02 / AI Root Cause Analysis

Root Cause Diagnosis & Reasoning

Interactive Demo
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What is Diagnosis? Rather than dumping raw error logs, Debug Vitals calculates the exact root cause behind your failure and explains it in plain English with supporting evidence.
Primary Root Cause Identified

Agent removed token validation in auth middleware during a performance refactor, causing all unauthenticated requests to return 200 instead of 401.

The agent was optimising request latency and removed the token verification block in AuthMiddleware as a temporary test. The change was committed and pushed. CI runs the security test suite which asserts that unauthenticated requests return 401 — all 8 tests now fail because every request returns 200.

97%
Confidence
Chronological Causal ChainHow the initial change propagated into a system failure
Agent Action
Agent action
Removed verify_token() call in auth.py
Failure
→
Code Change
Code change
AuthMiddleware skips token check
Failure
→
Environment
Auth bypass
All requests return 200 regardless of token
Failure
→
Test Result
8 tests failed
AssertionError: expected 401, got 200
Failure
→
CI Pipeline
CI build failed
job: test-security — conclusion: failure
Failure
Supporting Evidence & DataSpecific file changes and version logs proving this root cause
Removed line
app/middleware/auth.py
- if not token or not verify_token(token):
-     raise HTTPException(status_code=401)
Current code
app/middleware/auth.py
# FIXME: skipped for perf testing
pass
Failing assertion
tests/test_auth.py
AssertionError: assert 200 == 401
Git diff
git diff HEAD~1
@@ -14 +14 @@
-  raise HTTPException(status_code=401)
+  pass
Ranked Potential Root CausesTop 2 candidate causes weighted by evidence
#1
AuthMiddleware.__call__ no longer validates token — all requests pass through.
97% Probability
#2
JWT secret not rotated — old tokens still accepted if validation were re-enabled.
21% Probability
Affected System ComponentsFiles and services impacted by this issue
app/middleware/auth.py8 security testsAll authenticated routes
💡 Recommended Action

Revert the auth middleware change, or restore the verify_token() call before the pass statement.