# CQA-2 — capture-qa reads only the latest file, so a missing today-file fails nothing and a failing stream mails under another stream's name

status: open · raised panel run 16 (2026-09-01), executing the 2026-08-31
daily-audit memo's detector hand-off (items a+b, folded by adversarial
review) · class: instrument-calibration / loudness (capture QA layer) ·
judgement: **YES** · effort ~0.25–0.4 pd · horizon: live now — the memo
predicts repeat mislabeled 🔴 mails until a full pit snapshot lands, and the
trailing-hole blindness holds for every expect-every-day stream

---

**Plain-language summary for an owner reading one paragraph.** The nightly
capture quality check only ever looks at the newest file a stream has. Two
consequences, both observed last week: when today's file is *missing
entirely*, nothing fails — the check re-reads yesterday's file, so the one
condition that means "we are losing a day right now" is invisible to the one
instrument that can red; and because the check for ALL streams runs inside
the skew-snapshot job, the failure mails arrive as "🔴 skew-snapshot capture"
even when the failing stream is pit_snapshots, owned by a different workflow
— which is exactly how the 08-28/08-29 alerts mislabeled themselves. The fix:
make "today's file is missing" a distinct failing condition naming the stream
and date, and put the failing stream names in the alert subject.

## Mechanism — verified at HEAD `29c6f23`

- `capture_qa` reads `files[-1]` per stream only
  (`src/thales/data/captures.py:810-834`). "Today's file missing" is not a
  failing condition anywhere: staleness (`capture_status`) is report-only by
  design (exit 0), and the interior-gap detector `capture_gaps` windows *"up
  to the stream's OWN latest capture (never past it — a stream that is merely
  stale is STALE, which staleness already reports)"* (its own comment,
  `captures.py:357-363`). That deliberate hand-off cedes the trailing hole to
  a channel that fails nothing — the hand-off with no failing endpoint is
  this row's defect, cited here so the row cannot be read as GAP-1
  relitigation (GAP-1's narrowed scope is the full-history census + the
  window ruling).
- The alert subject is workflow-static: `_alert.yml` builds
  `Subject: 🔴 {label} {result}` from a workflow-level env
  (`.github/workflows/_alert.yml:85`), and `skew-snapshot.yml:103` runs
  `thales capture-qa` across all registered streams — so a pit_snapshots
  failure (owned by paper-trading.yml) is structurally guaranteed to mail as
  a skew failure. Per-stream ❌ lines exist only in the Actions log.

**Struck by adversarial review, recorded so it stays struck:** the memo's
complaint that the same degraded file "re-fires nightly with no new
information" is NOT part of this row. A standing red until fixed is correct
fail-closed behavior, and the tempting remedy — an acknowledged-degradation
ledger — would be a second ACK surface and a mechanism for making reds
quiet, the opposite of this shop's doctrine. The observed harm was
misattribution, not repetition.

## Fix shape (propose-only)

1. **Missing-today check**: for streams registered as expect-every-trading-day,
   a trading day with no file (after the stream's normal publication lag —
   pit is legitimately T-1) is a distinct `capture_qa` failure naming the
   stream and the missing date.
2. **Subject attribution**: `capture-qa` emits the failing stream names
   (e.g. to a step output/file) and the alert includes them in the subject —
   "🔴 capture-qa: pit_snapshots" instead of the owning workflow's static
   label.

## Test design + kill criterion (pre-registered, negative-controlled)

- Fixture with today's file absent on a trading day → a distinct "missing"
  failure naming stream + date; revert → red.
- **Lag negative control (required):** a stream at T-1 within its normal
  registered publication lag must NOT red — without this the check
  manufactures a nightly false positive by construction, the alert-fatigue
  class this shop keeps paying for.
- Subject fixture: a forced pit_snapshots QA failure inside the skew job
  produces an alert whose subject names pit_snapshots; revert the wiring →
  only its test reds.
- **Falsifier:** if the missing-today check produces ≥1 false red on a
  legitimate holiday/lag day within 20 shadow trading days, the lag model is
  wrong — record and re-derive per-stream lags from the stream's own
  history; do not whitelist dates ad hoc.

## Data plan

None — owned state and static code; rides the existing capture-qa cron.

## Cap note

Ranked second of this run's two rows (PIT-1 first: it stops permanent data
loss; this row stops misattribution and blindness, nothing is destroyed). If
the 12-cap must hold hard after SKW-1's open→built move lands, this is the
row to hold at the gate.