[FEATURE]: Auto-collapse all completed response activity into one summary row in Desktop

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Describe the enhancement you want to request

Problem

In OpenCode Desktop, after an assistant response finishes, every process detail remains laid out above the final answer: reasoning, exploration, read, grep, glob, list, Shell, Webfetch, edit, write, patch calls, and other tool activity. Long turns can leave dozens of rows on screen, so the final answer is difficult to find and read.

Disabling Show reasoning summaries, Expand Shell tool calls, and Expand edit tool calls does not solve this. Those settings only affect reasoning text or the body of individual tool cards; the activity rows themselves remain visible.

This request is not just about collapsing reasoning text or each tool output separately. It is about one turn-level collapsible container that includes all activity before the final answer, regardless of activity type.

Desired behavior

Please match the interaction used by Codex Desktop:

• While the assistant is working, show reasoning and tool activity live.
• When the final answer appears, automatically collapse all preceding reasoning and tool activity for that turn into one compact summary row, for example: Completed in 3m 39s or Completed · 18 steps · 3m 39s.
• Keep the final answer outside the collapsed container and immediately readable.
• Clicking the summary row should expand the complete chronological activity history; clicking again should collapse it.
• If the user manually expands a completed turn, do not immediately auto-collapse it again.
• Ideally provide a setting such as Auto-collapse completed response activity, enabled by default.

The collapsed group should include every activity type, including reasoning, exploration groups, searches, reads, shell commands, web fetches, edits, writes, patches, and any future tool types.

Why this matters

The activity timeline is useful while work is in progress, but after completion the final answer becomes the primary content. Keeping all implementation details permanently flattened into the conversation creates visual noise, increases scrolling, and significantly hurts readability during long coding sessions.

Environment

• OpenCode Desktop 1.18.29
• Windows
• Current/new Desktop layout

Related issues

• #29212 requests collapsible reasoning/thinking text, but does not cover grouping the entire completed turn, including every tool activity type.
• #7174 describes the older steps panel auto-collapsing after completion, but its request was about persisting panel state across sessions. This request asks to restore that completed-turn behavior in the current Desktop layout and apply it to all activity.