fix(bundler): check bun exists in PATH before compile

[zrosenbauer]

Summary

• Adds a bun --version check at the start of compile() to verify bun is available in PATH
• Returns a clear error message with install link when bun is missing instead of a cryptic ENOENT
• Adds test coverage for the missing-bun scenario and updates existing tests to account for the new check

Test plan

• pnpm typecheck passes
• pnpm lint passes (oxlint)
• pnpm format passes (oxfmt)
• pnpm test --filter=@kidd-cli/bundler — all 108 tests pass

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Project	Deployment	Actions	Updated (UTC)
oss-kidd	Error		Mar 24, 2026 6:40pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 6a0fbc5

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

This PR includes changesets to release 2 packages

Name	Type
@kidd-cli/bundler	Patch
@kidd-cli/cli	Patch

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[codspeed-hq]

Merging this PR will not alter performance

✅ 2 untouched benchmarks

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_{Comparing fix/bundler-check-bun-exists (6a0fbc5) with main (ea67f10)}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: de626e35-4a54-418d-a215-394476862cbb

📥 Commits

Reviewing files that changed from the base of the PR and between ea67f10 and 6a0fbc5.

⛔ Files ignored due to path filters (1)

• .changeset/check-bun-exists.md is excluded by !.changeset/**

📒 Files selected for processing (2)

• packages/bundler/src/compile/compile.test.ts
• packages/bundler/src/compile/compile.ts

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📝 Walkthrough

Walkthrough

The PR adds a preflight check to the compile() function that verifies bun availability by running bun --version before attempting compilation. A new private checkBunExists() function wraps this command and returns early with an error if bun is not installed. Corresponding test changes add a test case validating the error path and refactor existing tests to properly sequence multiple execFile mock implementations, since compile() now makes multiple invocations to execFile.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• kidd#96: Both PRs modify packages/bundler/src/compile/compile.ts and its tests to adjust bun invocation handling, including refactoring execFile call sequencing and error handling logic.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the primary change: adding a preflight check for bun existence before compilation.
Description check	✅ Passed	The description clearly relates to the changeset, outlining the bun availability check, error handling improvement, and test coverage additions.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/bundler-check-bun-exists

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