Show HN: Jeff – A read-only CLI for semantic code review using Jev

Alurith released Jeff, a read-only Go command-line tool that semantically checks code files against 20 rules via the Jev engine from TypeSafe, running locally or in CI. Jeff exposes rules GEN001 through GEN020 covering issues such as unclear responsibility, weak error handling, missing input validation, and difficult-to-test structures, and requires a TYPESAFE_API_KEY or a credential stored through "jeff auth login" in the operating system keyring. The CLI emits text or JSON output via --output-format and returns exit code 0 for all checks passed, 1 for a conclusive violation, and 2 for usage, configuration, input, provider, internal, or inconclusive results.

Catch code issues before they catch you. A read-only Go CLI that semantically checks your files against your rules using Jev https://docs.typesafe.ai/introduction , locally or in CI. Check files in the current directory or at the provided paths jeff check --output-format text|json --no-cache PATH... Store or remove the TypeSafe credential jeff auth login jeff auth logout Set TYPESAFE API KEY or store a credential with jeff auth login . Stored credentials use the operating system's keyring; jeff auth logout removes the saved credential. Use TYPESAFE BASE URL to point to a compatible endpoint during testing. | Code | Rule | Description | |---|---|---| | GEN001 | Unclear responsibility | Finds files that mix unrelated responsibilities. | | GEN002 | Misleading naming | Finds important names that do not match their behavior or purpose. | | GEN003 | Excessive responsibility | Finds components responsible for too many distinct concerns. | | GEN004 | Low cohesion | Finds unrelated concepts, data, or dependencies grouped together. | | GEN005 | Hidden side effects | Finds significant side effects that are not apparent from the API. | | GEN006 | Weak error handling | Finds errors that may be hidden, ignored, or handled unsafely. | | GEN007 | Poor error context | Finds errors that lack useful diagnostic context. | | GEN008 | Missing input validation | Finds external or untrusted input used without adequate validation. | | GEN009 | Implicit assumptions | Finds important assumptions that are neither enforced nor documented. | | GEN010 | Unnecessary complexity | Finds implementations that are more complex than necessary. | | GEN011 | Premature abstraction | Finds abstractions that add complexity without a clear benefit. | | GEN012 | Inappropriate coupling | Finds unnecessary coupling between distinct components or concerns. | | GEN013 | Abstraction leak | Finds abstractions that expose implementation details to callers. | | GEN014 | Duplicated domain knowledge | Finds the same business rule or domain knowledge represented in multiple places. | | GEN015 | Redundant comments | Finds comments that restate code without adding useful information. | | GEN016 | Missing rationale | Finds non-obvious behavior without an explanation of why it exists. | | GEN017 | Fragile control flow | Finds control flow that is unnecessarily difficult to reason about. | | GEN018 | Invalid state representable | Finds designs that make invalid or contradictory state easy to represent. | | GEN019 | Poor boundary separation | Finds core logic mixed with infrastructure or external-system concerns. | | GEN020 | Difficult to test | Finds structures that make important behavior unnecessarily difficult to test. | Jeff is designed for both interactive CLI use and automation: - text output highlights failed checks and prints a summary; - --output-format json emits structured results and errors for CI; - 0 means all applicable checks passed; - 1 means a conclusive check found a violation and no error occurred; - 2 means a usage, configuration, input, provider, internal, or inconclusive result. Jev reference documentation is available in docs/references/jev https://github.com/Alurith/jeff/blob/master/docs/references/jev .