fix(web): fall back when pull request avatars fail

[tastelessjolt]

Closes #11727.

What Changed

PullRequestActorAvatar now switches to the existing actor-initial fallback when a remote image emits an error. A focused regression test covers the failed-image path.

This is the first-stage fallback only. It does not proxy authenticated GHES avatar bytes or change GHES cookie behavior.

Why

Private GitHub Enterprise Server avatar URLs can be cross-site relative to the T3 client. When the browser withholds SameSite=Lax or SameSite=Strict authentication cookies, GHES refuses the image request. The URL is still non-null, so the previous component left a broken image in every pull request activity row.

Before	After
Broken images remain in the timeline.	Failed images fall back to actor initials.

Verification

• vp test run apps/web/src/components/pullRequest/pullRequestPresentation.test.tsx
• vp lint apps/web/src/components/pullRequest/pullRequestPresentation.tsx apps/web/src/components/pullRequest/pullRequestPresentation.test.tsx
• vp fmt --check apps/web/src/components/pullRequest/pullRequestPresentation.tsx apps/web/src/components/pullRequest/pullRequestPresentation.test.tsx
• vpr --filter @t3tools/web typecheck
• Captured matched before/after images from the real web component with deliberately unavailable GHES-style avatar URLs.

The shared web component covers hosted web, local web, remote connections, and desktop. Mobile has no corresponding pull request activity view. No provider or wire-contract changes are needed.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for the UI change
• Video is not applicable because this change has no motion or interaction

Created with GPT-5.6 Sol in the Codex harness.

Summary by CodeRabbit

• Bug Fixes

  • Pull request actor avatars now display an initial-based placeholder when the avatar image cannot be loaded.

• Tests

  • Added coverage for the avatar fallback behavior when remote images fail.

[macroscopeapp]

Approvability

Verdict: Approved at 847a43f

Macroscope's review found this PR approvable — This is a localized web bug fix that replaces failed pull-request avatar images with the component's existing actor-initial fallback. Existing avatar and null-avatar paths are preserved, and the new behavior is covered by a focused test.

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[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 8ef478e and 847a43f.

📒 Files selected for processing (2)

• apps/web/src/components/pullRequest/pullRequestPresentation.test.tsx
• apps/web/src/components/pullRequest/pullRequestPresentation.tsx

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📝 Walkthrough

Walkthrough

PullRequestActorAvatar now replaces failed avatar images with actor initials. A test covers the image error path and verifies the fallback output.

Changes

Avatar fallback

Layer / File(s)	Summary
Failed avatar fallback apps/web/src/components/pullRequest/pullRequestPresentation.tsx	The component tracks avatar load failures and renders the actor-initial placeholder when the avatar URL is missing or fails.
Fallback regression test apps/web/src/components/pullRequest/pullRequestPresentation.test.tsx	The test triggers the image error handler and verifies that the broken image is removed and the actor initial is rendered.

Priority: ⬇️ Low

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

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: maria-rcks

Merge Risk: ⚪ Minimal · up to 847a4

The avatar fallback is narrowly scoped and includes regression coverage for failed image loads.

🚥 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 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a fallback when pull request avatar images fail to load.
Description check	✅ Passed	The description is complete and focused. It explains what changed, why the change is needed, the UI impact, verification steps, screenshots, scope limits, and checklist status.
Linked Issues check	✅ Passed	Issue #11727 requires the existing actor-initial fallback when a non-null avatar URL fails. PullRequestActorAvatar now tracks failedAvatarUrl and renders the fallback when the failed URL matches t…
Out of Scope Changes check	✅ Passed	The changes are limited to PullRequestActorAvatar and its focused regression test. They implement the linked issue without provider, wire-contract, cookie, or mobile changes.

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