fix: correct children items schema in POST /v1/pages to use blockObjectRequest ref

[4444J99]

Summary

The OpenAPI spec for POST /v1/pages declares children.items as {"type": "string"}, while the equivalent PATCH /v1/blocks/{block_id}/children endpoint correctly uses {"$ref": "#/components/schemas/blockObjectRequest"}. This inconsistency causes MCP clients to treat block objects as plain strings, producing "Expected object, received string" validation errors when creating pages with content blocks.

Root cause: A single incorrect type declaration in scripts/notion-openapi.json at the POST /v1/pages endpoint's children property.

Fix: Replace {"type": "string"} with {"$ref": "#/components/schemas/blockObjectRequest"} to match the schema already used by PATCH /v1/blocks/{block_id}/children.

Changes

• scripts/notion-openapi.json — Fix children.items type from string to $ref: blockObjectRequest in the POST /v1/pages schema
• src/openapi-mcp-server/openapi/__tests__/parser.test.ts — Add tests verifying children items use $ref (not string) and both page-creation and block-append endpoints produce matching schema structures
• src/openapi-mcp-server/mcp/__tests__/proxy.test.ts — Add test for full-array stringification deserialization (entire children array arriving as a JSON string)

Context

This interacts with two existing defenses already in the codebase:

1. deserializeParams() in proxy.ts (from fix: handle double-serialized JSON parameters from MCP clients #180) handles runtime recovery when clients double-serialize parameters
2. withStringFallback() in parser.ts wraps complex schemas with anyOf: [schema, {type: "string"}] to accept stringified input

This PR fixes the schema declaration so clients receive correct type information upfront, reducing reliance on the runtime workarounds above.

Fixes #82

Test plan

• All 77 tests pass (74 existing + 3 new)
• TypeScript type check passes (tsc --noEmit)
• New parser test: verifies createPage and appendBlockChildren produce matching children schema structure
• New parser test: verifies children.items is not typed as plain string
• New proxy test: verifies full-array stringification (entire children as JSON string) is deserialized correctly

[4444J99]

Gentle ping — this fixes the children.items schema type mismatch for POST /v1/pages (issue #82). All CI checks pass and three new tests are included. Let me know if anything needs adjusting.

[4444J99]

Hi — following up on this. The fix corrects the children.items schema in POST /v1/pages from {"type": "string"} to the proper $ref: blockObjectRequest, matching the existing schema on PATCH /v1/blocks/{block_id}/children. All 77 tests pass. Happy to rebase or adjust.