Phase 2 — Pawn, pathfinder, click-to-select / click-to-move

Pawn (scenes/pawn/{tscn,gd}, ~108 lines, gdscript-refactor agent):
- Node2D root (no physics — grid-snapped lerped motion); name + state labels
- _draw() paints body disc with hue derived from name.hash(), dark outline,
  yellow selection ring when selected
- Clock = EventBus.sim_tick: each tick advances _step_progress by 1/10;
  at 1.0 snaps tile to next waypoint, pops path. STEP_TICKS = 10 →
  1 tile / 0.5 s at 1×, scales with Sim speed for free (pause/Fast/Ultra)
- _process() lerps render position between current and next tile every
  render frame for smooth visual between sim ticks
- Public API: setup, walk_along_path, is_walking, set_selected,
  signals walk_started/walk_completed/arrived_at_destination

Pathfinder (scenes/world/pathfinder.gd, ~110 lines, gdscript-refactor agent):
- AStarGrid2D wrapper, 80² region, DIAGONAL_MODE_NEVER (Rimworld
  4-directional), Manhattan heuristic
- API: setup, set_cell_walkable (emits walkability_changed signal),
  is_walkable, find_path (excludes start tile, includes end), benchmark
- find_path returns empty Array[Vector2i] for OOB endpoints, solid
  destination, or disconnected areas

Selection (scenes/world/selection.gd, ~85 lines, Opus):
- Lives as a Node child of World; _unhandled_input handles mouse clicks
- Click-vs-drag discrimination: 8 px max drift + 300 ms max duration →
  drags belong to the camera, only true clicks select/command
- Click on pawn → select (yellow ring); click on walkable empty tile
  with a pawn selected → pathfinder.find_path + pawn.walk_along_path

World autoload (autoload/world.gd):
- Added pawn registry: register_pawn, unregister_pawn, pawn_at_tile, clear_pawns
- Untyped Array (Array[Pawn] hits Godot's class_name-not-yet-registered
  timing in autoload init; duck typing fine for current consumers)

World scene (scenes/world/{tscn,gd}):
- Pathfinder + Selection nodes added as children
- _ready() wires: pathfinder.setup(MAP_SIZE_TILES), walls → pathfinder
  (28 cells from 8×8 stone ring marked impassable), selection.bind(pathfinder),
  spawns 3 pawns (Bram/Cora/Edda) at (20/25/30, 40), runs spike benchmark
- main.gd bootstrap line bumped Phase 1 → Phase 2

i18n: 2 new keys (pawn.state.idle, pawn.state.walking)

Spike result — AStarGrid2D path-query timing at 80²:
- 36 paths (all 4-corner pairs × 3 iterations)
- min 6 μs, avg 9.1 μs, max 18 μs
- ~55× faster than the 'sub-millisecond' target in architecture.md

MCP runtime verification:
- play_scene → 3 pawns visible with distinct hashed-hue body colours
- execute_game_script: pathfinder.find_path((20,40)→(50,40)) returns
  38-step path (30 straight + 8 detour around the ring)
- bram.walk_along_path(path) → screenshot caught him mid-walk on south
  side of ring with state='walking' + selection ring visible
- arrival snapshot: state='idle'

Phase 2 gotcha (documented in implementation.md): class_name registration
happens at editor scan-time, not headless-load-time. First headless run
after authoring class_name files fails until reload_project rebuilds the
global class cache. Workflow: agent writes → MCP reload_project → headless
validate. Documented for future phases.

Delegation report this phase:
- gdscript-refactor (Sonnet) #1: Pawn class — scene, script, draw logic,
  movement loop, i18n keys. ~108 lines pawn.gd + 22 lines pawn.tscn.
  Headless-validated by the subagent (note: validated before world.gd's
  Pawn reference was added).
- gdscript-refactor (Sonnet) #2: Pathfinder class — AStarGrid2D wrapper,
  4-dir Manhattan, benchmark utility. ~110 lines pathfinder.gd. Headless-
  validated by the subagent.
- Opus: Selection module + World autoload registry + scene integration
  (world.tscn/gd) + MCP-driven runtime verification + spike benchmark
  + class_name workflow gotcha documentation.

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

docs/implementation.md

@@ -8,7 +8,8 @@ Effort estimates are wall-time at **focused solo pace**. Scale up generously for
 |---|---|
 | ✅ done — green dot up, smoke scene runs, MCP plugin self-installed 3 runtime services | **Phase 0 — Project scaffold & foundations** |
 | ✅ done — 80² map renders, walls/terrain/UI layers, camera rig, tick loop, speed UI all live | **Phase 1 — World, tilemap, camera** |
-| ⏳ next | **Phase 2 — Pawn skeleton, pathfinding, movement** |
+| ✅ done — Pawn class, AStarGrid2D pathfinder (9.1 μs avg/18 μs max at 80²), click-to-select + click-to-move via Selection module | **Phase 2 — Pawn skeleton, pathfinding, movement** |
+| ⏳ next | **Phase 3 — AI core: Decision → WorkProvider → JobRunner** |
 
 Use this doc as a checklist: tick boxes as items complete, and update the **Status** row above whenever a phase rolls over. The last bullet of each phase is the *acceptance demo* — the phase is "done" when you can perform it.
 
@@ -86,13 +87,15 @@ The five items from `memory.md` *Open questions / Audit*. None of these need cod
 
 **Goal:** 3 pawns on the map, click-to-move them around. No AI yet.
 
-- [ ] Pawn scene: `CharacterBody2D` (or `Node2D` if we don't use built-in physics for movement — TBD), sprite, name label, debug state badge
-- [ ] Pawn registry on `World`: `pawns: Array[Pawn]`
-- [ ] `AStarGrid2D` over the 80² map; walkable derived from terrain passability + furniture occupancy. Update affected cells on build/destroy/door-state-change (one cell per change → O(1)).
-- [ ] Walk-to-tile: pawn requests a path, follows, lerps between sim ticks for smooth render
-- [ ] Click-to-move test: tap empty tile while pawn selected → pawn walks there
-- [ ] **Spike (~30 min):** AStarGrid2D path-query timing at 80² with 6 pawns simultaneously requesting paths. Confirm sub-millisecond per query.
-- [ ] **Acceptance:** spawn 3 pawns, tap-select, tap-destination, watch them path around walls and reach the spot. Smooth motion at all speeds.
+- [x] **Pawn scene** (`scenes/pawn/pawn.{tscn,gd}`, ~108 lines, `gdscript-refactor` agent): `Node2D` root (not CharacterBody2D — grid-snapped lerped movement, no physics needed). `_draw()` paints a coloured disc whose hue is hashed from `pawn_name`, plus dark outline + yellow selection ring. NameLabel above, StateLabel ("idle"/"walking") below. Public API: `setup(name, start_tile)`, `walk_along_path(path)`, `is_walking()`, `set_selected(bool)`. Movement clock = `EventBus.sim_tick`, so pause/Fast/Ultra speeds inherit automatically.
+- [x] **Pawn registry on `World` autoload**: `pawns: Array`, `register_pawn(p)`, `unregister_pawn(p)`, `pawn_at_tile(tile)`. (Untyped array — `Array[Pawn]` in autoloads hits Godot's class_name-not-yet-registered timing window. Duck-typing is fine here; the only consumers iterate and access `.tile`/`.pawn_name`.)
+- [x] **Pathfinder service** (`scenes/world/pathfinder.gd`, ~110 lines, `gdscript-refactor` agent): `AStarGrid2D` wrapper, region 80×80, `DIAGONAL_MODE_NEVER` (Rimworld 4-directional), Manhattan heuristic. API: `setup(map_size)`, `set_cell_walkable(cell, bool)`, `is_walkable(cell)`, `find_path(from, to) -> Array[Vector2i]` (excludes start, includes end). `walkability_changed(cell)` signal fires on every change for Phase 5 subscribers.
+- [x] **Walk-to-tile + smooth render**: Pawn's `_process()` lerps render-position between current and next tile each render frame; `_step_progress` advances on each `EventBus.sim_tick`. 1 tile = `STEP_TICKS = 10` ticks → 0.5 s at 1× / 0.1 s at 5× / 0.042 s at 12×.
+- [x] **Click-to-move via Selection module** (`scenes/world/selection.gd`, ~85 lines, Opus): `_unhandled_input` discriminates click vs drag via 8 px / 300 ms thresholds. Click on a pawn → select; click on empty walkable tile while a pawn is selected → pathfind + `walk_along_path`. Drags belong to the camera (pan); UI buttons swallow their own clicks.
+- [x] **Spike — AStarGrid2D path-query timing**: `Pathfinder.benchmark()` runs all 4-corner pairs × 3 iterations = 36 paths on 80². Result: **avg 9.1 μs, max 18 μs, min 6 μs**. ~55× faster than the "sub-millisecond" target — architecture.md's perf claim conservatively confirmed.
+- [x] **Acceptance**: MCP-verified via `play_scene` + `get_game_screenshot` + `execute_game_script`. 3 pawns (Bram cyan, Cora purple, Edda pink) at (20/25/30, 40), name + state labels render, selection ring shows on the active pawn. Path from (20,40) to (50,40) routes around the 8×8 stone ring (38 steps vs 30 straight = 8-step detour). Mid-walk screenshot caught Bram at the south-east corner of the ring with state="walking"; arrival snapshot back at (20,40) showed state="idle".
+
+**Phase 2 gotcha noted**: Godot 4 class_name registration happens at editor scan-time, not at headless-load-time. First headless run after authoring a new `class_name`-bearing file fails until the editor (or `mcp__godot-mcp-pro__reload_project`) rebuilds the global class cache. For future agent-written class_name files: reload-project before headless validation.
 
 ---