fix(mcp): handle JSON-serialized object parameters from MCP clients#5611
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bobey wants to merge 2 commits intoHelicone:mainfrom
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fix(mcp): handle JSON-serialized object parameters from MCP clients#5611bobey wants to merge 2 commits intoHelicone:mainfrom
bobey wants to merge 2 commits intoHelicone:mainfrom
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Some MCP clients serialize complex object parameters (filter, sort) as JSON strings rather than native objects. Add a z.preprocess wrapper that transparently parses JSON strings before Zod validation, keeping all existing schema validation intact. Closes Helicone#5610
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Extract jsonPreprocess into its own module for testability. Add vitest with 8 tests covering: - native objects passed through unchanged - JSON strings parsed before validation - "all" literal preserved - invalid JSON rejected by schema - nested filter schemas - sort schemas
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Summary
Some MCP clients (e.g. Claude Code) serialize complex object parameters as JSON strings rather than native JavaScript objects. This causes Zod validation to reject valid filter/sort values with
invalid_typeerrors (expected: object, received: string).This PR adds a
z.preprocesswrapper that transparently parses JSON strings before Zod validation runs, keeping all existing schema validation intact.Affected parameters:
filteronquery_requestssortonquery_requestsfilteronquery_sessionsCloses #5610