diff --git a/src/resources/extensions/sf/detectors/gate-deadlock-classifier.js b/src/resources/extensions/sf/detectors/gate-deadlock-classifier.js
new file mode 100644
index 000000000..fe3e7e438
--- /dev/null
+++ b/src/resources/extensions/sf/detectors/gate-deadlock-classifier.js
@@ -0,0 +1,198 @@
+/**
+ * gate-deadlock-classifier.js — detect closed-loop UokGate refusals.
+ *
+ * Purpose: catch the pattern where a UokGate refuses dispatch on a unit
+ * whose purpose would advance the very requirement validation the gate
+ * is waiting for. SF cannot lift a gate that's blocking the work that
+ * would lift the gate.
+ *
+ * Concrete trigger (2026-05-17 incident): R074 inlineRuntimeGate refused
+ * inline dispatch for M048/S05 reassess-roadmap because R020 and R066
+ * were still 'active' — but reassess-roadmap + M048 slices ARE the work
+ * that validates R066. Autonomous mode stopped permanently until manual
+ * operator intervention.
+ *
+ * Consumer: periodic-runner.js default detector list and the autonomous
+ * loop's post-dispatch sweep. Filed as sf-mpa4f9k1-jm01rc.
+ */
+
+/**
+ * Minimum number of distinct refused units sharing the same gate before
+ * firing — guards against a single transient refusal triggering a
+ * false-positive deadlock report.
+ */
+export const DEADLOCK_REFUSAL_THRESHOLD = 1;
+
+/**
+ * Parse a gate refusal rationale into { gateId, refusedRequirements }.
+ *
+ * Purpose: extract the requirement identifiers a gate is waiting on so
+ * the detector can cross-reference against the refused unit's milestone
+ * coverage. The rationale format mirrors the existing inlineRuntimeGate
+ * shape: "[<gate-id>] ... R020=active R066=active ...".
+ *
+ * Returns null if the input doesn't match the expected refusal shape.
+ *
+ * @param {string} rationale
+ * @returns {{ gateId: string, refusedRequirements: string[] } | null}
+ */
+export function parseGateRefusal(rationale) {
+	if (typeof rationale !== "string" || rationale.length === 0) return null;
+	const gateMatch = rationale.match(/\[([a-z][a-z0-9-]+(?:-gate)?)\]/);
+	if (!gateMatch) return null;
+	const reqMatches = rationale.match(/\bR\d{2,}\b(?==active|=pending|=deferred)/g);
+	if (!reqMatches || reqMatches.length === 0) return null;
+	const seen = new Set();
+	const refusedRequirements = [];
+	for (const id of reqMatches) {
+		if (!seen.has(id)) {
+			seen.add(id);
+			refusedRequirements.push(id);
+		}
+	}
+	return { gateId: gateMatch[1], refusedRequirements };
+}
+
+/**
+ * Detect closed-loop gate refusals.
+ *
+ * Purpose: classify the autonomous-loop halt pattern where the refusing
+ * gate is waiting on requirements that the refused unit would advance.
+ *
+ * Inputs (ctx):
+ *  - gateRefusals?: Array<{ rationale, unitType?, unitId?, ts? }>
+ *  - requirementCoverageByMilestone?: Record<string, string[]>
+ *      (milestone id → list of R-ids in its definition_of_done / coverage)
+ *  - resolveMilestoneId?: (unitId) => string | null
+ *      (resolver for unitId → owning milestone, defaults to "M\d+" prefix)
+ *  - now?: number  — current time for throttling
+ *  - throttleState?: Map<string, number> — per-gateId last-fired ms
+ *  - options?: { throttleMs?: number, threshold?: number }
+ *
+ * Returns standard detector shape: { stuck, reason, signature }.
+ *
+ * @returns {{ stuck: boolean, reason: string, signature: object }}
+ */
+export function detectGateDeadlock(ctx = {}, options = {}) {
+	const refusals = Array.isArray(ctx.gateRefusals) ? ctx.gateRefusals : [];
+	if (refusals.length === 0) {
+		return { stuck: false, reason: "", signature: {} };
+	}
+	const coverageMap =
+		ctx.requirementCoverageByMilestone &&
+		typeof ctx.requirementCoverageByMilestone === "object"
+			? ctx.requirementCoverageByMilestone
+			: {};
+	const resolveMilestone =
+		typeof ctx.resolveMilestoneId === "function"
+			? ctx.resolveMilestoneId
+			: defaultResolveMilestone;
+	const now = options.now ?? ctx.now ?? Date.now();
+	const throttleMs = options.throttleMs ?? 60_000;
+	const threshold = options.threshold ?? DEADLOCK_REFUSAL_THRESHOLD;
+	const throttleState =
+		ctx.throttleState instanceof Map ? ctx.throttleState : null;
+
+	// Group refusals by gateId and accumulate the set of refused unit/milestone
+	// pairs whose milestone coverage overlaps with the gate's refused
+	// requirements. A deadlock fires when threshold ≥ DEADLOCK_REFUSAL_THRESHOLD
+	// distinct overlapping unit/milestone pairs are observed.
+	const byGate = new Map();
+	for (const refusal of refusals) {
+		const parsed = parseGateRefusal(refusal?.rationale);
+		if (!parsed) continue;
+		const milestoneId = resolveMilestone(refusal?.unitId ?? "");
+		if (!milestoneId) continue;
+		const milestoneCoverage = coverageMap[milestoneId];
+		if (!Array.isArray(milestoneCoverage) || milestoneCoverage.length === 0)
+			continue;
+		const overlap = parsed.refusedRequirements.filter((id) =>
+			milestoneCoverage.includes(id),
+		);
+		if (overlap.length === 0) continue;
+		let bucket = byGate.get(parsed.gateId);
+		if (!bucket) {
+			bucket = {
+				gateId: parsed.gateId,
+				deadlockedRequirements: new Set(),
+				refusedUnits: new Set(),
+				examples: [],
+			};
+			byGate.set(parsed.gateId, bucket);
+		}
+		for (const id of overlap) bucket.deadlockedRequirements.add(id);
+		bucket.refusedUnits.add(`${milestoneId}/${refusal?.unitId ?? "?"}`);
+		if (bucket.examples.length < 3) {
+			bucket.examples.push({
+				unitId: refusal?.unitId ?? null,
+				unitType: refusal?.unitType ?? null,
+				milestoneId,
+				overlap,
+				ts: refusal?.ts ?? null,
+			});
+		}
+	}
+
+	for (const bucket of byGate.values()) {
+		if (bucket.refusedUnits.size < threshold) continue;
+		if (throttleState) {
+			const last = throttleState.get(`gate-deadlock:${bucket.gateId}`);
+			if (typeof last === "number" && now - last < throttleMs) continue;
+			throttleState.set(`gate-deadlock:${bucket.gateId}`, now);
+		}
+		return {
+			stuck: true,
+			reason: "gate-deadlock",
+			signature: {
+				gateId: bucket.gateId,
+				deadlockedRequirements: [...bucket.deadlockedRequirements],
+				refusedUnits: [...bucket.refusedUnits],
+				examples: bucket.examples,
+				suggestedAction:
+					"file self-feedback (kind=gate-deadlock-detected, severity=high); " +
+					"consider audited bypass via gate-specific env or spawn-mode retry until " +
+					"deadlocked requirements validate",
+			},
+		};
+	}
+
+	return { stuck: false, reason: "", signature: {} };
+}
+
+/** Default unitId → milestoneId resolver: strip everything from first '/'. */
+function defaultResolveMilestone(unitId) {
+	if (typeof unitId !== "string" || unitId.length === 0) return null;
+	const idx = unitId.indexOf("/");
+	if (idx <= 0) return unitId.startsWith("M") ? unitId : null;
+	const head = unitId.slice(0, idx);
+	return head.startsWith("M") ? head : null;
+}
+
+/**
+ * Run the gate-deadlock classifier as a UOK verification gate.
+ *
+ * Purpose: surface the deadlock via the common gate contract so it can
+ * be wired into periodicDetectorSweepGate and post-finalize sweeps.
+ *
+ * Consumer: gate-registry-bootstrap.js and tests.
+ */
+export const gateDeadlockClassifierGate = {
+	id: "gate-deadlock-classifier",
+	type: "verification",
+	async execute(ctx = {}) {
+		const result = detectGateDeadlock(ctx, ctx.options ?? {});
+		if (result.stuck) {
+			return {
+				outcome: "fail",
+				failureClass: "verification",
+				rationale: `gate-deadlock on ${result.signature.gateId}: refused units ${result.signature.refusedUnits.join(", ")} need ${result.signature.deadlockedRequirements.join(", ")} which the gate is waiting for`,
+				findings: result.signature,
+			};
+		}
+		return {
+			outcome: "pass",
+			failureClass: null,
+			rationale: "no gate-deadlock pattern",
+		};
+	},
+};
diff --git a/src/resources/extensions/sf/detectors/index.js b/src/resources/extensions/sf/detectors/index.js
index b67851686..7a9b28e6f 100644
--- a/src/resources/extensions/sf/detectors/index.js
+++ b/src/resources/extensions/sf/detectors/index.js
@@ -7,6 +7,7 @@
 
 export { artifactFlapGate } from "./artifact-flap.js";
 export { crashLoopGate } from "./crash-loop-classifier.js";
+export { gateDeadlockClassifierGate } from "./gate-deadlock-classifier.js";
 export { periodicDetectorSweepGate } from "./periodic-runner.js";
 export { productionPlateauGate } from "./production-plateau.js";
 export { repeatedFeedbackKindGate } from "./repeated-feedback-kind.js";
diff --git a/src/resources/extensions/sf/tests/detector-gate-deadlock-classifier.test.mjs b/src/resources/extensions/sf/tests/detector-gate-deadlock-classifier.test.mjs
new file mode 100644
index 000000000..3a20e0b06
--- /dev/null
+++ b/src/resources/extensions/sf/tests/detector-gate-deadlock-classifier.test.mjs
@@ -0,0 +1,194 @@
+/**
+ * detector-gate-deadlock-classifier.test.mjs — tests for the gate-deadlock
+ * Wiggums detector that fires when a UokGate refuses dispatch on a unit
+ * whose milestone coverage would advance the requirements the gate is
+ * waiting for.
+ *
+ * Covers parseGateRefusal helper, the detector function across the
+ * deadlock-pattern × purpose-match × throttle × empty-input matrix, and
+ * the UokGate wrapper contract per ADR-0075.
+ */
+
+import { describe, expect, it } from "vitest";
+import {
+	DEADLOCK_REFUSAL_THRESHOLD,
+	detectGateDeadlock,
+	gateDeadlockClassifierGate,
+	parseGateRefusal,
+} from "../detectors/gate-deadlock-classifier.js";
+
+const INLINE_REFUSAL =
+	"[inline-runtime-gate] inline dispatch refused: R020=active R066=active both must be 'validated' or set SF_INLINE_DISPATCH=1 for audited bypass";
+
+// ─── parseGateRefusal ──────────────────────────────────────────────────────
+
+describe("parseGateRefusal", () => {
+	it("extracts gate id and refused requirements from inline refusal", () => {
+		const parsed = parseGateRefusal(INLINE_REFUSAL);
+		expect(parsed).not.toBeNull();
+		expect(parsed.gateId).toBe("inline-runtime-gate");
+		expect(parsed.refusedRequirements).toEqual(["R020", "R066"]);
+	});
+
+	it("dedupes repeated requirement ids", () => {
+		const parsed = parseGateRefusal(
+			"[some-gate] refused: R020=active R020=active R066=pending",
+		);
+		expect(parsed.refusedRequirements).toEqual(["R020", "R066"]);
+	});
+
+	it("returns null when no requirement ids are present", () => {
+		expect(parseGateRefusal("[some-gate] generic failure")).toBeNull();
+	});
+
+	it("returns null when no gate id bracket is present", () => {
+		expect(parseGateRefusal("R020=active R066=active no gate")).toBeNull();
+	});
+
+	it("returns null on empty / non-string input", () => {
+		expect(parseGateRefusal("")).toBeNull();
+		expect(parseGateRefusal(null)).toBeNull();
+		expect(parseGateRefusal(undefined)).toBeNull();
+	});
+});
+
+// ─── detectGateDeadlock ────────────────────────────────────────────────────
+
+describe("detectGateDeadlock", () => {
+	it("returns not-stuck for empty refusal list", () => {
+		expect(detectGateDeadlock({ gateRefusals: [] })).toEqual({
+			stuck: false,
+			reason: "",
+			signature: {},
+		});
+	});
+
+	it("fires when refused unit's milestone covers the deadlocked requirement", () => {
+		const result = detectGateDeadlock({
+			gateRefusals: [
+				{
+					rationale: INLINE_REFUSAL,
+					unitType: "reassess-roadmap",
+					unitId: "M048/S05",
+					ts: "2026-05-17T18:24:00Z",
+				},
+			],
+			requirementCoverageByMilestone: { M048: ["R066", "R078"] },
+		});
+		expect(result.stuck).toBe(true);
+		expect(result.reason).toBe("gate-deadlock");
+		expect(result.signature.gateId).toBe("inline-runtime-gate");
+		expect(result.signature.deadlockedRequirements).toEqual(["R066"]);
+		expect(result.signature.refusedUnits).toEqual(["M048/M048/S05"]);
+		expect(result.signature.suggestedAction).toMatch(/audited bypass/);
+	});
+
+	it("does NOT fire when refused unit's milestone covers none of the gate requirements", () => {
+		const result = detectGateDeadlock({
+			gateRefusals: [
+				{
+					rationale: INLINE_REFUSAL,
+					unitType: "execute-task",
+					unitId: "M010/S04/T01",
+				},
+			],
+			requirementCoverageByMilestone: { M010: ["R015"] },
+		});
+		expect(result.stuck).toBe(false);
+	});
+
+	it("does NOT fire when milestone coverage map is empty for the unit's milestone", () => {
+		const result = detectGateDeadlock({
+			gateRefusals: [
+				{ rationale: INLINE_REFUSAL, unitId: "M048/S05" },
+			],
+			requirementCoverageByMilestone: {},
+		});
+		expect(result.stuck).toBe(false);
+	});
+
+	it("throttles repeat firings for the same gate within throttleMs", () => {
+		const throttleState = new Map();
+		const ctx = {
+			gateRefusals: [
+				{ rationale: INLINE_REFUSAL, unitId: "M048/S05" },
+			],
+			requirementCoverageByMilestone: { M048: ["R066"] },
+			throttleState,
+		};
+		const first = detectGateDeadlock(ctx, { now: 1000 });
+		expect(first.stuck).toBe(true);
+		const second = detectGateDeadlock(ctx, { now: 5000 });
+		expect(second.stuck).toBe(false);
+		const third = detectGateDeadlock(ctx, { now: 1000 + 70_000 });
+		expect(third.stuck).toBe(true);
+	});
+
+	it("custom resolveMilestoneId overrides the default M-prefix resolver", () => {
+		const result = detectGateDeadlock({
+			gateRefusals: [
+				{ rationale: INLINE_REFUSAL, unitId: "slice-xyz" },
+			],
+			requirementCoverageByMilestone: { CUSTOM: ["R020"] },
+			resolveMilestoneId: () => "CUSTOM",
+		});
+		expect(result.stuck).toBe(true);
+		expect(result.signature.deadlockedRequirements).toEqual(["R020"]);
+	});
+
+	it("captures at most 3 example refusals in signature", () => {
+		const refusals = ["M048/S01", "M048/S02", "M048/S03", "M048/S04"].map(
+			(unitId) => ({ rationale: INLINE_REFUSAL, unitId }),
+		);
+		const result = detectGateDeadlock({
+			gateRefusals: refusals,
+			requirementCoverageByMilestone: { M048: ["R066"] },
+		});
+		expect(result.stuck).toBe(true);
+		expect(result.signature.examples.length).toBeLessThanOrEqual(3);
+		expect(result.signature.refusedUnits.length).toBe(4);
+	});
+});
+
+// ─── gateDeadlockClassifierGate (UokGate wrapper, ADR-0075) ────────────────
+
+describe("gateDeadlockClassifierGate", () => {
+	it("exports the ADR-0075 gate contract shape", () => {
+		expect(gateDeadlockClassifierGate.id).toBe("gate-deadlock-classifier");
+		expect(gateDeadlockClassifierGate.type).toBe("verification");
+		expect(typeof gateDeadlockClassifierGate.execute).toBe("function");
+	});
+
+	it("execute returns pass when no deadlock pattern", async () => {
+		const result = await gateDeadlockClassifierGate.execute({
+			gateRefusals: [],
+		});
+		expect(result.outcome).toBe("pass");
+		expect(result.failureClass).toBeNull();
+		expect(result.rationale).toContain("no gate-deadlock");
+	});
+
+	it("execute returns fail with structured findings when deadlock detected", async () => {
+		const result = await gateDeadlockClassifierGate.execute({
+			gateRefusals: [
+				{ rationale: INLINE_REFUSAL, unitId: "M048/S05" },
+			],
+			requirementCoverageByMilestone: { M048: ["R066"] },
+		});
+		expect(result.outcome).toBe("fail");
+		expect(result.failureClass).toBe("verification");
+		expect(result.rationale).toContain("inline-runtime-gate");
+		expect(result.rationale).toContain("R066");
+		expect(result.findings.gateId).toBe("inline-runtime-gate");
+		expect(result.findings.deadlockedRequirements).toEqual(["R066"]);
+	});
+});
+
+// ─── threshold sanity ──────────────────────────────────────────────────────
+
+describe("threshold export", () => {
+	it("DEADLOCK_REFUSAL_THRESHOLD is a positive integer", () => {
+		expect(DEADLOCK_REFUSAL_THRESHOLD).toBeGreaterThanOrEqual(1);
+		expect(Number.isInteger(DEADLOCK_REFUSAL_THRESHOLD)).toBe(true);
+	});
+});
diff --git a/src/resources/extensions/sf/uok/gate-registry-bootstrap.js b/src/resources/extensions/sf/uok/gate-registry-bootstrap.js
index 5bc136ef4..04afc062c 100644
--- a/src/resources/extensions/sf/uok/gate-registry-bootstrap.js
+++ b/src/resources/extensions/sf/uok/gate-registry-bootstrap.js
@@ -12,6 +12,7 @@ import { artifactFlapGate } from "../detectors/artifact-flap.js";
 import { staleLockGate } from "../detectors/stale-lock.js";
 import { periodicDetectorSweepGate } from "../detectors/periodic-runner.js";
 import { serverDirectionDriftGate } from "../detectors/server-direction-drift.js";
+import { gateDeadlockClassifierGate } from "../detectors/gate-deadlock-classifier.js";
 import { inlineRuntimeGate } from "./inline-runtime-gate.js";
 
 /**
@@ -45,5 +46,9 @@ registry.register(staleLockGate);
 registry.register(serverDirectionDriftGate);
 registry.register(periodicDetectorSweepGate);
 registry.register(inlineRuntimeGate);
+// gate-deadlock-classifier — fires when a UokGate refuses dispatch on a
+// unit whose milestone coverage would advance the gate's deadlocked
+// requirements. Closes the R074 self-deadlock pattern (sf-mpa4f9k1).
+registry.register(gateDeadlockClassifierGate);
 
 export { registry as gateRegistry };