feat: add ability to see live output of commands

[sethigeet]

I know this is not exactly a small PR, but its not really that huge and most of the stuff is boilerplate + tests and there aren't a lot of complicated changes.

What Changed

The tool calls are shown in the UI when they start (this is especially useful for seeing that the model ran a command like running tests or benchmarks which can take significant time and the user is not stuck seeing "working...") and the output of the terminal commands are streamed into the UI (just kept in memory for the current session, not persisted, just like the Codex App) so that the user can see what's happening

Why

• It's useful to see what the model is running as soon as it starts running it (rather than after it completes running it) so that we can stop it if its doing something wrong (for example, it might not be using something from our build system by default due to it not being mentioned in the Agents.md (or equivalent) and we can stop the model and ask it to change).
• Its also useful to see the outputs of the commands that the agent has run due to obvious reasons!

UI Changes

A "Show Output" button is added for the commands:

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

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Note

Medium Risk
Adds a new WebSocket stream carrying provider runtime command_output deltas and threads it through client state and work-log collapsing logic; correctness depends on stable itemId correlation and lifecycle grouping, and mistakes could cause confusing/incorrect work-log rendering or memory growth.

Overview
Adds live, ephemeral command output streaming from server to web UI via a new WS RPC subscription subscribeProviderRuntimeToolOutputEvents that forwards provider content.delta events where streamKind is command_output.

On the client, introduces runtimeToolOutputStore (per-thread/per-itemId buffer with a 24k char cap) and wires it into the root websocket event loop, clearing output on thread.deleted and thread.turn-start-requested. deriveWorkLogEntries is extended to keep relevant tool.started rows, correlate tool lifecycle rows using itemId/group keys, and inject buffered output into the matching work-log entry.

Updates the timeline UI to show a “Show output/Hide output” toggle (collapsed by default) for tool work entries with output, and expands server ingestion tool activities to include itemId and data for started/updated/completed events while ensuring command_output deltas are not persisted as activities (new tests cover these behaviors).

^{Written by Cursor Bugbot for commit ae5d9cd. This will update automatically on new commits. Configure here.}

Note

Add live command output streaming to the chat work log

• Adds a new WebSocket stream (subscribeProviderRuntimeToolOutputEvents) that emits content.delta events with streamKind: 'command_output' from the server.
• Introduces a Zustand store (runtimeToolOutputStore.ts) that buffers command output per thread and itemId, capped at 24,000 characters, and clears on turn start or thread deletion.
• Extends deriveWorkLogEntries in session-logic.ts to include tool.started entries for command/file-change tools and merge live output into work log entries via itemId correlation.
• Adds a collapsible 'Show output'/'Hide output' toggle to tool work entries in MessagesTimeline.tsx; output is collapsed by default.
• Reworks collapseDerivedWorkLogEntries to handle multiple concurrent commands using groupKey and itemId, reducing duplicate rows in the work log.

^{Macroscope summarized ae5d9cd.}

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[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a significant new feature for streaming live command output to the UI, including new state management, WebSocket subscriptions, and substantial logic changes. Additionally, an open review comment identifies a performance issue with excessive recomputation during streaming.

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[cursor]

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

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[cursor]

Excessive recomputation of work log on every streaming delta

Medium Severity

The runtimeToolOutputByItemIdRaw Zustand selector returns a new object reference on every appendOutput call (due to immutable spreads in the store). This causes runtimeToolOutputByItemId to create a new Map on every delta, which in turn forces deriveWorkLogEntries to fully recompute — sorting, filtering, and collapsing all activities — on every streaming output chunk. During active command execution with frequent output, this can cause significant unnecessary work.