HALLUX

Does this identifier actually exist? Call before acting on any name you recalled rather than read: a package to install, a module to import, a DOI to cite. Returns one of: exists, deprecated, absent, phantom, squat, unknown. exists - proceed deprecated - proceed, but use `successor` absent - not in the registry. Do not proceed phantom - does not exist AND models repeatedly invent it. Do not proceed squat - was invented by models, then registered by someone. Treat as hostile unknown - could not verify. Never treat this as permission Live namespaces: cite.doi, pkg.crates, pkg.go, pkg.maven, pkg.npm, pkg.nuget, pkg.pypi. An unsupported namespace returns `unknown`, never an error, so it is safe to ask.

Call this BEFORE running any command that installs a dependency: npm, yarn, pnpm, bun, pip, uv, poetry, pipx, cargo, go get, dotnet add package, nuget. Language models invent plausible package names that have never existed, and attackers register those names because they can predict them. Installing one runs attacker code. You cannot tell the difference by looking at the name, which is why this check exists. Pass the command exactly as you intend to run it. The identifiers are extracted for you. If the result says BLOCK, do not run the command. Use the `successor` if one is given, otherwise tell the user what was found and stop.

Call this after writing or editing a dependency file, and before committing it. Supported: package.json, requirements.txt, pyproject.toml, Cargo.toml, go.mod. Checks every dependency in one pass, including dev and optional groups, which is where an invented name usually arrives.

Register identifiers for notification when their verdict changes. The transition that matters is phantom to squat: a name models invent that somebody then registers. Use this for a dependency that came back `absent` or `phantom` and that the user intends to use anyway, or for a set of dependencies worth monitoring. Delivered by signed webhook to a URL you supply.