Collapse work details during final answer streaming

[AadiJo]

What Changed

• T3 Code now collapses the “worked for...” details as soon as the final answer starts streaming.
• Before, it waited until the answer was fully done before collapsing that section.
• This matches the behavior in the Codex desktop app more closely.

Why

When an agent is working, the timeline shows tool calls and progress updates. Once the final answer starts, those details should move out of the way immediately so the answer is easier to read.

The old behavior was based on the final message being finished. That was too late, and if the user was actively trying to read the message, it would be jarring as everything shifted upward.

UI Changes

This changes when the work-session section collapses during a streaming response.

Before: the work session stays open until the final answer finishes.

After: the work session collapses when the final answer starts streaming, like Codex desktop.

before_after.mov

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
Touches orchestration events, provider ingestion, and timeline folding logic; changes are additive (optional phase) but affect live streaming UX and message projection.

Overview
Adds an optional assistant message phase (commentary | final_answer) end-to-end so the chat timeline can tell commentary from the final answer.

Codex maps lifecycle item phase into runtime messagePhase; provider runtime ingestion caches phase per runtime item and message and attaches it to assistant delta commands. Orchestration (decider, projector, SQL projection) and the web store persist and merge phase on streaming updates.

UI: MessagesTimeline folds the active turn’s “worked for…” section as soon as any assistant message in that turn has phase === "final_answer", including while it is still streaming—instead of waiting for the turn to settle or streaming to finish.

^{Reviewed by Cursor Bugbot for commit a50270e. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Collapse work details during final answer streaming by propagating message phase end-to-end

• Introduces a phase field ('commentary' | 'final_answer') on messages across contracts, server orchestration, and client state, sourced from provider item lifecycle events in CodexAdapter.ts.
• The server ingestion pipeline in ProviderRuntimeIngestion.ts tracks phase per assistant message and includes it on thread.message.assistant.delta commands, which flow through the decider and projector into persisted thread state.
• On the client, MessagesTimeline.logic.ts adds deriveFinalAnswerStartedTurnIds and updates deriveTurnFolds to fold commentary/tool activity turns as soon as a final_answer-phase message starts streaming, without waiting for the turn to settle.
• Behavioral Change: turns with active work items now fold mid-stream once a final answer begins, changing the visible chat layout during streaming.

^{Macroscope summarized a50270e.}

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[cursor]

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

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[cursor]

Phase not persisted in projection

Medium Severity

The PR writes phase on thread.message-sent projection upserts, but the projection message schema, SQL row mapping, and snapshot hydration never define or read phase. After a reload or snapshot-based thread fetch, assistant messages lose final_answer, so deriveFinalAnswerStartedTurnIds cannot early-collapse work during streaming.

 

^{Reviewed by Cursor Bugbot for commit a50270e. Configure here.}

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces new user-facing behavior (collapsing work details during final answer streaming) across multiple system layers. An unresolved review comment identifies a medium-severity bug where the phase field isn't persisted, causing the feature to break after thread reload.

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