SQL pools time out; task locks are a renewed five-minute lease

A 3-node rehearsal (PostgreSQL + NATS + Garage) found two ways a crash
leaves work stuck:

Pool hangs. The PostgreSQL pool (deadpool) was built with no timeouts,
so a request waited for a free connection, and for one to be opened or
recycled, for as long as it took: forever when the server stopped
answering. MySQL's pool (mysql_async) has no wait timeout at all.

- PostgreSQL: wait 30 s (or the store's timeout if longer), create the
  store's timeout or 15 s (it bounds the whole handshake, where
  tokio-postgres's connect_timeout covers only the TCP connect), recycle
  10 s. The pool config is now always set, not only with
  poolMaxConnections.
- MySQL: every connection is taken through MysqlStore::conn(), which
  gives up after 30 s.
- Both: TCP keepalive after 60 s idle, so a server that vanished
  without closing the connection is noticed in minutes rather than the
  two-hour system default.

The DataStore schema has no pool timeout settings, so these are fixed
defaults; the store's own timeout bounds connecting on PostgreSQL.

Task locks. A task lock lasted an hour, so after a hard crash the dead
node's tasks waited up to an hour and five minutes. The lock is now a
five-minute lease: while this node runs a task, the task manager renews
its lock every third of the lifetime (InMemoryStore::renew_lock, a
compare-and-set on the store backends and SET XX EX on Redis, which
leaves a lock that already expired alone). A killed node's tasks run
elsewhere within about five minutes plus the claim recheck. A task this
node holds isn't handed to a worker again by the scan.

store::pool_timeout (new): a local listener that accepts connections
and never answers plays a hung server; a PostgreSQL store with a 2 s
timeout returns an error in about 4 s, and a MySQL store in 30 s.
Without the timeouts both wait for good. store::task_locks gains a
task held for 1.5 lock lifetimes: its lease is still held, and released
when the task ends.

tests/src/store/pool_timeout.rs

@@ -0,0 +1,96 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! A database that accepts connections and then says nothing (a hung or
+//! half-dead server, a black-holed failover) gives a worker an error within
+//! the pool's timeouts. Upstream's pools had none, so the worker waited for
+//! good. No database is needed: a local listener that never answers plays
+//! the server.
+
+use registry::schema::structs::DataStore;
+use std::time::{Duration, Instant};
+use store::{Store, ValueKey, write::ValueClass};
+use tokio::net::TcpListener;
+
+/// Accepts connections on a local port and never sends a byte.
+async fn silent_server() -> u16 {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let port = listener.local_addr().unwrap().port();
+    tokio::spawn(async move {
+        let mut held = Vec::new();
+        while let Ok((socket, _)) = listener.accept().await {
+            held.push(socket);
+        }
+    });
+    port
+}
+
+/// Builds the store and reads a key; both must end, with an error for the
+/// read, well within `limit`.
+async fn assert_times_out(data_store: DataStore, limit: Duration) {
+    let started = Instant::now();
+    let result = tokio::time::timeout(limit, async {
+        match Store::build(data_store).await {
+            Ok(store) => store
+                .get_value::<u64>(ValueKey::from(ValueClass::Property(0)))
+                .await
+                .map(|_| ())
+                .map_err(|err| err.to_string()),
+            Err(err) => Err(err.to_string()),
+        }
+    })
+    .await;
+    let elapsed = started.elapsed();
+    match result {
+        Ok(Err(err)) => println!("Got {err} after {elapsed:?}"),
+        Ok(Ok(())) => panic!("a silent server answered?"),
+        Err(_) => panic!("still waiting for a connection after {elapsed:?}"),
+    }
+}
+
+#[cfg(feature = "postgres")]
+#[tokio::test(flavor = "multi_thread")]
+pub async fn postgres_pool_timeout() {
+    use registry::schema::structs::PostgreSqlStore;
+
+    let port = silent_server().await;
+    println!("Running PostgreSQL pool timeout test...");
+    // The store's own timeout bounds opening a connection, handshake
+    // included (tokio-postgres's connect_timeout covers only the TCP connect)
+    assert_times_out(
+        DataStore::PostgreSql(PostgreSqlStore {
+            host: "127.0.0.1".into(),
+            port: port as u64,
+            database: "none".into(),
+            timeout: Some(Duration::from_secs(2).into()),
+            use_tls: false,
+            ..Default::default()
+        }),
+        Duration::from_secs(20),
+    )
+    .await;
+}
+
+#[cfg(feature = "mysql")]
+#[tokio::test(flavor = "multi_thread")]
+pub async fn mysql_pool_timeout() {
+    use registry::schema::structs::MySqlStore;
+
+    let port = silent_server().await;
+    println!("Running MySQL pool timeout test...");
+    // mysql_async has no pool timeout; the store waits 30 s for a connection
+    assert_times_out(
+        DataStore::MySql(MySqlStore {
+            host: "127.0.0.1".into(),
+            port: port as u64,
+            database: "none".into(),
+            use_tls: false,
+            ..Default::default()
+        }),
+        Duration::from_secs(60),
+    )
+    .await;
+}