fix(daemon): preserve the write error's structured details in the close-time save failure

Review feedback on #1392 (thymikee): toOrdinaryCloseSaveScriptFailure
rebuilt the AppError from only the original message, dropping its
machine-readable details.reason ("script_target_exists"), details.path,
and cause. A caller dispatching on those fields (or reading the CLI's
--json error.details) lost them even though the underlying write
failure carried them.

Preserve the original error's details/cause, overriding only the
close-specific hint and retriable:false. Extends the #1391 regression
test to assert the routed close response still carries reason/path.

Author: thymikee

src/daemon/handlers/__tests__/session-device-claims.test.ts

@@ -299,6 +299,11 @@ test('#1391: a close-time script save failure still clears the advisory claim an
   assert.equal(error.code, 'COMMAND_FAILED');
   assert.match(error.message, /session was closed, but its script was not saved/);
   assert.equal(error.details?.retriable, false);
+  // The original write failure's machine-readable details survive the
+  // close-specific hint/retriable override, so a caller dispatching on them
+  // (e.g. `reason === 'script_target_exists'`) still can.
+  assert.equal(error.details?.reason, 'script_target_exists');
+  assert.equal(error.details?.path, targetPath);
   assert.equal(store.get('close-save-script-failure'), undefined);
   assert.deepEqual(inspectDeviceClaims({ serial: android.id }), []);
   assert.equal(fs.readFileSync(targetPath, 'utf8'), 'pre-existing\n');

src/daemon/handlers/session-close.ts

@@ -289,21 +289,33 @@ function finalizeOrdinaryCloseScript(params: {
  * here (a non-clobber refusal or another fs AppError — see
  * `handleSessionScriptWriteFailure`'s non-repair, non-active-publication
  * branch); anything else is already swallowed into a silent `{written:false}`
- * there. The message is corrected for THIS call site: the shared
- * `publishHealedScriptAtomically` wording ("retry close --save-script")
+ * there. Only the message/hint/retriable are corrected for THIS call site (the
+ * shared `publishHealedScriptAtomically` wording, "retry close --save-script",
  * describes the repair-commit retry contract, which does not apply here — by
  * the time the agent sees this, `close` has already released the device and
- * deleted the session, so there is nothing left to retry in place.
+ * deleted the session, so there is nothing left to retry in place); the
+ * original error's machine-readable `details` (e.g. `reason:
+ * "script_target_exists"`, `path`) are preserved so a caller dispatching on
+ * them still can.
  */
 function toOrdinaryCloseSaveScriptFailure(error: unknown): AppError {
-  const detail = error instanceof AppError ? error.message : normalizeError(error).message;
+  const overrides = {
+    hint: 'Remove the existing target (or pass --force/--overwrite), then re-record with open --save-script.',
+    retriable: false,
+  };
+  if (error instanceof AppError) {
+    return new AppError(
+      'COMMAND_FAILED',
+      `The session was closed, but its script was not saved: ${error.message}`,
+      { ...error.details, ...overrides },
+      error.cause,
+    );
+  }
+  const detail = normalizeError(error).message;
   return new AppError(
     'COMMAND_FAILED',
     `The session was closed, but its script was not saved: ${detail}`,
-    {
-      hint: 'Remove the existing target (or pass --force/--overwrite), then re-record with open --save-script.',
-      retriable: false,
-    },
+    overrides,
   );
 }