fix(cll): resolve column lineage for recursive CTEs

[danyelf]

Summary

• Fix recursive CTEs (WITH RECURSIVE) showing "unknown" lineage for all columns instead of tracing back to source tables
• Fix CllColumnDep positional-arg crash that caused the entire model to degrade to "unknown" when any single column was unresolvable (e.g. correlated scalar subqueries, LATERAL joins, PIVOT, UNNEST)
• Add _resolve_scope_cll() helper to handle sqlglot's phantom stub Scopes for self-referential CTE references

Root cause

sqlglot's traverse_scope creates a stub Scope for recursive CTE self-references that shares the same expression object as the base case but isn't yielded in the scope list. scope_cll_map.get(stub) returned None, falling through to a crash path.

Test plan

• test_recursive_cte — full category hierarchy recursive CTE traces all columns to stg_categories
• test_recursive_cte_m2c_propagation — WHERE clause deps from base case propagate through recursive branch
• test_unresolvable_column_does_not_crash_entire_model — correlated scalar subquery degrades gracefully; sibling columns still trace correctly
• All 60 existing CLL tests pass (43 unit + 16 integration + 1 new)

Closes DRC-2890
Related: DRC-2891 (audit of remaining complex SQL patterns)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
recce/util/cll.py	91.26% <100.00%> (+8.91%)	⬆️
tests/util/test_cll.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[danyelf]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

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[Copilot]

Pull request overview

Improves Recce’s column-level lineage (CLL) extraction so recursive CTEs (WITH RECURSIVE) and partially unresolvable columns no longer degrade lineage results to “unknown” for the whole model.

Changes:

• Add scope-resolution fallback (_resolve_scope_cll) to handle sqlglot’s stub Scope objects created for recursive CTE self-references.
• Fix CllColumnDep instantiation to use keyword arguments (node=, column=), avoiding positional-arg crashes.
• Add new CLL tests covering recursive CTE column lineage and model-to-column dependency propagation.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
recce/util/cll.py	Adds stub-scope fallback lookup and hardens dependency collection to avoid crashes and support recursive CTE scope resolution.
tests/util/test_cll.py	Adds regression tests for recursive CTE lineage and for ensuring one unresolvable column doesn’t break sibling column lineage.

[wcchang1115]

LGTM, thanks!