fix(web): render assistant images inline in chat

[t3dotgg]

Problem

When an agent viewed or produced an image, the chat timeline hid it twice. The tool row folded under the "Worked for ..." summary once the turn settled, and even unfolded, the image only appeared after the user clicked the row open. The agent thought it had shown a screenshot; the user saw nothing.

What changed

Rows that preview an image now render on their own. They stay out of tool groups, stay out of the settled-turn fold, and show the image without an expand click. This reuses the existing signed asset route, so no image bytes travel over the websocket.

The change is in apps/web, which desktop wraps. Mobile has a parallel work-log row and still gates its image behind expand; that is a separate fix.

Markdown images with local paths

Absolute paths and file:// URIs already resolve through the signed asset route after #9023, which introduced the media-file resource. The reporter tested a build from before that merge. I added a POSIX regression test for ![x](/tmp/embed-test/2.png) and ![x](file:///tmp/embed-test/5.png) because the existing coverage only exercised Windows path forms.

Still unsupported: data URIs

data: images in Markdown and in HTML <img> stay unsupported on purpose. Large base64 in a message is a performance problem twice over: it inflates every websocket frame that carries the message, and it inflates the DOM node that renders it. Agents should write the file and reference its path instead.

Provider coverage

Claude and the ACP providers (Cursor, Grok) are the only ones that put real image data on the wire. T3 Code does not carry those bytes through. It carries the file path and re-reads the file through the signed asset route, which is why this fix is a rendering change and not a contract change. Codex view_image and OpenCode only emit a label, no pixels, so path-based rendering is all they could ever support.

Tests

• apps/web/src/components/chat/MessagesTimeline.logic.test.ts covers the row placement: the command row folds, the image row stays visible and does not collapse into a tool group.
• apps/web/src/components/ChatMarkdown.workspace-images.test.tsx covers POSIX absolute and file:// sources resolving to a signed media-file asset.

vp test run on the touched files plus the neighboring work-log and markdown-image suites: 147 passed. Web typecheck and lint clean.

No before/after images. This was not run in a browser.

Refs #9094

Built by Claude Opus 5 in the Claude Code harness.

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Note

Low Risk
UI-only timeline and markdown rendering changes with broad test coverage; no auth, API, or data contract changes.

Overview
Image-preview work rows (agent viewed/produced screenshots) now stay visible in the chat timeline instead of folding into “Worked for …” or hiding behind tool groups and expand clicks.

Timeline derivation adds workEntryRendersImagePreview (via workEntryViewedImagePath) and threads it through group visibility, settled-turn folds, live activity grouping, and standalone row emission so image rows behave like first-class answers. MessagesTimeline.tsx renders ChatMarkdownAssetImage below the row header without requiring expand; tool output text remains behind expand.

Adds regression tests for POSIX/file:// markdown images resolving to signed media-file assets, plus timeline tests that image rows survive folding and in-progress turns.

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Note

Render assistant images inline in chat timeline work rows

• Adds workEntryRendersImagePreview predicate in MessagesTimeline.logic.ts to classify work entries with a viewed image path as image-preview rows.
• Updates workEntryIsVisibleInGroup, deriveTurnFolds, and deriveMessagesTimelineRows so image-preview entries pass the group-visibility filter, are excluded from settled-turn folds, and are emitted as standalone rows rather than absorbed into active or adjacent tool groups.
• Moves the viewed-image rendering in MessagesTimeline.tsx out of the expanded-detail container so it displays without expanding the row; expanding still controls the separate tool body.
• Adds tests covering POSIX/file-URI asset loading in ChatMarkdown.workspace-images.test.tsx and image-preview visibility in MessagesTimeline.logic.test.ts.
• Behavioral Change: work entries previously folded or grouped when neutral will now appear as visible image rows when they have a viewed image path.

^{Macroscope summarized 54b2d49.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.6 KiB	13.7 KiB	+134 B (+1.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	+6 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.6 KiB	6.7 KiB	+128 B (+1.9%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.1 KiB	58.5 KiB	+1.4 KiB (+2.5%)	66.4 KiB	✅
Codex	Live turn messages	10	10	0 (0.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.6 KiB	+55 B (+0.4%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.0 KiB	7.0 KiB	−6 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.6 KiB	+61 B (+0.9%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.8 KiB	57.9 KiB	+88 B (+0.1%)	66.4 KiB	✅
Claude	Live turn messages	8	10	+2 (+25.0%)	21	✅

Baseline: 4b26132 · PR result: 54b2d49 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 113.8 KiB
• Claude decoded thread snapshot: 114.5 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

Approvability

Verdict: Approved at 1a1d3b1

Macroscope's review found this PR approvable — This is a contained web chat rendering fix that keeps existing image-preview entries visible and renders them through the existing signed asset loader. Production changes are limited to timeline grouping and row presentation, with regression tests added and no schema, security, billing, default, or deployment changes.

No code changes detected at 54b2d49. Prior analysis still applies.

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[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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