fix(start-plugin-core): stop eclipsing user's rsbuild output.assetPrefix

[alexandre-marchina]

Fixes #7827.

Summary

This PR uses api.getRsbuildConfig('original') to detect real user intent, and only writes to the client environment when the user set output.assetPrefix or server.base. The server.base precedence path is preserved.

Summary by CodeRabbit

• New Features
  • Added support for explicitly configuring an asset prefix for client-side resources.
  • Supports automatic asset prefixing, relative paths, and complete URLs.
  • Preserves configured public base paths when no explicit asset prefix is provided.
  • Leaves default root-based configurations unchanged so platform defaults continue to apply.
• Bug Fixes
  • Prevented client asset prefix settings from being applied to server-rendered resources.

[coderabbitai]

📝 Walkthrough

Walkthrough

The Rsbuild environment planner now accepts an optional asset prefix, preserves explicit user configuration, avoids writing a default client override, and keeps the SSR asset prefix unset. Tests cover default, path, automatic, and URL values.

Changes

Asset prefix handling

Layer / File(s)	Summary
Client asset prefix derivation and validation packages/start-plugin-core/src/rsbuild/planning.ts, packages/start-plugin-core/tests/rsbuild/output-directory.test.ts	The planner selects explicit assetPrefix, non-default publicBase, or undefined for the client environment, while SSR remains unset; tests cover these cases.
Explicit configuration forwarding packages/start-plugin-core/src/rsbuild/plugin.ts	The plugin checks the original Rsbuild config and forwards assetPrefix to the planner only when it was explicitly configured.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: schiller-manuel

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes match issue #7827 by avoiding default client assetPrefix writes and forwarding explicit values with tests.
Out of Scope Changes check	✅ Passed	The PR stays focused on rsbuild assetPrefix handling and related tests.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: preserving the user's rsbuild output.assetPrefix instead of overriding it.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

packages/start-plugin-core/tests/rsbuild/output-directory.test.ts (1)

200-207: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Assert that assetPrefix is absent for all server environments.

The Rsbuild environment plan statically adds the base server environment and dynamically adds the ssr (provider) environment based on the configuration. You can optionally strengthen this test by asserting that neither of the server environments receives an assetPrefix.

♻️ Proposed refactor

   test('server environment never gets an assetPrefix', () => {
     const plan = createRsbuildEnvironmentPlan({
       ...baseOptions,
       assetPrefix: 'https://cdn.example.com/',
     })
     expect(plan.environments.ssr!.output?.assetPrefix).toBeUndefined()
+    expect(plan.environments.server!.output?.assetPrefix).toBeUndefined()
   })

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/start-plugin-core/tests/rsbuild/output-directory.test.ts` around
lines 200 - 207, Strengthen the server asset-prefix test around
createRsbuildEnvironmentPlan by asserting that assetPrefix is undefined for both
the statically added server environment and the dynamically configured ssr
environment. Keep the existing CDN input and assertions for non-server behavior
unchanged.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@packages/start-plugin-core/tests/rsbuild/output-directory.test.ts`:
- Around line 200-207: Strengthen the server asset-prefix test around
createRsbuildEnvironmentPlan by asserting that assetPrefix is undefined for both
the statically added server environment and the dynamically configured ssr
environment. Keep the existing CDN input and assertions for non-server behavior
unchanged.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: f94d03c3-2333-4b1f-8697-838aa3be5fab

📥 Commits

Reviewing files that changed from the base of the PR and between 0b178a7 and 087f2f0.

📒 Files selected for processing (3)

• packages/start-plugin-core/src/rsbuild/planning.ts
• packages/start-plugin-core/src/rsbuild/plugin.ts
• packages/start-plugin-core/tests/rsbuild/output-directory.test.ts

[LadyBluenotes]

We only review implementation PRs after the underlying issue has been reproduced, triaged, and the scope has been agreed with a maintainer. Please include a minimal reproduction in the PR and wait for maintainer confirmation before submitting a fix. I’m closing this PR for now; we can revisit it once the issue is confirmed