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/render.test.js

@@ -0,0 +1,123 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { AssetManifest } from "../src/render/assets.js";
+import { HeadlessAudio } from "../src/render/audio.js";
+import { RoomRenderer } from "../src/render/canvas.js";
+import { HudModel } from "../src/render/hud.js";
+import { Engine } from "../src/core/engine.js";
+
+const example = JSON.parse(readFileSync(new URL("../example/game.json", import.meta.url), "utf8"));
+
+// ---- assets ---------------------------------------------------------------
+test("asset manifest resolves and degrades gracefully", () => {
+  const am = new AssetManifest(example.assets);
+  assert.equal(am.get("bg_jetty").file, "assets/img/jetty.png");
+  const missing = am.get("nope");
+  assert.equal(missing.missing, true);
+  assert.equal(am.get("nope").missing, true);   // second call: no crash
+});
+
+test("animation frame cycling", () => {
+  const am = new AssetManifest([{ id: "p", file: "p.png", frames: { walk: [0, 1, 1, 0] }, anim: { walk: 100 } }]);
+  const a = am.get("p");
+  assert.equal(am.frameFor(a, "walk", 0), 0);
+  assert.equal(am.frameFor(a, "walk", 100), 1);
+  assert.equal(am.frameFor(a, "walk", 300), 0);
+  assert.equal(am.frameFor(a, "unknownAnim", 0), 0);   // falls back
+});
+
+// ---- audio ----------------------------------------------------------------
+test("headless audio records calls and preserves loop points", () => {
+  const au = new HeadlessAudio();
+  au.playMusic({ id: "calypso", file: "c.ogg", loopStartMs: 8460, loopEndMs: 76920 });
+  au.playSfx({ id: "click", file: "k.ogg" });
+  au.setVolume(2);      // clamped
+  assert.deepEqual(au.calls[0], { op: "playMusic", id: "calypso", file: "c.ogg",
+                                  loopStartMs: 8460, loopEndMs: 76920 });
+  assert.equal(au.calls[1].op, "playSfx");
+  assert.equal(au.volume, 1);
+  au.stopMusic();
+  assert.equal(au.current, null);
+});
+
+// ---- canvas renderer (fake recording context) ------------------------------
+function fakeCtx() {
+  const ops = [];
+  const noop = (name) => (...args) => ops.push({ op: name, args });
+  return { ops, drawImage: noop("drawImage"), fillRect: noop("fillRect"),
+           fillText: noop("fillText"), beginPath: noop("beginPath"),
+           lineTo: noop("lineTo"), moveTo: noop("moveTo"), closePath: noop("closePath"),
+           fill: noop("fill"), save: noop("save"), restore: noop("restore") };
+}
+
+test("renderer draws bg, placeholders, and exit labels", () => {
+  const e = new Engine(structuredClone(example), { clock: () => 0 });
+  e.newGame();
+  const am = new AssetManifest(example.assets);
+  const rr = new RoomRenderer(e.compiled, am, new Map());   // no images loaded
+  const ctx = fakeCtx();
+  rr.draw(e, ctx, { timeMs: 0 });
+  assert.ok(ctx.ops.some((o) => o.op === "fillRect"));          // bg placeholder
+  assert.ok(ctx.ops.some((o) => o.op === "fillText" && o.args[0] === "Tavern"));
+  // player + objects drawn as labelled placeholders
+  const labels = ctx.ops.filter((o) => o.op === "fillText").map((o) => o.args[0]);
+  assert.ok(labels.includes("player"));
+  assert.ok(labels.includes("post"));
+  assert.ok(labels.includes("mug"));
+});
+
+test("renderer uses loaded images when present", () => {
+  const e = new Engine(structuredClone(example), { clock: () => 0 });
+  e.newGame();
+  const am = new AssetManifest(example.assets);
+  const images = new Map([["bg_jetty", { width: 640, height: 480 }]]);
+  const rr = new RoomRenderer(e.compiled, am, images);
+  const ctx = fakeCtx();
+  rr.draw(e, ctx, { timeMs: 0 });
+  assert.ok(ctx.ops.some((o) => o.op === "drawImage"));
+});
+
+test("object placeholder boxes match hotspot rects (see-what-you-click)", () => {
+  const e = new Engine(structuredClone(example), { clock: () => 0 });
+  e.newGame();
+  const rr = new RoomRenderer(e.compiled, new AssetManifest(example.assets), new Map());
+  const ctx = fakeCtx();
+  rr.draw(e, ctx, { timeMs: 0 });
+  const rects = ctx.ops.filter((o) => o.op === "fillRect").map((o) => o.args);
+  // post hotspot {480,300,40,90} and mug {200,360,40,30} drawn exactly
+  assert.ok(rects.some((r) => r[0] === 480 && r[1] === 300 && r[2] === 40 && r[3] === 90),
+            `post box not at hotspot: ${JSON.stringify(rects)}`);
+  assert.ok(rects.some((r) => r[0] === 200 && r[1] === 360 && r[2] === 40 && r[3] === 30),
+            `mug box not at hotspot: ${JSON.stringify(rects)}`);
+});
+
+test("walkable debug draws polygons", () => {
+  const e = new Engine(structuredClone(example), { clock: () => 0 });
+  e.newGame();
+  const rr = new RoomRenderer(e.compiled, new AssetManifest(example.assets), new Map());
+  const ctx = fakeCtx();
+  rr.draw(e, ctx, { timeMs: 0, debugWalkable: true });
+  assert.ok(ctx.ops.some((o) => o.op === "closePath"));
+});
+
+// ---- HUD model --------------------------------------------------------------
+test("hud exposes verbs, inventory, dialogue choices, save gate", () => {
+  const e = new Engine(structuredClone(example), { clock: () => 0 });
+  e.newGame();
+  const hud = new HudModel(e);
+  assert.equal(hud.verbs().length, 5);
+  e.selectVerb("look");
+  assert.equal(hud.verbs().find((v) => v.id === "look").selected, true);
+  assert.deepEqual(hud.inventory(), []);
+  e.selectVerb("use");
+  e.click({ kind: "object", id: "mug", tags: ["container"] });
+  assert.deepEqual(hud.inventory(), [{ id: "mug", name: "a suspicious mug" }]);
+  assert.equal(hud.canSave(), true);
+  e.goTo("tavern");
+  e.selectVerb("talk");
+  e.click({ kind: "character", id: "barkeep", tags: ["talker"] });
+  assert.equal(hud.inDialogue(), true);
+  assert.equal(hud.dialogueChoices().length, 2);
+  assert.equal(hud.canSave(), false, "no saving mid-dialogue");
+});