docs(design): integrated-glance concept — band below the module, one loop display, one selector (task D-40)

Zero-chrome always-open band replaces CurrentJamPanel below the
instrument row; ProgressionBanner survives as the single loop display
(RoadmapTrack retires, education folds into rail row headers); App
instrument state threads everywhere (JamGuide internal tabs die);
vertical rows, all stations expanded, playhead highlights; honest
wrap-based math (worst piano gallery 1,178px). Critic returned once
(Dm7-specific worst case + 3 factual fixes incl. the interim
page-yank), fixed, PASS on scoped re-gate (pixel-exact recompute).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/design/integrated-glance.md

@@ -0,0 +1,422 @@
+# Integrated Glance — the Jam Guide joins the main module (task D-40)
+
+> **Thesis:** the Jam Guide stops being the last collapsible at the bottom of the
+> page and becomes a **full-width, always-open band directly below the instrument
+> view** — the third element of the main module. The loop is shown **once**, in
+> ProgressionBanner (where the user says it already lives); the Roadmap track
+> retires and its education (solo scales, guide tones, voice-leading) folds into
+> the rail's station headers. The rail itself flips from the D-31 playhead
+> accordion to **all stations expanded at once, as vertical rows** — every loop
+> chord's full voicing gallery permanently visible, the playhead highlighting
+> (never revealing) the active row. One global GUITAR/PIANO/BASS selector — App's
+> existing `instrument` state — drives everything.
+>
+> User directive (2026-07-10, verbatim): *"i would like to move it up and
+> integrate it somewhat in the space of the main module up top. or maybe right
+> below it as it is super important. … i would like to be able to see the loop
+> clearly, no need to have this repeated again. as its already in the main module
+> … only one selection for GUITAR/PIANO/BASS and everything should show in that
+> instrument. … i'd like to see all the chords and their voicings in a specific
+> way in case a loop is detected (or at least just like 4 chords or something at
+> least, so you can follow and potentially learn new ways to play it while you
+> are playing the loop.) scrolling is easier then clicking"*
+
+**Decision authority:** per the sprint header (no user gate), Muse picks the
+strongest option and records rejected alternatives (§7). Implementation is
+**L-40** (App restructure, §6.1) then **D-41** (rail rework, §6.2). This doc
+supersedes `glance-mode.md` §1's accordion where they conflict — the user's
+scroll license overturns D-31's "everything expanded" rejection (Rejected A
+there), with the axis flipped to vertical (§4).
+
+---
+
+## 0. What exists today (read from the code)
+
+App.jsx mount order: `ProgressionBanner` (~609) → instrument row (~618–630:
+`Fretboard`/`BassFretboard`/`Piano` at 70% + `ProgressionSuggestions` 30%) →
+`CurrentJamPanel` (~634) → `LoopStation` (~642) → Debug/Drum/Tuner collapsibles →
+**`JamGuide` last (~712)**. The global `instrument` state (App.jsx:58,
+`'piano'|'guitar'|'bass'`) has its selector in the controls bar (~484) and drives
+the main instrument views + DebugView — but **JamGuide ignores it** and runs its
+own internal Guitar/Piano/Bass tabs (JamGuide.jsx ~405–434, local state ~208).
+
+The detected loop renders **twice**: ProgressionBanner's loop row (compact chips,
+active chip highlighted via `findLoopPosition`) and `RoadmapTrack` inside the
+JamGuide jam section (stations with solo-scale labels, guide-tone dots,
+voice-leading rails, playhead + beat grid). Below the Roadmap, `GlanceRail`
+(L-33) is a playhead **accordion**: one station's gallery expanded at a time —
+the exact "it changes when the chord is not playing" complaint.
+
+---
+
+## 1. Placement — a full-width band directly below the instrument view
+
+**Chosen: the Jam Guide content mounts as a full-width, always-open band
+immediately below the instrument row, replacing `CurrentJamPanel`'s slot (before
+`LoopStation`).** The four-section Knowledge Center dock stays at the bottom as
+the browse/study area, minus its jam section (§5).
+
+Why *below* the main module and not *inside* it:
+
+- **Width math kills "inside".** The only free space inside the main module is
+  the 30% `ProgressionSuggestions` column (~360px at 1280) and the banner's
+  interior. A single piano station's gallery is **~1,178px** worst case: the
+  gallery calls `pianoVoicing` with no `prev` (VoicingBrowser.jsx:161), and
+  MiniPiano's D-24 crop is C-aligned (`octStart = floor(minNote/12)`), so any
+  station rooted **above D** crosses the C boundary even in root position and
+  shell — recomputed G7: root [7,11,14,17], shell [19,23,29], rootlessA
+  [23,26,29,33], rootlessB [17,21,23,26] → **all four cells are 2-octave 284px
+  crops** ≈ 4×284 + 24 gaps + 18 chrome ≈ 1,178px. (glance-mode.md's ~940px was
+  the Dm7-specific figure; 1-octave root/shell crops exist only for roots C–D.)
+  Nothing gallery-shaped fits inside the module without crushing the neck/keys —
+  the surface the player's eyes track continuously.
+- **"The main module" to the user = banner + big instrument view** — the
+  real-time detection surface. The guide answers a different question ("what
+  can I play on each chord of this loop") at a different rhythm (study-while-
+  looping). Directly below = one saccade down, same screenful top edge, no
+  competition for the detection pixels. The user himself offered "or maybe
+  right below it" — and the space math makes that the only honest reading.
+- **Always open, zero chrome.** No collapse header (scroll past it if unwanted
+  — scroll > click), no section nav, no internal instrument tabs, no style
+  tabs, no level chips. The band is a pure auto surface: detection picks the
+  loop and style, the ONE controls-bar selector picks the instrument. The
+  `styleOverride`/style-tab machinery (JamGuide.jsx ~210–212, ~438–458) **dies
+  with the tabs**: the band always follows `match.style`; the heard-live
+  LicksStrip's `styleId` falls back to `styles[0]` when nothing is matched;
+  browsing OTHER styles stays reachable via the dock's own style chips
+  (LicksSection and ExploreSection each keep theirs). When no loop is matched
+  the band degrades to the existing "heard live" single gallery for
+  `currentChord`; when nothing is heard, a slim one-line hint (~40px) so it
+  never wastes main-module space.
+- The band gets a micro-header line (`JAM GUIDE — {matched name} · in C major`,
+  uppercase tracking-widest gray-500 style), not a button.
+
+Vertical position at 1280×900 (~860px usable): header ≈56 + controls bar ≈52 +
+banner ≈140 + instrument row ≈300 + margins ≈24 → **the band starts ≈570px
+down**; its first ≈290px are visible at rest, and one scroll-flick puts the
+whole rail at the top of the viewport (§4 math). Estimates for the module
+heights; verified figures for the rail.
+
+---
+
+## 2. The single loop display — ProgressionBanner survives, RoadmapTrack retires
+
+**Call: ProgressionBanner's loop row is THE loop display. RoadmapTrack is
+unmounted** (L-40 removes the import/mount; the file stays in place like the
+EducationPanel precedent — deletion filed to backlog).
+
+The user told us where the loop lives: *"no need to have this repeated again.
+as its already in the main module"* — i.e. the banner. The banner is compact,
+up top, always visible, and **already carries the playhead**: `findLoopPosition`
+highlights the active loop chip (accent glow + amber rn). There is nothing to
+absorb on that front — the beat grid's "current beat" was chord-accurate anyway
+(RoadmapTrack's own comment: "coarse, chord-accurate — matches
+ProgressionBanner"). **ProgressionBanner.jsx needs zero edits.**
+
+Honest disposition of RoadmapTrack's unique value:
+
+| RoadmapTrack feature | Disposition |
+|---|---|
+| Playhead (active station) | Already in the banner's loop chips — nothing lost |
+| Beat grid + progress bar | **Dropped.** It never showed sub-chord progress (chord-accurate by construction); the BPM readout already lives in the controls-bar badge. Loss: the downbeat tick visual. If missed, a slim progress underline beneath the banner's loop chips is a future 1-point polish — explicitly NOT in L-40/D-41 |
+| Solo-scale label per station ("G mixolydian") | **Folds into each rail row's header** (§4) via `soloScale` from theory.js |
+| Guide-tone lane (3rd filled / 7th hollow dots) | **Folds into each rail row's header** ("aim" dots, same accent-filled/hollow language) via `guideTones` |
+| Voice-leading rails (7→3 half-step arrows) | **Folds into a compact transition chip** at the end of each row header: "next: F→E · ½ step down" (via `voiceLeadingPairs`; wrap-around chip on the last row says "loop"). The between-columns arrow SVG dies; the information survives |
+| Station "next" lookahead glow | Superseded: next row gets a small "next" tag; the whole loop is visible anyway |
+
+Interim honesty: L-40 unmounts RoadmapTrack **before** D-41 builds the row
+headers, so for one gate cycle the solo-scale/guide-tone/voice-leading education
+is absent from the page (the banner still shows the loop; the accordion rail
+still shows voicings). Accepted — D-41 follows immediately in the same serialized
+chain; Critic should not flag the gap as a regression.
+
+---
+
+## 3. Instrument threading — one selector, honest bass
+
+JamGuide's internal `INSTRUMENTS` tabs, `COMPUTED_INSTRUMENTS`,
+`availableInstruments`, and local `instrument` state (JamGuide.jsx ~42–47, ~178–
+184, ~208, ~405–434) are **deleted**. App's existing `instrument` flows down as
+a prop. Full prop paths to every consumer:
+
+| Consumer | Path |
+|---|---|
+| GlanceRail (band) | `App.jsx instrument` (line 58) → `<JamGuide instrument={instrument}>` → `<GlanceRail instrument={instrument}>` (prop already exists; only its source changes) |
+| VoicingBrowser, heard-live fallback (band) | App → JamGuide → `<VoicingBrowser show={instrument}>` (JamGuide.jsx ~494) |
+| LicksStrip (band) | App → JamGuide → `<LicksStrip instrument={instrument}>` (both mounts, ~498 and ~757) |
+| `stationVoicings` memo (band) | App → JamGuide — the memo's `instrument` dependency reads the prop |
+| VoicingsSection (dock) | App → `<KnowledgeDock instrument={instrument}>` (§5) → `<VoicingsSection instrument={instrument}>` → its `<VoicingBrowser show={instrument}>` (ExplorePanel.jsx:425, today defaulting to `'both'`) |
+| LicksSection (dock) | **No prop** — LicksSection is a module-local function in **JamGuide.jsx:562** (NOT an ExplorePanel export), and its heading is already statically honest ("Guitar licks · tab reads high e on top…"); licks are guitar-only in the KB (C-20 schema), so an `instrument` prop would be dead on arrival. Recorded so nobody threads it |
+| ExploreSection (dock) | **No prop needed** — it renders progression chips + famous progressions, no instrument-specific renderer; chord taps open ChordDetailModal, which has its own user-driven Guitar/Piano tabs. Recorded so nobody threads a dead prop |
+| DebugView | Already receives `instrument` (App.jsx ~676) — untouched |
+
+The only `ExplorePanel.jsx` signature change is
+`VoicingsSection({ keyInfo, chordHistory, currentChord, instrument })`
+(its named exports are LevelChips / ChordPickerToolbar / GuitarGrid / PianoGrid /
+ExploreSection / VoicingsSection — no LicksSection there).
+
+### The honest bass state (until C-41/P-41/L-42 land)
+
+BassFretboard covers the main view; the KB has **zero bass content** and both
+gallery generators are wrong for bass (guitar shapes are not bass patterns;
+`pianoVoicing` is piano). Showing guitar diagrams under BASS would break the
+one-selector promise the user just made. Instead, when `instrument === 'bass'`
+and a loop is matched:
+
+- Station rows still render their full headers — chord, rn, solo scale, aim
+  dots. **Guide tones ARE the bassist's target notes**; none of this is
+  instrument-specific.
+- The gallery slot renders a computed **root · fifth · approach** line per
+  station: root name, fifth name, and the chromatic approach into the NEXT
+  station's root ("approach: G♯ → A", computed from `stations[i+1].rootPc − 1`
+  semitone — pure arithmetic on data the component already has; **no theory.js
+  change**). This is the honest useful minimum, not a placeholder.
+- ONE notice for the whole rail (not per row): *"Authored bass patterns are on
+  the way (blues first) — meanwhile: roots, fifths, and the approach into the
+  next chord."*
+- The licks strip hides under bass (guitar tab licks are noise to a bassist
+  mid-jam; under piano the strip keeps today's honest "guitar licks" heading).
+
+**What L-42 slots in:** a per-station `<BassPatternCard>` (new component,
+Luthier/Muse per the C-41 schema — 4-string, frets 0–15) mounted in the same
+gallery slot of each row, replacing the computed line **when the matched style
+ships a bass cell**; the computed root/fifth/approach line remains the
+per-station fallback for styles without bass content. The rail's row structure,
+highlight, and header need zero changes for L-42 — that's the contract.
+
+---
+
+## 4. The all-stations-expanded rail — vertical rows, playhead highlights
+
+**Axis call: stations are VERTICAL ROWS** — one row per loop chord, each row =
+station header + that chord's full horizontal voicing gallery; the page scrolls
+down. All rows render all cells, always. **The playhead HIGHLIGHTS the active
+row and never hides, collapses, or reveals content.**
+
+Why vertical beats all-horizontal: a 4-station piano loop laid out as expanded
+columns is ≈4 × 1,470px ≈ **5,900px wide** — continuous sideways tracking while
+playing, on the axis mouse wheels don't scroll. Vertically, the worst piano row
+is ≈ 284 (threaded cell — an authored LH 3-5-7-9 also crops 2 octaves) + 8 +
+1,178 (§1 gallery) ≈ **1,470px of cells**, which does NOT fit 1,240px usable —
+the gallery **flex-wraps to a second cell line** (~300px row height). **No
+horizontal scroll survives because rows wrap, not because they fit.** Rows stack
+~170–300px tall and ≥4 chords sit within one to one-and-a-half screenfuls —
+the "at least 4 chords so you can follow" ask, under the user's scroll license.
+
+### Row anatomy (canonical KB order, same as the banner's loop after rotation)
+
+- **Header (~30px):** chord label (gray-100 bold) + rn + "now" badge (accent,
+  when active) / "next" tag · solo-scale label ("solo · G mixolydian") · aim
+  dots (3rd filled accent, 7th hollow — RoadmapTrack's GuideDot language,
+  honest "5th" fallback kept) · transition chip ("next: F→E · ½ step down";
+  last row: "loop"). Header data via theory.js `guideTones` /
+  `voiceLeadingPairs` / `soloScale` — read-only imports.
+- **Gallery:** first cell = the *station's own* voicing — guitar: the KB play's
+  recommended shape badged "play" (when present); piano: the threaded/authored
+  `stationVoicings[i].voicing` labeled honestly (e.g. "LH 3-5-7-9") — this is
+  where the accordion's collapsed-thumb value survives. Then the full
+  VoicingBrowser gallery (`show={instrument}`, `dense`): every placeable guitar
+  shape / all four piano styles, each with its own ▶ (D-30 one-at-a-time
+  playback contract). Bass: the §3 computed line (later the L-42 pattern card).
+- **Active row:** `border-accent ring-2 ring-accent bg-accent/10` + "now" badge
+  + `aria-current="true"`. Inactive rows `border-border bg-surface`, opacity
+  floor 0.85 (never dim below AA). Tokens only; no new colour.
+- **Mic-feedback microcopy** once below the last row (rail-owned; galleries run
+  `dense`), as today.
+
+### Focus semantics — pin simplified
+
+With everything always expanded, the pin has nothing to hold open. It collapses
+to a **focus toggle**: tapping a row header toggles that station as
+`focusedStation` (renamed from `pinnedStation`, same JamGuide-owned state, same
+reset-on-loop/style/instrument-change effect, same `onFocusChord({rootPc,
+quality})` emission — the D-03 fretboard guide-tone contract is byte-compatible).
+A focused row shows an "aim on fretboard" chip; tap again (or the loop changes)
+to clear. `aria-pressed` on the header button, min 32px target,
+`focus-visible:ring-2 ring-accent` everywhere.
+
+**No auto-scroll.** The band lives in page flow, so `scrollIntoView` would yank
+the whole page while the user reads the looper below — the accordion's
+auto-centre effect is **removed**, not ported (deleted in the same L-40 commit
+that promotes the band, §6.1 step 2 — today it is contained only by the dock's
+70vh scroller, which the band no longer has). The playhead highlight travels;
+the user owns the scrollbar (their explicit preference). On 4-row loops the
+whole rail is one screenful anyway; on 8-row loops the banner up top always
+shows the position. (Internal-scroll variant rejected: a nested scrollbar caps
+the rail at ~62vh ≈ 3 rows — breaks the ≥4-visible goal at 900px.)
+
+### Licks strip
+
+Directly below the last station row, unchanged in behaviour: thumb LickCards
+(~165px wide, strip ≈190px tall with heading), context-sorted to the playhead
+station via the token-boundary matcher, strip-owned "fits X — now" ring, hides
+entirely when the style has no licks, hidden under bass (§3). One flick below
+the rows — consistent with its D-31 position in the scroll order.
+
+### Space math (verified numbers: guitar cell ~93px, piano cells 160–284px, piano gallery ~1,178px worst — §1, licks thumb ~165px)
+
+Row heights: guitar row ≈ header 30 + cells ~140 + padding ≈ **185px**; piano
+row ≈ 30 + one cell line ~125 + padding ≈ **170px** single-line, ≈ **300px**
+when the gallery wraps to two cell lines. Row widths (cells): guitar ≈ play
+cell + 3–5 gallery cells ≈ **460–650px**; piano ≈ threaded cell up to ~284 +
+gallery up to ~1,178 ≈ **~1,470px worst case**. Piano rows rooted above D with
+a true 7th — i.e. most stations of most jazz/gospel loops — exceed 1,240px and
+**wrap** (single-line piano rows exist only for roots C–D or triad qualities);
+rows never scroll horizontally.
+
+| Scenario | 1280×900 (~1,240×860 usable) | ~640px wide (~576 usable) |
+|---|---|---|
+| 4-chord loop, guitar | 4×185 = **740px** — all 4 rows in one screenful (band scrolled to top); +190 licks strip = one flick more | cells fit one line (5×93+gaps ≈ 500); 4 rows ≈ 740px ≈ 1.3 screenfuls |
+| 4-chord loop, piano | best case (roots C–D / triads) 4×170 = **680px** ≈ one screenful; honest 7th-chord case (the jazz flagship): rows wrap → up to 4×300 ≈ **1,200px ≈ 1.4 screenfuls** — still zero clicks; the scroll license covers it | gallery wraps to 2–3 cell-lines → row ≈ 300–430px; 4 rows ≈ 1,200–1,700px ≈ 2–3 screenfuls, zero clicks |
+| 8-chord loop (post-L-30) | guitar ≈ 1,480px ≈ **1.7 screenfuls** / piano ≈ up to 2,400px ≈ **2.8 screenfuls** — scroll, highlight travels, banner keeps the position | ≈ 2.5–6 screenfuls; still zero clicks |
+
+At rest (no scroll) the band's visible ≈290px shows the header line + ~1–1.5
+rows — enough to see the "now" row when it's early in the loop; one flick brings
+the rail to the top. The user licensed exactly this trade.
+
+---
+
+## 5. What remains below — the dock slims to three sections, CurrentJamPanel retires
+
+- **`KnowledgeDock`** (named export from JamGuide.jsx, §6.1): the bottom
+  collapsible keeps **Explore / Voicings / Licks & Techniques** — the browse
+  and study area (chord picker, KB progression browser, full lick grids, the
+  shared level filter). The **jam section is removed** (it IS the band now);
+  the dock's header drops the live match label and becomes static ("Knowledge
+  Center — browse & study"). Level-filter chips stay dock-only; the band shows
+  all levels (a glance surface filters nothing — directive 4).
+- **`CurrentJamPanel` is unmounted by L-40.** The backlog already flags folding
+  it; the band moving into its exact slot makes its duplication terminal
+  (voicing strips → the rail; similar progressions → Explore; per-chord scale
+  labels → row headers). Honest loss: its mode-level `SCALE_IDEAS` prose and
+  `STYLE_VARIATIONS` cards exist nowhere else — the existing backlog item
+  ("fold CurrentJamPanel's unique bits into the Knowledge Center") stays open
+  for Professor/Muse; the file is retired-in-place, deletion filed with
+  EducationPanel's. Note for Maestro: only `RiffDiagram.jsx` goes orphaned with
+  it — `ChordBox.jsx` is still imported by ChordDetailModal.jsx (lines 2, 58)
+  and ExplorePanel.jsx (lines 18, 170) and must **NOT** be deleted.
+- **LoopStation** does not move — the band replaces `CurrentJamPanel` directly
+  above it, so it ends up right below the jam surface it feeds for free.
+  Debug/Drum/Tuner collapsibles unchanged.
+- **ChordDetailModal, ProgressionSuggestions, Fretboard/Piano/BassFretboard,
+  ProgressionBanner:** zero edits.
+
+Resulting App.jsx order: banner → instrument row → **Jam Guide band** →
+LoopStation → Debug → Drum → Tuner → **KnowledgeDock**.
+
+---
+
+## 6. Migration order — bounded scopes, green at every commit
+
+Serialized: L-40 → D-41 (same surfaces). Each commit: `npm run build` +
+`node scripts/smoke.mjs` green; Critic gates.
+
+### 6.1 L-40 (Luthier) — App restructure + instrument threading + single loop display
+
+**Files:** `src/App.jsx` (mounts + prop pass ONLY — 🚨 audio callbacks, refs,
+AudioCapture props untouched, grep-gated), `src/components/JamGuide.jsx`,
+`src/components/ExplorePanel.jsx` (VoicingsSection signature only — LicksSection
+lives in JamGuide.jsx), `src/components/GlanceRail.jsx` (**one-line effect
+deletion only**, see step 2 — re-lock at promotion per the ledger row).
+**Not touched:** RoadmapTrack.jsx / CurrentJamPanel.jsx (unmounted, not edited),
+ProgressionBanner.jsx, VoicingBrowser.jsx, all `src/lib/**`.
+
+1. **Thread the instrument.** App passes `instrument` to the JamGuide mount;
+   JamGuide deletes its internal tabs/state/availability gating and consumes
+   the prop everywhere (§3 table); VoicingsSection gains the prop. Guide still
+   at the bottom, four sections intact. Green.
+2. **Split and promote.** JamGuide.jsx → default export `JamGuide` (the band:
+   micro-header + jam content, always open, no section nav) + named export
+   `KnowledgeDock` (collapsible, 3 sections, level filter). App mounts the band
+   in CurrentJamPanel's slot, retires the CurrentJamPanel mount, keeps the dock
+   last. **RoadmapTrack unmounted** (loop now shown exactly once — the banner).
+   The band body for now = existing GlanceRail accordion + LicksStrip +
+   heard-live/empty fallbacks. **Same commit, mandatory:** delete GlanceRail's
+   auto-centre effect (GlanceRail.jsx:56–67 `scrollIntoView`) — it is contained
+   today only by the dock's 70vh `overflow-auto` body; in page flow the nearest
+   scroller is the DOCUMENT, so every playhead advance would yank the whole
+   page — the exact failure §4 forbids. Promoting the band and deleting the
+   effect must land together. Green.
+3. **Honest bass state.** `instrument === 'bass'` + loop matched → the §3
+   computed root/fifth/approach rows + single notice (band-level; no further
+   GlanceRail edits). Green.
+
+### 6.2 D-41 (Muse) — the all-expanded rail
+
+**Files:** `src/components/GlanceRail.jsx` (rework), `src/components/JamGuide.jsx`
+(band wiring: pass `keyMode`, `pinnedStation` → `focusedStation` rename,
+LicksStrip/bass-slot composition into rows), `src/components/VoicingBrowser.jsx`
+(**optional**, `dense`-path styling only). **Not touched:** App.jsx,
+RoadmapTrack.jsx, ProgressionBanner.jsx, MiniPiano/ChordDiagram/LickCard, libs.
+
+1. **Rows.** Accordion → all-expanded vertical rows: every station renders
+   header + full gallery permanently; active row highlight (`aria-current`);
+   pin → focus toggle (same onFocusChord contract). The `scrollIntoView`
+   effect is already gone (L-40 step 2) — verify none is reintroduced. Green.
+2. **Absorb the roadmap.** Row headers gain solo-scale, aim dots, transition
+   chip (theory.js read-only imports); gallery gains the "play"/threaded first
+   cell. Green.
+3. **Reflow + verify.** Narrow (~640px) cell-wrap per row; eyeball 1280×900,
+   1280×800, ~640; AA/focus audit; verify **rows wrap and never scroll
+   horizontally** (the piano worst case ≈1,470px of cells does NOT fit 1,240 —
+   §4), and recompute the honest screenful counts against the §4 table. Green.
+
+---
+
+## 7. Rejected alternatives
+
+**Rejected A — the guide inside the main module** (banner absorbs the rail, or
+the rail replaces the 30% ProgressionSuggestions column). Killed by width math —
+and the corrected worst case only strengthens it: ~360px column vs a ~1,178px
+piano gallery (§1); inside the banner it competes with the
+key/history/now-chord — the one surface that must stay instantly readable. The
+user's "or maybe right below it" is the version of his own ask that survives
+arithmetic. Also rejected structurally: ProgressionBanner doing loops + history
++ now-chord + galleries is a god-component.
+
+**Rejected B — all-horizontal expanded rail** (stations as columns, every column
+expanded). The literal reading of "all voicings at once", and the axis the old
+accordion already had. With the corrected cell widths it gets worse, not better:
+4-station piano ≈ 5,900px wide; 8-station ≈ 11,800px; continuous sideways
+tracking on the axis wheels don't scroll, whole stations hidden off-edge at any
+moment — the directive's "follow while playing" fails exactly when it matters.
+Vertical rows carry the same content with zero horizontal scroll (rows wrap,
+§4).
+
+**Rejected C — RoadmapTrack survives as the single loop display** (banner's loop
+row dies instead). Keeps the education-dense artefact, but contradicts the
+user's own account of where the loop lives ("it's already in the main module"),
+costs ~230px of premium height above the rail, and the banner would still show
+near-loop-shaped history chips — the "repeated again" feeling survives its own
+fix. Folding the education into row headers (§2) keeps ~90% of the value at
+~30px per row.
+
+**Rejected D — keep the pin/accordion semantics inside the expanded rail**
+(pinned row grows a bigger gallery). With everything expanded there is nothing
+left to reveal; a "bigger on pin" state reintroduces layout shift mid-jam — the
+exact complaint. The pin's two real jobs (fretboard guide tones, "hold still")
+survive as the focus toggle.
+
+**Rejected E — internal max-height scroller for the band** (~50–62vh, contained
+auto-scroll). Caps visible rows at ~3 (< the user's "at least 4"), adds a nested
+scrollbar inside the page scroll, and only exists to enable auto-scroll the
+design doesn't want. Page flow + user-owned scrolling is simpler and matches
+"scrolling is easier than clicking".
+
+---
+
+## 8. Out of scope / flags for Maestro
+
+- **ProgressionBanner polish** (progress underline beneath loop chips) — future
+  1-pointer, only if the beat grid is missed. Not in L-40/D-41.
+- **Cleanup ticket:** RoadmapTrack.jsx, CurrentJamPanel.jsx and its now-orphaned
+  RiffDiagram.jsx join EducationPanel.jsx in the retire-then-delete backlog
+  item. ChordBox.jsx stays — it is live in ChordDetailModal + ExplorePanel (§5).
+- **`SCALE_IDEAS`/`STYLE_VARIATIONS` prose** (CurrentJamPanel's unique content)
+  — the existing fold-into-Knowledge-Center backlog item stays open.
+- **L-42 contract** (§3): bass pattern card mounts in the row gallery slot;
+  rail structure frozen for it.
+- No new tokens, no new dependencies, no KB/theory/audio changes anywhere in
+  this design. All figures either verified (guitar/licks cells from the D-31
+  gate; piano worst case recomputed at the D-40 gate — G7 all-284px, §1) or
+  marked as estimates (module heights).