fix(sql): validate table qualifiers in single-table scope (SQLR-14)

[joaoh82]

Summary

Fixes SQLR-14: SingleTableScope ignored table qualifiers entirely, so SELECT x.id FROM t, ... WHERE bogus.id = 1, and the UPDATE/DELETE equivalents silently resolved anything.col as plain col. JoinedScope already errored on unknown qualifiers; the single-table path now matches it (and SQLite).

Changes

• SingleTableScope carries a scope_name (FROM alias when declared, else table name) and lookup rejects mismatched qualifiers with JoinedScope's exact wording: unknown table qualifier 'x' in column reference 'x.id'. Matching is ASCII case-insensitive.
• A shared check_single_scope_qualifier helper also guards the schema-level checks that run before any row is visited: projection list, GROUP BY keys, aggregate args — and the index-probe WHERE shape, where try_extract_equality previously stripped the qualifier via parts.last() (so WHERE bogus.name = 'x' on an indexed column bypassed evaluation entirely).
• eval_predicate / eval_expr / sort_rowids / select_topk / select_rowids take the scope name; extract_table_name now returns the FROM alias, so UPDATE / DELETE validate too (WHERE and UPDATE SET right-hand sides, including UPDATE t AS a … / DELETE FROM t AS a …).
• Per SQLite semantics, a declared alias shadows the table name as a qualifier: SELECT t.id FROM t AS a errors — pinned by tests for SELECT, UPDATE, and DELETE.
• Docs: corrected the "we ignore qualifiers" line in docs/sql-engine.md; added a qualified-references bullet to docs/supported-sql.md.

Acceptance criteria

• SELECT t.id FROM t and SELECT a.id FROM t AS a keep working (case-insensitive)
• SELECT x.id FROM t errors with JoinedScope-consistent wording
• Same enforcement in WHERE / ORDER BY for SELECT, UPDATE, DELETE (UPDATE t SET ... WHERE x.id = 1 errors)
• Declared alias is the only valid qualifier (SELECT t.id FROM t AS a errors), matching SQLite — pinned with tests
• Regression matrix covered (14 new tests); audited existing tests for bogus-qualifier usage — none found, zero pre-existing tests broke

Testing

• 655 tests pass (641 pre-existing + 14 new SQLR-14 regression tests)
• cargo fmt --check, cargo clippy, cargo doc clean — warning sets identical to main (verified by stash-diff)
• REPL smoke of the full matrix: bogus qualifiers error on every path (projection, WHERE, indexed WHERE, ORDER BY, GROUP BY, aggregate args, UPDATE SET RHS); valid / alias / case-variant forms return correct rows

Known gaps (follow-ups, not in this PR)

• fts_match(bogus.col, …) / bm25_score extract their column arg syntactically and still strip a qualifier silently (function args need scope-name access in eval_function)
• HAVING x.dept … ignores qualifiers via GroupRowScope — shared with the joined path, so single-table and JOIN behavior remain consistent there

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
rust-sqlite	Ready	Preview, Comment	Jun 11, 2026 2:03pm