debugginglisted

# Debugging The goal is the *cause*, not the symptom's disappearance. A fix applied without understanding is a second bug waiting. ## Method 1. **Reproduce before anything else.** Get the exact failing input, command, or click path, and confirm you can trigger the failure on demand. A bug you cannot reproduce is a bug you cannot verify fixed. If reproduction is impossible, gather the evidence you do have (logs, stack trace, timing) and say plainly that the fix will be a hypothesis. 2. **State the symptom precisely.** "Fails" is not a symptom. "Returns 200 with an empty list when the user has 3 orders" is. Write down expected vs actual; the gap between them is the search space. 3. **Form one falsifiable hypothesis.** "The cache returns stale data because the key omits the user id": specific enough that an experiment can kill it. If you have three hypotheses, rank by likelihood and cheapest test first. 4. **Run the smallest experiment that can falsify it.** Read the code path, add one log line, write a one-case test, bisect the commit range, or shrink the failing input by halves. One variable per experiment; change two things and you have learned nothing. 5. **Loop.** Each dead hypothesis narrows the space. When an experiment confirms the cause, you should be able to explain the entire chain: trigger → mechanism → observed symptom. If any link is fuzzy, keep going. 6. **Fix the cause, then prove it.** The reproduction from step 1 mus