feat(brand): render the GitHub social preview from the luminary field

[hyperb1iss]

What this changes

The brand build gains a GitHub social preview output: github-social.png at 1280x640, the luminary nebula field with the triskelion mark over the glowing wordmark, the same composition the installer art already uses. One rendered copy is checked in at assets/brand/social/hypercolor-social.png so the image the repo settings page carries has a source of truth in git. The existing github-banner.png also stops clipping: it fit the horizontal lockup by height only, and that lockup is wider than 4:1, so it overran both edges.

Why

The repository has no social preview, so a link to it on Hacker News, Slack, or Mastodon renders as a plain text card. SilkCircuit ships a proper one; Hypercolor should walk in with the same energy.

Verification

• uv run assets/brand/build.py stage code executed against the checked-in masters through the module's build_social entry point; both outputs render at 1280x640 and were inspected visually (the checked-in PNG is that render).

• The brand README documents the new directory and the manual upload step. GitHub has no API for the social preview, so setting it is a one-time click under Settings, General, Social preview.

• Added or updated tests (not applicable; brand asset build)

• Added or updated docs (README, AGENTS.md, relevant spec, or guide)

• just verify passes locally (not applicable; no Rust changes)

• just deny passes (not applicable)

• just ui-test and just ui-build pass (not applicable)

• just sdk-lint, just sdk-check, and just sdk-build pass (not applicable)

• just python-verify passes (not applicable)

• just compat-check passes (not applicable)

• just docs-build passes (not applicable; brand README is not part of the site)

• cd docs && zola check passes (not applicable)

• Packaging scripts were syntax-checked (not applicable)

• just e2e-build passes with the normal Servo stack (not applicable)

• just e2e-build-cpu passes when validating the CPU smoke fallback (not applicable)

• just e2e passes against the Servo stack (not applicable)

• Tested on real hardware, simulator, or e2e harness (not applicable)

🤖 Generated with Claude Code

https://claude.ai/code/session_013dXbUNEe4yxrGhQLXbzRou

Summary by CodeRabbit

• New Features
  • Added a GitHub social preview image in a 1280×640 format, using the updated vertical brand composition.
• Bug Fixes
  • Improved organization banner fitting to prevent horizontal overflow while maintaining appropriate sizing.
• Documentation
  • Updated brand asset documentation to include the social preview image and its location in the asset directory.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: a46f33e1-2b58-48eb-92d1-6396e7672a10

📥 Commits

Reviewing files that changed from the base of the PR and between fff0a27 and 8de1179.

⛔ Files ignored due to path filters (1)

• assets/brand/social/hypercolor-social.png is excluded by !**/*.png

📒 Files selected for processing (2)

• assets/brand/README.md
• assets/brand/build.py

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The brand build now fits the GitHub banner by width, caps its height, and generates a 1280×640 social preview. The README documents the checked-in preview, upload location, and regeneration workflow.

Changes

Brand social preview

Layer / File(s)	Summary
Social asset generation assets/brand/build.py	build_social fits the GitHub banner by width, limits its height to 360 pixels, and generates github-social.png with _luminary_vertical.
Social asset documentation assets/brand/README.md	The README documents the social/ directory, the 1280×640 preview, its GitHub upload path, and the regeneration workflow.

Priority: ⬇️ Low

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

Change: Feature

Merge Risk: ⚪ Minimal · up to 8de11

The brand build and social preview asset are internally consistent, with no established merge-blocking risk.

🚥 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%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 …	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: generating the GitHub social preview from the luminary field. It matches the pull request objectives and changes.
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

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