chore(maps): bump to 0.5.7; README cell-tile path subsection

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -1,11 +1,75 @@
 # lib-core.maps
 
-Single tile-grid map implementation. Loads JSON map + tilemap files, registers maps by id, and provides tile-fetch + walkability + size queries with current-map sugar.
+Multi-layer tile-grid map implementation with vertex-painted autotile
+(blob-14), sparse per-cell overrides, packed-u32 GID legacy path, atlas
+loading + UV resolution, walkability + sight-blocking queries, and a
+v3 multi-layer render pipeline with opaque-ceiling cache.
 
-**Version:** 0.2.0  
-**Lib-ID:** lib-core.maps  
-**Requires:** (none)  
-**Tags:** maps, tile-grid, walkability, tilemap
+**Version:** 0.5.7
+**Lib-ID:** lib-core.maps
+**Requires:** (none)
+**Tags:** maps, tile-grid, multi-layer, vertex-painting, autotile, blob-14, override, walkability, tilemap
+
+## Schema versions
+
+| Version | Highlights |
+|---|---|
+| v1 | Single-layer `tiles[]` + tilemap path. Loaded but auto-upgraded to v2 on `maps.load`. |
+| v2 | Multi-atlas + multi-layer with packed-u32 GIDs (atlas_idx + tile_id + rotation). `set_cell_gid`, `save_to_disk`. |
+| v3 | Per-layer `material` (atlas-alias), optional `vertices` ((W+1)·(H+1) grid), optional `overrides` ({"x:y": int OR {slot, rot, flip}}). Renderer derives slot/rot/flip from neighbour-bitmask blob-gating; overrides force-place specific orientations. |
+
+## Painting model (v3 autotile, dual-grid)
+
+Two grids offset by half a tile. The PAINT grid (called `vertices` in
+storage, "map-tiles" in design docs) is what users paint. The RENDER
+grid (called `cells`) is offset by (+0.5, +0.5) tile and is where
+sprites sit. Each render-cell spans 4 surrounding paint-tiles which
+act as its 4 corners (TL, TR, BL, BR).
+
+- **Paint grid**: (W+1)·(H+1) cells. Any-corner rule: render-cell
+  (x,y) is material iff any of its 4 corner paint-tiles is painted.
+- **Bitmask + SLOT_LOOKUP** (0.5.6 dual-grid native): each material
+  render-cell's 8-bit neighbour-bitmask (clockwise from N) is derived
+  from its own 4 corner paint-tiles — cardinal bit set iff ≥1 of the
+  edge's 2 paint-tiles painted, diagonal bit set iff the corner
+  paint-tile is painted. Blob-gating then zeroes diagonals whose 2
+  adjacent cardinals are not both set. The gated bitmask maps to one
+  of 14 canonical slots × {0,1,2,3} rotation × {0,1} flip via a
+  D4-orbit table.
+- **Override sublayer**: sparse `{"x:y": slot}` or `{"x:y": {slot, rot,
+  flip}}`. Takes precedence over the bitmask-derived slot AND forces
+  material-presence on the cell.
+
+**0.5.6 fix:** pre-0.5.6 derived the bitmask from the material status
+of the 8 neighbour render-cells, which violated dual-grid semantics —
+two cells whose shared edge had no painted paint-tiles still saw each
+other as material whenever any unrelated corner of either was painted,
+producing connected blobs across visually empty paint-tile gaps. See
+plan `2026-05-29-painting-model-rethink`.
+
+### Cell-Tile material path (0.5.7)
+
+A second, optional painting path: each layer can now also have a
+`cells_material` array (W·H bool, lazy-allocated). Cells where
+`cells_material[x, y]` is set use the classical 47-blob 8-neighbour
+bitmask rule on effective material (vertex-derived OR cell-derived),
+unlocking all 14 atlas slots. Cells whose material comes only from
+the vertex grid continue to use the FIX-A 4-own-corner rule (5
+reachable slots, dual-grid look).
+
+Both paths coexist in the same layer; the bitmask rule is decided
+per-cell based on whether `cells_material[x, y]` is true. A
+vertex-only cell adjacent to a cell-tile cell remains structurally
+blind to its neighbour because its 4-corner rule only reads its own
+corner vertices — this asymmetric seam is documented behaviour. For
+clean visuals use a single painting path per layer.
+
+Public API: `set_cell_material(layer, x, y, painted, map_id?)` and
+`get_cell_material(layer, x, y, map_id?) -> bool`.
+
+The `cells_material` field is optional and absent on every existing
+v3 map; save output is byte-identical to 0.5.6 when no cells_material
+entries are non-zero.
 
 ## Topology
 
@@ -20,6 +84,51 @@ graph LR
 
 ## API
 
+> **Note:** the API section below was authored against v0.2.0 and is
+> being progressively updated. Entries marked `[v0.x added]` are the
+> additions since 0.2.0. See `init.lua` source for the full surface.
+
+### APIs added v0.3.0 — v0.5.4 (summary)
+
+- **v0.3.0** — atlas-baker integration: `load_textures(asset_aliases)`
+  rewrite for M.2 atlas format; height-field API; atlas-bootstrap
+  stub when tilemap JSON missing.
+- **v0.4.0** — write-APIs for editors / procedural-gen:
+  - `set_cell_gid(layer_name, x, y, gid, map_id?)`
+  - `set_roof(x, y, value, map_id?)`
+  - `save_to_disk(map_id, path)`
+- **v0.5.0a-e** — schema-v3 multi-layer terrain stack:
+  - 8 layer slots (`foundation`, `subsurface`, `surface`, `topsurface`,
+    `lower_wall`, `wall`, `upper_wall`, `canopy`)
+  - `LAYER_Z` + `LAYER_ORDER_TOP_DOWN` constants
+  - Vertex-painted autotile renderer (any-corner + blob-14 SLOT_LOOKUP)
+  - Empty-layer + opaque-ceiling caches for render-opt
+- **v0.5.0d** — sparse override sublayer:
+  - `set_override(layer_name, x, y, slot_or_entry, map_id?)`
+  - `clear_override(layer_name, x, y, map_id?)`
+  - `get_override(layer_name, x, y, map_id?)`
+- **v0.5.1** — override-entry format extension to `{slot, rot, flip}`
+  (object form, backwards-compat with bare integer). Auto-compacts to
+  bare int when canonical orientation (rot=0+flip=0). `tile.opaque`
+  flag consumed from atlas-baker v0.2.0 alpha-analysis.
+- **v0.5.2** — public vertex-grid write APIs:
+  - `set_vertex(layer_name, vx, vy, painted, map_id?)` — any-corner
+    rule fills up to 4 cells; lazy-allocates grid on first paint
+  - `get_vertex(layer_name, vx, vy, map_id?) -> bool`
+- **v0.5.3** — bugfix: `load_textures` now refreshes the
+  `atlas_by_alias` dict after replacing `m.atlases[i]`, fixing the
+  v3 vertex/material render path which was resolving through the
+  pre-load stub (no texture handle → MISSING_ASSET_COLOR fallback).
+- **v0.5.4** — public atlas accessors for palette consumers:
+  - `atlas_diffuse_handle(atlas_idx, map_id?)` — raylib texture handle
+  - `atlas_tile_size_px(atlas_idx, map_id?)` — int, usually 64
+  - `atlas_tile_uv(atlas_idx, slot, map_id?)` — `{x, y, w, h}` in
+    atlas pixel coords, or `nil`. Resolves slot via the same
+    `slot_NN_` name regex used internally by the renderer.
+
+### Original v0.2.0 entries
+
+
 ### `maps.load(path)`
 **Syntax:** `maps.load(path: string) -> string`
 
@@ -286,6 +395,20 @@ maps.draw_map_post_entities()
 
 **Description:** Draws all post-entity layers of the current map (`lower_wall` through `canopy`). Must be called after entity rendering when using the split draw model. No-op if no current map.
 
+### Write APIs (v0.4.0+)
+
+#### `maps.set_cell_gid(layer_name, x, y, gid, map_id?)`
+
+Writes a single cell into the named layer of the current (or named) map. The layer must be one of `VALID_LAYER_NAMES`; bounds are checked against `map.size`. If the layer does not yet exist on the map it is allocated and initialised to all-zero before the write. Sets an internal `_dirty` flag so callers (e.g. the map-editor) can track unsaved changes.
+
+#### `maps.set_roof(x, y, value, map_id?)`
+
+Writes a single roof flag (`0` or `1`) at the named cell. Allocates the roof array on demand if the map did not previously have one. Same bounds-check as `set_cell_gid`. Throws on values other than 0 or 1.
+
+#### `maps.save_to_disk(map_id, path)`
+
+Serialises the in-memory map to v2 JSON and writes it to `path`. Output is pretty-printed with 2-space indent and is byte-deterministic for the same map state (sorted object keys, fixed array order). Reverses the internal atlas-resolution back to atlas-ID strings on disk. Resets the `_dirty` flag on success.
+
 ## Conventions
 
 - Pixel-coords + tile-coords kept distinct: `size`/`tiles` index in tile-units; `tile_size` is the conversion to pixels.

manifest.lib

@@ -1 +1 @@
-{"id":"lib-core.maps","version":"0.2.0","api_min":"0.1"}
+{"id":"lib-core.maps","version":"0.5.7","api_min":"0.1"}