systematic-debugging

name	systematic-debugging
description	Repo-local root-cause debugging workflow for Zoolanding Lambda issues. Use before fixing handler validation bugs, contract mismatches, helper failures, packaging issues, or unexpected SAM behavior.
user-invocable	true

Systematic Debugging

No fixes without root-cause investigation.

Primary Targets In This Repo

• request parsing and validation
• storage or payload contract mismatches
• helper logic or dependency packaging failures
• SAM template, env var, or deployment wiring issues

Workflow

1. Reproduce the failure.

   • Capture the exact event, command, or request that fails.
   • Save the observable symptom: handler output, stack trace, failing assertion, or deployment error.

2. Localize the failing surface.

   • Decide whether the first bad state is in handler logic, a helper, dependency packaging, input shape, or template wiring.
   • Reduce the failure to the smallest reproducible event or command.

3. Trace to the first wrong state.

   • Follow data flow from the symptom back to the first incorrect assumption, payload field, env var, storage decision, or packaging step.
   • Prefer code evidence over intuition.

4. Fix the root cause.

   • Apply the smallest change that corrects the first wrong state.
   • Avoid defensive edits until the root cause is understood.

5. Verify the fix.

   • Re-run the failing command, event, or test.
   • Run the smallest adjacent regression check that would catch the same class of failure.

When You Are Stuck

• Add short-lived diagnostics at handler and storage boundaries.
• Build a minimal event fixture that isolates the contract edge.
• Compare code, README, and template assumptions instead of assuming they still match.