deepseek-harness/.agents/notes/archived/feature/2026-07-26-code-mode-trajectory-waterfall-spans.md

Agent Note: Code Mode sub-calls in the trajectory and waterfall views

Status: implemented Archived: 2026-07-28

English | 中文

Scope: the final PR of the Code Mode UI stack — sub-dispatch rendering in the two non-chat views. Chat nesting is owned by the sub-call rows note; the timing this consumes is the live-parallel note's start/settle pair.

Problem

Trajectory and waterfall still rendered a run_code turn as one opaque Tool cell / one node-count bar. The chat view got nested sub-rows in the earlier PRs, but the two analytical views — whose whole purpose is structure and timing — showed none of the sub-call structure and none of the per-sub-call wall time the dispatch pair now records. Waterfall sub-spans were deliberately deferred until that pair existed: a span without real timing would have been a lie.

Decision

Trajectory: subtool cells interleaved after their parent Tool cell. Waterfall: real-time sub-lanes under the owning turn row.

• Trajectory: the layout fold takes the snapshot's codeDispatches index; after each Tool cell whose callId has dispatches (assistant-block calls, orphan results, and running calls alike), it interleaves one subtool cell per sub-dispatch in start order — indexes stay sequential across the interleave. A settled sub-call's duration is its start/settle pair (durationSeconds(sub.time, sub.callTime)); a running one shows the em dash, exactly the native in-flight convention. The new cell kind wears a Sub tag (business tint) and a 28px indent so nesting reads at a glance.
• Waterfall: deriveSubSpans folds the dispatch index into per-turn lanes with REAL timing — each parent's dispatch window is first start → last settle, and every lane's offset/width is its fraction of that window, so parallel sub-calls (PR3) visibly overlap. Each lane carries a timing provenance tag: measured (pair observed), running (settle pending — extends to the window end at reduced opacity), or unknown (settle-only replay window, callTime: null — drawn hollow and titled "duration unknown", never a fabricated 0 ms). Lanes draw under the owning turn's bar row, scaled into a fixed lane budget.
• Both views read codeDispatches through the standard snapshot hook — no new wire data, no new stores; replay renders identically to live by construction.

Alternatives considered

Fold sub-calls into the turn-span node counts (weight the existing bars). Rejected: it hides exactly the structure this stack exists to show, and node-count weighting is already flagged as a stand-in (deviation ledger #3).

A dedicated sub-call panel instead of in-view nesting. Rejected: the stack's settled UX is nesting under the parent everywhere; a separate panel would diverge from chat and double the selection plumbing.

Defer waterfall lanes until the P-III duration-lane redesign. Rejected: the sub-lane timing is real today (the pair), and the fraction-of-window rendering is independent of whatever the turn-level lanes become; deferring would strand the stack's timing payoff.

Consequences

The waterfall carries the first REAL wall-time rendering in the client (turn bars remain node-count stand-ins — the contrast is deliberate and labeled by hover titles). Trajectory cell indexes now count sub-calls, so #N totals grow on Code Mode turns. Specs pin the interleave order and durations, the running em-dash arm, window fractions (offsets/widths), the running-lane extension, the unknown-timing (settle-only) lane, and the rendered lane under the turn row; the built-client Code Mode fixture snapshot additionally pins both tabs' assembled rendering (sub-cells with real +0.8s durations, measured lanes).