fix(ssh): make the partition hoist consume its source

A migration that leaves its source on disk runs again every launch, and its
hoist condition is 'local has no such tab' — which is exactly the state after
the user closes one. Closed panes came back on the next launch.

Deleting the partition once hoisted also completes the consolidation: local is
now the single plane for SSH pane membership, which is what the reattach binder
and the lease arbitration were already assuming.

Mutation-proofed: leaving the source behind reddens the new no-resurrection
test and nothing else.

src/main/persistence.ts

@@ -2913,6 +2913,15 @@ export function hoistSshPartitionsIntoLocalSession(
       local.activeTabIdByWorktree = { ...local.activeTabIdByWorktree, [worktreeId]: tabId }
       changed = true
     }
+    // Consume the source. A migration that leaves it behind runs again every launch and
+    // resurrects panes the user has since closed, because "local has no such tab" is exactly
+    // what this function treats as "needs hoisting".
+    if (state.workspaceSessionsByHostId?.[hostId]) {
+      const remaining = { ...state.workspaceSessionsByHostId }
+      delete remaining[hostId]
+      state.workspaceSessionsByHostId = remaining
+      changed = true
+    }
   }
   return changed
 }

src/main/ssh-partition-upgrade-tab-loss.test.ts

@@ -157,4 +157,28 @@ describe('an SSH pane whose membership was persisted into the ssh partition', ()
     expect(changed, 'the function reported no change').toBe(true)
     expect(state.workspaceSession?.tabsByWorktree?.[WORKTREE] ?? []).toHaveLength(1)
   })
+
+  // A migration that leaves its source behind runs again on the next launch and re-adds panes the
+  // user has since closed, because "local has no such tab" is precisely its hoist condition.
+  it('does not resurrect a tab the user closed after upgrading', async () => {
+    const before = await createStore()
+    before.setWorkspaceSession(paneSession() as never, SSH_PARTITION)
+    before.flushOrThrow()
+
+    // The upgrade launch hoists the pane.
+    const upgraded = await reopenStore()
+    expect(upgraded.getWorkspaceSession().tabsByWorktree?.[WORKTREE] ?? []).toHaveLength(1)
+
+    // The user closes it, and that sticks.
+    upgraded.setWorkspaceSession(
+      { ...upgraded.getWorkspaceSession(), tabsByWorktree: { [WORKTREE]: [] } } as never
+    )
+    upgraded.flushOrThrow()
+
+    const relaunched = await reopenStore()
+    expect(
+      relaunched.getWorkspaceSession().tabsByWorktree?.[WORKTREE] ?? [],
+      'the migration re-added a tab the user had closed'
+    ).toHaveLength(0)
+  })
 })