Remove enum declaration-order SQL rewriting - #30223

Linked issue

n/a — small change; no ticket.

At a glance

ORDER BY "Task"."priority" ASC, "Task"."id" ASC

For a text-backed enum declared as low, high, medium, this now sorts by stored value: high, low, medium, rather than wrapping the column in array_position(...).

Summary

Enum metadata should not silently change SQL ordering. Remove the declaration-order rewrite and let the database evaluate the original expressions.

Decision

Render ORDER BY and DISTINCT ON expressions normally, without consulting enum value sets.

Notes for the reviewer

This changes text-backed enum ordering. PostgreSQL native enum types retain PostgreSQL's own declaration-order semantics: this PR introduces no casts or replacement ordering policy. Schema, codecs, and enum member declarations are unchanged.

How it fits together

1. Use the regular expression renderer for ordering.
2. Do the same for DISTINCT ON, preserving its expression match with ORDER BY.
3. Remove the now-unused table-source lookup and enum-order helpers.

Behavior changes & evidence

• Qualified and unqualified enum columns sort by stored value, including normal ASC NULL placement; DISTINCT ON keeps the original expression. Implementation: sql-renderer.ts. SQL and PGlite execution evidence: order-by-enum.integration.test.ts.

Testing performed

• PostgreSQL adapter suite: 867 passed, 3 expected failures, 1 skipped.
• Enum ordering integration suite rerun after commit formatting: 7 passed.
• PostgreSQL adapter typecheck: passed.
• Biome checks, focused dependency lint, and git diff --check: passed.

Skill update

No skill update required: query authoring APIs are unchanged, and the adapter now follows the database's ordinary ordering semantics rather than introducing an enum-specific convention.

Checklist

• All commits are DCO signed off.
• I read CONTRIBUTING.md; this change is scoped to one logical concern.
• Tests are updated.
• The PR title uses a Linear ticket prefix — not applicable; no ticket.
• The Skill update section is filled in.

Alternatives considered

• Keep declaration-order emulation: rejected because enum metadata should not override the requested SQL expression.
• Cast native PostgreSQL enums to text: not chosen because the requested behavior is to leave ORDER BY unchanged, not impose another sorting policy.

Summary by CodeRabbit

• Bug Fixes
  • PostgreSQL enum-backed columns now sort by their stored text values rather than enum declaration order.
  • ORDER BY and DISTINCT ON queries retain straightforward column expressions, including when handling NULL values.