Add In-Flight Monitor count + activity spark design

docs/superpowers/specs/2026-08-14-inflight-activity-design.md

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+# In-Flight Monitor — Count + Activity Spark
+
+**Date:** 2026-08-14
+**Status:** Approved (design)
+
+## Summary
+
+Enhance the In-Flight Monitor action so its key shows the **number of
+in-flight requests** for the configured model plus a **count-trend spark**:
+a tiny line/area chart of that count over the last ~60s, so activity is
+visible even during a single long-running request.
+
+## Layout (72×72 SVG, rendered via `renderInflight`)
+
+- **Top:** model short name (small, white) — existing.
+- **Center:** the status. When `ready`:
+  - count > 0 → the **count number**, large/bold (e.g. `3`), on the red
+    `ACTIVE` background, with the existing pulse.
+  - count === 0 → `IDLE` on green — existing.
+  - `loading` → `LOADING`, `stopped` → `OFF`, offline → `OFFLINE`,
+    unconfigured → `NO MODEL`, unknown → `…` — all unchanged.
+- **Bottom strip (~14px):** the count-trend spark — a small polyline + faint
+  area fill of the model's in-flight count over the last 60 samples, in the
+  state color. Flat at the baseline when idle; spikes when requests come and go.
+
+## Data Flow
+
+- The feed side is unchanged — `InflightTracker` already exposes exact
+  per-model counts.
+- Each key's per-key state (in `inflight-monitor.ts`, keyed by
+  `ev.action.id`) gains:
+  - `history: number[]` — a 60-sample ring buffer of the live count.
+  - `sampler?: ReturnType<typeof setInterval>` — a 1s interval that pushes
+    `runtime.tracker.count(modelId)` into `history` and re-renders.
+    Started in `onWillAppear`, cleared in `onWillDisappear`.
+- Live feed events (`add`/`remove`/`snapshot`) still re-render the big
+  number immediately via the existing subscription; the spark refreshes at
+  1Hz.
+- `renderInflight` gains an optional `history?: number[]` field. Spark
+  scale: yMax = `max(max(history), 1)` so a zero line sits at the baseline.
+
+## Files
+
+- `src/lib/render.ts` — `renderInflight` accepts `history` and draws the
+  spark; center label shows the count when active.
+- `src/actions/inflight-monitor.ts` — per-key `history` ring buffer +
+  1s sampler.
+- `tests/render.test.ts` — new/updated assertions for count rendering and
+  the spark.
+
+## Error Handling / Edge Cases
+
+- Spark with <2 samples renders no line (like the GPU chart).
+- Sampler cleared on `onWillDisappear` (no leaks); multi-key safety
+  preserved (buffer + sampler live in the per-key map entry).
+- History capped at 60 samples.
+
+## Out of Scope
+
+- No change to the GPU Graph action, the feed, or the tracker.
+- No throughput-bar variant (count trend was chosen).