fix(seo): puppeteer prerender Docker support + minor plugin fixes

[PierreBrisorgueil]

Summary

• What changed: Four targeted fixes for the SEO/prerender plugin stack: (1) Dockerfile installs Chromium so Puppeteer works in Alpine builds, (2) renderRoute() closes the page in a finally block to prevent resource leaks on errors, (3) seo-static plugin uses a function-based apply gated on command === 'build' && mode === 'production', (4) prerender test expectations use path.join() for cross-platform compatibility.
• Why: Puppeteer silently fails in Docker Alpine because there is no Chromium binary; a page leak can exhaust memory on large route lists; the seo-static plugin was emitting assets in non-production builds; hardcoded forward-slash paths in tests would fail on Windows.
• Related issues: Closes fix(seo): Puppeteer prerender fails in Docker + minor plugin fixes #3672, closes fix(prerender): Puppeteer fails silently in node:lts-alpine Docker builds #3665, closes fix(prerender): close Puppeteer page in finally block to prevent resource leaks #3666, closes fix(seo-static): gate on production mode, not just build command #3667, closes fix(prerender): normalize expected paths in tests for cross-platform compatibility #3668

Scope

• Modules impacted: src/lib/plugins (prerender, seo-static), Dockerfile
• Cross-module impact: none
• Risk level: low

Validation

• npm run lint
• npm run test:unit
• npm run build
• Manual checks done (if applicable)

Guardrails check

• No secrets or credentials introduced (.env*, secrets/**, keys, tokens)
• No risky rename/move of core stack paths
• Changes remain merge-friendly for downstream projects
• Tests added or updated when behavior changed

Notes for reviewers

• Security considerations: none — Chromium is added only to the build stage, not the production Nginx image
• Mergeability considerations: minimal diff, no path changes
• Follow-up tasks (optional): none

Summary by CodeRabbit

• New Features

  • Enabled pre-rendering capabilities during build with Chromium integration.

• Bug Fixes

  • Improved error handling and resource cleanup in pre-rendering to ensure proper page closure even when operations fail.

• Improvements

  • SEO optimization plugin now activates exclusively in production builds, avoiding unnecessary overhead in development environments.

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 07b534da-00e6-4aa9-b628-65148e29f114

📥 Commits

Reviewing files that changed from the base of the PR and between 508d52f and e611c47.

📒 Files selected for processing (1)

• src/lib/plugins/tests/prerender.spec.js

📝 Walkthrough

Walkthrough

These changes enhance Puppeteer pre-rendering by installing Chromium in the Docker build stage with environment variable configuration. The prerender plugin now ensures Puppeteer page cleanup via try/finally blocks. The seo-static plugin activation is gated to production builds only via a new apply function. Test expectations are updated for OS-aware path handling and the new plugin activation behavior.

Changes

Cohort / File(s)	Summary
Build & Dependency Configuration Dockerfile	Installs Chromium and configures Puppeteer environment variables (PUPPETEER_EXECUTABLE_PATH, PUPPETEER_SKIP_DOWNLOAD) in build stage to enable pre-rendering without runtime downloads.
Resource Management src/lib/plugins/prerender.js	Wraps renderRoute logic in try/finally block to guarantee Puppeteer page.close() executes on both success and failure paths, preventing resource leaks.
Plugin Activation Gating src/lib/plugins/seo-static.js	Replaces static apply property with dynamic apply(config, { command, mode }) function that returns true only for production build commands, preventing activation in development or serve modes.
Test Updates src/lib/plugins/tests/prerender.spec.js, src/lib/plugins/tests/seo-static.spec.js	Updates prerender test expectations to use path.join for cross-platform path normalization; updates seo-static tests to validate the new apply function's conditional activation logic.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related issues

• fix(seo-static): gate on production mode, not just build command #3667: Implements the same production-only gating for seo-static plugin via apply function conditional on command and mode.
• fix(prerender): close Puppeteer page in finally block to prevent resource leaks #3666: Modifies prerender.js renderRoute to ensure page.close() always executes via try/finally block.
• fix(seo): Puppeteer prerender fails in Docker + minor plugin fixes #3672: Addresses the identical set of fixes: Dockerfile Chromium setup, prerender resource cleanup, seo-static activation guard, and OS-aware test paths.
• fix(prerender): normalize expected paths in tests for cross-platform compatibility #3668: Implements the same test path normalization using path.join in prerender.spec.js for cross-platform compatibility.
• fix(prerender): Puppeteer fails silently in node:lts-alpine Docker builds #3665: Proposes the same Dockerfile Chromium and Puppeteer environment variable configuration for Alpine Linux.

Possibly related PRs

• feat(seo): add seo-static Vite plugin for robots.txt, sitemap.xml, manifest.json #3658: Modifies the same seo-static Vite plugin with an apply function that conditionally activates based on build context, directly overlapping with the plugin activation changes here.

Poem

🐰 Chromium bundled, pages freed with care,
A finally block—resources to share!
Production gates the seo machine so keen,
Cross-platform paths where slashes have been.
Pre-rendering's dance, now complete and fair! 🎨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main changes: Docker support for Puppeteer and minor plugin fixes, which aligns with the four targeted fixes (Dockerfile Chromium, page resource cleanup, production gating, and test path portability).
Description check	✅ Passed	The PR description fully addresses the required template sections with clear summaries, scope, validation status, guardrails checks, and reviewer notes. All critical information is present and well-organized.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/seo-prerender-docker-3672

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.40%. Comparing base (0a50388) to head (e611c47).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3673      +/-   ##
==========================================
+ Coverage   91.03%   96.40%   +5.36%     
==========================================
  Files          21       21              
  Lines         636      639       +3     
  Branches      170      171       +1     
==========================================
+ Hits          579      616      +37     
+ Misses         57       23      -34     

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[Copilot]

Pull request overview

This PR delivers four targeted fixes for the SEO/prerender plugin stack: Dockerfile Chromium support for Puppeteer, a resource leak fix in renderRoute(), a production-mode gate for the seo-static plugin, and cross-platform test path handling.

Changes:

• Dockerfile installs Chromium in the build stage so Puppeteer can pre-render routes during Docker-based builds
• renderRoute() now wraps page operations in try/finally to guarantee page.close() on errors, and seo-static plugin uses a function-based apply to gate on both command === 'build' and mode === 'production'
• Prerender test expectations use path.join() instead of hardcoded forward slashes for Windows compatibility

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
Dockerfile	Adds Chromium installation + Puppeteer env vars to the build stage
src/lib/plugins/prerender.js	Wraps renderRoute() body in try/finally to always close the page
src/lib/plugins/seo-static.js	Converts apply: 'build' to a function that also checks mode === 'production'; adds JSDoc to generateBundle
src/lib/plugins/tests/prerender.spec.js	Uses path.join() in expected values for cross-platform compatibility
src/lib/plugins/tests/seo-static.spec.js	Updates test to verify the new function-based apply behavior

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/lib/plugins/tests/prerender.spec.js`:
- Around line 95-98: The test in prerender.spec.js still compares
startsWith(distDir) using a POSIX literal which is Windows-sensitive; update the
assertion to normalize both the expected prefix and the result before checking
the prefix (e.g., use path.normalize or path.resolve) so the startsWith check
uses the same platform-normalized form; locate the test referencing
routeToOutputPath and replace the raw distDir prefix assertion with a normalized
comparison (normalize both result and distDir before calling startsWith or
compare with normalized join(distDir, 'etc')).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 9c7ae2b4-e250-41b6-b1cf-9a854310ae7c

📥 Commits

Reviewing files that changed from the base of the PR and between 0a50388 and 508d52f.

📒 Files selected for processing (5)

• Dockerfile
• src/lib/plugins/prerender.js
• src/lib/plugins/seo-static.js
• src/lib/plugins/tests/prerender.spec.js
• src/lib/plugins/tests/seo-static.spec.js