The Checker

@arv/threads-check reports what TypeScript's types can't see, in CI, like a linter.

The checker runs in CI, like a linter. It reports what TypeScript's types can't see:

• A value used after it was sent.
• An alias of something sent.
• Sending what the caller still holds.
• A write to a shared value through a cast.
• A number that may not be an integer, stored into an i32 or a u8 (see Shared Memory).
• A blocking call in an async function (see Go-Style Concurrency).

Here's how you run it, and what an error looks like:

npx @arv/threads-check -p tsconfig.json --runtime @arv/threads

app.ts(23,16): error TS96007: 'order' cannot be sent: it may be referenced by the caller. Declare the parameter 'Sending<T>' to take ownership.

The checker needs no fork. @arv/threads-check runs on stock TypeScript 7.1's API.

The checker reads the source, so it reports the same errors whether a program is compiled or runs with its types only erased (see Performance).

The tutorial shows how the checker follows each value through a function, and the mistakes it catches.