fix(hyperdx): tolerate JSON-encoded array/number params from MCP transport

[vibegui]

Summary

A real HyperDX MCP session against the deployed worker (sites-hyperdx.decocache.com/mcp) hit repeated zod validation failures because the MCP transport was JSON-encoding structured params before delivering them:

• QUERY_CHART_DATA — series rejected as string (expected "array", received "string") — 6+ failures
• GET_LOG_DETAILS — groupBy rejected as string — 2–3 failures
• SEARCH_LOGS — limit rejected as string — 1 failure

Some MCP bridges stringify nested arrays/numbers, which is awkward for the agent to recover from. The fix is to make our input schemas tolerant on both shapes.

Changes

• New hyperdx/server/lib/coerce.ts: tiny helpers
  • arr(schema) — z.preprocess that JSON-parses string inputs that look like arrays/objects, then defers to the inner schema
  • num() — z.coerce.number()
• Wrap every input array/number across HyperDX tools (hyperdx.ts, dashboards.ts, alerts.ts) and shared schemas (types.ts)
• Output schemas untouched — issue is one-directional (client → server)
• Mirrors the pattern already in vtex/server/tools/custom/reorder-collection.ts
• Adds coerce.test.ts (12 tests) covering passthrough, JSON parsing, malformed fallthrough, optional/default, nested object arrays, numeric coercion, and end-to-end queryChartDataInputSchema parsing of stringified series + nested stringified groupBy

Test plan

• bun test (47 pass, 0 fail across hyperdx)
• bun run build (compiles cleanly)
• Smoke test: queryChartDataInputSchema.parse({ series: '[{...}]', granularity: '5 minute' }) succeeds
• Smoke test: { groupBy: '["service","level"]', limit: "100" } parses to { groupBy: ["service","level"], limit: 100 }
• After merge + deploy, retry the failing calls from the original session against the live MCP

🤖 Generated with Claude Code

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Summary by cubic

Allows HyperDX tools to accept JSON-encoded arrays/objects and numeric strings from some MCP transports, fixing validation errors on inputs like series, groupBy, and limit. Improves compatibility with real MCP sessions without changing outputs.

• Bug Fixes
  • Added arr() and num() coercion helpers in hyperdx/server/lib/coerce.ts to parse JSON-looking strings and numeric strings before validating with zod.
  • Applied to all array/number inputs in hyperdx.ts, dashboards.ts, alerts.ts, and shared schemas in types.ts. Output schemas unchanged.
  • Added coerce.test.ts with unit tests and an end-to-end parse test for queryChartDataInputSchema.

^{Written for commit 4a22a81. Summary will update on new commits.}