diff --git a/harness/adapters/melvor/README.md b/harness/adapters/melvor/README.md
new file mode 100644
index 0000000..04e9be3
--- /dev/null
+++ b/harness/adapters/melvor/README.md
@@ -0,0 +1,87 @@
+# harness/adapters/melvor/ — the Melvor Idle adapter
+
+A `Bridge<MelvorState>` over a running **Melvor Idle** instance (`TASKS.md` T2).
+It implements the substrate-agnostic contract from `../../bridge/` for Melvor:
+`observe()` snapshots the game; `act()` performs a skill action. Game specifics
+live here and never leak back into `bridge/`.
+
+```
+melvor/
+├── melvor-bridge.ts   MelvorBridge — observe()/act(); MelvorState + MelvorGameApi (the port)
+├── melvor-mod.ts      mod glue — binds the in-process `game` global to the port; createMelvorBridge()
+├── index.ts           public surface
+└── melvor-bridge.test.ts
+```
+
+The shape mirrors `../../bridge/synthetic-bridge.ts`: a per-affordance switch in
+`act()` and a snapshot in `observe()`. The difference is the world is **external**
+(a live game), so the bridge holds a reference to the game rather than owning
+in-memory state.
+
+## Perception & affordances
+
+`observe()` returns a `Perception<MelvorState>`:
+
+- `state.skills` — every skill with `id` / `name` / `level` / `xp`.
+- `state.activeActionId` — the one running action, or `null` when idle.
+- `affordances` — one `train:<skillId>` per skill (the target is in the id, so an
+  `Action` needs no params), plus `stop`. This is the menu the autotelic selector
+  chooses from.
+
+`act()` accepts `train:<skillId>` (→ start that skill) or `stop`; anything else is
+`rejected`. `observedAt` is the wall clock (Melvor is real-time, unlike the
+synthetic fixture's logical tick).
+
+## Act path: mod API (in-process), not CDP — decided by ADR-0006
+
+The act path was **already chosen at the architectural level by `adr-0006`**
+(polyglot: TS harness, Python cognition). That ADR picked the TypeScript harness
+*precisely so the adapter reads the `game` global in-process*, and explicitly
+rejected single-language Python because it "forces the Melvor adapter through
+Playwright / CDP `eval`, making `Perception` extraction … slower and more
+brittle than an in-process mod." So **no new ADR is filed** for T2 — this is the
+ADR's decision, applied:
+
+| | In-process mod (chosen) | CDP / headless-Chromium (rejected for perception) |
+|---|---|---|
+| Read | direct property access on `game` — no serialization | `Runtime.evaluate` round-trip returning a serialized snapshot |
+| Latency | none (same process) | one round-trip per read |
+| Fidelity | full object graph in scope | deep/cyclic game objects serialize poorly |
+
+CDP / OpenClaw stays relevant for the **operator gateway** (an orthogonal
+concern; `exploration/prior-art-l2-l3.md`), not for perception.
+
+The L2 **runtime** choice (ElizaOS-core / OpenClaw-gateway / Hermes-fallback lean)
+is *not* made here — T2 only needs the Bridge contract. It is committed via its
+own ADR when the loop needs it, **deferred to T5** (issue #25).
+
+## Shared-avatar concurrency — surfaced, not solved
+
+Melvor is **single-avatar**: one active action on one save. If the operator and
+the agent both drive the same instance, their `act()` calls race on that single
+slot (start-skill is last-writer-wins), and the agent's next `observe()` reports
+an `activeActionId` it did not set. This adapter does **not** arbitrate that —
+no lock, no turn-taking, no operator/agent identity on `Action`.
+
+Per `adr-0007`, the dyad's *operator-acts-in-world* half is staged to **Stardew
+(P1)**, whose native co-op gives separate avatars in one world and sidesteps the
+shared-avatar race entirely. Melvor (P0) proves only the agent-side loop.
+`SyntheticBridge.operatorAct()` is where dual-control is exercised
+deterministically in the meantime.
+
+## IP boundary — mod/bridge code only (AGENTS.md rule 4 · adr-0003)
+
+The Melvor game body is **never vendored**. The interfaces in `melvor-mod.ts`
+declare only the *shape* of the small in-process surface we bind to (clean-room);
+they are not copied from Melvor's source. Concrete field/method names are
+confirmed against the live `game` object at integration (the implementer runs a
+real Melvor + its mod toolchain — issue #25 preconditions). All game-coupling is
+isolated in `melvor-mod.ts`, so a name change touches one file.
+
+## Loading & testing
+
+- **In Melvor:** load the mod in-page and call `createMelvorBridge()`, which reads
+  `globalThis.game`. It throws off-page (e.g. plain Node) — the adapter only
+  works in-process.
+- **Tests:** a fake stands in for `game` (no Melvor needed). Run from `harness/`:
+  `npm run ci` (typecheck + tests + 100% coverage of the runtime surface).
diff --git a/harness/adapters/melvor/index.ts b/harness/adapters/melvor/index.ts
new file mode 100644
index 0000000..9d7b03f
--- /dev/null
+++ b/harness/adapters/melvor/index.ts
@@ -0,0 +1,5 @@
+// Public surface of the Melvor adapter.
+export { MelvorBridge } from "./melvor-bridge";
+export type { MelvorState, MelvorSkillView, MelvorGameApi } from "./melvor-bridge";
+export { bindMelvorGlobal, createMelvorBridge } from "./melvor-mod";
+export type { MelvorGlobal, MelvorSkillObject, MelvorActiveAction } from "./melvor-mod";
diff --git a/harness/adapters/melvor/melvor-bridge.test.ts b/harness/adapters/melvor/melvor-bridge.test.ts
new file mode 100644
index 0000000..a0f3702
--- /dev/null
+++ b/harness/adapters/melvor/melvor-bridge.test.ts
@@ -0,0 +1,162 @@
+// Tests for the Melvor adapter. Melvor itself is never loaded — a fake stands in
+// for the in-process `game` global (issue #25: "tests as feasible — mock the
+// game object"). Covers schema conformance, ≥1 real skill action through to a
+// changed Perception, every rejection path, the mod glue binder, and the
+// entrypoint's game-present / game-absent branches.
+
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+import Ajv2020 from "ajv/dist/2020.js";
+import { MelvorBridge } from "./melvor-bridge";
+import { bindMelvorGlobal, createMelvorBridge } from "./melvor-mod";
+import type { MelvorGlobal, MelvorSkillObject, MelvorActiveAction } from "./melvor-mod";
+
+const here = dirname(fileURLToPath(import.meta.url));
+const schema = (name: string): object =>
+  JSON.parse(readFileSync(join(here, "..", "..", "bridge", "schema", name), "utf8")) as object;
+
+const ajv = new Ajv2020({ strict: true, allErrors: true });
+const validatePerception = ajv.compile(schema("perception.schema.json"));
+const validateActionResult = ajv.compile(schema("action-result.schema.json"));
+
+// A minimal fake of the in-process `game` global: one wired skill (Woodcutting,
+// has a start hook) and one unwired skill (Fishing, no start hook). Starting
+// Woodcutting sets the active action; stopping it clears it.
+function makeFakeGame(): MelvorGlobal {
+  let active: MelvorActiveAction | null = null;
+  const woodcutting: MelvorSkillObject = {
+    id: "melvorD:Woodcutting",
+    name: "Woodcutting",
+    level: 1,
+    xp: 0,
+    start: () => {
+      active = { id: "melvorD:Woodcutting", stop: () => (active = null) };
+      return true;
+    },
+  };
+  const fishing: MelvorSkillObject = {
+    id: "melvorD:Fishing",
+    name: "Fishing",
+    level: 1,
+    xp: 0,
+    // intentionally no start hook — an "unwired" skill
+  };
+  const skills = [woodcutting, fishing];
+  return {
+    skills: {
+      get allObjects() {
+        return skills;
+      },
+    },
+    get activeAction() {
+      return active;
+    },
+  };
+}
+
+test("observe() returns a populated Perception that conforms to the canonical schema", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+  const p = await bridge.observe();
+
+  assert.ok(validatePerception(p), ajv.errorsText(validatePerception.errors));
+  assert.equal(p.substrate, "melvor");
+  assert.ok(Number.isInteger(p.observedAt) && p.observedAt >= 0);
+  assert.equal(p.state.activeActionId, null); // idle to start
+  assert.deepEqual(
+    p.state.skills.map((s) => s.id),
+    ["melvorD:Woodcutting", "melvorD:Fishing"],
+  );
+  // one "train:" affordance per skill, plus the stop affordance
+  assert.equal(p.affordances.length, 3);
+  assert.deepEqual(
+    p.affordances.map((a) => a.id),
+    ["train:melvorD:Woodcutting", "train:melvorD:Fishing", "stop"],
+  );
+});
+
+test("act() performs a skill action and the next observe() reflects it", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+
+  const r = await bridge.act({
+    affordance: "train:melvorD:Woodcutting",
+    reason: "what does it feel like to gather wood rather than grind?",
+  });
+  assert.ok(validateActionResult(r), ajv.errorsText(validateActionResult.errors));
+  assert.equal(r.status, "ok");
+  assert.equal((await bridge.observe()).state.activeActionId, "melvorD:Woodcutting");
+
+  const stop = await bridge.act({ affordance: "stop" });
+  assert.equal(stop.status, "ok");
+  assert.equal((await bridge.observe()).state.activeActionId, null);
+});
+
+test("stop on an idle world is an accepted no-op", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+  const r = await bridge.act({ affordance: "stop" });
+  assert.equal(r.status, "ok");
+  assert.equal((await bridge.observe()).state.activeActionId, null);
+});
+
+test("training an unwired skill is rejected, leaving the world idle", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+  const r = await bridge.act({ affordance: "train:melvorD:Fishing" });
+  assert.equal(r.status, "rejected");
+  assert.match(r.detail ?? "", /cannot start skill: melvorD:Fishing/);
+  assert.equal((await bridge.observe()).state.activeActionId, null);
+});
+
+test("training an unknown skill id is rejected", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+  const r = await bridge.act({ affordance: "train:melvorD:Nope" });
+  assert.equal(r.status, "rejected");
+  assert.match(r.detail ?? "", /cannot start skill: melvorD:Nope/);
+});
+
+test("an affordance the adapter does not recognize is rejected", async () => {
+  const bridge = new MelvorBridge(bindMelvorGlobal(makeFakeGame()));
+  const r = await bridge.act({ affordance: "teleport" });
+  assert.equal(r.status, "rejected");
+  assert.match(r.detail ?? "", /unknown affordance: teleport/);
+});
+
+test("bindMelvorGlobal reports the active action id when one is running", async () => {
+  const game = makeFakeGame();
+  const api = bindMelvorGlobal(game);
+  assert.equal(api.activeActionId(), null);
+  api.startSkill("melvorD:Woodcutting");
+  assert.equal(api.activeActionId(), "melvorD:Woodcutting");
+  api.stopActive();
+  assert.equal(api.activeActionId(), null);
+});
+
+test("close() resolves", async () => {
+  await assert.doesNotReject(() => new MelvorBridge(bindMelvorGlobal(makeFakeGame())).close());
+});
+
+test("createMelvorBridge builds a bridge from the page's game global", async () => {
+  const slot = globalThis as { game?: MelvorGlobal };
+  const prior = slot.game;
+  try {
+    slot.game = makeFakeGame();
+    const bridge = createMelvorBridge();
+    assert.ok(bridge instanceof MelvorBridge);
+    assert.equal((await bridge.observe()).substrate, "melvor");
+  } finally {
+    if (prior === undefined) delete slot.game;
+    else slot.game = prior;
+  }
+});
+
+test("createMelvorBridge throws off-page where no game global exists", () => {
+  const slot = globalThis as { game?: MelvorGlobal };
+  const prior = slot.game;
+  try {
+    delete slot.game;
+    assert.throws(() => createMelvorBridge(), /game` global not found/);
+  } finally {
+    if (prior !== undefined) slot.game = prior;
+  }
+});
diff --git a/harness/adapters/melvor/melvor-bridge.ts b/harness/adapters/melvor/melvor-bridge.ts
new file mode 100644
index 0000000..6e3ec67
--- /dev/null
+++ b/harness/adapters/melvor/melvor-bridge.ts
@@ -0,0 +1,130 @@
+// MelvorBridge — a Bridge<MelvorState> over a running Melvor Idle instance.
+// Mirrors the structure of bridge/synthetic-bridge.ts (the worked reference):
+// observe() snapshots the world, act() applies one affordance via a private
+// switch. The difference is the world is *external* — a live game — so instead
+// of owning in-memory state, the bridge holds a reference to the game and reads
+// through it on every observe().
+//
+// ── Act path: mod API (in-process), NOT CDP / headless-Chromium ───────────────
+// This is already decided at the architectural level by ADR-0006 (polyglot:
+// TypeScript harness, Python cognition), which chose the TS harness *precisely
+// so the adapter can read the `game` global in-process* and rejected the
+// single-language-Python alternative because it "forces the Melvor adapter
+// through Playwright / CDP `eval`, making `Perception` extraction from the
+// `game` global slower and more brittle than an in-process mod." So no new ADR
+// is filed here — this comment records the act-path choice the ADR already made:
+//
+//   - In-process mod: direct property reads off `game` (no serialization, no
+//     round-trip), synchronous control calls, and the richest perception — the
+//     whole object graph is in scope. This is the path.
+//   - CDP / headless-Chromium: every read is a `Runtime.evaluate` round-trip
+//     returning a serialized snapshot; deep/cyclic game objects serialize
+//     poorly and each observe() pays latency. Rejected for perception. (CDP/
+//     OpenClaw remains a candidate for the *operator gateway*, an orthogonal
+//     concern — see exploration/prior-art-l2-l3.md.)
+//
+// ── Runtime (ElizaOS / OpenClaw / Hermes) is NOT chosen here ──────────────────
+// T2 is just an adapter implementing the Bridge contract; it does not need the
+// L2 runtime selected. The lean (ElizaOS-core + OpenClaw-gateway + Hermes-
+// fallback, exploration/prior-art-l2-l3.md) is committed via its own ADR when
+// the loop needs it — deferred to T5 per issue #25.
+//
+// ── Shared-avatar concurrency (SURFACED, not solved) ──────────────────────────
+// Melvor is single-avatar: there is exactly one active action on one save. If
+// the operator and the agent both drive the same instance, their act() calls
+// race on that single slot — start-skill is last-writer-wins, and the agent's
+// next observe() will report an activeActionId it did not set (a change it
+// didn't cause). This bridge does NOT arbitrate that: there is no lock, no
+// turn-taking, no operator/agent identity on Action. Per ADR-0007 the dyad's
+// operator-acts-in-world half is staged to Stardew (P1), whose native co-op
+// gives separate avatars in one world and sidesteps this shared-avatar race
+// entirely. On Melvor (P0) we only prove the agent-side loop. SyntheticBridge
+// .operatorAct() is where dual-control is exercised deterministically meanwhile.
+//
+// ── IP boundary (AGENTS.md rule 4 · ADR-0003) ─────────────────────────────────
+// Mod/bridge code only — the Melvor game body is never vendored. The types in
+// melvor-mod.ts declare only the *shape* of the small in-process surface we
+// bind to (clean-room), not Melvor's source.
+
+import type { Bridge } from "../../bridge/bridge";
+import type { Perception, ActionSpec } from "../../bridge/perception";
+import type { Action, ActionResult } from "../../bridge/action";
+
+/** One skill as seen by the agent. JSON-serializable, like any substrate state. */
+export interface MelvorSkillView {
+  /** Namespaced skill id, e.g. "melvorD:Woodcutting". */
+  id: string;
+  /** Display name, e.g. "Woodcutting". */
+  name: string;
+  level: number;
+  xp: number;
+}
+
+/** Melvor's world snapshot — the typed `state` inside a Perception. */
+export interface MelvorState {
+  /** Id of the currently active action, or null if the avatar is idle. */
+  activeActionId: string | null;
+  /** Every skill, with its current level and xp. */
+  skills: MelvorSkillView[];
+}
+
+/**
+ * The minimal control+read surface the bridge needs from Melvor, implemented by
+ * the mod over the in-process `game` global (see `bindMelvorGlobal` in
+ * melvor-mod.ts). Stated as a port so the bridge logic is unit-testable with a
+ * fake, and the brittle game-coupling is confined to one documented place.
+ */
+export interface MelvorGameApi {
+  /** Snapshot every skill. */
+  listSkills(): MelvorSkillView[];
+  /** Id of the active action, or null when idle. */
+  activeActionId(): string | null;
+  /** Begin training a skill; false if the game refused (unknown / not wired / reqs unmet). */
+  startSkill(skillId: string): boolean;
+  /** Stop whatever is active; a no-op when already idle. */
+  stopActive(): void;
+}
+
+const TRAIN_PREFIX = "train:";
+
+export class MelvorBridge implements Bridge<MelvorState> {
+  constructor(private readonly game: MelvorGameApi) {}
+
+  async observe(): Promise<Perception<MelvorState>> {
+    const skills = this.game.listSkills();
+    const affordances: ActionSpec[] = [
+      // One "train this skill" affordance per skill — the menu the autotelic
+      // selector chooses from. The target skill is encoded in the id so an
+      // Action needs no params (mirrors the bare-id affordances in synthetic).
+      ...skills.map((s) => ({ id: `${TRAIN_PREFIX}${s.id}`, label: `Train ${s.name}` })),
+      { id: "stop", label: "Stop the active action" },
+    ];
+    return {
+      substrate: "melvor",
+      // Melvor is real-time (unlike the synthetic fixture's logical tick), so
+      // observedAt is the wall clock — an epoch-ms integer per the schema.
+      observedAt: Date.now(),
+      state: { activeActionId: this.game.activeActionId(), skills },
+      affordances,
+    };
+  }
+
+  async act(action: Action): Promise<ActionResult> {
+    const { affordance } = action;
+    if (affordance === "stop") {
+      this.game.stopActive();
+      return { status: "ok" };
+    }
+    if (affordance.startsWith(TRAIN_PREFIX)) {
+      const skillId = affordance.slice(TRAIN_PREFIX.length);
+      return this.game.startSkill(skillId)
+        ? { status: "ok" }
+        : { status: "rejected", detail: `cannot start skill: ${skillId}` };
+    }
+    return { status: "rejected", detail: `unknown affordance: ${affordance}` };
+  }
+
+  async close(): Promise<void> {
+    // In-process: nothing to release (the mod shares the page's lifetime).
+  }
+}
diff --git a/harness/adapters/melvor/melvor-mod.ts b/harness/adapters/melvor/melvor-mod.ts
new file mode 100644
index 0000000..87aedd4
--- /dev/null
+++ b/harness/adapters/melvor/melvor-mod.ts
@@ -0,0 +1,83 @@
+// melvor-mod.ts — the mod glue: binds Melvor's in-process `game` global to the
+// MelvorGameApi port that MelvorBridge consumes. This is the one place that
+// names concrete game members, so all game-coupling (and its integration risk)
+// lives here, isolated from the bridge logic.
+//
+// CLEAN-ROOM (AGENTS.md rule 4 · ADR-0003): the interfaces below declare only
+// the *shape* of the small surface we touch — they are not copied from Melvor's
+// source, and the game body is never vendored. Field/method names are confirmed
+// against the live `game` object at integration time (the implementer runs a
+// real Melvor + its mod toolchain; see issue #25 preconditions). Keeping the
+// dependency this thin means a name change touches only this file.
+
+import { MelvorBridge } from "./melvor-bridge";
+import type { MelvorGameApi, MelvorSkillView } from "./melvor-bridge";
+
+/** A skill object as exposed on the in-process `game`. Reads only, except `start`. */
+export interface MelvorSkillObject {
+  /** Namespaced id, e.g. "melvorD:Woodcutting". */
+  readonly id: string;
+  readonly name: string;
+  readonly level: number;
+  readonly xp: number;
+  /**
+   * The mod's start hook for this skill. Melvor has no single uniform "start a
+   * skill" entrypoint — each skill begins differently (Woodcutting selects a
+   * tree, Mining a rock, Fishing an area, …). The mod wires this per skill at
+   * integration; an unwired skill leaves `start` absent and startSkill() reports
+   * `rejected` rather than guessing. Returns false if the game itself refused
+   * (e.g. level/requirement unmet).
+   */
+  start?: () => boolean;
+}
+
+/** The active action, when one is running. */
+export interface MelvorActiveAction {
+  readonly id: string;
+  /** Halt this action. Present on Melvor's skill/action objects. */
+  stop(): void;
+}
+
+/** The subset of the Melvor `game` global this adapter binds to. */
+export interface MelvorGlobal {
+  readonly skills: { readonly allObjects: readonly MelvorSkillObject[] };
+  /** Currently active action, or null when the avatar is idle. */
+  readonly activeAction: MelvorActiveAction | null;
+}
+
+/** Adapt the real `game` global to the port the bridge consumes. */
+export function bindMelvorGlobal(game: MelvorGlobal): MelvorGameApi {
+  const view = (s: MelvorSkillObject): MelvorSkillView => ({
+    id: s.id,
+    name: s.name,
+    level: s.level,
+    xp: s.xp,
+  });
+  return {
+    listSkills: () => game.skills.allObjects.map(view),
+    activeActionId: () => game.activeAction?.id ?? null,
+    startSkill: (skillId) => {
+      const skill = game.skills.allObjects.find((s) => s.id === skillId);
+      if (!skill || !skill.start) return false;
+      return skill.start();
+    },
+    stopActive: () => {
+      game.activeAction?.stop();
+    },
+  };
+}
+
+/**
+ * Mod entrypoint: build a MelvorBridge from the page's `game` global. Call this
+ * from the loaded mod, where `game` is in scope. Throws off-page (e.g. in a
+ * plain Node process) where no game exists — the adapter only works in-process.
+ */
+export function createMelvorBridge(): MelvorBridge {
+  const g = (globalThis as { game?: MelvorGlobal }).game;
+  if (!g) {
+    throw new Error(
+      "Melvor `game` global not found — load this adapter as a Melvor mod, in-page.",
+    );
+  }
+  return new MelvorBridge(bindMelvorGlobal(g));
+}
diff --git a/harness/package.json b/harness/package.json
index f61b6b8..c0509a6 100644
--- a/harness/package.json
+++ b/harness/package.json
@@ -7,8 +7,8 @@
   "license": "AGPL-3.0-only",
   "scripts": {
     "typecheck": "tsc --noEmit",
-    "test": "tsx --test bridge/*.test.ts",
-    "test:coverage": "node --import tsx --test --experimental-test-coverage --test-coverage-exclude='**/*.test.ts' --test-coverage-lines=100 --test-coverage-functions=100 --test-coverage-branches=100 bridge/*.test.ts",
+    "test": "tsx --test bridge/*.test.ts adapters/*/*.test.ts",
+    "test:coverage": "node --import tsx --test --experimental-test-coverage --test-coverage-exclude='**/*.test.ts' --test-coverage-lines=100 --test-coverage-functions=100 --test-coverage-branches=100 bridge/*.test.ts adapters/*/*.test.ts",
     "ci": "npm run typecheck && npm run test:coverage"
   },
   "devDependencies": {
diff --git a/harness/tsconfig.json b/harness/tsconfig.json
index 98e0336..e145e0d 100644
--- a/harness/tsconfig.json
+++ b/harness/tsconfig.json
@@ -13,5 +13,5 @@
     "skipLibCheck": true,
     "noEmit": true
   },
-  "include": ["bridge/**/*.ts"]
+  "include": ["bridge/**/*.ts", "adapters/**/*.ts"]
 }