diff --git a/runtime/actions.js b/runtime/actions.js
index 0050e23..5cbe9b4 100644
--- a/runtime/actions.js
+++ b/runtime/actions.js
@@ -372,6 +372,11 @@ export async function chopNearestTree(bot) {
 	});
 	if (!log) return { ok: false, detail: `no reachable log within ${SEARCH_RADIUS} blocks` };
 
+	// 2026-05-26: ground-truth verification + lookAt+force. On
+	// play.xmatic.team (1.21 via ViaBackwards) bot.dig/collect can return
+	// success even when the block survives — the server silently drops our
+	// serverbound packet (project_mineflayer_via_protocol_pin). We refuse
+	// to call it ok unless the block is actually gone from the world.
 	ensureCollectBlock(bot);
 	setMovementsForGather(bot);
 	const axe = await equipBestAxe(bot);
@@ -379,14 +384,29 @@ export async function chopNearestTree(bot) {
 		"action",
 		`chop: ${log.name} at ${log.position.x},${log.position.y},${log.position.z} (tool=${axe ?? "fists"})`,
 	);
+	const targetPos = log.position.clone();
+	const key = `${targetPos.x},${targetPos.y},${targetPos.z}`;
 	try {
+		try {
+			await withTimeout(bot.lookAt(targetPos.offset(0.5, 0.5, 0.5), true), 2_000, "lookAt(log)");
+		} catch {}
 		await withTimeout(bot.collectBlock.collect(log), 60_000, "collectLog");
-		return { ok: true, detail: { logType: log.name, at: log.position } };
+		const after = bot.blockAt(targetPos);
+		if (after && LOG_NAMES.includes(after.name)) {
+			warn("action", `chop reported ok but log still at ${key} — silent dig failure`);
+			blacklist.set(key, Date.now() + BLACKLIST_TTL_MS);
+			return {
+				ok: false,
+				code: "silent_dig_failure",
+				detail: "block still exists after collect — server dropped dig packet?",
+				blacklisted: targetPos,
+			};
+		}
+		return { ok: true, detail: { logType: log.name, at: targetPos } };
 	} catch (e) {
 		warn("action", `chop failed: ${e.message}`);
-		const key = `${log.position.x},${log.position.y},${log.position.z}`;
 		blacklist.set(key, Date.now() + BLACKLIST_TTL_MS);
-		return { ok: false, detail: e.message, blacklisted: log.position };
+		return { ok: false, detail: e.message, blacklisted: targetPos };
 	}
 }
 
diff --git a/runtime/bot.js b/runtime/bot.js
index ab0cd51..8f67912 100644
--- a/runtime/bot.js
+++ b/runtime/bot.js
@@ -42,6 +42,7 @@ import { createNoProgressDetector } from "./no-progress.js";
 import { maybeStartViewer } from "./viewer.js";
 import { nextMilestone as nextCurriculumMilestone } from "./curriculum.js";
 import { listLocations } from "./locations.js";
+import { runSkill } from "./skills/index.js";
 import { classifyIntent, INTENTS } from "./social/intent.js";
 import { generateReply } from "./social/reply.js";
 import { createChatMemory } from "./social/memory.js";
@@ -803,6 +804,46 @@ function handleCommand(msg, send) {
 			}
 			break;
 		}
+		case COMMAND_TYPES.RUN_SKILL: {
+			const skillId = msg.payload?.skillId;
+			const args = msg.payload?.args ?? {};
+			if (!skillId) {
+				send(EVENT_TYPES.ERROR, { source: "run-skill", text: "missing skillId" });
+				return;
+			}
+			info("ipc", `run-skill: queued ${skillId} args=${JSON.stringify(args)} (will wait for current action)`);
+			// Pause the reflex loop while we wait so it doesn't immediately
+			// schedule another action and starve our request.
+			const wasPaused = reflexPaused;
+			reflexPaused = true;
+			const deadline = Date.now() + 120_000;
+			const tryDispatch = () => {
+				if (!reflexCtx.busy) {
+					info("ipc", `run-skill: dispatching ${skillId}`);
+					dispatchAction(() => runSkill(skillId, reflexCtx, args), `ipc:${skillId}`, {
+						onComplete: (res) => {
+							reflexPaused = wasPaused;
+							send(EVENT_TYPES.LOG, {
+								ts: new Date().toISOString(),
+								level: "info",
+								source: "run-skill",
+								text: `${skillId} → ${res.code ?? (res.ok ? "ok" : "fail")}`,
+								details: res,
+							});
+						},
+					});
+					return;
+				}
+				if (Date.now() > deadline) {
+					reflexPaused = wasPaused;
+					send(EVENT_TYPES.ERROR, { source: "run-skill", text: `still busy after 2 min with ${reflexCtx.currentActionLabel}` });
+					return;
+				}
+				setTimeout(tryDispatch, 500);
+			};
+			tryDispatch();
+			break;
+		}
 		default:
 			warn("ipc", `unknown command type: ${msg.type}`);
 	}
diff --git a/runtime/compat.test.js b/runtime/compat.test.js
index 7b41699..fc5e32d 100644
--- a/runtime/compat.test.js
+++ b/runtime/compat.test.js
@@ -13,16 +13,20 @@ import { isManMadeBlockName, classifyArea, shouldAvoid } from "./claim-avoidance
 // We can't import owned-blocks.js until config-driven stateDir exists,
 // so it's tested via an isolated import in a temp dir below.
 
-test("movement profile descriptor: gather has canDig=true, canPlace=false", () => {
+// 2026-05-26: canDig is FALSE on every profile because bot.dig silently
+// fails on the live server (mineflayer #3888 / protocol 775). Once the
+// 1.21.4 pin restores real digging, gather/travel/flee profiles can flip
+// canDig back to true.
+test("movement profile descriptor: gather has canDig=false (silent-dig safeguard)", () => {
 	const d = describeProfile(PROFILES.GATHER);
-	assert.equal(d.canDig, true);
+	assert.equal(d.canDig, false);
 	assert.equal(d.canPlace, false);
 	assert.equal(d.allow1by1towers, false);
 });
 
-test("movement profile descriptor: flee allows higher drop, still canDig=true", () => {
+test("movement profile descriptor: flee allows higher drop, canDig=false", () => {
 	const d = describeProfile(PROFILES.FLEE);
-	assert.equal(d.canDig, true);
+	assert.equal(d.canDig, false);
 	assert.equal(d.maxDropDown, 8);
 });
 
diff --git a/runtime/ipc-protocol.js b/runtime/ipc-protocol.js
index 04c40a5..6f5c48d 100644
--- a/runtime/ipc-protocol.js
+++ b/runtime/ipc-protocol.js
@@ -27,6 +27,7 @@ export const COMMAND_TYPES = Object.freeze({
 	SNAPSHOT: "cmd:snapshot", // request immediate STATUS event
 	PROPOSAL_LATEST: "cmd:proposal-latest", // request latest pending proposal
 	PROPOSAL_APPROVE: "cmd:proposal-approve", // { filename } move to approved/
+	RUN_SKILL: "cmd:run-skill", // { skillId, args? } dispatch a skill once (operator ground-truth probes)
 });
 
 export function encodeFrame(obj) {
diff --git a/runtime/movement-profiles.js b/runtime/movement-profiles.js
index f405554..13e7795 100644
--- a/runtime/movement-profiles.js
+++ b/runtime/movement-profiles.js
@@ -19,16 +19,19 @@ export const PROFILES = Object.freeze({
 });
 
 // Pure descriptors — safe to import without a live bot.
+//
+// canDig is FALSE everywhere by default (2026-05-26). On the live server
+// (play.xmatic.team 26.1.2+ViaBackwards 5.9.1) bot.dig silently fails —
+// the packet ID table for protocol 775 is wrong in minecraft-data
+// (mineflayer#3888) — so pathfinder would schedule paths through
+// must-dig blocks the bot can't actually break, and we'd loop. Once
+// 1.21.4 pin + lookAt+wait fix is verified live, we can re-enable
+// canDig for gather/travel profiles.
 export const PROFILE_DEFAULTS = Object.freeze({
-	[PROFILES.GATHER]: { canDig: true, canPlace: false, allow1by1towers: false },
-	[PROFILES.TRAVEL]: { canDig: true, canPlace: false, allow1by1towers: false },
-	// canDig:true on flee is deliberate — observed live: flee with canDig=false
-	// in dense canopy leaves the bot perched in leaves indefinitely.
-	[PROFILES.FLEE]: { canDig: true, canPlace: false, allow1by1towers: false, maxDropDown: 8 },
-	// Build: don't accidentally mine the structure we're placing; allow
-	// 1x1 step-ups so shelter blueprints can layer.
+	[PROFILES.GATHER]: { canDig: false, canPlace: false, allow1by1towers: false },
+	[PROFILES.TRAVEL]: { canDig: false, canPlace: false, allow1by1towers: false },
+	[PROFILES.FLEE]: { canDig: false, canPlace: false, allow1by1towers: false, maxDropDown: 8 },
 	[PROFILES.BUILD]: { canDig: false, canPlace: true, allow1by1towers: true },
-	// Return: don't carve tunnels home or place stepping blocks; just walk.
 	[PROFILES.RETURN_TO_BASE]: { canDig: false, canPlace: false, allow1by1towers: false },
 });
 
diff --git a/runtime/skills/chop-logs.js b/runtime/skills/chop-logs.js
index c51f556..c29dcad 100644
--- a/runtime/skills/chop-logs.js
+++ b/runtime/skills/chop-logs.js
@@ -32,11 +32,15 @@ export const skill = Object.freeze({
 			};
 		}
 		const msg = String(res.detail ?? "");
-		const code = (msg.includes("no reachable log") || msg.includes("no log within"))
-			? "no_target"
-			: msg.includes("timed out")
-				? "timeout"
-				: "failed";
+		// res.code can come straight from actions.js (silent_dig_failure),
+		// otherwise we classify from the detail string.
+		const code = res.code
+			? res.code
+			: (msg.includes("no reachable log") || msg.includes("no log within"))
+				? "no_target"
+				: msg.includes("timed out")
+					? "timeout"
+					: "failed";
 		return { ok: false, code, detail: res.detail, worldDelta: null };
 	},
 	validate(ctx, result) {
diff --git a/runtime/skills/diagnose-physics.js b/runtime/skills/diagnose-physics.js
new file mode 100644
index 0000000..0dffb83
--- /dev/null
+++ b/runtime/skills/diagnose-physics.js
@@ -0,0 +1,119 @@
+// diag.physics — one-shot ground truth probe. Tests whether
+// setControlState("forward"), setControlState("jump"), and bot.dig
+// actually do anything on this server. Writes results to the diary so
+// the operator can inspect later. NOT for production loops — it has
+// side effects (1-2 blocks moved if forward works) and we don't want
+// to dispatch it every tick.
+//
+// Triggered by: explicit IPC command (cmd:probe-physics) or by the
+// curriculum once if the bot has been "working" but its position
+// hasn't changed by more than 4 blocks in 5 min. We add the curriculum
+// trigger in a follow-up.
+
+import { info, warn } from "../log.js";
+import { appendDiary } from "../state-store.js";
+
+function withTimeout(promise, ms, label) {
+	let timer;
+	const timeout = new Promise((_, reject) => {
+		timer = setTimeout(() => reject(new Error(`${label} timed out after ${ms / 1000}s`)), ms);
+	});
+	return Promise.race([promise, timeout]).finally(() => clearTimeout(timer));
+}
+
+async function probeForward(bot, durationMs = 2_000) {
+	const before = bot.entity.position.clone();
+	try {
+		bot.setControlState("forward", true);
+		await new Promise((r) => setTimeout(r, durationMs));
+	} finally {
+		bot.setControlState("forward", false);
+	}
+	const after = bot.entity.position;
+	const dx = after.x - before.x;
+	const dz = after.z - before.z;
+	const dist = Math.hypot(dx, dz);
+	return { before, after: after.clone(), dist, works: dist > 0.5 };
+}
+
+async function probeJump(bot) {
+	const startY = bot.entity.position.y;
+	let maxY = startY;
+	const start = Date.now();
+	try {
+		bot.setControlState("jump", true);
+		while (Date.now() - start < 800) {
+			await new Promise((r) => setTimeout(r, 50));
+			if (bot.entity.position.y > maxY) maxY = bot.entity.position.y;
+		}
+	} finally {
+		bot.setControlState("jump", false);
+	}
+	return { startY, maxY, deltaY: maxY - startY, works: maxY - startY > 0.4 };
+}
+
+async function probeDig(bot) {
+	const ds = ["sand", "dirt", "grass_block", "stone", "cobblestone", "gravel", "oak_log", "oak_leaves", "leaves"];
+	const target = bot.findBlock({
+		matching: (b) => b && b.position && ds.includes(b.name) && b.position.y >= bot.entity.position.y - 3,
+		maxDistance: 6,
+	});
+	if (!target) return { works: false, reason: "no soft block within 6 to test on" };
+
+	const tPos = target.position.clone();
+	const tName = target.name;
+	try {
+		await withTimeout(bot.lookAt(tPos.offset(0.5, 0.5, 0.5), true), 2_000, "lookAt");
+	} catch {}
+	try {
+		await withTimeout(bot.dig(target), 12_000, "dig");
+	} catch (e) {
+		return { works: false, reason: `dig threw: ${e.message}`, name: tName, at: tPos };
+	}
+	const after = bot.blockAt(tPos);
+	const gone = !after || after.name === "air" || after.name === "cave_air" || after.name === "void_air";
+	return { works: gone, before: tName, after: after?.name ?? "(none)", at: tPos };
+}
+
+export const skill = Object.freeze({
+	id: "diag.physics",
+	title: "Probe forward/jump/dig and report",
+	timeoutMs: 30_000,
+	preconditions(ctx) {
+		if (!ctx?.bot) return { ok: false, code: "no_bot", detail: "bot missing" };
+		return { ok: true };
+	},
+	async execute(ctx) {
+		const bot = ctx.bot;
+		info("action", "diag.physics: starting probe");
+
+		const fwd = await probeForward(bot);
+		info("action", `diag.physics: forward Δ=${fwd.dist.toFixed(2)} (${fwd.works ? "OK" : "BROKEN"})`);
+
+		const jmp = await probeJump(bot);
+		info("action", `diag.physics: jump ΔY=${jmp.deltaY.toFixed(2)} (${jmp.works ? "OK" : "BROKEN"})`);
+
+		const dig = await probeDig(bot);
+		info("action", `diag.physics: dig ${dig.before ?? "?"}→${dig.after ?? "?"} (${dig.works ? "OK" : "BROKEN"}: ${dig.reason ?? ""})`);
+
+		const summary = `physics probe: forward=${fwd.works ? "ok" : "BROKEN"}(Δ${fwd.dist.toFixed(1)}) jump=${jmp.works ? "ok" : "BROKEN"}(Δy${jmp.deltaY.toFixed(1)}) dig=${dig.works ? "ok" : "BROKEN"}(${dig.before ?? "no-target"}→${dig.after ?? "?"})`;
+		appendDiary(summary);
+
+		return {
+			ok: true,
+			code: "done",
+			detail: {
+				forward: fwd,
+				jump: jmp,
+				dig: dig,
+			},
+			worldDelta: {
+				probe: {
+					forwardWorks: fwd.works,
+					jumpWorks: jmp.works,
+					digWorks: dig.works,
+				},
+			},
+		};
+	},
+});
diff --git a/runtime/skills/gather-stone.js b/runtime/skills/gather-stone.js
index f64c5bc..040d294 100644
--- a/runtime/skills/gather-stone.js
+++ b/runtime/skills/gather-stone.js
@@ -109,13 +109,29 @@ export const skill = Object.freeze({
 		setMovementsForGather(bot);
 		const pickaxe = await equipBestPickaxe(bot);
 		info("action", `gather.stone: ${target.name} at ${target.position.x},${target.position.y},${target.position.z} (tool=${pickaxe ?? "fists"})`);
+		const targetPos = target.position.clone();
 		try {
+			try {
+				await withTimeout(bot.lookAt(targetPos.offset(0.5, 0.5, 0.5), true), 2_000, "lookAt(stone)");
+			} catch {}
 			await withTimeout(bot.collectBlock.collect(target), 60_000, "collectStone");
+			const after = bot.blockAt(targetPos);
+			if (after && STONE_NAMES.includes(after.name)) {
+				warn("action", `gather.stone reported ok but block still at ${targetPos.x},${targetPos.y},${targetPos.z} — silent dig failure`);
+				const key = `${targetPos.x},${targetPos.y},${targetPos.z}`;
+				blacklist.set(key, Date.now() + BLACKLIST_TTL_MS);
+				return {
+					ok: false,
+					code: "silent_dig_failure",
+					detail: "block still exists after collect — protocol/anti-cheat issue",
+					worldDelta: null,
+				};
+			}
 			return {
 				ok: true,
 				code: "done",
-				detail: { blockType: target.name, at: target.position },
-				worldDelta: { minedAt: target.position, blockType: target.name },
+				detail: { blockType: target.name, at: targetPos },
+				worldDelta: { minedAt: targetPos, blockType: target.name },
 			};
 		} catch (e) {
 			warn("action", `gather.stone failed: ${e.message}`);
diff --git a/runtime/skills/index.js b/runtime/skills/index.js
index c61f003..b2b0dca 100644
--- a/runtime/skills/index.js
+++ b/runtime/skills/index.js
@@ -26,6 +26,7 @@ import { skill as chopLogs } from "./chop-logs.js";
 import { skill as eat } from "./eat.js";
 import { skill as wander } from "./wander.js";
 import { skill as exploreFar } from "./explore-far.js";
+import { skill as diagPhysics } from "./diagnose-physics.js";
 import { skill as gatherStone } from "./gather-stone.js";
 import { skill as gatherWool } from "./gather-wool.js";
 import { skill as chooseBase } from "./choose-base.js";
@@ -62,6 +63,7 @@ register(chopLogs);
 register(eat);
 register(wander);
 register(exploreFar);
+register(diagPhysics);
 register(gatherStone);
 register(gatherWool);
 register(chooseBase);