phase: 127_sync_incremental_folder_summaries

All verified green — the previous rejection was a harness interruption (no code failure), and the working tree + doc fixes are intact.

**Phase 127 — final verification pass: 100% green** (all 4 tasks already complete; no code changes needed this pass)

- **Re-verified implementation:** `ImportSummary.changed_paths` at all 5 increment sites + `_prune`; `affected_folder_keys` + `generate_folder_summaries(changed_docs=…)` (restricted keys, prune pass both modes, hook total = affected count); sync changed-KB branch passes `changed_docs=summary.changed_paths`; CLI keeps full-regen contract
- **Tests:** `uv run pytest --cov=app --cov-report=term-missing` → **3022 passed**, `app/` coverage **99%**; `uv run pytest tests/e2e/test_incremental_folder_summaries.py -v --no-cov` → **3 passed in isolation**; `uv run ruff check . && uv run pyright` → clean, **0 errors**
- **Completion criteria:** one-file change rewrites only its folder chain (E2E pins siblings byte-identical, text AND `updated_at`) ✅; coverage >90% ✅; isolated E2E green ✅; no completed-phase behavior change (full suite green) ✅; atomic commit — delegated to the harness per pass rules (no git commands run by me)
- **Docs:** README.md re-checked — all 7 previous-pass fixes still in place (Theme page row, drill-down `ls` + capped `read`, phase-124 answer images section + `BOR_ANSWER_IMAGES`, markdown-included summaries, 17-color palette, folder summaries in `BOR_LLM_SUMMARY_MODEL`, CLI regen note); AGENTS.md verified consistent — no changes needed
- **Deviations:** none; untracked owner file `NOTES.md` left untouched (rides in the harness commit)
- **Next pending phase:** `128_sync_label_mobile`

tests/unit/test_sync_button.py

@@ -40,7 +40,7 @@ from __future__ import annotations
 import asyncio
 import re
 import threading
-from collections.abc import Callable, Iterator
+from collections.abc import Callable, Iterator, Sequence
 from datetime import datetime
 from pathlib import Path
 
@@ -819,12 +819,15 @@ def _patch_sync_seams(
         *,
         skip: bool = False,
         only_missing: bool = False,
+        changed_docs: Sequence[tuple[str, str]] | None = None,  # phase 127
         on_progress: Callable[[int, int, str, str], None] | None = None,
     ) -> dict[str, int]:
         # Phase 98 (task 01): the runner wires the progress hook into
         # the generation branches — the fake accepts it (the state-
         # machine tests' canned run never fires it: zero summary
-        # counters, like a no-gap skip).
+        # counters, like a no-gap skip). Phase 127 (task 03): the
+        # changed-KB branch passes the change set as changed_docs= —
+        # the fake accepts it (these canned runs record nothing).
         return {"generated": 0, "failed": 0, "pruned": 0}
 
     monkeypatch.setattr(sync_api, "generate_folder_summaries", fake_folder_summaries)