feat(v0.4.0): finish vNext plan — anti-loop, skill-graph, worldDelta diff, flee→motion

Completes the remaining v0.4.0 plan items and one fix motivated by a live
in-game observation (flee hanging 30s against a persistent zombie).

- flee → MotionService.gotoSafe: structured {stuck|timeout|nopath} in ~4s with
  a blind-retreat fallback, instead of the observed 30s pathfinder hang + 3
  watchdog replans. Movements setup guarded so it is unit-testable.
- QW5 anti-loop (runtime/anti-loop.js): same skill failing >=3x in 5min →
  30min blacklist (reflex shouldSkip) + one-shot improvement_request
  (bot.js drainFired -> writeProposal).
- 4.1 closed-loop worldDelta: runSkill snapshots inventory before execute and
  attaches the real delta (_invObserved) to every successful result; opt-in
  skill.expectGain asserts the claimed gain or returns world_unchanged.
- 3.6 skill-graph (Plan4MC): declarative requires/produces for ~20 skills;
  prerequisitesMet/canRun/runnableFrontier; GoalManager annotates suggestions
  with blockedBy when prereqs are unmet.

+22 tests (472 total green). Live smoke confirmed dig-in works and no new
errors; flee loop is what this commit's flee migration addresses.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

runtime/anti-loop.test.js

@@ -0,0 +1,58 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+import { createAntiLoop } from "./anti-loop.js";
+
+test("fires after N failures in the window and blacklists the skill", () => {
+	const al = createAntiLoop({ windowMs: 60_000, threshold: 3, blacklistMs: 30_000 });
+	assert.equal(al.record({ skillId: "survive.flee", ok: false, now: 1000 }).fired, false);
+	assert.equal(al.record({ skillId: "survive.flee", ok: false, now: 2000 }).fired, false);
+	const third = al.record({ skillId: "survive.flee", ok: false, now: 3000 });
+	assert.equal(third.fired, true);
+	assert.equal(third.count, 3);
+	assert.equal(al.shouldSkip("survive.flee", null, 4000), true);
+	assert.equal(al.shouldSkip("survive.flee", null, 40_000), false); // blacklist expired
+});
+
+test("a success resets the fail streak", () => {
+	const al = createAntiLoop({ threshold: 3 });
+	al.record({ skillId: "gather.logs", ok: false, now: 1 });
+	al.record({ skillId: "gather.logs", ok: false, now: 2 });
+	al.record({ skillId: "gather.logs", ok: true, now: 3 });
+	const r = al.record({ skillId: "gather.logs", ok: false, now: 4 });
+	assert.equal(r.fired, false);
+});
+
+test("failures outside the window do not accumulate", () => {
+	const al = createAntiLoop({ windowMs: 1000, threshold: 3 });
+	al.record({ skillId: "s", ok: false, now: 0 });
+	al.record({ skillId: "s", ok: false, now: 500 });
+	const r = al.record({ skillId: "s", ok: false, now: 5000 }); // first two pruned
+	assert.equal(r.fired, false);
+});
+
+test("targetKey separates loops on different targets", () => {
+	const al = createAntiLoop({ threshold: 2 });
+	al.record({ skillId: "mine", ok: false, targetKey: "A", now: 1 });
+	const a2 = al.record({ skillId: "mine", ok: false, targetKey: "A", now: 2 });
+	assert.equal(a2.fired, true);
+	const b1 = al.record({ skillId: "mine", ok: false, targetKey: "B", now: 3 });
+	assert.equal(b1.fired, false); // different target, own streak
+});
+
+test("drainFired returns and clears the queue", () => {
+	const al = createAntiLoop({ threshold: 2 });
+	al.record({ skillId: "x", ok: false, now: 1 });
+	al.record({ skillId: "x", ok: false, now: 2 });
+	assert.equal(al.drainFired().length, 1);
+	assert.equal(al.drainFired().length, 0);
+});
+
+test("refire cooldown prevents immediate re-fire", () => {
+	const al = createAntiLoop({ threshold: 2, blacklistMs: 1000, refireCooldownMs: 100_000 });
+	al.record({ skillId: "x", ok: false, now: 1 });
+	assert.equal(al.record({ skillId: "x", ok: false, now: 2 }).fired, true);
+	// after blacklist expires, two more fails — within refire cooldown → no fire
+	al.record({ skillId: "x", ok: false, now: 2000 });
+	assert.equal(al.record({ skillId: "x", ok: false, now: 2100 }).fired, false);
+});