Auto-create lane loading and error states break in new chat pane

[arul28]

Problem

When auto-create lane runs from the new chat pane, the small loading/model status UI is not polished or clear. If the user leaves the new chat pane while the auto-create flow is running, the flow appears to stop working or lose its visible state. If the flow errors, the error does not reliably show when the user returns to the new chat pane.

Expected

Auto-create lane should have a clear, stable loading state in the new chat pane. Leaving and returning to the pane should not lose progress, status, or errors. If the operation fails, the error should remain visible and actionable when the user comes back.

Actual

The loading/status UI feels rough, and navigation away from the new chat pane can make the operation appear broken. Errors can be lost or hidden after returning to the pane.

Areas to inspect

• New chat pane auto-create lane loading/status component.
• Whether auto-create lane state is owned by a mounted component instead of durable pane/session state.
• How errors are stored and restored after pane unmount/remount or navigation.
• Whether the loading/model indicator needs clearer copy, spacing, and failure affordances.

Acceptance criteria

• Auto-create lane shows a polished, understandable loading/status state.
• Navigating away from the new chat pane does not cancel or visually lose the running auto-create flow unless the user explicitly cancels it.
• Returning to the pane restores the current progress or final state.
• Errors remain visible after returning to the pane, with enough detail/action to retry or recover.

[linear-code]

ADE-96