feat(wrangler): report startup profile summary

[apeacock1991]

Show key performance metrics in the output of wrangler check startup, notably:

• Bundle size
• Startup profile (with breakdown)

The latter can be extracted from the flamegraph, but it seems nice to just show them directly in the output vs have to fish. Adding bundle size as it's another key start up metric that can greatly affect start up speed.

I will raise a docs PR for this if it's deemed good/reasonable to merge

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because:

[changeset-bot]

🦋 Changeset detected

Latest commit: 4413408

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
wrangler	Minor
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-pool-workers	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[workers-devprod]

Codeowners approval required for this PR:

• ✅ @cloudflare/wrangler

Show detailed file reviewers

[ask-bonk]

devtools-protocol is a declared dependency and already imported elsewhere as a type-only import. Good.

Now let me consider the activeTime semantics once more with a real edge case. If the profile has NO idle samples but the worker was mostly idle, activeTime would be inflated. But that's inherent to CPU profiling. Not a bug.

Let me look at whether there's a division-by-zero or NaN risk when profile.nodes is empty or endTime/startTime are undefined. Protocol.Profiler.Profile guarantees startTime/endTime as numbers, nodes non-empty. Fine.

Let me verify the final concern about formatMicroseconds — the profile time units. V8/workerd CPU profiler timeDeltas and startTime/endTime are in microseconds. formatMicroseconds divides by 1000 → ms. Correct.

I've completed a thorough review. Let me summarize findings:

• Logic in summarizeStartupProfile: correct, well-tested.
• getBundleSize: correctly excludes source-maps and the string metadata field.
• analyseBundle backward compat: shallow-copy {...profile} preserves JSON serialization for existing consumers.
• Type changes: Protocol is a declared dependency.
• Units (microseconds→ms): correct.
• Minor: await cpuProfileResult at line 103 awaits an already-resolved value (harmless).

The only truly minor nit (redundant await) is not worth flagging as it's not a bug and doesn't affect behavior. There are no actionable logic bugs, security issues, backward-compat violations, or incorrect API behavior.

LGTM

github run

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

[github-actions]

⚠️ Issues found

• .changeset/vpc-networks-connect-tunnel.md labels the feature as experimental but does not explain how users can opt in. Please add a note on how users can enable or access this experimental feature.

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commit: 4413408

[dario-piotrowicz]

Regarding the docs I assume we want to update this page? https://developers.cloudflare.com/workers/wrangler/commands/workers/#check 🤔

[dario-piotrowicz]

Very Nice! 🤩

Approving although the docs still need to be updated I think?

PS: feel free to ignore the Vite plugin E2E failures, those are unrelated to this PR and we're looking into fixing them

[workers-devprod]

Codeowners reviews satisfied