Imported from paudley/gmeow-proxy (.claude/skills/lint-remediation/SKILL.md). Install upstream with npx skills add paudley/gmeow-proxy --skill lint-remediation. Copyright stays with the author.

ETHOS-Grounded Lint Remediation

Use this skill to convert linter output into concrete refactoring work grounded in ETHOS, especially when an agent is tempted to silence the finding or weaken the rules.

ETHOS Grounding

• static-analysis-is-the-first-line-of-defense: Make ruff and mypy blocking quality gates rather than advisory tools.
• linting-as-code-quality-enforcement: Resolve lint findings with structural fixes; suppress only with documented necessity.
• universal-responsibility: Own every error or warning you touch and verify claims with evidence.
• solid-is-law: Enforce SOLID and simplicity; remove speculative abstractions.

Short Hint

Linters are enforced code reviewers. Fix findings structurally, keep managed config intact, and suppress only when technically necessary and fully documented.

Use When

• ruff
• mypy
• pyright
• pylint
• bandit
• sqlfluff
• lint failure
• type error
• noqa
• suppression

Remediation Workflow

1. Classify each finding by the code-quality concern it represents, not by the tool name alone.
2. Prefer structural fixes: split responsibilities, tighten types, remove dead paths, parameterize unsafe operations, or clarify contracts.
3. Do not edit generated lint config, broaden ignores, or add suppressions to get green faster.
4. If a suppression is genuinely necessary, document why the alternatives are worse and keep the scope as small as possible.
5. Verify with the managed coding-ethos tool path and report the exact checks that now pass or still fail.

Principle Details

Static Analysis is the First Line of Defense

We rely on linters (ruff) and type checkers (mypy) to catch errors before the code ever runs.

Directive: Make ruff and mypy blocking quality gates rather than advisory tools.

Quick ref:

• Use make release-audit for the full local gate.
• Use make -C coding-ethos parent-lint for coding-ethos policy lint.
• Keep parent lint scoped to production code; tests are verified by pytest.

Overview

We rely on linters (ruff) and type checkers (mypy) to catch errors before the code ever runs.

• We do not suppress linter errors unless absolutely necessary.
• Type hints are mandatory, not optional.
• If the CI pipeline fails static analysis, the code is effectively broken.

Machine-Enforced Gates

Static analysis belongs in enforced local hooks and CI, not in optional tribal knowledge.

• Repos should run their canonical lint and type suites automatically before code lands.
• If a repo exposes pre-commit, pre-push, or CI static analysis gates, treat them as part of the engineering contract.
• Passing the current local gate matters more than saying a previous run was green.

Repo Addendum

Gmeow uses project-local Makefile targets as the stable command surface for agents and CI. Prefer those targets so uv, pytest, build, and release hygiene checks remain consistent.

Linting as Code Quality Enforcement

Linters are not suggestions; they are automated code reviewers enforcing our standards.

Directive: Resolve lint findings with structural fixes; suppress only with documented necessity.

Quick ref:

• Resolve lint findings with structural fixes; suppress only with documented necessity.
• Linters are not suggestions; they are automated code reviewers enforcing our standards.
• Do not weaken hooks or broaden suppressions just to get green faster.

Overview

Linters are not suggestions; they are automated code reviewers enforcing our standards. We work with them, not around them.

SOLID-First Resolution

When a linter flags an issue, the correct response is to apply SOLID principles to resolve it properly:

• Long functions? Apply SRP—split into focused, single-responsibility units.
• Too many parameters? Apply ISP—consider configuration objects or dependency injection.
• Complex conditionals? Apply OCP—use polymorphism or strategy patterns.
• Tight coupling? Apply DIP—introduce abstractions and inject dependencies.

We do not silence linters because refactoring feels inconvenient.

Suppression Policy

Lint suppressions are a last resort, permitted only when:

1. Technical necessity: The suppression is genuinely required (e.g., a false positive from the linter).
2. Inferior alternatives: All workarounds would make the code demonstrably worse.
3. Full documentation: The suppression includes a clear explanation of why it exists.

Required Documentation for Any Suppression:

• Why the suppression is necessary
• Why alternatives are technically inferior
• Reference to any relevant issues or discussions

Example of Acceptable Suppression:

# noqa: E501 - SQL query string must remain on single line for readability
# and to match the query plan documentation. Breaking across lines would
# obscure the join structure. See: docs/query_patterns.md#complex-joins
query = "SELECT a.id, b.name, c.value FROM table_a a JOIN table_b b ON ..."

Active Maintenance

When working on code that contains suppression comments, you must evaluate whether they are still necessary:

• Can the underlying issue now be fixed properly?
• Has the codebase evolved to make a better solution possible?
• Is the suppression documented adequately?

If a suppression is no longer justified, remove it and fix the issue.

Enforcement Machinery Is Part of the Contract

Pre-commit, pre-push, and CI lint gates are part of normal development, not optional wrappers.

• Do not weaken hook configuration to get a green result faster.
• Do not introduce broad file-level ignores, pyproject ignore blocks, or comment suppressions as convenience escape hatches.
• Do not use environment-variable bypasses such as SKIP= to drop selected gates out of the commit flow.
• Fix the code, or document a principled and reviewable exception when the rule itself is wrong.

Anti-Patterns (Forbidden)

• ❌ Adding # type: ignore without explanation
• ❌ Blanket file-level suppressions (# noqa at the top of a file)
• ❌ Disabling rules in pyproject.toml because "there are too many warnings"
• ❌ Using suppressions to avoid refactoring
• ❌ Copying existing suppression patterns without understanding why they exist

The Audit Trail

Every suppression tells a story. Future maintainers must be able to understand:

1. What triggered the suppression
2. Why it couldn't be fixed properly
3. Under what conditions the suppression could be removed

Undocumented suppressions are technical debt masquerading as solutions.

Universal Responsibility

Every bug and every lint warning is everyone's responsibility.

Directive: Own every error or warning you touch and verify claims with evidence.

Quick ref:

• Own every error or warning you touch and verify claims with evidence.
• Every bug and every lint warning is everyone's responsibility.
• We do not accept excuses based on the origin of a problem.

Overview

Every bug and every lint warning is everyone's responsibility. There is no such thing as "pre-existing" or "not my code."

No Exemptions

We do not accept excuses based on the origin of a problem. If you can see it, you own it.

• All errors are in scope: Type errors, lint warnings, test failures—regardless of when they were introduced.
• All warnings need addressing: A warning is a latent bug waiting to manifest.
• No "pre-existing" carve-outs: The commit history is irrelevant to your responsibility.

Anti-Patterns (Forbidden Thinking)

The following rationalizations are explicitly banned:

• ❌ "This is a pre-existing error, not related to my work."
• ❌ "These warnings were present on main, so I can ignore them."
• ❌ "I didn't introduce this bug, so it's not my problem."
• ❌ "The CI was already failing before my changes."

The Correct Way

Correct thinking sounds like this:

• ✅ "There are 240 lint warnings in this branch. I need a systematic strategy to fix them before I commit."
• ✅ "This type error predates my changes, but I'll fix it now while I understand the context."
• ✅ "The test suite has 3 flaky tests. I'll stabilize them before adding my new tests."

Verification Is Your Responsibility

Claims require evidence. Assertions require verification.

• ❌ Claiming "I verified this works" without actually running tests

• ❌ Asserting a file exists without using Glob or ls to check

• ❌ Stating "this function does X" without reading its implementation

• ❌ Assuming code behavior without tracing the execution path

• ✅ "I ran the test suite and all tests pass"

• ✅ "I verified the file exists at src/app/storage.py"

• ✅ "Based on reading lines 45-60, this function returns..."

• ✅ "I have not verified this assumption—let me check"

The Rule: If you touch a file, you leave it cleaner than you found it. If you see a problem, you fix it or you file an issue—but you do not pretend it doesn't exist.

(See also: Section 20: Forward Motion Only for the forward-looking mindset that prevents blame culture.)

SOLID is Law

We do not view the SOLID principles as academic suggestions.

Directive: Enforce SOLID and simplicity; remove speculative abstractions.

Quick ref:

• Enforce SOLID and simplicity; remove speculative abstractions.
• We do not view the SOLID principles as academic suggestions.
• SOLID governs structure; these principles govern complexity:

Overview

We do not view the SOLID principles as academic suggestions. They are the strict rules of engagement for our codebase.

• Single Responsibility (SRP): Modules must have one reason to change. If a class handles storage I/O and metadata parsing, it is broken. Split it.
• Open/Closed (OCP): The system grows by adding new classes (extensions), not by editing existing ones. We use registries and dependency injection to introduce new behaviors.
• Liskov Substitution (LSP): A ServiceProvider must behave like a ServiceProvider. If your implementation raises unexpected exceptions or violates the protocol contract, it is a bug.
• Interface Segregation (ISP): Clients should not depend on methods they do not use. We prefer small, specific Protocols in interfaces/ over monolithic base classes.
• Dependency Inversion (DIP): We depend on abstractions (Protocols), not concretions. The Dependency Injection container (the DI container) is the heart of the application; manual instantiation of service chains in business logic is forbidden. (See Section 12: Protocol-First Design for how we implement this.)

Beyond SOLID: Simplicity Precepts

SOLID governs structure; these principles govern complexity:

• YAGNI (You Aren't Gonna Need It): Do not build for hypothetical future requirements. If the feature isn't needed today, don't add it. Abstractions "for future flexibility" are premature complexity. Build the simplest thing that works.

• KISS (Keep It Simple, Stupid): When choosing between approaches, prefer the simpler one. A 10-line function with duplication beats a 50-line abstraction. Clever code is a liability. Code should be boring.

• Principle of Least Astonishment (POLA): APIs, functions, and behaviors should do what their names suggest. If a function named get_user() modifies the database, it is broken regardless of whether it "works." No surprises.

• Law of Demeter (Don't Talk to Strangers): A method should only call methods on: (1) itself, (2) its parameters, (3) objects it creates, (4) its direct dependencies. Chains like user.address.city.name violate this—each dot is a coupling point that makes code brittle.

• Composition over Inheritance: Prefer composing objects from smaller components over deep inheritance hierarchies. In Python, use Protocols for interfaces and inject dependencies rather than inheriting behavior. Inheritance creates tight coupling; composition creates flexibility.

Anti-Patterns to Watch For:

• ❌ Adding a config system for values that could be constants
• ❌ Creating an abstract base class for a single implementation
• ❌ Adding optional parameters "in case someone needs them later"
• ❌ Building plugin architectures when a simple import would suffice
• ❌ Chaining through multiple objects to get data (violates Demeter)
• ❌ Creating deep inheritance hierarchies when composition would work
• ❌ Null Objects for "deployment flexibility" when the dependency is always required

The Rule: The best code is the code you didn't write. Every abstraction must earn its place by solving a problem that exists TODAY, not one that might exist tomorrow.

Output Discipline

When explaining a fix, name the ETHOS principle, the concrete code change, and the verification evidence. Do not recommend weakening lint config or adding suppressions unless the ETHOS policy explicitly allows it.