Prevent concurrent wrangler dev instances from fighting over the skills-install prompt

[dario-piotrowicz]

Fixes the concurrency bug described in #14116 (comment)

When two wrangler dev processes start in parallel, both could reach the interactive "Install Cloudflare skills?" prompt simultaneously. The second process's TTY output would overwrite the first's interactive prompt, making it invisible and unresponsive to the user.

A collision-detection mechanism now prevents this using the metadata JSONC file itself as a lock. Before showing the prompt, each process atomically creates the metadata file with a pending marker containing its PID and waits a 500 ms grace period. If a second process starts during that window, it overwrites the marker with its own PID and skips. The first process detects the PID change after the grace period and also skips. This ensures the prompt is only shown when a single wrangler dev instance is running. Stale pending markers (older than 60 seconds, e.g. from a crashed process) are automatically cleaned up.

---

• 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: self explanatory

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[changeset-bot]

🦋 Changeset detected

Latest commit: 818496c

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

This PR includes changesets to release 4 packages

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

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[github-actions]

✅ All changesets look good

[ask-bonk]

Review posted successfully to PR #14199 with a summary and two inline suggestion comments (fd leak fix + stale-marker liveness check), plus a ranked list of the three issues found.

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commit: 818496c

[workers-devprod]

Codeowners approval required for this PR:

• @cloudflare/wrangler

Show detailed file reviewers

• .changeset/fix-concurrent-skills-prompt.md: [@cloudflare/wrangler]
• packages/wrangler/src/tests/agents-skills-install.test.ts: [@cloudflare/wrangler]
• packages/wrangler/src/agents-skills-install.ts: [@cloudflare/wrangler]

[devin-ai-integration]

✅ Devin Review: No Issues Found

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

View in Devin Review to see 4 additional findings.

[petebacondarwin]

This feature is getting pretty complex! Is there some way we could simplify the whole approach? In my mind I feel like we could just say: the question is only ever shown once, whether or not it is answered. We can just write a "no" answer into the metadata file before we even ask the question; if the user decides to say yes, we overwrite it with a "yes". Then if a second Wrangler starts up while the first is showing the question, it will not ask the question since it thinks it has already been answered. This would also avoid the Ctrl-C problem too.