fix(textstream): 快照前缀被改写时保留权威全文，不再中止整条转写

openless-all/app/src-tauri/src/asr/local/experimental/textstream/test_worker.py

@@ -136,8 +136,16 @@ def test_draft_is_revisable_and_final_comes_from_decoder(self):
         self.assertEqual(snapshots.update("你好", "你好")["draft"], "")
         final = snapshots.update("你好", "你好！", terminal=True)
         self.assertEqual((final["finalized"], final["draft"]), ("你好！", ""))
-        with self.assertRaises(ValueError):
-            snapshots.update("cannot match", "different")
+        # A rewritten decode must re-commit only the agreed prefix instead of
+        # failing: audio is already captured and the terminal text wins.
+        recovered = snapshots.update("cannot match", "different")
+        self.assertEqual(recovered["finalized"], "")
+        self.assertEqual(recovered["finalized"] + recovered["draft"], "different")
+        partial = snapshots.update("我们去了Co", "我们去了科蒂纳。")
+        self.assertEqual(
+            (partial["finalized"], partial["draft"]), ("我们去了", "科蒂纳。")
+        )
+        self.assertNotEqual(snapshots.sequence, 0)
 
     def run_fake(self, finish=True, gpu_available=True):
         FakeSession.calls = []

openless-all/app/src-tauri/src/asr/local/experimental/textstream/worker.py

@@ -99,7 +99,17 @@ def update(self, finalized: str, full: str, terminal: bool = False) -> dict:
         if terminal:
             finalized = full
         if not full.startswith(finalized):
-            raise ValueError("decoder snapshot does not contain its finalized prefix")
+            # A decode may rewrite text that an earlier snapshot reported as
+            # stable (script or normalisation flips). The protocol carries whole
+            # previews, and the terminal snapshot is authoritative, so keep the
+            # authoritative text and re-commit only the prefix both agree on
+            # instead of failing the whole transcription.
+            agreed = 0
+            for previous, current in zip(finalized, full):
+                if previous != current:
+                    break
+                agreed += 1
+            finalized = finalized[:agreed]
         self.finalized, self.draft = finalized, full[len(finalized) :]
         self.sequence += 1
         return {