fix(daemon): keep stripping title markers in the post-close remainder of one delta

mrcfps's non-blocking thread on #6342 round-2 review (apps/daemon/src/title-marker.ts L97,
2026-08-02) noted that the previous implementation did

  emitTitle(buffer.slice(titleStart, closeIndex));
  buffer = buffer.slice(closeIndex + TITLE_CLOSE_TAG.length);
  visible += buffer;
  buffer = '';

right after the first close tag, which forwarded the post-close remainder to
`visible` without scanning it. Stream delta boundaries are transport-dependent,
so identical model output could leak a raw `<od-title>Two</od-title>` depending
on adapter chunking — breaking the "scanner remains active" invariant this PR
introduced in the comment two lines above.

Concretely, one call with `<od-title>One</od-title>A<od-title>Two</od-title>B`
returned `A<od-title>Two</od-title>B`, whereas splitting the same bytes into
two `strip()` calls removed both markers.

Fix: drop the `visible += buffer; buffer = '';` flush and `continue` the
while loop instead, so the post-close remainder re-enters the same
single-marker scanner. Multiple markers in one delta are now stripped in
the same pass; `emitted` still de-dupes title events across the run.

Test: `apps/daemon/tests/title-marker.test.ts` gains a regression
`title marker stripper strips every marker inside one delta (post-close
remainder keeps scanning)` that asserts `<od-title>One</od-title>A<od-title>Two</od-title>B`
returns `AB` and only `One` is emitted as a title; no marker remains in
the visible output or in the post-flush leftover.

7/7 tests pass locally:
  pnpm --filter @open-design/daemon exec vitest run tests/title-marker.test.ts

Signed-off-by: xxiaoxiong <2482929840@qq.com>

Author: xxiaoxiong

apps/daemon/src/title-marker.ts

@@ -94,11 +94,12 @@ export function createAgentTitleMarkerStripper(
 
       emitTitle(buffer.slice(titleStart, closeIndex));
       buffer = buffer.slice(closeIndex + TITLE_CLOSE_TAG.length);
-      // Keep scanning so subsequent markers in the same run are also
-      // stripped. `emitted` prevents duplicate title events within
-      // this stripper instance.
-      visible += buffer;
-      buffer = '';
+      // Keep scanning so subsequent markers in the same run are
+      // also stripped. `emitted` prevents duplicate title events
+      // within this stripper instance. The while loop continues
+      // with the remaining buffer, so a second marker in the same
+      // delta is handled without leaking the raw tag through.
+      continue;
     }
 
     return visible;

apps/daemon/tests/title-marker.test.ts

@@ -94,3 +94,29 @@ test('title marker stripper strips across per-run instances when shouldEmitTitle
     '\n\nMore');
   assert.deepEqual(turn2.titles, []);
 });
+
+test('title marker stripper strips every marker inside one delta (post-close remainder keeps scanning)', () => {
+  // Regression for the mrcfps non-blocking thread on #6342 round-2 review
+  // (2026-08-02): the prior implementation did
+  //   `visible += buffer; buffer = '';`
+  // immediately after the first close tag, which forwarded the post-close
+  // remainder without scanning it. Stream delta boundaries are
+  // transport-dependent, so identical model output could leak a raw
+  // `<od-title>Two</od-title>` depending on adapter chunking — breaking
+  // the "scanner remains active" invariant this PR introduced.
+  //
+  // After the fix, the stripper keeps the post-close remainder in `buffer`
+  // and continues the loop instead of flushing visible text and clearing,
+  // so multiple markers in one delta are all stripped in the same pass.
+  const { stripper, titles } = createStripper();
+
+  assert.equal(
+    stripper.strip('<od-title>One</od-title>A<od-title>Two</od-title>B'),
+    'AB',
+  );
+  // `emitted` only de-dupes title events from a single stripper instance;
+  // the first marker wins, and the second is silently stripped without
+  // firing a duplicate title (mirrors the multi-turn behavior above).
+  assert.deepEqual(titles, ['One']);
+  assert.equal(stripper.flush(), '');
+});