fix: Node.js 24 compatibility — replace callback handlers with async return#111
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… compatibility AWS Lambda Node.js 24 runtime removed support for callback-based function handlers (Runtime.CallbackHandlerDeprecated). Both s3-handler and ag-handler were async functions still using the deprecated callback(null, response) pattern. Converted to return the response object directly. Updated all unit tests accordingly; also fixed a pre-existing silent test bug where the "directory" fixture key had no trailing slash and assertions inside callbacks were silently swallowed by mocha. Fixes #110
Two complementary checks to prevent #110 from recurring: 1. Unit-test arity assertion. Each handler test asserts `handler.length <= 2`, which is what AWS Lambda's runtime client checks (`errorOnDeprecatedCallback`) before deciding whether to reject async-with-callback handlers. Cheap, runs on every Node version in the existing matrix. 2. Runtime init smoke job. New CI job spins up each handler inside the official `public.ecr.aws/lambda/nodejs:24` image (with the Runtime Interface Emulator bundled) and POSTs an invocation. The handler's own assertions on the empty event are expected to fail — we only fail CI if the response contains a `Runtime.*` errorType (CallbackHandlerDeprecated, ImportModuleError, MalformedHandlerName, etc.), which means init itself broke. Verified locally against a synthetic callback-shaped handler: detected.
scanii-lambda only ever runs on the Linux Lambda runtime — testing on windows and macos was burning runner minutes for no signal.
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Summary
lib/s3-handler.jsandlib/ag-handler.jswereasyncfunctions that still calledcallback(null, response)— the pattern AWS Lambda Node.js 24 removed (Runtime.CallbackHandlerDeprecated)async (event, context) => { return response }— the only supported pattern in Node.js 24+const result = await handler(event, {})and assert on the returned value/so the directory check never triggered; assertions inside the old callback were silently swallowed by mocha, masking the broken testRegression guards (so this doesn't happen again)
handler.length <= 2, matching what AWS's runtime client checks. Cheap, runs on every Node version in the existing matrix.public.ecr.aws/lambda/nodejs:24(Runtime Interface Emulator bundled) and POSTs an invocation. We only fail onRuntime.*errorType in the response (CallbackHandlerDeprecated,ImportModuleError,MalformedHandlerName, …) — handler-side errors from the empty event are expected. Verified locally against a synthetic callback-shaped handler: detected.Test plan
npm test— passing locally (34 unit tests + 4 integration pending without local scanii-cli)setup-cli-actionLambda Node 24 runtime init smokejob exercises real runtime initFixes #110