jeff

jeff check [--output-format text|json] [--no-cache] [PATH...]jeff auth loginjeff auth logout

jeff is a read-only Go CLI that reviews source files against a built-in catalog of semantic design rules. It does not parse or lint syntax. Each applicable rule is a Jev *noul* question from TypeSafe: the file contents are sent as *state* to the TypeSafe API, and the model returns a probability in [0, 1] that the rule's statement holds. Scores below 0.20 pass, scores at or above 0.80 are violations, and values in between are inconclusive.The embedded catalog is the GEN family (GEN001–GEN020): unclear or excessive responsibility, misleading names, low cohesion, hidden side effects, weak error handling, missing validation, unnecessary complexity, premature abstraction, coupling, leaked abstractions, duplicated domain knowledge, redundant comments, missing rationale, fragile control flow, representable invalid state, mixed infrastructure, and code that is hard to test. Rules apply per file. Markdown, plain text, hidden files, and vendor/ trees are excluded even when discovery walks them.With no paths, jeff check walks the current working directory. Directory walks honor nested .gitignore files and skip .git. An explicitly named file is always checked, even if gitignore would have skipped it. Symlink inputs are rejected. Files must be valid UTF-8 without NUL bytes.Text output prints only non-passing checks plus a summary of violations, inconclusive results, and errors. JSON is a single object with schema_version, checks, errors, and warnings. Successful answers are cached under .jeff-cache/v1/ in the invocation root so unchanged files are not re-sent.

check [PATH...]

Review files at the given paths, or the current directory when omitted.

Text (default) for interactive use, or JSON for CI parsers.

Do not read or write the answer cache.

Prompt for a TypeSafe API key (hidden on a TTY) and store it in the system keyring as service jeff, account typesafe-api-key. Accepts a single line on stdin when not a TTY.

Delete the stored keyring credential. Does not unset TYPESAFE_API_KEY.

Print usage. jeff check -h and jeff auth -h print the matching subcommand usage.

TYPESAFE_API_KEY

API key used when set. Overrides the keyring. Must be non-empty, at most 2048 bytes, and contain no NUL or newline.

TypeSafe API origin. Default https://api.typesafe.ai. Requests go to /v1/systemone. Useful for a compatible test endpoint.

Per-answer JSON cache under the invocation root, keyed by SHA-256 of the model, file contents, and question. Mode 0700 on the directory, 0600 on entries. just clean in the upstream repo removes .jeff-cache and bin.

Discovery for directory inputs loads gitignore patterns as it walks. Explicit file arguments skip this filter.

0

Every applicable check passed.

At least one conclusive violation, and no error or inconclusive result.

Usage error, missing or invalid credentials, unreadable input, provider failure, internal error, or an inconclusive noul.

jeff is read-only on disk, but it sends source file contents to TypeSafe over the network whenever the cache misses. Treat that as sharing code with a third party. It is not a substitute for a conventional linter: results are probabilistic judgments, not AST matches, so scores between 0.20 and 0.80 fail CI with exit 2. The rule catalog is compiled in; there is no flag to add, drop, or retune rules. The Go module path is jeff rather than a repository URL, so install from a clone with go build -o bin/jeff ./cmd/jeff (Go 1.25 or newer). Provider calls retry up to three times with a 10-second per-attempt timeout and a 30-second overall cap.

jeff was published by Alurith in September 2026 as a Show HN CLI that runs a fixed semantic-review catalog through TypeSafe's Jev model.

semgrep(1), ast-grep(1), golangci-lint(1), staticcheck(1), ruff(1)

Source code · Documentation