diff --git a/src/resources/extensions/sf/auto-model-selection.js b/src/resources/extensions/sf/auto-model-selection.js
index 2f71ab4f5..03a79ab50 100644
--- a/src/resources/extensions/sf/auto-model-selection.js
+++ b/src/resources/extensions/sf/auto-model-selection.js
@@ -69,6 +69,59 @@ function readEnabledModels() {
 		return undefined; // settings missing or unreadable → no allowlist constraint
 	}
 }
+
+/**
+ * Return true for best-effort/free-tier model routes.
+ *
+ * Purpose: keep autonomous coding work on reliable paid/subscription routes by
+ * default; free SKUs are useful for experiments but have weaker availability and
+ * tool-loop guarantees.
+ *
+ * Consumer: selectAndApplyModel before dynamic routing and fallback hooks build
+ * their candidate pools.
+ */
+export function isFreeTierModelRoute(provider, modelId) {
+	const text = `${provider ?? ""}/${modelId ?? ""}`.toLowerCase();
+	return /(^|[-_:/\s])free($|[-_:/\s])/i.test(text);
+}
+
+/**
+ * Return true when a unit may use best-effort/free-tier routes.
+ *
+ * Purpose: allow cheap models on supporting work while keeping repo-changing
+ * worker and verification units on reliable routes.
+ *
+ * Consumer: filterAutoRoutableModels in autonomous model selection.
+ */
+export function allowsFreeTierAutoRoute(unitType) {
+	const type = String(unitType ?? "");
+	return (
+		type === "research-milestone" ||
+		type === "research-slice" ||
+		type === "discuss-milestone" ||
+		type === "triage" ||
+		type.startsWith("triage-") ||
+		type.startsWith("hook/")
+	);
+}
+
+/**
+ * Remove free-tier routes from autonomous auto-selection unless the operator
+ * explicitly opts in.
+ *
+ * Purpose: prevent SF from silently choosing routes such as
+ * openrouter/qwen/qwen3-coder:free as the main autonomous worker for production
+ * repo changes.
+ *
+ * Consumer: dynamic routing candidate assembly in selectAndApplyModel.
+ */
+export function filterAutoRoutableModels(models, routingConfig, unitType) {
+	if (routingConfig?.allow_free_models === true) return models;
+	if (allowsFreeTierAutoRoute(unitType)) return models;
+	return models.filter(
+		(model) => !isFreeTierModelRoute(model.provider, model.id),
+	);
+}
 /**
  * Thrown when the model-policy gate rejects every candidate model for a unit
  * dispatch (#4959 / #4681 / #4850).  The auto-loop catches this specifically
@@ -438,7 +491,9 @@ export async function selectAndApplyModel(
 		}
 		let effectiveModelConfig = modelConfig;
 		let routingTierLabel = "";
-		let routingEligibleModels = availableModels;
+		let routingEligibleModels = isAutoMode
+			? filterAutoRoutableModels(availableModels, routingConfig, unitType)
+			: availableModels;
 		const taskMetadataForPolicy =
 			unitType === "execute-task"
 				? extractTaskMetadata(unitId, basePath)
diff --git a/src/resources/extensions/sf/auto-timers.js b/src/resources/extensions/sf/auto-timers.js
index c63a613fe..b186a6bb1 100644
--- a/src/resources/extensions/sf/auto-timers.js
+++ b/src/resources/extensions/sf/auto-timers.js
@@ -8,6 +8,7 @@
 import { saveActivityLog } from "./activity-log.js";
 import { resolveAgentEndCancelled } from "./auto/resolve.js";
 import { detectWorkingTreeActivity } from "./auto-supervisor.js";
+import { blockModel } from "./blocked-models.js";
 import { recoverTimedOutUnit } from "./auto-timeout-recovery.js";
 import {
 	clearInFlightTools,
@@ -270,6 +271,24 @@ export function startUnitSupervision(sctx) {
 				}
 				if (decision.action === "fail") {
 					if (getInFlightToolCount() > 0) return;
+					const failedModel = s.currentUnitModel;
+					if (
+						decision.reason === "zero-progress" &&
+						failedModel?.provider &&
+						failedModel?.id
+					) {
+						blockModel(
+							s.basePath,
+							failedModel.provider,
+							failedModel.id,
+							`zero-progress on ${unitType} ${unitId}`,
+							{ expiresAt: Date.now() + 60 * 60 * 1000 },
+						);
+						ctx.ui.notify(
+							`Temporarily blocked ${failedModel.provider}/${failedModel.id} after zero-progress on ${unitType} ${unitId}; retry will choose a fallback.`,
+							"warning",
+						);
+					}
 					await closeoutUnit(
 						ctx,
 						s.basePath,
diff --git a/src/resources/extensions/sf/self-feedback-drain.js b/src/resources/extensions/sf/self-feedback-drain.js
index 5785b720a..b14da308a 100644
--- a/src/resources/extensions/sf/self-feedback-drain.js
+++ b/src/resources/extensions/sf/self-feedback-drain.js
@@ -267,6 +267,26 @@ export function buildInlineFixPrompt(entries) {
 		"When every entry has a decision, say: Self-feedback triage complete.",
 	].join("\n");
 }
+
+/**
+ * Return true when the current surface cannot reliably consume interactive
+ * follow-up turns.
+ *
+ * Purpose: web/RPC and headless autonomous runs need self-feedback repair to
+ * leave the main worker alone; injecting a hidden follow-up prompt into those
+ * surfaces can steal the next autonomous unit and trip the zero-progress guard.
+ *
+ * Consumer: dispatchSelfFeedbackInlineFixIfNeeded when choosing between a
+ * headless triage subprocess and an interactive `pi.sendMessage` follow-up.
+ */
+export function isMachineSelfFeedbackSurface(env = process.env) {
+	return (
+		env.SF_HEADLESS === "1" ||
+		env.SF_WEB_BRIDGE_TUI === "1" ||
+		env.SF_WEB_AUTO_START_AUTONOMOUS === "1"
+	);
+}
+
 /**
  * Dispatch a focused inline-fix turn for unresolved high/critical self-feedback.
  *
@@ -312,7 +332,7 @@ export function dispatchSelfFeedbackInlineFixIfNeeded(basePath, ctx, pi) {
 	// pipeline through SF's own subprocess machinery (router-resolved model,
 	// watchdog, trust gate). Fire-and-forget: the autonomous loop will see the
 	// resolved entries via DB on the next iteration's gate check.
-	if (process.env.SF_HEADLESS === "1") {
+	if (isMachineSelfFeedbackSurface()) {
 		ctx.ui.notify(
 			`Dispatching self-feedback inline fix via 'sf headless triage --apply' for ${ids.length} high/critical entr${ids.length === 1 ? "y" : "ies"} (headless surface).`,
 			"warning",
diff --git a/src/resources/extensions/sf/tests/enabled-models-fallback.test.mjs b/src/resources/extensions/sf/tests/enabled-models-fallback.test.mjs
index 436f769d2..b21d9f3ae 100644
--- a/src/resources/extensions/sf/tests/enabled-models-fallback.test.mjs
+++ b/src/resources/extensions/sf/tests/enabled-models-fallback.test.mjs
@@ -20,7 +20,11 @@ import { afterEach, describe, test } from "vitest";
 
 import { isModelInEnabledList } from "../preferences-models.js";
 import "../preferences.js";
-import { selectAndApplyModel } from "../auto-model-selection.js";
+import {
+	allowsFreeTierAutoRoute,
+	filterAutoRoutableModels,
+	selectAndApplyModel,
+} from "../auto-model-selection.js";
 
 // ── Test environment setup ───────────────────────────────────────────────────
 
@@ -232,6 +236,41 @@ describe("isModelInEnabledList", () => {
 	});
 });
 
+describe("free-tier autonomous routing policy", () => {
+	const PAID = makeCandidate("kimi-coding", "kimi-k2.6");
+	const FREE = makeCandidate("openrouter", "qwen/qwen3-coder:free");
+
+	test("main_worker_units_exclude_free_tier_routes_by_default", () => {
+		const filtered = filterAutoRoutableModels(
+			[FREE, PAID],
+			{ allow_free_models: false },
+			"execute-task",
+		);
+
+		assert.deepEqual(
+			filtered.map((m) => `${m.provider}/${m.id}`),
+			["kimi-coding/kimi-k2.6"],
+		);
+	});
+
+	test("secondary_units_may_use_free_tier_routes", () => {
+		assert.equal(allowsFreeTierAutoRoute("research-slice"), true);
+		assert.equal(allowsFreeTierAutoRoute("triage"), true);
+		assert.equal(allowsFreeTierAutoRoute("execute-task"), false);
+
+		const filtered = filterAutoRoutableModels(
+			[FREE, PAID],
+			{},
+			"research-slice",
+		);
+
+		assert.deepEqual(
+			filtered.map((m) => `${m.provider}/${m.id}`),
+			["openrouter/qwen/qwen3-coder:free", "kimi-coding/kimi-k2.6"],
+		);
+	});
+});
+
 // ── Part 2: fallback chain respects enabledModels ─────────────────────────────
 //
 // preferences.yaml pins execution chain to:
diff --git a/src/resources/extensions/sf/tests/self-feedback-drain.test.mjs b/src/resources/extensions/sf/tests/self-feedback-drain.test.mjs
index 9af57f07c..85d833e5e 100644
--- a/src/resources/extensions/sf/tests/self-feedback-drain.test.mjs
+++ b/src/resources/extensions/sf/tests/self-feedback-drain.test.mjs
@@ -5,6 +5,7 @@ import { afterEach, describe, expect, test } from "vitest";
 import {
 	buildInlineFixPrompt,
 	filterTriageCandidatesByProviderPolicy,
+	isMachineSelfFeedbackSurface,
 	rankTriageModelsViaRouter,
 	runTriage,
 	selectInlineFixCandidates,
@@ -361,6 +362,28 @@ describe("buildInlineFixPrompt", () => {
 	});
 });
 
+describe("isMachineSelfFeedbackSurface", () => {
+	test("treats web RPC bridge as machine surface even before SF_HEADLESS is set", () => {
+		expect(
+			isMachineSelfFeedbackSurface({
+				SF_WEB_BRIDGE_TUI: "1",
+			}),
+		).toBe(true);
+	});
+
+	test("treats server auto-start as machine surface", () => {
+		expect(
+			isMachineSelfFeedbackSurface({
+				SF_WEB_AUTO_START_AUTONOMOUS: "1",
+			}),
+		).toBe(true);
+	});
+
+	test("keeps ordinary interactive sessions on follow-up path", () => {
+		expect(isMachineSelfFeedbackSurface({})).toBe(false);
+	});
+});
+
 describe("runTriage (dependency-injected)", () => {
 	test("returns ok+content on success and flags clean-finish from terminator", async () => {
 		const fakeMessage = {