fix(schema-to-json): support serializing Zod 4 z.date() to JSON Schema

[kaiizer777]

Fixes #4939

Problem

In @trigger.dev/schema-to-json, converting a Zod 4 schema that includes z.date() threw an uncaught error:

Date cannot be represented in JSON Schema

This crashed MCP tools/list responses as well as schema generation/indexing when task payloads or tools utilized z.date().

Root Cause

convertZod4Schema in packages/schema-to-json/src/index.ts called z4.toJSONSchema(schema, ...) without configuring an unrepresentable handler. In Zod 4, dateProcessor invokes handleUnrepresentable, which defaults to "throw".

Solution

1. Configured unrepresentable in z4.toJSONSchema to map date nodes to { type: "string", format: "date-time" }, achieving parity with Zod 3 (zod-to-json-schema).
2. Maintained strict "throw" behavior for other unrepresentable types (e.g. undefined, symbol).
3. Added date formatting in override to ensure schema consistency.
4. Added unit tests for z.date() standalone and nested in objects with optional/nullable/array wrappers across both Zod 4 and minimum Zod 3 permalink.
5. Added user-facing patch changeset for @trigger.dev/schema-to-json.

Verification

• pnpm --filter "@trigger.dev/schema-to-json" run test -- --run (25 passed)
• pnpm --filter trigger.dev run test src/mcp/schemas.test.ts -- --run (20 passed)
• pnpm run build --filter "@trigger.dev/schema-to-json"
• pnpm exec oxfmt packages/schema-to-json/src/index.ts packages/schema-to-json/tests/index.test.ts
• pnpm exec oxlint packages/schema-to-json/src/index.ts packages/schema-to-json/tests/index.test.ts

[changeset-bot]

🦋 Changeset detected

Latest commit: ccad17a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
@trigger.dev/schema-to-json	Patch
trigger.dev	Patch
@internal/dashboard-agent	Patch
@trigger.dev/build	Patch
@trigger.dev/core	Patch
@trigger.dev/python	Patch
@trigger.dev/react-hooks	Patch
@trigger.dev/redis-worker	Patch
@trigger.dev/rsc	Patch
@trigger.dev/sdk	Patch
@trigger.dev/database	Patch
@trigger.dev/otlp-importer	Patch
@trigger.dev/rbac	Patch
@trigger.dev/sso	Patch
@internal/clickhouse	Patch
@internal/llm-model-catalog	Patch
@internal/metrics-pipeline	Patch
@internal/redis	Patch
@internal/replication	Patch
@internal/run-engine	Patch
@internal/run-store	Patch
@internal/schedule-engine	Patch
@internal/tracing	Patch
@internal/webhook-engine	Patch
@internal/webhook-sources	Patch
@internal/testcontainers	Patch
@internal/cache	Patch

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[github-actions]

Hi @kaiizer777, thanks for your interest in contributing!

This project requires that pull request authors are vouched, and you are not in the list of vouched users.

This PR will be closed automatically. See https://github.com/triggerdotdev/trigger.dev/blob/main/CONTRIBUTING.md for more details.

[coderabbitai]

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📒 Files selected for processing (3)

• .changeset/fix-zod4-date-json-schema.md
• packages/schema-to-json/src/index.ts
• packages/schema-to-json/tests/index.test.ts

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[devin-ai-integration]

Devin Review found 1 potential issue.

[devin-ai-integration]

🟡 Older Zod versions weaken schemas

With Zod 4.0–4.4, the unrepresentable function disables throwing for non-date types. Those releases only compare the option with "throw", so unsupported schemas become {} and accept rejected values.

Learn more

The package accepts Zod ^4.0.0, but function-valued unrepresentable handlers were added only in later Zod 4 releases. Earlier releases treat every value except the literal "throw" as permissive behavior. The callback therefore never runs there, although the existing override still converts dates. Other unrepresentable nodes lose their previous errors and emit unconstrained schemas.

Example: With Zod 4.1, converting z.symbol() previously throws. After this change it emits {}, which permits strings and numbers even though z.symbol() rejects them.

Recommended fix: Either raise both Zod dependency ranges to the first version supporting UnrepresentableHandler, or preserve compatibility by detecting that capability and explicitly throwing from override for every non-date unrepresentable node on older releases. Add a test installed against the minimum supported Zod 4 version.

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