deepseek-harness/.agents/notes/archived/feature/2026-07-23-trajectory-step-cell.md

Agent Note: Trajectory step cell and turn list chrome

Status: implemented Archived: 2026-07-26

English | 中文

Problem

The trajectory tab needs a reusable step row and turn-list chrome that can show expanded assistant blocks, own-duration times, Message token columns, and in-flight work. Without folding session event times into conversation nodes and expanding blocks into cells, the UI cannot match the product chrome.

Decision

@deepseek-ai/dsh-client-ui-trajectory owns the presentational trajectory list chrome:

• TrajectoryCell — 38px step row with kinds User / Message / Tool (no Think, Call, or Result rows). Reasoning blocks are skipped (no block-level clock). Each tool-call + paired tool-result folds into one Tool row (name · truncated args) whose Time is result.time − callTime when both are known. Message rows carry Input/Output/Think token columns from assistant.usage. Own-duration Time uses +Ns / +N.1s, or — when absent. Selected state draws a 2px inset --dsw-alias-brand-primary-new-colorprimary-new-color ring (selected prop) and is not wired to chat selection.
• TrajectoryTurn / header / group header — sticky Turn bar paints full-bleed ghost-active-fill; title/columns and the Message/Step body sit in a centered max-width: 880px lane. Cell trailing columns share the Turn header geometry (320 = 4×71 + 3×12); cells use pad 20/8.
• deriveTrajectoryLayout expands assistant blocks[] into cells, pairs tool-calls with tool-result by callId into Tool, folds partial and runningCalls (deduped), hangs usage on Message only (including the empty fallback when there is no text block), and builds group descriptions as wall-span + tool histogram (1.5s bash×6). user/message has no wire turn, so each User row is enclosed in the next assistant/steering turn, else the in-flight partial turn, else lastAssistantTurn + 1 (or 1). Context nodes emit no cell but still advance the Message duration cursor.

ConversationNode carries time from SessionEvent.time; ToolResultNode.callTime and RunningToolCall.time come from the paired tool/call. Duration rules: User +0s; Message = assistant.time − previous surface time (including skipped context); Tool = result.time − callTime when both known; in-flight Tool = —. Group header duration is earliest→latest absolute time in the group (wall span; Tool contributes start and start+duration).

Alternatives considered

Keep a Think cell for reasoning blocks. Rejected: a single assistant/message.time cannot yield Think own-duration without chunk-level clocks; omit the row rather than show —.

Keep separate Call and Result rows. Rejected: Result had no own duration to show; one Tool row carries the call→result interval.

Cumulative elapsed from session/turn start. Rejected; the Time column is each row's own duration.

Hang usage on the first expanded row. Rejected; usage attaches to Message only.

Show in-flight tool durations via Date.now(). Deferred; in-flight Time stays —.

Consequences

The Trajectory tab can render expanded finalized and in-flight rows with own-duration times once fold emits time. Behavior-shaped coverage lives in packages/client/ui-trajectory/tests/{cell,layout,views}.spec.tsx. Chat selection deep-links and finer block-level clocks remain deferred.