phase: 106_document_dates

Everything is verified green. Final report:

**Phase 106 — Document dates (final verification pass; all 10 tasks already complete)**

- Verified all phase artifacts: alembic `0020` (dev DB at `0020`), `doc_dates.py`, git `file_commit_dates`, importer `doc_dates_by_root`/`dates_updated`, both entry-point wirings, date APIs + tree `created_at`/`updated_at`, LLM surfaces (prompt block, `read` line 2, appended `ls` field), `apply_recency_boost` in `retrieve()`, UI columns/badge, admin editor, mock-LLM regex — all present and correct; no defects found, no fixes needed.
- `uv run pytest --cov=app --cov-report=term-missing` → **2299 passed, TOTAL 99%** (>90% ✓)
- `uv run pytest tests/e2e/test_document_dates.py -v --no-cov` → **6/6 passed** in isolation (DB up)
- 12 regression E2E suites (retrieval_quality, whole_document_context, agent_document_tools, ls_tree_drilldown, read_truncation_cap, kb_tree, kb_tree_nav, document_viewer, edit_summaries, import_documents, sync_button, hidden_folders_toggle, smoke) → **all green in isolation**
- `uv run ruff check .` → clean; `uv run pyright` → **0 errors, 0 warnings**

**Completion criteria:** 1) non-null `created_at` + 0020 upgrade/downgrade on dev DB ✓ (real-Alembic integration tests) 2) sync refresh/older/manual-persists/content-reset/no sources_meta bump ✓ 3) zip/tar mtime + future→today ✓ 4) LLM date surfaces + cross-check ✓ 5) UI Created/Updated/badge positions ✓ 6) admin editor set+revert round-trip ✓ 7) old-correct-beats-new-similar (defaults & boost-off) + near-tie + `BOR_RECENCY_BOOST=0` byte-identical ✓ 8) full gate ✓ 9) commit/phase-move — left to harness per instructions.

- **Notable:** recency default tuned 0.001 → **0.0007** (task 07 step 5 explicitly permits; measured margins recorded in `test_recency_boost.py` docstring).
- **Next pending phase:** none — `todo/` holds only this phase.

tests/unit/test_document_viewer.py

@@ -181,6 +181,7 @@ def test_content_known_pair_maps_to_doc_content() -> None:
         content_hash="f" * 64,
     )
     doc.indexed_at = datetime(2026, 8, 22, 1, 2, 3, tzinfo=UTC)
+    doc.created_at = datetime(2026, 8, 20, 9, 0, 0, tzinfo=UTC)  # phase 106
     with _client_with_row((doc, 3)) as client:
         r = client.get(
             "/api/documents/content",
@@ -188,8 +189,11 @@ def test_content_known_pair_maps_to_doc_content() -> None:
         )
     assert r.status_code == 200
     body = r.json()
+    # Wire-additive (phase 106, task 05): the pre-date keys are all
+    # still there, joined by ``created_at``.
     assert set(body) == {
-        "source", "path", "title", "format", "summary", "content", "indexed_at", "chunks"
+        "source", "path", "title", "format", "summary", "created_at",
+        "content", "indexed_at", "chunks",
     }
     assert body["source"] == "Homelab"
     assert body["path"] == "notes/deep mark.md"
@@ -197,6 +201,7 @@ def test_content_known_pair_maps_to_doc_content() -> None:
     assert body["format"] == "md"
     assert body["summary"] is None  # markdown doc → no summary (phase 36)
     assert body["content"] == "# Deep Mark\n\nbody"
+    assert body["created_at"] == "2026-08-20T09:00:00+00:00"  # phase 106
     assert body["indexed_at"] == "2026-08-22T01:02:03+00:00"
     assert body["chunks"] == 3