fix(web): media preview centers its content and pins the close button

[maria-rcks]

The media preview anchored its close button to the media wrapper, and that wrapper grew to fit the caption. A narrow image with a long file name sat on the wrapper's left edge, and the close button jumped to wherever the caption ended, so it moved between every image in a gallery.

The dialog is now a fixed stage. The media centers inside it, and the close button sits in the stage's top-right corner, so it stays in the same spot for every image, video, and zoom level. On narrow screens the prev/next buttons move from below the stage to its bottom corners, and the caption is padded so it stays clear of them.

Before, tall image with a long name: image sits left, close button floats mid-screen

After: image centered, close button in the corner

Before, next image in the same gallery: close button jumps right

After: close button stays put

On a 390px phone the caption keeps clear of the bottom arrows:

Verified in the web dev server with two composer attachments: arrow-key navigation, click-to-zoom, close button, clicking the empty stage to close, light and dark, and a 390px viewport. Lint, format, ExpandedImagePreview.test.ts, and web typecheck pass. Desktop and mobile apps are unaffected (desktop wraps this web dialog; mobile has its own viewer).

Opus 5.5 via Claude Code in T3 Code

[macroscopeapp]

Approvability

Verdict: Approved at 4142c7a

Macroscope's review found this PR approvable — This is a focused, single-file UI fix that centers existing media content, stabilizes the close button, and improves mobile navigation placement. Its runtime impact is limited to the existing preview's layout and controls, with no product-default, schema, security, or infrastructure changes.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 19251ba and 4142c7a.

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📒 Files selected for processing (1)

• apps/web/src/components/chat/ExpandedImageDialog.tsx

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🚧 Files skipped from review as they are similar to previous changes (1)

• apps/web/src/components/chat/ExpandedImageDialog.tsx

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📝 Walkthrough

📝 Walkthrough

Walkthrough

The expanded image dialog fills and centers its stage. The close button sits at the stage’s top-right. On small screens, navigation buttons sit at the stage’s bottom, and the caption gains horizontal padding. Navigation button positioning remains unchanged at sm and larger.

Changes

Expanded image dialog layout

Layer / File(s)	Summary
Stage and control layout apps/web/src/components/chat/ExpandedImageDialog.tsx	The stage fills its available height and centers content. The media wrapper fills the stage height. The close button moves to the stage’s top-right. On small screens, navigation buttons move to the stage’s bottom and the caption gains horizontal padding. Navigation positioning at sm and larger remains unchanged.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

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Merge Risk: ⚪ Minimal · up to 4142c

The preview layout has no newly identified issue that should prevent merging after normal checks.

Pre-merge checks | 3 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check		The description clearly explains the problem, the implementation, and the verification performed. It includes before-and-after screenshots and agent attribution. It does not provide the required scope…	Add a Scope and approval section. Link the triaged issue or maintainer-approved discussion, or explain why this small, focused fix qualifies as an obvious-bug exemption.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the main layout fix: centering media content and pinning the close button.

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Full details: Description check

Explanation

The description clearly explains the problem, the implementation, and the verification performed. It includes before-and-after screenshots and agent attribution. It does not provide the required scope and approval information or explain why this focused fix qualifies for an exemption.

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
Review comments at @apps/web/src/components/chat/ExpandedImageDialog.tsx:
- Around line 192-217: Add horizontal padding to the caption row in
ExpandedImageDialog so long filenames and caption actions stay clear of the
bottom navigation buttons’ hitboxes. Keep the change scoped to the caption row
and preserve the existing layout and navigation behavior.

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⚙️ Run configuration

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📥 Commits

Reviewing files that changed from the base of the PR and between 5f7294d and 19251ba.

📒 Files selected for processing (1)

• apps/web/src/components/chat/ExpandedImageDialog.tsx

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Dismissing prior approval to re-evaluate 4142c7a