diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index 0bc5ffc5a..ab7d108e0 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -11,6 +11,7 @@
 ### Fixed
 
 - Fixed SIXEL image rendering stripping a horizontal slice from images when the cell height was not a multiple of 6. SIXEL encodes in 6-pixel vertical bands; a non-multiple-of-6 height was padded, causing the terminal to allocate an extra row that the TUI did not reserve — the next line of content then overwrote the bottom of the image. The encode height is now rounded down to the largest multiple of 6 within the requested row budget, eliminating padding without exceeding the caller's height cap, and the width is scaled by the same ratio to preserve the image aspect ratio.
+- Fixed the Kitty OSC 99 desktop-notification capability probe (`p=?`) firing under tmux/screen, where the multiplexer forwards the passthrough query to the outer terminal but cannot route the reply back to the sending pane — the capability list leaked into the pane as text and its bytes switched panes ([#5582](https://github.com/can1357/oh-my-pi/issues/5582)). The probe is now suppressed inside a multiplexer (rich notifications fall back to the single-line OSC 99 form until confirmed), mirroring the graphics-probe fix in #5381.
 
 ## [16.5.2] - 2026-07-14
 
diff --git a/packages/tui/src/terminal.ts b/packages/tui/src/terminal.ts
index 2ad11d612..695757cb9 100644
--- a/packages/tui/src/terminal.ts
+++ b/packages/tui/src/terminal.ts
@@ -12,12 +12,12 @@ import {
 import { setKittyProtocolActive } from "./keys";
 import { StdinBuffer } from "./stdin-buffer";
 import {
+	isInsideTerminalMultiplexer,
 	isInsideTmux,
 	NotifyProtocol,
 	setCellDimensions,
 	setOsc99Supported,
 	TERMINAL,
-	wrapTmuxPassthrough,
 } from "./terminal-capabilities";
 import { type HangulCompatibilityJamoWidth, setHangulCompatibilityJamoWidth } from "./utils";
 
@@ -1042,6 +1042,15 @@ export class ProcessTerminal implements Terminal {
 
 	#shouldQueryOsc99Support(): boolean {
 		if (TERMINAL.notifyProtocol !== NotifyProtocol.Osc99) return false;
+		// Never probe inside a terminal multiplexer. tmux/screen forward the
+		// passthrough-wrapped `p=?` query to the outer terminal, but cannot route
+		// the capability reply back to the pane that sent it (tmux/tmux#4386,
+		// tmux/tmux#3964), so the reply leaks into the pane as literal text and
+		// its bytes perturb input (issue #5582 — the notification sibling of the
+		// graphics-probe leak #5381). Rich notifications fall back to the
+		// single-line OSC 99 form until confirmation, and delivery still uses the
+		// passthrough/BEL path (#3395).
+		if (isInsideTerminalMultiplexer($env)) return false;
 		return !isBunTestRuntime() || $env.PI_TUI_OSC99_PROBE === "1";
 	}
 
@@ -1055,14 +1064,9 @@ export class ProcessTerminal implements Terminal {
 		const id = `omp-probe-${nextOsc99ProbeId++}`;
 		this.#osc99PendingId = id;
 		this.#da1SentinelOwners.push({ kind: "osc99Probe", id });
-		// Wrap the probe under tmux so terminals behind `allow-passthrough on`
-		// can still respond (mirroring how `TerminalInfo.sendNotification`
-		// wraps notification deliveries). Without it the probe is swallowed
-		// inside tmux even when the outer terminal speaks OSC 99, and rich
-		// notifications stay permanently downgraded to the single-line fallback.
-		const probe = `\x1b]99;i=${id}:p=?;\x1b\\`;
-		const sequence = isInsideTmux() ? wrapTmuxPassthrough(probe) : probe;
-		this.#safeWrite(`${sequence}\x1b[c`);
+		// The probe never runs under a multiplexer (see #shouldQueryOsc99Support),
+		// so it is always sent directly to the terminal.
+		this.#safeWrite(`\x1b]99;i=${id}:p=?;\x1b\\\x1b[c`);
 	}
 
 	#handleOsc99CapabilityResponse(metaRaw: string, payload: string): boolean {
diff --git a/packages/tui/test/notifications.test.ts b/packages/tui/test/notifications.test.ts
index 2c5245445..b6da7151b 100644
--- a/packages/tui/test/notifications.test.ts
+++ b/packages/tui/test/notifications.test.ts
@@ -291,16 +291,18 @@ describe("terminal notifications", () => {
 		expect(writes).toEqual(["\x1b]99;;ping\x1b\\\x07"]);
 	});
 
-	it("under tmux, the OSC 99 capability probe is wrapped in DCS passthrough", () => {
+	it("under tmux, the OSC 99 capability probe is suppressed (reply cannot route back to the pane)", () => {
 		Bun.env.PI_TUI_OSC99_PROBE = "1";
 		Bun.env.TMUX = "/tmp/tmux-1000/default,1234,0";
 		mutableTerminal.notifyProtocol = NotifyProtocol.Osc99;
 		const { terminal, writes } = setupProcessTerminal();
 		try {
-			const probe = writes.find(
-				w => w.startsWith("\x1bPtmux;\x1b\x1b]99;i=omp-probe-") && w.endsWith("\x1b\x1b\\\x1b\\\x1b[c"),
-			);
-			expect(probe).toBeDefined();
+			// tmux forwards the passthrough probe to the outer terminal but cannot
+			// route the `p=?` reply back to the sending pane, so the reply would
+			// leak into the pane as text (#5582). The probe must not fire at all.
+			const probe = writes.find(w => w.includes("]99;i=omp-probe-") && w.includes(":p=?"));
+			expect(probe).toBeUndefined();
+			expect(isOsc99Supported()).toBe(false);
 		} finally {
 			terminal.stop();
 		}