hive-agent: a logged-in agent polls the swarm login, and logs out when it is deleted

wait_for_login read the store leaf only while the agent waited for a login.
A logged-in agent now reads it every 5 minutes, and a paused one once before
it resumes, so a login made or deleted in the swarm UI reaches an agent that
never failed. A newer version is installed; a store that answers nothing
stored after a version was installed means the stored login was deleted, and
the agent is logged out as /api/logout does it, with the recorded version
forgotten so the next login installs. A read that fails changes nothing.

docs/2-handbook/swarm/claude-login.md

@@ -28,11 +28,13 @@ pins for agents, and its container's own nixpkgs' where the host pins none.
    stores the `.credentials.json` claude wrote at
    `swarm/agents/<agent>/claude-credentials` (field `value`), as a new version
    over any stored before, and removes the scratch directory.
-6. The agent's harness, while it waits for a login, reads that leaf every 30
-   seconds under the agent's own certificate. When the stored version is newer
-   than the one it installed last, it writes the file to
-   `~/.claude/.credentials.json`, records the version, and resumes its turn
-   loop as it does after a login from the agent's web UI.
+6. The agent's harness reads that leaf under the agent's own certificate: every
+   30 seconds while it waits for a login, every 5 minutes while it has a
+   session, and once as a paused agent resumes. When the stored version is
+   newer than the one it installed last, it writes the file to
+   `~/.claude/.credentials.json`, records the version, and, for an agent that
+   waited, resumes its turn loop as it does after a login from the agent's web
+   UI.
 
 A started login waits 15 minutes for its code, then the minter stops it.
 Starting another login for the same agent replaces the running one. Each step
@@ -65,7 +67,11 @@ version it installed (`claude-credentials-version` under the harness dir):
 - it installs a newer version, that is, a new login;
 - it leaves an equal or older version alone, even when the agent needs a
   login again, so it never puts back a session that has gone bad;
-- it reads nothing while the agent has a session.
+- it logs the agent out when the store holds nothing although a version was
+  installed: the operator deleted the stored login. A read that failed never
+  does it, since an unreachable store says nothing about the login. The
+  logout is the one `/api/logout` does, and the recorded version is
+  forgotten so the next login installs.
 
 ## Credentials
 

hive-agent/src/claude_credentials.rs

@@ -1,6 +1,7 @@
 //! The claude credentials the swarm's login minter stored for this agent, at
 //! `swarm/agents/<agent>/claude-credentials`, read under the agent's own
-//! certificate while it waits for a login ([`crate::login::wait_for_login`]).
+//! certificate while it waits for a login ([`crate::login::wait_for_login`]),
+//! and every few minutes while it runs ([`crate::login_watch`]).
 //!
 //! ⚠️ **Installed only when the store's version is newer than the last one
 //! installed here**, never because the bytes differ. `claude` rotates the
@@ -9,6 +10,10 @@
 //! The last installed version is kept in [`VERSION_FILE`] under the harness
 //! dir. A credentials file `wait_for_login` sees land resumes the agent as a
 //! web-UI login does.
+//!
+//! A store that answers "nothing stored" after a version was installed here
+//! means the operator deleted the stored login ([`Outcome::Deleted`]); a store
+//! that does not answer is an error and means nothing.
 
 use std::future::Future;
 use std::path::{Path, PathBuf};
@@ -43,8 +48,12 @@ pub fn is_newer(stored: u64, installed: Option<u64>) -> bool {
 /// What one [`Pickup::check`] did.
 #[derive(Debug, PartialEq, Eq)]
 pub enum Outcome {
-    /// Nothing is stored for this agent.
+    /// Nothing is stored for this agent, and no version was ever installed
+    /// here: no swarm login has reached this agent.
     NothingStored,
+    /// The store answered that nothing is stored, though version `installed`
+    /// was installed here: the operator deleted the stored login.
+    Deleted { installed: u64 },
     /// The stored version is not newer than the installed one.
     NotNewer { stored: u64, installed: u64 },
     /// The stored version is installed now.
@@ -120,7 +129,10 @@ impl<S: Source> Pickup<S> {
     /// The store read failed, or writing the credentials or the version did.
     pub async fn check(&self) -> anyhow::Result<Outcome> {
         let Some((credentials, stored)) = self.source.fetch().await? else {
-            return Ok(Outcome::NothingStored);
+            return Ok(match read_version(&self.version_file)? {
+                Some(installed) => Outcome::Deleted { installed },
+                None => Outcome::NothingStored,
+            });
         };
         let installed = read_version(&self.version_file)?;
         if !is_newer(stored, installed) {
@@ -138,6 +150,19 @@ impl<S: Source> Pickup<S> {
             .context("recording the installed credentials version")?;
         Ok(Outcome::Installed { version: stored })
     }
+
+    /// Forget the installed version, once the deletion it showed has been
+    /// acted on, so the next login installs whatever version it gets.
+    ///
+    /// # Errors
+    /// Removing the version file failed for a reason other than its absence.
+    pub fn forget_installed(&self) -> anyhow::Result<()> {
+        match std::fs::remove_file(&self.version_file) {
+            Ok(()) => Ok(()),
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(()),
+            Err(e) => Err(e).with_context(|| format!("removing {}", self.version_file.display())),
+        }
+    }
 }
 
 /// The version recorded in `file`, or `None` when there is no file.
@@ -302,4 +327,50 @@ mod tests {
         assert_eq!(installed(&d), None);
         assert_eq!(read_version(&d.0.join(VERSION_FILE)).expect("read"), None);
     }
+
+    #[tokio::test]
+    async fn a_login_deleted_after_an_install_is_reported_and_forgotten_on_request() {
+        let d = dir("deleted");
+        let p = pickup(&d, Some(("{\"v\":1}", 1)));
+        p.check().await.expect("install");
+        *p.source.0.lock().expect("lock") = None;
+        assert_eq!(
+            p.check().await.expect("check"),
+            Outcome::Deleted { installed: 1 }
+        );
+        // Reporting it changes nothing: the caller acts, then forgets.
+        assert_eq!(
+            p.check().await.expect("check again"),
+            Outcome::Deleted { installed: 1 }
+        );
+        p.forget_installed().expect("forget");
+        p.forget_installed().expect("forgetting twice is fine");
+        assert_eq!(p.check().await.expect("check"), Outcome::NothingStored);
+        *p.source.0.lock().expect("lock") = Some(("{\"v\":1}".to_owned(), 1));
+        assert_eq!(
+            p.check().await.expect("a new login"),
+            Outcome::Installed { version: 1 },
+            "the counter restarts after a delete, and its first login still installs"
+        );
+    }
+
+    struct Failing;
+
+    impl Source for Failing {
+        async fn fetch(&self) -> anyhow::Result<Option<(Credentials, u64)>> {
+            anyhow::bail!("the store did not answer")
+        }
+    }
+
+    #[tokio::test]
+    async fn a_failed_read_is_an_error_never_a_deletion() {
+        let d = dir("failing");
+        std::fs::write(d.0.join(VERSION_FILE), "4").expect("an installed version");
+        let p = Pickup::new(Failing, d.0.join("claude"), d.0.join(VERSION_FILE));
+        assert!(p.check().await.is_err());
+        assert_eq!(
+            read_version(&d.0.join(VERSION_FILE)).expect("read"),
+            Some(4)
+        );
+    }
 }

hive-agent/src/login.rs

@@ -191,6 +191,14 @@ pub async fn wait_for_login(
                     version,
                     "installed the claude credentials the swarm login stored"
                 ),
+                Ok(claude_credentials::Outcome::Deleted { installed }) => {
+                    // Nothing to log out of, but the recorded version would
+                    // keep a restarted counter's first login from installing.
+                    tracing::info!(installed, "the swarm's stored claude login was deleted");
+                    if let Err(e) = pickup.forget_installed() {
+                        tracing::warn!(error = %format!("{e:#}"), "forgetting the installed login version failed");
+                    }
+                }
                 Ok(outcome) => tracing::debug!(?outcome, "no newer swarm claude credentials"),
                 Err(e) => tracing::warn!(
                     error = %format!("{e:#}"),
@@ -214,7 +222,7 @@ pub async fn wait_for_login(
 
 /// The swarm-login pickup for `claude_dir`, or `None` when this process has
 /// no store to read from.
-fn swarm_pickup(
+pub(crate) fn swarm_pickup(
     claude_dir: &Path,
 ) -> Option<claude_credentials::Pickup<claude_credentials::Store>> {
     match claude_credentials::Store::from_env() {

hive-agent/src/login_watch.rs

@@ -0,0 +1,72 @@
+//! The swarm login, watched while the agent runs. [`crate::login::wait_for_login`]
+//! reads the agent's store leaf while the agent waits for a login; this reads
+//! it every [`POLL_INTERVAL`] while the agent is logged in, and once more just
+//! before a paused agent resumes, so a login the operator made or deleted in
+//! the swarm UI reaches an agent that never failed.
+//!
+//! - A newer stored version is installed over the session, as after a login
+//!   while waiting ([`crate::claude_credentials`]).
+//! - A store that answers "nothing stored" after a version was installed here
+//!   means the operator deleted the stored login: the agent is logged out as
+//!   `/api/logout` does it, and the recorded version is forgotten so the next
+//!   login installs.
+//! - A read that fails does nothing. A store that cannot be reached says
+//!   nothing about the login, and logging out on it would turn a store restart
+//!   into an outage of every agent.
+
+use std::time::Duration;
+
+use crate::claude_credentials::Outcome;
+use crate::events::{Bus, LiveEvent};
+use crate::login::{self, LoginState};
+use crate::web_ui::{LoginStateCell, force_logout};
+
+/// How often a logged-in agent asks the store.
+pub const POLL_INTERVAL: Duration = Duration::from_mins(5);
+
+/// Check the store every [`POLL_INTERVAL`], for the life of the process.
+pub async fn run(login: LoginStateCell, bus: Bus) {
+    let mut tick = tokio::time::interval(POLL_INTERVAL);
+    tick.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Delay);
+    // The first tick is immediate; the boot path has read the store already.
+    tick.tick().await;
+    loop {
+        tick.tick().await;
+        check_once(&login, &bus).await;
+    }
+}
+
+/// Read the store once for a logged-in agent and act on what it holds. Does
+/// nothing for an agent waiting for a login, which polls for itself.
+///
+/// # Panics
+///
+/// Panics if the login-state lock is poisoned.
+pub async fn check_once(login: &LoginStateCell, bus: &Bus) {
+    if *login.lock().unwrap() != LoginState::Online {
+        return;
+    }
+    let Some(pickup) = login::swarm_pickup(&crate::paths::claude_dir()) else {
+        return;
+    };
+    match pickup.check().await {
+        Ok(Outcome::Installed { version }) => {
+            tracing::info!(version, "installed a newer swarm claude login");
+            bus.emit(LiveEvent::Note {
+                text: format!("swarm login: installed version {version} over the running session"),
+            });
+        }
+        Ok(Outcome::Deleted { installed }) => {
+            tracing::info!(installed, "the swarm's stored claude login was deleted");
+            force_logout(login, bus, "swarm login deleted").await;
+            if let Err(e) = pickup.forget_installed() {
+                tracing::warn!(error = %format!("{e:#}"), "forgetting the installed login version failed");
+            }
+        }
+        Ok(outcome) => tracing::debug!(?outcome, "no change in the swarm claude login"),
+        Err(e) => tracing::warn!(
+            error = %format!("{e:#}"),
+            "checking the swarm store for a claude login failed; leaving the session alone"
+        ),
+    }
+}

hive-agent/src/main.rs

@@ -20,6 +20,7 @@ mod events;
 mod harness_state;
 mod identity;
 mod login;
+mod login_watch;
 mod mcp_config;
 mod otel_turn_metrics;
 mod paths;
@@ -540,6 +541,7 @@ async fn serve_main<S: Surface>(socket: &Path, poll_ms: u64) -> Result<()> {
     // hive-c0re, because the files are agent-owned — see `vacuum` module docs.
     tokio::spawn(crate::vacuum::run());
     tokio::spawn(claude_usage_watch::run());
+    tokio::spawn(login_watch::run(login_state.clone(), bus.clone()));
     tokio::spawn(subagent_role_watch::run());
     // Log web_ui::serve's error instead of dropping it. A bare
     // `tokio::spawn(web_ui::serve(...))` discards the JoinHandle, so
@@ -780,6 +782,9 @@ async fn serve_loop<S: Surface>(
             });
             was_paused = false;
             todo_miss_streak = 0;
+            // A login the operator deleted or renewed while the agent was parked
+            // counts before its first turn, not five minutes into it.
+            login_watch::check_once(&login_state, &bus).await;
         }
         let next = match next_outcome(
             S::recv_next(socket),

hive-agent/src/web_ui/auth.rs

@@ -6,9 +6,10 @@ use axum::{
     response::{IntoResponse, Response},
 };
 
+use crate::events::Bus;
 use crate::login::LoginState;
 
-use super::AppState;
+use super::{AppState, LoginStateCell};
 
 /// Operator-driven `/logout`: SIGINT claude, delete the credential
 /// files (via [`crate::login::clear_session`]), flip `LoginState::NeedsLogin`.
@@ -20,6 +21,13 @@ use super::AppState;
 /// (the `/api/logout` bullet) for the three-step rationale +
 /// preservation invariants.
 pub(super) async fn post_logout(State(state): State<AppState>) -> Response {
+    let said = force_logout(&state.login, &state.bus, "operator: /logout").await;
+    (axum::http::StatusCode::OK, format!("ok: {said}")).into_response()
+}
+
+/// The three steps of a logout, shared by `/api/logout` and the swarm login
+/// watch: `by` heads the Note. Returns what was wiped, for the response.
+pub(crate) async fn force_logout(login: &LoginStateCell, bus: &Bus, by: &str) -> String {
     // Step 1: SIGINT claude (best-effort, matches `post_cancel_turn`).
     let _ = super::sigint_claude();
     // Step 2: delete OAuth credential files only — login::clear_session owns
@@ -34,19 +42,13 @@ pub(super) async fn post_logout(State(state): State<AppState>) -> Response {
     };
     // Step 3: flip LoginState + emit Note. Turn loop sees the flip on
     // its next iteration and parks into wait_for_login.
-    *state.login.lock().unwrap() = LoginState::NeedsLogin;
-    state.bus.emit(crate::events::LiveEvent::Note {
-        text: format!(
-            "operator: /logout — {wipe_summary} in {}{warn_suffix}",
-            dir.display()
-        ),
+    *login.lock().unwrap() = LoginState::NeedsLogin;
+    let said = format!("{wipe_summary} in {}{warn_suffix}", dir.display());
+    bus.emit(crate::events::LiveEvent::Note {
+        text: format!("{by} — {said}"),
     });
-    state.bus.emit_status("needs_login_idle");
-    (
-        axum::http::StatusCode::OK,
-        format!("ok: {wipe_summary} in {}{warn_suffix}", dir.display()),
-    )
-        .into_response()
+    bus.emit_status("needs_login_idle");
+    said
 }
 
 /// Human-readable summary of a [`crate::login::ClearedSession`] outcome for

hive-agent/src/web_ui/mod.rs

@@ -11,6 +11,7 @@
 
 mod actions;
 mod auth;
+pub(crate) use auth::force_logout;
 mod proxy;
 mod screen;
 mod state;