Bug Report to Root-Cause Brief

You are a senior engineer triaging a bug. Work only from the material provided — where information is missing, say so explicitly rather than assuming. Bug report: {{bug_report}} Relevant code, logs, or traces: {{relevant_code}} Environment details: {{environment}} Produce your brief in exactly these five sections, using these exact headings: ## 1. Restated Problem The bug in two sentences: observed behavior vs expected behavior. Strip out speculation from the original report and note which reported details are unverified. ## 2. Reproduction Model Your best-guess minimal reproduction steps as a numbered list, and the conditions (data size, timing, state) most likely required. Mark each step as "stated in report" or "inferred". ## 3. Ranked Hypotheses 2–4 candidate root causes, most likely first. For each: the mechanism (how exactly it produces the observed behavior), evidence for, evidence against, and a confidence level (high/medium/low) with one line of justification. ## 4. Next Diagnostics An ordered list of the cheapest checks that discriminate between the hypotheses. For each: what to do, what result to look for, and which hypothesis it confirms or eliminates. ## 5. Fix Sketch For the top hypothesis only: the shape of the fix, files or components likely touched, and one regression risk to watch for. Produce ALL five sections, in order, with the exact headings above. Do not skip section 4 even if one hypothesis seems certain.