From f69e8b5c3e56faf313448aff5f41220ee1056386 Mon Sep 17 00:00:00 2001
From: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>
Date: Sun, 16 Aug 2026 19:38:02 -0700
Subject: [PATCH] fix(agent-teams): replace panes only after confirmed stop

---
 .../claude-agent-teams-service.test.ts        | 15 +++----
 .../claude-agent-teams-tmux-dispatcher.ts     | 40 +++++++++----------
 2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/src/main/runtime/claude-agent-teams-service.test.ts b/src/main/runtime/claude-agent-teams-service.test.ts
index cf370e3d687..57f867cb1c2 100644
--- a/src/main/runtime/claude-agent-teams-service.test.ts
+++ b/src/main/runtime/claude-agent-teams-service.test.ts
@@ -189,7 +189,7 @@ describe('ClaudeAgentTeamsService', () => {
     expect(api.closeTerminal).toHaveBeenLastCalledWith('teammate-2')
   })
 
-  it('keeps the placeholder handle when the respawn split fails', async () => {
+  it('removes the pane when replacement split fails after a confirmed placeholder stop', async () => {
     const { service, teamId, token, leaderPane, api } = createServiceWithLeader()
     const request = (argv: string[], envPane = leaderPane) =>
       service.handleTmuxCompat({ teamId, token, envPane, argv }, api)
@@ -212,10 +212,10 @@ describe('ClaudeAgentTeamsService', () => {
       request(['respawn-pane', '-k', '-t', '%2', '--', 'claude --agent-id a'])
     ).resolves.toMatchObject({ ok: false, exitCode: 1 })
 
-    // the placeholder terminal is left intact and the fake pane id still resolves.
-    expect(api.closeTerminal).not.toHaveBeenCalled()
-    await request(['kill-pane', '-t', '%2'])
     expect(api.closeTerminal).toHaveBeenCalledWith('teammate-1')
+    await expect(
+      request(['list-panes', '-t', 'orca:0', '-F', '#{pane_id}'])
+    ).resolves.toMatchObject({ stdout: '%1\n' })
   })
 
   it('keeps a pane registered when its process stop is unconfirmed', async () => {
@@ -239,7 +239,7 @@ describe('ClaudeAgentTeamsService', () => {
     ).resolves.toMatchObject({ stdout: '%1\n%2\n' })
   })
 
-  it('keeps the replacement addressable when the retired placeholder stop is unconfirmed', async () => {
+  it('does not launch a replacement when the placeholder stop is unconfirmed', async () => {
     const { service, teamId, token, leaderPane, api, splitCalls } = createServiceWithLeader()
     const request = (argv: string[], envPane = leaderPane) =>
       service.handleTmuxCompat({ teamId, token, envPane, argv }, api)
@@ -256,14 +256,15 @@ describe('ClaudeAgentTeamsService', () => {
       request(['respawn-pane', '-k', '-t', '%2', '--', 'claude --agent-id a'])
     ).resolves.toMatchObject({ ok: false, exitCode: 1 })
     expect(api.closeTerminal).toHaveBeenNthCalledWith(1, 'teammate-1')
+    expect(splitCalls).toHaveLength(1)
 
     await expect(
       request(['respawn-pane', '-k', '-t', '%2', '--', 'claude --agent-id a'])
     ).resolves.toMatchObject({ ok: false, exitCode: 1 })
-    expect(splitCalls).toHaveLength(2)
+    expect(splitCalls).toHaveLength(1)
 
     await request(['kill-pane', '-t', '%2'])
-    expect(api.closeTerminal).toHaveBeenLastCalledWith('teammate-2')
+    expect(api.closeTerminal).toHaveBeenLastCalledWith('teammate-1')
   })
 
   it('refuses to respawn the leader pane', async () => {
diff --git a/src/main/runtime/claude-agent-teams-tmux-dispatcher.ts b/src/main/runtime/claude-agent-teams-tmux-dispatcher.ts
index 37f43ef9bcc..a9a3b4484a8 100644
--- a/src/main/runtime/claude-agent-teams-tmux-dispatcher.ts
+++ b/src/main/runtime/claude-agent-teams-tmux-dispatcher.ts
@@ -164,31 +164,25 @@ export class ClaudeAgentTeamsTmuxDispatcher {
     const origin =
       (pane.splitFromPane ? team.panes.get(pane.splitFromPane) : undefined) ??
       team.panes.get(team.leaderPane)!
-    // Why: create the replacement before destroying the placeholder so a failed
-    // split leaves the fake pane id pointing at a still-live terminal; on cleanup
-    // failure, discard the new split and keep the placeholder registered.
     const previousHandle = pane.handle
-    const split = await api.splitTerminal(origin.handle, {
-      direction: pane.splitDirection ?? 'horizontal',
-      command,
-      env: paneEnv(team, pane.fakePaneId),
-      envToDelete: ['TERM_PROGRAM'],
-      activate: false
-    })
+    const close = await api.closeTerminal(previousHandle)
+    if (!close.ptyKilled) {
+      pane.respawnBlockedReason = describeUnconfirmedAgentStop(close)
+      throw new Error(pane.respawnBlockedReason)
+    }
     try {
-      const close = await api.closeTerminal(previousHandle)
-      if (!close.ptyKilled) {
-        pane.handle = split.handle
-        pane.respawnBlockedReason = describeUnconfirmedAgentStop(close)
-        throw new Error(pane.respawnBlockedReason)
-      }
+      const split = await api.splitTerminal(origin.handle, {
+        direction: pane.splitDirection ?? 'horizontal',
+        command,
+        env: paneEnv(team, pane.fakePaneId),
+        envToDelete: ['TERM_PROGRAM'],
+        activate: false
+      })
+      pane.handle = split.handle
     } catch (error) {
-      if (pane.handle === previousHandle) {
-        await api.closeTerminal(split.handle).catch(() => {})
-      }
+      this.removePane(team, pane)
       throw error
     }
-    pane.handle = split.handle
     return ''
   }
 
@@ -281,13 +275,17 @@ export class ClaudeAgentTeamsTmuxDispatcher {
     if (!close.ptyKilled) {
       throw new Error(describeUnconfirmedAgentStop(close))
     }
+    this.removePane(team, pane)
+    return ''
+  }
+
+  private removePane(team: AgentTeam, pane: TeamPane): void {
     team.panes.delete(pane.fakePaneId)
     team.paneOrder = team.paneOrder.filter((id) => id !== pane.fakePaneId)
     if (team.mainVertical?.lastColumnPane === pane.fakePaneId) {
       team.mainVertical.lastColumnPane =
         [...team.paneOrder].toReversed().find((id) => id !== team.leaderPane) ?? null
     }
-    return ''
   }
 
   private async lastPane(