Platformer Level 6 "Cavern Depths" — the dirt biome (asset expansion Phase B, slice 1)

CHANGELOG.md

@@ -10,6 +10,25 @@ The native shim's ABI is tracked separately by `b2Version()` (currently `4`).
 
 ### Added
 
+- **Platformer: LEVEL 6 "CAVERN DEPTHS" - the DIRT biome (asset-expansion
+  Phase B, slice 1).** A sixth level built on the previously-unused
+  `terrain_dirt_*` tile set (block tops, `block_center` mass under the mound,
+  carved `block_top_left/right` cliff corners on the goal steps AND the spike-pit
+  lips, `ramp_long_a/b` dirt ramps, a one-way `cloud_left/middle/right` dirt
+  platform): a WALL-JUMP SHAFT of floating dirt columns (slot coin, the L3
+  ice-shaft recipe in dirt), a spike GAP to leap (checkpoint past it), a
+  DIRT-RAMP mound, a high one-way-cloud bonus route, two slimes + a snail, a
+  bonus GEM above the shaft, and carved dirt steps to the flag. The win moves to
+  L6 (`gLevel >= 6`); L5's flag now ADVANCES. **OXT round 1 polish (atmosphere):**
+  a built **dark cave backdrop** (`pfBuildCaveBackdrop` - two card graphics, not
+  the flat/blank `background_solid_dirt` frame), flickering **wall torches**
+  (`torch_on_a/b`, new `pfMakeTorch`), hanging **chains + stalactites**
+  (`terrain_dirt_vertical_bottom`), and ground decor (a rock, cave mushrooms, a
+  bush) - placed clear of every beat. Example-side only (no Kit change, no
+  harness bump); `tools/audit-platformer.py` auto-discovers and clears L6 (9
+  coins, 3 walkers, 0 findings). Statically verified; needs an OXT pass (see
+  header verify item 20). Phase B's headline mechanics - the block slime and the
+  conveyor belt - land in slices 2-3.
 - **Platformer: FISH in the swim pool.** The L1 hilltop pond now has two fish
   (blue + yellow, native `foes` art that was unused) swimming at different depths
   and periods — bodiless proximity hazards (recoverable knockback) you time your
@@ -29,6 +48,19 @@ The native shim's ABI is tracked separately by `b2Version()` (currently `4`).
 
 ### Fixed
 
+- **Platformer: spike pits now align FLUSH with the pit edges (all levels).**
+  Found over two OXT rounds:
+  - *Horizontal (the real misalignment).* `pfTile` treats its `(x,y)` as the
+    tile's TOP-LEFT (it centres at `x+32`, exactly like all the ground tiling),
+    but the spike row was tiled over the range `pL+32 .. pR-32`, shifting every
+    spike 32px RIGHT - a bare 32px gap at the left pit edge and the last spike
+    OVERHANGING onto the ground on the right. The row now tiles `pL .. pR-64`
+    (top-lefts), landing flush from `pL` to `pR` in every pit.
+  - *Vertical.* The spike pixels are the bottom 34px of the 64px cell, so the old
+    y576 sank the tips to y606 (30px below the edge); the tile now sits at y546 so
+    the tips meet the ground line.
+  Affects every spike pit (L1/L3/L5/L6); the hurt sensor and pit geometry are
+  unchanged. The no-art fallback strip matches.
 - **Platformer (OXT round 6): five polish fixes for a solid state.**
   - *Parallax seam.* Adjacent 640px backdrop panels met exactly edge-to-edge, so
     sub-pixel rounding leaked a 1px white hairline. Panels are now widened 4px and

docs/asset-expansion-plan.md

@@ -61,7 +61,7 @@ untouched** and every biome is missing its real terrain shapes:
 - **Water/lava dressing:** `water`, `water_top(_low)`, `lava`, `lava_top_low`.
 - **Flags:** `flag_green_a/b` (a third flag colour).
 
-### HUD strip (`tiles`, 33 frames — entirely unused)
+### HUD strip (`tiles`, 30 frames — entirely unused)
 `hud_character_0`…`9`/`multiply`/`percent`, `hud_coin`, `hud_heart(_half/_empty)`,
 `hud_key_blue/green/red/yellow`, `hud_player_*` and `hud_player_helmet_*` portraits.
 An art-driven HUD that **replaces the LiveCode text fields outright** — the
@@ -141,18 +141,30 @@ needs an OXT eye.
 - *OXT to confirm:* parallax tiling seam/feel; swim+fish balance.
 
 ### Phase B — Underground biome → **Level 6 "CAVERN DEPTHS"**  (M)
-- **Assets:** `terrain_dirt_*` (whole biome), `background_solid_dirt` +
-  `background_color_hills` far layer, `torch_off/on_a/on_b`, `conveyor`,
-  `slime_block_*` (block slime).
+- **Slice 1 — DONE (statically verified; needs OXT):** the **dirt biome + Level 6
+  skeleton** that completes start-to-finish. `terrain_dirt_*` (block tops,
+  `block_center`, carved `block_top_left/right` corners, `ramp_long_a/b`, one-way
+  `cloud_*`) over the `background_solid_dirt` backdrop; a wall-jump shaft of
+  floating dirt columns, a spike gap, a dirt-ramp mound, a one-way-cloud bonus
+  route, reused slimes + a snail, a bonus gem, dirt goal steps. Win moved to
+  `gLevel >= 6`. Example-side; `audit-platformer.py` auto-discovers + clears L6.
+- **Slices 2–3 — TODO:** the block slime (slice 2), then the conveyor + torches
+  (slice 3).
+- **Assets:** `terrain_dirt_*` (whole biome, slice 1), `background_solid_dirt`
+  (slice 1), `torch_off/on_a/on_b` (slice 3), `conveyor` (slice 3),
+  `slime_block_*` (block slime, slice 2).
 - **New enemy:** **block slime** — a hopping cube (slime family, new `slimeblock`
   kind; `_jump` frame on the hop, `_rest` between).
 - **New mechanic:** **conveyor belts** — a floor strip that pushes the grounded
-  hero (a kinematic surface velocity, or a polled zone that adds vx). Animated
-  `conveyor` tile.
+  hero (a polled zone that adds vx). **Correction:** the `conveyor` tile is a
+  **single frame** (no `_a/_b` pair), so the belt does **not** animate by frame-
+  flip — drive it as a polled vx zone with a static tile (or fake-scroll the tile
+  loc if motion is wanted). Only `torch_on_a/b` is a real 2-frame animation.
 - **Ambiance:** wall **torches** (2-frame `torch_on_a/b` flicker) light the cavern;
   the dirt biome's corner/edge/vertical tiles make real tunnels & cliffs.
 - **Level:** a descending cave run — conveyor sections, block-slime hops, a dark
-  vertical shaft (wall-jump), dirt ramps. Backdrop is the new dirt scene.
+  vertical shaft (wall-jump, **slice 1**), dirt ramps (**slice 1**). Backdrop is
+  the dirt scene (**slice 1**).
 - *Kit:* conveyor may want a tiny Kit helper (a "surface velocity" zone) — evaluate
   a polled example-side version first.