docs(capabilities): register ibis-sqlite TimestampBucket gap in KNOWN_GAPS (item 99) - #293
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…_GAPS (item 99)
item 74's redirect of the MA truncate/round_dt/ceil_dt/floor_dt wrappers
through round_temporal/round_calendar surfaced a pre-existing gap: ibis-sqlite
has no TimestampBucket compilation rule, so a multi-digit duration string
(e.g. dt.truncate("2d")) raises a raw native OperationNotDefinedError instead
of the closed-by-default contract's BackendCapabilityError.
Not fixable with a real CapabilityFact yet -- ibis-sqlite isn't one of the 4
argument-type matrix fixtures, so a DURATION_MULTIPLIER-class fact for it
would be unexercised/untested (same structural limit as item 75/79's
ibis-polars gap, tracked via _MATRIX_UNREACHABLE_DIALECT_FACTS).
Registers the production KNOWN_GAPS entry (gaps.py) this disclosure
mechanism exists for, so it's visible in the generated coverage doc, not
just a source comment. Regenerated docs/reference/expression-coverage.{md,json}.
Full fix tracked as mountainash-central backlog item 99.
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Aug 18, 2026
…-11) (#299) Root cause (PR #297 CI investigation): DuckDB gives no row-order guarantee for ASOF JOIN output absent an explicit ORDER BY. Ibis's join_asof backend (relsys_ib_ext_ma_util.py) never applied one, so test_asof_backward_strategy[ibis-duckdb] flipped strict-xfail/XPASS ~50/50 across independent runs (confirmed via 8 isolated process reruns pre/post fix). Values were always correct; only row order backing the test's positional assertions flapped. Same incident class as backlog item 101 (PR #293, 2026-08-16, flagged but not fixed then). Fix: order the join_asof result by the join key(s) before returning, matching polars/narwhals' left-order preservation for asof joins. Deterministic across 8/8 verification runs post-fix. IB-REL-11 split: ibis-duckdb portion closed resolved_in_mountainash; distinct, still-genuine ibis-sqlite raise (no ASOF JOIN translation) carved out to new IB-REL-13. Updated divergences.py, upstream-issues.yaml, known-divergences.md, and the test's xfail marker in lockstep; regenerated expression-coverage.{md,json} and _spine_expectation_census.md. AGENTS.md: removed the stale 'local Ibis fork' dependency note — CI/dev both resolve ibis-framework from PyPI, no path dependency exists. Backlog: filed mountainash-central item 108 for a distinct, unrelated latent bug found in the same function (join_asof silently drops the strategy= parameter on Ibis — forward/nearest behave as backward) and closed item 101's flagged sub-issue.
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Summary
Registers a production
KNOWN_GAPSentry disclosing a real gap surfaced by item 74's redirect (PR #292):ibis-sqlitehas noTimestampBucketcompilation rule, soround_temporal/round_calendar(and the MA wrappers now redirecting through them) with a multi-digitmultipleonibis-sqliteraise a raw nativeOperationNotDefinedErrorinstead of a cleanBackendCapabilityError.Why not a real CapabilityFact
ibis-sqliteisn't one of the 4 argument-type matrix fixtures (polars,ibis[duckdb],narwhals-polars,narwhals-pandas), so aDURATION_MULTIPLIER-class fact for it would be unexercised/untested — same structural limit as item 75/79'sibis-polarsgap (_MATRIX_UNREACHABLE_DIALECT_FACTS). The full fix (extend the unreachable-dialect mechanism, register the real fact) is tracked as mountainash-central backlog item 99.Changes
src/mountainash/core/capabilities/gaps.py:KNOWN_GAPSnow has one real entry (was ships-empty).docs/reference/expression-coverage.{md,json}.Verification
tests/core/test_expression_coverage_model.py+tests/core/test_capability_protocol_guard.py: 39 passed.ruff check: clean.