§ Playground·Live furqan-lint

One honesty check, three languages.

The same D11 status-coverage rule that ships in furqan-lint v1.0.0 (al-Basirah) runs against your Python, Rust, or Go function in the textarea below. Real subprocess, real verdict, real diagnostic. No model in the loop.

The checker reads your function's declared return type, walks the call graph one hop deep, and asks: does any callee declare a may-fail union the caller silently narrowed? That shape is the same defect across str | None in Python, Result<T, E> in Rust, and (T, error) in Go.

Switch to Diff to run the additive-only check across two versions of the same module. Public names you remove fire an additive_only marad.

Ready Folio 01

Single-file honesty check.

Verdict logic

PASS → No violations. Either the function declares the union honestly, or no callee returns one.

MARAD → One or more structural violations. The diagnostic names the producer, the consumer, and the minimal fix.

PARSE ERROR → The source could not be parsed. Reported with line and column. No checker runs on a broken AST.

Source .py

0 bytes · 100 KiB cap

or, load a fixture

Install locally: pip install "furqan-lint[go,rust] @ git+https://github.com/BayyinahEnterprise/[email protected]"

Stateless checks. Your source is written to a tmp file under /tmp, fed to furqan-lint check (or furqan-lint diff), then deleted. No source is logged. The sandbox imposes a 5-second wall-clock cap and a 100 KiB input cap per file. Share links persist a snapshot for 30 days.