mountainash-io · discreteds · Aug 18, 2026 · Aug 18, 2026
@@ -195,13 +195,7 @@ For detailed file organisation see principle: `f.development-practices/file-orga
 
 ## Dependencies
 
-**IMPORTANT:** Using **local Ibis fork** with Polars calendar interval fix:
-
-```toml
-ibis-framework = { path = "/home/nathanielramm/git/ibis", extras = ["pandas", "sqlite", "duckdb"] }
-```
-
-All other dependencies are in `pyproject.toml`.
+All dependencies are declared in `pyproject.toml` (`ibis-framework>=9.0.0` resolved from PyPI for the `ibis` extra — no local fork or path dependency).
 
 **Workspace dependency for DataPackage I/O:** `mountainash-utils-files` (sibling package, optional `storage` extra) provides `StorageFacade` used by `core/io.py` to load remote `DataResource` paths. `core.io.is_remote()` delegates to the facade's scheme registry for auto-detection; `core.io.facade_read_bytes()` calls `StorageFacade.from_path()`. Local paths bypass the facade and use Polars directly. The import is lazy so a local-only test run never touches `mountainash_utils_files`.
 

@@ -120,8 +120,9 @@ Total divergences tracked: **125**
 | IB-REL-08 | Ibis backend rename mapping inverted — expects {new: old} not {old: new} | ibis-duckdb, ibis-polars, ibis-sqlite | mountainash_internal | Strict xfail | Investigating |
 | IB-REL-09 | Ibis backend passes unsupported suffixes kwarg to Table.join() | ibis-duckdb, ibis-polars, ibis-sqlite | mountainash_internal | Strict xfail | Investigating |
 | IB-REL-10 | ibis-sqlite: drop_nans/unpivot/melt raise OperationNotDefinedError | ibis-sqlite | upstream_feature_gap | Strict xfail | Needs Filing |
-| IB-REL-11 | asof join is unreliable on Ibis SQL backends | ibis-duckdb, ibis-sqlite | upstream_bug | Strict xfail | Investigating |
+| IB-REL-11 | RESOLVED: ibis-duckdb asof join returned nondeterministic row order | ibis-duckdb | mountainash_internal | None | Resolved (internal) |
 | IB-REL-12 | cross_join between two same-named tables from different Ibis connections raises a column-binding error on SQL backends | ibis-duckdb, ibis-sqlite | mountainash_internal | Strict xfail | Investigating |
+| IB-REL-13 | ibis-sqlite: asof join raises UnsupportedOperationError | ibis-sqlite | upstream_feature_gap | Strict xfail | Needs Filing |
 
 ### Aggregate Operations
 
@@ -1263,18 +1264,18 @@ Total divergences tracked: **125**
 | Notes | ibis-sqlite lacks array/pivot relational translations: Relation.drop_nans()/ unpivot()/melt() raise OperationNotDefinedError; ibis-duckdb/ibis-polars and polars/narwhals compute them. Renamed from a colliding DivergenceFact id (was "IB-REL-07", which already named an unrelated entry above — the ArrayValue.sort() descending-parameter gap) when backlog item 87's id-collision detector caught the reuse; the DivergenceFact and this entry now self-reference via upstream_ref (backlog item 87, 2026-08-13). |
 | Last Verified | 2026-08-13 |
 
-### IB-REL-11: asof join is unreliable on Ibis SQL backends
+### IB-REL-11: RESOLVED — ibis-duckdb asof join returned nondeterministic row order
 
 | Field | Value |
 |---|---|
 | Project | ibis |
 | Category | Relational Operations |
-| Root Cause | upstream_bug |
-| Affected Backends | ibis-duckdb, ibis-sqlite |
-| Status | Investigating |
-| Workaround | Strict xfail |
-| Notes | Relation.join_asof() returns a diverging (wrong) result on ibis-duckdb and raises UnsupportedOperationError on ibis-sqlite; polars/narwhals compute it correctly. Renamed from a colliding DivergenceFact id (was "IB-REL-08", which already named an unrelated entry above — the backend rename-mapping-inverted gap) when backlog item 87's id-collision detector caught the reuse; the DivergenceFact and this entry now self-reference via upstream_ref (backlog item 87, 2026-08-13). |
-| Last Verified | 2026-08-13 |
+| Root Cause | mountainash_internal |
+| Affected Backends | ibis-duckdb |
+| Status | Resolved (internal) |
+| Workaround | None |
+| Notes | Originally described as "asof join is unreliable on Ibis SQL backends" covering both ibis-duckdb and ibis-sqlite. Root-caused 2026-08-18 (PR #297 CI investigation, repeated single-test process runs flipped xfail/XPASS ~50/50): Relation.join_asof() on the Ibis backend never applied an explicit ORDER BY, and DuckDB gives no row-order guarantee for ASOF JOIN output absent one — the query planner nondeterministically returned rows in original or shuffled order run-to-run. This was not a value divergence: join values were always correct, only the row order backing the test's positional assertions flapped. Fixed by ordering the Ibis join_asof result by the join key(s) (relsys_ib_ext_ma_util.py) to match polars/narwhals' left-order preservation. The distinct ibis-sqlite raise (no ASOF JOIN translation) was split off to IB-REL-13, which remains open. |
+| Last Verified | 2026-08-18 |
 
 ### IB-REL-12: cross_join between two same-named tables from different Ibis connections raises a column-binding error on SQL backends
 
@@ -1289,6 +1290,19 @@ Total divergences tracked: **125**
 | Notes | Verified empirically (backlog item 87, 2026-08-13): Relation.cross_join() raises duckdb BinderException / sqlite OperationalError ("no such column") when the two input tables share a table name but originate from separate Ibis connections (exactly the shape produced by the test suite's BackendDataFrameFactory, which names every table "test_table"); ibis-polars and polars/narwhals are unaffected. Root cause not yet isolated to Ibis vs. mountainash's join visitor — likely a missing table-alias disambiguation when two DatabaseTable operations share a name across connections. Renamed from a colliding DivergenceFact id (was "IB-REL-09", whose yaml entry described a different, no-longer-reproducible "suffixes kwarg" TypeError) when backlog item 87's id-collision detector caught the reuse; the DivergenceFact and this entry now self-reference via upstream_ref. |
 | Last Verified | 2026-08-13 |
 
+### IB-REL-13: ibis-sqlite: asof join raises UnsupportedOperationError
+
+| Field | Value |
+|---|---|
+| Project | ibis |
+| Category | Relational Operations |
+| Root Cause | upstream_feature_gap |
+| Affected Backends | ibis-sqlite |
+| Status | Needs Filing |
+| Workaround | Strict xfail |
+| Notes | Split from IB-REL-11 (2026-08-18) after the ibis-duckdb portion (a nondeterministic row-order bug, not a value divergence) was fixed in mountainash by ordering the join_asof result deterministically. This entry tracks the remaining genuine upstream gap: Ibis has no ASOF JOIN translation for the SQLite backend, so Table.asof_join() raises UnsupportedOperationError on ibis-sqlite. Use a polars or narwhals backend for asof joins on that data. |
+| Last Verified | 2026-08-18 |
+
 ## Aggregate Operations
 
 ### IB-AGG-01: No product aggregate function — no SQL standard equivalent

@@ -69926,32 +69926,31 @@
       "since": "2026-08-06"
     },
     {
-      "id": "IB-REL-11",
-      "kind": "semantics",
+      "id": "IB-REL-12",
+      "kind": "engine_leniency",
       "operation_keys": [],
       "backends": [
         "ibis-duckdb",
         "ibis-sqlite"
       ],
-      "summary": "asof join is unreliable on ibis SQL backends: ibis-duckdb returns a wrong (diverging) result and ibis-sqlite raises UnsupportedOperationError",
-      "impact": "Relation.join_asof() diverges on ibis-duckdb and raises on ibis-sqlite; polars/narwhals compute it correctly",
-      "workaround": "Use a polars or narwhals backend for asof joins",
-      "upstream_ref": "IB-REL-11",
+      "summary": "cross_join between two same-named tables from different Ibis connections raises a column-binding error on ibis SQL backends (ibis-duckdb BinderException, ibis-sqlite OperationalError)",
+      "impact": "Relation.cross_join() raises on ibis-duckdb/ibis-sqlite; polars/narwhals and ibis-polars compute it",
+      "workaround": "Use a polars/narwhals backend or ibis-polars for cross joins",
+      "upstream_ref": "IB-REL-12",
       "since": "2026-08-06"
     },
     {
-      "id": "IB-REL-12",
+      "id": "IB-REL-13",
       "kind": "engine_leniency",
       "operation_keys": [],
       "backends": [
-        "ibis-duckdb",
         "ibis-sqlite"
       ],
-      "summary": "cross_join between two same-named tables from different Ibis connections raises a column-binding error on ibis SQL backends (ibis-duckdb BinderException, ibis-sqlite OperationalError)",
-      "impact": "Relation.cross_join() raises on ibis-duckdb/ibis-sqlite; polars/narwhals and ibis-polars compute it",
-      "workaround": "Use a polars/narwhals backend or ibis-polars for cross joins",
-      "upstream_ref": "IB-REL-12",
-      "since": "2026-08-06"
+      "summary": "ibis-sqlite: asof join raises UnsupportedOperationError — no ASOF JOIN translation",
+      "impact": "Relation.join_asof() raises on ibis-sqlite; polars/narwhals and ibis-duckdb compute it correctly",
+      "workaround": "Use a polars or narwhals backend for asof joins",
+      "upstream_ref": "IB-REL-13",
+      "since": "2026-08-18"
     },
     {
       "id": "IB-STR-11",

@@ -538,8 +538,8 @@ Cells whose facts are all scoped (dialect / parameter / option / value-class) ha
 | IB-MATH-06 | engine_leniency | ibis-polars, ibis-duckdb | `SINH`, `COSH`, `TANH`, `ASINH`, `ACOSH`, `ATANH` | ibis-polars and ibis-duckdb lack hyperbolic math functions in the mountainash arithmetic system; these ops raise NotImplementedError (ibis-sqlite is a separate engine limitation, IB-MATH-02) | sinh/cosh/tanh/asinh/acosh/atanh raise on ibis-polars and ibis-duckdb; polars computes them | Use a polars backend for hyperbolic functions | — | 2026-08-06 |
 | IB-REL-06 | engine_leniency | ibis-duckdb | — | DuckDB rejects tables containing untyped all-NULL columns | Projections whose column is entirely null raise a type resolution error | cast the null column to an explicit type first | IB-REL-06 | 2026-07-05 |
 | IB-REL-10 | engine_leniency | ibis-sqlite | — | ibis-sqlite lacks array/pivot relational translations: drop_nans, unpivot/melt raise OperationNotDefinedError | Relation.drop_nans()/unpivot()/melt() raise on ibis-sqlite; other backends compute them | Use ibis-duckdb or a polars/narwhals backend for these relational ops | IB-REL-10 | 2026-08-06 |
-| IB-REL-11 | semantics | ibis-duckdb, ibis-sqlite | — | asof join is unreliable on ibis SQL backends: ibis-duckdb returns a wrong (diverging) result and ibis-sqlite raises UnsupportedOperationError | Relation.join_asof() diverges on ibis-duckdb and raises on ibis-sqlite; polars/narwhals compute it correctly | Use a polars or narwhals backend for asof joins | IB-REL-11 | 2026-08-06 |
 | IB-REL-12 | engine_leniency | ibis-duckdb, ibis-sqlite | — | cross_join between two same-named tables from different Ibis connections raises a column-binding error on ibis SQL backends (ibis-duckdb BinderException, ibis-sqlite OperationalError) | Relation.cross_join() raises on ibis-duckdb/ibis-sqlite; polars/narwhals and ibis-polars compute it | Use a polars/narwhals backend or ibis-polars for cross joins | IB-REL-12 | 2026-08-06 |
+| IB-REL-13 | engine_leniency | ibis-sqlite | — | ibis-sqlite: asof join raises UnsupportedOperationError — no ASOF JOIN translation | Relation.join_asof() raises on ibis-sqlite; polars/narwhals and ibis-duckdb compute it correctly | Use a polars or narwhals backend for asof joins | IB-REL-13 | 2026-08-18 |
 | IB-STR-11 | engine_leniency | ibis-polars | `CONTAINS`, `STARTS_WITH`, `ENDS_WITH` | ibis-polars rejects case-insensitive string matching (contains/starts_with/ends_with with case_sensitive=False) — UnsupportedArgumentError | case-insensitive contains/starts_with/ends_with raise on ibis-polars; other backends compute them | Use ibis-duckdb/ibis-sqlite or a polars/narwhals backend for case-insensitive matching | IB-STR-11 | 2026-08-06 |
 | IB-TYPE-02 | semantics | ibis-duckdb, ibis-sqlite | `IS_NAN`, `FILL_NAN` | SQL engines treat NaN as NULL; NaN == NaN yields NULL not False | is_nan/fill_nan/NaN comparisons diverge on SQL engines | Use is_null/fill_null on SQL backends | IB-TYPE-02 | 2026-07-05 |
 | IB-TYPE-04 | type_inference | ibis-duckdb, ibis-polars, ibis-sqlite | — | Ibis defers type resolution to its backend, unlike eager Polars | Type-sensitive operations and result comparisons can differ despite matching values | — | IB-TYPE-04 | 2026-07-05 |

@@ -603,23 +603,47 @@ issues:
 - id: IB-REL-11
   project: ibis
   category: relation-ops
-  summary: asof join is unreliable on Ibis SQL backends
-  root_cause: upstream_bug
+  summary: 'RESOLVED: ibis-duckdb asof join returned nondeterministic row order'
+  root_cause: mountainash_internal
   affected_backends:
   - ibis-duckdb
+  upstream_issue: null
+  upstream_issue_filed_by: null
+  status: resolved_in_mountainash
+  our_workaround: none
+  notes: 'Originally described as "asof join is unreliable on Ibis SQL backends"
+    covering both ibis-duckdb and ibis-sqlite. Root-caused (2026-08-18, PR #297
+    CI investigation): Relation.join_asof() on the Ibis backend never applied an
+    explicit ORDER BY, and DuckDB gives no row-order guarantee for ASOF JOIN
+    output absent one — the query planner nondeterministically returned rows in
+    original or shuffled order run-to-run, flipping the strict-xfail test between
+    XFAIL and XPASS(strict) independent of any test-suite change. Not a value
+    divergence — the join values were always correct, only positional-assertion
+    row order flapped. Fixed by ordering the Ibis join_asof result by the join
+    key(s) (relsys_ib_ext_ma_util.py) to match polars/narwhals'' left-order
+    preservation. The distinct ibis-sqlite raise (SQLite has no ASOF JOIN
+    translation) was split off to IB-REL-13, which remains a genuine open gap.
+    Renamed from a colliding DivergenceFact id (was "IB-REL-08") 2026-08-13;
+    that history stands, this entry is now closed.'
+  last_verified: '2026-08-18'
+- id: IB-REL-13
+  project: ibis
+  category: relation-ops
+  summary: 'ibis-sqlite: asof join raises UnsupportedOperationError'
+  root_cause: upstream_feature_gap
+  affected_backends:
   - ibis-sqlite
   upstream_issue: null
   upstream_issue_filed_by: null
-  status: needs_investigation
+  status: needs_filing
   our_workaround: xfail_strict
-  notes: 'Relation.join_asof() returns a diverging (wrong) result on ibis-duckdb and
-    raises UnsupportedOperationError on ibis-sqlite; polars/narwhals compute it
-    correctly. Renamed from a colliding DivergenceFact id (was "IB-REL-08", which
-    already named an unrelated entry above — the backend rename-mapping-inverted
-    gap) when backlog item 87''s id-collision detector caught the reuse; the
-    DivergenceFact and this entry now self-reference via upstream_ref (backlog
-    item 87, 2026-08-13).'
-  last_verified: '2026-08-13'
+  notes: 'Split from IB-REL-11 (2026-08-18) after the ibis-duckdb portion (a
+    nondeterministic row-order bug, not a value divergence) was fixed in
+    mountainash by ordering the join_asof result deterministically. This entry
+    tracks the remaining genuine upstream gap: Ibis has no ASOF JOIN translation
+    for the SQLite backend, so Table.asof_join() raises UnsupportedOperationError
+    on ibis-sqlite. Use a polars or narwhals backend for asof joins on that data.'
+  last_verified: '2026-08-18'
 - id: IB-REL-12
   project: ibis
   category: relation-ops

@@ -670,15 +670,15 @@ def _all() -> tuple[DivergenceFact, ...]:
             since="2026-08-06",
         ),
         DivergenceFact(
-            id="IB-REL-11",
-            kind=DivergenceKind.SEMANTICS,
+            id="IB-REL-13",
+            kind=DivergenceKind.ENGINE_LENIENCY,
             operation_keys=(),  # relation op join_asof
-            backends=("ibis-duckdb", "ibis-sqlite"),
-            summary="asof join is unreliable on ibis SQL backends: ibis-duckdb returns a wrong (diverging) result and ibis-sqlite raises UnsupportedOperationError",
-            impact="Relation.join_asof() diverges on ibis-duckdb and raises on ibis-sqlite; polars/narwhals compute it correctly",
+            backends=("ibis-sqlite",),
+            summary="ibis-sqlite: asof join raises UnsupportedOperationError — no ASOF JOIN translation",
+            impact="Relation.join_asof() raises on ibis-sqlite; polars/narwhals and ibis-duckdb compute it correctly",
             workaround="Use a polars or narwhals backend for asof joins",
-            upstream_ref="IB-REL-11",
-            since="2026-08-06",
+            upstream_ref="IB-REL-13",
+            since="2026-08-18",
         ),
         DivergenceFact(
             id="IB-REL-12",

@@ -197,4 +197,12 @@ def join_asof(
             kwargs["by"] = by
         if tolerance is not None:
             kwargs["tolerance"] = tolerance
-        return left.asof_join(right, **kwargs)
+        result = left.asof_join(right, **kwargs)
+        # Ibis's SQL backends (duckdb, sqlite) give no row-order guarantee for
+        # ASOF JOIN output absent an explicit ORDER BY. An asof join is defined
+        # over data pre-sorted by `on`, so restoring that order here is the
+        # correct, deterministic result — it matches polars/narwhals, which
+        # preserve left input order. Without this, results were flaky rather
+        # than wrong (see docs/known-divergences.md IB-REL-11, resolved).
+        order_cols = [*by, on] if by else [on]
+        return result.order_by(order_cols)
@@ -146,7 +146,7 @@ Buckets: `migrated` (derivable from the spine today), `retained` (a LITERAL_ONLY
 | tests/relations/cross_backend/test_rel_extension_ops_results.py:39 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('NW-REL-01') — migrated |
 | tests/relations/cross_backend/test_rel_extension_ops_results.py:40 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('NW-REL-02') — migrated |
 | tests/relations/cross_backend/test_rel_extension_ops_results.py:41 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('MA-REL-01') — migrated |
-| tests/relations/cross_backend/test_rel_join_results.py:42 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('IB-REL-11') — migrated |
+| tests/relations/cross_backend/test_rel_join_results.py:42 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('IB-REL-13') — migrated |
 | tests/relations/cross_backend/test_terminal_scalar_aggregates.py:13 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('IB-AGG-05') — migrated |
 | tests/relations/cross_backend/test_terminal_scalar_aggregates.py:14 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('NW-AGG-03') — migrated |
 | tests/relations/test_relation_aliases.py:23 | static-marker | UNRESOLVED | UNRESOLVED | UNRESOLVED | None | spine-derived id-keyed divergence mark via xfail_divergence('IB-REL-10') — migrated |

@@ -39,7 +39,7 @@ def sorted_dicts(dicts: list[dict], by: str | list[str]) -> list[dict]:
 from fixtures.capability_gating import xfail_divergence
 
 _ASOF = [
-    pytest.param(b, marks=xfail_divergence("IB-REL-11", backend=b)) for b in ALL_BACKENDS
+    pytest.param(b, marks=xfail_divergence("IB-REL-13", backend=b)) for b in ALL_BACKENDS
 ]
 
 @pytest.mark.cross_backend