Turn loop: drives a provider stream, dispatches tool calls, enforces max-turn and sequencing semantics, handles partial streams, retries on stream failure, propagates aborts.

Non-goals #

No tool implementations (pa-core), no providers (pa-ai), no session persistence, no UI. The loop is tool-agnostic: it receives a ToolDispatcher boundary.

Public API #

run_loop (session inputs -> stream of loop events), ToolDispatcher trait. types::Model carries the routed request descriptor, including advertised input modalities, through model switches and per-run overrides. Missing modalities stay unspecified; the provider boundary preserves the existing text-only interpretation. The loop does not discover capabilities or resolve provider routes. Loop internals pub(crate).

Depends on #

No workspace dependencies.