fix(core): preserve jsonSchema adapter after Zod v4 tool schema injection by Souravrajvi0 · Pull Request #21187 · mastra-ai/mastra

Souravrajvi0 · 2026-08-10T18:43:07Z

Description

CoreToolBuilder injects _background / suspendedToolRunId / resumeData onto Zod v4 tool input schemas via safeExtendZodObject. That returns a fresh ZodObject which can drop a custom ~standard.jsonSchema adapter installed by toStandardSchema / createTool().

When downstream code calls standardSchemaToJSONSchema on the mutated schema, invalid tool input can crash with Cannot read properties of undefined (reading 'input') instead of returning a structured validation error.

This mirrors the normalization already done in the non-Zod-v4 JSON Schema fallback path and in validateToolInput (#19030), but applies it at the point where the schema is mutated.

Related issue(s)

Fixes #21170

Type of change

Bug fix (non-breaking change that fixes an issue)

Checklist

I have linked the related issue(s) in the description above
I have added tests that prove my fix is effective or that my feature works

ELI5

When the tool adds extra input fields, it now keeps the schema’s validation helper. Invalid inputs return structured validation errors instead of causing a crash.

Changes

Re-wrap extended Zod v4 schemas with toStandardSchema.
Preserve custom ~standard.jsonSchema adapters.
Add a regression test for malformed background input.
Add a patch changeset for @mastra/core.

…tion Re-wrap extended Zod v4 input schemas with toStandardSchema after CoreToolBuilder injects background/resume override fields. Without this, safeExtendZodObject can drop a custom ~standard.jsonSchema adapter and schema-invalid tool calls crash instead of returning validation errors. Fixes mastra-ai#21170

vercel · 2026-08-10T18:43:13Z

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changeset-bot · 2026-08-10T18:43:15Z

🦋 Changeset detected

Latest commit: a5c5898

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

This PR includes changesets to release 25 packages

Name	Type
@mastra/core	Patch
@mastra/code-sdk	Patch
mastracode	Patch
@mastra/factory	Patch
@mastra/mcp-docs-server	Patch
@internal/playground	Patch
@mastra/client-js	Patch
@mastra/opencode	Patch
@mastra/longmemeval	Patch
mastra	Patch
@mastra/deployer-cloud	Patch
@mastra/react	Patch
@mastra/playground-ui	Patch
@mastra/server	Patch
@mastra/deployer	Patch
create-mastra	Patch
create-factory	Patch
@mastra/express	Patch
@mastra/fastify	Patch
@mastra/hono	Patch
@mastra/koa	Patch
@mastra/nestjs	Patch
@mastra/next	Patch
@mastra/tanstack-start	Patch
@mastra/temporal	Patch

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dane-ai-mastra · 2026-08-10T18:43:21Z

PR triage

Linked issue check passed (#21170).

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PR complexity score

Factor	Value	Score impact
Files changed	3	+6
Lines changed	47	+0
Author merged PRs	1	-1
Test files changed	Yes	-10
Final score		-5

Applied label: complexity: low

Changed test gate

Changed Test Gate is pending. The Changed Test Gate / changed-tests check will update the test label when it completes.

coderabbitai · 2026-08-10T18:43:34Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Review profile: ASSERTIVE

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Run ID: 39d3fb15-2bc3-4e49-af22-33c9482b886c

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Reviewing files that changed from the base of the PR and between 796feee and a5c5898.

📒 Files selected for processing (3)

.changeset/coretoolbuilder-zod-v4-jsonschema-adapter.md
packages/core/src/tools/tool-builder/background-override-injection.test.ts
packages/core/src/tools/tool-builder/builder.ts

Walkthrough

This change re-wraps extended Zod v4 input schemas with toStandardSchema during background or resume field injection. Regression coverage verifies JSON Schema support, injected properties, and structured validation errors.

Changes

Zod v4 adapter preservation

Layer / File(s)	Summary
Schema re-wrapping and regression coverage `packages/core/src/tools/tool-builder/builder.ts`, `packages/core/src/tools/tool-builder/background-override-injection.test.ts`, `.changeset/coretoolbuilder-zod-v4-jsonschema-adapter.md`	`CoreToolBuilder` wraps extended Zod v4 schemas with `toStandardSchema` before storage. The regression test verifies JSON Schema metadata, injected properties, malformed input handling, and executor suppression. The changeset documents the patch.

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

Possibly related PRs

mastra-ai/mastra#19030: Both changes normalize Zod v4 and Standard Schema metadata for structured validation.
mastra-ai/mastra#19701: Both changes update builder.ts schema handling and execution-time validation.

Suggested reviewers: danielslew, wardpeet

🚥 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 describes preserving the JSON Schema adapter after Zod v4 schema injection, despite exceeding the ideal length.
Linked Issues check	✅ Passed	The code re-wraps extended Zod v4 schemas and adds regression coverage for adapter preservation and structured validation errors [`#21170`].
Out of Scope Changes check	✅ Passed	All changes support the linked bug fix through the implementation, regression test, and changeset documentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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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
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/core/src/tools/tool-builder/background-override-injection.test.ts`:
- Around line 155-180: Extend the regression test around CoreToolBuilder to
invoke the built tool’s validation path with malformed _background data such as
enabled: 'yes', and assert it returns a structured validation error rather than
throwing a TypeError. If resumable-tool coverage is absent, add equivalent
invalid-input checks for suspendedToolRunId and resumeData.

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Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: d84bc5b6-c221-4859-a0b7-17f48593ed29

📥 Commits

Reviewing files that changed from the base of the PR and between e3a0621 and 0f71bbf.

📒 Files selected for processing (3)

.changeset/coretoolbuilder-zod-v4-jsonschema-adapter.md
packages/core/src/tools/tool-builder/background-override-injection.test.ts
packages/core/src/tools/tool-builder/builder.ts

mastra-platform

Approved. The one-line normalization at packages/core/src/tools/tool-builder/builder.ts:310 correctly restores a Mastra ~standard.jsonSchema adapter after Zod v4 .extend() injection while preserving the existing Zod validator. The regression test directly covers adapter retention and injected JSON Schema properties, and the existing suite covers valid execution plus resume/background field composition.\n\nVerification (credentials stripped):\n- pnpm build:core — passed (14/14 tasks)\n- focused Vitest background-override-injection.test.ts — passed (11/11)\n- git diff --check — passed\n- package check was attempted but is currently blocked by broad pre-existing workspace/type-resolution errors unrelated to this 3-file change; after the required build, the focused test reports no type errors.\n\nSecurity: no dependency, lockfile, workflow, prompt-processing, install-hook, or test-time execution changes. The patch only wraps an in-memory schema and adds a unit test/changeset.\n\nNon-blocking: CodeRabbit's suggestion to exercise malformed _background through the built tool would strengthen end-to-end regression coverage, but adapter presence plus the existing validation path is sufficient for this surgical fix. The two failing Vercel checks are authorization-gated previews for unrelated docs/playground targets.

mastra-platform · 2026-08-11T09:19:40Z

Factory review handoff: APPROVE at head 0f71bbf2d66b64173661e41644178939ce7db8f8.\n\nReviewed issue #21170, PR/changed-file history, current review threads and checks, implementation consistency, tests, changeset, and security/install-time risk. The fix is scoped and correct. Local credential-stripped verification passed the core build and all 11 focused tool-builder tests. Remaining Vercel failures require deployment authorization and are unrelated to this core-only patch; the broad core check is presently noisy from unrelated workspace/type-resolution failures. No blocking findings.

Exercise the built tool validation path so the adapter regression cannot return as an unstructured TypeError.\n\nCo-Authored-By: Mastra Code (openai/gpt-5.6-sol) <noreply@mastra.ai>

coderabbitai · 2026-08-11T11:29:30Z

Note

GitHub couldn't provide a complete incremental comparison for this pull request, so CodeRabbit is performing a full review instead. This review may take a little longer.

Souravrajvi0 requested review from DanielSLew, abhiaiyer91 and wardpeet as code owners August 10, 2026 18:43

dane-ai-mastra Bot added the complexity: low Low-complexity PR label Aug 10, 2026

coderabbitai Bot reviewed Aug 10, 2026

View reviewed changes

Comment thread packages/core/src/tools/tool-builder/background-override-injection.test.ts Outdated

mastra-platform Bot approved these changes Aug 11, 2026

View reviewed changes

Ehindero Israel and others added 2 commits August 11, 2026 10:25

test(core): cover malformed background input

650aa2f

Exercise the built tool validation path so the adapter regression cannot return as an unstructured TypeError.\n\nCo-Authored-By: Mastra Code (openai/gpt-5.6-sol) <noreply@mastra.ai>

Merge branch 'main' into feat/coretoolbuilder-zod-v4-schema-adapter-091f

a5c5898

wardpeet merged commit b2f0013 into mastra-ai:main Aug 12, 2026
91 of 94 checks passed

dane-ai-mastra Bot mentioned this pull request Aug 12, 2026

chore: version packages (alpha) #21307

Merged

wardpeet mentioned this pull request Aug 12, 2026

[BUG] CoreToolBuilder drops the ~standard.jsonSchema adapter when injecting background/resume fields on a Zod v4 schema #21170

Closed

coderabbitai Bot mentioned this pull request Aug 13, 2026

Fix createTool output schemas with transforms #21293

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fix(core): preserve jsonSchema adapter after Zod v4 tool schema injection - #21187

fix(core): preserve jsonSchema adapter after Zod v4 tool schema injection#21187
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