audit: NY-anchored weekend calendar (all 3 copies) + FB2_EMA_LO crash-proofing

Owner decisions from the 2026-08-04 audit report:
- spread-in-exit-triggers: DECLINED (books stay comparable; ledger in
  CLAUDE.md records the measured ~4-6% optimism).
- weekend clock: FIXED. The market week is Fri 17:00 -> Sun 18:00 New
  York time, not Fri/Sun 22:00 UTC — during US DST the Oanda feed stops
  at 21:00 UTC (measured: 159/162 summer weekends). All three weekend
  implementations (providers/base, signal_aggregator, gpu_backtest
  calendar filter) now share the NY-anchored rule; a new test sweeps
  them hourly across both DST transitions and asserts agreement. No NTP
  needed — the host clock was fine, the constant was wrong.
  Ends the weekly false-"STALE DATA / feed lagging" hours (summer Fri
  21-22 UTC, winter Sun 22-23 UTC).
- FB2_EMA_LO (delegated): kept as a research knob but crash-proofed —
  an unparseable value degrades to the tuned default 0.5 with a warning
  instead of killing every scan. Documented in CLAUDE.md.

Book gates: M15 12mo pinned book byte-identical (+78.7111R, 397
trades). M5 12mo drops exactly ONE trade (556 -> 555, +97.56 ->
+98.64R): a phantom whose signal fired on the final summer-Friday bar
(decision 21:00 UTC = NY 17:00 market close) and was "filled" at
Sunday's reopen 49 hours later, -1.08R — an entry live trading can
never take. The backtest no longer contains it; live == backtest
parity improved. M15 unaffected because hour 21 is in its blocked set.

Suite: 341/341 green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UnZkzeFcTu9agFg8BDh2tn

CLAUDE.md

@@ -74,12 +74,12 @@ Signal currency everywhere is `SignalStrength` (−2..+2). DataFrames are UTC tz
 8. Don't add config fields nothing reads; don't disable indicators in production paths (`disabled_indicators` is for experiments only).
 9. EUR/USD was removed 2026-07-16 after a no-edge verdict (cost-to-volatility; last commit with EUR support: `7d3fd95`). Do not re-add without new data. BTC/ETH work lives on unmerged branches only.
 
-## Known open items from the 2026-08-04 QA audit (owner decisions pending)
+## 2026-08-04 QA audit — owner decisions ledger
 
-- **Weekend constant vs Oanda reality**: `_is_forex_weekend` hardcodes Fri 22:00→Sun 22:00 UTC, but Oanda's week is Fri 17:00→Sun 18:00 New York time — during US DST the feed stops at 21:00 UTC (159/162 summer weekends measured) and winter reopen is Sun 23:00. Result: two false-"STALE DATA/feed lagging" hours weekly (summer Fri 21–22, winter Sun 22–23). Fix = NY-anchored calendar in all three copies; books provably unaffected (no bars exist in those hours) but run a book gate anyway.
-- **Spread in exit-trigger detection (rule 6)**: backtest stop triggers use raw mid High/Low; bid/ask-adjusted triggers would change 15/397 trades (−3.55R) at $0.30 and 30/397 (−4.24R) at $0.65 on the pinned M15 12mo book — a ~4–6% systematic optimism. Fixing invalidates all book comparability: conscious re-pin decision only.
-- **H4 seeding divergence**: live H4 fetches only 380 bars; the backtest sees unbounded history — ~2% of sampled H4 bars flip an indicator signal (composite Δ up to 12.3). M5/M15/H1 are clean at their real fetch depths. H4 is already "unproven for auto-execution".
-- `FB2_EMA_LO` env var is an undocumented knob inside the scoring path (`signal_aggregator.py` EMA200-proximity penalty floor); an unparseable value crashes every analysis. Remove or config-ify only with rule-1 revalidation.
+- **Weekend calendar: FIXED (owner-approved 2026-08-04).** All three `_is_forex_weekend` copies are NY-anchored (Fri 17:00 → Sun 18:00 ET; during US DST that is Fri 21:00 UTC — measured on 5yr of Oanda bars). Kills the weekly false-"STALE DATA/feed lagging" hours. Book impact, fully accounted: M15 byte-identical; M5 12mo dropped exactly ONE trade — a phantom whose signal fired on the final summer-Friday bar (close 21:00 UTC) and "filled" at Sunday's reopen 49 h later (−1.08R, live-impossible). M5 12mo reference at HEAD: 555 trades, +98.64R PF≈1.50 @ $0.65 (was 556/+97.56/1.48). A Module 21 test sweeps all three copies hourly across both DST transitions.
+- **Spread in exit-trigger detection (rule 6): owner DECLINED 2026-08-04.** Backtest stop triggers stay on raw mid High/Low; the measured optimism (~4–6% of total R: −3.55R @ $0.30, −4.24R @ $0.65 on the M15 12mo book) is accepted and books stay comparable. Re-open only as a conscious re-pin campaign.
+- **`FB2_EMA_LO`: HARDENED 2026-08-04 (delegated).** Research override for the EMA200-proximity band, default = tuned 0.5; an unparseable value now degrades to the default with a warning instead of crashing every scan. Documented here — it is a knob that exists.
+- **H4 seeding divergence: parked.** Live H4 fetches only 380 bars vs the backtest's unbounded history — ~2% of sampled H4 bars flip an indicator signal (composite Δ up to 12.3). M5/M15/H1 clean at their real fetch depths. Fold into any future H4 campaign; H4 remains "unproven for auto-execution".
 
 ## Current state notes (2026-07-30)