fix(fontless): prefer concrete fallbacks declared in css

[danielroe]

a bug of very long standing

Summary by CodeRabbit

• Bug Fixes
  • Font fallback selection prioritizes explicit override fallbacks, then combines concrete CSS-declared fallback families with category defaults without duplicates. Generic families and provider-reported categories are used when no concrete CSS fallbacks are provided.

[netlify]

✅ Deploy Preview for fontless ready!

Name	Link
🔨 Latest commit	d06c290
🔍 Latest deploy log	https://app.netlify.com/projects/fontless/deploys/6ab3f1d7a5c2ac000710760a
😎 Deploy Preview	https://deploy-preview-855--fontless.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: a8583b9f-5acd-4071-b059-c9bd233a10dd

📥 Commits

Reviewing files that changed from the base of the PR and between 25d3000 and d06c290.

📒 Files selected for processing (2)

• packages/fontless/src/resolve.ts
• packages/fontless/test/resolve.spec.ts

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

---

📝 Walkthrough

Walkthrough

Fallback resolution now combines CSS-declared concrete fallbacks with category defaults and removes duplicates. Explicit override fallbacks take precedence. Tests cover concrete fallback handling and precedence.

Changes

Fallback resolution

Layer / File(s)	Summary
Fallback precedence and validation packages/fontless/src/resolve.ts, packages/fontless/test/resolve.spec.ts	resolveFallbacks receives full fallback options and provider-reported fallbacks. It merges CSS-declared concrete fallbacks with category defaults and removes duplicates. Explicit override fallbacks take precedence.

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

Merge Risk: ⚪ Minimal · up to d06c2

The fallback change is mergeable after normal checks; no actionable issue remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	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 clearly and concisely describes the main change: preferring concrete fallbacks declared in CSS.
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.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/fontaine@855

npm i https://pkg.pr.new/fontless@855

commit: d06c290

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (6499534) to head (d06c290).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #855   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           17        17           
  Lines         1175      1178    +3     
  Branches       367       368    +1     
=========================================
+ Hits          1175      1178    +3     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[gioboa]

Nice 👍