Overview

What actually merged in Creative Agent Studio (the diffs chat pipeline) today was six commits fixing the live gate marker. While the multi-agent pipeline advances through its gate stages, the feed UI was showing “which gate is in progress” a beat too late — I chased that to the root and fixed it. Two more threads are in flight: an export-pipeline R&D (turning planning reports and storyboards into pptx/pdf — on the working tree, not yet committed) and a Firebase auth feature parked on a separate branch.

Previous: #5 — Observability & UX Patterns

Live Gate Marker: a UI Running a Beat Behind

Background

The pipeline advances through GATE 1–5, and the backend streams task_update and gate_emit events over SSE. The feed’s TaskUpdateNote component reads these to render a marker for “the gate currently in progress.” But a screenshot caught the bug: while Gate 5 (storyboard) was generating, Gate 4 kept showing as ready.

graph LR
    BE["Backend SSE"] -->|"task_update / gate_emit"| DISPATCH["dispatch-sse.ts"]
    DISPATCH -->|"resolve sessionId"| STORE["zustand store"]
    STORE --> NOTE["TaskUpdateNote (computes liveGate)"]
    NOTE --> UI["Feed gate marker"]

Fix 1 — sessionId drift

The display logic itself was correct; the inputs were not. The culprit was one line, dispatch-sse.ts:128:

// before
const sessionId = opts.sessionId ?? store.activeSessionId ?? undefined

When opts.sessionId is undefined and store.activeSessionId flips from null to a real id between two emissions, the marker id changes mid-stream — drift. Tracing it to the bottom: right after addSession, selectSession(created.id) runs synchronously, so activeSessionId is set immediately. That means once a session exists, every subsequent submit captures the real id, and only the very first stream started in the instant before session creation captures undefined. So the bug only fires in the split-second after a brand-new session is created — loaded past sessions are never affected.

The fix was a one-liner: drop the fallback entirely.

// after — remove the activeSessionId fallback
const sessionId = opts.sessionId ?? undefined

I wrote a regression test (dispatch-sse-storyboard.test.ts) that reproduced the scenario first, then fixed it. Full suite: 79 files / 489 tests pass, typecheck clean.

Fix 2 — liveGate lagging a beat

Even after that fix, the screenshot still showed Gate 4 as ready while Gate 5 generated. Tracing it surfaced the real gap: during storyboard generation the final gate_emit hasn’t fired yet, and session.gate/project.gate are still stuck at 4 (the scenario-approval value). So my liveGate = max(gate_emit values) never reached 5, and Gate 4 never advanced. In short, liveGate was running a beat behind.

The fix: once a Gate 5 (storyboard) task_update marker exists, read the Gate 4 marker as “Done” even with no final gate_emit and the gate stuck at 4. I added regression tests for that exact scenario (live-gate-marker-regression.test.tsx, FeedItem.test.tsx), and also hardened use-chat-stream.ts and the workspace slice to finalize lingering agents when the stream ends at a gate.

In Flight: Export Pipeline (Typst over LibreOffice)

The longest session today (~2.5h) was R&D on an export pipeline that turns planning reports and storyboards into an LLM-friendly form and converts them to pptx/pdf. After comparing WeasyPrint, Slidev, Typst, and LibreOffice — LibreOffice dropped as too heavy a dependency — I settled on Typst as the PDF typesetting backend with a python-pptx-style path for native pptx. The working tree now holds runtime/export/ (render-pptx.js, render-typst.js, planning-deck.js, convert-pdf.js, pack.js), token packs under templates/ (creative-warmth, keynote-minimal-fullbleed, consulting-precision-grid, conti-grid), plus ExportMenu.tsx and server/routes/export.js. It’s uncommitted, so it’s absent from #6’s commit log. (This dovetails exactly with today’s slide-generation tooling post.)

In Flight: Firebase Auth

The other thread is bolting on login and per-user data management via Firebase. I planned it with /plan, started the implementation, and parked it on a separate branch to keep main clean before returning to main. A short final session ran a security review over the auth middleware (tests/api-auth-middleware.test.js and the auth components). Branch work, so not in #6’s commit log either.

Infra: EventBridge / EC2 Cron Verification

The day opened with verifying that the EC2 cron schedule wired into EventBridge via Terraform was applied correctly — confirming how long EC2 stayed up yesterday and that the schedule behaved as intended.

Commit Log

Insights

The gate-marker bug was not “the UI is wrong” but “the UI’s inputs arrive a beat late or change mid-flight” — the classic trap of SSE-driven real-time UIs. Both bugs were about the timing of state, not display logic: one a race where activeSessionId gets filled mid-stream, the other a lag where gate_emit’s final arrives late so the derived state (liveGate) trails the truth. The lesson for real-time derived state is to compute from “the running max of events already received” rather than “the current value” — but also to make explicit when that max can be trusted (i.e., which marker’s presence licenses the conclusion). Separately, dropping LibreOffice for Typst in the export pipeline landed on the exact conclusion I reached independently in today’s browsing — pulled twice into the same gravity well of tool choice.