fix(native-chat): reject coarse-mtime rewrites

src/main/native-chat/ssh-transcript-range-fs.test.ts

@@ -93,4 +93,17 @@ describe('SSH transcript range stability', () => {
       TranscriptRangeReadInvalidatedError
     )
   })
+
+  it('rejects a same-length rewrite even when remote mtime is coarse', async () => {
+    const remote = mutableProvider('old generation')
+    mocks.provider = remote.provider
+    const rangeFs = await createSshTranscriptRangeFs('ssh-owner')
+    const openingStamp = await rangeFs.stat(TRANSCRIPT_PATH, undefined, true)
+
+    remote.replace('new generation', false)
+
+    await expect(rangeFs.assertStable(TRANSCRIPT_PATH, openingStamp)).rejects.toBeInstanceOf(
+      TranscriptRangeReadInvalidatedError
+    )
+  })
 })

src/main/native-chat/ssh-transcript-range-fs.ts

@@ -109,7 +109,9 @@ export async function createSshTranscriptRangeFs(
         if (versionChanged) {
           throw new TranscriptRangeReadInvalidatedError()
         }
-        return
+        if (openingStamp.size === 0) {
+          return
+        }
       }
       if (!openingStamp.boundaryFingerprint) {
         throw new TranscriptRangeReadInvalidatedError()