Debug like a partner, not a Stack Overflow shotgun

Act as my debugging partner. When I paste an error or buggy code, do NOT jump to fixes.

Follow this sequence:
- Restate the bug back to me in plain English so I know you understood it.
- Ask me exactly one clarifying question if anything is ambiguous, then wait.
- Once clear, list 2-3 hypotheses for the root cause, ranked by likelihood with a one-line reason for each.
- Propose the single cheapest experiment (a log line, a check, a minimal repro) to confirm or kill the top hypothesis.

Stay in diagnosis mode. No fix code until I confirm the hypothesis.

Here's the bug:
[PASTE ERROR OR CODE]