fix(mcp): support Codex-compatible input schemas - #500
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Normalize published MCP schemas for Codex compatibility and add build-first static contract baselines for adaptive and full session-default modes. Fixes #491
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Pull request overview
This PR normalizes the published MCP tool input/output JSON schemas at the MCP registration boundary to improve Codex compatibility, and introduces a build-backed “fail-closed” contract-test baseline for the MCP static tool surface.
Changes:
- Normalize MCP input schemas derived from tool Zod shapes to omit
propertyNameswhile keeping Zod parsing constraints intact. - Normalize MCP output registration schemas similarly, and refactor tool registration to centralize the registration config.
- Add a dedicated build-dependent contract-test harness + fixtures and isolate it from the default
npm testVitest run.
Reviewed changes
Copilot reviewed 10 out of 12 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| vitest.contract.config.ts | Adds a dedicated Vitest config for build-backed contract tests. |
| vitest.config.ts | Excludes src/contract-tests/** from the default unit test suite. |
| src/utils/tool-registry.ts | Centralizes MCP tool registration config and normalizes schemas at registration time. |
| src/utils/mcp-input-schema.ts | Implements Codex-focused JSON schema normalization and MCP input-schema wrapping. |
| src/utils/tests/mcp-input-schema.test.ts | Unit tests ensuring schema normalization doesn’t affect parsing behavior. |
| src/core/structured-output-schema.ts | Normalizes output registration JSON schemas for Codex compatibility. |
| src/contract-tests/capture-mcp-tool-contracts.ts | Captures and validates the MCP static tool contract surface via an in-memory MCP client/server. |
| src/contract-tests/tests/mcp-tool-contracts.test.ts | Verifies captured contracts match committed adaptive/full baselines. |
| package.json | Adds test:tool-contracts script to build then run contract tests. |
| CHANGELOG.md | Documents the Codex schema-compatibility fix and new contract baseline gate. |
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| import { z, type ZodType } from 'zod'; | ||
| import { getStructuredOutputSchemasDir } from './resource-root.ts'; | ||
| import { normalizeMcpSchemaForCodex } from '../utils/mcp-input-schema.ts'; | ||
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Expose Codex-compatible MCP wire schemas for record-shaped environment inputs and arbitrary Xcode arguments while preserving object-based CLI and domain inputs. Add build-first, fail-closed per-tool contract fixtures for both public schema modes and validate the complete static catalog. Fixes #491
cameroncooke
changed the title
Require valid domain output schemas on Apple hosts while accepting only specific downstream missing-tool signatures on Linux CI. Refs #491
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Codex 0.31 rejects valid MCP input schemas when a record is represented with a
schema-valued
additionalProperties. Seven environment inputs now use readable{ key, value }arrays on the MCP wire, and Xcode IDE tool arguments use a JSONobject string. Each input is decoded once at the tool boundary; CLI and domain
callers keep their existing object-shaped inputs and normal tool behavior is
unchanged.
Regression coverage captures one readable contract per static MCP tool in both
session-default modes (82 tools × 2). The build-first gate reproduces all eight
historical Codex failures per mode, checks the exact Codex 0.31 conversion
boundary, validates structured-output contracts, exercises live handlers, and
now passes the full catalog with zero incompatibilities.
The full non-update snapshot suite remains red on this host because its stored
fixtures predate the installed Xcode/device environment and AXe cannot load the
missing Xcode
SimulatorKit.framework; the changed Xcode IDE snapshot suitepasses. No unrelated snapshots are updated here.
Fixes #491