swarm-wire: take agent_schedules's wire types

swarm-wire/src/agent_inference.rs

@@ -7,11 +7,11 @@
 //! no swarm.
 //!
 //! **An agent reads with one `DIRECT.GET` on its own key, not a watch**, for
-//! the reason `swarm_queue_client::agent_schedules` gives: the direct get names the key
-//! in its subject ([`direct_get_subject`]), which is
-//! what lets the queue grant scope the read to one agent.
+//! the reason [`crate::agent_schedules`] gives: the direct get names the key
+//! in its subject ([`direct_get_subject`]), which is what lets the queue grant
+//! scope the read to one agent.
 //!
-//! Keyed by the agent alone, like `swarm_queue_client::agent_schedules`: an agent can
+//! Keyed by the agent alone, like [`crate::agent_schedules`]: an agent can
 //! move between hives.
 
 /// The KV bucket inference settings are published into, keyed by agent name.

swarm-wire/src/agent_schedules.rs

@@ -0,0 +1,147 @@
+//! The per-agent schedule KV bucket: one key per agent, holding the scheduled
+//! prompts that fire in that agent.
+//!
+//! **swarm-controller is the only writer**, and creates the bucket on its
+//! first write. It keeps each prompt once, with its name and every agent it
+//! goes to, and writes each agent's key as the prompts naming that agent,
+//! without the name or the other agents. Each agent's harness reads its own
+//! key and fires the schedules itself; the fire times are a pure function of
+//! each schedule ([`Schedule::latest_slot`]), so rewriting the list never moves
+//! them.
+//!
+//! **An agent reads with one `DIRECT.GET` on its own key, not a watch.** A KV
+//! watch is an unnamed consumer, whose create subject carries no filter, so
+//! granting it would grant every agent's key. The direct get carries the key
+//! in its subject ([`direct_get_subject`]), which is what lets the queue grant
+//! scope the read to one agent. It is also the agent's whole `JetStream` grant:
+//! `swarm_queue_client::agent_schedules::read_own` builds the stream handle
+//! without a `STREAM.INFO`.
+//!
+//! Keyed by the agent alone, like [`crate::agent_icon`], and for the same
+//! reason: an agent can move between hives.
+
+/// The KV bucket schedules are published into, keyed by agent name.
+pub const BUCKET: &str = "agent-schedules";
+
+/// The stream backing [`BUCKET`]. `create_key_value` prefixes `KV_`.
+pub const STREAM: &str = "KV_agent-schedules";
+
+/// The subject `agent`'s entry is stored under.
+#[must_use]
+pub fn key_subject(agent: &str) -> String {
+    format!("$KV.{BUCKET}.{agent}")
+}
+
+/// The request subject that reads `agent`'s current entry, and so the one
+/// subject the queue grants that agent in this bucket.
+#[must_use]
+pub fn direct_get_subject(agent: &str) -> String {
+    format!("$JS.API.DIRECT.GET.{STREAM}.{}", key_subject(agent))
+}
+
+/// The prompts that fire in one agent: the value under `BUCKET`/`<agent>`.
+#[derive(Debug, Clone, Default, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+pub struct AgentSchedules {
+    #[serde(default)]
+    pub schedules: Vec<Schedule>,
+}
+
+/// One scheduled prompt.
+///
+/// Its fire times are `anchor_unix + k * interval_seconds` for `k >= 0`, or
+/// `anchor_unix` alone when there is no interval.
+#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+pub struct Schedule {
+    /// Minted by the controller, the same in every agent the prompt names,
+    /// and never reused, so an agent's record of what it last fired for an
+    /// id cannot apply to a different schedule.
+    pub id: String,
+    /// The prompt, delivered verbatim as the todo's summary.
+    pub body: String,
+    /// The first fire time, unix seconds.
+    pub anchor_unix: i64,
+    /// Seconds between fires; `None` is a one-shot.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub interval_seconds: Option<u64>,
+    /// A paused schedule does not fire, and the slots that pass while it is
+    /// paused are not fired when it resumes.
+    #[serde(default)]
+    pub paused: bool,
+}
+
+impl Schedule {
+    /// The latest fire time at or before `now`, or `None` while the first is
+    /// still ahead.
+    #[must_use]
+    pub fn latest_slot(&self, now: i64) -> Option<i64> {
+        if now < self.anchor_unix {
+            return None;
+        }
+        let Some(interval) = self
+            .interval_seconds
+            .filter(|i| *i > 0)
+            .and_then(|i| i64::try_from(i).ok())
+        else {
+            return Some(self.anchor_unix);
+        };
+        let elapsed = now - self.anchor_unix;
+        Some(self.anchor_unix + elapsed - elapsed % interval)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn every(anchor_unix: i64, interval: Option<u64>) -> Schedule {
+        Schedule {
+            id: "abc".to_owned(),
+            body: "hi".to_owned(),
+            anchor_unix,
+            interval_seconds: interval,
+            paused: false,
+        }
+    }
+
+    /// The names the grant in `swarm-nats.nix` spells with `{agent}`.
+    #[test]
+    fn names_match_the_queue_grant() {
+        assert_eq!(STREAM, format!("KV_{BUCKET}"));
+        assert_eq!(key_subject("iris"), "$KV.agent-schedules.iris");
+        assert_eq!(
+            direct_get_subject("iris"),
+            "$JS.API.DIRECT.GET.KV_agent-schedules.$KV.agent-schedules.iris"
+        );
+    }
+
+    #[test]
+    fn slots_sit_on_the_anchor_grid() {
+        let s = every(1000, Some(60));
+        assert_eq!(s.latest_slot(999), None);
+        assert_eq!(s.latest_slot(1000), Some(1000));
+        assert_eq!(s.latest_slot(1059), Some(1000));
+        assert_eq!(s.latest_slot(1060), Some(1060));
+        assert_eq!(s.latest_slot(1000 + 60 * 7 + 5), Some(1000 + 60 * 7));
+    }
+
+    #[test]
+    fn a_one_shot_has_one_slot() {
+        let s = every(1000, None);
+        assert_eq!(s.latest_slot(999), None);
+        assert_eq!(s.latest_slot(1000), Some(1000));
+        assert_eq!(s.latest_slot(1_000_000), Some(1000));
+    }
+
+    /// Fields a newer controller adds must not cost an older agent its list,
+    /// and a list written without the optional fields decodes to a recurring
+    /// or one-shot schedule that is not paused.
+    #[test]
+    fn decoding_tolerates_missing_and_unknown_fields() {
+        let doc = r#"{"schedules":[{"id":"a","body":"b","anchor_unix":5,"note":"x"}],"rev":2}"#;
+        let decoded: AgentSchedules = serde_json::from_str(doc).expect("decodes");
+        let mut want = every(5, None);
+        "a".clone_into(&mut want.id);
+        "b".clone_into(&mut want.body);
+        assert_eq!(decoded.schedules, vec![want]);
+    }
+}

swarm-wire/src/lib.rs

@@ -8,6 +8,7 @@
 pub mod agent_icon;
 pub mod agent_inference;
 pub mod agent_limits;
+pub mod agent_schedules;
 pub mod agent_login;
 pub mod agent_status;
 pub mod builder;