fix(config): fail fast when config is missing in production builds

[PierreBrisorgueil]

Summary

• What changed: Extract config validation into src/lib/helpers/configGuard.js with assertConfigLoaded() that throws in production mode when the app config is still the placeholder. vite.config.js calls this guard inside defineConfig.
• Why: SEO plugins (seo-inject, prerender, seo-static) depend on real config values — a silent fallback in production leads to broken prerendering and missing SEO artifacts.
• Related issues: Closes fix(config): fail fast when config is missing in production builds #3669

Scope

• Modules impacted: src/lib/helpers (new helper), vite.config.js (import + call)
• 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
• Mergeability considerations: adds one new helper file and one test file; only a two-line change in vite.config.js
• Follow-up tasks (optional): none

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 72414b63-3fe8-4c16-a7db-95a45bfe31e2

📥 Commits

Reviewing files that changed from the base of the PR and between 0a50388 and 17ad89d.

📒 Files selected for processing (3)

• src/lib/helpers/configGuard.js
• src/lib/helpers/tests/configGuard.spec.js
• vite.config.js

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/config-fail-fast-production

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.12%. Comparing base (0a50388) to head (17ad89d).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3671      +/-   ##
==========================================
+ Coverage   91.03%   91.12%   +0.08%     
==========================================
  Files          21       22       +1     
  Lines         636      642       +6     
  Branches      170      173       +3     
==========================================
+ Hits          579      585       +6     
  Misses         57       57              

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[Copilot]

Pull request overview

This PR adds a fail-fast mechanism for production builds when the app config file (src/config/index.js) is missing or still a placeholder. Previously, the build would silently fall back to { port: 8080 }, causing SEO plugins (seo-inject, prerender, seo-static) to produce broken or missing artifacts. The new guard throws a clear error in production mode, directing developers to run npm run config first.

Changes:

• New configGuard.js helper exporting CONFIG_PLACEHOLDER and assertConfigLoaded() that throws in production when config hasn't been properly loaded
• vite.config.js updated to use CONFIG_PLACEHOLDER as the default and call assertConfigLoaded() inside defineConfig
• Comprehensive test suite for the guard covering placeholder detection, real config acceptance, and mode-based behavior

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/lib/helpers/configGuard.js	New helper: exports CONFIG_PLACEHOLDER constant and assertConfigLoaded() guard function
src/lib/helpers/tests/configGuard.spec.js	Vitest specs covering all key scenarios for the config guard
vite.config.js	Imports and integrates the config guard; uses CONFIG_PLACEHOLDER as the initial fallback