Code Consistency Checker

Scan Python files for logging issues. Flag incorrect severity levels and missing exception context.

Logging Level Decision Tree

Ask: What happened in this code?

code

Variable value, loop iteration, function entry/exit, detailed diagnostics?
  → DEBUG

Successful operation, workflow step completed, state change confirmed?
  → INFO

Unexpected but handled: fallback used, retry attempt, deprecated call, approaching limit?
  → WARNING

Functionality failed: operation error, caught exception, feature broken?
  → ERROR (use logger.exception() in except blocks)

System-wide failure: cannot serve requests, out of resources, imminent crash?
  → CRITICAL

Common Logging Mistakes

Wrong Severity Level

python

# ❌ WRONG: Exception logged as INFO
try:
    result = risky_operation()
except Exception as e:
    logger.info(f"Operation failed: {e}")  # Should be ERROR

# ✅ CORRECT: Use logger.exception() in except blocks
try:
    result = risky_operation()
except Exception as e:
    logger.exception("Operation failed")  # Automatically ERROR + stack trace

python

# ❌ WRONG: Normal operation logged as ERROR
user = get_user(user_id)
logger.error(f"Retrieved user {user_id}")  # Should be INFO or DEBUG

# ✅ CORRECT: Normal operations are INFO
user = get_user(user_id)
logger.info(f"Retrieved user {user_id}")

python

# ❌ WRONG: Fallback behavior logged as ERROR
cache_value = cache.get(key)
if cache_value is None:
    logger.error("Cache miss, using database")  # Should be WARNING or INFO
    value = db.query(key)

# ✅ CORRECT: Degraded mode is WARNING
cache_value = cache.get(key)
if cache_value is None:
    logger.warning("Cache miss, falling back to database")
    value = db.query(key)

python

# ❌ WRONG: Routine error logged as CRITICAL
if not user_id:
    logger.critical("Missing user_id parameter")  # Should be ERROR
    raise ValueError("user_id required")

# ✅ CORRECT: CRITICAL only for system-wide failures
if connection_pool_exhausted():
    logger.critical("Database connection pool exhausted, cannot serve requests")
    shutdown()

Missing Exception Context

python

# ❌ WRONG: Missing stack trace
try:
    process_data()
except Exception as e:
    logger.error(f"Failed: {e}")  # No stack trace

# ✅ CORRECT: Use logger.exception() or exc_info=True
try:
    process_data()
except Exception as e:
    logger.exception("Data processing failed")  # Includes stack trace

# ✅ ALSO CORRECT: Explicit exc_info
try:
    process_data()
except Exception as e:
    logger.error("Data processing failed", exc_info=True)

Logger Pattern Violations

python

# ❌ WRONG: Using root logger
logger = logging.getLogger()
logger.info("message")

# ✅ CORRECT: Named logger
logger = logging.getLogger(__name__)
logger.info("message")

python

# ❌ WRONG: Using print() for logging
print(f"Processing user {user_id}")

# ✅ CORRECT: Use logger
logger.info(f"Processing user {user_id}")

Security Issues

python

# ❌ WRONG: Logging sensitive data
logger.info(f"User authenticated: {username} / {password}")
logger.debug(f"API request: {api_key}")

# ✅ CORRECT: Redact sensitive information
logger.info(f"User authenticated: {username}")
logger.debug("API request authenticated")

Severity Level Guidelines

DEBUG (Development only, filter out in production)

•Variable values during execution
•Function entry/exit traces
•Loop iteration details
•Cache hits/misses (when debugging)
•Query performance timing
•Internal state inspection

Production: Set level to INFO or higher

INFO (Normal operations)

•User logged in/out
•Batch processing started/completed
•Configuration loaded
•Service started/stopped
•Scheduled job executed
•Workflow step completed
•Major operation succeeded

If it's expected and good, it's INFO

WARNING (Unexpected but handled)

•API rate limit approaching (80% capacity)
•Deprecated function called
•Retry attempt (N of M)
•Using fallback/default value
•Resource usage high but manageable
•Temporary degradation

If it's weird but working, it's WARNING

ERROR (Functionality failed)

•Database query failed
•API call failed
•File not found
•Validation error
•Tool execution failed
•User operation failed
•Any caught exception affecting functionality

Use logger.exception() in except blocks

CRITICAL (System failure)

•Database unreachable
•Out of memory
•Connection pool exhausted
•Authentication system down
•Cannot serve requests
•Imminent shutdown

Should trigger immediate alerts/paging

Check Execution

•
Find all logger calls: logger.debug/info/warning/error/critical/exception()
•
For each call, ask:
- •What situation triggered this log?
- •Does severity match the decision tree?
- •Is this in an except block? (should use logger.exception())
•
Check patterns:
- •Named logger used? (getLogger(__name__))
- •No print() statements for operational logging?
- •No sensitive data logged?
•
Flag issues with:
- •Line number
- •Current severity vs. correct severity
- •Reason for change

Output Format

code

FILE: path/to/file.py

LOGGING ISSUES:

Line 23: Severity too high
  Current: logger.error("Retrieved user data")
  Should be: logger.info("Retrieved user data")
  Reason: Normal successful operation should be INFO, not ERROR

Line 78: Missing exception context
  Current: logger.error(f"Failed: {e}")
  Should be: logger.exception("Operation failed")
  Reason: Use logger.exception() in except blocks for automatic stack trace

Line 134: Severity too low
  Current: logger.info("API call failed, retrying")
  Should be: logger.warning("API call failed, retrying")
  Reason: Retry indicates unexpected issue, should be WARNING

Line 201: Security violation
  Current: logger.debug(f"Authenticating with token: {api_token}")
  Should be: logger.debug("Authenticating with API")
  Reason: Never log credentials, tokens, or passwords

Line 234: Wrong logger pattern
  Current: logger = logging.getLogger()
  Should be: logger = logging.getLogger(__name__)
  Reason: Use named logger, not root logger

Line 289: Should use logger instead of print
  Current: print(f"Processing {count} items")
  Should be: logger.info(f"Processing {count} items")
  Reason: Use logging module for operational messages

SUMMARY: 6 logging issues found

Quick Reference Card

Situation	Level	Example
Loop iteration details	DEBUG	`logger.debug(f"Processing item {i} of {total}")`
Successful operation	INFO	`logger.info("Memory consolidation completed")`
Fallback/retry	WARNING	`logger.warning("Cache miss, using database")`
Operation failed	ERROR	`logger.exception("Failed to process data")`
System cannot function	CRITICAL	`logger.critical("Database unreachable")`

In except blocks: Always use logger.exception() or logger.error(..., exc_info=True)

Named logger: Always logger = logging.getLogger(__name__)

Security: Never log passwords, tokens, API keys, or PII