fix: cleanup attach windows when removing jobs

Tag tmux windows created by mc_attach with @mc_job_id so mc_cleanup
can find and close them. Previously attach windows were orphaned after
cleanup, requiring manual removal.

Author: nigel-dev

src/lib/tmux.ts

@@ -116,6 +116,58 @@ export async function createWindow(opts: {
   }
 }
 
+/**
+ * Set a user option on a tmux window for ownership tracking
+ */
+export async function setWindowOption(target: string, option: string, value: string): Promise<void> {
+  try {
+    const proc = spawn(["tmux", "set-option", "-w", "-t", target, option, value], { stderr: "pipe" });
+    const exitCode = await proc.exited;
+    if (exitCode !== 0) {
+      throw new Error(`tmux set-option failed with exit code ${exitCode}`);
+    }
+  } catch (error) {
+    throw new Error(
+      `Failed to set tmux window option: ${error instanceof Error ? error.message : String(error)}`
+    );
+  }
+}
+
+/**
+ * Find and kill all tmux windows tagged with a specific job ID
+ */
+export async function killTaggedWindows(jobId: string): Promise<number> {
+  try {
+    const proc = spawn(
+      ["tmux", "list-windows", "-a", "-F", "#{session_name}:#{window_index} #{@mc_job_id}"],
+      { stderr: "pipe" },
+    );
+    const output = await new Response(proc.stdout).text();
+    const exitCode = await proc.exited;
+    if (exitCode !== 0) {
+      return 0;
+    }
+
+    let killed = 0;
+    for (const line of output.trim().split('\n')) {
+      if (!line.trim()) continue;
+      const [target, taggedId] = line.split(' ', 2);
+      if (taggedId === jobId && target) {
+        try {
+          const killProc = spawn(["tmux", "kill-window", "-t", target], { stderr: "pipe" });
+          await killProc.exited;
+          killed++;
+        } catch {
+          // Best-effort: window may already be gone
+        }
+      }
+    }
+    return killed;
+  } catch {
+    return 0;
+  }
+}
+
 /**
  * Check if a tmux session exists
  */

src/tools/attach.ts

@@ -1,6 +1,6 @@
 import { tool, type ToolDefinition } from '@opencode-ai/plugin';
 import { getJobByName } from '../lib/job-state';
-import { isInsideTmux, createWindow, getCurrentSession } from '../lib/tmux';
+import { isInsideTmux, createWindow, getCurrentSession, setWindowOption } from '../lib/tmux';
 
 export const mc_attach: ToolDefinition = tool({
   description: 'Get instructions for attaching to a job\'s terminal',
@@ -37,6 +37,12 @@ export const mc_attach: ToolDefinition = tool({
           command: attachCommand,
         });
 
+        try {
+          await setWindowOption(`${currentSession}:${windowName}`, '@mc_job_id', job.id);
+        } catch {
+          // Best-effort: tagging failure should not block attach
+        }
+
         return `Opened TUI for job '${job.name}' in new tmux window`;
       } else {
         // Not inside tmux, return the command to run

src/tools/cleanup.ts

@@ -1,7 +1,7 @@
 import { tool, type ToolDefinition } from '@opencode-ai/plugin';
 import { getJobByName, removeJob, getRunningJobs, loadJobState } from '../lib/job-state';
 import { removeWorktree } from '../lib/worktree';
-import { killSession, sessionExists } from '../lib/tmux';
+import { killSession, sessionExists, killTaggedWindows } from '../lib/tmux';
 import { gitCommand } from '../lib/git';
 import { removeReport } from '../lib/reports';
 import { releasePort } from '../lib/port-allocator';
@@ -59,6 +59,8 @@ async function cleanupJobs(
         try { await killSession(job.tmuxTarget); } catch {}
       }
 
+      try { await killTaggedWindows(job.id); } catch {}
+
       if (job.port) {
         try { await releasePort(job.port); } catch {}
       }