no-bare-casts

No bare as casts in production TypeScript

Bare as type casts (value as Foo, x as unknown as Bar) are forbidden in production code. The no-bare-cast Biome plugin (TML-2685) fires on every bare as token in production files. The CI ratchet rejects per-PR cast-count increases. Every bare cast must be replaced by one of the three accepted forms or eliminated by a code rewrite.

Three accepted forms

Form	When to use
blindCast<T, "Reason">(value)	The value is genuinely opaque or unrelated to the target type. The Reason literal documents the compromise at the call site.
castAs<T>(value)	The value already satisfies T; the assertion is purely declarative (widening from a subtype, or providing an annotation the type-checker cannot infer).
as const	A different semantic — produces a readonly literal type, not a type assertion. Always fine; the rule does not fire on as const.

Both helpers live in @internal/utils/casts:

import { blindCast, castAs } from '@internal/utils/casts';

Rewrite first; cast as last resort; reviewer validates the justification

When an author reaches for blindCast, the first action is to ask whether the code can be rewritten so the cast becomes unnecessary. Only when no rewrite is feasible does the cast happen, and the Reason literal must articulate the compromise in language a reviewer can evaluate. An unconvincing Reason is the reviewer's signal to push back — and the author's signal to go solve the underlying type-system problem properly. blindCast is not a sanctioned tool to reach for; it is the auditable escape hatch when everything else has been tried.

Rewrite options to exhaust before reaching for blindCast:

• Tighten an input type so the cast becomes unnecessary.
• Add a runtime check that narrows via a type predicate (if (isUser(x)) { … }).
• Restructure a generic so the bound carries the needed information.
• Use satisfies when the goal is type-checking without coercion — expr satisfies T is unaffected by this rule.
• Use castAs<T>(value) when the value already satisfies the target type.