ScsiError {
+                opcode: cdb[0],
+                status: SCSI_STATUS_TRANSPORT_FAILURE,
+                sense: None,
+            }),
+            MockOutcome::ScsiFailure { status, sense } => Err(Error::ScsiError {
+                opcode: cdb[0],
+                status,
+                sense: Some(sense),
+            }),
+        }
+    }
+}
+
+/// Helper — build a CHECK CONDITION outcome with a given sense key
+/// and zero ASC/ASCQ. Most consumer-side tests only care about the key.
+fn check_cond(sense_key: u8) -> MockOutcome {
+    MockOutcome::ScsiFailure {
+        status: SCSI_STATUS_CHECK_CONDITION,
+        sense: ScsiSense {
+            sense_key,
+            asc: 0,
+            ascq: 0,
+        },
+    }
+}
+
+// ── 1. Healthy read ───────────────────────────────────────────────────────
+
+#[test]
+fn test_healthy_inquiry_returns_ok_with_full_transfer() {
+    // Build a fake INQUIRY response (96 bytes per scsi::inquiry).
+    // Vendor "TEST-VND", model "TEST-MODEL ", firmware "1.00".
+    let mut payload = vec![0u8; 96];
+    payload[8..16].copy_from_slice(b"TEST-VND");
+    payload[16..32].copy_from_slice(b"TEST-MODEL      ");
+    payload[32..36].copy_from_slice(b"1.00");
+
+    let mut transport = MockTransport::new(vec![MockOutcome::Ok {
+        data: payload,
+        resid: 0,
+    }]);
+
+    let r = libfreemkv::scsi::inquiry(&mut transport).expect("inquiry should succeed");
+    assert_eq!(r.vendor_id, "TEST-VND");
+    assert_eq!(r.model, "TEST-MODEL");
+    assert_eq!(r.firmware, "1.00");
+}
+
+// ── 2. Transport-level failure: no SCSI status, no sense data ─────────────
+
+#[test]
+fn test_transport_failure_surfaces_with_sense_none() {
+    let mut transport = MockTransport::new(vec![MockOutcome::TransportFailure]);
+
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+    assert!(
+        err.is_scsi_transport_failure(),
+        "TransportFailure must satisfy is_scsi_transport_failure()"
+    );
+    assert!(
+        err.scsi_sense().is_none(),
+        "transport failure has no sense data"
+    );
+    assert!(
+        !err.is_marginal_read(),
+        "transport failure must not be classified as marginal-read"
+    );
+    match err {
+        Error::ScsiError { status, sense, .. } => {
+            assert_eq!(status, SCSI_STATUS_TRANSPORT_FAILURE);
+            assert!(sense.is_none());
+        }
+        other => panic!("expected ScsiError, got {other:?}"),
+    }
+}
+
+// ── 3. CHECK CONDITION + ILLEGAL REQUEST ──────────────────────────────────
+
+#[test]
+fn test_check_cond_illegal_request_carries_sense() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_ILLEGAL_REQUEST)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert_eq!(sense.sense_key, SENSE_KEY_ILLEGAL_REQUEST);
+    assert!(sense.is_illegal_request());
+    assert!(!err.is_marginal_read(), "ILLEGAL REQUEST is not marginal");
+    assert!(!err.is_scsi_transport_failure());
+}
+
+// ── 4. CHECK CONDITION + NOT READY (drive_has_disc relies on this) ────────
+
+#[test]
+fn test_check_cond_not_ready_predicate() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_NOT_READY)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_not_ready(), "sense_key 2 ⇒ is_not_ready");
+    assert!(!err.is_marginal_read(), "NOT READY is not marginal");
+}
+
+// ── 5. CHECK CONDITION + MEDIUM ERROR (canonical marginal-read) ───────────
+
+#[test]
+fn test_check_cond_medium_error_is_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_MEDIUM_ERROR)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_medium_error());
+    assert!(sense.is_marginal());
+    assert!(
+        err.is_marginal_read(),
+        "MEDIUM ERROR is the canonical marginal-read signal"
+    );
+}
+
+// ── 6. CHECK CONDITION + ABORTED COMMAND (also marginal) ──────────────────
+
+#[test]
+fn test_check_cond_aborted_command_is_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_ABORTED_COMMAND)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_aborted_command());
+    assert!(err.is_marginal_read(), "ABORTED COMMAND is marginal");
+}
+
+// ── 7. CHECK CONDITION + RECOVERED ERROR (drive recovered; marginal) ──────
+
+#[test]
+fn test_check_cond_recovered_error_is_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_RECOVERED_ERROR)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+    assert!(
+        err.is_marginal_read(),
+        "RECOVERED ERROR is treated as marginal (drive recovered, retry-friendly class)"
+    );
+}
+
+// ── 8. CHECK CONDITION + HARDWARE ERROR (NOT marginal — bail) ─────────────
+
+#[test]
+fn test_check_cond_hardware_error_not_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_HARDWARE_ERROR)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_hardware_error());
+    assert!(
+        !err.is_marginal_read(),
+        "HARDWARE ERROR must not be marginal — drive failing, retry can't help"
+    );
+}
+
+// ── 9. CHECK CONDITION + DATA PROTECT (NOT marginal — bail) ───────────────
+
+#[test]
+fn test_check_cond_data_protect_not_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_DATA_PROTECT)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_data_protect());
+    assert!(
+        !err.is_marginal_read(),
+        "DATA PROTECT (AACS / region) must not be marginal — retry can't help"
+    );
+}
+
+// ── 10. CHECK CONDITION + UNIT ATTENTION (NOT marginal — caller rescans) ──
+
+#[test]
+fn test_check_cond_unit_attention_not_marginal() {
+    let mut transport = MockTransport::new(vec![check_cond(SENSE_KEY_UNIT_ATTENTION)]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("CHECK CONDITION must carry sense");
+    assert!(sense.is_unit_attention());
+    assert!(
+        !err.is_marginal_read(),
+        "UNIT ATTENTION must not be marginal — caller should rescan, not retry"
+    );
+}
+
+// ── 11. ASC/ASCQ propagate from sense buffer to ScsiError.sense ───────────
+
+#[test]
+fn test_asc_ascq_round_trip_through_error() {
+    let outcome = MockOutcome::ScsiFailure {
+        status: SCSI_STATUS_CHECK_CONDITION,
+        sense: ScsiSense {
+            sense_key: SENSE_KEY_MEDIUM_ERROR,
+            asc: 0x11,
+            ascq: 0x05, // L-EC UNCORRECTABLE
+        },
+    };
+    let mut transport = MockTransport::new(vec![outcome]);
+    let err = libfreemkv::scsi::inquiry(&mut transport).unwrap_err();
+
+    let sense = err.scsi_sense().expect("must carry sense");
+    assert_eq!(sense.sense_key, SENSE_KEY_MEDIUM_ERROR);
+    assert_eq!(sense.asc, 0x11);
+    assert_eq!(sense.ascq, 0x05);
+}
+
+// ── 12. Healthy short transfer (resid > 0) ────────────────────────────────
+
+#[test]
+fn test_healthy_short_transfer_reports_partial_bytes() {
+    // Transport reported back fewer bytes than requested (resid = 16).
+    // For a 96-byte buffer that means bytes_transferred = 80.
+    let payload = vec![0u8; 96];
+    let mut transport = MockTransport::new(vec![MockOutcome::Ok {
+        data: payload,
+        resid: 16,
+    }]);
+
+    let cdb = [libfreemkv::scsi::SCSI_INQUIRY, 0, 0, 0, 0x60, 0];
+    let mut buf = [0u8; 96];
+    let r = transport
+        .execute(&cdb, DataDirection::FromDevice, &mut buf, 1_000)
+        .expect("ok");
+    assert_eq!(r.status, 0);
+    assert_eq!(
+        r.bytes_transferred, 80,
+        "bytes_transferred must equal data.len() - resid"
+    );
+}
+
+// ── 13. Error::Display does not leak English in the SCSI variant ──────────
+//
+// Library rule (project docs): no English in error display, only "E{code}"
+// + structured data. Regression guard for the SCSI variant specifically
+// because it's the most-emitted error in the rip path.
+
+#[test]
+fn test_scsi_error_display_format_is_codes_only() {
+    let err = Error::ScsiError {
+        opcode: 0x12,
+        status: SCSI_STATUS_CHECK_CONDITION,
+        sense: Some(ScsiSense {
+            sense_key: SENSE_KEY_ILLEGAL_REQUEST,
+            asc: 0x24,
+            ascq: 0x00,
+        }),
+    };
+    let s = err.to_string();
+    assert!(
+        s.starts_with("E4000:"),
+        "ScsiError must lead with E4000: {s}"
+    );
+    assert!(
+        s.contains("0x12") && s.contains("0x02") && s.contains("0x05") && s.contains("0x24"),
+        "ScsiError must show opcode/status/key/asc in hex: {s}"
+    );
+    // Crude English filter — same as the inline error.rs::display test.
+    for word in s.split(|c: char| !c.is_ascii_alphabetic()) {
+        assert!(
+            word.len() <= 4,
+            "ScsiError display contains suspicious word `{word}`: {s}"
+        );
+    }
+}
+
+// ── 14. Transport-failure Display omits sense fields ──────────────────────
+
+#[test]
+fn test_scsi_transport_failure_display_short_form() {
+    let err = Error::ScsiError {
+        opcode: 0x28,
+        status: SCSI_STATUS_TRANSPORT_FAILURE,
+        sense: None,
+    };
+    let s = err.to_string();
+    assert!(s.starts_with("E4000:"));
+    assert!(s.contains("0x28") && s.contains("0xff"));
+    // No sense triple should appear in the no-sense form.
+    assert!(
+        !s.contains("0x00/0x00/0x00"),
+        "transport failure must not carry phantom sense: {s}"
+    );
+}

tests/scsi_recovery.rs

@@ -0,0 +1,115 @@
+//! Tests for SgIoTransport timeout recovery (Fix 2).
+//!
+//! When `execute()` detects a transport-level failure (kernel timeout /
+//! USB bridge wedge — `host_status != 0`), it spawns two background
+//! threads to (1) close the old fd and (2) open a fresh one, then
+//! stores the new fd in `fd_recovery`. The next `execute()` call picks
+//! up the recovered fd without blocking on close().
+//!
+//! These tests require a real /dev/sg* device and are therefore #[ignore].
+
+use libfreemkv::scsi::{DataDirection, SCSI_STATUS_TRANSPORT_FAILURE};
+use std::path::Path;
+use std::time::Duration;
+
+#[test]
+#[ignore]
+fn test_sgio_transport_timeout_does_not_kill_transport() {
+    let device = "/dev/sg2";
+    let device = std::env::var("FREEMKV_TEST_SG_DEVICE").unwrap_or(device.to_string());
+    let path = Path::new(&device);
+
+    #[cfg(target_os = "linux")]
+    {
+        use libfreemkv::scsi::ScsiTransport;
+        use libfreemkv::scsi::linux::SgIoTransport;
+        use std::sync::Arc;
+        use std::sync::atomic::{AtomicI32, Ordering};
+
+        let mut transport = SgIoTransport::open(path).expect("open device");
+        let fd_before = transport.fd;
+
+        // READ_10 with 1 ms timeout to force kernel timeout.
+        let cdb = [0x28, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00];
+        let mut data = vec![0u8; 2048];
+
+        let start = std::time::Instant::now();
+        let result = transport.execute(&cdb, DataDirection::FromDevice, &mut data, 1);
+        let _elapsed = start.elapsed();
+
+        assert!(result.is_err(), "expected Err on timeout, got {:?}", result);
+        let err = result.unwrap_err();
+        assert!(
+            matches!(&err, libfreemkv::Error::ScsiError { status, .. } if *status == SCSI_STATUS_TRANSPORT_FAILURE),
+            "expected ScsiError(TRANSPORT_FAILURE), got {:?}",
+            err
+        );
+        assert_eq!(transport.fd, -1, "fd should be -1 after timeout");
+
+        // Wait for recovery thread to store new fd.
+        let recovered = Arc::new(AtomicI32::new(-1));
+        let recovery_ref = transport.fd_recovery.clone();
+        for _ in 0..100 {
+            let v = recovery_ref.load(Ordering::Acquire);
+            if v >= 0 {
+                recovered.store(v, Ordering::Release);
+                break;
+            }
+            std::thread::sleep(Duration::from_millis(50));
+        }
+        let new_fd = recovered.load(Ordering::Acquire);
+        assert!(new_fd >= 0, "recovery thread should have produced a new fd");
+
+        // Next execute() must pick up recovered fd quickly.
+        let mut data2 = vec![0u8; 2048];
+        let start2 = std::time::Instant::now();
+        let result2 = transport.execute(&cdb, DataDirection::FromDevice, &mut data2, 5000);
+        let elapsed2 = start2.elapsed();
+
+        assert!(
+            result2.is_ok(),
+            "execute() with recovered fd should succeed, got {:?}",
+            result2
+        );
+        assert!(
+            elapsed2 < Duration::from_secs(2),
+            "should return quickly, took {:?}",
+            elapsed2
+        );
+        assert_ne!(transport.fd, -1, "fd should be valid after recovery");
+        assert_ne!(transport.fd, fd_before, "fd should be fresh after recovery");
+    }
+    #[cfg(not(target_os = "linux"))]
+    {
+        eprintln!("SKIP: test requires Linux / SgIoTransport");
+    }
+}
+
+#[test]
+#[ignore]
+fn test_drive_read_per_cdb_timeout_bounds_call() {
+    let device = "/dev/sg2";
+    let device = std::env::var("FREEMKV_TEST_SG_DEVICE").unwrap_or(device.to_string());
+    let path = Path::new(&device);
+
+    #[cfg(target_os = "linux")]
+    {
+        let mut drive = libfreemkv::Drive::open(path).expect("open drive");
+        let timeout_ms: u32 = 5_000;
+
+        let start = std::time::Instant::now();
+        let _ = drive.read(0, 1, &mut [0u8; 2048], false);
+        let elapsed = start.elapsed();
+
+        let overhead = Duration::from_millis(500);
+        assert!(
+            elapsed < Duration::from_millis(timeout_ms as u64) + overhead,
+            "Drive::read should return within timeout_ms + overhead, took {:?}",
+            elapsed
+        );
+    }
+    #[cfg(not(target_os = "linux"))]
+    {
+        eprintln!("SKIP: test requires Linux / SgIoTransport");
+    }
+}