diff --git a/src/resources/extensions/sf/commands/catalog.js b/src/resources/extensions/sf/commands/catalog.js
index 24a12abc2..af44f23c7 100644
--- a/src/resources/extensions/sf/commands/catalog.js
+++ b/src/resources/extensions/sf/commands/catalog.js
@@ -248,6 +248,35 @@ export const TOP_LEVEL_SUBCOMMANDS = [
 		cmd: "plan",
 		desc: "Promote planning artifacts from ~/.sf/ to docs/ (promote, list, diff)",
 	},
+	{
+		cmd: "experimental",
+		desc: "Toggle experimental feature flags (show/on/off/on <flag>/off <flag>)",
+	},
+	{ cmd: "diff", desc: "Show git diff (HEAD by default, --staged for staged)" },
+	{ cmd: "theme", desc: "Get or set the UI theme (dark/light/dim/auto)" },
+	{ cmd: "rename", desc: "Rename the current session (sets terminal title)" },
+	{
+		cmd: "streamer-mode",
+		desc: "Toggle streamer mode — masks model names and quota details",
+	},
+	{
+		cmd: "statusline",
+		desc: "Configure the status line script (script <path> | off)",
+	},
+	{ cmd: "search", desc: "Search the session timeline for a query" },
+	{ cmd: "find", desc: "Alias for /search — search the session timeline" },
+	{
+		cmd: "chronicle",
+		desc: "Show session chronicle (recent git log + session events)",
+	},
+	{
+		cmd: "rewind",
+		desc: "Rewind the last turn and revert its file changes",
+	},
+	{
+		cmd: "instructions",
+		desc: "List instruction files loaded into the agent context",
+	},
 ];
 
 export const DIRECT_SF_COMMANDS = TOP_LEVEL_SUBCOMMANDS.filter(
diff --git a/src/resources/extensions/sf/commands/handlers/core.js b/src/resources/extensions/sf/commands/handlers/core.js
index e5c82686e..13002ab7f 100644
--- a/src/resources/extensions/sf/commands/handlers/core.js
+++ b/src/resources/extensions/sf/commands/handlers/core.js
@@ -8,6 +8,13 @@ import {
 	handlePrefsWizard,
 } from "../../commands-prefs-wizard.js";
 import { runEnvironmentChecks } from "../../doctor-environment.js";
+import {
+	EXPERIMENTAL_FLAGS,
+	getAllExperimentalFlags,
+	getExperimentalFlag,
+	setAllExperimentalFlags,
+	setExperimentalFlag,
+} from "../../experimental.js";
 import {
 	getGlobalSFPreferencesPath,
 	getProjectSFPreferencesPath,
@@ -768,8 +775,448 @@ export async function handleCoreCommand(trimmed, ctx, pi) {
 		ctx.ui.notify(lines.join("\n"), "info");
 		return true;
 	}
+	if (trimmed === "experimental" || trimmed.startsWith("experimental ")) {
+		await handleExperimentalCommand(
+			trimmed.replace(/^experimental\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
+	if (trimmed === "diff" || trimmed.startsWith("diff ")) {
+		await handleDiffCommand(trimmed.replace(/^diff\s*/, "").trim(), ctx);
+		return true;
+	}
+	if (trimmed === "theme" || trimmed.startsWith("theme ")) {
+		await handleThemeCommand(trimmed.replace(/^theme\s*/, "").trim(), ctx);
+		return true;
+	}
+	if (trimmed === "rename" || trimmed.startsWith("rename ")) {
+		await handleRenameCommand(trimmed.replace(/^rename\s*/, "").trim(), ctx);
+		return true;
+	}
+	if (trimmed === "streamer-mode" || trimmed.startsWith("streamer-mode ")) {
+		await handleStreamerModeCommand(
+			trimmed.replace(/^streamer-mode\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
+	if (
+		trimmed === "statusline" ||
+		trimmed.startsWith("statusline ") ||
+		trimmed === "footer-config" ||
+		trimmed.startsWith("footer-config ")
+	) {
+		await handleStatuslineCommand(
+			trimmed.replace(/^(?:statusline|footer-config)\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
+	if (
+		trimmed === "search" ||
+		trimmed.startsWith("search ") ||
+		trimmed === "find" ||
+		trimmed.startsWith("find ")
+	) {
+		const query = trimmed.replace(/^(?:search|find)\s*/, "").trim();
+		await handleSearchCommand(query, ctx);
+		return true;
+	}
+	if (trimmed === "chronicle" || trimmed.startsWith("chronicle ")) {
+		await handleChronicleCommand(
+			trimmed.replace(/^chronicle\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
+	if (trimmed === "rewind" || trimmed === "undo-turn") {
+		await handleRewindCommand(ctx);
+		return true;
+	}
+	if (trimmed === "instructions" || trimmed.startsWith("instructions ")) {
+		await handleInstructionsCommand(
+			trimmed.replace(/^instructions\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
+	if (trimmed === "session-rename" || trimmed.startsWith("session-rename ")) {
+		// Alias for /rename
+		await handleRenameCommand(
+			trimmed.replace(/^session-rename\s*/, "").trim(),
+			ctx,
+		);
+		return true;
+	}
 	return false;
 }
+
+// ─── /experimental ──────────────────────────────────────────────────────────
+
+async function handleExperimentalCommand(args, ctx) {
+	const sub = args.trim();
+
+	if (!sub || sub === "show") {
+		const current = getAllExperimentalFlags();
+		const lines = ["Experimental features\n"];
+		for (const [name, desc] of Object.entries(EXPERIMENTAL_FLAGS)) {
+			const on = current[name] === true;
+			lines.push(`  ${on ? "✓" : "○"} ${name.padEnd(22)} ${desc}`);
+		}
+		lines.push(
+			"\nUsage: /experimental on [flag]  /experimental off [flag]  /experimental on (all)",
+		);
+		ctx.ui.notify(lines.join("\n"), "info");
+		return;
+	}
+
+	if (sub === "on") {
+		setAllExperimentalFlags(true);
+		ctx.ui.notify("All experimental features enabled.", "info");
+		return;
+	}
+	if (sub === "off") {
+		setAllExperimentalFlags(false);
+		ctx.ui.notify("All experimental features disabled.", "info");
+		return;
+	}
+
+	const onMatch = sub.match(/^on\s+(\S+)$/);
+	if (onMatch) {
+		const flag = onMatch[1];
+		if (!EXPERIMENTAL_FLAGS[flag]) {
+			ctx.ui.notify(
+				`Unknown flag "${flag}". Run /experimental show for the list.`,
+				"warning",
+			);
+			return;
+		}
+		setExperimentalFlag(flag, true);
+		ctx.ui.notify(`${flag} enabled.`, "info");
+		return;
+	}
+
+	const offMatch = sub.match(/^off\s+(\S+)$/);
+	if (offMatch) {
+		const flag = offMatch[1];
+		if (!EXPERIMENTAL_FLAGS[flag]) {
+			ctx.ui.notify(
+				`Unknown flag "${flag}". Run /experimental show for the list.`,
+				"warning",
+			);
+			return;
+		}
+		setExperimentalFlag(flag, false);
+		ctx.ui.notify(`${flag} disabled.`, "info");
+		return;
+	}
+
+	// Unknown sub-command — show usage
+	ctx.ui.notify(
+		"Usage: /experimental [show|on|off|on <flag>|off <flag>]",
+		"info",
+	);
+}
+
+// ─── /diff ──────────────────────────────────────────────────────────────────
+
+async function handleDiffCommand(args, ctx) {
+	const { execSync } = await import("node:child_process");
+	const staged = args === "--staged" || args === "--cached";
+	try {
+		const cmd = staged ? "git diff --staged" : "git diff HEAD";
+		const output = execSync(cmd, {
+			cwd: projectRoot(),
+			encoding: "utf-8",
+			stdio: ["pipe", "pipe", "pipe"],
+		});
+		if (!output.trim()) {
+			ctx.ui.notify(
+				staged ? "No staged changes." : "No changes since last commit.",
+				"info",
+			);
+			return;
+		}
+		ctx.ui.notify(output.slice(0, 8000), "info");
+	} catch (e) {
+		ctx.ui.notify(`git diff failed: ${e.message}`, "error");
+	}
+}
+
+// ─── /theme ─────────────────────────────────────────────────────────────────
+
+async function handleThemeCommand(args, ctx) {
+	const THEMES = ["dark", "light", "dim", "auto"];
+	const { loadEffectiveSFPreferences } = await import("../../preferences.js");
+	const { extractBodyAfterFrontmatter, serializePreferencesToFrontmatter } =
+		await import("../../commands-prefs-wizard.js");
+	const { readFileSync, writeFileSync, existsSync } = await import("node:fs");
+
+	if (!args) {
+		const current = loadEffectiveSFPreferences()?.preferences?.theme ?? "auto";
+		ctx.ui.notify(
+			`Current theme: ${current}\nOptions: ${THEMES.join(" | ")}\nUsage: /theme <name>`,
+			"info",
+		);
+		return;
+	}
+	if (!THEMES.includes(args)) {
+		ctx.ui.notify(
+			`Unknown theme "${args}". Options: ${THEMES.join(", ")}`,
+			"warning",
+		);
+		return;
+	}
+	const path = getProjectSFPreferencesPath();
+	const { loadProjectSFPreferences } = await import("../../preferences.js");
+	const existing = loadProjectSFPreferences();
+	const prefs = existing?.preferences ? { ...existing.preferences } : {};
+	prefs.version = prefs.version || 1;
+	prefs.theme = args;
+	const frontmatter = serializePreferencesToFrontmatter(prefs);
+	let body =
+		"\n# SF Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full documentation.\n";
+	if (existsSync(path)) {
+		const preserved = extractBodyAfterFrontmatter(readFileSync(path, "utf-8"));
+		if (preserved) body = preserved;
+	}
+	const { mkdirSync } = await import("node:fs");
+	const { dirname } = await import("node:path");
+	mkdirSync(dirname(path), { recursive: true });
+	writeFileSync(path, `---\n${frontmatter}---${body}`, "utf-8");
+	ctx.ui.notify(`Theme set to "${args}". Restart SF to apply.`, "info");
+}
+
+// ─── /rename ────────────────────────────────────────────────────────────────
+
+async function handleRenameCommand(name, ctx) {
+	if (!name) {
+		ctx.ui.notify(
+			"Usage: /rename <session name>\nProvide a name for the current session.",
+			"info",
+		);
+		return;
+	}
+	// Write terminal title via OSC 2
+	process.stdout.write(`\x1b]2;${name} — SF\x07`);
+	// Store in session metadata if auto-session is available
+	try {
+		const session = getAutoSession();
+		if (session?.setName) {
+			session.setName(name);
+		}
+	} catch {
+		/* session metadata not available in all modes */
+	}
+	ctx.ui.notify(`Session renamed to "${name}".`, "info");
+}
+
+// ─── /streamer-mode ─────────────────────────────────────────────────────────
+
+async function handleStreamerModeCommand(args, ctx) {
+	const isOn = getExperimentalFlag("streamer_mode");
+	if (args === "on" || (!args && !isOn)) {
+		setExperimentalFlag("streamer_mode", true);
+		ctx.ui.notify(
+			"Streamer mode ON — model names and quota details are masked.",
+			"info",
+		);
+	} else if (args === "off" || (!args && isOn)) {
+		setExperimentalFlag("streamer_mode", false);
+		ctx.ui.notify("Streamer mode OFF.", "info");
+	} else {
+		const state = isOn ? "ON" : "OFF";
+		ctx.ui.notify(
+			`Streamer mode is ${state}.\nUsage: /streamer-mode [on|off]`,
+			"info",
+		);
+	}
+}
+
+// ─── /statusline ────────────────────────────────────────────────────────────
+
+async function handleStatuslineCommand(args, ctx) {
+	if (args.startsWith("script ")) {
+		const scriptPath = args.slice(7).trim();
+		setExperimentalFlag("status_line_script", scriptPath);
+		setExperimentalFlag("status_line", true);
+		ctx.ui.notify(
+			`Status line script set to: ${scriptPath}\nSTATUS_LINE enabled.`,
+			"info",
+		);
+		return;
+	}
+	if (args === "off") {
+		setExperimentalFlag("status_line", false);
+		ctx.ui.notify("Status line script disabled.", "info");
+		return;
+	}
+	ctx.ui.notify(
+		[
+			"Status line configuration",
+			"",
+			"  /statusline script <path>   Set user-defined script path",
+			"  /statusline off             Disable status line script",
+			"",
+			"The script is run every 5 seconds. Its stdout becomes a footer status chip.",
+			`STATUS_LINE flag: ${getExperimentalFlag("status_line") ? "ON" : "OFF"}`,
+		].join("\n"),
+		"info",
+	);
+}
+
+// ─── /search /find ──────────────────────────────────────────────────────────
+
+async function handleSearchCommand(query, ctx) {
+	// Gracefully degrade when session manager is unavailable (headless mode)
+	try {
+		const { getSessionManager } = await import(
+			"../../session-manager.js"
+		).catch(() => ({ getSessionManager: null }));
+		if (!getSessionManager) {
+			ctx.ui.notify(
+				"Session search is not available in headless mode.",
+				"info",
+			);
+			return;
+		}
+		const entries = getSessionManager?.()?.getEntries?.() ?? [];
+		const term = query.toLowerCase();
+		const matches = entries
+			.filter((e) => {
+				const text = (
+					typeof e.content === "string"
+						? e.content
+						: JSON.stringify(e.content ?? "")
+				).toLowerCase();
+				return term ? text.includes(term) : true;
+			})
+			.slice(0, 20);
+		if (matches.length === 0) {
+			ctx.ui.notify(`No results for "${query}".`, "info");
+			return;
+		}
+		const lines = [`Search: "${query}" — ${matches.length} result(s)\n`];
+		for (const m of matches) {
+			const snippet =
+				typeof m.content === "string"
+					? m.content.slice(0, 120).replace(/\n/g, " ")
+					: JSON.stringify(m.content).slice(0, 120);
+			lines.push(`  [${m.type ?? "entry"}] ${snippet}`);
+		}
+		ctx.ui.notify(lines.join("\n"), "info");
+	} catch (e) {
+		ctx.ui.notify(`Search failed: ${e.message}`, "error");
+	}
+}
+
+// ─── /chronicle ─────────────────────────────────────────────────────────────
+
+async function handleChronicleCommand(args, ctx) {
+	try {
+		const { readSFDb } = await import("../../sf-db.js").catch(() => ({
+			readSFDb: null,
+		}));
+		if (!readSFDb) {
+			ctx.ui.notify(
+				"Chronicle requires the SF database. Run /init first.",
+				"warning",
+			);
+			return;
+		}
+		const { execSync } = await import("node:child_process");
+		const lines = ["Session Chronicle\n"];
+		// Git log for recent activity
+		try {
+			const gitLog = execSync(
+				"git log --oneline --no-merges -20 2>/dev/null || true",
+				{ cwd: projectRoot(), encoding: "utf-8" },
+			);
+			if (gitLog.trim()) {
+				lines.push("Recent commits:");
+				lines.push(gitLog.trim());
+				lines.push("");
+			}
+		} catch {
+			/* non-fatal */
+		}
+
+		if (args.startsWith("search ")) {
+			const term = args.slice(7).trim();
+			ctx.ui.notify(
+				`Chronicle search for "${term}" — use /search for session entry search.`,
+				"info",
+			);
+			return;
+		}
+		lines.push("Tip: /search <query> searches the current session timeline.");
+		ctx.ui.notify(lines.join("\n"), "info");
+	} catch (e) {
+		ctx.ui.notify(`Chronicle failed: ${e.message}`, "error");
+	}
+}
+
+// ─── /rewind ────────────────────────────────────────────────────────────────
+
+async function handleRewindCommand(ctx) {
+	try {
+		const reverted = await ctx.rewind?.();
+		if (reverted) {
+			ctx.ui.notify(
+				"Rewound last turn. File changes from that turn have been reverted.",
+				"info",
+			);
+		} else {
+			ctx.ui.notify(
+				"Rewind is not available in this context. Use /undo to revert the last completed unit.",
+				"info",
+			);
+		}
+	} catch {
+		ctx.ui.notify(
+			"Rewind is not available. Use /undo to revert the last completed unit.",
+			"info",
+		);
+	}
+}
+
+// ─── /instructions ──────────────────────────────────────────────────────────
+
+async function handleInstructionsCommand(_args, ctx) {
+	const { existsSync } = await import("node:fs");
+	const { join: pathJoin } = await import("node:path");
+	const { homedir } = await import("node:os");
+	const root = projectRoot();
+	const home = homedir();
+
+	const candidates = [
+		{ label: "AGENTS.md", path: pathJoin(root, "AGENTS.md") },
+		{ label: "CLAUDE.md", path: pathJoin(root, "CLAUDE.md") },
+		{ label: "GEMINI.md", path: pathJoin(root, "GEMINI.md") },
+		{
+			label: ".github/copilot-instructions.md",
+			path: pathJoin(root, ".github", "copilot-instructions.md"),
+		},
+		{
+			label: "~/.copilot/copilot-instructions.md",
+			path: pathJoin(home, ".copilot", "copilot-instructions.md"),
+		},
+	];
+
+	const lines = ["Instruction files\n"];
+	for (const c of candidates) {
+		const exists = existsSync(c.path);
+		lines.push(
+			`  ${exists ? "✓" : "○"} ${c.label}${exists ? "" : " (not found)"}`,
+		);
+	}
+	lines.push(
+		"\nAll existing files are loaded automatically. Delete or rename to disable.",
+	);
+	ctx.ui.notify(lines.join("\n"), "info");
+}
+
 export function formatTextStatus(state) {
 	const lines = ["SF Status\n"];
 	lines.push(formatProgressLine(computeProgressScore()));
diff --git a/src/resources/extensions/sf/experimental.js b/src/resources/extensions/sf/experimental.js
new file mode 100644
index 000000000..78f82b8dd
--- /dev/null
+++ b/src/resources/extensions/sf/experimental.js
@@ -0,0 +1,105 @@
+/**
+ * experimental.js — Feature flag helpers for SF experimental features.
+ *
+ * Purpose: single read/write surface for prefs.experimental flags so that
+ * every gated feature calls getExperimentalFlag(name) rather than reaching
+ * into preferences directly.
+ *
+ * Consumer: /experimental command handler, all features gated by flags.
+ */
+
+import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
+import { dirname } from "node:path";
+import {
+	extractBodyAfterFrontmatter,
+	serializePreferencesToFrontmatter,
+} from "./commands-prefs-wizard.js";
+import {
+	getProjectSFPreferencesPath,
+	loadEffectiveSFPreferences,
+	loadProjectSFPreferences,
+} from "./preferences.js";
+
+/** All recognized experimental feature flags with descriptions. */
+export const EXPERIMENTAL_FLAGS = {
+	status_line:
+		"STATUS_LINE — run a user-defined script to feed a custom footer status chip",
+	show_file:
+		"SHOW_FILE — show_file tool renders code snippets inline in the timeline",
+	ask_elicitation:
+		"ASK_USER_ELICITATION — structured form/select UI replaces plain ask_user",
+	multi_turn_agents:
+		"MULTI_TURN_AGENTS — persistent subagents that accept follow-up messages",
+	extensions:
+		"EXTENSIONS — user-installable extensions via marketplace npm install",
+	configure_agent:
+		"CONFIGURE_COPILOT_AGENT — interactive wizard for MCP servers and agents",
+	background_sessions:
+		"BACKGROUND_SESSIONS — concurrent sessions with background switching",
+	rubber_duck:
+		"RUBBER_DUCK — constructive feedback subagent on code and designs",
+	prompt_frame:
+		"PROMPT_FRAME — decorative border rendered above the input prompt",
+	streamer_mode:
+		"STREAMER_MODE — mask model names and quota details for screen sharing",
+};
+
+/**
+ * Read a single experimental flag from the effective (merged) preferences.
+ * Returns true only when the flag is explicitly set to true.
+ *
+ * Purpose: cheap, consistent read path for all feature-gated code paths.
+ * Consumer: every feature behind an experimental flag.
+ */
+export function getExperimentalFlag(name) {
+	const prefs = loadEffectiveSFPreferences();
+	return prefs?.preferences?.experimental?.[name] === true;
+}
+
+/**
+ * Read all experimental flags from the effective preferences.
+ *
+ * Purpose: /experimental show lists every flag and its current state.
+ * Consumer: handleExperimentalCommand (show sub-command).
+ */
+export function getAllExperimentalFlags() {
+	const prefs = loadEffectiveSFPreferences();
+	return prefs?.preferences?.experimental ?? {};
+}
+
+/**
+ * Write a single experimental flag to the project preferences file.
+ * Creates the file if it does not exist. Preserves all other fields.
+ *
+ * Purpose: /experimental on <flag> / off <flag> writes back cleanly.
+ * Consumer: handleExperimentalCommand.
+ */
+export function setExperimentalFlag(name, value) {
+	const path = getProjectSFPreferencesPath();
+	const existing = loadProjectSFPreferences();
+	const prefs = existing?.preferences ? { ...existing.preferences } : {};
+	prefs.version = prefs.version || 1;
+	prefs.experimental = { ...(prefs.experimental ?? {}), [name]: value };
+
+	const frontmatter = serializePreferencesToFrontmatter(prefs);
+	let body =
+		"\n# SF Preferences\n\nSee `~/.sf/agent/extensions/sf/docs/preferences-reference.md` for full documentation.\n";
+	if (existsSync(path)) {
+		const preserved = extractBodyAfterFrontmatter(readFileSync(path, "utf-8"));
+		if (preserved) body = preserved;
+	}
+	mkdirSync(dirname(path), { recursive: true });
+	writeFileSync(path, `---\n${frontmatter}---${body}`, "utf-8");
+}
+
+/**
+ * Enable or disable all known experimental flags in one call.
+ *
+ * Purpose: /experimental on (no flag arg) bulk-enables all flags.
+ * Consumer: handleExperimentalCommand bulk toggle.
+ */
+export function setAllExperimentalFlags(value) {
+	for (const name of Object.keys(EXPERIMENTAL_FLAGS)) {
+		setExperimentalFlag(name, value);
+	}
+}