gatewayd: state, what was handled, our threads and turns in flight

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

docs/implementer-log.md

@@ -6,6 +6,7 @@ reviewer adds findings under "Reviews" once per milestone.
 
 | Task | Date | Status | Gate runs | First gate | Deviations | Notes | Model |
 |---|---|---|---|---|---|---|---|
+| M4a/12-gatewayd-state | 2026-09-23 | done | 1 | pass | none | Copied `tests/state.rs` and the `src/state.rs` skeleton, added `pub mod state;` to `lib.rs`. Filled `problem` (every `channels` key, `recent` and `threads` entry must be `valid_id` → "not a Mattermost id: <id with {:?}>"; each `in_flight` entry, session `mm-`+valid id with channel and root valid → "a turn in flight is not valid: <session with {:?}>"); `load` (NotFound → empty StateFile, any other read error, serde parse error or `problem()` → Read(path, why)); `save`/`persist` (the six atomic steps of brokerd's persist, io error mapped to Write, old file left on failure); `handled` (records unseen ids keeping the newest RECENT_KEPT, moves the channel mark to the max), `mark` (sets only a channel without a mark), `join_thread` (keeps the newest THREADS_KEPT), `start_turn`/`end_turn`/`take_in_flight` (removing by session, save only when in_flight was non-empty). Every mutating method saves before returning. All 4 tests pass in ~0.04 s; `make gate` prints `gate: ok` first run. | ? |
 | M4a/11-gatewayd-sessions | 2026-09-23 | done | 2 | fail | Removed the `resume` field from the copied `Pending` struct (written by the skeleton but never read) | Filled `named` (byte scan for `@`, the longest run of ASCII alnum/`.` `-` `_` after it, trailing `.` trimmed, lower-cased, empty runs skipped, then continue past the name) and the `Router` (`route` is a straight line of early returns in spec order: own -> Ignore(Own); kind not empty -> System; user not in allow.users -> NotAllowed; then the channel where "D" is always ours and "O"/"P"/"G" needs an allowed channel id plus `for_us`; the thread root is `root_id` or the post id; `!!...` keeps one `!` and queues, a lone `!` or `!approve`/`!deny` is a command where approve/deny answers M4B_COMMAND and anything else UNKNOWN_COMMAND, a command never reaches loopd; then Queue with session `mm-<root>`, `resume = root_id not empty`, `joins_thread = channel_type != "D"`). `for_us` is true when it names this bot (case-insensitive), otherwise a reply in a known thread that names only channel/here/all. `Queues`: `push` starts a turn when idle (Start with that message alone), waits while running and returns Full(thread) at the limit; `finish` joins the waiting texts with "\n\n" as a resume:true Batch, clears the queue and stays running, removing the session when nothing waits. `Pending.resume` was dead code (the next turn is always a continuation so `finish` hardcodes resume:true) so I removed it rather than allow a lint. First gate failed on clippy `manual_strip`; switched `starts_with("!!")`/`starts_with('!')` plus `&message[2..]`/`&message[1..]` slicing to `strip_prefix`. All 8 sessions tests pass; `make gate` prints `gate: ok` on the second run. | ? |
 | M4a/10-gatewayd-mm | 2026-09-23 | done | 1 | pass | none | Copied `tests/mm_json.rs`, `tests/mm_rest.rs` and `tests/support/http_server.rs`, added the `src/mm/mod.rs` and `src/mm/rest.rs` skeletons to `crates/gatewayd/src/mm/` and `pub mod mm;` to `lib.rs` (before `secrets`, alphabetical). Filled `mod.rs`: `Post::check` requires `id`/`user_id`/`channel_id` `valid_id` and `root_id` empty-or-`valid_id`, else `Json` quoting the offending id with `{:?}`; `json` is `serde_json::from_slice` mapped to `Json(e.to_string())`; `parse_event` matches `hello`/`posted`/other — `posted` takes `data.post` as a JSON *string* (an object or missing is `Json`), parses it, `check`s it, and reads `data.channel_type` (else ""), any other name (or an empty-name reply) is `Other(name)`; `typing` is `serde_json::json!` compacted; `since_list` walks `order` only (skipping ids not in `posts`, keeping `create_at > since && delete_at == 0` after `check`, deduping, then sorting by `(create_at, id)`), `full` when `order.len() >= SINCE_LIMIT`. Filled `rest.rs`: `Client::new` stores the three fields; `once` connects within `timeout`, sets the read timeout, sends `Authorization: Bearer <token>` (the only `expose`), `Accept`/`Content-Type` headers and `host_header`, mapping every error to `Net("<method> <path>: <e>")`; `call` loops `once` — 2xx returns the body, 401/403 `Auth`, 429 waits `rate_limit_wait` up to `RETRIES` then `RateLimited`, 5xx retried up to `RETRIES` times sleeping `RETRY_5XX`, else `Status` with the first `BODY_KEPT` lossy-UTF-8 chars via a `status_error` helper; `me`/`create_post`/`posts_since`/`direct_channel` build the four calls, `posts_since` and `me`/`direct_channel` reject non-`valid_id` ids as `Json` before sending. All 7 `mm_json` and 10 `mm_rest` tests pass (the latter ~3 s on two deliberate rate-limit waits); `make gate` prints `gate: ok` first run. | ? |
 | M4a/09-gatewayd-ws-conn | 2026-09-23 | done | 1 | pass | none | Filled the eight functions in the copied `crates/gatewayd/src/ws/conn.rs` skeleton (the written `poll` was the glue). `open`: `connector.connect(dead_after)` mapped to `Handshake(e.to_string())`, then `handshake` with `host_header(connector.server())`, a Ws with a new `Decoder` and `last_heard`/`last_ping` both `now`. `send`: `read_exact` 4 mask bytes from `random`, then `encode(opcode, payload, mask)` written and flushed. `send_text`: `send(TEXT, text.as_bytes())`. `take_messages`: loop `next_message`, `Text` returns, `Ping` answered with `send(PONG, &payload)`, `Pong` ignored, `Close` replies the code as 2 big-endian bytes (empty when none) via a best-effort `send(CLOSE, ...)` (the peer may be gone) and returns `Closed`. `keep_alive`: `now.duration_since(last_heard) >= dead_after` is `Dead`, else `now.duration_since(last_ping) >= ping_every` pings and stamps `last_ping`. `read_timeout`: the least of next-ping, next-dead and until-left (each `saturating_duration_since`), then `.max(1ms)`. `read_some`: `set_read_timeout`, a 16 KiB buffer, `Ok(0)` -> `Closed`, `Ok(n)` feeds `buf.get(..n).unwrap_or_default()` and stamps `last_heard`, `WouldBlock`/`TimedOut`/`Interrupted` -> `Ok(())`, any other `Err` -> `Io`. `close`: best-effort `send(CLOSE, &1000u16.to_be_bytes())`. `host_header`: host alone when the port is the scheme default (443 for tls, 80 otherwise) else `host:port`. All 10 tests in `tests/ws_conn.rs` pass five runs under a second; `make gate` prints `gate: ok` first run. | ? |