diff --git a/src/features/tmux-subagent/manager.ts b/src/features/tmux-subagent/manager.ts
index f07f82c8b..3f9ca54e7 100644
--- a/src/features/tmux-subagent/manager.ts
+++ b/src/features/tmux-subagent/manager.ts
@@ -137,6 +137,7 @@ export class TmuxSessionManager {
       this.retryPendingCloses.bind(this),
       this.queryWindowStateSafely.bind(this),
       this.activateTrackedSessionPane.bind(this),
+      this.canAutoActivatePane.bind(this),
     )
     this.deps.log("[tmux-session-manager] initialized", {
       configEnabled: this.tmuxConfig.enabled,
@@ -385,6 +386,11 @@ export class TmuxSessionManager {
     return true
   }
 
+  private canAutoActivatePane(state: WindowState): boolean {
+    if (!this.isIsolated()) return true
+    return state.windowActive && state.sessionAttached
+  }
+
   private async closeTrackedSessionPane(args: {
     tracked: TrackedSession
     state: WindowState
diff --git a/src/features/tmux-subagent/pane-state-parser.test.ts b/src/features/tmux-subagent/pane-state-parser.test.ts
index 991c3fd95..87839203e 100644
--- a/src/features/tmux-subagent/pane-state-parser.test.ts
+++ b/src/features/tmux-subagent/pane-state-parser.test.ts
@@ -6,7 +6,7 @@ import { parsePaneStateOutput } from "./pane-state-parser"
 describe("parsePaneStateOutput", () => {
   it("rejects malformed integer fields", () => {
     // given
-    const stdout = "%0\t120oops\t40\t0\t0\t1\t120\t40\n"
+    const stdout = "%0\t120oops\t40\t0\t0\t1\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -17,7 +17,7 @@ describe("parsePaneStateOutput", () => {
 
   it("rejects negative integer fields", () => {
     // given
-    const stdout = "%0\t-1\t40\t0\t0\t1\t120\t40\n"
+    const stdout = "%0\t-1\t40\t0\t0\t1\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -28,7 +28,7 @@ describe("parsePaneStateOutput", () => {
 
   it("rejects empty integer fields", () => {
     // given
-    const stdout = "%0\t\t40\t0\t0\t1\t120\t40\n"
+    const stdout = "%0\t\t40\t0\t0\t1\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -39,7 +39,7 @@ describe("parsePaneStateOutput", () => {
 
   it("rejects non-binary active flags", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\tx\t120\t40\n"
+    const stdout = "%0\t120\t40\t0\t0\tx\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -50,7 +50,7 @@ describe("parsePaneStateOutput", () => {
 
   it("rejects numeric active flags other than zero or one", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\t2\t120\t40\n"
+    const stdout = "%0\t120\t40\t0\t0\t2\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -61,7 +61,18 @@ describe("parsePaneStateOutput", () => {
 
   it("rejects empty active flags", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\t\t120\t40\n"
+    const stdout = "%0\t120\t40\t0\t0\t\t120\t40\t1\t1\n"
+
+    // when
+    const result = parsePaneStateOutput(stdout)
+
+    // then
+    expect(result).toBe(null)
+  })
+
+  it("rejects malformed session attached field", () => {
+    // given
+    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\t1\tnope\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
diff --git a/src/features/tmux-subagent/pane-state-parser.ts b/src/features/tmux-subagent/pane-state-parser.ts
index 3ae6579d8..97e240ee2 100644
--- a/src/features/tmux-subagent/pane-state-parser.ts
+++ b/src/features/tmux-subagent/pane-state-parser.ts
@@ -1,10 +1,12 @@
 import type { TmuxPaneInfo } from "./types"
 
-const MANDATORY_PANE_FIELD_COUNT = 8
+const MANDATORY_PANE_FIELD_COUNT = 10
 
 type ParsedPaneState = {
   windowWidth: number
   windowHeight: number
+  windowActive: boolean
+  sessionAttached: boolean
   panes: TmuxPaneInfo[]
 }
 
@@ -12,6 +14,8 @@ type ParsedPaneLine = {
   pane: TmuxPaneInfo
   windowWidth: number
   windowHeight: number
+  windowActive: boolean
+  sessionAttached: boolean
 }
 
 type MandatoryPaneFields = [
@@ -23,6 +27,8 @@ type MandatoryPaneFields = [
   activeString: string,
   windowWidthString: string,
   windowHeightString: string,
+  windowActiveString: string,
+  sessionAttachedString: string,
 ]
 
 export function parsePaneStateOutput(stdout: string): ParsedPaneState | null {
@@ -45,6 +51,8 @@ export function parsePaneStateOutput(stdout: string): ParsedPaneState | null {
   return {
     windowWidth: latestPaneLine.windowWidth,
     windowHeight: latestPaneLine.windowHeight,
+    windowActive: latestPaneLine.windowActive,
+    sessionAttached: latestPaneLine.sessionAttached,
     panes: parsedPaneLines.map(({ pane }) => pane),
   }
 }
@@ -54,7 +62,7 @@ function parsePaneLine(line: string): ParsedPaneLine | null {
   const mandatoryFields = getMandatoryPaneFields(fields)
   if (!mandatoryFields) return null
 
-  const [paneId, widthString, heightString, leftString, topString, activeString, windowWidthString, windowHeightString] = mandatoryFields
+  const [paneId, widthString, heightString, leftString, topString, activeString, windowWidthString, windowHeightString, windowActiveString, sessionAttachedString] = mandatoryFields
 
   const width = parseInteger(widthString)
   const height = parseInteger(heightString)
@@ -63,6 +71,8 @@ function parsePaneLine(line: string): ParsedPaneLine | null {
   const isActive = parseActiveValue(activeString)
   const windowWidth = parseInteger(windowWidthString)
   const windowHeight = parseInteger(windowHeightString)
+  const windowActive = parseActiveValue(windowActiveString)
+  const sessionAttached = parseAttachedValue(sessionAttachedString)
 
   if (
     width === null ||
@@ -71,7 +81,9 @@ function parsePaneLine(line: string): ParsedPaneLine | null {
     top === null ||
     isActive === null ||
     windowWidth === null ||
-    windowHeight === null
+    windowHeight === null ||
+    windowActive === null ||
+    sessionAttached === null
   ) {
     return null
   }
@@ -88,13 +100,15 @@ function parsePaneLine(line: string): ParsedPaneLine | null {
     },
     windowWidth,
     windowHeight,
+    windowActive,
+    sessionAttached,
   }
 }
 
 function getMandatoryPaneFields(fields: string[]): MandatoryPaneFields | null {
   if (fields.length < MANDATORY_PANE_FIELD_COUNT) return null
 
-  const [paneId, widthString, heightString, leftString, topString, activeString, windowWidthString, windowHeightString] = fields
+  const [paneId, widthString, heightString, leftString, topString, activeString, windowWidthString, windowHeightString, windowActiveString, sessionAttachedString] = fields
 
   if (
     paneId === undefined ||
@@ -104,7 +118,9 @@ function getMandatoryPaneFields(fields: string[]): MandatoryPaneFields | null {
     topString === undefined ||
     activeString === undefined ||
     windowWidthString === undefined ||
-    windowHeightString === undefined
+    windowHeightString === undefined ||
+    windowActiveString === undefined ||
+    sessionAttachedString === undefined
   ) {
     return null
   }
@@ -118,6 +134,8 @@ function getMandatoryPaneFields(fields: string[]): MandatoryPaneFields | null {
     activeString,
     windowWidthString,
     windowHeightString,
+    windowActiveString,
+    sessionAttachedString,
   ]
 }
 
@@ -133,3 +151,8 @@ function parseActiveValue(value: string): boolean | null {
   if (value === "0") return false
   return null
 }
+
+function parseAttachedValue(value: string): boolean | null {
+  if (!/^\d+$/.test(value)) return null
+  return Number.parseInt(value, 10) > 0
+}
diff --git a/src/features/tmux-subagent/pane-state-querier.test.ts b/src/features/tmux-subagent/pane-state-querier.test.ts
index 708889246..da3a6a45c 100644
--- a/src/features/tmux-subagent/pane-state-querier.test.ts
+++ b/src/features/tmux-subagent/pane-state-querier.test.ts
@@ -6,7 +6,7 @@ import { parsePaneStateOutput } from "./pane-state-parser"
 describe("parsePaneStateOutput", () => {
   it("accepts a single pane when tmux omits the empty trailing title field", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\n"
+    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\t1\t1\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -16,6 +16,8 @@ describe("parsePaneStateOutput", () => {
     expect(result).toEqual({
       windowWidth: 120,
       windowHeight: 40,
+      windowActive: true,
+      sessionAttached: true,
       panes: [
         {
           paneId: "%0",
@@ -32,7 +34,7 @@ describe("parsePaneStateOutput", () => {
 
   it("handles CRLF line endings without dropping panes", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\r\n%1\t60\t40\t60\t0\t0\t120\t40\tagent\r\n"
+    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\t1\t1\r\n%1\t60\t40\t60\t0\t0\t120\t40\t1\t1\tagent\r\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
@@ -63,13 +65,15 @@ describe("parsePaneStateOutput", () => {
 
   it("preserves tabs inside pane titles", () => {
     // given
-    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\ttitle\twith\ttabs\n"
+    const stdout = "%0\t120\t40\t0\t0\t1\t120\t40\t0\t0\ttitle\twith\ttabs\n"
 
     // when
     const result = parsePaneStateOutput(stdout)
 
     // then
     expect(result).not.toBe(null)
+    expect(result?.windowActive).toBe(false)
+    expect(result?.sessionAttached).toBe(false)
     expect(result?.panes[0]?.title).toBe("title\twith\ttabs")
   })
 })
diff --git a/src/features/tmux-subagent/pane-state-querier.ts b/src/features/tmux-subagent/pane-state-querier.ts
index 3dfa911ef..1b0c1a104 100644
--- a/src/features/tmux-subagent/pane-state-querier.ts
+++ b/src/features/tmux-subagent/pane-state-querier.ts
@@ -19,7 +19,7 @@ export async function queryWindowStateWithDeps(sourcePaneId: string, deps: Query
     "-t",
     sourcePaneId,
     "-F",
-		"#{pane_id}\t#{pane_width}\t#{pane_height}\t#{pane_left}\t#{pane_top}\t#{pane_active}\t#{window_width}\t#{window_height}\t#{pane_title}",
+		"#{pane_id}\t#{pane_width}\t#{pane_height}\t#{pane_left}\t#{pane_top}\t#{pane_active}\t#{window_width}\t#{window_height}\t#{window_active}\t#{session_attached}\t#{pane_title}",
   ])
 
 	if (result.exitCode !== 0) {
@@ -38,6 +38,8 @@ export async function queryWindowStateWithDeps(sourcePaneId: string, deps: Query
   const { panes } = parsedPaneState
   const windowWidth = parsedPaneState.windowWidth
   const windowHeight = parsedPaneState.windowHeight
+  const windowActive = parsedPaneState.windowActive
+  const sessionAttached = parsedPaneState.sessionAttached
 
   panes.sort((a, b) => a.left - b.left || a.top - b.top)
 
@@ -71,7 +73,7 @@ export async function queryWindowStateWithDeps(sourcePaneId: string, deps: Query
     agentPaneCount: agentPanes.length,
   })
 
-  return { windowWidth, windowHeight, mainPane, agentPanes }
+  return { windowWidth, windowHeight, windowActive, sessionAttached, mainPane, agentPanes }
 }
 
 export async function queryWindowState(sourcePaneId: string): Promise<WindowState | null> {
diff --git a/src/features/tmux-subagent/polling-manager.test.ts b/src/features/tmux-subagent/polling-manager.test.ts
index 69526610c..f9dd28359 100644
--- a/src/features/tmux-subagent/polling-manager.test.ts
+++ b/src/features/tmux-subagent/polling-manager.test.ts
@@ -269,6 +269,8 @@ describe("TmuxPollingManager overlap", () => {
     const windowState: WindowState = {
       windowWidth: 160,
       windowHeight: 48,
+      windowActive: true,
+      sessionAttached: true,
       mainPane: null,
       agentPanes: [
         { paneId: "%1", width: 80, height: 24, left: 0, top: 0, title: "agent", isActive: true },
diff --git a/src/features/tmux-subagent/polling-manager.ts b/src/features/tmux-subagent/polling-manager.ts
index 9c457a20c..5d22297c1 100644
--- a/src/features/tmux-subagent/polling-manager.ts
+++ b/src/features/tmux-subagent/polling-manager.ts
@@ -24,6 +24,7 @@ export class TmuxPollingManager {
     private retryPendingCloses?: () => Promise<void>,
     private getWindowState?: () => Promise<WindowState | null>,
     private activateSessionPane?: (tracked: TrackedSession) => Promise<boolean>,
+    private canActivatePane: (state: WindowState) => boolean = (state) => state.windowActive !== false && state.sessionAttached !== false,
   ) {}
 
   handleEvent(event: { type: string; properties?: Record<string, unknown> }): void {
@@ -220,6 +221,13 @@ export class TmuxPollingManager {
 
     const state = await this.getWindowState().catch(() => null)
     if (!state) return
+    if (this.canActivatePane && !this.canActivatePane(state)) {
+      log("[tmux-session-manager] activation gate blocked auto-attach", {
+        windowActive: state.windowActive,
+        sessionAttached: state.sessionAttached,
+      })
+      return
+    }
 
     const panes = [state.mainPane, ...state.agentPanes].filter((pane): pane is NonNullable<typeof pane> => Boolean(pane))
     const activePaneIds = new Set(panes.filter((pane) => pane.isActive).map((pane) => pane.paneId))
diff --git a/src/features/tmux-subagent/types.ts b/src/features/tmux-subagent/types.ts
index 27567afa5..9d120088a 100644
--- a/src/features/tmux-subagent/types.ts
+++ b/src/features/tmux-subagent/types.ts
@@ -31,6 +31,8 @@ export interface TmuxPaneInfo {
 export interface WindowState {
   windowWidth: number
   windowHeight: number
+  windowActive?: boolean
+  sessionAttached?: boolean
   mainPane: TmuxPaneInfo | null
   agentPanes: TmuxPaneInfo[]
 }