Structured Tasks Runtime v1

Audience: maintainers, host integrators, and compiler contributors.

Status: implemented Rust host runtime with invocation-owned HTTPS work; HOSTED GREEN under the v0.4.0 release baseline. Language syntax and backend lowering remain open.

semaprax::structured_tasks::task_scope executes real user closures inside a lexical scoped-thread lifetime. A scope admits at most 64 tasks, rejects empty, NUL-bearing, and duplicate stable identities, starts workers in canonical identity order, shares one cooperative cancellation token, and joins every worker before returning. Closures may borrow non-'static values because the scoped-thread type system prevents escape.

The first failed result in canonical report order is sticky. Semantic, nonzero-physical, cancellation, and panic outcomes trigger cancellation; siblings may observe it through is_cancelled or cancellation_point, but all started work drains. Reports are canonical regardless of completion order.

TaskScope::spawn_https_get moves one explicit NetworkProvider into a lexical task and returns its bytes through an HttpsTaskOutput slot. Callers inspect that slot only after task_scope returns. The provider settles exactly once before publication on success and HTTP failure, and also settles on pre-start cancellation, provider panic, invalid deadline, or rejected task registration. HTTP failures remain typed in the output slot and project their exact nonzero semaprax.http.v1 code into the task report.

HTTPS deadlines are caller-selected in 1ns..=30s. Cancellation is checked before entering transport. Once blocking TLS/HTTP work starts it drains, in accord with the scoped-task model; if it completes after the deadline, its response is discarded and the task reports DeadlineExceeded. This is a bounded blocking host integration, not preemptive cancellation or an async executor.

This is the real-execution foundation corresponding to Deterministic Scoped Task Model v1. It does not yet expose SEMAPRAX syntax, HIR/Graph task nodes, Sendable/Shareable analysis, dependency scheduling, schedule replay, async I/O, or native/Wasm task lowering.

Focused evidence:

cargo test --locked --lib structured_tasks::tests::

The implemented scoped-runtime and HTTPS-settlement release corpus is hosted green. Historical local observations remain witnesses of their original runs; they do not turn the Rust host integration into language-level tasks or a new backend execution model.