fix(language): detect @@@onceInModel duplicates across inheritance

[ymc9]

Problem

Field-level attributes marked with @@@onceInModel (e.g. @deletedAt from the soft-delete plugin) may be applied to at most one field per model, including inherited fields. The check ran per-attribute against the model that physically declares each field, so duplicates that only co-occur in a derived model slipped through.

Specifically uncaught: when every field carrying the attribute is inherited from a separate mixin/base (none declared on the leaf model itself). The locally-declared and mixed (one local + one inherited) cases were already caught.

attribute @softDelete() @@@targetField([DateTimeField]) @@@onceInModel
type Base1 { deletedAt DateTime? @softDelete }
type Base2 { removedAt DateTime? @softDelete }
model Foo with Base1 Base2 {   // two @softDelete fields, both inherited -> previously NOT flagged
    id Int @id @default(autoincrement())
}

Fix

Move the check to the model level (DataModelValidator), where getAllFields(dm) already exposes the full inherited field set. Field attributes are grouped by their @@@onceInModel-marked declaration; any group with more than one occurrence is an error. Errors report on the offending local field attributes when present (preserving the per-field diagnostic), falling back to the model declaration when all duplicates are inherited.

The old per-attribute checkOnceInModel (and its now-unused import) is removed.

Tests

• New regression test in attribute-application.test.ts for the inheritance-only (two-mixin) case, alongside the existing local-only and mixed cases.
• Language suite: 84 passed. Soft-delete plugin suite (the real consumer): 15 passed, no regressions. tsc --noEmit clean.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Validation & Constraint Enforcement

  • Improved @@onceInModel attribute validation to properly handle inherited fields and mixins within models, ensuring the "only one field per model" constraint is enforced across the entire model hierarchy.

• Tests

  • Added validation test case for @@onceInModel attribute behavior with inherited field scenarios.

[coderabbitai]

📝 Walkthrough

Walkthrough

The @@onceInModel duplicate-field validation is removed from AttributeApplicationValidator and re-implemented as validateOnceInModelAttributes inside DataModelValidator. The new implementation groups field attributes by their @@@onceInModel declaration reference across all fields including inherited ones, and a new test covers the case where the violation arises purely through mixin composition.

Changes

@@onceInModel Validation Relocation

Layer / File(s)	Summary
Remove checkOnceInModel from AttributeApplicationValidator packages/language/src/validators/attribute-application-validator.ts	Deletes the checkOnceInModel private method and its call-site from validate(), and removes the now-unused getAllFields import.
Add validateOnceInModelAttributes to DataModelValidator + test packages/language/src/validators/datamodel-validator.ts, packages/language/test/attribute-application.test.ts	Adds Attribute and DataFieldAttribute AST imports, wires validateOnceInModelAttributes into DataModelValidator.validate(), implements grouping logic that detects duplicate @@@onceInModel usage across local and inherited fields, and adds a test asserting the error fires when duplicates are introduced exclusively via two mixin inheritances.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A mixin brought two soft-delete fields one day,
The old checker missed them — they slipped right away!
Now DataModelValidator scans every heir,
Groups by declaration with methodical care,
And raises an error when two fields declare.
No sneaky inheritance escapes my stare! 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: fixing validation to detect duplicate @@@onceInModel attributes across inherited fields.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/once-in-model-inheritance

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[coderabbitai]

🧹 Nitpick comments (1)

packages/language/test/attribute-application.test.ts (1)

564-588: ⚡ Quick win

Add one extends-only inheritance regression case too.

Nice addition for the two-mixin path. Since the objective also calls out base-type inheritance, adding a sibling test where duplicates arrive only through an extends chain would close the remaining coverage gap.

Proposed test addition

+        it('rejects when the attribute arrives only through base-model inheritance', async () => {
+            await loadSchemaWithError(
+                `
+                datasource db {
+                    provider = 'sqlite'
+                    url      = 'file:./dev.db'
+                }
+
+                attribute `@softDelete`() @@@targetField([DateTimeField]) @@@onceInModel
+
+                model Base {
+                    id Int `@id` `@default`(autoincrement())
+                    deletedAt DateTime? `@softDelete`
+                    @@delegate
+                }
+
+                model Mid extends Base {
+                    removedAt DateTime? `@softDelete`
+                    @@delegate
+                }
+
+                model Leaf extends Mid {
+                    extra Int?
+                }
+                `,
+                /Attribute "`@softDelete`" can only be applied to one field per model/,
+            );
+        });

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/language/test/attribute-application.test.ts` around lines 564 - 588,
Add a sibling test case after the existing 'rejects when the attribute arrives
only through inheritance (two mixins)' test that verifies the same error
condition but using base-type inheritance through extends instead of mixins. The
new test should create a similar schema structure where the attribute is
duplicated across an extends chain (for example, a Base type with the attribute
that is extended by another Base type which is also extended by a model) to
ensure the validation correctly rejects duplicates arriving through
extends-based inheritance as well, closing the coverage gap for both inheritance
patterns.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@packages/language/test/attribute-application.test.ts`:
- Around line 564-588: Add a sibling test case after the existing 'rejects when
the attribute arrives only through inheritance (two mixins)' test that verifies
the same error condition but using base-type inheritance through extends instead
of mixins. The new test should create a similar schema structure where the
attribute is duplicated across an extends chain (for example, a Base type with
the attribute that is extended by another Base type which is also extended by a
model) to ensure the validation correctly rejects duplicates arriving through
extends-based inheritance as well, closing the coverage gap for both inheritance
patterns.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 8c19ad46-1b60-4e2c-b726-48277b95d222

📥 Commits

Reviewing files that changed from the base of the PR and between 1af9b2b and a2688af.

📒 Files selected for processing (3)

• packages/language/src/validators/attribute-application-validator.ts
• packages/language/src/validators/datamodel-validator.ts
• packages/language/test/attribute-application.test.ts

💤 Files with no reviewable changes (1)

• packages/language/src/validators/attribute-application-validator.ts