{
  "$schema": "https://ui.shadcn.com/schema/registry-item.json",
  "name": "middleware-trpc",
  "title": "tRPC Middleware",
  "description": "tRPC middleware that annotates the ambient request wide event with trpc fields (pair with the Next.js route-handler wrapper).",
  "type": "registry:lib",
  "docs": "Wire into your procedure bases: `const amplioMiddleware = t.middleware(amplioTrpcMiddleware())` then `.use(amplioMiddleware)` on publicProcedure/protectedProcedure. In a create-t3-app layout, `npx @useamplio/cli@alpha init --wire` edits src/server/api/trpc.ts for you.",
  "dependencies": [
    "@useamplio/amplio@^0.1.0-alpha.15"
  ],
  "files": [
    {
      "path": "registry/middleware/trpc.ts",
      "target": "~/telemetry/middleware/trpc.ts",
      "type": "registry:lib",
      "content": "/**\n * Amplio tRPC middleware. Like create-t3-app's own trpc.ts, you likely never\n * need to read or modify this file — wire amplioTrpcMiddleware() into your\n * procedure bases and you're done.\n *\n * Product stance:\n * ONE wide event per unit of work: the HTTP wrapper (withAmplio) owns the request\n * wide event (the spine). This middleware ANNOTATES that event with trpc.* fields\n * instead of emitting a sibling record. Domain events emitted in procedures are\n * intentionally separate rows — do not duplicate fields across them.\n */\n// Side-effect import: ensures init() from telemetry/logger runs in every module\n// graph that uses this middleware (next dev --turbo compiles instrumentation.ts\n// and route bundles separately, which would otherwise drop events silently).\nimport \"../logger\";\n\nimport {\n  createLogger,\n  createRequestId,\n  getLogger,\n  hasAmbientLogger,\n  runWithLogger,\n  scheduleFlush,\n  trpcErrorHttpStatus,\n  type Logger,\n} from \"@useamplio/amplio\";\n\ntype TrpcProcedureType = \"query\" | \"mutation\" | \"subscription\";\n\ntype TrpcProcedureRef = { path: string; type: TrpcProcedureType };\n\nconst batchedProcedures = new WeakMap<Logger, TrpcProcedureRef[]>();\n\nfunction isFailedMiddlewareResult(\n  result: unknown,\n): result is { ok: false; error: unknown } {\n  return (\n    result !== null &&\n    typeof result === \"object\" &&\n    \"ok\" in result &&\n    (result as { ok: unknown }).ok === false &&\n    \"error\" in result\n  );\n}\n\nfunction annotateTrpcProcedure(\n  logger: Logger,\n  path: string,\n  type: TrpcProcedureType,\n): void {\n  if (logger.sealed) {\n    return;\n  }\n\n  // Count every invocation — a batch of two calls to the SAME procedure is two\n  // units of work and must not be deduplicated away.\n  const entry: TrpcProcedureRef = { path, type };\n  const seen = batchedProcedures.get(logger) ?? [];\n  const updated = [...seen, entry];\n  batchedProcedures.set(logger, updated);\n\n  if (updated.length === 1) {\n    logger.set({ trpc: { path, type } });\n    return;\n  }\n\n  // A batch has no single path — null the scalar fields so dashboards that\n  // group by trpc.path never mix \"the request was for X\" with \"X happened to\n  // be first in a batch\". The full list lives in trpc.procedures; a failing\n  // procedure lands in trpc.failed_path (see annotateTrpcError).\n  logger.set({\n    trpc: {\n      path: null,\n      type: null,\n      batched: true,\n      batch_size: updated.length,\n      procedures: updated.map((item) => `${item.type} ${item.path}`),\n    },\n  });\n}\n\nfunction isBatchedRequest(logger: Logger): boolean {\n  return (batchedProcedures.get(logger)?.length ?? 0) > 1;\n}\n\ntype ValidationIssue = { path: Array<string | number>; message: string };\n\n// TRPCError wraps input-validation failures in a ZodError cause whose message\n// is the full pretty-printed issue list — a multiline JSON blob that is hostile\n// to columnar stores and log search. Detect that shape so the event can carry\n// structured error.issues plus a short error.message instead.\nfunction zodValidationIssues(error: unknown): ValidationIssue[] | null {\n  if (error === null || typeof error !== \"object\") {\n    return null;\n  }\n  const cause = (error as { cause?: unknown }).cause;\n  if (cause === null || typeof cause !== \"object\") {\n    return null;\n  }\n  const issues = (cause as { issues?: unknown }).issues;\n  if (!Array.isArray(issues) || issues.length === 0) {\n    return null;\n  }\n  const mapped: ValidationIssue[] = [];\n  for (const issue of issues) {\n    if (issue === null || typeof issue !== \"object\") {\n      return null;\n    }\n    const { path, message } = issue as { path?: unknown; message?: unknown };\n    if (typeof message !== \"string\" || !Array.isArray(path)) {\n      return null;\n    }\n    mapped.push({\n      path: path.filter(\n        (segment): segment is string | number =>\n          typeof segment === \"string\" || typeof segment === \"number\",\n      ),\n      message,\n    });\n  }\n  return mapped;\n}\n\nfunction shortValidationMessage(issues: ValidationIssue[]): string {\n  const parts = issues\n    .slice(0, 3)\n    .map((issue) =>\n      issue.path.length > 0 ? `${issue.path.join(\".\")}: ${issue.message}` : issue.message,\n    );\n  const suffix = issues.length > 3 ? ` (+${issues.length - 3} more)` : \"\";\n  return `input validation failed: ${parts.join(\"; \")}${suffix}`;\n}\n\nfunction annotateTrpcError(\n  logger: Logger,\n  path: string,\n  type: TrpcProcedureType,\n  error: unknown,\n  includeHttp: boolean,\n): void {\n  const status = trpcErrorHttpStatus(error);\n  if (!logger.sealed) {\n    logger.error(error, { status });\n    const issues = zodValidationIssues(error);\n    if (issues) {\n      logger.set({ error: { message: shortValidationMessage(issues), issues } });\n    }\n    // On a batch, keep trpc.path null and record the failing procedure\n    // separately — overwriting the batch path with the failer made group-bys\n    // on trpc.path a half-truth.\n    const trpcPatch = isBatchedRequest(logger)\n      ? { failed_path: path, failed_type: type }\n      : { path, type };\n    const patch: Record<string, unknown> = {\n      trpc: trpcPatch,\n      status,\n    };\n    if (includeHttp) {\n      patch.http = { status };\n    }\n    logger.set(patch);\n  }\n}\n\nfunction finalizeStandaloneRequest(\n  logger: Logger,\n  path: string,\n  type: TrpcProcedureType,\n  result: unknown,\n): void {\n  if (logger.sealed) {\n    return;\n  }\n\n  if (isFailedMiddlewareResult(result)) {\n    annotateTrpcError(logger, path, type, result.error, false);\n  } else {\n    logger.set({\n      trpc: { path, type },\n      status: 200,\n    });\n  }\n\n  logger.emit();\n  scheduleFlush();\n}\n\nexport function amplioTrpcMiddleware() {\n  return async <TResult>(opts: {\n    path: string;\n    type: TrpcProcedureType;\n    next: () => Promise<TResult>;\n  } & Record<string, unknown>): Promise<TResult> => {\n    const { path, type, next } = opts;\n\n    if (hasAmbientLogger()) {\n      const logger = getLogger();\n      annotateTrpcProcedure(logger, path, type);\n\n      try {\n        const result = await next();\n        if (isFailedMiddlewareResult(result)) {\n          annotateTrpcError(logger, path, type, result.error, true);\n        }\n        return result;\n      } catch (error) {\n        annotateTrpcError(logger, path, type, error, true);\n        throw error;\n      }\n    }\n\n    const requestLogger = createLogger({\n      event: \"trpc.request\",\n      \"@event\": \"trpc.request\",\n      request_id: createRequestId(),\n      transport: \"server-caller\",\n    });\n\n    return runWithLogger(requestLogger, async () => {\n      annotateTrpcProcedure(requestLogger, path, type);\n\n      try {\n        const result = await next();\n        finalizeStandaloneRequest(requestLogger, path, type, result);\n        return result;\n      } catch (error) {\n        if (!requestLogger.sealed) {\n          annotateTrpcError(requestLogger, path, type, error, false);\n          requestLogger.emit();\n          scheduleFlush();\n        }\n        throw error;\n      }\n    });\n  };\n}\n"
    }
  ]
}