feat(server): report image dimensions with signed asset URLs

[leoisadev1]

Problem

Chat images reserved a 16:9 slot, then jumped to their natural size after decode. That resize moves every row below the image.

Fix

Signed asset URLs now include optional imageDimensions read from PNG, JPEG, GIF, and WebP headers. Live bot and group markdown apply that size as soon as the URL resolves. JPEG honours EXIF orientation 5–8.

Adaptation

Reviewed port of pingdotgg/t3code#10198 and #10200. Akeru does not yet have host media-file resources; dimensions are read from existing workspace-file and attachment paths. Native mobile slot sizing (pingdotgg#10199) is later work. Expanded-image zoom/pan remains with the web-chat worker.

Scope

Additive image metadata and live ChatMarkdown slot sizing on bot and group chat routes. Video streaming, native previews, and preview recording transfers are separate.

Verification

Head 68804d0e40bfe4c961a763c5fdfcf3d34990298b on feat/asset-image-dimensions. Isolated home /tmp/akeru-ui.7d51ZM (populated fixture + workspace/shot.png 240×480). Server/web from vp run dev --home-dir /tmp/akeru-ui.7d51ZM ([dev-runner] serverPort=15008 webPort=6968). Paired agent-browser session image-layout2-f780f086c461 on /bots/ui-scout. Direct projection_thread_messages seed is a visual fixture, not command-path proof.

Focused tests:

• vp test run on packages/shared/src/imageDimensions.test.ts, apps/server/src/assets/AssetAccess.test.ts, and apps/web/src/components/ChatMarkdown.workspace-images.test.tsx: 29 passed.
• Typecheck for shared, contracts, server, and web exited 0.
• Targeted lint reported no new errors.

Browser (this agent, isolated client):

• Desktop 1280×800 on /bots/ui-scout: live <img alt="portrait"> box 240×480, computed aspect-ratio: 240 / 480, inline width: 240px. A 16:9 slot at width 240 would be 135px tall. Signed src was /api/assets/.../shot.png.
• Reserved slot without decoded pixels: clearing src dropped naturalWidth/Height to 0×0; the box stayed 240×480 with aspect-ratio: 240 / 480 (heightHeld: true). This is after signed-URL success, not during the loading placeholder.
• Mobile web viewport 390×844: same box 240×480, ratio 0.5, aspect-ratio: 240 / 480.
• Error path: pointing the live <img> at /api/assets/missing-fixture.png replaced it with Image unavailable · portrait and left no remaining <img>. Reload restored the 240×480 portrait.
• Loading placeholder is still aspect-video (16:9) until createUrl succeeds. The live loading-to-success jump was not captured; URL state was already Success when measured.

Not verified (blockers, not claimed):

• Group chat image layout. projection_groups count is 0 in this fixture. /groups/missing rendered no group conversation, so GroupThreadLanding ChatMarkdown was not measured. Same component as bot chat; live group route still unproven.
• Landscape image. Only the 240×480 portrait fixture was measured. Greptile/T-Rex landscape numbers are not this pass.
• Native mobile slot sizing (fix(mobile): size a chat image's frame before its bytes arrive pingdotgg/t3code#10199). Not in this PR. Host is Linux; no iOS/Android client was run.
• File preview panel. FilePreviewPanel also mounts ChatMarkdown; that route was not opened.
• createUrl Failure for a missing workspace path was unit-tested, not live-seeded. The live error case was the <img onError> fallback.

gh-attach is not installed on this host (gh 2.100.0 has no --attach). Screenshots stay in /tmp/akeru-pr-226-evidence/ (desktop-portrait-scrolled.png, mobile-portrait.png, mobile-error-fallback.png) and were not uploaded.

Limitations

• No media-file host-path resource yet.
• Mobile ThreadMarkdownImage frame sizing (fix(mobile): size a chat image's frame before its bytes arrive pingdotgg/t3code#10199) is not in this PR.
• Loading placeholder remains 16:9 until the signed URL (and dimensions) resolve.

Implemented with Grok 4.6 High in Grok Build via Orca.

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Project	Deployment	Actions	Updated
akeru-bot-landing	Ready	Preview	Sep 10, 2026 5:58pm UTC

[greptile-apps]

Greptile Summary

This PR adds bounded image-header dimension parsing, returns optional dimensions with signed asset URLs, and uses those dimensions to reserve proportional workspace-image space in chat markdown. No actionable issues were identified.

Confidence Score: 5/5

Safe to merge.

There are no outstanding findings.

Files Needing Attention: None.

_{Reviews (2): Last reviewed commit: "Merge branch 'main' into feat/asset-imag..." | Re-trigger Greptile}