Fix a bug in code you did not write

1 to 2 hours · 7 steps

It is easy to get an agent to patch a symptom in code nobody in the conversation understands. This route makes understanding the first step and ends by making the mistake harder to repeat.

Before you start

• A reproducible bug, or at least a report of one
• The addy, pocock and pstack plugins installed
• New to the hub? Install the plugins first.

1. 1

   Understand the area first

   /pstack:how

   A walkthrough of the subsystem and its runtime flow, before anything changes.

   /pstack:how does the code around this bug work? <describe the bug> Copy

   Done when: You could explain the normal path through this code to someone else.

2. 2

   Diagnose it

   /pocock:diagnosing-bugs

   A diagnosis loop for hard bugs and performance regressions, in place of guessing at fixes until one sticks.

   /pocock:diagnosing-bugs <the symptom and how to reproduce it> Copy

   Done when: You have a root cause backed by evidence, not just a plausible story.

3. 3

   Find out why it is like this

   /pstack:why

   Checks history and whatever evidence sources are connected. Odd code is sometimes odd on purpose, and it is better to learn that before "fixing" it.

   /pstack:why does this code behave this way? Copy

   Done when: You know whether the behavior was a deliberate choice or an accident.

4. 4

   Pin the bug with a failing test

   /addy:test-driven-development

   The test has to fail first. That proves it catches this bug and keeps it from coming back.

   /addy:test-driven-development Write a failing test for this bug, then fix it. Copy

   Done when: The test failed before the fix and passes after it.

5. 5

   Check nothing else moved

   /pstack:blast-radius

   Small fixes in unfamiliar code can break things far away. This is the one to run when you do not fully trust a small diff.

   /pstack:blast-radius of this fix Copy

   Done when: Other callers of the changed code are accounted for.

6. 6

   Review before merging

   /addy:code-review-and-quality

   A multi-axis review, useful here because whoever wrote the fix, human or agent, is the least likely to notice what they assumed.

   /addy:code-review-and-quality Review this fix. Copy

   Done when: Findings are fixed or consciously accepted.

7. 7

   Make the mistake impossible

   /pstack:correct

   Only for mistakes agents keep repeating here. It tries architecture, then types, then a lint, then a test, with docs last, and proves each check fails on a real past mistake.

   /pstack:correct Copy

   Done when: The check fails on the old mistake. Skip this step for a true one-off.

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