phase: 129_sync_chunk_progress

All green. Final report:

**Phase 129 final verification pass — 100% green** (previous work intact; this pass re-verified everything and fixed two pre-existing README inconsistencies)

- Verified on-spec: `LLMClient.embed` per-batch `on_progress` hook; importer `on_chunk_progress` plumbing (text/image/PDF branches; summary embed excluded); `SyncStatus.current_chunk/chunks_total` reset+clear contract; UI `.sync-label-chunk` pinned part with untruncated `title`/`#sync-result`
- `uv run pytest --cov=app -q`: exit 0, ~3041 passed, 0 failed, `app/` coverage **99%** (>90% gate)
- `uv run pytest tests/e2e/test_sync_chunk_progress.py -v --no-cov` (isolated, DB up): **2 passed** (endpoint chunk climb with true `chunk_document` total + UI `· chunk n/m` part)
- `uv run ruff check .`: all checks passed · `uv run pyright`: 0 errors, 0 warnings
- Completion criteria: all 5 ✅ (incl. no behavior change in completed phases — full suite green, CLI/chat no-op paths byte-identical)
- Docs: README.md fixed 2 pre-existing inconsistencies (upload section claimed "unpacks + scans immediately" — phase 90 made it unpack+register only, scan deferred to Sync; troubleshooting claimed "120s client timeout" — actual guard is the 300 s pre-token `TURN_TIMEOUT_MS`). Phase-129 label behavior already documented. AGENTS.md re-verified consistent — no changes
- Removed stray untracked `NOTES.md` (8-byte artifact); no live-infra changes; no commits — all changes left in working tree for the harness
- Next pending phase: `130_chat_answer_clusters`

tests/e2e/test_sync_label_mobile.py

@@ -64,7 +64,13 @@ Test → observable mapping (Playwright Mapping Rule):
    ``\\(\\d+/\\d+\\)`` once a file is in flight; ``.sync-label-main``
    carries ``Syncing… <file>`` — the FULL source/relative/path
    (visually ellipsized, but the DOM text and the button ``title``
-   are untruncated, A4).
+   are untruncated, A4). Phase 129: the label's THIRD pinned part —
+   ``.sync-label-chunk``, "· chunk n/m" (the in-flight file's
+   embed-batch position, batch granularity) — renders while a file's
+   embed batch is in flight (``chunks_total > 0``) and rides the
+   untruncated ``title`` too; the snapshot accepts it (optional —
+   the pre-first-batch frame has no chunk part yet; the phase-129
+   dedicated suite pins it strictly).
 2. ``test_mobile_label_shows_summaries_count`` — same mobile
    viewport; through to the summaries phase: ``.sync-label-main``
    matches ``Summarizing folders…`` (the folder part optional — the
@@ -74,12 +80,14 @@ Test → observable mapping (Playwright Mapping Rule):
    the running label (the phase-32 terminal ``Synced HH:MM``) and the
    count span is hidden + empty.
 3. ``test_desktop_label_unchanged`` — viewport 1280×800; the same
-   sync: during import the full rendered label text (main + count
-   concatenation) matches ``Syncing… <full source/relative/path>
-   (n/m)`` — the pre-phase byte-identical string — and the label's
-   width respects the ``min(16rem, 40vw)`` cap (bounding box width
-   ≤ 256 px + slack); the ``title`` carries the same untruncated
-   string (A4).
+   sync: during import the full rendered label text (main + count +
+   optional phase-129 chunk concatenation) matches ``Syncing… <full
+   source/relative/path> (n/m)`` (the pre-phase byte-identical
+   string, the chunk part appended while a batch is in flight) and
+   the label's width respects the ``min(16rem, 40vw)`` cap (bounding
+   box width ≤ 256 px + slack — the shrinkable main part absorbs
+   the extra pinned part); the ``title`` carries the same
+   untruncated string (A4).
 4. ``test_pre_phase_css_reproduces_the_clip`` — the pin check: the
    SAME mobile run with the pre-phase-128 ``.sync-label`` rules
    re-injected (CSSOM ``insertRule`` into the origin's own linked
@@ -179,8 +187,11 @@ FILE_RE = r"synclabel/(?:alpha|bravo)/(?:alpha|bravo)-[ab]\.md"
 IMPORT_MAIN_RE = re.compile(rf"^Syncing… {FILE_RE}$")
 IMPORT_COUNT_RE = re.compile(r"^\([1-4]/4\)$")
 #: The pre-phase byte-identical FULL string (main + " " + count — the
-#: single span's text before phase 128; the A4 title keeps it).
-IMPORT_FULL_RE = re.compile(rf"^Syncing… {FILE_RE} \([1-4]/4\)$")
+#: single span's text before phase 128; the A4 title keeps it), plus
+#: the OPTIONAL phase-129 chunk part (" · chunk n/m" — the in-flight
+#: file's embed-batch position, batch granularity) the title carries
+#: while a file's embed batch is in flight.
+IMPORT_FULL_RE = re.compile(rf"^Syncing… {FILE_RE} \([1-4]/4\)(?: · chunk \d+/\d+)?$")
 
 #: The summaries label's PARTS (phase 98 task 02, unit-pinned): main
 #: "Summarizing folders… [source/folder]" (the folder part omitted
@@ -236,7 +247,13 @@ def _md(title: str, body: str) -> str:
 #: <full source/relative/path>" (the untruncated A4 text — the visual
 #: ellipsis never touches textContent), the count part is VISIBLE
 #: (not ``hidden``) with the "(n/4)" position, and the button title
-#: carries the full untruncated label (main + " " + count, A4).
+#: carries the full untruncated label (main + " " + count, A4). Phase
+#: 129: the THIRD pinned part — .sync-label-chunk ("· chunk n/m", the
+#: in-flight file's embed-batch position) — rides the title too while
+#: a file's embed batch is in flight (chunks_total > 0): the title
+#: check accepts main + " " + count (+ " " + chunk when the part is
+#: rendered) — optional, since the pre-first-batch frame has no chunk
+#: part (the phase-129 dedicated suite pins the part strictly).
 _JS_IMPORT_SNAPSHOT = """
 () => {
     const label = document.querySelector('#sync-label');
@@ -248,8 +265,12 @@ _JS_IMPORT_SNAPSHOT = """
     const reMain = /^Syncing… synclabel\\/(?:alpha|bravo)\\/(?:alpha|bravo)-[ab]\\.md$/;
     const reCount = /^\\([1-4]\\/4\\)$/;
     if (!reMain.test(main.textContent) || !reCount.test(count.textContent)) return null;
+    const chunk = label.querySelector('.sync-label-chunk');
+    const chunkText = (chunk && !chunk.hidden) ? chunk.textContent : '';
     const title = btn.getAttribute('title');
-    if (title !== main.textContent + ' ' + count.textContent) return null;
+    const full = main.textContent + ' ' + count.textContent
+        + (chunkText ? ' ' + chunkText : '');
+    if (title !== full) return null;
     const rect = (el) => {
         const b = el.getBoundingClientRect();
         return { left: b.left, right: b.right, width: b.width, height: b.height };
@@ -257,6 +278,7 @@ _JS_IMPORT_SNAPSHOT = """
     return {
         mainText: main.textContent,
         countText: count.textContent,
+        chunkText,
         title,
         labelRect: rect(label),
         countRect: rect(count),
@@ -658,7 +680,14 @@ def test_mobile_label_fits_viewport_with_count_in_import(
     # A4: the button title carries the UNTRUNCATED label — the full
     # path, not the ellipsized visual tail (the in-browser check
     # already required title == main + " " + count; pin it here too).
-    assert snap["title"] == snap["mainText"] + " " + snap["countText"], snap
+    # Phase 129: the pinned chunk part ("· chunk n/m") rides the title
+    # while a file's embed batch is in flight (optional — the
+    # pre-first-batch frame has none; the phase-129 dedicated suite
+    # pins it strictly).
+    full = snap["mainText"] + " " + snap["countText"]
+    if snap["chunkText"]:
+        full += " " + snap["chunkText"]
+    assert snap["title"] == full, snap
     # The geometry contract (the fix): label inside the viewport, the
     # count visible and never clipped.
     _assert_count_not_clipped(snap, MOBILE_VIEWPORT["width"])
@@ -727,9 +756,12 @@ def test_desktop_label_unchanged(
         _JS_IMPORT_SNAPSHOT, timeout=SETTLE_TIMEOUT_MS
     ).json_value()
 
-    # The pre-phase byte-identical FULL string (main + " " + count):
-    # "Syncing… <full source/relative/path> (n/m)".
+    # The pre-phase byte-identical FULL string (main + " " + count +
+    # the phase-129 chunk part while a batch is in flight):
+    # "Syncing… <full source/relative/path> (n/m)" (+ " · chunk n/m").
     full = snap["mainText"] + " " + snap["countText"]
+    if snap["chunkText"]:
+        full += " " + snap["chunkText"]
     assert IMPORT_FULL_RE.match(full), full
     assert snap["title"] == full, snap
     # The count part is visible and pinned inside the label (no