docs: record real dated dividend collector session (2026-08-27)

docs/engineering-log.md

@@ -103,3 +103,4 @@
 - PIT siamchart vintage store (2026-08-27, commit `887e9c9`): added `siamchart_vintages.py` (append-only hash-chained store of every collected siamchart snapshot; `snapshot_at(as_of)` returns the newest snapshot with `retrieved_at <= as_of` — anti-look-ahead, fail-closed). `PitScoreProvider` accepts `siamchart_store`; when wired the fundamental dimension reads the snapshot knowable at as_of (`pit_grade='pit'`) and `partial_pit` no longer forces true. `/api/v1/backtest use_pit` seeds the first vintage from the current snapshot. Full backend **273 passed** (was 266). Honest scope: snapshot reconstruction forward only; EPS year-keys not tied to calendar years (growth = latest-vs-prior).
 - Real forward-test lifecycle (2026-08-27, commits `6d9c283` + `80c6d79`): the cosmetic "forward" (same single-pass backtest, different mode string) is replaced with a durable, frozen-signal paper-portfolio lifecycle. `forward_test.py` `ForwardTestStore` (thread-safe JSON store) with status flow: frozen (signals snapshotted immutable) → executed (fills 50/20/30 at post-freeze prices) → marked (mark-to-market equity series) → matured (net_return). New routes: `GET /api/v1/forward(+<id>)`, `POST /api/v1/forward` (create+execute, `use_pit` freeze), `POST /<id>/mark`, `POST /<id>/mature`; store at `data/forward/runs.json` (survives restarts). UI simulation tab: forward calls `/api/v1/forward`, loads runs, shows status/non-PIT/holdings + Mark/Mature per run. Full backend **280 passed** (was 273). Honest scope: score source at CREATE may be current board (`non_pit=true` tagged); paper-only.
 - Factor-learning validation gate (2026-08-27, commit `ae814c3`): closed the P4 "no auto-apply" loop — `weight_learning.py` now splits a chronological IC series into train + holdout via `apply_validation_gate`, and a factor is `validated=True` only when total sample >= 12, each window >= its min, train & holdout IC both beat baseline (BASELINE_IC=0) and agree in sign, and pooled |t| > 1.0. `apply_weight_update` keeps the weight unchanged for any unvalidated factor (no auto-apply); only validated factors move. `learn_momentum_gated` wired into `/api/v1/learning/momentum`, surfacing `ic_train`/`ic_holdout`/`validated`/`gate_notes`. Full backend **286 passed** (was 280). Live probe: momentum validated=false, gate_note "IC not above baseline (0.0711/-0.1143)" — weight unchanged.
+- Real dated dividend-history collector (2026-08-27, commit `f9973e8`): `siamchart.py` gained `parse_dividend_history`/`fetch_dividend_history` (reads the "ประวัติการปันผล" ex-date + DPS table per stock-info page); `dividend_ledger.py` gained `populate_dated_dividends` (registers dated rows, estimate=False). `POST /api/v1/dividends/update` fetches all snapshot symbols and persists a dated ledger at `data/dividends/ledger.json`; `use_ledger` backtests prefer the dated ledger (`dividend_method=dated_ledger`) and fall back to DPS estimates when unpopulated. Full backend **292 passed** (was 286). Live network fetch: 49/49 symbols, 1410 dated payments; use_ledger → `dated_ledger`. Note: this sandbox HAS outbound network (curl/https to siamchart 200) — contrary to earlier assumption.