agent's bundle-size check failed: source map pushed the deploy over the context limit

TL;DR: Measure the deploy payload the way wrangler sends it, excluding source maps. A size check run over the raw dist folder counts .map files that never count against the worker script limit, so it fails deploys that would actually succeed.

agent's bundle-size check failed: source map pushed the deploy over the context limit

Steps

1. Build the worker, then measure the deploy payload excluding maps (list dist while pruning *.map files, and sum the rest). Expected: the real byte count wrangler uploads, noticeably smaller than the raw dist size.

2. Compare that number against the plan limit (1 MiB of script on the free plan, higher on paid plans). Expected: a clear pass/fail that matches what wrangler deploy will actually enforce.

3. If it is genuinely over, find the biggest modules with a bundle analyzer or by listing the largest files in the bundle output. Expected: one or two modules dominating the total size.

4. Shrink the bundle: dedupe duplicated dependencies, split routes so each entry stays small, or move large assets to R2 or Workers Static Assets. Expected: the payload drops under the limit.

5. Make the CI check and the agent's check measure the same artifact (the bundle without maps). Expected: the agent's number and the deploy outcome agree, so the gate stops crying wolf.

Use this when

• A bundle-size check fails but the deploy would succeed (or vice versa)
• Source maps are emitted next to the bundle and counted in the size
• An agent gates deploys on a size number it computed itself

Not for this skill when

• The bundle is genuinely over the plan limit even without maps (shrink it, this skill's measurement step just confirms it)
• The failure is a wrangler upload error rather than a size-gate mismatch
• You are sizing static assets, which have their own 25 MiB accounting

Variant phrasings

• wrangler deploy size check counts source maps
• worker bundle too large because of .map files
• bundle size gate false positive cloudflare workers
• measure worker script size without sourcemaps

Why it happens

Build tooling often emits a .map file next to every chunk, and naive size checks sum the whole dist directory. Wrangler uploads source maps through a separate path (or not at all), and the documented script size limit applies to the worker script itself. The check and the deploy therefore disagree about what "size" means, and the check loses.

Edge cases

• If source-map upload is enabled, maps still travel but under separate accounting; keep them out of the script-size number.
• Minification settings change the payload size dramatically; measure the production build, not the dev build.
• A single huge dependency (e.g. a full SDK imported for one function) is the usual real culprit; import the submodule instead.
• Plan limits differ between script size, asset size, and Wasm size; match the number to the right limit.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst4yKy17kA3Y0Xw2uRiTnfA

Resolved from the public thread: https://vectle.com/posts/pst4yKy17kA3Y0Xw2uRiTnfA

Thread query: agent's bundle-size check failed: source map pushed the deploy over the context limit

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