swarmctl: agent set-state declares an agent's wanted state

Wraps PUT /api/hives/{hive}/agents/{agent}/state, the route the swarm UI's
state menu uses. States come from swarm_wire::wanted::AgentState; destroyed
needs --yes.

Closes #6159

swarmctl/src/agent.rs

@@ -112,6 +112,51 @@ pub(crate) fn mint_forge_token(target: &Target, name: &str) -> Result<()> {
     Ok(())
 }
 
+/// Parse a state as the wire enum spells it, so the accepted values are
+/// `swarm_wire::wanted::AgentState`'s and the error lists them.
+pub(crate) fn parse_state(value: &str) -> Result<swarm_wire::wanted::AgentState, String> {
+    serde_json::from_value(serde_json::Value::String(value.to_owned())).map_err(|e| e.to_string())
+}
+
+/// Refuse `destroyed` unless the operator confirmed it.
+fn check_confirmed(state: swarm_wire::wanted::AgentState, yes: bool) -> Result<()> {
+    if state == swarm_wire::wanted::AgentState::Destroyed && !yes {
+        bail!("`destroyed` can't be undone: pass --yes to declare it");
+    }
+    Ok(())
+}
+
+/// Run `swarmctl agent set-state`: `PUT /api/hives/{hive}/agents/{agent}/state`.
+pub(crate) fn set_state(
+    target: &Target,
+    agent: &str,
+    hive: &str,
+    state: swarm_wire::wanted::AgentState,
+    yes: bool,
+) -> Result<()> {
+    check_confirmed(state, yes)?;
+    let agent = parse_ident(agent, "agent name")?;
+    let hive = parse_ident(hive, "hive")?;
+    let wire: &'static str = state.into();
+
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .context("starting a tokio runtime for the controller request")?;
+    rt.block_on(send::<_, serde_json::Value>(
+        target,
+        hyper::Method::PUT,
+        &format!("/api/hives/{hive}/agents/{agent}/state"),
+        Some(&serde_json::json!({ "state": wire })),
+        "set-state",
+    ))?;
+
+    println!(
+        "declared agent {agent:?} {wire} on hive {hive:?}; the hive converges on its own clock"
+    );
+    Ok(())
+}
+
 /// One `POST /api/agents` round trip at the controller.
 async fn post_create(
     target: &Target,
@@ -280,7 +325,33 @@ fn connect_hint(socket: &Path) -> String {
 
 #[cfg(test)]
 mod tests {
-    use super::{describe_error, parse_ident};
+    use super::{check_confirmed, describe_error, parse_ident, parse_state};
+    use swarm_wire::wanted::AgentState;
+
+    /// The accepted values are the wire enum's: each spelling it writes
+    /// parses back, and an unknown one names the valid ones.
+    #[test]
+    fn states_parse_through_the_wire_enum() {
+        for state in [
+            AgentState::Up,
+            AgentState::Offline,
+            AgentState::Paused,
+            AgentState::Destroyed,
+        ] {
+            let wire: &'static str = state.into();
+            assert_eq!(parse_state(wire), Ok(state));
+        }
+        let err = parse_state("sleeping").expect_err("unknown state");
+        assert!(err.contains("paused"), "{err}");
+    }
+
+    #[test]
+    fn destroyed_needs_yes() {
+        assert!(check_confirmed(AgentState::Destroyed, false).is_err());
+        assert!(check_confirmed(AgentState::Destroyed, true).is_ok());
+        // Control: the other states don't ask.
+        assert!(check_confirmed(AgentState::Paused, false).is_ok());
+    }
 
     /// The whole point of parsing problem+json: the 400 for an unknown
     /// hive carries the roster of hives that would have worked, and that

swarmctl/src/main.rs

@@ -279,6 +279,19 @@ enum AgentVerb {
     /// Queues and returns, the same way `agent create` does — watch the
     /// swarm UI's job view for the outcome.
     MintForgeToken(AgentMintForgeTokenArgs),
+    /// Declare the state a hive converges an agent to: `up`, `offline`,
+    /// `paused` or `destroyed`.
+    ///
+    /// Writes the swarm's declaration for the agent, the one the swarm UI's
+    /// state menu writes, and returns once the controller has published it;
+    /// the hive converges on its own clock. The swarm must already know the
+    /// agent on `--hive`: this never creates one.
+    ///
+    /// `destroyed` can't be undone, so it needs `--yes`.
+    ///
+    /// No approval gate guards this: the caller is root on the controller's
+    /// host, or logged in through the swarm domain's SSO gate.
+    SetState(AgentSetStateArgs),
     /// Show the model, effort, subagent models and subagent cap the swarm sets
     /// for an agent, or change the model, effort and subagent models.
     ///
@@ -415,6 +428,23 @@ struct InferenceSetArgs {
     socket: ControllerSocketArg,
 }
 
+#[derive(Args)]
+struct AgentSetStateArgs {
+    /// Agent name.
+    agent: String,
+    /// The hive that runs the agent.
+    #[arg(long, value_name = "HIVE")]
+    hive: String,
+    /// The state to declare: `up`, `offline`, `paused` or `destroyed`.
+    #[arg(value_name = "STATE", value_parser = agent::parse_state)]
+    state: swarm_wire::wanted::AgentState,
+    /// Confirm `destroyed`, which can't be undone.
+    #[arg(long)]
+    yes: bool,
+    #[command(flatten)]
+    socket: ControllerSocketArg,
+}
+
 #[derive(Args)]
 struct AgentCreateArgs {
     /// Name for the new agent: 1–63 characters of `[a-z0-9-]`.
@@ -690,6 +720,12 @@ fn main() -> Result<()> {
             let target = remote.target(args.controller_socket)?;
             agent::mint_forge_token(&target, &args.name)
         }
+        Verb::Agent {
+            command: AgentVerb::SetState(args),
+        } => {
+            let target = args.socket.resolve(&remote)?;
+            agent::set_state(&target, &args.agent, &args.hive, args.state, args.yes)
+        }
         Verb::Agent {
             command: AgentVerb::Inference { command },
         } => inference(&remote, command),
@@ -1265,6 +1301,40 @@ fn open_new_nofollow(tmp: &Path) -> io::Result<File> {
 mod tests {
     use super::*;
 
+    #[test]
+    fn set_state_takes_the_wire_enum_values() {
+        let cli = Cli::try_parse_from([
+            "swarmctl",
+            "agent",
+            "set-state",
+            "iris",
+            "--hive",
+            "alpha",
+            "paused",
+        ])
+        .expect("parses");
+        let Verb::Agent {
+            command: AgentVerb::SetState(args),
+        } = cli.command
+        else {
+            panic!("parsed as another verb");
+        };
+        assert_eq!(args.state, swarm_wire::wanted::AgentState::Paused);
+        assert!(!args.yes);
+        assert!(
+            Cli::try_parse_from([
+                "swarmctl",
+                "agent",
+                "set-state",
+                "iris",
+                "--hive",
+                "alpha",
+                "sleeping",
+            ])
+            .is_err()
+        );
+    }
+
     /// Root on the controller host, with no `--swarm` and no login: the verbs
     /// still go over the unix socket, unchanged by the remote path.
     #[test]