core-quality-py-unreachable-code

Pack: core-quality Default severity: MAJOR Languages: Python Lifecycle: experimental Confidence: 0.95

What it catches

Statements that follow return, raise, sys.exit() / exit() / quit(), continue, or break in the same block. The trailing code can never execute.

Why this matters for vibe-coded apps

Pure pivot debris — the developer (or AI) changed direction and left old code below the new exit. The risk isn't the dead line itself; it's that the AI fixing the next bug may try to "improve" code that never actually runs.

Example — flagged

def fetch_user(id):
    return user_repo.get(id)
    log_done(id)             # ← never runs

def shutdown():
    sys.exit(0)
    cleanup()                # ← process already terminating

Example — not flagged

def pick(x):
    if x > 0: return 'positive'      # last in if-block — fine
    return 'negative'

def loop():
    for i in range(3):
        if i % 2 == 0: continue       # last in if-block — fine
        print(i)

Implementation

Tree-sitter-python AST. Visits each block, classifies the last terminator, flags the FIRST statement that follows. Nested function / class definitions in the dead-code slot are skipped.

Source: `shared/packs/core-quality/core-quality-py-unreachable-code.ts` Fixtures: `corpus/rules/core-quality-py-unreachable-code/`