# LANE C — venue interfaces (round 13, v3.0-beta: the district) → Lane D + Lane F

*PROCITY-C, 2026-07-15. R13 §Lane C. The district ships **three** venue archetypes behind `?gigs=1` —
`pub` (R12), and new this round **`band_room`** and **`rsl`**. A converts a chosen shop to a venue kind in
place (`shop.type = kind`); C keys the interior recipe off `shop.type`. All three return the SAME shape
(below), so Lane D drops rigs in and Lane F reads state with no per-kind branching. Non-venue rooms are
byte-identical (venue code only runs for `recipe.venue`, on its own seed sub-streams).*

*Verified (fresh context, seeds 20261990/1990/7/42/101 + 90-build venue soak): 0 throws · 0 carves ·
0 path-fails · 0 determinism-fails · leak geo0/tex0 · worst build 8.3 ms. Draws below.*

---

## 0. The pinned pose `ry` convention (ROUND13 debt #4) — READ THIS FIRST

**Canonical convention (all of C's poses use it):** a pose's `ry` is the yaw of a thing whose **front /
outward normal is local −Z at ry=0**, i.e. world-facing `(−sin ry, −cos ry)`. `counter.stand`,
`browsePoints`, `watchPoints` and `bandPoses` ALL follow it, and the box placeholder (`placeholder.js`) is
built to it (toes at −Z). This is the long-standing convention `keepers.js` greet math already assumes.

**The GLB fleet mesh is the outlier — it faces local +Z at ry=0.** Verified two ways in a fresh context:
- toe-bone probe (`toe − foot`, the anatomically-anterior direction) on 5 peds → `(0.05..0.14, +0.99)` = **+Z**.
- planting a fleet rig at C's `counter.stand.ry` via `spawnRig` (no flip) and dotting its forward against
  the intended customer-facing direction → **−0.99 (180° backward)**; at `ry+π` → +0.99.
- for contrast the box placeholder's foot mesh sits at z −0.076 → **−Z** (matches the convention).

**Finding: with the GLB fleet loaded, keepers AND browsers have been facing 180° backward since the fleet
was wired in.** `keepers.js` spawns rigs at `stand.ry` / `browsePoint.ry` with **no flip**, and the mesh
front is +Z, so the keeper faces the bar wall and the browser faces the aisle instead of the goods. The R12
band reads correctly only because `band.js` added `RY_FLIP = π`. The two actor kinds are **opposite**
(placeholder −Z, GLB rig +Z), so the current per-consumer state is inconsistent both ways:

| consumer | applies | placeholder (−Z front) | GLB rig (+Z front) |
|---|---|---|---|
| `keepers.js` (keepers, browsers) | no flip | ✅ correct | ❌ **backward** |
| `band.js` (band, crowd) | `+RY_FLIP` (π) | ❌ backward | ✅ correct |

**Recommended canonical fix (Lane D — visual only, NO golden moves, no C poses change):** normalise the
fleet at the source. In `rigs.js buildFigure`, rotate the cloned `inner` by π about Y so every GLB rig's
front becomes **−Z**, matching the placeholder and every C pose. Then:
- `keepers.js` stays flip-free and is now correct for GLB too (fixes keepers + browsers);
- `band.js` **drops** `RY_FLIP` (set to 0) — the poses already face right under the −Z convention;
- placeholder and GLB modes become consistent (no more mode-dependent facing).

One rotation at the source, delete every consumer flip. C's data does not move (pure poses, all −Z already),
so no golden is touched — it's the visual fix debt #4 anticipated. Repro handed to D in `C-progress.md`.

*(If D prefers to keep the flip per-consumer instead, the equivalent is: ADD `RY_FLIP` to `keepers.js`
spawns — but that leaves placeholder-mode keepers backward, so the source-normalise is the clean one.)*

---

## 1. What `buildInterior` returns for a venue (`shop.type` ∈ `pub` | `band_room` | `rsl`)

Everything below is **pure data on the return** (room-local coords, the ry convention pinned in §0). Lane D
drops rigs straight in; Lane F reads state — no new lifecycle vs. the R9 keeper/browser seam.

### `room.stage` — the band stage, now a **4-PIECE** (ROUND13 debt #3, null for non-venues)
```js
room.stage = {
  x, z,            // deck centre (against the back wall)
  w, d,            // deck size (m) — varies by kind (table below)
  deckY,           // deck top surface height (m) — front line stands here
  riserY,          // drum riser top height (m) = deckY + 0.16 — the drummer sits here
  frontZ,          // z of the deck lip (the crowd stands in front of this, +Z)
  bandPoses: [ { x, z, ry, role, y, seated? } ×4 ],
}
```
- `bandPoses[0..2]` = the **front line**: `role` ∈ `guitar` / `vocal` / `bass`, across the deck lip, `y = deckY`.
- `bandPoses[3]` = the **drummer**: `role: 'drums'`, `seated: true`, up-stage centre on the drum riser,
  `y = riserY` (= `deckY + 0.16`, the `fittings.js` stage riser). The riser mesh already exists in the stage
  fitting — the pose just seats the kit + drummer on it.
- **Lane D:** lift each member to **its own `pose.y`** (was `stage.deckY`; front line is unchanged, the
  drummer now sits 0.16 m higher on the riser). `role` hints the instrument — E's GLBs via `opts.instrumentFor(role)`
  (electric_guitar/bass_guitar/mic_stand/drum_kit), primitives otherwise (asset law). `seated:true` → seated bob.
- `ry = π` faces the audience (+Z) **under the pinned −Z convention** → apply your fleet flip per §0.
- **John may veto to a front-line trio** (charter): say so before you start and C ships `bandPoses` length 3
  (drop `[3]`), and F amends its `band==` smoke back to 3.

### `room.watchPoints` — the audience, **cap by kind** (empty `[]` for non-venues)
```js
room.watchPoints = [ { x, z, ry, dance, slotIndex } ]   // seeded floor poses, all facing the stage centre
```
- **Crowd cap by kind: `pub` 8 · `band_room` 8 · `rsl` 12** (the RSL is the crowd-cap stress case). The room
  fills what geometry allows up to the cap; **the count IS the crowd cap** (F asserts crowd ≤ `watchPoints.length`).
- `dance` seeded **~⅓ true** ("a bit of both"). D: `dance:false` → stand-and-watch idle; `dance:true` → bob/sway
  with a **seeded phase offset** (use `slotIndex`/coords). Every point walkable, reachable, clear of the keeper
  stand + browse points + stage/PA. Deterministic per `shop.seed`.

### `room.counter` / keeper — unchanged
The bar is a normal counter; the barkeep is just a keeper at `room.counter.stand` (R9 seam). *(Subject to the
§0 facing fix — the keeper is one of the actors currently backward with the GLB fleet.)*

### `room.audio.gigKey` — the live bed (ROUND13 debt #1)
`room.audio = { musicKey, toneKey, gigKey? }`. The manifest key **is** the gigKey, canonical form
**`gig-<genreKey>`** — no mapping table. F passes gig state via `opts.gig`:
```js
buildInterior(rslShop, THREE, { gig: { on: true } })   // → room.audio.gigKey === 'gig-covers'
```
- Genre resolves `opts.gig.genreKey` → the venue's own `shop.genreKey` (A sets it) → a kind default
  (`pub`→pubrock, `band_room`→grunge, `rsl`→covers). Present **only when a gig is on**.
- **Prefer `gigKey` over `musicKey`** while the gig plays. **Lane E** names the beds `gig-pubrock`,
  `gig-grunge`, `gig-covers`; a missing key → silence (audio law), band still visible.

### The venue table (C-owned tuning, FYI)
| kind | archetype bias | ceiling | deck `w × d`, `deckY` | crowd cap | genre → gigKey | dressing |
|---|---|---|---|---|---|---|
| `pub` | wide / hall | 3.6 m | `0.58·W × 2.0`, 0.32 | 8 | pubrock → `gig-pubrock` | pub tables, sticky carpet, bar |
| `band_room` | cosy / pokey / wide | **3.4 m (low)** | `0.62·W × 1.6`, **0.20** (barely a riser) | 8 | grunge → `gig-grunge` | near-empty standing room, tin-shed dingy |
| `rsl` | hall / wide | **4.0 m (tall)** | `0.50·W × 2.4`, **0.40** | **12** | covers → `gig-covers` | flock walls, club carpet, bistro tables, members' bar |

## 2. Quiet-night variant
No `opts.gig` → a normal interior: `stage` + `watchPoints` are still returned as data, but there's **no
`gigKey`** (room-tone + maybe the seeded radio `musicKey`), and D spawns no crowd. A seeded dark night reads
true — the venue is just a quiet pub/club.

## 3. Budgets (measured, seed 20261990, fresh context)
- **Empty shells** (`drawSweep` glb-off): band_room **124** · pub **126** · rsl **135** — town-wide worst
  161 (opshop/hall). ≤ 350. ✓
- **Gig-night incl. FULL crowd + 4-piece** (worst-case framing from the door): RSL **237 draws** asset-free
  (16 rigs: 12 crowd + 4 band) / **77** GLB, **40.9k tris**. pub 176/56. band_room 173/53. ≤ 350 draws /
  200k tris. ✓ *(Measured with all 12 RSL watchPoints filled — band.js still caps crowd at 8 in R12; raising
  it to the watchPoint cap is D's R13 item, so this is the forward-looking worst case.)*
- **90-build venue soak** (pub/band_room/rsl mixed): 0 determinism · 0 carve · 0 path-fail · worst 8.3 ms;
  leak geo 0 / tex 0.

## 4. The archetypes (C-owned, FYI)
`band_room` = a tin shed: small (cosy/pokey), low ceiling, barely-a-riser deck, near-empty standing floor,
bar in the corner — the PA is louder than the room. `rsl` = carpet-and-flock club: the biggest floor in
town (hall/wide), a proper raised stage at one end, bistro tables round the edge, members' bar, the biggest
crowd cap. Both reuse the `pub` venue machinery (`theme.js venueSpec` + `layout.js` placeStage/placeWatchPoints);
only the dressing + `venueSpec` differ. Stage/PA/amp keep their GLB slots for Lane E (primitive fallback holds).