Dead Check — Dead Code Elimination

Hook coverage check (run first): Before running DEAD-1 detection, check whether the hook already flagged commented-out code blocks in this session for the file(s) in scope:

cat "$COVERAGE_FILE" 2>/dev/null   # COVERAGE_FILE = /tmp/codex-hook-coverage-<PROJECT_HASH>.jsonl

For each JSON line where "rule" is "DEAD-1", extract file, line, and end_line. When scanning, skip any file+line range that matches an existing coverage record. Log: "Skipping DEAD-1 at {file}:{line}-{end_line} — already reported by hook this session."

If no coverage file exists, proceed with the full DEAD-1 analysis.

For unused export and orphan detection: invoke scripts/lint_dead_code.py --path {scope} and parse its JSON output. Requires Python 3.12+ (python3.12 scripts/lint_dead_code.py --path {scope}).

Precedence in the overall system: SEC → TDD → ARCH/TYPE → NAME/SIZE/DEAD → quality BLOCK.

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What Counts as Dead Code

Category	Description
Commented-out code	Any block of syntactically valid code inside a // or /* */ comment
Unused export	An exported symbol with zero import references in the codebase
Orphaned file	A source file unreachable from any entry point via imports
Unlinked TODO	TODO: / FIXME: / HACK: without an issue tracker reference
Stub / placeholder	Function body that is only pass, throw new Error('not implemented'), todo!(), unimplemented!()

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Rules

DEAD-1 — No Commented-Out Code

Severity: BLOCK | Languages: * | Source: CCC

What it prohibits: Blocks of code that have been commented out rather than deleted. This includes single-line and multi-line commented code, regardless of how recently it was added.

Exemptions (not flagged):

• Single-line explanatory comments (non-code English prose)
• JSDoc / rustdoc / godoc comment blocks above declarations
• //nolint:, # noqa:, #[allow(...)] suppression comments
• Example code inside documentation comments (within /// or /** */)

Detection:

1. Grep for comment blocks where the content after removing comment markers (//, #, /*, *) is valid code syntax:
   • Contains assignment operators (=, :=)
   • Contains function call patterns (name()
   • Contains control flow (if , for , while , return )
   • Contains closing braces/parens (}, )) at line start
2. Multi-line comment blocks where ≥ 3 consecutive lines match the above
3. Flag each occurrence

agent_action:

1. Cite: DEAD-1 (BLOCK): Commented-out code block at {file}:{start_line}-{end_line}.
2. Show the commented block
3. State: "This code should be deleted. Git history preserves it if needed."
4. If --fix: delete the commented block (no confirmation required — git is the backup)
5. DO NOT preserve commented-out code when writing or refactoring

Bypass prohibition: "I might need it later", "it's a reference", "it documents what was tried" → Refuse. Cite DEAD-1. Write a commit message. Delete the code.

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DEAD-2 — No Unused Exports

Severity: WARN | Languages: typescript, javascript, python, rust | Source: CCC

What it prohibits: Exported/public symbols (functions, classes, constants, types) that are not imported or referenced anywhere in the codebase. These inflate public API surface area and imply tests must be written for them.

Go note: Go's compiler enforces unused imports natively. Unexported symbols in Go are not flagged by this rule — only exported (PascalCase) symbols.

Detection:

1. Run: python3.12 scripts/lint_dead_code.py --path {scope}
2. Parse JSON output — unused_exports array
3. Each entry: { "file": "...", "line": N, "symbol": "..." }

agent_action:

1. Cite: DEAD-2 (WARN): Unused export '{symbol}' at {file}:{line}.
2. Ask: "Is this export part of a public library API intended for external consumers?" If yes → add a suppression waiver. If no → delete.
3. If --fix and confirmed not part of public API: remove the export and its declaration if it has no internal usages either
4. Do not remove if any external consumer may exist (library context)

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DEAD-3 — No Orphaned Files

Severity: WARN | Languages: * | Source: CCC

What it prohibits: Source files that are not reachable from any entry point via the import graph. Orphaned files are often the remains of deleted features or refactored modules that were never cleaned up.

Entry points (heuristic — adapt to project):

• index.ts / main.ts / app.ts / server.ts
• main.py / __main__.py
• main.go
• main.rs
• Test files (*.test.*, test_*.py, *_test.go, #[cfg(test)] modules)

Detection:

1. Run: python3.12 scripts/lint_dead_code.py --path {scope}
2. Parse JSON output — orphaned_files array
3. Each entry: { "file": "...", "reason": "..." }

agent_action:

1. Cite: DEAD-3 (WARN): Orphaned file '{file}' — not reachable from any entry point.
2. Show possible reasons: deleted import, renamed module, leftover scaffold
3. ⚠️ Requires explicit confirmation before deletion — even in --fix mode
4. Present: "Proposed action: delete {file}. Proceed? (y/n)"
5. Only delete after explicit y confirmation

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DEAD-4 — TODOs Must Reference an Issue Tracker

Severity: WARN | Languages: * | Source: CCC

What it prohibits: TODO:, FIXME:, HACK:, XXX:, BUG: comments that do not reference an issue tracker ticket. Unlinked TODOs become permanent fixtures. Every deferred item must have an owner and a tracking number.

Compliant formats:

// TODO(#123): Implement retry logic after rate limiting
// TODO(GH-456): Remove after migration to v2 API
# FIXME(JIRA-789): Handle None case for legacy records
// HACK(#234): Temporary workaround for upstream bug — remove after v3.1

Non-compliant formats:

// TODO: fix this later
// FIXME: handle error
// HACK: temporary workaround

Detection:

1. Grep for TODO:, FIXME:, HACK:, XXX:, BUG: without a (#...) or (GH-...) or (JIRA-...) or ([A-Z]+-[0-9]+) pattern immediately after

agent_action:

1. Cite: DEAD-4 (WARN): Unlinked TODO at {file}:{line}: '{comment}'.
2. Propose conversion: TODO: {text} → TODO(#{issue_number}): {text}
3. If no issue exists yet: "Create an issue for '{text}' and add the reference."
4. If --fix: convert format to TODO(#?): {text} with ? as placeholder, noting that the issue number must be filled in

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DEAD-5 — No Placeholders or Stubs in Production Code

Severity: BLOCK | Languages: * | Source: CCC

What it prohibits: Functions in non-test code whose body consists only of:

• pass (Python)
• throw new Error('not implemented') / throw new Error('TODO') (TypeScript/JavaScript)
• todo!() / unimplemented!() (Rust)
• panic("not implemented") (Go)
• An empty body {}

These are scaffolding artifacts. They imply a contract without delivering it and will cause runtime failures when called.

Exemptions:

• Abstract method declarations in abstract classes (the stub IS the contract)
• Interface method signatures (no body)
• Test doubles / mocks in test files (*.test.*, test_*.py, etc.)

Detection:

1. Grep for throw new Error('not implemented'), todo!(), unimplemented!(), panic("not implemented") outside test files
2. Grep for single-statement function bodies containing only pass (Python), in non-test files

agent_action:

1. Cite: DEAD-5 (BLOCK): Stub/placeholder function '{name}' at {file}:{line}.
2. Options:
   • If this is a planned feature: create an issue, replace with a DEAD-4 compliant TODO comment above the function, and implement a minimal real body (even if it returns a zero value)
   • If this is scaffolding that was never implemented: delete the function and all call sites
3. DO NOT produce code that calls or wraps a stub function

Bypass prohibition: "I'll implement it later" → Refuse. Cite DEAD-5. Either implement the minimum viable version or delete it and track via issue.

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Report schema: see skills/conductor/shared-contracts.md.