fix(build): externalize @galacean peers in miniprogram build instead of bundling

[cptbtptpbcptdtptp]

Fixes #349 on the dev/2.0 (2.0) line. Counterpart of #350 (which targets main/1.x).

dev/2.0 carries the identical miniprogram build defect, so the same fix is cherry-picked here: externalize each peer/dep at both its package name and /dist/miniprogram, and redirect only @galacean/engine (quote-agnostic). @galacean/engine-xr then stays external as require('@galacean/engine-xr') instead of being bundled (which inlined ~2MB of engine-xr + engine-math into dist/miniprogram.js).

See #349 / #350 for the full root-cause analysis and the rollup + rollup-plugin-modify verification.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Refined miniprogram Rollup configuration to improve dependency externalization and module redirection accuracy in builds.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: ed771db3-cabb-4a76-b1d9-2f5a10ddddb4

📥 Commits

Reviewing files that changed from the base of the PR and between f1be5d9 and 226be75.

📒 Files selected for processing (2)

• rollup.config.mjs
• rollup.miniprogram.plugin.mjs

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Walkthrough

Two Rollup build files are updated to fix miniprogram CJS output. rollup.config.mjs now externalizes each dependency at both its raw package name and its /dist/miniprogram path using flatMap. rollup.miniprogram.plugin.mjs narrows the import specifier redirect regex to match only @galacean/engine using a quote-anchored back-reference, preventing partial matches against peer packages like @galacean/engine-xr.

Changes

Miniprogram CJS externalization and specifier redirect fix

Layer / File(s)	Summary
Miniprogram plugin: narrowed specifier redirect regex rollup.miniprogram.plugin.mjs	Replaces the hardcoded regex covering @galacean/engine and @galacean/engine-xr with a quote-anchored back-reference pattern that matches only @galacean/engine, preventing partial matches against peer packages and preserving the original quote character in the rewritten specifier.
Rollup config: dual externalization per dependency rollup.config.mjs	Switches the miniprogram CJS external array construction from map to flatMap so each dependency/peer is externalized under both its raw package name and its /dist/miniprogram entry; adds comments describing the adapter redirection behavior.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• engine-toolkit-xr miniprogram build bundles engine-xr + engine-math (~2.5MB dist/miniprogram.js) #349: The changes directly implement the fix for the bundle-size regression described in this issue by addressing both root causes: externalizing each dependency at both its raw package name and /dist/miniprogram entry, and restricting the specifier redirect to @galacean/engine only with proper quote handling.

Poem

🐇 A bunny once tangled in regex despair,
/dist/miniprogram floating everywhere.
With flatMap and back-refs and quotes held tight,
The engine-xr ghost faded out of sight.
Now every extern finds its proper place,
And miniprogram builds at a bunny's pace! 🎉

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main fix: externalizing @galacean peers in miniprogram build instead of bundling them, which directly addresses the core issue described in the PR objectives.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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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/miniprogram-externalize-engine-xr-2.0

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