refactor: remove unused constants and dead pollSessions from tmux-subagent

src/features/tmux-subagent/manager.ts

@@ -5,8 +5,6 @@ import { log, normalizeSDKResponse } from "../../shared"
 import {
   isInsideTmux as defaultIsInsideTmux,
   getCurrentPaneId as defaultGetCurrentPaneId,
-  POLL_INTERVAL_BACKGROUND_MS,
-  SESSION_MISSING_GRACE_MS,
   SESSION_READY_POLL_INTERVAL_MS,
   SESSION_READY_TIMEOUT_MS,
 } from "../../shared/tmux"
@@ -31,13 +29,6 @@ const defaultTmuxDeps: TmuxUtilDeps = {
   getCurrentPaneId: defaultGetCurrentPaneId,
 }
 
-const SESSION_TIMEOUT_MS = 10 * 60 * 1000
-
-// Stability detection constants (prevents premature closure - see issue #1330)
-// Mirrors the proven pattern from background-agent/manager.ts
-const MIN_STABILITY_TIME_MS = 10 * 1000  // Must run at least 10s before stability detection kicks in
-const STABLE_POLLS_REQUIRED = 3          // 3 consecutive idle polls (~6s with 2s poll interval)
-
 /**
  * State-first Tmux Session Manager
  * 
@@ -127,12 +118,6 @@ export class TmuxSessionManager {
     return false
   }
 
-  // NOTE: Exposed (via `as any`) for test stability checks.
-  // Actual polling is owned by TmuxPollingManager.
-  private async pollSessions(): Promise<void> {
-    await (this.pollingManager as any).pollSessions()
-  }
-
   async onSessionCreated(event: SessionCreatedEvent): Promise<void> {
     const enabled = this.isEnabled()
     log("[tmux-session-manager] onSessionCreated called", {

src/features/tmux-subagent/pane-split-availability.ts

@@ -1,4 +1,4 @@
-import { MIN_PANE_HEIGHT, MIN_PANE_WIDTH } from "./types"
+import { MIN_PANE_WIDTH } from "./types"
 import type { SplitDirection, TmuxPaneInfo } from "./types"
 import {
 	DIVIDER_SIZE,