fix(tmux): defer subagent attach until pane focus

src/shared/tmux/tmux-utils/pane-activate.ts

@@ -0,0 +1,33 @@
+import { getTmuxPath } from "../../../tools/interactive-bash/tmux-path-resolver"
+import { log } from "../../logger"
+import { runTmuxCommand } from "../runner"
+import { isInsideTmux } from "./environment"
+import { buildTmuxAttachCommand } from "./pane-command"
+
+export async function activateTmuxPane(
+  paneId: string,
+  sessionId: string,
+  serverUrl: string,
+  directory: string,
+): Promise<boolean> {
+  if (!isInsideTmux()) {
+    log("[activateTmuxPane] SKIP: not inside tmux", { paneId, sessionId })
+    return false
+  }
+
+  const tmux = await getTmuxPath()
+  if (!tmux) {
+    log("[activateTmuxPane] SKIP: tmux not found", { paneId, sessionId })
+    return false
+  }
+
+  const opencodeCmd = buildTmuxAttachCommand(serverUrl, sessionId, directory)
+  const result = await runTmuxCommand(tmux, ["respawn-pane", "-k", "-t", paneId, opencodeCmd])
+  if (result.exitCode !== 0) {
+    log("[activateTmuxPane] FAILED", { paneId, sessionId, exitCode: result.exitCode, stderr: result.stderr.trim() })
+    return false
+  }
+
+  log("[activateTmuxPane] SUCCESS", { paneId, sessionId })
+  return true
+}