platformer: expand Scorched Dunes (L5) to three acts (length + variety)

CHANGELOG.md

@@ -10,6 +10,61 @@ The native shim's ABI is tracked separately by `b2Version()` (currently `4`).
 
 ### Added
 
+- **Platformer: MULTI-KEY doors + a two-key puzzle in L2 (asset-expansion Phase C,
+  slice 3 - part 1).** `pfMakeKeyDoor` was single-instance (one door per level via
+  shared globals); it now appends to a per-door table, so a level can plant
+  several coloured key+door pairs. The hero carries a SET of keys (`gKeysHeld`,
+  shown in the HUD as `[KEYS yellow,blue]`); each key tags itself `uPfKeyWord` =
+  its colour, rides along the shoulder (fanned out when you hold several), and is
+  CONSUMED when it opens its own colour of door (`pfTickDoors` loops every door).
+  Single-door levels (L3's red door) are unchanged. **L2 "The Works"** now ends on
+  a **two-key lockgate** - its stone VAULT finale was extended (~5,884 -> ~6,312px)
+  into a proper corridor so the yellow gate, a stretch, the blue gate and the steps
+  are each their own beat (the first cut had the blue door embedded in the goal
+  step) - and gains coins to **25** (was 19).
+  Example-side only; gates clean, audit 0 findings.
+- **Platformer: latching SWITCH-GATES + a switch puzzle in L2 (Phase C slice 3 -
+  part 2).** `pfMakeSwitchGate pSwitchX, pColour, pGateL` plants a floor/ledge
+  switch (`switch_<colour>`) and the coloured kinematic gate (`block_<colour>`)
+  it opens. Unlike `pfMakeGate`'s momentary pressure pad, it **latches**: step on
+  the switch once and the gate rises out of the way for good (`pfTickSwitchGates`
+  polls only-moving-bodies, then `gSwDone` idles it in one compare/frame). L2 gets
+  a **green switch-gate** - the gate bars the crusher alley until you climb to the
+  third-bay cloud and press the switch up there, a "find the switch" beat (both
+  the keys and the switch are `gToysOK`-gated, so a missing tiles sheet degrades to
+  an open run). Example-side only; gates clean, audit 0 findings. Slice 3 done.
+- **Platformer: LEVEL 7 "STONE KEEP" expanded to a blade-and-warden gauntlet (the
+  length + variety pass, vertical edition).** The climbing tower roughly doubles
+  in height (1,280 -> ~2,300px, **8 -> 16 ledges**) and goes from 8 coins / 2
+  spinners to **~22 coins / 2 bonus gems** and a real bestiary - all chosen to
+  work in a *vertical* shaft (bats/ghosts/snails/mimics hardcode a horizontal
+  ground-y and were ruled out): **five sweeping spinners** guarding the climb gaps
+  (each verified standing-safe on both adjacent ledges), a **stationary
+  half-blade** (`pHalf`) on the final ledge, and three **wardens** on the wide
+  "fight" ledges - a `pfMakeSlime` to stomp, a `pfMakeFrog`, and a spike-slime to
+  dodge (the makers that take an explicit surface-y, so they ride the one-way
+  ledges). `pfDressWall` now tiles the taller shaft. Example-side only; the
+  geometry audit skips vertical levels, so the spinner safety + ledge spacing were
+  hand-verified (script gates clean, L1-L6 still 0 findings). **Needs the OXT
+  pass** (the vertical-only checks: walkers resting on one-way ledges, the
+  spike-slime leap, blade timing).
+- **Platformer: LEVEL 5 "SCORCHED DUNES" expanded to a full three-act level (the
+  length + variety pass, second of the audit).** From 4,200px / 12 coins / 3 foes
+  to **~6,400px and 24 coins**, keeping Act 1 verbatim and appending two desert
+  acts across three thorn pits: **Act 2** a darting `fly` (mover), a second dune a
+  sand `pfMakeBoulder` rolls down at you (re-parks at 4160 so the landing bank
+  stays safe), a high sand-cloud route, a fire `pfMakeCritter` (no stomp) and a
+  second `pfMakeFrog`; **Act 3** a treasure `pfMakeMimic`, a second fly, a final
+  cloud route and a homeward snail to the summit. Three checkpoints (now using
+  the fixed multi-checkpoint path). Example-side only; geometry audit clean (it
+  caught a summit coin overlapping the flag - fixed), 0 findings across 7 levels.
+- **Platformer: multi-checkpoint activation fix.** `pfMakeCheckpoint` tracked the
+  flag + its x in single globals that each call overwrote, and the sensor handler
+  banked that one x behind a one-time guard - so L6's three checkpoints left all
+  but the last dead (the first never lit, a later one stood pre-raised). Each flag
+  now carries its own respawn x (`uPfCheckX`) and a one-shot guard
+  (`uPfCheckDone`); touching a flag activates THAT flag and only ever advances the
+  respawn point. Single-checkpoint levels (L1-L4) are unchanged.
 - **Platformer: LEVEL 6 "CAVERN DEPTHS" expanded to a full three-act level (the
   length + variety pass).** The thinnest level (2,976px, 9 coins, 3 foes) grows
   to **~6,400px and 24 coins** with a rich cave bestiary, keeping all of Act 1

docs/asset-expansion-plan.md

@@ -187,7 +187,16 @@ needs an OXT eye.
   sweeping blades across the L1->L2 and L4->L5 climb gaps, standing-safe on the
   adjacent ledges. `pHalf` provides the wall-mounted `spinnerHalf` for slice 3.
   Gated on `gSpooksOK` (no `enemies.png` = safe). **Blade timing is the OXT feel-pass.**
-- **Slice 3 — TODO:** the **multi-key / switch puzzles** — the keep's real identity.
+- **Slice 3 — DONE (pending OXT):** the **multi-key / switch puzzles**, woven into
+  L2 "The Works" (L7 went vertical, so the puzzle wing lives in the machinery
+  level - switches/gates/keys fit a factory). *Part 1:* `pfMakeKeyDoor` generalised
+  to N coloured doors (a per-door table; the hero holds a `gKeysHeld` set, each key
+  `uPfKeyWord`-tagged and consumed at its door) - deployed as a **two-key lockgate**
+  (yellow + blue) ending L2, which also tops L2 to ~24 coins. *Part 2:*
+  `pfMakeSwitchGate` - a **latching** floor switch (`switch_<colour>`) that opens
+  its coloured kinematic gate (`block_<colour>`) for good - deployed as a **green
+  switch-gate** barring the crusher alley until you find + press the switch on the
+  third-bay cloud. Both gated on `gToysOK` (a missing tiles sheet = an open run).
 - **Assets:** `terrain_stone_*` (full), `switch_{blue,green,red}(_pressed)`,
   `key_{blue,green}`, `lock_{blue,green}`, `spinner*`/`spinnerHalf*`,
   `block_strong_*`.