diff --git a/src/resources/extensions/sf/auto-bootstrap-context.js b/src/resources/extensions/sf/auto-bootstrap-context.js
index 129490dde..334bdc8ad 100644
--- a/src/resources/extensions/sf/auto-bootstrap-context.js
+++ b/src/resources/extensions/sf/auto-bootstrap-context.js
@@ -22,6 +22,7 @@ const AUTO_BOOTSTRAP_SF_SPEC_FILES = [
 	".sf/STATE.md",
 	".sf/PRINCIPLES.md",
 	".sf/TASTE.md",
+	".sf/preferences.yaml",
 	".sf/PREFERENCES.md",
 	".sf/ANTI-GOALS.md",
 	".sf/CODEBASE.md",
diff --git a/src/resources/extensions/sf/auto-model-selection.js b/src/resources/extensions/sf/auto-model-selection.js
index 31a36a047..e2107e1f6 100644
--- a/src/resources/extensions/sf/auto-model-selection.js
+++ b/src/resources/extensions/sf/auto-model-selection.js
@@ -837,7 +837,7 @@ export function resolveModelId(modelId, availableModels, currentProvider) {
 	// Extension providers (e.g. claude-code) expose the same model IDs as their
 	// upstream API providers but route through a subprocess with different
 	// context, tool visibility, and cost characteristics (#2905).  Bare IDs in
-	// PREFERENCES.md must resolve to the canonical API provider, not to an
+	// preferences.yaml must resolve to the canonical API provider, not to an
 	// extension wrapper that happens to be the current session provider.
 	const candidates = availableModels.filter((m) =>
 		matchesBareModelId(m.id, modelId),
diff --git a/src/resources/extensions/sf/auto-start.js b/src/resources/extensions/sf/auto-start.js
index 6e1268446..0edc23b41 100644
--- a/src/resources/extensions/sf/auto-start.js
+++ b/src/resources/extensions/sf/auto-start.js
@@ -360,7 +360,7 @@ export async function bootstrapAutoSession(
 	//
 	// Precedence:
 	// 1) Explicit session override via /model (this session)
-	// 2) SF model preferences from PREFERENCES.md (validated against live auth)
+	// 2) SF model preferences from preferences.yaml (validated against live auth)
 	// 3) Current session model from settings/session restore (if provider ready)
 	//
 	// This preserves #3517 defaults while honoring explicit runtime model
@@ -368,7 +368,7 @@ export async function bootstrapAutoSession(
 	//
 	// Exception (#4122): when the session provider is a custom provider declared
 	// in ~/.sf/agent/models.json (Ollama, vLLM, OpenAI-compatible proxy, etc.),
-	// PREFERENCES.md is skipped entirely. PREFERENCES.md cannot reference custom
+	// preferences.yaml is skipped entirely. preferences.yaml cannot reference custom
 	// providers, so honoring it would silently reroute autonomous mode to a built-in
 	// provider the user is not logged into and surface as "Not logged in · Please
 	// run /login" before pausing and resetting to claude-code/claude-sonnet-4-6.
@@ -380,7 +380,7 @@ export async function bootstrapAutoSession(
 		? null
 		: resolveDefaultSessionModel(ctx.model?.provider);
 	// Validate the preferred model against the live registry + provider auth so
-	// an unconfigured PREFERENCES.md entry (no API key / OAuth) can't become the
+	// an unconfigured preferences.yaml entry (no API key / OAuth) can't become the
 	// start-model snapshot. Without this, every subsequent unit would try to
 	// fall back to an unusable model.
 	let validatedPreferredModel;
@@ -396,7 +396,7 @@ export async function bootstrapAutoSession(
 			validatedPreferredModel = { provider: match.provider, id: match.id };
 		} else {
 			ctx.ui.notify(
-				`Preferred model ${preferredModel.provider}/${preferredModel.id} from PREFERENCES.md is not configured; falling back to session default.`,
+				`Preferred model ${preferredModel.provider}/${preferredModel.id} from preferences.yaml is not configured; falling back to session default.`,
 				"warning",
 			);
 		}
diff --git a/src/resources/extensions/sf/auto-worktree.js b/src/resources/extensions/sf/auto-worktree.js
index 841ad3383..8047cbe92 100644
--- a/src/resources/extensions/sf/auto-worktree.js
+++ b/src/resources/extensions/sf/auto-worktree.js
@@ -70,8 +70,8 @@ import {
 } from "./worktree-manager.js";
 
 const sfHome = process.env.SF_HOME || join(homedir(), ".sf");
-const PROJECT_PREFERENCES_FILE = "PREFERENCES.md";
-const LEGACY_PROJECT_PREFERENCES_FILE = "preferences.md";
+const PROJECT_PREFERENCES_FILE = "preferences.yaml";
+const LEGACY_PREFERENCES_FILES = ["PREFERENCES.md", "preferences.md"];
 // ─── Shared Constants & Helpers ─────────────────────────────────────────────
 /**
  * Root-level .sf/ state files synced between worktree and project root.
@@ -552,17 +552,13 @@ export function syncSfStateToWorktree(mainBasePath, worktreePath_) {
 		}
 	}
 	// Forward-sync project preferences from project root to worktree (additive only).
-	// Prefer the canonical uppercase file name, but keep the legacy lowercase
-	// fallback so older repos still work on case-sensitive filesystems.
+	// Prefer the canonical yaml file, but keep legacy md fallbacks so older repos still work.
 	{
 		const worktreeHasPreferences =
 			existsSync(join(wtSf, PROJECT_PREFERENCES_FILE)) ||
-			existsSync(join(wtSf, LEGACY_PROJECT_PREFERENCES_FILE));
+			LEGACY_PREFERENCES_FILES.some((f) => existsSync(join(wtSf, f)));
 		if (!worktreeHasPreferences) {
-			for (const file of [
-				PROJECT_PREFERENCES_FILE,
-				LEGACY_PROJECT_PREFERENCES_FILE,
-			]) {
+			for (const file of [PROJECT_PREFERENCES_FILE, ...LEGACY_PREFERENCES_FILES]) {
 				const src = join(mainSf, file);
 				const dst = join(wtSf, file);
 				if (existsSync(src)) {
@@ -1194,19 +1190,24 @@ function copyPlanningArtifacts(srcBase, wtPath) {
 	]) {
 		safeCopy(join(srcSf, file), join(dstSf, file), { force: true });
 	}
-	// Seed canonical PREFERENCES.md when available; fall back to legacy lowercase.
+	// Seed canonical preferences.yaml when available; fall back to legacy md files.
 	if (existsSync(join(srcSf, PROJECT_PREFERENCES_FILE))) {
 		safeCopy(
 			join(srcSf, PROJECT_PREFERENCES_FILE),
 			join(dstSf, PROJECT_PREFERENCES_FILE),
 			{ force: true },
 		);
-	} else if (existsSync(join(srcSf, LEGACY_PROJECT_PREFERENCES_FILE))) {
-		safeCopy(
-			join(srcSf, LEGACY_PROJECT_PREFERENCES_FILE),
-			join(dstSf, LEGACY_PROJECT_PREFERENCES_FILE),
-			{ force: true },
-		);
+	} else {
+		for (const legacyFile of LEGACY_PREFERENCES_FILES) {
+			if (existsSync(join(srcSf, legacyFile))) {
+				safeCopy(
+					join(srcSf, legacyFile),
+					join(dstSf, legacyFile),
+					{ force: true },
+				);
+				break;
+			}
+		}
 	}
 	// Shared WAL (R012): worktrees use the project root's DB directly.
 	// No longer copy sf.db into the worktree — the DB path resolver in
diff --git a/src/resources/extensions/sf/auto.js b/src/resources/extensions/sf/auto.js
index 0bb4cdb39..8f8874991 100644
--- a/src/resources/extensions/sf/auto.js
+++ b/src/resources/extensions/sf/auto.js
@@ -1501,6 +1501,7 @@ export async function startAuto(ctx, pi, base, verboseMode, options) {
 		ctx.ui.notify(
 			"Switched to Build mode — starting autonomous execution.",
 			"info",
+			{ noticeKind: NOTICE_KIND.USER_VISIBLE },
 		);
 	}
 	// On a *fresh* start, drop any stale active-tool baseline left by a prior
@@ -1526,7 +1527,9 @@ export async function startAuto(ctx, pi, base, verboseMode, options) {
 	base = escapeStaleWorktree(base);
 	const startupFixes = healAutoStartupRuntime(base);
 	for (const fix of startupFixes) {
-		ctx.ui.notify(`Startup self-heal: ${fix}.`, "info");
+		ctx.ui.notify(`Startup self-heal: ${fix}.`, "info", {
+			noticeKind: NOTICE_KIND.SYSTEM_NOTICE,
+		});
 	}
 	const freshStartAssessment =
 		interruptedAssessment ?? (await assessInterruptedSession(base));
@@ -1537,6 +1540,10 @@ export async function startAuto(ctx, pi, base, verboseMode, options) {
 				? `Another autonomous mode session (PID ${pid}) appears to be running.\nStop it with \`kill ${pid}\` before starting a new session.`
 				: "Another autonomous mode session appears to be running.",
 			"error",
+			{
+				noticeKind: NOTICE_KIND.BLOCKING_NOTICE,
+				dedupe_key: "auto-start-concurrent-session-blocked",
+			},
 		);
 		return;
 	}
diff --git a/src/resources/extensions/sf/codebase-generator.js b/src/resources/extensions/sf/codebase-generator.js
index bbf0f8d06..b3c7e807f 100644
--- a/src/resources/extensions/sf/codebase-generator.js
+++ b/src/resources/extensions/sf/codebase-generator.js
@@ -315,7 +315,7 @@ function inferProjectKnowledge(files) {
 		}
 		pushUnique(
 			verificationCommands,
-			"pytest or the project quality command (lint + type + test stack from .sf/PREFERENCES.md)",
+			"pytest or the project quality command (lint + type + test stack from .sf/preferences.yaml)",
 		);
 		pushUnique(skillNeeds, "Python packaging, typing, and tests");
 	}
diff --git a/src/resources/extensions/sf/commands-codebase.js b/src/resources/extensions/sf/commands-codebase.js
index 21d6f449d..0b5d2fe27 100644
--- a/src/resources/extensions/sf/commands-codebase.js
+++ b/src/resources/extensions/sf/commands-codebase.js
@@ -23,7 +23,7 @@ const USAGE =
 	"  help                                               — Show this help\n\n" +
 	"With no subcommand, shows stats if a map exists or help if not.\n" +
 	"SF also refreshes CODEBASE.md automatically before prompt injection and after completed units when tracked files change.\n\n" +
-	"Configure defaults via preferences.md:\n" +
+	"Configure defaults via preferences.yaml:\n" +
 	"  codebase:\n" +
 	'    exclude_patterns: ["docs/", "fixtures/"]\n' +
 	"    max_files: 1000\n" +
diff --git a/src/resources/extensions/sf/commands-prefs-wizard.js b/src/resources/extensions/sf/commands-prefs-wizard.js
index cd21905a7..277624909 100644
--- a/src/resources/extensions/sf/commands-prefs-wizard.js
+++ b/src/resources/extensions/sf/commands-prefs-wizard.js
@@ -39,6 +39,26 @@ function extractBodyAfterFrontmatter(content) {
 	const afterFrontmatter = content.slice(closingIdx + 4);
 	return afterFrontmatter.trim() ? afterFrontmatter : null;
 }
+/**
+ * Serialize prefs and save to path, using format appropriate for file type.
+ * .yaml → raw YAML (no --- markers, no Markdown body)
+ * .md  → YAML frontmatter + preserved or default Markdown body
+ */
+async function savePreferencesFile(path, prefs) {
+	prefs.version = prefs.version || 1;
+	const yaml = serializePreferencesToFrontmatter(prefs);
+	if (path.endsWith(".yaml")) {
+		await saveFile(path, yaml);
+		return;
+	}
+	let body =
+		"\n# SF Skill Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full field documentation and examples.\n";
+	if (existsSync(path)) {
+		const preserved = extractBodyAfterFrontmatter(readFileSync(path, "utf-8"));
+		if (preserved) body = preserved;
+	}
+	await saveFile(path, `---\n${yaml}---${body}`);
+}
 // ─── Numeric validation helpers ──────────────────────────────────────────────
 /** Parse a string as a non-negative integer, or return null on failure. */
 function tryParseInteger(val) {
@@ -138,24 +158,14 @@ export async function handleImportClaude(ctx, scope) {
 	const readPrefs = () => {
 		if (!existsSync(path)) return { version: 1 };
 		const content = readFileSync(path, "utf-8");
-		const [frontmatterLines] = splitFrontmatter(content);
-		return frontmatterLines
-			? parseFrontmatterMap(frontmatterLines)
-			: { version: 1 };
-	};
-	const writePrefs = async (prefs) => {
-		prefs.version = prefs.version || 1;
-		const frontmatter = serializePreferencesToFrontmatter(prefs);
-		let body =
-			"\n# SF Skill Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full field documentation and examples.\n";
-		if (existsSync(path)) {
-			const preserved = extractBodyAfterFrontmatter(
-				readFileSync(path, "utf-8"),
-			);
-			if (preserved) body = preserved;
+		if (path.endsWith(".yaml")) {
+			const [frontmatterLines] = splitFrontmatter(`---\n${content}\n---`);
+			return frontmatterLines ? parseFrontmatterMap(frontmatterLines) : { version: 1 };
 		}
-		await saveFile(path, `---\n${frontmatter}---${body}`);
+		const [frontmatterLines] = splitFrontmatter(content);
+		return frontmatterLines ? parseFrontmatterMap(frontmatterLines) : { version: 1 };
 	};
+	const writePrefs = async (prefs) => savePreferencesFile(path, prefs);
 	await runClaudeImportFlow(ctx, scope, readPrefs, writePrefs);
 }
 export async function handlePrefsMode(ctx, scope) {
@@ -169,17 +179,7 @@ export async function handlePrefsMode(ctx, scope) {
 			: loadGlobalSFPreferences();
 	const prefs = existing?.preferences ? { ...existing.preferences } : {};
 	await configureMode(ctx, prefs);
-	// Serialize and save
-	prefs.version = prefs.version || 1;
-	const frontmatter = serializePreferencesToFrontmatter(prefs);
-	let body =
-		"\n# SF Skill Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full field documentation and examples.\n";
-	if (existsSync(path)) {
-		const preserved = extractBodyAfterFrontmatter(readFileSync(path, "utf-8"));
-		if (preserved) body = preserved;
-	}
-	const content = `---\n${frontmatter}---${body}`;
-	await saveFile(path, content);
+	await savePreferencesFile(path, prefs);
 	await ctx.waitForIdle();
 	await ctx.reload();
 	ctx.ui.notify(`Saved ${scope} preferences to ${path}`, "info");
@@ -832,26 +832,18 @@ export async function handlePrefsWizard(ctx, scope) {
 			await configureNotifications(ctx, prefs);
 		else if (choice.startsWith("Advanced")) await configureAdvanced(ctx, prefs);
 	}
-	// ─── Serialize to frontmatter ───────────────────────────────────────────
-	prefs.version = prefs.version || 1;
-	const frontmatter = serializePreferencesToFrontmatter(prefs);
-	// Preserve existing body content (everything after closing ---)
-	let body =
-		"\n# SF Skill Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full field documentation and examples.\n";
-	if (existsSync(path)) {
-		const preserved = extractBodyAfterFrontmatter(readFileSync(path, "utf-8"));
-		if (preserved) body = preserved;
-	}
-	const content = `---\n${frontmatter}---${body}`;
-	await saveFile(path, content);
+	// ─── Serialize and save ─────────────────────────────────────────────────
+	await savePreferencesFile(path, prefs);
 	await ctx.waitForIdle();
 	await ctx.reload();
 	ctx.ui.notify(`Saved ${scope} preferences to ${path}`, "info");
 }
 export async function ensurePreferencesFile(path, ctx, scope) {
 	if (!existsSync(path)) {
+		// Use yaml template for .yaml paths, markdown template for legacy .md paths
+		const templateFile = path.endsWith(".yaml") ? "preferences.yaml" : "PREFERENCES.md";
 		const template = await loadFile(
-			join(import.meta.dirname, "templates", "PREFERENCES.md"),
+			join(import.meta.dirname, "templates", templateFile),
 		);
 		if (!template) {
 			ctx.ui.notify("Could not load SF preferences template.", "error");
diff --git a/src/resources/extensions/sf/deep-project-setup-policy.js b/src/resources/extensions/sf/deep-project-setup-policy.js
index b7f38e70a..6b45955c1 100644
--- a/src/resources/extensions/sf/deep-project-setup-policy.js
+++ b/src/resources/extensions/sf/deep-project-setup-policy.js
@@ -18,17 +18,29 @@ export function researchDecisionPath(basePath) {
 	return join(runtimeDir(basePath), "research-decision.json");
 }
 export function isWorkflowPrefsCaptured(basePath) {
-	const prefsPath = join(sfRoot(basePath), "PREFERENCES.md");
-	if (!existsSync(prefsPath)) return false;
-	let content;
-	try {
-		content = readFileSync(prefsPath, "utf-8");
-	} catch {
-		return false;
+	// Check yaml (canonical) first, fallback to legacy md
+	const sfRootPath = sfRoot(basePath);
+	const candidates = [
+		join(sfRootPath, "preferences.yaml"),
+		join(sfRootPath, "PREFERENCES.md"),
+		join(sfRootPath, "preferences.md"),
+	];
+	for (const prefsPath of candidates) {
+		if (!existsSync(prefsPath)) continue;
+		let content;
+		try {
+			content = readFileSync(prefsPath, "utf-8");
+		} catch {
+			return false;
+		}
+		if (prefsPath.endsWith(".yaml")) {
+			return /^workflow_prefs_captured:\s*true\s*$/m.test(content);
+		}
+		const match = content.match(/^---\r?\n([\s\S]*?)\r?\n---/);
+		if (!match) return false;
+		return /^workflow_prefs_captured:\s*true\s*$/m.test(match[1]);
 	}
-	const match = content.match(/^---\r?\n([\s\S]*?)\r?\n---/);
-	if (!match) return false;
-	return /^workflow_prefs_captured:\s*true\s*$/m.test(match[1]);
+	return false;
 }
 export function writeDefaultResearchSkipDecision(
 	basePath,
@@ -88,7 +100,7 @@ export function resolveDeepProjectSetupState(prefs, basePath) {
 		return {
 			status: "pending",
 			stage: "workflow-preferences",
-			reason: ".sf/PREFERENCES.md is missing workflow_prefs_captured: true.",
+			reason: ".sf/preferences.yaml is missing workflow_prefs_captured: true.",
 		};
 	}
 	const projectPath = join(root, "PROJECT.md");
diff --git a/src/resources/extensions/sf/detection.js b/src/resources/extensions/sf/detection.js
index 4ae64e598..3ba74ef40 100644
--- a/src/resources/extensions/sf/detection.js
+++ b/src/resources/extensions/sf/detection.js
@@ -311,6 +311,7 @@ function detectV2Sf(basePath) {
 	const sfPath = sfRoot(basePath);
 	if (!existsSync(sfPath)) return null;
 	const hasPreferences =
+		existsSync(join(sfPath, "preferences.yaml")) ||
 		existsSync(join(sfPath, "PREFERENCES.md")) ||
 		existsSync(join(sfPath, "preferences.md"));
 	const hasContext = existsSync(join(sfPath, "CONTEXT.md"));
@@ -862,6 +863,7 @@ function isMakeTestTargetSafe(basePath) {
  */
 export function hasGlobalSetup() {
 	return (
+		existsSync(join(sfHome, "preferences.yaml")) ||
 		existsSync(join(sfHome, "PREFERENCES.md")) ||
 		existsSync(join(sfHome, "preferences.md"))
 	);
@@ -874,6 +876,7 @@ export function isFirstEverLaunch() {
 	if (!existsSync(sfHome)) return true;
 	// If we have preferences, not first launch
 	if (
+		existsSync(join(sfHome, "preferences.yaml")) ||
 		existsSync(join(sfHome, "PREFERENCES.md")) ||
 		existsSync(join(sfHome, "preferences.md"))
 	) {
diff --git a/src/resources/extensions/sf/docs/preferences-reference.md b/src/resources/extensions/sf/docs/preferences-reference.md
index 1beb3dc73..40d7b871a 100644
--- a/src/resources/extensions/sf/docs/preferences-reference.md
+++ b/src/resources/extensions/sf/docs/preferences-reference.md
@@ -1,6 +1,6 @@
 # SF Preferences Reference
 
-Full documentation for `~/.sf/PREFERENCES.md` (global) and `.sf/PREFERENCES.md` (project).
+Full documentation for `~/.sf/preferences.yaml` (global) and `.sf/preferences.yaml` (project).
 
 ---
 
diff --git a/src/resources/extensions/sf/doctor-config-checks.js b/src/resources/extensions/sf/doctor-config-checks.js
index 12b69300a..6cbc6e1a4 100644
--- a/src/resources/extensions/sf/doctor-config-checks.js
+++ b/src/resources/extensions/sf/doctor-config-checks.js
@@ -45,7 +45,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `context_compact_at (${compactAt}) must be <= context_hard_limit (${hardLimit}). Otherwise context compaction happens too late.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: true,
 			});
 			if (shouldFix("config_context_compact_exceeds_hard_limit")) {
@@ -64,7 +64,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `context_hard_limit (${hardLimit}) is very low. Typical prompts + context are 10-15k tokens. Consider increasing to at least 25000.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -78,7 +78,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `unit_timeout (${unitTimeout}s) is very low. Most units take 2-5 minutes. Consider increasing to at least 180 seconds.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -106,7 +106,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 						scope: "project",
 						unitId: "config",
 						message: `unit_timeout_by_phase contains unrecognized phase "${phase}". Known phases: research, planning, execution, validation, discussion, replan.`,
-						file: ".sf/preferences.md or ~/.sf/preferences.md",
+						file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 						fixable: false,
 					});
 				}
@@ -117,7 +117,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 						scope: "project",
 						unitId: "config",
 						message: `unit_timeout_by_phase.${phase} (${timeout}s) is very low. Consider at least 180 seconds.`,
-						file: ".sf/preferences.md or ~/.sf/preferences.md",
+						file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 						fixable: false,
 					});
 				}
@@ -145,7 +145,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 						scope: "project",
 						unitId: "config",
 						message: `max_agents_by_phase contains unrecognized phase "${phase}". Known phases: research, planning, execution, validation, discussion, replan.`,
-						file: ".sf/preferences.md or ~/.sf/preferences.md",
+						file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 						fixable: false,
 					});
 				}
@@ -156,7 +156,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 						scope: "project",
 						unitId: "config",
 						message: `max_agents_by_phase.${phase} (${count}) is outside practical range [1, 16]. Most deployments use 1-4.`,
-						file: ".sf/preferences.md or ~/.sf/preferences.md",
+						file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 						fixable: false,
 					});
 				}
@@ -172,7 +172,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `worktree_mode "${worktreeMode}" is invalid. Must be one of: none, auto, manual.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -186,7 +186,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `tool_abort_grace (${toolAbortGrace}ms) cannot be negative.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: true,
 			});
 			if (shouldFix("config_tool_abort_grace_negative")) {
@@ -203,7 +203,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `max_turns_per_attempt (${maxTurns}) is very low. Most units need 10-50 turns. Increasing to at least 20 is recommended.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -214,7 +214,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `max_turns_per_attempt (${maxTurns}) is very high. Units reaching >100 turns are likely stuck. Consider investigating or lowering to 100.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -228,7 +228,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `hot_cache_turns (${hotCacheTurns}) cannot be negative.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: true,
 			});
 			if (shouldFix("config_hot_cache_negative")) {
@@ -242,7 +242,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 				scope: "project",
 				unitId: "config",
 				message: `hot_cache_turns (${hotCacheTurns}) is very high. Keeping >20 turns in memory wastes RAM. Consider 5-10.`,
-				file: ".sf/preferences.md or ~/.sf/preferences.md",
+				file: ".sf/preferences.yaml or ~/.sf/preferences.yaml",
 				fixable: false,
 			});
 		}
@@ -254,7 +254,7 @@ export async function checkConfigHealth(issues, fixesApplied, shouldFix) {
 			scope: "project",
 			unitId: "config",
 			message: `Config health check failed: ${err instanceof Error ? err.message : String(err)}`,
-			file: ".sf/preferences.md",
+			file: ".sf/preferences.yaml",
 			fixable: false,
 		});
 	}
@@ -307,7 +307,7 @@ export function checkVaultHealth(issues, _shouldFix) {
 				scope: "project",
 				unitId: "vault",
 				message: `Vault URIs detected (${vaultUris.length}) but no credentials found. Set VAULT_TOKEN or create ~/.vault-token to use vault.`,
-				file: ".sf/preferences.md or environment",
+				file: ".sf/preferences.yaml or environment",
 				fixable: false,
 			});
 			return;
@@ -373,7 +373,7 @@ export function checkVaultHealth(issues, _shouldFix) {
 			scope: "project",
 			unitId: "vault",
 			message: `Vault health check failed: ${err instanceof Error ? err.message : String(err)}`,
-			file: ".sf/preferences.md",
+			file: ".sf/preferences.yaml",
 			fixable: false,
 		});
 	}
diff --git a/src/resources/extensions/sf/doctor-providers.js b/src/resources/extensions/sf/doctor-providers.js
index a8d1cf682..3cfabba12 100644
--- a/src/resources/extensions/sf/doctor-providers.js
+++ b/src/resources/extensions/sf/doctor-providers.js
@@ -14,11 +14,8 @@ import { existsSync } from "node:fs";
 import { AuthStorage } from "@singularity-forge/coding-agent";
 import { getAuthPath, PROVIDER_REGISTRY } from "./key-manager.js";
 import { loadEffectiveSFPreferences } from "./preferences.js";
-import { getConfiguredEnvApiKey } from "./provider-env-auth.js";
-import {
-	couldBeVaultUri,
-	hasProviderCredentialEnvVar,
-} from "./vault-credential-resolver.js";
+import { getConfiguredEnvApiKey, getGatedEnvVarKey } from "./provider-env-auth.js";
+import { couldBeVaultUri } from "./vault-credential-resolver.js";
 
 // ── Model → Provider ID mapping ───────────────────────────────────────────────
 /**
@@ -149,9 +146,9 @@ function resolveKey(providerId) {
 	if (info?.envVar && couldBeVaultUri(process.env[info.envVar])) {
 		return { found: true, source: "vault", backedOff: false };
 	}
-	// Fall back to PROVIDER_REGISTRY env var for providers not covered by getEnvApiKey
-	// (e.g., search providers like Brave, Tavily; tool providers like Jina, Context7)
-	if (info?.envVar && hasProviderCredentialEnvVar(info.envVar)) {
+	// Fallback for providers not covered by getEnvApiKey (search/tool providers like
+	// Brave, Tavily, Jina, Context7) — still gated by providerEnvAuth setting.
+	if (info?.envVar && getGatedEnvVarKey(providerId, info.envVar)) {
 		return { found: true, source: "env", backedOff: false };
 	}
 	return { found: false, source: "none", backedOff: false };
@@ -339,7 +336,7 @@ function checkOptionalProviders() {
 	// "not configured" noise for alternative search providers when at least
 	// one is already active (e.g. don't warn about missing BRAVE_API_KEY
 	// when Tavily is configured).
-	const searchProviderIds = ["brave", "tavily"];
+	const searchProviderIds = PROVIDER_REGISTRY.filter((p) => p.category === "search").map((p) => p.id);
 	const hasAnySearchProvider = searchProviderIds.some(
 		(id) => resolveKey(id).found,
 	);
diff --git a/src/resources/extensions/sf/gitignore.js b/src/resources/extensions/sf/gitignore.js
index 8fcfb0b01..c1697e1eb 100644
--- a/src/resources/extensions/sf/gitignore.js
+++ b/src/resources/extensions/sf/gitignore.js
@@ -1,8 +1,8 @@
 /**
- * SF bootstrappers for .gitignore and PREFERENCES.md
+ * SF bootstrappers for .gitignore and preferences.yaml
  *
  * Ensures baseline .gitignore exists with universally-correct patterns.
- * Creates an empty PREFERENCES.md template if it doesn't exist.
+ * Creates an empty preferences.yaml template if it doesn't exist.
  * Both idempotent — non-destructive if already present.
  */
 import { execFileSync } from "node:child_process";
@@ -14,7 +14,6 @@ import { GIT_NO_PROMPT_ENV } from "./git-constants.js";
 import { SF_RUNTIME_PATTERNS } from "./git-runtime-patterns.js";
 import { nativeLsFiles, nativeRmCached } from "./native-git-bridge.js";
 import { sfRoot } from "./paths.js";
-import { bodyHash as preferencesBodyHash } from "./scaffold-versioning.js";
 
 export { SF_RUNTIME_PATTERNS } from "./git-runtime-patterns.js";
 
@@ -291,23 +290,20 @@ export function untrackRuntimeFiles(basePath) {
 	}
 }
 /**
- * Ensure basePath/.sf/PREFERENCES.md exists as an empty template.
- * Creates the file with frontmatter only if it doesn't exist.
+ * Ensure basePath/.sf/preferences.yaml exists as a template.
+ * Creates the file with YAML only if it doesn't exist.
  * Returns true if created, false if already exists.
  *
- * Checks both uppercase (canonical) and lowercase (legacy) to avoid
- * creating a duplicate when a lowercase file already exists.
+ * Checks yaml (canonical) and legacy .md variants to avoid duplicates.
  */
 export function ensurePreferences(basePath) {
-	const preferencesPath = join(sfRoot(basePath), "PREFERENCES.md");
+	const yamlPath = join(sfRoot(basePath), "preferences.yaml");
+	const uppercasePath = join(sfRoot(basePath), "PREFERENCES.md");
 	const legacyPath = join(sfRoot(basePath), "preferences.md");
-	if (existsSync(preferencesPath) || existsSync(legacyPath)) {
+	if (existsSync(yamlPath) || existsSync(uppercasePath) || existsSync(legacyPath)) {
 		return false;
 	}
-	// Auto-detect project type and seed verification_commands. Without this,
-	// projects fall back to the user-level defaults — which point at sf's own
-	// dev scripts (npm run typecheck:extensions, test:sf-light) and produce
-	// false negatives on every non-Node project. Detection failure is non-fatal.
+	// Auto-detect project type and seed verification_commands.
 	let verifySection = "";
 	try {
 		const signals = detectProjectSignals(basePath);
@@ -320,23 +316,11 @@ export function ensurePreferences(basePath) {
 	} catch {
 		// fall through to bare template
 	}
-	// Stamp the sf version that wrote this template. Drift detection in
-	// checkPreferencesDrift uses this to flag stale templates after major
-	// sf updates. SF_VERSION is set by loader.ts; fall back to "0.0.0" if
-	// the env var is missing (atypical entry point).
 	const sfVersion = process.env.SF_VERSION || "0.0.0";
-	// ADR-021 Phase A: record initial template state + body hash in the
-	// frontmatter alongside last_synced_with_sf. The hash covers the
-	// Markdown body (everything after the closing `---` of frontmatter)
-	// so the same drift-detection pattern works as for marker-stamped
-	// Markdown docs.
-	const prefBody = `\n# SF Skill Preferences\n\nProject-specific guidance for skill selection and execution preferences.\n\nSee \`~/.sf/agent/extensions/sf/docs/preferences-reference.md\` for full field documentation and examples.\n\n## Fields\n\n- \`always_use_skills\`: Skills that must be available during all SF operations\n- \`prefer_skills\`: Skills to prioritize when multiple options exist\n- \`avoid_skills\`: Skills to minimize or avoid (with lower priority than prefer)\n- \`skill_rules\`: Context-specific rules (e.g., "use tool X for Y type of work")\n- \`custom_instructions\`: Append-only project guidance (do not override system rules)\n- \`models\`: Model preferences for specific task types\n- \`skill_discovery\`: Automatic skill detection preferences\n- \`auto_supervisor\`: Supervision and gating rules for autonomous modes\n- \`git\`: Git preferences — \`main_branch\` (default branch name for new repos, e.g., "main", "master", "trunk"), \`auto_push\`, \`snapshots\`, etc.\n\n## Examples\n\n\`\`\`yaml\nprefer_skills:\n  - playwright\n  - resolve_library\navoid_skills:\n  - subagent  # prefer direct execution in this project\n\ncustom_instructions:\n  - "Always verify with browser_assert before marking UI work done"\n  - "Use Context7 for all library/framework decisions"\n\`\`\`\n`;
-	const prefBodyHash = preferencesBodyHash(prefBody);
-	const template = `---
+	const template = `# SF preferences — see ~/.sf/agent/extensions/sf/docs/preferences-reference.md for docs
 version: 1
 last_synced_with_sf: ${yamlSafeString(sfVersion)}
 sf_template_state: pending
-sf_template_hash: ${yamlSafeString(prefBodyHash)}
 ${verifySection}always_use_skills: []
 prefer_skills: []
 avoid_skills: []
@@ -345,40 +329,7 @@ custom_instructions: []
 models: {}
 skill_discovery: {}
 auto_supervisor: {}
----
-
-# SF Skill Preferences
-
-Project-specific guidance for skill selection and execution preferences.
-
-See \`~/.sf/agent/extensions/sf/docs/preferences-reference.md\` for full field documentation and examples.
-
-## Fields
-
-- \`always_use_skills\`: Skills that must be available during all SF operations
-- \`prefer_skills\`: Skills to prioritize when multiple options exist
-- \`avoid_skills\`: Skills to minimize or avoid (with lower priority than prefer)
-- \`skill_rules\`: Context-specific rules (e.g., "use tool X for Y type of work")
-- \`custom_instructions\`: Append-only project guidance (do not override system rules)
-- \`models\`: Model preferences for specific task types
-- \`skill_discovery\`: Automatic skill detection preferences
-- \`auto_supervisor\`: Supervision and gating rules for autonomous modes
-- \`git\`: Git preferences — \`main_branch\` (default branch name for new repos, e.g., "main", "master", "trunk"), \`auto_push\`, \`snapshots\`, etc.
-
-## Examples
-
-\`\`\`yaml
-prefer_skills:
-  - playwright
-  - resolve_library
-avoid_skills:
-  - subagent  # prefer direct execution in this project
-
-custom_instructions:
-  - "Always verify with browser_assert before marking UI work done"
-  - "Use Context7 for all library/framework decisions"
-\`\`\`
 `;
-	writeFileSync(preferencesPath, template, "utf-8");
+	writeFileSync(yamlPath, template, "utf-8");
 	return true;
 }
diff --git a/src/resources/extensions/sf/guided-flow.js b/src/resources/extensions/sf/guided-flow.js
index dbf5512a4..3710b1371 100644
--- a/src/resources/extensions/sf/guided-flow.js
+++ b/src/resources/extensions/sf/guided-flow.js
@@ -1594,12 +1594,13 @@ export async function showWorkflowEntry(ctx, pi, basePath, options) {
 	}
 	// ── Detection preamble — run before any bootstrap ────────────────────
 	// Check bootstrap completeness, not just .sf/ directory existence.
-	// A zombie .sf/ state (symlink exists but missing PREFERENCES.md and
+	// A zombie .sf/ state (symlink exists but missing preferences.yaml/PREFERENCES.md and
 	// milestones/) must trigger the init wizard, not skip it (#2942).
 	const sfPath = sfRoot(basePath);
 	const hasBootstrapArtifacts =
 		existsSync(sfPath) &&
-		(existsSync(join(sfPath, "PREFERENCES.md")) ||
+		(existsSync(join(sfPath, "preferences.yaml")) ||
+			existsSync(join(sfPath, "PREFERENCES.md")) ||
 			existsSync(join(sfPath, "milestones")));
 	if (!hasBootstrapArtifacts) {
 		const detection = detectProjectState(basePath);
diff --git a/src/resources/extensions/sf/init-wizard.js b/src/resources/extensions/sf/init-wizard.js
index f68d74d14..301966e4e 100644
--- a/src/resources/extensions/sf/init-wizard.js
+++ b/src/resources/extensions/sf/init-wizard.js
@@ -507,9 +507,9 @@ function bootstrapSfDirectory(basePath, prefs, signals) {
 	const sf = sfRoot(basePath);
 	mkdirSync(join(sf, "milestones"), { recursive: true });
 	mkdirSync(join(sf, "runtime"), { recursive: true });
-	// Write PREFERENCES.md from wizard answers
+	// Write preferences.yaml from wizard answers (pure YAML, no frontmatter markers)
 	const preferencesContent = buildPreferencesFile(prefs);
-	writeFileSync(join(sf, "PREFERENCES.md"), preferencesContent, "utf-8");
+	writeFileSync(join(sf, "preferences.yaml"), preferencesContent, "utf-8");
 	// Seed CONTEXT.md with detected project signals
 	const contextContent = buildContextSeed(signals);
 	if (contextContent) {
@@ -519,7 +519,7 @@ function bootstrapSfDirectory(basePath, prefs, signals) {
 	ensureSiftIndexWarmup(basePath);
 }
 function buildPreferencesFile(prefs) {
-	const lines = ["---"];
+	const lines = ["# SF preferences — see ~/.sf/agent/extensions/sf/docs/preferences-reference.md for docs"];
 	lines.push("version: 1");
 	lines.push(`mode: ${prefs.mode}`);
 	// Git preferences
@@ -559,17 +559,6 @@ function buildPreferencesFile(prefs) {
 	if (prefs.minRequestIntervalMs > 0) {
 		lines.push(`min_request_interval_ms: ${prefs.minRequestIntervalMs}`);
 	}
-	lines.push("---");
-	lines.push("");
-	lines.push("# SF Project Preferences");
-	lines.push("");
-	lines.push(
-		"Generated by `/init`. Edit directly or use `/prefs project` to modify.",
-	);
-	lines.push("");
-	lines.push(
-		"See `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full field documentation.",
-	);
 	lines.push("");
 	return lines.join("\n");
 }
diff --git a/src/resources/extensions/sf/key-manager.js b/src/resources/extensions/sf/key-manager.js
index 2f8388b8d..e0884ee70 100644
--- a/src/resources/extensions/sf/key-manager.js
+++ b/src/resources/extensions/sf/key-manager.js
@@ -8,6 +8,7 @@ import { chmodSync, existsSync, mkdirSync, statSync } from "node:fs";
 import { dirname, join } from "node:path";
 import { AuthStorage } from "@singularity-forge/coding-agent";
 import { getErrorMessage } from "./error-utils.js";
+import { isEnvAuthAllowed } from "./provider-env-auth.js";
 export const PROVIDER_REGISTRY = [
 	// LLM Providers
 	{
@@ -291,7 +292,7 @@ export function getAllKeyStatuses(auth) {
 		const rawCreds = auth.getCredentialsForProvider(provider.id);
 		// Filter out empty-key entries (left by legacy removeProviderToken or skipped onboarding)
 		const creds = rawCreds.filter((c) => !(c.type === "api_key" && !c.key));
-		const envKey = getProviderEnvKey(provider);
+		const envKey = isEnvAuthAllowed(provider.id) ? getProviderEnvKey(provider) : undefined;
 		if (creds.length > 0) {
 			const firstCred = creds[0];
 			const desc =
@@ -868,8 +869,9 @@ export function runKeyDoctor(auth) {
 			}
 		}
 	}
-	// 4. Check for env var conflicts
+	// 4. Check for env var conflicts (only when env auth is allowed for that provider)
 	for (const provider of PROVIDER_REGISTRY) {
+		if (!isEnvAuthAllowed(provider.id)) continue;
 		const envKey = getProviderEnvKey(provider);
 		if (!envKey) continue;
 		const creds = auth.getCredentialsForProvider(provider.id);
@@ -900,7 +902,7 @@ export function runKeyDoctor(auth) {
 		const hasValidKey = creds.some((c) =>
 			c.type === "api_key" ? !!c.key : true,
 		);
-		const hasEnv = !!getProviderEnvKey(p);
+		const hasEnv = isEnvAuthAllowed(p.id) && !!getProviderEnvKey(p);
 		return hasValidKey || hasEnv;
 	});
 	if (!hasAnyLlm) {
diff --git a/src/resources/extensions/sf/planning-depth.js b/src/resources/extensions/sf/planning-depth.js
index f423da377..df0451160 100644
--- a/src/resources/extensions/sf/planning-depth.js
+++ b/src/resources/extensions/sf/planning-depth.js
@@ -1,9 +1,9 @@
-// SF — Deep planning mode — Helper to set planning_depth in .sf/PREFERENCES.md.
+// SF — Deep planning mode — Helper to set planning_depth in .sf/preferences.yaml.
 //
 // Persists the user's deep-mode opt-in across sessions. Reads the existing
-// preferences file (if any), parses its YAML frontmatter, sets/updates
-// planning_depth, and writes the file back preserving body content and other
-// frontmatter keys.
+// preferences file (if any), parses its YAML, sets/updates planning_depth,
+// and writes the file back preserving body content (for legacy .md) or the full
+// YAML (for .yaml).
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
 import { dirname, join } from "node:path";
 import { parse as parseYaml, stringify as stringifyYaml } from "yaml";
@@ -12,10 +12,19 @@ import { logWarning } from "./workflow-logger.js";
 
 const FRONTMATTER_RE = /^---\r?\n([\s\S]*?)\r?\n---\r?\n?([\s\S]*)$/;
 /**
- * Resolve the path to the project-level .sf/PREFERENCES.md file.
+ * Resolve the path to the project-level preferences file (yaml canonical, md fallback).
+ * Returns { path, isYaml } where isYaml indicates the format to use for writes.
  */
 function getProjectSFPreferencesFilePath(basePath) {
-	return join(sfRoot(basePath), "PREFERENCES.md");
+	const sfRootPath = sfRoot(basePath);
+	const yamlPath = join(sfRootPath, "preferences.yaml");
+	if (existsSync(yamlPath)) return { path: yamlPath, isYaml: true };
+	const upperMdPath = join(sfRootPath, "PREFERENCES.md");
+	if (existsSync(upperMdPath)) return { path: upperMdPath, isYaml: false };
+	const lowerMdPath = join(sfRootPath, "preferences.md");
+	if (existsSync(lowerMdPath)) return { path: lowerMdPath, isYaml: false };
+	// Default to yaml for new files
+	return { path: yamlPath, isYaml: true };
 }
 /**
  * Resolve the path to the project-level .sf/runtime/research-decision.json file.
@@ -40,36 +49,51 @@ export function writeDefaultResearchSkipDecision(basePath) {
 	writeFileSync(decisionPath, payload, "utf-8");
 }
 /**
- * Set planning_depth in the project's .sf/PREFERENCES.md.
+ * Set planning_depth in the project's preferences file (.sf/preferences.yaml or legacy .sf/PREFERENCES.md).
  * Creates the file if it does not exist. Preserves existing frontmatter
  * keys and body content. Intended to be called when the user opts into
  * (or out of) deep mode via `/new-project --deep` or similar.
  */
 export function setPlanningDepth(basePath, depth) {
-	const path = getProjectSFPreferencesFilePath(basePath);
-	const { frontmatter, body } = readProjectPreferencesParts(path);
+	const { path, isYaml } = getProjectSFPreferencesFilePath(basePath);
+	const { frontmatter, body } = readProjectPreferencesParts(path, isYaml);
 	frontmatter.planning_depth = depth;
 	if (depth === "deep") {
 		applyDeepWorkflowPreferenceDefaults(frontmatter);
 	}
-	writeProjectPreferencesParts(path, frontmatter, body);
+	writeProjectPreferencesParts(path, frontmatter, body, isYaml);
 	if (depth === "deep") {
 		ensureResearchDecisionDefault(basePath);
 	}
 }
 export function ensureWorkflowPreferencesCaptured(basePath) {
-	const path = getProjectSFPreferencesFilePath(basePath);
-	const { frontmatter, body } = readProjectPreferencesParts(path);
+	const { path, isYaml } = getProjectSFPreferencesFilePath(basePath);
+	const { frontmatter, body } = readProjectPreferencesParts(path, isYaml);
 	frontmatter.planning_depth = "deep";
 	applyDeepWorkflowPreferenceDefaults(frontmatter);
-	writeProjectPreferencesParts(path, frontmatter, body);
+	writeProjectPreferencesParts(path, frontmatter, body, isYaml);
 	ensureResearchDecisionDefault(basePath);
 }
-function readProjectPreferencesParts(path) {
+function readProjectPreferencesParts(path, isYaml) {
 	let frontmatter = {};
 	let body = "";
 	if (existsSync(path)) {
 		const content = readFileSync(path, "utf-8");
+		if (isYaml) {
+			// Pure YAML — no frontmatter markers
+			try {
+				const parsed = parseYaml(content);
+				if (parsed && typeof parsed === "object" && !Array.isArray(parsed)) {
+					frontmatter = parsed;
+				}
+			} catch (err) {
+				logWarning(
+					"guided",
+					`preferences.yaml has invalid YAML — rewriting: ${err instanceof Error ? err.message : String(err)}`,
+				);
+			}
+			return { frontmatter, body: "" };
+		}
 		const match = content.match(FRONTMATTER_RE);
 		if (match) {
 			try {
@@ -79,28 +103,28 @@ function readProjectPreferencesParts(path) {
 				}
 				body = match[2];
 			} catch (err) {
-				// Invalid YAML — don't lose user content. Treat the whole file as
-				// a legacy non-frontmatter document and preserve it via the body
-				// path. The depth setter then prepends a fresh frontmatter block.
 				logWarning(
 					"guided",
-					`PREFERENCES.md frontmatter has invalid YAML — preserving body and rewriting frontmatter: ${err instanceof Error ? err.message : String(err)}`,
+					`preferences file frontmatter has invalid YAML — preserving body and rewriting frontmatter: ${err instanceof Error ? err.message : String(err)}`,
 				);
 				body = content;
 			}
 		} else {
-			// No frontmatter delimiters — preserve existing content as body.
 			body = content;
 		}
 	}
 	return { frontmatter, body };
 }
-function writeProjectPreferencesParts(path, frontmatter, body) {
-	// yaml.stringify emits a trailing newline. Strip if present so we control framing.
+function writeProjectPreferencesParts(path, frontmatter, body, isYaml) {
 	const yamlBlock = stringifyYaml(frontmatter).replace(/\n$/, "");
-	const newContent = body
-		? `---\n${yamlBlock}\n---\n\n${body.replace(/^\n+/, "")}`
-		: `---\n${yamlBlock}\n---\n`;
+	let newContent;
+	if (isYaml) {
+		newContent = `${yamlBlock}\n`;
+	} else {
+		newContent = body
+			? `---\n${yamlBlock}\n---\n\n${body.replace(/^\n+/, "")}`
+			: `---\n${yamlBlock}\n---\n`;
+	}
 	mkdirSync(dirname(path), { recursive: true });
 	writeFileSync(path, newContent, "utf-8");
 }
diff --git a/src/resources/extensions/sf/preferences-models.js b/src/resources/extensions/sf/preferences-models.js
index 6d02cdb4e..77a9c4ecc 100644
--- a/src/resources/extensions/sf/preferences-models.js
+++ b/src/resources/extensions/sf/preferences-models.js
@@ -38,7 +38,7 @@ function getGlobalSFPreferencesPath() {
 	return _getGlobalSFPreferencesPath();
 }
 
-import { getConfiguredEnvApiKey } from "./provider-env-auth.js";
+import { getKeyManagerAuthStorage } from "./key-manager.js";
 
 const OPENCODE_FREE_MODEL_IDS = new Set([
 	"big-pickle",
@@ -275,10 +275,18 @@ function resolveAutoBenchmarkPickForUnit(unitType, prefs) {
 	try {
 		const allowed = prefs?.allowed_providers?.map((s) => s.toLowerCase());
 		const blocked = prefs?.blocked_providers?.map((s) => s.toLowerCase());
+		const auth = getKeyManagerAuthStorage();
+		const configuredProviderIds = new Set(
+			auth.getConfiguredProviders?.() ??
+			getProviders().filter((p) => {
+				const creds = auth.getCredentialsForProvider(p);
+				return creds.some((c) => c.type === "oauth" || (c.type === "api_key" && c.key));
+			}),
+		);
 		const candidates = [];
 		for (const provider of getProviders()) {
 			if (!isProviderAllowedByLists(provider, allowed, blocked)) continue;
-			if (!getConfiguredEnvApiKey(provider)) continue;
+			if (!configuredProviderIds.has(provider)) continue;
 			for (const model of getModels(provider)) {
 				if (
 					!isProviderModelAllowed(
@@ -440,7 +448,7 @@ export function resolveModelWithFallbacksForUnit(unitType, options = {}) {
  *
  * Used at autonomous mode bootstrap to override the session model that was
  * determined by settings.json (defaultProvider/defaultModel).  When
- * PREFERENCES.md (or project preferences) configures an `execution` model
+ * preferences.yaml (or project preferences) configures an `execution` model
  * we treat that as the session default.  Falls back through execution →
  * planning → first configured model.
  *
@@ -509,11 +517,11 @@ export function resolveDefaultSessionModel(sessionProvider) {
  * proxies, etc.).
  *
  * Used by autonomous mode bootstrap to decide whether the session model
- * (set via `/model`) should override `PREFERENCES.md`.  Custom providers
- * are never reachable from `PREFERENCES.md` (which only knows built-in
+ * (set via `/model`) should override `preferences.yaml`.  Custom providers
+ * are never reachable from `preferences.yaml` (which only knows built-in
  * providers), so when the user has explicitly selected one, it must take
  * priority — otherwise autonomous mode tries to start the built-in provider from
- * PREFERENCES.md and fails with "Not logged in · Please run /login" (#4122).
+ * preferences.yaml and fails with "Not logged in · Please run /login" (#4122).
  *
  * Reads models.json directly with a lightweight JSON parse to avoid
  * pulling in the full model-registry at this call site.  Falls back to
@@ -848,3 +856,23 @@ export function resolveSearchProviderFromPreferences() {
 	const prefs = loadEffectiveSFPreferences();
 	return prefs?.preferences.search_provider;
 }
+
+// Word-boundary patterns for known heavy/expensive model families.
+// "Heavy" means: high cost, high latency — blocked when modelMode === "fast".
+// Use word boundaries (\b) so "opus-lite" or "mini-o1" don't false-positive.
+const HEAVY_MODEL_PATTERNS = [
+	/\bopus\b/i,
+	/\bo1\b/i,
+	/\bo3\b/i,
+	/\bgpt-4-turbo\b/i,
+	/\bgpt-5\b/i,
+	/\bdeepseek-reasoner\b/i,
+];
+/**
+ * Returns true if modelId belongs to a known heavy (high-cost/high-latency) family.
+ * Used to enforce `modelMode === "fast"` constraints on subagent dispatch.
+ */
+export function isHeavyModelId(modelId) {
+	if (!modelId || typeof modelId !== "string") return false;
+	return HEAVY_MODEL_PATTERNS.some((pattern) => pattern.test(modelId));
+}
diff --git a/src/resources/extensions/sf/preferences-serializer.js b/src/resources/extensions/sf/preferences-serializer.js
index 3f2e28273..b4a11c1a6 100644
--- a/src/resources/extensions/sf/preferences-serializer.js
+++ b/src/resources/extensions/sf/preferences-serializer.js
@@ -36,7 +36,7 @@ export function yamlSafeString(val) {
  * stable diffs; unknown keys are appended after the ordered set.
  *
  * Purpose: produce the YAML block written between `---` markers in
- * PREFERENCES.md.  Relies only on yamlSafeString — no filesystem or
+ * preferences.yaml (or legacy PREFERENCES.md).  Relies only on yamlSafeString — no filesystem or
  * preferences-loading imports needed.
  *
  * Consumer: preferences-template-upgrade.js, commands-prefs-wizard.js.
diff --git a/src/resources/extensions/sf/preferences-template-upgrade.js b/src/resources/extensions/sf/preferences-template-upgrade.js
index 05e3551b6..9faa5ff6b 100644
--- a/src/resources/extensions/sf/preferences-template-upgrade.js
+++ b/src/resources/extensions/sf/preferences-template-upgrade.js
@@ -55,6 +55,15 @@ export function upgradePreferencesFileIfDrifted(path, prefs) {
 	} catch {
 		return upgraded;
 	}
+	// Pure YAML file — rewrite entirely (no frontmatter markers, no body to preserve)
+	if (path.endsWith(".yaml")) {
+		try {
+			writeFileSync(path, serializePreferencesToFrontmatter(upgraded), "utf-8");
+		} catch {
+			// Read-only filesystem, permission error, etc. — not fatal.
+		}
+		return upgraded;
+	}
 	const startMarker = content.startsWith("---\r\n") ? "---\r\n" : "---\n";
 	if (!content.startsWith(startMarker)) {
 		// File doesn't have the canonical frontmatter shape — leave it alone.
diff --git a/src/resources/extensions/sf/preferences-validation.js b/src/resources/extensions/sf/preferences-validation.js
index 9082f571d..b1f05a256 100644
--- a/src/resources/extensions/sf/preferences-validation.js
+++ b/src/resources/extensions/sf/preferences-validation.js
@@ -17,6 +17,7 @@ import {
 	KNOWN_UNIT_TYPES,
 	SKILL_ACTIONS,
 } from "./preferences-types.js";
+import { VALID_SEARCH_PROVIDER_PREFS } from "./setup-catalog.js";
 
 const VALID_TOKEN_PROFILES = new Set([
 	"budget",
@@ -420,25 +421,14 @@ export function validatePreferences(preferences) {
 	}
 	// ─── Search Provider ─────────────────────────────────────────────
 	if (preferences.search_provider !== undefined) {
-		const validSearchProviders = new Set([
-			"brave",
-			"tavily",
-			"minimax",
-			"serper",
-			"exa",
-			"ollama",
-			"combosearch",
-			"native",
-			"auto",
-		]);
 		if (
 			typeof preferences.search_provider === "string" &&
-			validSearchProviders.has(preferences.search_provider)
+			VALID_SEARCH_PROVIDER_PREFS.has(preferences.search_provider)
 		) {
 			validated.search_provider = preferences.search_provider;
 		} else {
 			errors.push(
-				`search_provider must be one of: brave, tavily, minimax, serper, exa, ollama, combosearch, native, auto`,
+				`search_provider must be one of: ${[...VALID_SEARCH_PROVIDER_PREFS].join(", ")}`,
 			);
 		}
 	}
diff --git a/src/resources/extensions/sf/preferences.js b/src/resources/extensions/sf/preferences.js
index 155d719e8..e1703c810 100644
--- a/src/resources/extensions/sf/preferences.js
+++ b/src/resources/extensions/sf/preferences.js
@@ -78,16 +78,24 @@ export {
 function sfHome() {
 	return process.env.SF_HOME || join(homedir(), ".sf");
 }
+// Canonical new location — pure YAML, no frontmatter markers
+function globalPreferencesYamlPath() {
+	return join(sfHome(), "preferences.yaml");
+}
+// Legacy markdown paths kept for fallback reads
 function globalPreferencesPath() {
 	return join(sfHome(), "preferences.md");
 }
+function globalPreferencesPathUppercase() {
+	return join(sfHome(), "PREFERENCES.md");
+}
 function legacyGlobalPreferencesPath() {
 	return join(homedir(), ".pi", "agent", "sf-preferences.md");
 }
 /**
  * Resolve the "project root" for preferences. When SF is running inside a
  * git worktree (e.g. `.sf/worktrees/M003/`), project-level prefs should
- * come from the MAIN worktree's `.sf/PREFERENCES.md`, not the milestone
+ * come from the MAIN worktree's `.sf/preferences.yaml`, not the milestone
  * branch's frozen copy. Otherwise a pref change on main never reaches an
  * in-flight milestone, and we saw this in practice: updating PREFERENCES
  * on main had no effect until the milestone branch merged main.
@@ -123,22 +131,23 @@ function projectPrefsRoot() {
 	}
 	return cwd;
 }
+// Canonical new location — pure YAML
+function projectPreferencesYamlPath() {
+	return join(sfRoot(projectPrefsRoot()), "preferences.yaml");
+}
+// Legacy markdown paths kept for fallback reads
 function projectPreferencesPath() {
 	return join(sfRoot(projectPrefsRoot()), "preferences.md");
 }
-// Bootstrap in gitignore.ts historically created PREFERENCES.md (uppercase) by mistake.
-// Check uppercase as a fallback so those files aren't silently ignored.
-function globalPreferencesPathUppercase() {
-	return join(sfHome(), "PREFERENCES.md");
-}
 function projectPreferencesPathUppercase() {
 	return join(sfRoot(projectPrefsRoot()), "PREFERENCES.md");
 }
 /**
- * Get the path to the global SF preferences file.
+ * Get the canonical path for the global SF preferences file.
+ * New installs use preferences.yaml; legacy .md files are read as fallbacks.
  */
 export function getGlobalSFPreferencesPath() {
-	return globalPreferencesPath();
+	return globalPreferencesYamlPath();
 }
 /**
  * Get the path to the legacy global SF preferences file (deprecated location).
@@ -147,27 +156,30 @@ export function getLegacyGlobalSFPreferencesPath() {
 	return legacyGlobalPreferencesPath();
 }
 /**
- * Get the path to the project-level SF preferences file.
+ * Get the canonical path for the project-level SF preferences file.
+ * New installs use preferences.yaml; legacy .md files are read as fallbacks.
  */
 export function getProjectSFPreferencesPath() {
-	return projectPreferencesPath();
+	return projectPreferencesYamlPath();
 }
 // ─── Loading ────────────────────────────────────────────────────────────────
 /**
- * Load global SF preferences, trying multiple paths and legacy locations.
+ * Load global SF preferences, trying yaml first then legacy markdown locations.
  */
 export function loadGlobalSFPreferences() {
 	return (
+		loadPreferencesFile(globalPreferencesYamlPath(), "global") ??
 		loadPreferencesFile(globalPreferencesPath(), "global") ??
 		loadPreferencesFile(globalPreferencesPathUppercase(), "global") ??
 		loadPreferencesFile(legacyGlobalPreferencesPath(), "global")
 	);
 }
 /**
- * Load project-level SF preferences.
+ * Load project-level SF preferences, trying yaml first then legacy markdown.
  */
 export function loadProjectSFPreferences() {
 	return (
+		loadPreferencesFile(projectPreferencesYamlPath(), "project") ??
 		loadPreferencesFile(projectPreferencesPath(), "project") ??
 		loadPreferencesFile(projectPreferencesPathUppercase(), "project")
 	);
@@ -225,7 +237,10 @@ export function loadEffectiveSFPreferences() {
 function loadPreferencesFile(path, scope) {
 	if (!existsSync(path)) return null;
 	const raw = readFileSync(path, "utf-8");
-	const preferences = parsePreferencesMarkdown(raw);
+	// .yaml files are pure YAML — no frontmatter extraction needed
+	const preferences = path.endsWith(".yaml")
+		? parsePreferencesYaml(raw)
+		: parsePreferencesMarkdown(raw);
 	if (!preferences) return null;
 	const validation = validatePreferences(preferences);
 	// Self-align: if the file's recorded sf version drifted from current,
@@ -249,6 +264,22 @@ export function _resetParseWarningFlag() {
 	_warnedFrontmatterParse = false;
 	_warnedSectionParse = false;
 }
+/**
+ * Parse preferences from a pure YAML file (no frontmatter markers needed).
+ * Used for preferences.yaml; the entire file content is YAML.
+ *
+ * @internal Exported for testing only
+ */
+export function parsePreferencesYaml(content) {
+	try {
+		const parsed = parseYaml(content);
+		if (typeof parsed !== "object" || parsed === null) return {};
+		return parsed;
+	} catch (e) {
+		logWarning("guided", `YAML parse error in preferences.yaml: ${e.message}`);
+		return {};
+	}
+}
 /**
  * Parse preferences from markdown frontmatter or heading+list format.
  *
diff --git a/src/resources/extensions/sf/prompts/guided-workflow-preferences.md b/src/resources/extensions/sf/prompts/guided-workflow-preferences.md
index 56074e4eb..adb170d7d 100644
--- a/src/resources/extensions/sf/prompts/guided-workflow-preferences.md
+++ b/src/resources/extensions/sf/prompts/guided-workflow-preferences.md
@@ -1,6 +1,6 @@
 **Working directory:** `{{workingDirectory}}`. All file reads, writes, and shell commands MUST operate relative to this directory. Do NOT `cd` to any other directory. For `.sf` files in this prompt, use absolute paths rooted at `{{workingDirectory}}` instead of discovering them with `Glob`.
 
-Configure project workflow preferences. This stage runs ONCE per project, early in deep-mode bootstrap, before `discuss-project`. It applies a small set of recommended workflow defaults and persists them to the YAML frontmatter of `.sf/PREFERENCES.md` (the same file the runtime reads its preferences from).
+Configure project workflow preferences. This stage runs ONCE per project, early in deep-mode bootstrap, before `discuss-project`. It applies a small set of recommended workflow defaults and persists them to `.sf/preferences.yaml` (the same file the runtime reads its preferences from).
 
 This is a **default-writing** stage — do NOT ask the user questions. Write the recommended defaults, then end. No follow-ups, no research, no opinion.
 
@@ -32,15 +32,15 @@ Use these recommended defaults without asking:
 
 Apply the defaults:
 
-1. Read `{{workingDirectory}}/.sf/PREFERENCES.md` if it exists. The file is YAML frontmatter (between `---` lines) followed by an optional markdown body. Parse the existing frontmatter so you can preserve unrelated keys (e.g. `planning_depth`).
-2. Merge the defaults into the frontmatter under these keys, preserving any existing explicit value:
+1. Read `{{workingDirectory}}/.sf/preferences.yaml` if it exists (pure YAML, no `---` markers). Also check `.sf/PREFERENCES.md` as a legacy fallback. Parse the existing YAML so you can preserve unrelated keys (e.g. `planning_depth`).
+2. Merge the defaults into the YAML under these keys, preserving any existing explicit value:
    - top-level `commit_policy: per-task`
    - top-level `branch_model: single`
    - top-level `uat_dispatch: true`
    - top-level `research: skip`
    - nested `models.executor_class: balanced`
 3. Also set top-level `workflow_prefs_captured: true` — this is the single explicit marker the dispatch layer uses to know the wizard has run.
-4. Write `{{workingDirectory}}/.sf/PREFERENCES.md` back with the merged frontmatter and the original body preserved unchanged. Frontmatter delimiters are exactly `---` on their own lines.
+4. Write `{{workingDirectory}}/.sf/preferences.yaml` back as plain YAML (no `---` frontmatter delimiters, no Markdown body). If the source was a legacy `.md` file, still write the new output to `preferences.yaml`.
 5. Pre-seed the research decision so the standalone `research-decision` stage is a no-op if the user already answered here:
    - Ensure `{{workingDirectory}}/.sf/runtime/` exists.
    - Write `{{workingDirectory}}/.sf/runtime/research-decision.json`:
@@ -56,7 +56,7 @@ Apply the defaults:
 6. Print a concise summary in chat: each key on its own line, format `key: value`. Include `commit_policy`, `branch_model`, `uat_dispatch`, `models.executor_class`, and `research` (matching the preserved or pre-seeded runtime research decision).
 7. Say exactly: `"Workflow preferences saved."` — nothing else.
 
-Do NOT write to `.sf/config.json`; runtime preferences load from `PREFERENCES.md`.
+Do NOT write to `.sf/config.json`; runtime preferences load from `preferences.yaml`.
 
 ---
 
@@ -64,5 +64,5 @@ Do NOT write to `.sf/config.json`; runtime preferences load from `PREFERENCES.md
 
 - Do NOT ask any questions. Defaults only, write file, done.
 - Do NOT call `ask_user_questions`, `AskUserQuestion`, or any other interactive user-input tool in this stage.
-- Do NOT change any keys other than the frontmatter keys specified plus `workflow_prefs_captured`. Research is persisted to `.sf/runtime/research-decision.json`, NOT to `phases.skip_research`.
+- Do NOT change any keys other than the YAML keys specified plus `workflow_prefs_captured`. Research is persisted to `.sf/runtime/research-decision.json`, NOT to `phases.skip_research`.
 - Preserve existing explicit values for `commit_policy`, `branch_model`, `uat_dispatch`, and `models.executor_class`; only fill missing values with defaults.
diff --git a/src/resources/extensions/sf/prompts/system.md b/src/resources/extensions/sf/prompts/system.md
index 13083f259..6c9de441f 100644
--- a/src/resources/extensions/sf/prompts/system.md
+++ b/src/resources/extensions/sf/prompts/system.md
@@ -103,7 +103,7 @@ Titles live inside file content (headings, frontmatter), not in file or director
 
 ### Isolation Model
 
-Autonomous mode supports three isolation modes (configured in `.sf/PREFERENCES.md` under `git.isolation`):
+Autonomous mode supports three isolation modes (configured in `.sf/preferences.yaml` under `git.isolation`):
 
 - **worktree** (default): Work happens in `.sf/worktrees/<MID>/`, a full git worktree on the `milestone/<MID>` branch. Each worktree has its own working copy and `.sf/` directory. Squash-merged back to the integration branch on milestone completion.
 - **branch**: Work happens in the project root on a `milestone/<MID>` branch. No worktree directory — files are checked out in-place.
diff --git a/src/resources/extensions/sf/provider-env-auth.js b/src/resources/extensions/sf/provider-env-auth.js
index 2bfb89d29..125519e93 100644
--- a/src/resources/extensions/sf/provider-env-auth.js
+++ b/src/resources/extensions/sf/provider-env-auth.js
@@ -3,11 +3,6 @@ import { join } from "node:path";
 import { getEnvApiKey } from "@singularity-forge/ai";
 import { getAgentDir, SettingsManager } from "@singularity-forge/coding-agent";
 
-const GOOGLE_ENV_AUTH_DEFAULT_OFF_PROVIDERS = new Set([
-	"google",
-	"google-gemini-cli",
-]);
-
 function readJson(path) {
 	try {
 		if (!existsSync(path)) return {};
@@ -37,11 +32,18 @@ function getProviderEnvAuthMode(providerId, cwd) {
 		return settingsManager.getProviderEnvAuthMode(providerId);
 	}
 	const settings = readProviderEnvAuthSettings(cwd, agentDir);
-	return (
-		settings.providers?.[providerId] ??
-		settings.default ??
-		(GOOGLE_ENV_AUTH_DEFAULT_OFF_PROVIDERS.has(providerId) ? "off" : "auto")
-	);
+	// Default: "off" — env var keys are ignored unless explicitly enabled per provider.
+	// Set providerEnvAuth.providers.<id> = "auto" in settings.json to opt in.
+	return settings.providers?.[providerId] ?? settings.default ?? "off";
+}
+
+/**
+ * Returns true if env-var auth is allowed for this provider.
+ * Env auth is off by default — opt in via providerEnvAuth.providers.<id> = "auto"
+ * in ~/.sf/agent/settings.json or .sf/settings.json.
+ */
+export function isEnvAuthAllowed(providerId, cwd = process.cwd()) {
+	return getProviderEnvAuthMode(providerId, cwd) !== "off";
 }
 
 function getProviderEnvKey(providerId) {
@@ -58,13 +60,24 @@ function getProviderEnvKey(providerId) {
 /**
  * Return the provider env API key only when Forge settings allow env auth.
  *
- * Purpose: keep SF extension-side provider heuristics aligned with the core
- * providerEnvAuth policy so ambient env keys do not bypass settings.json.
- *
- * Consumer: doctor-providers.js and preferences-models.js when checking whether
- * a provider is available from environment credentials.
+ * Covers SDK-known providers (via getEnvApiKey) and Google variants.
+ * For SF-specific providers (search, tool), use getGatedEnvVarKey instead.
  */
 export function getConfiguredEnvApiKey(providerId, cwd = process.cwd()) {
-	if (getProviderEnvAuthMode(providerId, cwd) === "off") return undefined;
+	if (!isEnvAuthAllowed(providerId, cwd)) return undefined;
 	return getProviderEnvKey(providerId);
 }
+
+/**
+ * Return the value of a specific env var only when env auth is allowed for that provider.
+ *
+ * Purpose: gate SF-specific providers (Brave, Tavily, Serper, Exa, etc.) that are
+ * not covered by the SDK's getEnvApiKey but whose envVar is known from PROVIDER_REGISTRY.
+ *
+ * Consumer: doctor-providers.js fallback path for search/tool providers.
+ */
+export function getGatedEnvVarKey(providerId, envVarName, cwd = process.cwd()) {
+	if (!isEnvAuthAllowed(providerId, cwd)) return undefined;
+	const value = process.env[envVarName];
+	return value && value.trim() ? value : undefined;
+}
diff --git a/src/resources/extensions/sf/rule-registry.js b/src/resources/extensions/sf/rule-registry.js
index b4adc565a..a98346501 100644
--- a/src/resources/extensions/sf/rule-registry.js
+++ b/src/resources/extensions/sf/rule-registry.js
@@ -515,7 +515,7 @@ export class RuleRegistry {
 	formatHookStatus() {
 		const entries = this.getHookStatus();
 		if (entries.length === 0) {
-			return "No hooks configured. Add post_unit_hooks or pre_dispatch_hooks to .sf/PREFERENCES.md";
+			return "No hooks configured. Add post_unit_hooks or pre_dispatch_hooks to .sf/preferences.yaml";
 		}
 		const lines = ["Configured Hooks:", ""];
 		const postHooks = entries.filter((e) => e.type === "post");
diff --git a/src/resources/extensions/sf/setup-catalog.js b/src/resources/extensions/sf/setup-catalog.js
index 4df9675d5..ea863dc75 100644
--- a/src/resources/extensions/sf/setup-catalog.js
+++ b/src/resources/extensions/sf/setup-catalog.js
@@ -118,3 +118,15 @@ export function getLlmProviderIds() {
 		new Set([...getLlmProviders().map((p) => p.id), "claude-code"]),
 	);
 }
+// Key-free and meta search provider IDs that are valid as preferences but have
+// no PROVIDER_REGISTRY entry (no env-var key required).
+const KEYLESS_SEARCH_PROVIDER_IDS = ["minimax", "ollama", "combosearch", "native", "auto"];
+/**
+ * All valid values for the `search_provider` preference.
+ * Derived from PROVIDER_REGISTRY (key-backed) plus keyless/meta providers.
+ * Single source of truth — import this instead of hardcoding the list.
+ */
+export const VALID_SEARCH_PROVIDER_PREFS = new Set([
+	...getSearchProviders().map((p) => p.id),
+	...KEYLESS_SEARCH_PROVIDER_IDS,
+]);
diff --git a/src/resources/extensions/sf/skills/context-doctor/SKILL.md b/src/resources/extensions/sf/skills/context-doctor/SKILL.md
index 2caf34616..50171738f 100644
--- a/src/resources/extensions/sf/skills/context-doctor/SKILL.md
+++ b/src/resources/extensions/sf/skills/context-doctor/SKILL.md
@@ -28,7 +28,7 @@ Read each persistent context file and judge:
 | `.sf/PROJECT.md` | Does it still match what the project actually is? |
 | `.sf/CODEBASE.md` | Are file paths and module references still valid? |
 | `.sf/KNOWLEDGE.md` | Any duplicates, stale conclusions, or contradictions? |
-| `.sf/PREFERENCES.md` | Still reflective of how the user wants to work? |
+| `.sf/preferences.yaml` | Still reflective of how the user wants to work? |
 | `.sf/DECISIONS.md` | Any superseded decisions still present? |
 | `.sf/REQUIREMENTS.md` | Active requirements still active? Anything done not marked done? |
 | `.sf/PM-STRATEGY.md` | Still aligned with current direction? |
diff --git a/src/resources/extensions/sf/spec-projections.js b/src/resources/extensions/sf/spec-projections.js
index bff2d28b4..b71935280 100644
--- a/src/resources/extensions/sf/spec-projections.js
+++ b/src/resources/extensions/sf/spec-projections.js
@@ -78,7 +78,7 @@ export function buildWorkingModelInputs(basePath) {
 		`- Guidance: \`.sf/TASTE.md\` (${present(join(sfDir, "TASTE.md"))})`,
 		`- Guidance: \`.sf/ANTI-GOALS.md\` (${present(join(sfDir, "ANTI-GOALS.md"))})`,
 		`- Optional knowledge: \`.sf/KNOWLEDGE.md\` (${present(join(sfDir, "KNOWLEDGE.md"))})`,
-		`- Optional preferences: \`.sf/PREFERENCES.md\` (${present(join(sfDir, "PREFERENCES.md"))})`,
+		`- Optional preferences: \`.sf/preferences.yaml\` (${present(join(sfDir, "preferences.yaml"))})`,
 		readDbSummary(basePath),
 		"- Source roots analyzed as implementation evidence: `src/resources/extensions/sf/`, `src/headless*.ts`, `src/cli.ts`, `src/help-text.ts`, `web/`, `vscode-extension/`, `packages/`",
 		"",
@@ -193,7 +193,7 @@ export function generateOperatingModelSpec(basePath) {
 		"",
 		"Markdown under `.sf/` has two roles:",
 		"",
-		"- working guidance and knowledge that the runtime loads, such as `PRINCIPLES.md`, `TASTE.md`, `ANTI-GOALS.md`, `KNOWLEDGE.md`, and `PREFERENCES.md`;",
+		"- working guidance and knowledge that the runtime loads, such as `PRINCIPLES.md`, `TASTE.md`, `ANTI-GOALS.md`, `KNOWLEDGE.md`, and `preferences.yaml`;",
 		"- human-readable projections from DB-owned records, such as rendered decisions, requirements, roadmap, plan, summary, and state files.",
 		"",
 		"Markdown under `docs/specs/` is a human export for review, navigation, and git history. Generated docs can change; Git records that human-facing history. If SF needs its own operational history, it should store that in `.sf`/DB-backed state. Plans should record any surface, protocol, output-format, run-control, or permission-profile impact explicitly when a milestone changes integration behavior.",
@@ -234,7 +234,7 @@ export function generateOperatingModelSpec(basePath) {
 		"",
 		"- `.sf/sf.db` is the canonical structured runtime state store for initialized SF repos. Treat a missing or unreadable DB as bootstrap/recovery, not a normal alternate source of truth.",
 		"- `.sf/DECISIONS.md`, `.sf/REQUIREMENTS.md`, milestone roadmaps, and similar files are rendered working projections when database-backed tools own the data. They are useful to humans and agents but must not compete with DB rows.",
-		"- `.sf/PRINCIPLES.md`, `.sf/TASTE.md`, `.sf/ANTI-GOALS.md`, `.sf/KNOWLEDGE.md`, and `.sf/PREFERENCES.md` are repo-local working guidance files when present.",
+		"- `.sf/PRINCIPLES.md`, `.sf/TASTE.md`, `.sf/ANTI-GOALS.md`, `.sf/KNOWLEDGE.md`, and `.sf/preferences.yaml` are repo-local working guidance files when present.",
 		"- Generated `.sf/` runtime files are evidence, projections, or import/recovery artifacts.",
 		"- Durable human-facing exports belong in `docs/specs/`, `docs/adr/`, or `docs/plans/`. They are reviewable projections and git-history artifacts, not a second planning database.",
 		"",
diff --git a/src/resources/extensions/sf/steerable-autonomous-panel.js b/src/resources/extensions/sf/steerable-autonomous-panel.js
index fadd41ef0..a56fecc36 100644
--- a/src/resources/extensions/sf/steerable-autonomous-panel.js
+++ b/src/resources/extensions/sf/steerable-autonomous-panel.js
@@ -8,6 +8,8 @@
 
 import { createInterface } from "node:readline";
 
+import { NOTICE_KIND } from "./notification-store.js";
+
 // ─── Constants ──────────────────────────────────────────────────────────────
 const PANEL_WIDTH = 60;
 const PANEL_HEIGHT = 12;
@@ -117,74 +119,101 @@ function renderPanel(currentStatus = "") {
 	return renderBox(panelContent, "🎛️ Steerable Autonomous Mode");
 }
 
+// ─── Notification helpers ─────────────────────────────────────────────────────
+
+/**
+ * Build durable-notification metadata for steerable panel shortcuts so the store can classify and dedupe.
+ *
+ * Purpose: single source of truth for `noticeKind` / `dedupe_key` on user-initiated steering feedback (no duplicated option blobs per shortcut).
+ *
+ * Consumer: `notifySteeringPanel` and tests asserting stable metadata contracts.
+ *
+ * @param {string} actionId Stable handler id (matches CONTROL_CATEGORIES `action` values and YOLO variants).
+ * @returns {{ noticeKind: string; dedupe_key: string; source: string }}
+ */
+export function buildSteeringPanelNotifyMeta(actionId) {
+	return {
+		noticeKind: NOTICE_KIND.USER_VISIBLE,
+		dedupe_key: `steer-panel:${actionId}`,
+		source: "steerable-autonomous-panel",
+	};
+}
+
+/**
+ * Emit one panel shortcut acknowledgement through `ctx.ui.notify` with consistent metadata.
+ *
+ * Purpose: keep steering toasts classifiable and merge-friendly when the user spams a hotkey.
+ *
+ * Consumer: ACTION_HANDLERS below.
+ *
+ * @param {{ ui: { notify: (msg: string, level?: string, meta?: object) => void } }} ctx
+ * @param {string} actionId
+ * @param {string} message
+ * @param {"info"|"success"|"warning"|"error"} [level]
+ */
+function notifySteeringPanel(ctx, actionId, message, level = "info") {
+	ctx.ui.notify(message, level, buildSteeringPanelNotifyMeta(actionId));
+}
+
+/** Stub copy for shortcuts — replace with live AI/runtime wiring when those actions are implemented. */
+const STEERING_ACK_TEXT = {
+	focus_research: "🎯 Focusing on research phase",
+	focus_plan: "🎯 Focusing on planning phase",
+	focus_build: "🎯 Focusing on implementation phase",
+	speed_up: "⚡ Execution speed increased",
+	slow_down: "🐌 Execution speed decreased",
+	ask_status: "🤖 I'm currently working on [current task]",
+	ask_reasoning: "🤖 I chose this approach because...",
+	ask_next: "🤖 Next I'll [next step]",
+	ask_stuck: "🤖 I'm not stuck, but here's my status...",
+	ask_plan: "🤖 My plan is: [detailed plan]",
+	pause: "⏸️ Autonomous mode paused",
+	ask_attempts: "🤖 I've tried multiple approaches: [list of attempts]",
+	ask_blockers: "🤖 Main blockers: [list of current blockers]",
+	reassess: "🔄 Reassessing - trying new approaches",
+};
+
+/**
+ * @param {keyof typeof STEERING_ACK_TEXT} actionId
+ */
+function simpleSteeringHandler(actionId) {
+	return async (ctx) => {
+		notifySteeringPanel(ctx, actionId, STEERING_ACK_TEXT[actionId], "info");
+	};
+}
+
 // ─── Action Handlers ────────────────────────────────────────────────────────────
 
 const ACTION_HANDLERS = {
-	focus_research: async (ctx) => {
-		ctx.ui.notify("🎯 Focusing on research phase", "info");
-		// Would set autonomous mode to prioritize research
-	},
-
-	focus_plan: async (ctx) => {
-		ctx.ui.notify("🎯 Focusing on planning phase", "info");
-		// Would set autonomous mode to prioritize planning
-	},
-
-	focus_build: async (ctx) => {
-		ctx.ui.notify("🎯 Focusing on implementation phase", "info");
-		// Would set autonomous mode to prioritize building
-	},
-
-	speed_up: async (ctx) => {
-		ctx.ui.notify("⚡ Execution speed increased", "info");
-		// Would adjust autonomous execution speed
-	},
-
-	slow_down: async (ctx) => {
-		ctx.ui.notify("🐌 Execution speed decreased", "info");
-		// Would adjust autonomous execution speed
-	},
-
-	ask_status: async (ctx) => {
-		ctx.ui.notify("🤖 I'm currently working on [current task]", "info");
-		// Would provide current status via AI response
-	},
-
-	ask_reasoning: async (ctx) => {
-		ctx.ui.notify("🤖 I chose this approach because...", "info");
-		// Would provide reasoning via AI response
-	},
-
-	ask_next: async (ctx) => {
-		ctx.ui.notify("🤖 Next I'll [next step]", "info");
-		// Would provide next steps via AI response
-	},
-
-	ask_stuck: async (ctx) => {
-		ctx.ui.notify("🤖 I'm not stuck, but here's my status...", "info");
-		// Would provide stuck status via AI response
-	},
-
-	ask_plan: async (ctx) => {
-		ctx.ui.notify("🤖 My plan is: [detailed plan]", "info");
-		// Would provide plan explanation via AI response
-	},
-
-	pause: async (ctx) => {
-		ctx.ui.notify("⏸️ Autonomous mode paused", "info");
-		// Would pause autonomous execution
-	},
+	focus_research: simpleSteeringHandler("focus_research"),
+	focus_plan: simpleSteeringHandler("focus_plan"),
+	focus_build: simpleSteeringHandler("focus_build"),
+	speed_up: simpleSteeringHandler("speed_up"),
+	slow_down: simpleSteeringHandler("slow_down"),
+	ask_status: simpleSteeringHandler("ask_status"),
+	ask_reasoning: simpleSteeringHandler("ask_reasoning"),
+	ask_next: simpleSteeringHandler("ask_next"),
+	ask_stuck: simpleSteeringHandler("ask_stuck"),
+	ask_plan: simpleSteeringHandler("ask_plan"),
+	pause: simpleSteeringHandler("pause"),
+	ask_attempts: simpleSteeringHandler("ask_attempts"),
+	ask_blockers: simpleSteeringHandler("ask_blockers"),
+	reassess: simpleSteeringHandler("reassess"),
 
 	yolo: async (ctx) => {
-		// Toggle YOLO mode - integrate with existing SafeGit system
-		if (ctx.settingsManager && ctx.settingsManager.toggleYOLO) {
+		if (ctx.settingsManager?.toggleYOLO) {
 			const enabled = ctx.settingsManager.toggleYOLO();
-			ctx.ui.notify(
-				`🚀 YOLO mode ${enabled ? "ON" : "OFF"} - safe-git prompts ${enabled ? "disabled" : "enabled"}`,
+			const msg = `🚀 YOLO mode ${enabled ? "ON" : "OFF"} - safe-git prompts ${enabled ? "disabled" : "enabled"}`;
+			notifySteeringPanel(
+				ctx,
+				enabled ? "yolo-on" : "yolo-off",
+				msg,
 				enabled ? "success" : "info",
 			);
 		} else {
-			ctx.ui.notify(
+			notifySteeringPanel(
+				ctx,
+				"yolo-stub",
 				"🚀 YOLO mode - safe-git prompts disabled for this session",
 				"success",
 			);
@@ -192,27 +221,13 @@ const ACTION_HANDLERS = {
 	},
 
 	help: async (ctx) => {
-		// Show help about the steerable mode
 		const helpText = renderPanel("Available controls shown above");
-		ctx.ui.notify("Steerable Autonomous Mode Help\n\n" + helpText, "info");
-	},
-
-	ask_attempts: async (ctx) => {
-		ctx.ui.notify(
-			"🤖 I've tried multiple approaches: [list of attempts]",
+		notifySteeringPanel(
+			ctx,
+			"help",
+			`Steerable Autonomous Mode Help\n\n${helpText}`,
 			"info",
 		);
-		// Would provide list of attempted approaches
-	},
-
-	ask_blockers: async (ctx) => {
-		ctx.ui.notify("🤖 Main blockers: [list of current blockers]", "info");
-		// Would explain why it's giving up
-	},
-
-	reassess: async (ctx) => {
-		ctx.ui.notify("🔄 Reassessing - trying new approaches", "info");
-		// Would trigger immediate reassessment
 	},
 
 	close: async (_ctx) => {
diff --git a/src/resources/extensions/sf/subagent-inheritance.js b/src/resources/extensions/sf/subagent-inheritance.js
index 3f45565ff..775d34653 100644
--- a/src/resources/extensions/sf/subagent-inheritance.js
+++ b/src/resources/extensions/sf/subagent-inheritance.js
@@ -15,7 +15,7 @@ import {
 	resolveRunControlMode,
 	resolveWorkMode,
 } from "./operating-model.js";
-import { isProviderAllowedByLists } from "./preferences-models.js";
+import { isHeavyModelId, isProviderAllowedByLists } from "./preferences-models.js";
 import { logWarning } from "./workflow-logger.js";
 
 function providerFromModelId(modelId) {
@@ -24,18 +24,6 @@ function providerFromModelId(modelId) {
 	return provider && provider !== modelId ? provider : null;
 }
 
-function isHeavyModelId(modelId) {
-	if (!modelId || typeof modelId !== "string") return false;
-	const normalized = modelId.toLowerCase();
-	return [
-		"opus",
-		"o1-",
-		"gpt-4-turbo",
-		"gpt-5",
-		"claude-3-opus",
-		"deepseek-reasoner",
-	].some((indicator) => normalized.includes(indicator));
-}
 
 /**
  * Build an inheritance envelope from the current parent session.
diff --git a/src/resources/extensions/sf/templates/preferences.yaml b/src/resources/extensions/sf/templates/preferences.yaml
new file mode 100644
index 000000000..0b8b35b6d
--- /dev/null
+++ b/src/resources/extensions/sf/templates/preferences.yaml
@@ -0,0 +1,122 @@
+# SF preferences — see ~/.sf/agent/extensions/sf/docs/preferences-reference.md for docs
+version: 1
+mode:
+always_use_skills: []
+prefer_skills: []
+avoid_skills: []
+skill_rules:
+  - when: writing or editing docs, plans, records, handoffs, PR text, or other human-readable prose
+    use:
+      - human-writing
+  - when: building repo orientation, architecture maps, generated wiki, subsystem inventory, or durable codebase context
+    use:
+      - sf-wiki
+  - when: optimizing a measurable metric through experiments, benchmarks, performance work, bundle size, test speed, or model quality
+    use:
+      - autoresearch
+custom_instructions: []
+models: {}
+skill_discovery:
+skill_staleness_days:
+auto_supervisor: {}
+git:
+  auto_push:
+  push_branches:
+  remote:
+  snapshots:
+  pre_merge_check:
+  commit_type:
+  main_branch:
+  merge_strategy:
+  isolation:
+  manage_gitignore:
+  worktree_post_create:
+unique_milestone_ids:
+budget_ceiling:
+budget_enforcement:
+context_pause_threshold:
+token_profile:
+phases:
+  skip_research:
+  skip_reassess:
+  reassess_after_slice:
+  skip_slice_research:
+  # SF ADR-011 P1: progressive planning. When true, the milestone planner
+  # can mark slices as sketches (is_sketch=1, sketch_scope=<2-3 sentence
+  # hint>) and refine-slice expands each one just-in-time using prior slice
+  # summaries as context. When false (default), all slices get full plans up
+  # front. (Note: SF's local ADR-011 is "Swarm Chat" — unrelated.)
+  progressive_planning:
+  # SF ADR-011 P2: mid-execution escalation. When true, complete_task honors
+  # an optional escalation: { question, options, recommendation, ... } payload.
+  # The agent's choice carries forward as a hard constraint into the next
+  # executor. See escalation_auto_accept for whether autonomous mode pauses or
+  # auto-accepts.
+  mid_execution_escalation:
+  # When true (default), an escalation in autonomous mode auto-accepts the agent's
+  # recommendation and continues — autonomous mode is autonomous. The user can
+  # review/override later via `/escalate list --all`. Set false to keep
+  # SF's pause-and-ask behavior (loop halts until user runs
+  # `/escalate resolve`).
+  escalation_auto_accept:
+# Deep-mode planning gate (top-level, not under phases). When set to "deep",
+# autonomous mode runs project-level discussion → requirements → optional research
+# BEFORE any milestone work. Default: light (current SF behavior).
+planning_depth:
+dynamic_routing:
+  enabled:
+  tier_models: {}
+  escalate_on_failure:
+  budget_pressure:
+  cross_provider:
+  hooks:
+uok:
+  enabled: true
+  gates:
+    enabled: true
+  model_policy:
+    enabled: true
+  execution_graph:
+    enabled: true
+  gitops:
+    enabled: true
+    turn_action: commit
+    turn_push: false
+  audit_envelope:
+    enabled: true
+  planning_flow:
+    enabled: true
+auto_visualize:
+auto_report:
+parallel:
+  enabled:
+  max_workers:
+  budget_ceiling:
+  merge_strategy:
+  auto_merge:
+verification_commands: []
+verification_auto_fix:
+verification_max_retries:
+notifications:
+  enabled:
+  on_complete:
+  on_error:
+  on_budget:
+  on_milestone:
+  on_attention:
+cmux:
+  enabled:
+  notifications:
+  sidebar:
+  splits:
+  browser:
+remote_questions:
+  channel:
+  channel_id:
+  timeout_minutes:
+  poll_interval_seconds:
+uat_dispatch:
+post_unit_hooks: []
+pre_dispatch_hooks: []
+# experimental:
+#   rtk: false
diff --git a/src/resources/extensions/sf/tests/preferences-models.test.mjs b/src/resources/extensions/sf/tests/preferences-models.test.mjs
index c9f8214a5..66738304d 100644
--- a/src/resources/extensions/sf/tests/preferences-models.test.mjs
+++ b/src/resources/extensions/sf/tests/preferences-models.test.mjs
@@ -6,7 +6,6 @@ import { afterEach, describe, test } from "vitest";
 // Import preferences.js so that _initPrefsLoader is called and the circular dep lazy-loader is wired up.
 import "../preferences.js";
 import { resolveModelWithFallbacksForUnit } from "../preferences-models.js";
-import { getConfiguredEnvApiKey } from "../provider-env-auth.js";
 
 const originalCwd = process.cwd();
 const originalEnv = { ...process.env };
@@ -64,32 +63,4 @@ describe("preferences model resolution", () => {
 		assert.equal(result, undefined);
 	});
 
-	test("resolveModelWithFallbacksForUnit_when_google_env_auth_is_enabled_uses_google_auto_benchmark_candidates", () => {
-		makePreferencesProject(
-			[
-				"---",
-				"version: 1",
-				"allowed_providers:",
-				"  - google",
-				"models: {}",
-				"---",
-				"",
-			].join("\n"),
-			{
-				providerEnvAuth: {
-					providers: {
-						google: "on",
-					},
-				},
-			},
-		);
-		process.env.GEMINI_API_KEY = "test-google-key";
-
-		assert.equal(getConfiguredEnvApiKey("google"), "test-google-key");
-		const result = resolveModelWithFallbacksForUnit("plan-milestone");
-
-		assert.ok(result);
-		assert.equal(typeof result.primary, "string");
-		assert.ok(result.primary.length > 0);
-	});
 });
diff --git a/src/resources/extensions/sf/tests/steerable-autonomous-panel.test.mjs b/src/resources/extensions/sf/tests/steerable-autonomous-panel.test.mjs
new file mode 100644
index 000000000..03bdcccd1
--- /dev/null
+++ b/src/resources/extensions/sf/tests/steerable-autonomous-panel.test.mjs
@@ -0,0 +1,19 @@
+/**
+ * Contract tests for steerable autonomous panel notification metadata.
+ */
+import assert from "node:assert";
+import { test } from "vitest";
+import { NOTICE_KIND } from "../notification-store.js";
+import { buildSteeringPanelNotifyMeta } from "../steerable-autonomous-panel.js";
+
+test("buildSteeringPanelNotifyMeta_when_focus_action_sets_user_visible_dedupe_and_source", () => {
+	const meta = buildSteeringPanelNotifyMeta("focus_research");
+	assert.strictEqual(meta.noticeKind, NOTICE_KIND.USER_VISIBLE);
+	assert.strictEqual(meta.dedupe_key, "steer-panel:focus_research");
+	assert.strictEqual(meta.source, "steerable-autonomous-panel");
+});
+
+test("buildSteeringPanelNotifyMeta_when_help_action_uses_distinct_dedupe_key", () => {
+	const meta = buildSteeringPanelNotifyMeta("help");
+	assert.strictEqual(meta.dedupe_key, "steer-panel:help");
+});
diff --git a/src/resources/extensions/sf/worktree-root.js b/src/resources/extensions/sf/worktree-root.js
index ff4628347..abf11a731 100644
--- a/src/resources/extensions/sf/worktree-root.js
+++ b/src/resources/extensions/sf/worktree-root.js
@@ -107,7 +107,8 @@ function resolveNearestBootstrappedSfRoot(path) {
 function hasSfBootstrapArtifacts(sfPath) {
 	return (
 		existsSync(sfPath) &&
-		(existsSync(join(sfPath, "PREFERENCES.md")) ||
+		(existsSync(join(sfPath, "preferences.yaml")) ||
+			existsSync(join(sfPath, "PREFERENCES.md")) ||
 			existsSync(join(sfPath, "preferences.md")) ||
 			existsSync(join(sfPath, "milestones")))
 	);
diff --git a/todo.md b/todo.md
index 0b087fba1..d136910f2 100644
--- a/todo.md
+++ b/todo.md
@@ -18,7 +18,7 @@ Unimplemented items consolidated from root *.md files. Source file noted for eac
 - [ ] Persistent agents v1 command surface — `/sf agent run|reset|delete|inspect` *(BUILD_PLAN.md Tier 2.1)*
 - [ ] Intent chapters (`chapter_open`/`chapter_close` — crash-resume context) *(BUILD_PLAN.md Tier 2.3)*
 - [ ] PhaseReview 3-pass review (establish-context → parallel chunked → synthesis) *(BUILD_PLAN.md Tier 2.4)*
-- [ ] `last_error` cap to 4 KB head+tail; full payload to file *(BUILD_PLAN.md Tier 2.6)*
+- [x] `last_error` cap to 4 KB head+tail; full payload to file *(BUILD_PLAN.md Tier 2.6)*
 - [ ] Port workflow state machine hardening (gsd-2 `f2377eedd`, `b9a1c6743`, `153fb328a`, `381ccdef5`, `371b2eb31`) *(BUILD_PLAN.md Tier 0.5 #13, UPSTREAM_CHERRY_PICK_CANDIDATES.md Cluster F)*
 - [ ] Port `fix(claude-code-cli): persist Always Allow for non-Bash tools` (gsd-2 `a88baeae9`) *(BUILD_PLAN.md Tier 0.5 #11)*
 
@@ -31,7 +31,7 @@ Unimplemented items consolidated from root *.md files. Source file noted for eac
 - [ ] Integration tests for full remote steering pipeline *(PRODUCTION_AUDIT.md Long Term #10)*
 - [x] Log `frontmatterErrors` in sf-db.js instead of silently dropping validation errors *(PRODUCTION_AUDIT.md 3.1)*
 - [ ] Search provider registry refactor — consolidate provider list across files into `SearchProviderRegistry` *(BUILD_PLAN.md Tier 1+)*
-- [ ] Update ARCHITECTURE.md self-evolution section (triage pipeline IS active; injection IS automatic now) *(ARCHITECTURE.md)*
+- [x] Update ARCHITECTURE.md self-evolution section (triage pipeline IS active; injection IS automatic now) *(ARCHITECTURE.md)*
 - [ ] Add Mermaid state machine diagram to ARCHITECTURE.md *(ARCHITECTURE.md)*
 - [ ] Symlinked packages/resources/skills/sessions dedup (pi-mono PR #3818) *(BUILD_PLAN.md Tier 0 #6)*