feat(desktop): improve tool output rendering and interaction

[colaforniaw]

Summary

A long turn renders as a wall of tool rows, and opening one rarely helps: every tool shares the same generic detail — raw invocation lines, unstructured dumps, and for results the runtime has archived, a bare [archived_tool_result] tag with nothing behind it.

This PR rebuilds the desktop tool transcript around reading: collapsed rows state the action, target, and result count; large results render as bounded, structured previews; and whatever the preview omits stays reachable through an explicit, sha256-verified "Open full output" in the Files pane.

Current state

• Every tool renders through the same generic detail, so expanding a row yields invocation noise regardless of what the tool did.
• Results too large to keep inline are archived by the runtime; the desktop renders the placeholder as a bare [archived_tool_result] tag, so a growing share of tool output has no reader-facing path at all.
• Large text, JSON, and diff results dominate the conversation, and WebFetch lands as page-sized text instead of a source reference.
• During streaming, terminal output follows the tail and drags the viewport back when the reader scrolls away.

Implementation approach

• Add semantic tool summaries for file operations, search results, and success receipts so collapsed rows communicate the action and outcome directly.
• Use bounded, redacted previews for text, JSON, diffs, and shell output. Preserve complete retained results behind an explicit “View saved output” action in the Files panel.
• Render successful WebFetch results as compact citation cards with the title, source link, byte count, line count, and truncation state; keep failed fetches readable as text errors.
• Introduce a reusable output scroller that pauses tail-following when the user scrolls away and provides a “Jump to bottom” action to resume it.
• Transfer archived output through validated, chunked Host reads with bounded caching, while preserving existing storage and permission behavior.

Before / After

1. Collapsed tool rows: invocation lines to semantic targets

Before	After

Collapsed rows lead with the file, target, or result count instead of the raw invocation line, and surface result counts next to the row.

2. WebFetch: page-sized text to a citation card

Before	After

A compact citation replaces the page body. Users visit the source through its external link instead of expanding the body in the conversation.

3. Retained results: unreachable to inspectable

Before	After

Results omitted from the preview — including archived ones, which previously rendered as an invocation echo with no path to the body — can now be inspected and copied from the Files panel.

4. A full tool turn, expanded: dumps to bounded previews

Before	After

Expanding several completed tools stacks page-sized text walls and raw dumps. Each detail becomes a bounded, structured preview, with retained output reachable on demand.

Close #4863

Verification

• Targeted Core, UI interaction, Desktop IPC/client, and Runtime Host checks passed.
• Desktop builds and workspace typechecking passed.
• Staged Biome, ASF header, protocol epoch, and whitespace checks passed.

Full repository lint, format, build, test, and Desktop/UI Knip checks are not confirmed by the recorded validation. Real-window visual verification remains pending.

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: OpenAI Codex contributed implementation, regression tests, review-feedback analysis, local verification, and this PR description. The commit includes Generated-by: OpenAI Codex; retain it in the squash commit.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[Astro-Han]

Thanks for improving the tool-output reading experience! We reviewed 4338172 and left one small functional issue inline, plus a non-blocking request to measure the long-text rendering path. The Write issue was checked against the base version; the text-rendering note is a measurement suggestion, not a confirmed performance regression.

Separately, the current CI test job reports three unused exports in the Desktop story barrel; the Windows packaging check has passed.

This review was assisted by OpenAI Codex, including independent reviewer passes. The maintainer has confirmed the visual direction; the code findings and checks above are AI-assisted verification.

[Astro-Han]

[P2] Keep the full destination path inspectable for Write results

Could we retain a detail view for file_write results? This is a normal Write outcome when the runtime does not return a diff (for example, a 70,000-byte write). The collapsed row now shows only the basename, and treating this result as a status-only receipt disables its disclosure, so a write to /repo/packages/backend/config.json leaves no way to inspect the full destination from the tool row. This makes same-named files difficult to distinguish. I compared the same result against the base: the full path and disclosure were present there, and both are absent here. Keeping the compact basename while preserving the full path in the existing detail view would address it.

[Astro-Han]

Non-blocking: could we measure the long-text path?

This now passes the complete text through ToolTextPreview to CodeBlock, whereas the previous path capped it at 500 lines. The 208px height limit bounds the visible area, but the complete text still reaches the renderer. I have not reproduced a slowdown, so this is a request for validation rather than a confirmed regression. Could we compare base and head with a representative large retained text result (including many short lines), checking expansion time and responsiveness while scrolling? If the cost is material, we could keep a bounded inline preview and use the existing saved-output viewer for the full text; if the measurements are healthy, recording them would be sufficient.