Add a server-sent-events reader to loopd

Implemented-By: Laguna S 2.1 (OpenCode)

docs/implementer-log.md

@@ -18,6 +18,7 @@ reviewer adds findings under "Reviews" once per milestone.
 | M2a/02-inferproxy | 2026-09-17 | done | 3 | fail | none | Implemented Limits/TokenBucket/OpenGuard/serve/handle/forward in lib.rs (std only: the inference server's JSON is upstream's concern) and arg parsing + stale-socket handling in main.rs; TokenBucket counts thousandths of a token in u128 so partial refills stay additive and `saturating_duration_since` on an earlier `now` never underflows, capping at burst; serve refuses by rate-limit then open-connection limit; handle drops its OpenGuard before closing the client so a freshly-finished client is not refused on re-connect (rule 4). The scaffold `proto` dependency in `crates/inferproxy/Cargo.toml` was left untouched since the task's Modify/Copy lists cover only lib.rs, main.rs, the two test files and this log. First `make gate` failed on `clippy::map_clone` (`main.rs` used `.map(String::clone)`); switched to `.cloned()` and re-ran, then re-ran once more after restoring the proto scaffold — both pass. Hand test against straylight returned `{"status":"ok"}`; `forward.rs` passed 6/6 ten runs in a row. |
 | M2a/03-loopd-config | 2026-09-17 | done | 1 | pass | none | Wrote crates/loopd/src/config.rs: Config + Infer/Slots/Expect/Sampling/Limits with deny_unknown_fields on all six and struct-level `#[serde(deny_unknown_fields, default)]` on Sampling and Limits; manual Default impls for the two; hand-written Display/std::error::Error ConfigError named by file. Everywhere check: all six structs (Infer, Slots, Expect, Sampling, Limits, Config) carry deny_unknown_fields. One local fix: Display used `{path}` on a PathBuf and failed to build, switched to `path.display()`. 6 config tests pass; `make gate` prints `gate: ok`. |
 | M2a/04-loopd-http | 2026-09-18 | done | 2 | fail | none | Added `pub mod http;` to crates/loopd/src/lib.rs and wrote crates/loopd/src/http.rs (423 lines): Request/Head/HttpError, send (exact header order, no `Content-Length` for GET), read_head (buffers across timeouts; `Timeout`/`Closed`/`TooLarge`/`Malformed`), parse_status+parse_head (`HTTP/1.1`/`HTTP/1.0`, status 100-599, lowercased names, duplicates kept, trimmed values), body (chunked/length/close; chunk extensions + trailers skipped), and read_capped. Two fixes: the chunk `Data` phase jumped to `Crlf` on `take==want`, but `want` was capped by the caller's buffer so it switched mid-chunk and returned `malformed chunk` on the recorded fixture — changed to switch on `chunk_remaining==0`; `read_length` reads straight into the caller buffer instead of an 8192 temp slice that would panic for readers larger than 8192. First gate failed on three clippy lints (needless borrows of `format!` results and `map_or` -> `is_some_and`), fixed on the second run. All 15 tests pass and `make gate` prints `gate: ok`. |
+| M2a/05-loopd-sse | 2026-09-18 | done | 2 | fail | none | Added `pub mod sse;` to crates/loopd/src/lib.rs and wrote crates/loopd/src/sse.rs: SseItem (Data, Done), SseError (Io, Timeout, Truncated, LineTooLong, NotUtf8) with Display/std::error::Error, and Events<R> which reads a line in bounded 4096-byte chunks, skipping blank/comment/other-field lines and stripping `data:` plus one leading space, decoding UTF-8 only once a whole line has arrived. Two fixes: `drain(..pos)` left the newline in the buffer so blank lines never advanced — changed to `drain(..=pos)` and pop the endings; `process_line` returns `Ok(None)` for a skipped line, which collided with `next_item`'s "stream ended" `Ok(None)` — restructured so a skip continues the loop and only a clean EOF sets `ended`. Both LineTooLong checks (mid-arrival and whole-read) verified by checking the accumulated length before reading and the finished line length. All 7 tests pass; first gate run failed on an unused import, fixed. |
 
 ## Reviews