fix(policy): alias relation subquery tables to prevent self-relation shadowing

[ymc9]

Summary

Policy rules that traverse a relation compile into a correlated subquery selecting from the related table. The table was referenced by its bare model name, so when the relation points back to the same model (a self relation), the inner table shadowed the outer row. A condition like parent.tenantId != this.tenantId was evaluated entirely against the inner table and never matched, so the rule silently passed.

Affected shapes (all covered by the new tests):

• @@deny('create' | 'post-update', parent.tenantId != this.tenantId) on a self relation, set via a direct foreign key write
• Read rules through a self relation, e.g. parent.value > this.value
• Collection predicates on a self relation referencing this, e.g. children?[value > this.value]
• Multi-hop chains, e.g. parent.parent.value
• Nested collection predicates traversing the same relation, e.g. children?[c, this.children?[id != c.id && value == c.value]]
• Self many-to-many relations (the implicit join table was also referenced by bare name)

Fix

Every relation subquery now gets a unique alias allocated from a per-transformer counter (e.g. parent$1, children$2, friends$3$join), and all downstream references use it: member chains, collection-predicate filters, binding scopes, and many-to-many joins. The counter is per compiled policy, so the same rule always produces the same SQL, and aliases stay short regardless of chain depth.

Generated SQL before / after for the create check:

-- before
(select "tenantId" from "Item" where "Item"."parentId" = "Item"."id")
-- after
(select "parent$1"."tenantId" from "Item" as "parent$1" where "Item"."parentId" = "parent$1"."id")

Testing

• New tests/e2e/orm/policy/self-relation.test.ts with seven cases; all fail before and pass after.
• Full policy e2e directory, full e2e suite on SQLite, and the regression suite pass.
• Verified against a standalone PGlite/Postgres reproduction.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Fixed policy evaluation for self-referential relationships, including parent/child and many-to-many connections.
  • Corrected nested collection predicates and multi-level relationship queries so comparisons consistently use the intended records.
  • Improved authorization checks for relationship assignments, including cross-tenant updates, same-tenant assignments, and clearing relationships.

• Tests

  • Added coverage for self-relations, nested predicates, multi-hop queries, and relationship-based access control.

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📝 Walkthrough

Walkthrough

The policy expression transformer now assigns unique aliases to nested self-relations and collection predicates. New E2E tests cover nested collection predicates and self many-to-many relations.

Changes

Self-relation policy handling

Layer / File(s)	Summary
Relation alias propagation packages/plugins/policy/src/expression-transformer.ts	The transformer generates unique relation aliases, qualifies relation and join references, and shares the innermost alias between collection predicate filters and relation subqueries.
Self-relation policy validation tests/e2e/orm/policy/self-relation.test.ts	The E2E tests validate nested collection predicates with distinct child bindings and self many-to-many predicates.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix

Merge Risk: 🔵 Low · up to 59498

Policies using sufficiently long self-relation field names can generate invalid PostgreSQL queries. Bound generated aliases before merging.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: aliasing relation subquery tables to prevent self-relation shadowing in policy queries.

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[ymc9]

@claude review

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Actionable comments posted: 1

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Inline comments:
In `@packages/plugins/policy/src/expression-transformer.ts`:
- Line 482: Update newRelationAlias so generated PostgreSQL relation aliases
stay within 63 bytes and remain unique, preferably by basing them on the counter
or truncating the field name while reserving suffix space. Ensure long
self-relation names cannot collide with the many-to-many $join alias, and add a
regression test covering that case.

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📥 Commits

Reviewing files that changed from the base of the PR and between 10ac311 and 5949835.

📒 Files selected for processing (2)

• packages/plugins/policy/src/expression-transformer.ts
• tests/e2e/orm/policy/self-relation.test.ts

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