fix(sec): alert when a filing gap's reprieve lapses instead of re-pausing quietly

An escalated gap stops pausing setups while the issuer's own fundamentals are
still recent. That reprieve ends on its own — the stored filings age past
GAP_GATE_RECENT_FILING_DAYS, or a newer gap arrives and the all-escalated
condition fails — and nothing reported either, because filing_gap_aged only
escalates gaps whose escalated_at is NULL and so never fires twice for the same
gap. For the 43 issuers behind the previous commit that lands around
2026-10-26, when their late-April filings age out together.

sec_filing_gaps.exempted_at (migration 034) makes the transition observable:
stamped quietly while the issuer is exempt, cleared when the exemption lapses,
and the clear is what raises filing_gap_repaused — once per lapse, re-arming if
the issuer's data recovers and ages out again. A gap that was never exempt has
no transition and stays silent; it is simply still paused, which
filing_gap_aged already said.

gap_exempt_ciks is public so the importer alerts on membership changes in
exactly the set the gate reads, rather than restating the rule.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016Lo99z3jWqu9X9ueBU3Z3D

tests/unit/test_sec_fundamentals_importer.py

@@ -1388,3 +1388,79 @@ async def test_reparse_never_restamps_a_collision_onto_the_co_registrant(engine)
     async with factory() as s:
         row = (await s.execute(select(FundamentalSnapshot))).scalar_one()
     assert row.cik == "0000906107"  # still the issuer that filed it
+
+
+# --- the reprieve ending: an exemption that lapses must not do so silently ---
+
+def _stale_gap(cik, *, exempted: bool):
+    now = datetime.now(timezone.utc)
+    return SecFilingGap(
+        cik=cik, accession=f"{cik}-AGED-Q", form="10-Q",
+        index_date=(now - timedelta(days=30)).date(), reason="not_in_companyfacts",
+        first_seen_at=now - timedelta(days=30), last_attempted_at=now,
+        escalated_at=now - timedelta(days=16),
+        exempted_at=(now - timedelta(days=16)) if exempted else None,
+    )
+
+
+def _snapshot(cik, *, age_days):
+    filed = date.today() - timedelta(days=age_days)
+    return FundamentalSnapshot(
+        cik=cik, accession=f"{cik}-PRIOR", form="10-Q", filed_date=filed,
+        accepted_at=datetime.now(timezone.utc) - timedelta(days=age_days),
+        period_end=filed, fiscal_year=filed.year, fiscal_period="Q1",
+    )
+
+
+async def _promote_only(engine, seed):
+    """Run promote() alone against seeded gap/snapshot state."""
+    factory = _factory(engine)
+    async with factory() as s:
+        for obj in seed:
+            s.add(obj)
+        await s.commit()
+    importer = _importer(FakeSecClient(
+        tickers={}, companyfacts={}, submissions={}, latest_index=date(2026, 3, 1)
+    ))
+    async with factory() as db:
+        await importer.promote(db, StagedFundamentals(resolved=ResolvedUniverse()), run_id=77)
+        await db.commit()
+    async with factory() as s:
+        gaps = (await s.execute(select(SecFilingGap))).scalars().all()
+        events = (await s.execute(select(SystemEvent))).scalars().all()
+    return gaps, events
+
+
+async def test_a_lapsed_exemption_raises_its_own_alert(engine):
+    """filing_gap_aged fires once and never again, so nothing else would say the
+    pause came back when the issuer's own fundamentals aged out."""
+    cik = "0000000060"
+    gaps, events = await _promote_only(
+        engine, [_stale_gap(cik, exempted=True), _snapshot(cik, age_days=400)]
+    )
+    repaused = [e for e in events if e.code == "filing_gap_repaused"]
+    assert len(repaused) == 1
+    assert f"{cik}/{cik}-AGED-Q" in repaused[0].message
+    # Cleared, so a later recovery can re-arm and lapse again.
+    assert gaps[0].exempted_at is None
+
+
+async def test_an_exemption_taking_effect_is_stamped_silently(engine):
+    """Setups resuming is what filing_gap_aged already described — stamping the
+    state must not raise a second alert for it."""
+    cik = "0000000061"
+    gaps, events = await _promote_only(
+        engine, [_stale_gap(cik, exempted=False), _snapshot(cik, age_days=120)]
+    )
+    assert [e.code for e in events if e.code.startswith("filing_gap")] == []
+    assert gaps[0].exempted_at is not None
+
+
+async def test_a_still_paused_gap_is_not_reported_as_lapsing(engine):
+    """It never became exempt, so there is no transition to report."""
+    cik = "0000000062"
+    gaps, events = await _promote_only(
+        engine, [_stale_gap(cik, exempted=False), _snapshot(cik, age_days=400)]
+    )
+    assert [e for e in events if e.code == "filing_gap_repaused"] == []
+    assert gaps[0].exempted_at is None