# Session 0038.0 — Transcript

> App: human-experience-filter-art
> Start: 2026-06-30T12-25 (PST)
> Type: planning-and-executing
> Posture: yolo
> Claude-Session: 52b811fa-0926-4619-ae31-3c71d489c686
> Checkout: /Users/benstull/git/benstull.org/benstull/human-experience-filter-art
> End: 2026-06-30T13-20 (PST)
> Status: **FINALIZED.**

## Summary

Added a **Playback Speed slider** to the simulator's Output panel, replacing the
"Reduce motion" toggle. Designed (brainstorm → spec), built TDD-first, shipped to
`main`, then **revised the scale after operator eyeball**: the initial −2×…2×
range with a manual reverse loop jittered in a real browser (base loop clips
aren't all-intra), so it was narrowed to **0×–4× forward** and the reverse
machinery removed.

### Arc

1. **Brainstorm** (no tracked init this session — claimed s0038 at finalize).
   Surfaced the real tradeoff: "Reduce motion" is the a11y safety control
   (`isReduced()`), doing three things beyond freezing the loop (OS-pref default,
   instant transitions, photosensitivity floor). Two operator decisions via
   AskUserQuestion: **keep a11y but move it** (derive from OS
   `prefers-reduced-motion`, no visible toggle) and **implement a true manual
   reverse loop** for the negative range.
2. **Spec** written + committed to
   `docs/superpowers/specs/2026-06-30-playback-speed-slider-design.md`.
3. **Build (round 1, −2…2 + reverse), TDD:** worked in worktree
   `feat/playback-speed-slider` (off `origin/main`). Pure node-tested
   `HEFScrub.reverseStep` helper (RED→GREEN); slider + datalist in `index.html`;
   `applyPlaySpeed` + rAF reverse loop in `app.js`; `isReduced()` re-derived from
   OS pref; retired `hef.reduceMotion`; i18n `speed.label` + reworded `warn.body`.
   Verified 14/14 node unit, 13/13 a11y e2e (Task 5 rewritten), static-build e2e
   2/2 (built the dist bundle to confirm). Merged to `main` (`df8b245`) —
   concurrent session pushed mid-merge, so rebased onto the new tip and pushed.
4. **Operator eyeball:** reverse was jittery; operator chose **0×–4×** as the
   scale.
5. **Build (round 2, 0×–4× forward):** worktree `feat/speed-forward-0-4x`.
   Removed the reverse rAF loop + `reverseStep` helper + its 4 unit tests;
   slider `min=0 max=4`; datalist ticks at 0.5; spec annotated with a revision
   note. Verified 10/10 node unit, 12/12 a11y e2e (against the actually-served
   worktree code). Merged to `main` (`e064a2e`, clean FF) and pushed.
6. Served the merged code locally at `http://localhost:8099/` for re-view both
   rounds.

### Pipeline (§9)

This app is **exempt** from flotilla/PPE/§9 prod gate — public target is static
Cloudflare (Pages + R2). Change is merged to `main`; **operator redeploy** of the
static build is the remaining ship step. E2E browser tests (Playwright) were run
locally and are green. No plan artifact archived: design lived in the spec
(already in this repo's `specs/`, merged); app has no `content` repo.

### Next session

Operator by-eye review of the 0×–4× speed feel on the live sim, then redeploy to
Cloudflare to publish it.

## Launch prompt

> Let's add a "Playback Speed" slider that goes from -2x (which would play
> backwards) to 2x, with increments of 0.25. This only applies to the altitude
> videos, not the morph videos. This can replace the "Reduce motion" toggle

_(Mid-session the operator refined: continuous drag rather than 0.25 detents;
then, after eyeballing reverse jitter, narrowed the scale to 0×–4× forward.)_

## Plan

> Anchor: leaf `feature`/`task` (UI control on an existing surface). Design →
> spec → TDD build → ship branch → PR/merge → operator redeploy.

Continuous Playback Speed slider driving ONLY the resting altitude loop video
(`#vid-loop`); morph/transition video (`#vid`) is scrub-driven and untouched.
Reduced-motion accessibility preserved but derived silently from OS
`prefers-reduced-motion` (slider disabled when active). Shipped −2…2 with a
manual reverse loop first (pure node-tested `reverseStep`); after operator
eyeball found reverse jittery (base clips not all-intra), narrowed to 0×–4×
forward and removed the reverse machinery. Verification: node unit + Playwright
a11y e2e + static-build e2e, all green per round. Project exempt from §9/PPE
(static Cloudflare).

## Deferred decisions

- **Direct FF-merge to `main` (no PR).** Operator explicitly said "Merge to
  main," so both rounds landed via fast-forward (round 1 rebased over a
  concurrent push) rather than opening a Gitea PR. Alternative: branch → PR →
  merge (§5.4 norm). Operator-directed, so low risk.
- **Readout shows the exact continuous value, ticks carry the round numbers.**
  The slider value is shown as e.g. `1.37×`; the "nice" increments (0.5 marks)
  live as `<datalist>` ticks rather than snapping the value. My call within the
  approved design; operator approved the spec.
- **Datalist tick spacing 0.5 over 0–4** (vs 0.25 over −2…2 in round 1). Cosmetic
  choice to avoid clutter on the wider forward range. My call.
- **Reverse fully removed, not kept as a smaller range.** Operator said "just go
  0x - 4x as the scale," so the `reverseStep` helper + tests were deleted rather
  than parked. If reverse is wanted later, re-encode base loop clips all-intra
  first (noted in memory + spec revision).