[backryun]

Part of #8484. One character. Clears all five diagnostics in src/lib/batches/dispatch.ts.

A declaration that was wrong about its own runtime

Type '(request: any, context: any) => Promise<any>' is not assignable to type 'BatchRouteHandler'.
  Target signature provides too few arguments. Expected 2 or more, but got 1.        ×5

withInjectionGuard() returns

return async function guardedHandler(request: any, context: any) {

with the second parameter required, so every route it wraps advertises arity 2. The batch dispatcher's handler type is (request: Request) => Promise<Response> | Response, and TS correctly refuses to assign a function that needs an argument the caller will never pass.

The interesting part is which side was wrong. dispatch.ts:48 already calls it with one argument:

return await handler(request);

and has been doing so in production. context is only forwarded on to the inner handler, where routes that do not read it receive undefined — which is exactly what one-argument invocation produces. So the parameter has always been optional in practice; the signature just did not say so.

-  return async function guardedHandler(request: any, context: any) {
+  return async function guardedHandler(request: any, context?: any) {

Widening BatchRouteHandler to take two parameters would have been the other option, but that fixes it at the consumer and leaves four other wrapped routes still misdescribing their own arity.

Verification

208 → 203, zero new errors, on a line-number-agnostic diff of the full tsc error set.

• npm run typecheck:core — clean
• eslint, check:file-size — clean
• 370/370 across the 43 affected suites (injection-guard, batch, embeddings, moderations)

Nothing executable changed — an optional marker has no runtime representation.

No test added — the path is the existing behaviour

Checking coverage of what the declaration now permits is standard for these slices, and here it is already thorough. embeddings-auth.test.ts (4 call sites) and embeddings-route-apikeymeta-6929.test.ts call POST(req) with a single argument straight through withInjectionGuard — precisely the arity this change legalises, exercised end-to-end and passing before and after.

Worth noting what is not covered: batch-processor.test.ts mocks dispatchBatchApiRequest, so the batch path never reaches a real guarded handler. That gap predates this change and is unaffected by it — the one-argument contract is proven by the route tests instead.

[diegosouzapw]

Hi @backryun — clean one-liner. Optional context removes the withInjectionGuard(() => x, undefined) antipattern at callsites.

Approved as merge-ready (★4). /merge-prs will pick it up.