Hold 0007's four states where two clock readings and a counter decide them

.github/coverage/pinned-surface

@@ -80,6 +80,7 @@ module  src/server/certificate.rs   The one exception 0029 admits to certificate
 module  src/server/federation.rs    Which second host a request may reach, and the deliberate act that admits one.
 module  src/server/recovery.rs      0045's schedule for a server that is gone: when the next probe is due, where the doubling stops, and the hour after which the core stops asking. A defect here is a radio kept busy overnight on a device in somebody's bag, or a server that came back and was noticed hours later.
 module  src/server/retry.rs        0038's one policy for every request the core makes: which kinds are retried inside a call, how many attempts one call may spend, the interval each wait is drawn over, and the deadline that ends it. A defect here retries something that changed the server, or keeps a caller waiting past the point 0007 says an answer is not coming.
+module  src/server/states.rs       0007's four states: when a request outstanding is late, when it is abandoned, which transport outcomes are evidence the server is absent, and how many abandonments make it unreachable. A defect here tells a person their server is gone because one endpoint was slow, or holds a screen on a spinner past the budget the number was divided out of.
 module  src/server/transport.rs     The bounds every request is carried inside: which deadline an attempt runs against, how many may be outstanding against one server, how long an idle connection may be reused, and how far a cancelled body is read. A defect here is a request that outlives the deadline a caller was promised, or a connection handed back to an origin it was never opened to.
 module  src/server/write_queue.rs  0047's order, coalescing and bound for every write the core makes to a server. A defect here delivers somebody's actions out of the order they took them, keeps a queue that grows with activity rather than with breadth, or drops what a person just did instead of what they did three weeks ago.
 module  src/cache/mod.rs            The store interface, the one failure it may report, and the key type 0041 derives.

src/server/mod.rs

@@ -37,6 +37,14 @@
 //! reason [`transport`] holds no socket, and it is where both spreads in this
 //! module take their draw.
 //!
+//! [`states`] holds 0007's four states: how long a request may be outstanding
+//! before it is late, when it is abandoned, that each of those is said once and
+//! never unsaid, which transport outcomes are evidence the server is absent, and
+//! how many abandonments with no success between them make the server
+//! unreachable rather than the request unlucky. It makes no request, for the
+//! same reason [`transport`] holds no socket, and where the last of its states
+//! hands over to is [`recovery`].
+//!
 //! [`federation`] holds what 0072 decides: a second host becomes reachable only
 //! through an act a person performed, against one server, naming what it shares,
 //! and revocable without the network. Which hosts may be contacted at all is
@@ -47,6 +55,7 @@ pub mod certificate;
 pub mod federation;
 pub mod recovery;
 pub mod retry;
+pub mod states;
 pub mod transport;
 pub mod write_queue;