SLT conformance gap triage (foundation-port baseline)

[zfarrell]

Tracking issue for the 96 failing sqllogictest cases on the post-rebase upstream-port/integration branch produced by #12.

Baseline: 180 / 276 SLT tests passing (65%). Was 158 / 254 (62%) on the pre-rebase ducklake-features/integration branch.

Each category below is a follow-up workstream. None of these are blocking #12 acceptance; #12 explicitly defers SLT-fix work.

Failures by category

Count	Category	Sample test	Failure mode
21	add_files/*	add_files_missing_fields	query result mismatch (mostly hybrid-mode add_files quirks; some real conformance gaps)
17	alter/*	alter_timestamptz_promotion	mix of struct evolution (add_column_nested, drop_column_nested, struct_evolution*) and type-promotion mismatches
9	macros/*	test_attach_timetravel	DuckLake extension does not support functions — upstream blocker, not our issue
9	data_inlining/*	basic_data_inlining	hybrid-mode limitation: DuckDB writes inlined data, DataFusion reads only the Parquet side
6	types/*	all_types	unsupported nested types (list/map/struct) + table-not-found planning fallout
6	transaction/*	concurrent_table_creation	within-transaction visibility: uncommitted data not visible to DataFusion's read side
4	compaction/*	compaction_full_file_delete	query result mismatch; partly affected by the dropped compaction_functions.rs pass-through
3	concurrent/*	concurrent_insert_data_inlining	data-inlining hybrid-mode limitation
2	rowid/*	ducklake_row_id_update	the row_id reconciliation tracked in #22
2	rewrite_data_files/*	test_rewrite_concurrency	query result mismatch (compaction-adjacent)
2	partitioning/*	disable_hive_partitioning	table-not-found planning failure (path-style table reference)
2	merge/*	merge_update_insert	table-not-found planning failure
2	default/*	—	default expression evaluation
1 each	virtualcolumns, view, time, table, settings, secrets, remove, insert, cloud, audit, attach	various	misc one-off

Suggested follow-up tickets

• add_files/* triage (21) — most are hybrid-mode quirks but some are real conformance issues (NULL handling, struct display, column ordering after add_files). Worth its own ticket.
• alter/* struct evolution (12 of the 17) — depends on ALTER/DROP/CREATE schema evolution DDL #20 ALTER/DROP/CREATE schema evolution.
• data_inlining/* + concurrent/* data-inlining hybrid (12) — fundamental hybrid-test-mode limitation; consider documenting as expected-fail or rewriting tests in pure-DF mode.
• transaction/* (6) — depends on a real transactional read model; significant scope.
• compaction/* + rewrite_data_files/* (6) — blocked on native compaction reintroduction.
• macros/* (9) — upstream DuckLake extension limitation, NOT our issue. Skip-list these.
• partitioning/* + merge/* table-not-found (4) — SQL parsing / table resolution bug; small ticket.
• One-off failures (≈10) — investigate individually.

How to reproduce

```
git checkout upstream-port/integration
cargo test --features write-sqlite --test sqllogictest_runner
```

Tracks #12.