SCUMM-style web adventure engine v0.1

Headless, data-driven core (no DOM, no eval): loader with one-pass
validation, verb-coin interaction resolution, polygon walkables with
Dijkstra pathfinding, branching dialogue with mid-conversation saves,
declarative JSON conditions/effects, versioned JSON saves.

Thin integration layer: asset manifest with graceful placeholders,
WebAudio music loop points (midi-playlist convention), canvas renderer
(hotspot boxes drawn where hitTest clicks), HUD model.

Web harness (web/) + skeleton example game exercising every feature.
69 tests (node --test), tools/run_all.sh gate, docs/SPEC.md design spec.
Verified end-to-end in a real browser: intro scene, walking, look/take,
room exits, dialogue choices.

tests/walkable.test.js

@@ -0,0 +1,58 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { pointInPolygon, nearestPointInPolygon, WalkArea } from "../src/core/walkable.js";
+
+const square = [[0, 0], [100, 0], [100, 100], [0, 100]];
+
+test("point in polygon", () => {
+  assert.equal(pointInPolygon([50, 50], square), true);
+  assert.equal(pointInPolygon([150, 50], square), false);
+  const tri = [[0, 0], [100, 0], [50, 100]];
+  assert.equal(pointInPolygon([50, 90], tri), true);
+  assert.equal(pointInPolygon([5, 90], tri), false);
+});
+
+test("nearest point clamps to boundary", () => {
+  const p = nearestPointInPolygon([150, 50], [square]);
+  assert.deepEqual(p, [100, 50]);
+});
+
+test("walk area contains/clamp", () => {
+  const wa = new WalkArea([square]);
+  assert.equal(wa.contains([10, 10]), true);
+  assert.deepEqual(wa.clamp([150, 50]), [100, 50]);
+  assert.deepEqual(wa.clamp([10, 10]), [10, 10]);
+});
+
+test("straight path inside one polygon", () => {
+  const wa = new WalkArea([square], { sampleStep: 20 });
+  const path = wa.path([10, 50], [90, 50]);
+  assert.ok(path, "path found");
+  assert.deepEqual(path[0], [10, 50]);
+  assert.deepEqual(path.at(-1), [90, 50]);
+});
+
+test("path between two polygons sharing an edge (doorway)", () => {
+  const left = [[0, 0], [100, 0], [100, 100], [0, 100]];
+  const right = [[100, 0], [200, 0], [200, 100], [100, 100]];
+  const wa = new WalkArea([left, right], { sampleStep: 20, portalEpsilon: 5 });
+  const path = wa.path([10, 50], [190, 50]);
+  assert.ok(path, "cross-polygon path found");
+  assert.deepEqual(path.at(-1), [190, 50]);
+  // every waypoint must be inside the walkable area
+  for (const p of path) assert.ok(wa.contains(p) || wa.clamp(p)[0] === p[0], `waypoint ${p} off-area`);
+});
+
+test("unreachable area returns null", () => {
+  const left = [[0, 0], [10, 0], [10, 10], [0, 10]];
+  const far = [[500, 500], [510, 500], [510, 510], [500, 510]];
+  const wa = new WalkArea([left, far], { sampleStep: 4, portalEpsilon: 5 });
+  assert.equal(wa.path([5, 5], [505, 505]), null);
+});
+
+test("click outside the area walks to the nearest edge", () => {
+  const wa = new WalkArea([square], { sampleStep: 20 });
+  const path = wa.path([50, 50], [150, 50]);
+  assert.ok(path);
+  assert.deepEqual(path.at(-1), wa.clamp([150, 50]));
+});