PAGI-0.002001

Changes for version 0.002001 - 2026-06-30

Specification updates
- Application/middleware return value is now specified as inert: the server assigns the resolved value no meaning and acts only on the Future (completion/errors) and on events plus connection facts. Frameworks may use return values for their own composition but must convert them to events at the gateway boundary; a value must not escape to the server as the result.
- Middleware section: clarified that middleware propagate the inner Future (not a value) and observe/rewrite responses by wrapping $send/$receive; removed a stranded comment from the example.
- Added the sse.close send-event: an explicit, application-initiated end to an SSE stream (the SSE analog of http.response.body{more=>0}), ending it immediately and decoupled from the application returning. Optional reason field is server-side metadata only -- never transmitted to the client (SSE has no close frame, unlike websocket.close). After sse.close, further sse.send/sse.comment/sse.keepalive MUST raise; sse.close is idempotent. Returning after the final sse.send remains a valid way to end a stream.
- Added sse.http.response.start / sse.http.response.body send-events: before sse.start, an application MAY decline the stream and return a normal HTTP response (404, 401, a 204 to stop EventSource reconnection, a redirect, ...). Namespaced under sse. (mirroring the websocket.http.response denial events) so an sse scope only carries sse.* events. First-send-wins: after sse.start these are invalid; after sse.http.response.start the stream events are invalid (both MUST raise). Unlike the WebSocket denial extension this is a core capability (no event-stream fallback exists), so every conforming server MUST support it.
Documentation
- Cookbook: new SERVER-SENT EVENTS recipe "Ending a stream: return vs sse.close" -- the two termination paths (identical on the wire), the server-side-only reason, and observing close events by wrapping $send.
- Tutorial: new Part 2 section "2.8 Middleware: Wrapping an Application" teaching the pure $app -> $app pattern (scope cloning, wrapping $send/$receive, short-circuiting, error propagation, the inert return value, and stacking). UTF-8 and async-pitfalls sections renumbered to 2.9 and 2.10.