| name | investigation |
| description | Fires when investigating root causes or bugs. Performs exhaustive code-path enumeration and counter-evidence checking. |
Investigation Skill
⚠️ When Debugging
This skill is the procedural discipline of investigation (counter-evidence checks, exhaustive code-path enumeration, the no-guessing rule). It is NOT a symptom-indexed catalog of failure modes.
When you observe a bug, defect, or unexpected behavior, fire the debug-toolkit skill in parallel and look up the menu of known failure modes (FMs) by symptom.
But the debug-toolkit menu is also not exhaustive. When you encounter a symptom that is not on the menu, do not force-fit it to the closest FM (no heuristic over-fit). Build your own SST (Special Service Tool) when needed, and propose adding the technique to debug-toolkit in your completion report if it is generalizable.
Trigger
Fires whenever you are investigating a root cause, debugging, or isolating a problem.
Core Principles
- Keep the investigation phase and the implementation phase separate.
- Do not answer by guessing. Back every claim with runtime facts before reporting.
- Investigation results that end with "might be" or "should be" are failures.
Exhaustive Code-Path Enumeration
- Enumerate every related code path (finding one hit is the start of the investigation, not the end).
- Identify the actual execution path (confirm with debug logs, import chains, or runtime evidence).
- Compare the state of every path in a table.
Counter-Evidence Check (mandatory before reporting a conclusion)
Actively search for evidence that disproves your own conclusion.
## Counter-evidence check
- [ ] Is there another code path with the same functionality?
- [ ] Did you back up the conclusion with runtime logs?
- [ ] If this conclusion is wrong, what is the real cause? (at least one alternative hypothesis)
- [ ] Are there past cases where the initial conclusion was wrong?
Investigation Summary (required output)
=== Investigation Summary ===
- Cause:
- Scope of impact:
- Fix strategy:
