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Formless Host

Seven HPP/2 SDKs

Generated sources are committed for C++, C#, Go, Java, JavaScript, Python, and Rust. Each contains protobuf message types plus the same minimal SessionState contract.

contracts/v2/sdk/
├── cpp/
├── csharp/
├── go/
├── java/
├── javascript/
├── python/
└── rust/

Generation versions and every artifact hash live in contracts/v2/sdk/GENERATION.json. Regenerate only with the pinned repository script:

Terminal window
cd contracts
./scripts/generate-hpp2-sdks.sh
npm test

The generated layer is the frozen cross-language wire surface. Rust production plugins additionally use formless_host::hpp2_sdk for the UDS gRPC session, bounded queues, provider dispatch, broker calls, subscriptions, cancellation, and lifecycle commands.

Request pattern

Section titled “Request pattern”
  1. Allocate a unique correlation ID and next sequence.
  2. Register the request before sending its envelope.
  3. Accept zero or more non-terminal diagnostics/progress frames allowed by the contract.
  4. Complete exactly once on result, error, or cancellation.
  5. Record unknown or late terminals without mutating completed state.

Subscription pattern

Section titled “Subscription pattern”

Subscriptions are long-lived and are not bounded by an arbitrary request timeout. They remain active until cancellation, generation teardown, provider withdrawal, or a terminal stream condition. Apply bounded buffering and explicit backpressure rather than silently dropping lifecycle ownership.