perf: switch from esbuild to rolldown for babel build

[DylanPiercey]

No description provided.

[changeset-bot]

🦋 Changeset detected

Latest commit: f39ceff

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

This PR includes changesets to release 1 package

Name	Type
@marko/compiler	Patch

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[coderabbitai]

Walkthrough

This pull request introduces rolldown as a new build tool for bundling. Changes include adding rolldown as a devDependency in the root package.json, replacing the esbuild-based build-babel.ts script with a new rolldown-based bundle-babel.mts script in the compiler package, and updating the compiler's build script to invoke the new bundling script. Additionally, a new bundle.mts script is added to the runtime-tags package to manage multi-target builds across different environments and formats. A changeset documents the compiler package patch.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	No description was provided by the author, making it impossible to assess relevance to the changeset.	Add a brief description explaining the motivation for switching to rolldown and any expected benefits or performance improvements.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: switching the Babel build from esbuild to rolldown for performance improvements.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch use-rolldown-babel-build

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[coderabbitai]

Actionable comments posted: 3

🤖 Fix all issues with AI agents

In `@package.json`:
- Line 81: The dependency version for rolldown in package.json is using a caret
range ("^1.0.0-rc.3") which allows upgrades; change the version string for the
"rolldown" dependency to the exact pin "1.0.0-rc.3" (remove the caret) and then
reinstall/update lockfile (npm/yarn/pnpm) so the lockfile reflects the pinned
version; update any package manager lockfile accordingly.

In `@packages/compiler/package.json`:
- Line 66: The build script invokes node scripts/bundle-babel.mts which requires
Node 22.6+; to keep compatibility with the current "engines" range ("node": "18
|| 20 || >=22") modify the "build" script entry in package.json so it uses the
existing ~ts register (or an explicit Node flag) instead of relying on native
.mts stripping; update the "build" script string referenced as "build" to run
node -r ~ts scripts/bundle-babel.mts (or alternatively bump the "engines" field
to ">=22.6" if you want to require newer Node), ensuring you change the "build"
script and/or the "engines" value accordingly.

In `@packages/runtime-tags/scripts/bundle.mts`:
- Around line 36-74: The nested .map calls around the build(...) invocation do
not return the inner promises, so the async callbacks (the anonymous async
function that calls build) are never collected/ awaited; change the outer
.map/.map/.map chain to return the results (or use flatMap/flat and then wrap
with Promise.all) so that the Promise returned by each async callback is
included and awaited by Promise.all; specifically ensure the anonymous async
callback that calls build, the surrounding ["dom","html"].map and the top-level
["dist/debug","dist"].map all return their mapped values so Promise.all receives
the full array of build() promises.

🧹 Nitpick comments (1)

packages/runtime-tags/scripts/bundle.mts (1)

1-7: TODO noted for future optimization tracking.

The referenced issues (oxc-project/oxc#6073 and #15375) track optimizations needed before this can fully replace ./build.ts.

Would you like me to open an issue to track when these upstream optimizations land so the migration can be completed?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.01%. Comparing base (de87dba) to head (f39ceff).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3079   +/-   ##
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  Coverage   89.01%   89.01%           
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  Files         370      370           
  Lines       46705    46705           
  Branches     4155     4155           
=======================================
  Hits        41575    41575           
  Misses       5078     5078           
  Partials       52       52           

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