diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index be74683c1..c4a9c757a 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -12,6 +12,7 @@
 
 - Fixed idle Loader animations on WSL repeatedly entering render scheduling after an expired ConPTY post-paint settle window instead of resuming direct component writes ([#6024](https://github.com/can1357/oh-my-pi/issues/6024)).
 - Prevented canonical slash commands and their matching aliases from appearing as duplicate autocomplete rows ([#6131](https://github.com/can1357/oh-my-pi/issues/6131)).
+- Fixed Ctrl+L appearance refreshes inside tmux reading tmux's stale OSC 11 background cache instead of querying the outer terminal when passthrough is enabled ([#6066](https://github.com/can1357/oh-my-pi/issues/6066)).
 
 ## [17.0.5] - 2026-07-18
 
diff --git a/packages/tui/src/terminal.ts b/packages/tui/src/terminal.ts
index aa640676a..d0e48aa92 100644
--- a/packages/tui/src/terminal.ts
+++ b/packages/tui/src/terminal.ts
@@ -18,6 +18,7 @@ import {
 	setOsc99Supported,
 	TERMINAL,
 } from "./terminal-capabilities";
+import { isInsideTmux, wrapTmuxPassthrough } from "./tmux";
 import { type HangulCompatibilityJamoWidth, setHangulCompatibilityJamoWidth } from "./utils";
 
 const TERMINAL_PROGRESS_KEEPALIVE_MS = 1000;
@@ -456,6 +457,7 @@ function parseOsc99KeyValues(section: string): Map<string, string> {
 	return values;
 }
 const XTERM_SCROLL_TO_BOTTOM_MODES = [1010, 1011] as const;
+type Osc11QueryRoute = "direct" | "tmux";
 
 function isXtermScrollToBottomMode(mode: number): boolean {
 	return mode === 1010 || mode === 1011;
@@ -509,7 +511,7 @@ export class ProcessTerminal implements Terminal {
 	#appearanceCallbacks: Array<(appearance: TerminalAppearance) => void> = [];
 	#appearance: TerminalAppearance | undefined;
 	#osc11Pending = false;
-	#osc11QueryQueued = false;
+	#osc11QueuedRoute?: Osc11QueryRoute;
 	#osc11ResponseBuffer = "";
 	#osc99PendingId: string | undefined;
 	#osc99ResponseBuffer = "";
@@ -572,15 +574,15 @@ export class ProcessTerminal implements Terminal {
 
 	/**
 	 * Re-query the terminal background via a single OSC 11 probe. Reuses the
-	 * startup query path — same DA1-sentinel FIFO, pending/queued gating, parsing,
-	 * dedup, and appearance callbacks — so a light/dark switch is picked up
-	 * without a restart on terminals lacking end-to-end Mode 2031 notifications.
-	 * Bounded to one probe per call; no timers are armed. Suppressed while headless
-	 * or after the terminal is torn down.
+	 * startup DA1-sentinel FIFO, pending/queued gating, parsing, dedup, and
+	 * appearance callbacks. Inside tmux, only this explicit path wraps the query
+	 * and sentinel together for passthrough to the outer terminal; startup and
+	 * Mode 2031 probes remain direct. Bounded to one probe per call; no timers are
+	 * armed. Suppressed while headless or after the terminal is torn down.
 	 */
 	refreshAppearance(): void {
 		if (this.#headless || this.#dead) return;
-		this.#queryBackgroundColor();
+		this.#queryBackgroundColor(isInsideTmux() ? "tmux" : "direct");
 	}
 
 	onPrivateModeReport(callback: (mode: number, supported: boolean, confirmed?: boolean) => void): void {
@@ -917,13 +919,14 @@ export class ProcessTerminal implements Terminal {
 						}
 						// Start a queued OSC 11 query once the prior cycle is fully drained.
 						if (
-							this.#osc11QueryQueued &&
+							this.#osc11QueuedRoute !== undefined &&
 							!this.#osc11Pending &&
 							!this.#da1SentinelOwners.some(o => o.kind === "osc11") &&
 							!this.#dead
 						) {
-							this.#osc11QueryQueued = false;
-							this.#startOsc11Query();
+							const route = this.#osc11QueuedRoute;
+							this.#osc11QueuedRoute = undefined;
+							this.#startOsc11Query(route);
 						}
 						break;
 					}
@@ -1058,23 +1061,28 @@ export class ProcessTerminal implements Terminal {
 	 * DA1 avoids indefinite hangs: if DA1 response arrives before OSC 11,
 	 * the terminal does not support OSC 11.
 	 */
-	#queryBackgroundColor(): void {
+	#queryBackgroundColor(route: Osc11QueryRoute = "direct"): void {
 		if (this.#dead) return;
 		// Queue if an OSC 11 query is in flight or its DA1 sentinel hasn't been
 		// consumed yet. Starting a new query while a DA1 is outstanding would
 		// increment the sentinel counter, and the old DA1 arrival would then
-		// prematurely clear the new query's pending state.
+		// prematurely clear the new query's pending state. Preserve a requested
+		// tmux passthrough route when coalescing direct and explicit queries.
 		if (this.#osc11Pending || this.#da1SentinelOwners.some(o => o.kind === "osc11")) {
-			this.#osc11QueryQueued = true;
+			if (this.#osc11QueuedRoute !== "tmux") this.#osc11QueuedRoute = route;
 			return;
 		}
-		this.#startOsc11Query();
+		this.#startOsc11Query(route);
 	}
 
-	#startOsc11Query(): void {
+	#startOsc11Query(route: Osc11QueryRoute): void {
 		this.#osc11Pending = true;
 		this.#osc11ResponseBuffer = "";
 		this.#da1SentinelOwners.push({ kind: "osc11" });
+		if (route === "tmux") {
+			this.#safeWrite(wrapTmuxPassthrough("\x1b]11;?\x07\x1b[c"));
+			return;
+		}
 		this.#safeWrite("\x1b]11;?\x07"); // OSC 11 query (BEL terminated)
 		this.#safeWrite("\x1b[c"); // DA1 sentinel
 	}
@@ -1397,7 +1405,7 @@ export class ProcessTerminal implements Terminal {
 		this.#appearanceCallbacks = [];
 		this.#osc11Pending = false;
 		this.#clearWindowsTerminalAppearancePoll();
-		this.#osc11QueryQueued = false;
+		this.#osc11QueuedRoute = undefined;
 		this.#osc11ResponseBuffer = "";
 		this.#osc99PendingId = undefined;
 		this.#osc99ResponseBuffer = "";
diff --git a/packages/tui/test/terminal-appearance.test.ts b/packages/tui/test/terminal-appearance.test.ts
index dcd2900df..96d98a147 100644
--- a/packages/tui/test/terminal-appearance.test.ts
+++ b/packages/tui/test/terminal-appearance.test.ts
@@ -19,6 +19,7 @@ const originalWslDistroName = Bun.env.WSL_DISTRO_NAME;
 const originalWslInterop = Bun.env.WSL_INTEROP;
 const originalWtSession = Bun.env.WT_SESSION;
 const originalTermProgram = Bun.env.TERM_PROGRAM;
+const originalTmux = Bun.env.TMUX;
 
 // These suites drive the real ProcessTerminal start()/probe pipeline, so they
 // opt out of the test-default headless suppression and restore it per case.
@@ -60,6 +61,7 @@ describe("ProcessTerminal OSC 11 appearance detection", () => {
 		restoreEnv("WSL_DISTRO_NAME", originalWslDistroName);
 		restoreEnv("WT_SESSION", originalWtSession);
 		restoreEnv("TERM_PROGRAM", originalTermProgram);
+		restoreEnv("TMUX", originalTmux);
 	});
 
 	function setupTerminal() {
@@ -282,6 +284,22 @@ describe("ProcessTerminal OSC 11 appearance detection", () => {
 		terminal.stop();
 	});
 
+	it("passes an explicit appearance refresh through tmux without changing the startup probe", () => {
+		Bun.env.TMUX = "/tmp/tmux-1000/default,1234,0";
+		const { terminal, writes } = setupTerminal();
+
+		expect(writes).toContain("\x1b]11;?\x07");
+		expect(writes).toContain("\x1b[c");
+
+		process.stdin.emit("data", "\x1b]11;rgb:ffff/ffff/ffff\x07");
+		for (let i = 0; i < 7; i++) process.stdin.emit("data", "\x1b[?1;2c");
+		terminal.refreshAppearance?.();
+
+		expect(writes).toContain("\x1bPtmux;\x1b\x1b]11;?\x07\x1b\x1b[c\x1b\\");
+
+		terminal.stop();
+	});
+
 	it("refreshAppearance() re-evaluates a changed background through the callback pipeline", () => {
 		const { terminal } = setupTerminal();
 		const appearances: string[] = [];