#+TITLE: Widget Component Generation — Spec
#+AUTHOR: Craig Jennings
#+DATE: 2026-07-12
#+TODO: TODO | DONE
#+TODO: DRAFT READY DOING | IMPLEMENTED SUPERSEDED CANCELLED

* DRAFT Widget component generation
:PROPERTIES:
:ID:       3ac0d42c-db1a-4d21-bce4-e63785fef0ba
:END:
- 2026-07-12 Sun @ 10:12:06 -0500 — drafted.

** Prototype iterations
Per =claude-rules/ui-prototyping.md=, a non-trivial-UI spec carries its prototype evidence here. This spec's UI evidence is the [[file:../prototypes/panel-widget-gallery.html][panel widget gallery]] itself — the living catalogue is the prototype set, not a numbered iteration series:

- *Research:* reference photos of period hardware (Berna 3 studio suite, aviation clusters, broadcast consoles, pedals, marine/telegraph instruments) filed in [[file:../../working/retro-stereo-widgets/references/][working/retro-stereo-widgets/references/]]; in-chat-pasted references have provenance noted in card notes and the 2026-07-11/12 session archive.
- *Iterations:* the gallery's git history is the iteration record — N-series base widgets, then reference-derived R01–R31 built and behaviorally verified card by card (commits 7fff507 through 52a43ec, 2026-07-12). 84 cards total, every one CDP-verified (drag tracking, click response, animation, zero console errors).
- *Final:* the gallery as of 52a43ec is the settled visual + behavioral spec each component port is judged against.

* Metadata
| Status   | draft                             |
|----------+-----------------------------------|
| Owner    | Craig Jennings                    |
|----------+-----------------------------------|
| Reviewer | (spec-review pending)             |
|----------+-----------------------------------|
| Related  | [[file:../../todo.org][todo.org — Retro widget catalogue]] |
|----------+-----------------------------------|

* Summary
The panel widget gallery (84 behaviorally-verified retro-instrument cards) is a spec, not yet a library. This document defines how gallery cards become reusable components for three real targets — web (vanilla JS, the gallery itself as first consumer), Emacs (svg.el), and waybar (GTK CSS) — driven by actual demand rather than porting all 84.

* Problem / Context
The gallery grew card by card as a visual and behavioral catalogue: each card is a self-contained inline builder function inside one 2258-line HTML file. That was right for the collection phase — fast iteration, one canvas, one review surface. It is wrong for consumption: a waybar panel, an Emacs game, or a web UI that wants a VU meter today would have to copy-paste from the gallery's internals and hand-fork the styling.

The groundwork is already laid. Tokens are single-sourced in [[file:../prototypes/tokens.json][tokens.json]]; =gen_tokens.py= emits the gallery's =:root= CSS block, [[file:../prototypes/tokens-waybar.css][tokens-waybar.css]], and [[file:../prototypes/gallery-tokens.el][gallery-tokens.el]] (27 tests, 100% coverage). An svg.el proof widget ([[file:../prototypes/gallery-widget.el][gallery-widget.el]], the needle gauge, 10 ERT tests plus an rsvg-convert side-by-side render) proved the Emacs pipeline — the riskiest unknown — end to end. What's missing is the middle layer: parameterized, importable widgets per target, and a decision procedure for which widgets earn a port.

* Goals and Non-Goals
** Goals
- A consumer in any of the three targets can use a ported widget without reading the gallery's source.
- The gallery stays the single visual/behavioral spec; ports are judged against it, and the web port *is* what the gallery runs.
- Porting effort tracks demand: a widget is ported when a named consumer wants it, not because it exists.
- Every port carries tests in its target's idiom (CDP behavioral for web, ERT + visual harness for Emacs, panel test suite for waybar).

** Non-Goals
- Porting all 84 cards. Most cards are catalogue entries; a port with no consumer is inventory nobody asked for.
- Shared rendering code across targets. Reuse lives in shared tokens and shared SVG geometry math, not shared code — each target renders in its own idiom (recorded architecture decision).
- Framework wrappers (React or otherwise) ahead of a real framework consumer.
- Level-2/3 codegen (widget-spec → renderer generation) in this spec's v1 — that's the Phase 5 decision point, deliberately after hand-porting experience exists.

** Scope tiers
- v1: demand inventory, web library extraction, Emacs ports of the demanded widgets, one waybar pilot panel, the Level-2 generator go/no-go.
- Out of scope: new widget collection (R-series closed), shared cross-target rendering code, interaction parity beyond each target's native idiom.
- vNext (log to todo.org at hand-off): React/framework wrappers, Level-2/3 codegen if Phase 5 says go, ports beyond the demand matrix as consumers appear.

* Design
** For a consumer
Web: include =widgets.js= (classic script) after the token =:root= block; call a builder — e.g. =GW.vuMeter(el, {value: 0.6})= — and get back a handle with setters. The gallery page itself becomes a grid of exactly these calls, so the demo and the library cannot drift.

Emacs: =(require 'gallery-widgets)= (the =gallery-widget.el= pattern, one file per widget family or one shared file — Phase 3 sizes this); each widget is a function from parameters to an svg.el object, tokens resolved through =gallery-tokens.el=. Interaction (keymap, click regions) is per-widget Emacs idiom, not a translation of pointer drags.

Waybar: no widget functions — waybar consumes =tokens-waybar.css= plus the banked composition idioms (lit/unlit key states, LED rows, engraved captions). The pilot restyles one real panel (audio, in =~/.dotfiles=) so its GTK CSS reads from the generated token sheet; "component" at this target means a documented CSS pattern, because GTK CSS has no scripting surface.

** For an implementer
Three layers, already agreed: tokens (values) → widget spec (the gallery card: geometry, params, behavior) → per-target renderers. The card is the contract. A port re-reads the card's builder for geometry constants and behavioral rules (detent snapping, VU ballistics via the =vuDb()= law, exclusive-select), then re-expresses them natively. Geometry math (polar helpers, scale interpolation tables like =EDGE_SCALE=, =SEG14_MAP=) is copied deliberately per target and cross-checked by tests, not shared as a runtime dependency — the false-coupling judgment from the token work applies to code too.

Extraction order inside Phase 2: the card builders already share =svgEl=/=polar= helpers and document-scoped gradients/filters; lifting them means (a) moving each demanded builder into =widgets.js= behind a parameter object, (b) replacing its gallery card with a call, (c) re-running the existing CDP behavioral probes unchanged — the probes drive the rendered DOM, so a green re-run is the no-regression proof.

* Alternatives Considered
** Port everything to every target up front
- Good, because the catalogue would be uniformly consumable.
- Bad, because ~84 × 3 ports is months of work with no consumer for most of it, and unconsumed ports rot silently.
- Bad, because it front-loads the Level-2 codegen question before hand-port experience exists to answer it.

** Shared renderer core (one geometry engine, thin target adapters)
- Good, because geometry fixes would land once.
- Bad, because the targets' rendering models genuinely differ (DOM+CSS animation vs static svg.el re-render vs GTK CSS with no scripting); an abstraction spanning them is speculative and was already rejected in the recorded architecture decision.
- Neutral, because shared *values* (tokens) and shared *math* (cross-checked constants) capture most of the benefit without the coupling.

** Skip the web extraction; keep the gallery monolithic and port only outward
- Good, because it's less work now.
- Bad, because the gallery-as-demo property is lost: web consumers copy-paste internals, and the spec and any web usage drift apart immediately.
- Bad, because the extraction is cheap insurance — the CDP tests already exist to catch regressions.

* Decisions [7/8]
** DONE SVG-first substrate
- Context: curved dials, needles, glow filters must render identically enough across web and Emacs; librsvg reproduces gradients and blur filters.
- Decision: widgets with curved/needle geometry are authored as SVG in every scripted target; plain-CSS forms stay CSS only where the target is CSS-native (waybar).
- Consequences: easier — one geometry language, rsvg side-by-side verification works; harder — some pure-CSS gallery cards need SVG re-expression when ported to Emacs.
- Resolved live with Craig through the gallery/svg.el work (2026-07-11/12); proven by the needle-gauge slice (b137223).

** DONE Single token source
- Context: the amber retune required a 30-site find/replace before tokenization.
- Decision: =tokens.json= is the only place a design value is authored; =gen_tokens.py= emits all three target artifacts; generated blocks carry markers and are never hand-edited.
- Consequences: easier — one-line retunes, drift impossible; harder — adding a token means touching the generator (tested, 100% coverage).
- Resolved and shipped (4408779).

** DONE Per-target interaction layers
- Context: pointer drag has no Emacs equivalent; GTK CSS has no scripting.
- Decision: interaction is designed per target in its native idiom; only the widget's *state model* (positions, ranges, detents, exclusivity) is common, carried by the card.
- Consequences: easier — each target feels native; harder — behavioral parity is a per-port judgment, tested per target rather than shared.
- Resolved live with Craig (2026-07-11).

** DONE Demand-driven porting
- Context: 84 cards, three targets, most cards have no consumer today.
- Decision: a widget is ported when the demand matrix names a real consumer (a waybar panel, an Emacs game/UI, a web surface); the matrix is Phase 1's deliverable and Craig approves it.
- Consequences: easier — effort lands where it's used; harder — the catalogue stays partially ported indefinitely, by design.
- Agreed in the 2026-07-12 outline.

** DONE Gallery-as-spec
- Context: the ui-prototyping rule wants working prototypes as design evidence.
- Decision: the gallery is the canonical visual + behavioral spec; every port is judged against its card, and the web library's demo *is* the gallery.
- Consequences: easier — no separate spec artifact to maintain; harder — gallery regressions are spec regressions, so its CDP checks are load-bearing.
- Agreed in the 2026-07-12 outline; prototype evidence under the status heading.

** DONE Level-1 codegen only, for now
- Context: token codegen shipped; widget-level codegen (Level 2/3) is speculative before hand-port experience.
- Decision: defer the Level-2 go/no-go to Phase 5, after roughly five hand ports.
- Consequences: easier — no premature generator abstraction; harder — early ports carry hand-duplicated geometry constants until the decision point.
- Recorded architecture decision (2026-07-11 session).

** DONE Waybar pilot is the audio panel
- Context: the pilot should be a real panel with active development and a full test suite.
- Decision: the audio panel (=~/.dotfiles=) is the waybar pilot; archsetup owns the dotfiles work end to end per the standing rule in =.ai/notes.org=.
- Consequences: easier — freshest panel, known suite; harder — visual changes to a daily-driver panel need the manual-testing checklist.
- Agreed in the 2026-07-12 outline.

** TODO Web library packaging
- Owner / by-when: Craig / at spec-review.
- Context: the gallery is a single self-contained =file://= HTML page; ES modules don't load over =file://=, and a React consumer doesn't exist yet.
- Decision (proposed): =widgets.js= ships as a classic script exposing one namespace object (working name =GW=), loaded by the gallery via a relative =<script src>=; the shared helpers (=svgEl=, =polar=, =vuDb=, scale tables) move inside it. Framework wrappers are vNext, demand-gated.
- Consequences: easier — gallery keeps working from =file://=, zero build tooling; harder — no tree-shaking or import isolation (acceptable at this scale).

* Implementation phases
** Phase 1 — Demand inventory
Build the widget-to-target matrix from real consumers: walk the live waybar panels (net/bt/audio/maint), the Emacs surfaces Craig names (games, dashboards), and any web UI, and record which gallery cards each actually wants. Deliverable: a short matrix table in this spec's appendix, approved by Craig. Tree untouched.

** Phase 2 — Web library extraction
Lift the demanded cards' builders into =docs/prototypes/widgets.js= behind parameter objects; the gallery becomes calls into the library. Green re-run of the existing CDP behavioral probes is the no-regression gate. Each extraction batch leaves the gallery fully working.

** Phase 3 — Emacs ports
Extend the =gallery-widget.el= pattern for the demanded widgets: per-widget ERT (token resolution, geometry math normal/boundary/error, SVG structure, state-tracks-value) plus the rsvg-convert side-by-side visual harness against the gallery card. Keymap/click-region interaction designed per widget. Wired into =make test-elisp=.

** Phase 4 — Waybar pilot (audio panel)
Restyle the audio panel's GTK CSS onto =tokens-waybar.css= plus the banked composition idioms. Lives in =~/.dotfiles=; archsetup drives edit/test/commit/push end to end and drops the dotfiles inbox note. Visual result goes on the manual-testing checklist (daily-driver panel).

** Phase 5 — Generator decision point
After ~5 hand ports, revisit Level-2 codegen with evidence: how much of each port was mechanical duplication vs judgment. Deliverable: a go/no-go recorded as a decision here (go spawns its own spec). Tree untouched.

* Acceptance criteria
- [ ] Demand matrix exists in the appendix and Craig has approved it.
- [ ] Every demanded web widget is a =widgets.js= call in the gallery; CDP probes green; gallery renders unchanged from =file://=.
- [ ] Every demanded Emacs widget has ERT coverage and an rsvg side-by-side render matching its card; =make test-unit= green.
- [ ] The audio panel reads its palette from =tokens-waybar.css=; panel suite green; manual-testing checklist entry filed.
- [ ] Phase 5 go/no-go recorded as a dated decision.

* Readiness dimensions
Answer each, or write "N/A because…".
- Data model & ownership: =tokens.json= user-authored; =:root= block, =tokens-waybar.css=, =gallery-tokens.el= generated (marker-fenced, never hand-edited); =widgets.js= and Emacs widget files hand-authored; the gallery HTML owns card layout and demo calls.
- Errors, empty states & failure: builders validate parameter ranges and clamp (the gallery's existing behavior — e.g. no-cross flag clamps, detent wrap); Emacs widgets signal =user-error= on out-of-range tokens/params (the =gallery-widget-token= missing-token error is the pattern).
- Security & privacy: N/A because everything is local rendering of design assets; no credentials, no network.
- Observability: web — CDP probes plus zero-console-error checks; Emacs — ERT output; waybar — the panel's existing smoke/AT-SPI harness.
- Performance & scale: N/A beyond the existing gallery scale (84 cards render fine); ports are per-widget, no aggregate load.
- Reuse & lost opportunities: tokens and geometry constants reused by value with cross-checking tests; svg.el, librsvg, and GTK CSS used as the platforms provide them; deliberate non-reuse of cross-target code recorded above.
- Architecture fit & weak points: fits the shipped 3-layer architecture; weak point is spec drift between a card and its ports — mitigated by the side-by-side harness and by the gallery-as-demo property on web.
- Config surface: no new knobs; token values remain the only tuning surface.
- Documentation plan: =docs/prototypes/README.org= gains a consumers section (how to use =widgets.js= / the Emacs widgets / the waybar tokens); no user-facing docs beyond that.
- Dev tooling: existing =make test-unit= / =make test-elisp= cover new suites (tests auto-discovered under =tests/gallery-*=); =gen_tokens.py= unchanged; no new targets expected.
- Rollout, compatibility & rollback: web/Emacs are additive files; the audio-panel restyle is the one shared-state change — it rides the dotfiles repo, reverts with =git revert=, and changes styling only (no behavior).
- External APIs & deps: rsvg-convert and svg.el already proven by the slice; waybar GTK CSS subset already exercised by the live panels; no unverified assumptions.

* Risks, Rabbit Holes, and Drawbacks
- Pure-CSS cards demanded into Emacs need SVG re-expression — sized per widget in Phase 3; if one balloons, it goes back to the demand matrix rather than stalling the phase.
- The gallery extraction could tempt a rewrite-everything pass; the phase is scoped to *demanded* builders only, monolith remainder stays put.
- GTK CSS renders differently from the browser (no SVG filters, different gradient behavior); the pilot may reveal idioms that don't translate — acceptable, the pilot exists to find them, and findings feed the composition-idiom notes rather than blocking.
- Hand-duplicated geometry constants can drift before Phase 5; each port's tests pin its constants against the card's values.

* References / Appendix
- Architecture + banked variant/composition ledger: 2026-07-11/12 session archive (=.ai/sessions/=).
- Token generator: [[file:../prototypes/gen_tokens.py][gen_tokens.py]], tests in =tests/gallery-tokens/=.
- Emacs slice: [[file:../prototypes/gallery-widget.el][gallery-widget.el]], tests in =tests/gallery-widgets/=.
- Demand matrix: (Phase 1 deliverable — lands here.)

* Review and iteration history
** 2026-07-12 Sun @ 10:12:06 -0500 — Craig Jennings — author
- What: initial draft.
- Why: collection phase closed at R01–R31; porting needs a decision procedure and per-target shape before any consumer work starts.
- Artifacts: [[file:../prototypes/panel-widget-gallery.html][panel-widget-gallery.html]], todo.org "Retro widget catalogue" (DOING).