Clean pipeline: one open, one init, no double-init

- Removed open_unlocked() — open() is the only entry
- Removed redundant init() call from open_title()
- init() called once in open(), handles everything
- Each function does one thing: open→init→scan→read

src/disc.rs

@@ -798,9 +798,7 @@ impl Disc {
             detail: format!("title index {} out of range (have {})", title_idx, self.titles.len()),
         })?;
 
-        if !session.is_unlocked() {
-            let _ = session.init();
-        }
+        // init() already called by DriveSession::open(). No re-init needed.
 
         let speed_cdb = crate::scsi::build_set_cd_speed(0xFFFF);
         let mut dummy = [0u8; 0];

src/drive.rs

@@ -30,10 +30,11 @@ pub struct DriveSession {
 }
 
 impl DriveSession {
-    /// Open a drive — identify, wait for disc, and unlock for raw reads.
     ///
-    /// This is the standard entry point. After `open()`, the drive is
-    /// ready for scanning and content reads.
+    /// This is the only entry point. After `open()`, the drive is
+    /// ready for scanning and content reads. init() handles everything:
+    /// unlock, firmware upload if needed, calibration, registers.
+    /// Called once per session. Non-fatal if init fails (BD works without it).
     pub fn open(device: &Path) -> Result<Self> {
         let mut session = Self::open_no_unlock(device)?;
         session.wait_ready()?;
@@ -41,17 +42,6 @@ impl DriveSession {
         Ok(session)
     }
 
-    /// Open a drive and immediately init for raw reads.
-    ///
-    /// Use this when you need raw disc access without AACS (e.g. capture,
-    /// sector dumps). Skips AACS authentication — cannot be done after init.
-    pub fn open_unlocked(device: &Path) -> Result<Self> {
-        let mut session = Self::open_no_unlock(device)?;
-        session.wait_ready()?;
-        let _ = session.init();
-        Ok(session)
-    }
-
     /// Open a drive — identify only, no wait, no unlock.
     ///
     /// Low-level entry point. Caller is responsible for wait_ready()

src/platform/mt1959.rs

@@ -463,11 +463,21 @@ impl Platform for Mt1959 {
     ///   Phase 5: cmd 9 × 6 retries (status)
     fn init(&mut self, scsi: &mut dyn ScsiTransport) -> Result<()> {
         // Phase 1: Unlock + firmware upload (6 retries)
+        //
+        // Three unlock outcomes:
+        //   Ok → warm drive, firmware loaded, skip to calibrate
+        //   Err(other) → cold drive or SCSI error, try load_firmware
         let mut unlocked = false;
         for _attempt in 0..6 {
             match self.unlock(scsi) {
                 Ok(_) => { unlocked = true; break; }
+                Err(Error::SignatureMismatch { .. }) => {
+                    return Err(Error::UnlockFailed {
+                        detail: "signature mismatch — wrong profile for this drive".into(),
+                    });
+                }
                 Err(_) => {
+                    // Cold boot or SCSI error — try uploading firmware
                     if self.load_firmware(scsi).is_ok() {
                         unlocked = true;
                         break;
@@ -493,17 +503,12 @@ impl Platform for Mt1959 {
             return Err(Error::ScsiError { opcode: 0x3C, status: 0xFF, sense_key: 0 });
         }
 
-        // If fails: cmd 5 fallback (keepalive)
-        // In our context: this fetches a display string, not critical for reads
-        let _ = self.probe(scsi, 0x00, 0, 0x3FF);
+        // Phase 3: Read registers — non-fatal
+        // x86 retries 5×, but we do a single attempt each. Not required for reads.
+        let _ = self.read_register_a(scsi);
+        let _ = self.read_register_b(scsi);
 
-        for _attempt in 0..5 {
-            let a_ok = self.read_register_a(scsi).is_ok();
-            let b_ok = self.read_register_b(scsi).is_ok();
-            if a_ok && b_ok { break; }
-        }
-
-        // Phase 5: Status — non-fatal, single attempt
+        // Phase 4: Status — non-fatal, single attempt
         // Some drives reject sub_cmd 0x13. Not required for reads.
         let _ = self.status(scsi);