[LesleyMurfin]

ELI5

When reconnecting or re-attaching to a remote terminal session that has terminated or been reaped by the remote host daemon, the server returns terminal_not_found. Previously, the client's attachment logic surfaced an error message but never cleared its internal connecting = true flag. This left the UI in a permanent connecting state with an infinite loading spinner. This fix ensures that when terminal_not_found occurs during attach(), connecting is reset to false, the terminal is marked as ended, and recovery state is emitted so the UI unblocks and transitions cleanly.

What Changed

• remote-runtime-pty-transport.ts:
  • In attach(), when resolvePersistedHostPane() returns null (due to terminal_not_found), set connecting = false, terminalEnded = true, and call emitRecoveryState() prior to surfacing the error.
  • Added terminal_not_found to isRemoteTerminalGoneMessage() to ensure that asynchronous terminal absence tokens are treated as definitive lifecycle exits.
• remote-runtime-pty-transport-expired-pane-recovery.test.ts: Added a regression test verifying that encountering terminal_not_found during attach() immediately unblocks the connecting state and transitions the transport recovery phase to 'ended'.

Why

Without resetting connecting and transitioning to ended, getRecoveryState().phase permanently resolves to 'connecting'. As a result, the terminal surface is stuck behind an infinite loading spinner, retry buttons and manual recovery paths are disabled, and listeners are left dangling.

Linked Issue

Architectural Context (RFC #21556)

• Roadmap Phase: Step 3: Reconnect & Attach (Gap 6)
• Severity / Priority: P1 (High)
• Why It Ties into the Lifecycle: When re-attaching to a terminal that exited while disconnected, the remote daemon returns terminal_not_found. The client transport was swallowing this error and leaving connecting: true latched permanently.
• System Impact: Unblocks the client UI from an infinite loading spinner and immediately emits terminal ended/closed state so the reconciler can recover.
• Master Tracking RFC: Part of stablyai/orca#21556

Fixes #21344
Relates to #20922, #20923

Visual Proof

N/A - Transport state machine unblocking and lifecycle transition fix.

Testing

• I manually tested these changes locally
• Automated tests added/updated, or explained why not below

Ran vitest run --config config/vitest.config.ts src/renderer/src/components/terminal-pane/remote-runtime-pty-transport-expired-pane-recovery.test.ts:

• 6 tests passed.

AI Disclosure

Claude 3.5 Sonnet / Antigravity via Revive Labs development harness.

Checklist

• This PR is small and focused
• I explained what changed and why (ELI5, the user-facing before/after, the mechanism, and why over the alternatives)
• Before/after screenshots or videos attached for UI changes, or N/A with reason
• Self-reviewed for correctness, security, and performance
• Cross-platform, SSH/remote, and path/shortcut impact considered (or N/A)