decoders

Reject reserved protocol channel names before they hit the fallback.

Genuine extension names pass through untouched; only names that infer_channel treats as built-in methods without an interleave decoder are rejected, so a typo'd or unsupported protocol channel surfaces an error instead of an empty stream.

Yields params.data from events of a single method.

Covers the channels whose projection is just "emit the payload": values, updates, checkpoints, tasks — the SDK analog of local's Values/Updates/Checkpoints/TasksTransformer, all of which push params["data"] unchanged. The REST-state seeding for values stays at the projection layer; it is a one-shot pre-stream fetch, not part of the event state machine.

Yields one chat-model stream per message-start event.

Subsequent events route to the matching stream via stream.dispatch(data). Mirrors the per-event body of _MessagesProjection._messages_iter (_async/stream.py:404-458). The subscription open/close and the _root_messages_inbox drain branch stay at the projection layer.

Yields one tool-call handle per tool-started event.

Mirrors the per-event body of _ToolCallsProjection._tool_calls_iter (_async/stream.py:1168-1217). The thread register/unregister and the terminal-error-on-close finally stay at the projection / wrapper layer.

Discovers child subgraph handles and fans out events to active ones.

Mirrors the per-event body of _SubgraphsProjection._subgraphs_iter (_async/stream.py:963-1041) plus _apply_tasks_result. Root-inbox forwarding and terminal-status-on-close stay at the projection / wrapper layer.

Yields params.data from one named custom channel.

Mirrors _ExtensionProjection._iter (_async/stream.py:1278-1299), with an added name filter so it can share one subscription in interleave.