Fixing tests and comments

kiln-core/CLAUDE.md

@@ -20,7 +20,7 @@ The core types that were formerly monolithic in `game.rs` are now split into foc
 **`kiln-core/src/archetype.rs`** — element taxonomy:
 - `Archetype` (`Copy`, `PartialEq`, `Hash`) — enum of named element types: `Empty`, `Wall`, `Crate`, `HCrate`, `VCrate`, `Builtin(Builtin, &'static str)`, `ErrorBlock`. Each variant provides `behavior()`, `name()` (used in map files), and `default_glyph()`. `Crate` pushable any direction (CP437 ■, char 254); `HCrate`/`VCrate` pushable east/west (↔, char 29) / north/south (↕, char 18) only. `ErrorBlock` is a sentinel for unknown archetype names (yellow `?` on red). `TryFrom<&str>` checks the `Builtin` registry first (via `Builtin::from_name`), then the hard-coded terrain names; unrecognized names return `Err` (the map loader substitutes `ErrorBlock`).
 - `Builtin` (`Copy`, `PartialEq`, `Hash`) — the family enum for all script-backed archetypes: `Gem`, `Heart`, `Pusher`, `Spinner`, `Key`. Generated by the `builtins!` macro (see below) along with all its methods. `Archetype::Builtin(family, alias)` carries both the family (selects the behavior and script source) and the specific alias matched during parsing (e.g. `"pusher_north"` or `"spinner_cw"`); the alias drives the per-alias glyph, the `BUILTIN_<alias>` tag on the expanded object, and the compile-cache key.
-- `macro_rules! builtins!` — the declarative registry for script-backed archetypes. Each entry: `Variant => ["alias" => tile, …] { behavior, fg, bg, script: include_str!(…) }`. The macro generates `enum Builtin { … }` and `impl Builtin { from_name, behavior, default_glyph_for, script }`. **To add a new builtin**: add one entry here + write `src/scripts/<name>.rhai`. No other code changes are needed — `TryFrom<&str>`, `behavior()`, `name()`, `default_glyph()`, the expansion pass, and the save round-trip all derive from the macro output. Current entries: `Gem` (`"gem"` → tile 4, blue ♦, solid + pushable + grab), `Heart` (`"heart"` → tile 3, red ♥, solid + pushable + grab — restores 1 health on grab), `Pusher` (`"pusher_north"` → 30, `"pusher_south"` → 31, `"pusher_east"` → 16, `"pusher_west"` → 17; gray arrow tiles, solid + unpushable), `Spinner` (`"spinner_cw"` → 47 `/`, `"spinner_ccw"` → 92 `\`; gray, solid + unpushable). All aliases in a family share one Rhai script; the script reads `Me.has_tag("BUILTIN_<alias>")` to determine per-instance direction/chirality.
+- `macro_rules! builtins!` — the declarative registry for script-backed archetypes. Each entry: `Variant => ["alias" => tile, …] { behavior, fg, bg, script: include_str!(…) }`. The macro generates `enum Builtin { … }` and `impl Builtin { from_name, behavior, default_glyph_for, script }`. **To add a new builtin**: add one entry here + write `src/scripts/<name>.rhai`. No other code changes are needed — `TryFrom<&str>`, `behavior()`, `name()`, `default_glyph()`, the expansion pass, and the save round-trip all derive from the macro output. Current entries: `Gem` (`"gem"` → tile 4, blue ♦, solid + pushable + grab), `Heart` (`"heart"` → tile 3, red ♥, solid + pushable + grab — restores 1 health on grab), `Pusher` (`"pusher_north"` → 30, `"pusher_south"` → 31, `"pusher_east"` → 16, `"pusher_west"` → 17; gray arrow tiles, solid + unpushable), `Spinner` (`"spinner_cw"` → 47 `/`, `"spinner_ccw"` → 92 `\`; gray, solid + unpushable). All aliases in a family share one Rhai script; the script reads `me.has_tag("BUILTIN_<alias>")` to determine per-instance direction/chirality.
 
 **`kiln-core/src/builtin_scripts.rs`** — tag helpers for script-backed archetypes (`pub(crate)`):
 - `BUILTIN_TAG_PREFIX` (`"BUILTIN_"`), `builtin_tag(arch) -> String`, `archetype_from_builtin_tag(tag) -> Option<Archetype>` — the tag convention. `expand_builtin_archetypes` tags each expanded object with `BUILTIN_<alias>` (e.g. `"BUILTIN_pusher_east"`) and also uses this string as the object's `script_name` compile-cache key (so each alias gets its own cached AST, though the Rhai source is the same for all aliases in a family). The script reads its tag to determine per-instance direction. `map_file::save` uses `archetype_from_builtin_tag` to collapse the object back into its archetype keyword so maps round-trip. The script sources and behavior definitions now live in `archetype.rs` via the `builtins!` macro (via `include_str!` of `scripts/*.rhai`); this file has only the three tag helpers.
@@ -34,7 +34,7 @@ The core types that were formerly monolithic in `game.rs` are now split into foc
 - `PortalDef { x, y, target_map, target_entry }` — parsed from map files, not yet runtime-wired.
 
 **`kiln-core/src/object_def.rs`** — scripted objects (`pub(crate)`):
-- `ObjectDef` — a scripted tile: `x`, `y`, `z: usize` (layer index, drives draw order), `glyph: Glyph`, `solid: bool` (default `true`), `opaque: bool` (default `true`), `pushable: bool` (default `false`), `grab: bool` (default `false`; set when a grab archetype like a gem is expanded — walking onto it fires `grab()`), `script_name: Option<String>`, `builtin_script: Option<&'static str>` (embedded source set when a script-backed archetype like a pusher is expanded at load; the expansion also sets `script_name` to a synthetic `BUILTIN_*` compile-key, so `builtin_script` supplies the *source* while `script_name` is the *key*; not serialized — see [`builtin_scripts`]), `tags: HashSet<String>`, `name: Option<String>`. The optional `name` is validated for board-wide uniqueness at load time; the first claimant keeps the name and any later duplicate has its name cleared to `None` (nonfatal). `ObjectDef::new(x, y)` constructs with defaults (`z = 0`). `ObjectDef::default_glyph()` returns tile 63 (`?`) yellow on black.
+- `ObjectDef` — a scripted tile: `id: ObjectId` (its stable id, assigned when the object is added to a board), `x`, `y`, `z: usize` (layer index, drives draw order), `glyph: Glyph`, `queue: ObjQueue` (its private output queue of pending [`Action`]s, drained onto the board queue between script calls — see `api::queue`), `solid: bool` (default `true`), `opaque: bool` (default `true`), `pushable: bool` (default `false`), `grab: bool` (default `false`; set when a grab archetype like a gem is expanded — walking onto it fires `grab()`), `script_name: Option<String>`, `builtin_script: Option<&'static str>` (embedded source set when a script-backed archetype like a pusher is expanded at load; the expansion also sets `script_name` to a synthetic `BUILTIN_*` compile-key, so `builtin_script` supplies the *source* while `script_name` is the *key*; not serialized — see [`builtin_scripts`]), `tags: HashSet<String>`, `name: Option<String>`. The optional `name` is validated for board-wide uniqueness at load time; the first claimant keeps the name and any later duplicate has its name cleared to `None` (nonfatal). `ObjectDef::new(x, y)` constructs with defaults (`z = 0`). `ObjectDef::default_glyph()` returns tile 63 (`?`) yellow on black.
 
 **`kiln-core/src/layer.rs`** — palette layers (the map-file/draw-stack unit):
 - `Layer { cells: Vec<(Glyph, Archetype)> }` (`pub(crate)`) — one row-major draw layer. A cell whose `glyph.tile == 0` (`Glyph::transparent()`) draws nothing, so the layer beneath shows through; solidity comes from the archetype, independent of transparency.
@@ -49,11 +49,11 @@ The core types that were formerly monolithic in `game.rs` are now split into foc
 - `solid_at(x, y) -> Option<Solid>` — the cell's single solid occupant (player checked first, then objects, then a solid terrain archetype on *any* layer via `solid_cell_layer`).
 - `is_passable(x, y)` — convenience inverse of `solid_at`.
 - `can_push(x, y, dir) -> bool` — read-only: does the chain of pushable solids end in open space?
-- `can_shift(x, y, dir) -> bool` — read-only, one cell ahead only: `(x, y)` holds a pushable *and* the next cell is empty or another pushable (does **not** require the chain to end in open space, unlike `can_push`). The right gate for a simultaneous shift/rotation via `apply_swap`. The **player** is always a blocker (a shift can't relocate it and `apply_swap` refuses to overwrite it).
+- `can_shift(x, y, dir) -> bool` — read-only, one cell ahead only: `(x, y)` holds a pushable *and* the next cell is empty or another pushable (does **not** require the chain to end in open space, unlike `can_push`). The **player** counts as a blocker for this check. A Rust-side companion read to `apply_shift`; not itself exposed to scripts.
 - `push(x, y, dir)` — mutating: shoves the chain one step, leaving a transparent cell behind (so a lower floor layer is revealed). A pushed solid moves within its own layer (found via `solid_cell_layer`).
 - `add_object(obj) -> ObjectId`, `remove_object(id) -> Option<ObjectDef>`, `object_ids_at(x, y)`, `solid_object_id_at(x, y)` — object add/remove + queries.
-- `grab_object_at(x, y) -> Option<ObjectId>` — a solid `grab` object on the cell (the player-walks-onto-it case). `GameState::try_move` uses it to fire `grab()` instead of bumping when the player steps onto a grab thing. Grab is **only** a player-movement event: a grab thing pushed/swapped into the player is treated as an ordinary solid (no special-case). (`remove_object` only edits the `objects` map; a live `ScriptHost` keeps a stale `ObjectRuntime` whose later host-fn calls resolve to a missing id and no-op — benign.)
-- `apply_swap(pairs: &[(i32,i32,i32,i32)]) -> Vec<LogLine>` — applies a batch of one-way solid moves **simultaneously** (reads every source's solid occupant — player/object/terrain — into a private `SolidSnapshot` before writing any destination, so cycles and two-cell swaps resolve). A source with no solid moves an "empty", removing the destination's solid (terrain cleared; a displaced object despawned via `remove_object`). The **player is never destroyed** — a write that would overwrite it without relocating it is skipped + logged (a grab object is no exception: it is refused like any other solid). Because a refused solid stays at its source cell, which another entry may also target, a final **overlap sweep** over the swapped cells keeps one solid per cell and deletes the rest (never the player), logging an error per deletion. Out-of-bounds entries are skipped + logged. Backs the script `swap()` fn.
+- `grab_object_at(x, y) -> Option<ObjectId>` — a solid `grab` object on the cell (the player-walks-onto-it case). `GameState::try_move` uses it to fire `grab()` instead of bumping when the player steps onto a grab thing. Grab is **only** a player-movement event: a grab thing pushed/shifted into the player is treated as an ordinary solid (no special-case). (`remove_object` deletes the object and its `ObjQueue` from the `objects` map; a live `ScriptHost` keeps an unused `Scope` for that id until it is rebuilt — harmless, since hook dispatch iterates the board's *current* ids.)
+- `apply_shift(cells: &[(i32, i32)]) -> Vec<LogLine>` — rotates the solids occupying a ring of cells one step: each cell's solid moves to the next coordinate in the list, and the last wraps back to the first. Backs the script `shift()` fn. A cell is **immobile** if its solid is unpushable, or is an `HCrate`/`VCrate` asked to move along its forbidden axis; immobility **cascades backward** along the ring (the cell that would feed an immobile cell is also held), so a blocked run stays put while the free tail still rotates. Movable cells are cleared, then each mover is `place`d at its target (a displaced object is despawned via `remove_object`). Any out-of-bounds coordinate **rejects the whole shift** (returned as a `LogLine`). The player rotates like any other solid.
 - `place_archetype(x, y, arch, glyph)` — editor stamp primitive (used by kiln-tui's drawing tools). Keyed only on the archetype, leaving any floor untouched: a non-`Empty` (solid) arch removes a solid object in the cell then writes `(glyph, arch)` into the existing terrain layer (`terrain_layer_at`, the single non-`Empty` cell) or else the top layer; `Empty` erases — removes every object plus the terrain cell (→ transparent `Empty`). Note it writes **terrain** even for script-backed archetypes (pushers/spinners), so the editor stamps an inert cell — see `expand_builtin_archetypes`.
 - `expand_builtin_archetypes()` — the **single** expansion point: replaces every `Archetype::Builtin(b, alias)` terrain cell with the scripted object it expands to. For each such cell: vacates the terrain slot (→ transparent `Empty`), calls `b.script()` for the embedded source, uses `builtin_tag(arch)` as both the `BUILTIN_<alias>` tag and the `script_name` compile-cache key, and copies the cell's glyph (so palette overrides survive). The object's `pushable`/`grab` flags come from `b.behavior()`. Idempotent (vacated cells become `Archetype::Empty`, so a second pass finds nothing). Called by `TryFrom<MapFile> for Board` after cross-layer validation (disk loads) and again by the editor's `playtest()` on the `World::deep_clone` (so editor-stamped machines, which `place_archetype` writes as inert terrain, also run). Builtin objects get ids after hand-placed ones (layer-then-reading order among themselves).
 - `in_bounds((i32, i32))` — bounds-checks a possibly-negative coord.
@@ -70,13 +70,14 @@ The core types that were formerly monolithic in `game.rs` are now split into foc
 - `SpeechBubble { object_id, text, remaining }` — an active speech bubble created by a script's `say(s)` call. `remaining` counts down in `GameState::tick`; when it reaches zero the bubble is removed. At most one bubble per object (a new `say()` replaces the old one).
 - `SAY_DURATION: f64` — how long a bubble lives (3.0 seconds).
 - `Scroll { source: ObjectId, lines: Vec<ScrollLine> }` — an active scroll overlay opened by a script's `scroll(lines)` call. Lives on `GameState::active_scroll: Option<Scroll>`; front-ends pause ticks while it's `Some` and close it via `close_scroll(choice)`. `ScrollLine` is re-exported from `action.rs` through `game.rs` so front-ends import both from `kiln_core::game`.
-- `GameState` — owns `world: World` (all boards as `Rc<RefCell<Board>>` + world scripts) and `current_board_name: String` (key of the active board). `pub log: Vec<LogLine>`, `scripts: ScriptHost`, `pub speech_bubbles: Vec<SpeechBubble>`, `pub active_scroll: Option<Scroll>`, and `pub player: Player` — the game-global player state ([`player::Player`]: `health`/`max_health`/`gems`/`keys`) that persists across board transitions (it is *not* per-board; `Board::player` holds only the per-board `PlayerPos`). `player.gems` is changed at runtime by the `add_gems(n)` script fn (e.g. grabbing a gem); `player.health` is changed by `alter_health(dh)` (clamped to `[0, max_health]`, e.g. grabbing a heart); `player.keys` is changed by `set_key(color, present)`. Each script-hook call is handed a snapshot of `player` wrapped in a `ScriptState` bundle (read-only, exposed to Rhai as the `Player` constant — see `script.rs`). Front-ends reach the active board through `board() -> Ref<Board>` / `board_mut() -> RefMut<Board>` (both look up `world.boards[current_board_name]`). `current_board_name() -> &str` returns the active key. **`from_world(world: World) -> Self`** is the primary constructor: clones the start board's `Rc<RefCell<Board>>` for the `ScriptHost`, compiles scripts from `world.scripts`. `new(board)` and `with_scripts(board, scripts)` are `#[cfg(test)]`-only sugar that build a minimal single-board `World`. `try_move(dir)` moves the player (pushing if possible) and fires `bump(-1)` on any solid object walked into; walking onto a `grab` thing (via `Board::grab_object_at`) instead moves onto it and fires `grab()` + an immediate `resolve()` so its `die()`/`add_gems()`/`alter_health()` apply before the call returns (no player+object overlap). **`try_move` is the only grab trigger** — a grab thing pushed or swapped into the player is an ordinary solid (it slides/blocks/refuses like any other). `run_init()` runs object `init()` hooks once at startup. `tick(dt)` advances cooldowns, expires speech bubbles, and runs `tick(dt)` hooks every frame. Both end by calling `resolve()`, which drains the board queue and applies each `Action` (`Log` → `log`, `SetTile` → source glyph, `Move(dir)` → `step_object`, `Say` → `speech_bubbles`, `Scroll` → `active_scroll`, `AddGems(n)` → `player.gems`, `AlterHealth(dh)` → `player.health` clamped to `[0, max_health]`, `Die` → `remove_object(source)`). Resolution is two-phase: mutate the board collecting `(bumped, bumper)` pairs, drop the borrow, then fire `run_bump` for each pair. `drain_errors()` moves script errors into `log`. `close_scroll(choice)` clears `active_scroll` and optionally fires `run_send(source, choice, None)` to dispatch the player's selection back to the object.
+- `GameState` — owns `world: World` (all boards as `Rc<RefCell<Board>>` + world scripts) and `current_board_name: String` (key of the active board). `pub log: Vec<LogLine>`, `scripts: ScriptHost`, `pub speech_bubbles: Vec<SpeechBubble>`, `pub active_scroll: Option<Scroll>`, and `pub player: Player` — the game-global player state ([`player::Player`]: `health`/`max_health`/`gems`/`keys`) that persists across board transitions (it is *not* per-board; `Board::player` holds only the per-board `PlayerPos`). `player.gems` is changed at runtime by the `add_gems(n)` script fn (e.g. grabbing a gem); `player.health` is changed by `alter_health(dh)` (clamped to `[0, max_health]`, e.g. grabbing a heart); `player.keys` is changed by `set_key(color, present)`. Each script-hook call is handed a `ScriptState` bundle — a `Copy` snapshot of `player` plus a shared handle to the active board — passed to the hook as its `state` parameter (Rhai type `State`, read via `state.player`/`state.board`; see `api::state`). Front-ends reach the active board through `board() -> Ref<Board>` / `board_mut() -> RefMut<Board>` (both look up `world.boards[current_board_name]`). `current_board_name() -> &str` returns the active key. **`from_world(world: World) -> Self`** is the primary constructor: clones the start board's `Rc<RefCell<Board>>` for the `ScriptHost`, compiles scripts from `world.scripts`. `new(board)` and `with_scripts(board, scripts)` are `#[cfg(test)]`-only sugar that build a minimal single-board `World`. `try_move(dir)` moves the player (pushing if possible) and fires `bump(-1)` on any solid object walked into; walking onto a `grab` thing (via `Board::grab_object_at`) instead moves onto it and fires `grab()` + an immediate `resolve()` so its `die()`/`add_gems()`/`alter_health()` apply before the call returns (no player+object overlap). **`try_move` is the only grab trigger** — a grab thing pushed or swapped into the player is an ordinary solid (it slides/blocks/refuses like any other). `run_init()` runs object `init()` hooks once at startup. `tick(dt)` advances cooldowns, expires speech bubbles, and runs `tick(dt)` hooks every frame. Both end by calling `resolve()`, which drains the board queue and applies each `Action` (`Log` → `log`, `SetTile`/`SetColor` → source glyph, `Move(dir)` → `step_object`, `Say` → `speech_bubbles`, `Scroll` → `active_scroll`, `AddGems(n)` → `player.gems`, `AlterHealth(dh)` → `player.health` clamped to `[0, max_health]`, `SetKey` → `player.keys`, `Shift` → `apply_shift`, `Push`/`Teleport` → board moves, `Send` → `run_send`, `Die` → `remove_object(source)`). Resolution is two-phase: mutate the board collecting `(bumped, bumper)` pairs, drop the borrow, then fire `run_bump` for each pair. `drain_errors()` moves script errors into `log`. `close_scroll(choice)` clears `active_scroll` and optionally fires `run_send(source, choice, None)` to dispatch the player's selection back to the object.
 
-**`kiln-core/src/action.rs`** — the `Action` enum and its Rhai-facing conversion:
+**`kiln-core/src/action.rs`** — the `Action` enum and its supporting types:
 - `MOVE_COST: f64` — how long a move occupies an object before it can act again (0.25 s).
 - `ScrollLine` (`pub`) — one line of content in a `Scroll` action: `Text(String)` (plain, word-wrapped) or `Choice { choice, display }` (selectable; `choice` is sent back to the source object when the player picks it).
-- `Action` (`pub(crate)`) — deferred mutation emitted by a script and applied by `GameState` after promotion onto the board queue: `Move(Direction)`, `SetTile(u32)`, `Log(LogLine)`, `SetTag { target, tag, present }`, `Say(String)`, `Delay(f64)` (never reaches the board queue — consumed by `ScriptHost::drain` to pace the object), `SetColor { fg, bg }`, `Send { target, fn_name, arg }`, `Scroll(Vec<ScrollLine>)`, `Teleport { x, y }`, `Push { x, y, dir }` (shove a chain at arbitrary coords; zero time cost), `Swap(Vec<(i32,i32,i32,i32)>)` (batch of simultaneous one-way solid moves; zero time cost), `AddGems(i64)` (change `GameState::player.gems`, clamped at 0; zero cost), `AlterHealth(i64)` (change `GameState::player.health`, clamped to `[0, max_health]`; zero cost), `Die` (remove the source object; zero cost).
-- `action_to_map(action) -> rhai::Map` — converts an `Action` to a Rhai map for `Queue.peek()` / `Queue.pop()`. The map always has a `"type"` key; other keys carry the payload. `Scroll`/`Swap` emit `type` only (their payloads are not inspectable via the map API). `Log` is flattened to its first span's text.
+- `SendArg` — the optional argument carried by a `Send` action / `send()` call: `None`/`Int`/`Float`/`String`, with `From<Dynamic>`/`Into<Dynamic>` conversions.
+- `Action` (`pub(crate)`) — deferred mutation emitted by a script and applied by `GameState` after promotion onto the board queue: `Move(Direction)`, `SetTile(u32)`, `Log(LogLine)`, `SetTag { target, tag, present }`, `Say(String, f64)` (bubble text + duration), `Delay(f64)` (never reaches the board queue — consumed by `ObjQueue::drain` to pace the object), `SetColor { fg, bg }`, `Send { target, fn_name, arg }`, `Scroll(Vec<ScrollLine>)`, `Teleport { x, y }`, `Push { x, y, dir }` (shove a chain at arbitrary coords; zero time cost), `Shift(Vec<(i64,i64)>)` (rotate the solids on a ring of cells one step; zero time cost), `AddGems(i64)` (change `GameState::player.gems`, clamped at 0; zero cost), `AlterHealth(i64)` (change `GameState::player.health`, clamped to `[0, max_health]`; zero cost), `SetKey(String, bool)` (give/take a named player key color; zero cost), `Die` (remove the source object; zero cost).
+- `BoardAction { source, action }` — an `Action` promoted onto the board queue, tagged with the `ObjectId` that issued it.
 
 **`kiln-core/src/floor.rs`** — procedural floor generators:
 - A "floor" is just a non-solid, visible `Empty` cell on a layer (a palette entry with `kind = "floor"`). This module only owns the generators; the actual per-cell placement happens in `layer.rs` during load.
@@ -85,15 +86,25 @@ The core types that were formerly monolithic in `game.rs` are now split into foc
 **`kiln-core/src/log.rs`** — styled log messages:
 - `LogSpan { text, fg: Option<Rgba8>, bg: Option<Rgba8> }` and `LogLine { spans: Vec<LogSpan> }` — a UI-agnostic styled message (colors are core `Rgba8`, not a front-end type). `LogLine::raw()`, a chainable `push()`, `append()`, and `LogLine::error()` (a red-on-black single-span constructor used for nonfatal load errors) build messages; each front-end converts a `LogLine` to its own styled text at render time.
 
-**`kiln-core/src/script.rs`** — Rhai scripting runtime:
-- `ScriptHost` — owns the Rhai `Engine`, the compiled scripts referenced by a board's objects, a per-object persistent `Scope` + output queue + ready timer, and the shared board queue. Built with `ScriptHost::new(&Rc<RefCell<Board>>, &HashMap<String, String>)`: the first arg is a shared ref to the active board (used by read-API closures), the second is the world-level script pool. Each object resolves to a `(key, source)` compiled once per key: the key is the object's `script_name` (a world-pool name for a named script, or a synthetic `BUILTIN_*` name assigned by `expand_builtin_archetypes` so identical built-ins, e.g. all pushers, share one AST); the source is the pool entry for that name, or the object's embedded `builtin_script` when present. Reports compile/unknown-script failures onto the error sink; runs nothing.
-- Lifecycle hooks per object: `init()` (zero-arg), `tick(dt)` (elapsed seconds as `f64`), `bump(id)` (the bumper's `ObjectId`, or `-1` for the player), and `grab()` (zero-arg; fired when the player walks onto a `grab` thing — the only grab trigger), all optional — detected via `AST::iter_functions()` by name and arity. Driven by `run_init(state)` / `run_tick(state, dt)` / `run_bump(state, object_id, bumper)` / `run_grab(state, object_id)` — each takes a `ScriptState(pub Player)` bundle (a `Copy` wrapper that exists so more host context can be threaded through later without re-touching every signature); the host pulls its `Player` out and sets it into the object's scope as the `Player` constant before the call; runtime errors go to the error sink (drained to the log), not fatal.
-- **Reads (direct):** read getters (`player_x`, `player_y`, `width`, `height`) are registered on `Rc<RefCell<Board>>` (the `BoardRef` alias, exposed to Rhai under the type name `Board`) — getters only, so read-only by construction. A clone of the handle is pushed into each scope as the constant `Board`. The player's game-global stats are likewise exposed read-only as the `Player` constant (a `Copy` snapshot, carried in by the `ScriptState` bundle and set into scope before each hook call; getters `Player.gems`, `Player.health`, `Player.max_health` — keys not yet exposed), via `register_player_type`. `blocked(dir) -> bool` is also a read fn: true if the caller's target cell is off-board, already solid, or the destination of a pending move on the board queue (an object never sees its *own* move, which is pumped only after its script returns). `can_push(x, y, dir) -> bool` is a read fn mirroring `Board::can_push`: true if `(x, y)` holds a pushable whose chain can be shoved in `dir` (false off-board). `can_shift(x, y, dir) -> bool` mirrors `Board::can_shift`: like `can_push` but only checks the single cell ahead (pushable source + an empty-or-pushable next cell), the right gate for a simultaneous shift/rotation via `swap`. `passable(x, y) -> bool` mirrors `Board::is_passable`: true if `(x, y)` is on-board and holds no solid (off-board → false), letting a script tell a hole apart from a blocked solid (which `can_shift`/`can_push` alone cannot). `has_tag(s) -> bool` and `get_tags() -> Array` read the calling object's tag set; `objects_with_tag(s) -> Array` returns all object ids carrying that tag. `my_name() -> String` returns the calling object's name (or `""` if unnamed); `object_id_for_name(s) -> i64` looks up an object by name and returns its id, or `0` if not found. Each getter briefly borrows the shared `Board`.
-- **Actions & rate limiting (two-tier queues):** host fns `move(dir)`, `set_tile(n)`, `log(s)`, `say(s)`, `scroll(lines)`, `push(x, y, dir)`, `swap(pairs)`, `add_gems(n)` (adjust the player's gem count), `alter_health(dh)` (adjust the player's health, clamped to `[0, max_health]`), `die()` (remove the calling object) append an `Action` (`Move`/`SetTile`/`Log`/`Say`/`Scroll`/`Push`/`Swap`; `MOVE_COST = 0.25` s for `Move`, else 0 — `push`/`swap` add no delay) to the *issuing object's* output queue (routed by the per-call tag via a `HashMap<usize, ObjQueue>`). `scroll(lines)` takes a Rhai array where each element is a string (text line) or a two-element array `[choice_key, display_text]` (selectable choice). `push(x, y, dir)` shoves the pushable chain at arbitrary coords `(x, y)`. `swap(pairs)` takes an array of four-int `[src_x, src_y, dst_x, dst_y]` arrays (a malformed entry is skipped + logged) and moves all the named solids simultaneously (see `Board::apply_swap`). `ScriptHost::pump(i)` promotes ready actions onto the shared **board queue** (`Vec<BoardAction { source, action }>`): the leading run of zero-cost actions plus at most one timed action, which arms that object's **ready timer** and ends the pump. While a ready timer is `> 0` nothing is pulled (this caps object speed); `advance_timers(dt)` counts them down each frame. `GameState` drains the board queue with `take_board_queue()` and applies it after the batch — so scripts mutate without a `&mut GameState` borrow. Errors (compile/runtime) bypass the queues via the error sink (`take_errors()`).
-- The `Queue` object (a handle to the calling object's output queue) is pushed into each scope; scripts call `Queue.length()`, `Queue.clear()`, `Queue.peek()` (front action as a Rhai map, or `()` if empty), and `Queue.pop()` (same, removes the front). Safe to mutate from script because the host only touches output queues between calls (during `pump`).
-- **Sender identity:** `source` (which object issued an action) rides the per-call **tag** — `run` calls `call_fn_with_options(...with_tag(object_id)...)` and the host fns read it via `NativeCallContext::tag()` (decoded back to an `ObjectId` by `source_of`). Scripts write `move(North)` without naming themselves; `North`/`South`/`East`/`West` are `Direction` constants in scope, and `impl From<Direction> for (i32,i32)` gives the delta.
+**`kiln-core/src/script.rs`** — Rhai scripting **host** (the script-facing types live in `kiln-core/src/api/`, below). The script-author's reference is [`docs/script-api.md`](../docs/script-api.md).
+- `Registerable` trait — `fn register(engine, error_sink)`: a type's hook for installing itself (Rhai type name + getters/methods) on the `Engine`. Implemented by every `api` type plus `Glyph`/`Keyring`.
+- `ScriptHost` — owns the Rhai `Engine`, the compiled scripts (`HashMap<String, CompiledScript>`), one persistent `Scope` per scripted object (`HashMap<ObjectId, Scope>`), the shared board queue, and the error sink. Built with `ScriptHost::new(&Rc<RefCell<Board>>, &HashMap<String, String>)`: the first arg is a shared ref to the active board (cloned into the write-API closures and each scope's `Registry`), the second is the world-level script pool. Each script is compiled once per `script_key` (the object's `script_name` — a world-pool name, or a synthetic `BUILTIN_*` name assigned by `expand_builtin_archetypes` so identical built-ins share one AST); the source is the pool entry for that key, or the object's embedded `builtin_script`. `CompiledScript` records which hooks the AST defines (`has_init`/`has_tick`/`has_bump`/`has_grab`). **Per-object output queues no longer live here** — each `ObjectDef` owns its `queue: ObjQueue`. Reports compile/unknown-script failures onto the error sink; runs nothing.
+- Lifecycle hooks, each taking `me` (an `ObjectInfo`) and `state` (a `ScriptState`) before any hook-specific arg: `init(me, state)`, `tick(me, state, dt)`, `bump(me, state, id)` (the bumper's `ObjectId`, or `-1` for the player), and `grab(me, state)` (fired when the player walks onto a `grab` thing — the only grab trigger). All optional — detected via `AST::iter_functions()` by name **and arity** (2/3/3/2). Driven by `run_init(state)` / `run_tick(state, dt)` / `run_bump(state, id, bumper)` / `run_grab(state, id)`, all funneling through `run_hook_on_one`: it builds a fresh `ObjectInfo` for the object, pushes `[me, state, (arg)]`, and calls the hook tagged with the object's id. After the call — **whether or not the hook is defined** — it always drains the object's queue, so a delay still advances on an object that has no `tick`. Runtime errors go to the error sink (drained to the log), not fatal.
+- `run_send(state, id, fn_name, arg)` — calls an arbitrary named function on an object (backs the `send()` action and scroll-choice dispatch). Picks the param list by the function's arity: 3 → `(me, state, arg)`, 2 → `(me, state)`, 1 → `(arg)`, 0 → `()`; a missing arg is `Dynamic::UNIT`. Errors if no function of that name exists.
+- **Reads** are methods/getters on the `api` types handed to the hook — `state.player.*`, `state.board.*`, `me.*` (see the `api/` section). There are **no read free functions** anymore.
+- **Write API** (`register_write_api`) — free functions that enqueue an `Action` onto the **issuing object's** `queue` (resolved from the per-call tag): `move(dir)` (enqueues `Move` then a `MOVE_COST` delay), `delay(secs)`/`now()` (queue pacing), `set_tile(n)`, `set_fg`/`set_bg`/`set_color`, `set_tag(target, tag, present)`, `log(s)`, `say(s)`/`say(s, dur)`, `scroll(lines)`, `send(target, fn [, arg])`, `teleport(x, y)`, `push(x, y, dir)`, `shift([[x, y], …])`, `add_gems(n)`, `alter_health(dh)`, `set_key(color, present)`, `die()`. `scroll(lines)` takes a Rhai array whose elements are a string (text line) or a two-element `[choice_key, display_text]` (selectable choice). `shift` takes an array of two-int `[x, y]` arrays (a malformed entry logs an error) and rotates that ring of cells via `Board::apply_shift`.
+- **Queue draining (two-tier):** each object's actions sit in its own `ObjQueue` until `ObjectInfo::drain(board_queue, dt)` promotes them onto the shared **board queue** (`Vec<BoardAction>`): it first eats leading `Delay` actions with `dt` (a delay longer than `dt` is decremented and stops the drain — this caps object speed), then moves the run of ready actions across. `GameState` takes the board queue with `take_board_queue()` and applies it after the batch, so scripts mutate without a `&mut GameState` borrow. Errors bypass the queues via the error sink (`take_errors()`).
+- **Constants in scope:** only `Registry` is pushed into each object's scope (the `me`/`state` views are hook *parameters* now). `register_global_constants` registers the `North`/`South`/`East`/`West` `Direction` values and the 16 named colors as a **global module**, visible at any call depth (including Rhai→Rhai calls and helper functions) — unlike scope constants such as `Registry`.
+- `Registry` (a `Board`-handle wrapper) — `Registry.get(key)` / `set(key, value)` / `get_or(key, default)` read and write the board's `registry: HashMap<String, RegistryValue>`, which **persists across board transitions**. `set(key, ())` removes a key; unsupported value types are ignored; `get_or` only returns the stored value when it matches the default's Rhai type.
+- **Sender identity uses stable ids:** the issuing `ObjectId` rides the per-call **tag** — `run_*` calls `call_fn_with_options(...with_tag(id)...)` and the write fns read it via `NativeCallContext::tag()` (decoded by `source_of`; id 0, never valid, is the no-source fallback). It matches `Board::objects`' `BTreeMap` keys, so it survives object spawn/destroy/reorder.
 - `GameState` (hence the `Engine`/`Scope`) is single-threaded / not `Send`; fine for kiln-tui.
-- **Sender identity uses stable ids:** `BoardAction.source`, `ObjectRuntime.object_id`, and the `QueueMap` keys are all the object's `ObjectId` (matching `Board::objects`' `BTreeMap` keys), so they survive object spawn/destroy/reorder. The per-call tag carries the id as an `i64` (id 0 — never valid — is the no-source fallback). `ScriptHost::objects` is still a `Vec<ObjectRuntime>` built by iterating the board map, so it stays in ascending-id order.
+
+**`kiln-core/src/api/`** — the Rhai **script API**: the types scripts actually touch, each implementing `script::Registerable`. Split out of `script.rs` so the host (engine/queues/dispatch) and the script-facing surface can evolve separately. (Author-facing reference: [`docs/script-api.md`](../docs/script-api.md).)
+- `api::state` — `ScriptState { player: PlayerWithPos, board: BoardRef }` (Rhai type **`State`**), the `state` parameter of every hook. `from_game_state` snapshots the player and clones the board handle; getters `state.player` / `state.board`.
+- `api::player` — `PlayerWithPos(Player, PlayerPos)` (Rhai type **`Player`**), a `Copy` bundle of the game-global `Player` stats and the per-board `PlayerPos` so they register as one Rhai object. Getters `gems`, `health`, `max_health`, `keys` (a `Keyring`, exposing one `bool` getter per color), `x`, `y`.
+- `api::board` — `BoardRef = Rc<RefCell<Board>>` (Rhai type **`Board`**), a read-only handle. Getters `width`/`height`; methods `can_push(x, y, dir)`, `passable(x, y)`, `get(id)` (→ `ObjectInfo` or `()`; `id <= 0` logs an error), `named(name)` (→ `ObjectInfo` or `()`), `tagged(tag)` (→ array of `ObjectInfo`).
+- `api::object_info` — `ObjectInfo` (a snapshot of one object: `id`, `x`, `y`, a board handle, `script_name`, and a clone of the object's `ObjQueue`), used as both the `me` parameter and the return type of the `Board` lookups (so self and other objects are the **same** type). Getters `x`/`y`/`id`/`name`/`tags`/`glyph`/`waiting`/`queue`; methods `has_tag(tag)`, `delay(secs)`, `can_push(dir)`, `blocked(dir)`. `from_id`/`from_def` build it; `drain(target, dt)` promotes the underlying object's queued actions onto the board queue.
+- `api::queue` — `ObjQueue(Rc<RefCell<VecDeque<Action>>>)` (Rhai type **`Queue`**), one object's output queue, owned by its `ObjectDef` and reachable as `me.queue`. Rhai surface: getter `length`, methods `clear()`, `delay(secs)`. Rust surface used by the host: `act`, `delay` (merges a trailing delay), `now` (promote the last-enqueued action to the front), `drain` (eat leading delays by `dt`, then promote ready actions), `waiting` (front is a `Delay`).
 
 **`kiln-core/src/map_file.rs`** — per-board serde shell + load/save orchestration (the bulk of the per-layer work lives in `layer.rs`):
 - `MapFile { map: MapHeader, layers: Vec<LayerData> }` — serde for one board: a `[map]` header (`name`, `width`, `height`, optional `board_script_name`; **no** `player_start` — the player is a `kind = "player"` palette char) plus the `[[layers]]` stack. Does **not** include scripts (those live in `World::scripts`).