Module client 

I4 (#1970): the typed TypeScript client for a context’s foreign callers, workers/<context>/bynk-client.ts (design/archive/retired-tracks.md, interop track D3).

A Bynk caller of another context gets a typed call: the compiler builds the path, stamps the contract hash, encodes the arguments and decodes the result. This module gives a Worker that is not Bynk the same, as a module it imports: one typed function per on call service a declared foreign caller may call, the boundary types as TypeScript types, and the contract hashes and wire version embedded as literals.

One codec, one caller

Nothing here is a second implementation of the boundary. The codecs are the ones a Bynk consumer generates for a callee’s types (serialisation::emit_helpers_for_owner_qualified under a non-empty qualifier, which inlines a transparent refinement and casts an opaque one), each call goes through the runtime’s own callService, and the encode and decode references at each call site come from the same serialisation::serialise_expr_via / serialisation::deserialise_ref_via the Bynk call site uses (emit.rs’s cross-context call lowering). The runtime half ships as @bynk/wire-client, bundled from the runtime’s own modules and versioned with the wire format (§11 Q7).

Signing as a foreign caller

I3’s hand-off gives the foreign Worker its secret under the name a Bynk caller holds its edge key by, BYNK_CALL_TO_<CALLEE>, and the callee’s verifier checks a declared foreign caller’s name against its own secret (__FOREIGN_CALLERS). So callService with the actor’s name as the caller signs exactly the request the callee admits. The client asks for the foreign Worker’s env (typed to require the secret) and its Service Binding.

When it is emitted

Only for a context that declares at least one Foreign actor some on call handler admits, and only with the services such an actor may call. A context with no foreign caller has no one the client could sign as: an undeclared caller holds no secret (§8 D2, §11 Q5).

Constants

CLIENT_FILE

The file, beside the Worker’s bynk-contracts.json. Hyphenated like the other compiler-written files there, so no Bynk unit can emit a module of the same name.

CLIENT_PACKAGE

The runtime package the client imports (§11 Q7).

Functions

foreign_contracts

The contract hash each declared foreign caller may call each service at: actor → service → hash. What a foreign caller’s generated client embeds, so what bynk deploy compares a pin against. Empty when the context admits no foreign caller.