fix(contract): preserve empty model fields

[Shgit29]

Linked issue

Fixes #30130

Refs prisma/prisma-next#1070

Summary

Field-less variant models correctly produce fields: {} during PSL interpretation, but contract canonicalization removed that empty object even though fields is a required model property.

This change preserves empty model fields during canonicalization so emitted contracts remain structurally valid.

Testing performed

• pnpm build
• pnpm typecheck
• pnpm lint
• pnpm test:packages
• Targeted @internal/contract tests
• Targeted @internal/mongo-contract-psl tests
• Targeted Mongo emitter tests
• git diff --check

The full package suite had unrelated transient failures under load; the affected package suites passed when rerun separately.

Skill update

n/a — internal only

Checklist

• All commits are signed off (git commit -s) per the DCO. The DCO status check will block merge if any commit is missing a Signed-off-by: trailer.
• I read CONTRIBUTING.md and the change is scoped to one logical concern.
• Tests are updated (or n/a if the change is doc-only / refactor with no behavioural delta).
• The PR title is in TML-NNNN: <sentence-case title> form (Linear ticket prefix + concise title naming the concrete deliverable). See .claude/skills/create-pr/SKILL.md for the full convention.
• The Skill update section above is filled in (or stated n/a — internal only).

Notes for the reviewer

This issue was originally reported as prisma/prisma-next#1070 and has now been re-filed in the current repository as #30130 after Prisma Next moved to prisma/prisma as Prisma ORM v8.

The fix is applied in generic contract canonicalization rather than the Mongo-specific canonicalization hook because fields is a required model property at the framework contract level.

Summary by CodeRabbit

Bug Fixes

• Preserved empty model-field containers during contract canonicalization, preventing field-less variants from losing their expected structure.
• Ensured field-less polymorphic variants remain compatible with Mongo schema validation.
• Maintained consistent canonicalized output without changing existing runtime behavior.

Tests

• Added regression coverage confirming field-less variants retain fields: {} before and after canonicalization and pass Mongo schema validation.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between ca8fe14 and 64df122.

📒 Files selected for processing (2)

• packages/1-framework/0-foundation/contract/src/canonicalization.ts
• packages/2-mongo-family/2-authoring/contract-psl/test/interpreter.polymorphism.test.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• packages/2-mongo-family/2-authoring/contract-psl/test/interpreter.polymorphism.test.ts
• packages/1-framework/0-foundation/contract/src/canonicalization.ts

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📝 Walkthrough

Walkthrough

Canonicalization preserves empty fields objects for field-less polymorphic model variants. A regression test verifies preservation through canonicalization and Mongo schema validation.

Changes

Field-less variant contract handling

Layer / File(s)	Summary
Preserve empty model-field containers packages/1-framework/0-foundation/contract/src/canonicalization.ts	Canonicalization recognizes model field paths and preserves matching empty containers during default omission. Type assertions use blindCast, and object-key sorting retains its runtime behavior.
Validate field-less variants packages/2-mongo-family/2-authoring/contract-psl/test/interpreter.polymorphism.test.ts	A regression test verifies that a field-less Note variant retains fields: {} before and after canonicalization and passes MongoContractSchema validation.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 64df1

The change preserves required empty model fields in emitted contracts and is covered by targeted tests; no actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: preserving empty contract model fields. It is concise and specific.
Linked Issues check	✅ Passed	The canonicalization change preserves fields: {} for field-less variant models. The regression test verifies preservation before and after canonicalization and confirms Mongo schema validation. This s…
Out of Scope Changes check	✅ Passed	The changes are limited to canonicalization behavior, related type-cast refactoring, and regression coverage. All changes support the linked issue objective.

Full details: Linked Issues check

Explanation

The canonicalization change preserves fields: {} for field-less variant models. The regression test verifies preservation before and after canonicalization and confirms Mongo schema validation. This satisfies issue #30130.

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Actionable comments posted: 1

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Verify each finding against current code. Fix only still-valid issues, skip the
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Inline comments:
In
`@packages/2-mongo-family/2-authoring/contract-psl/test/interpreter.polymorphism.test.ts`:
- Line 153: Update both assertions in the polymorphism tests around
modelsOf(ir)['Note'] to verify that fields is exactly an empty object rather
than merely matching an empty subset. Replace each toMatchObject({ fields: {} })
assertion with toHaveProperty('fields', {}) or extract fields and compare it
with toEqual({}).

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Fix all unresolved CodeRabbit comments on this PR:

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between c332c67 and ff9ac5d.

📒 Files selected for processing (2)

• packages/1-framework/0-foundation/contract/src/canonicalization.ts
• packages/2-mongo-family/2-authoring/contract-psl/test/interpreter.polymorphism.test.ts

[Shgit29]

@wmadden I noticed you’ve worked on the contract canonicalization path, so you may be a good person to review this. This fixes prisma/prisma-next#1070 by preserving required empty model fields during canonicalization. I’ve also addressed the feedback on the regression assertions, and the targeted tests pass. Thanks!

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[Shgit29]

@wmadden I re-filed the original Prisma Next issue in the current repo as #30130 and updated this PR to link to it. The bug still reproduces on the latest Prisma ORM v8 main, and the fix/regression test here still applies. Thanks!

[coderabbitai]

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