swarm-controller: archive a destroyed agent's config repo, unarchive it when the name is created again

swarm-controller/src/agent_config_repo.rs

@@ -0,0 +1,36 @@
+//! A destroyed agent's config repo (`agent-configs/<agent>`): archived when the
+//! agent is declared `Destroyed`, so it stays readable but takes no more
+//! pushes or PRs, and unarchived when an agent of the same name is created
+//! again (`forge::Client::create_repo`).
+
+use crate::routes::AppState;
+
+/// Archive `agent`'s config repo. A failure is logged and does not stop the
+/// destroy, as in `agent_archetype::clear_on_destroy`: an agent that cannot be
+/// torn down is the larger harm, and declaring it destroyed again re-runs
+/// this.
+pub(crate) async fn archive_on_destroy(state: &AppState, hive: &str, agent: &str) {
+    let Some(forge) = state.forge.get() else {
+        tracing::warn!(
+            hive,
+            agent,
+            "no forge access here, so the destroyed agent's config repo was left as it is"
+        );
+        return;
+    };
+    match forge.set_config_repo_archived(agent, true).await {
+        Ok(true) => tracing::info!(hive, agent, "destroyed agent's config repo archived"),
+        Ok(false) => tracing::debug!(
+            hive,
+            agent,
+            "destroyed agent's config repo was already archived, or does not exist"
+        ),
+        Err(e) => tracing::error!(
+            hive,
+            agent,
+            error = %format!("{e:#}"),
+            "archiving this agent's config repo FAILED; it was destroyed anyway, so the repo \
+             still takes pushes. Declaring the agent destroyed again re-runs this."
+        ),
+    }
+}

swarm-controller/src/forge.rs

@@ -669,14 +669,55 @@ impl Client {
     /// Ensures the org and its [`OPERATORS_TEAM`] first: the periodic
     /// [`objects`] pass does too, but an agent can be created before that
     /// pass has succeeded once, and the rule below names the team.
+    ///
+    /// An archived repo, left by an earlier agent of the same name that was
+    /// destroyed ([`Self::set_config_repo_archived`]), is unarchived before the
+    /// rule is applied: an archived repo refuses every write.
     pub async fn create_repo(&self, repo: &str) -> Result<String> {
         self.ensure_merge_gate_prerequisites().await?;
         self.ensure_org_repo(repo).await?;
+        self.set_config_repo_archived(repo, false).await?;
         self.apply_operator_branch_protection(repo).await?;
         tracing::info!(%repo, "swarm forge: created repo in {CONFIG_ORG} with operator merge gate");
         Ok(format!("{CONFIG_ORG}/{repo}"))
     }
 
+    /// Archive or unarchive `repo` in [`CONFIG_ORG`]: read-only while archived,
+    /// so a destroyed agent's config can no longer be pushed to or have PRs
+    /// opened against it, and it stays readable.
+    ///
+    /// Returns whether anything changed. A repo already in the requested state
+    /// and a repo that does not exist both return `false`: destroying an agent
+    /// that never got a config repo is not a fault, and a repeated destroy is
+    /// ordinary.
+    ///
+    /// # Errors
+    /// A forge failure reading the repo or editing it.
+    pub async fn set_config_repo_archived(&self, repo: &str, archived: bool) -> Result<bool> {
+        let current = match self
+            .api
+            .call(|api| api.repo_get(CONFIG_ORG, repo).into_future())
+            .await
+        {
+            Ok(r) => r.archived.unwrap_or(false),
+            Err(e) if is_repo_not_found(&e) => return Ok(false),
+            Err(e) => return Err(e).with_context(|| format!("get repo {CONFIG_ORG}/{repo}")),
+        };
+        if current == archived {
+            return Ok(false);
+        }
+        let mut edit = objects::sparse_edit_repo_option();
+        edit.archived = Some(archived);
+        self.api
+            .call(|api| api.repo_edit(CONFIG_ORG, repo, edit.clone()).into_future())
+            .await
+            .with_context(|| {
+                let verb = if archived { "archive" } else { "unarchive" };
+                format!("{verb} repo {CONFIG_ORG}/{repo}")
+            })?;
+        Ok(true)
+    }
+
     /// Add `agent` as a **write** collaborator on `repo` (can push + open
     /// PRs, cannot bypass branch protection) — the whole job of the
     /// `AddRepoMember` node. Idempotent.
@@ -2273,6 +2314,112 @@ impl Client {
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    /// A stand-in forge holding `agent-configs/atlas`, archived or not, that
+    /// records each PATCH body and flips the flag when it receives one. Any
+    /// other repo is a 404.
+    async fn config_repo_forge(
+        archived: bool,
+    ) -> (Client, Arc<std::sync::Mutex<Vec<serde_json::Value>>>) {
+        use axum::http::{Method, Uri};
+
+        let edits = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let state = Arc::new(std::sync::Mutex::new(archived));
+        let (seen, flag) = (Arc::clone(&edits), Arc::clone(&state));
+        let app = axum::Router::new().fallback(
+            move |method: Method, uri: Uri, body: axum::body::Bytes| {
+                let (seen, flag) = (Arc::clone(&seen), Arc::clone(&flag));
+                async move {
+                    if uri.path() != "/api/v1/repos/agent-configs/atlas" {
+                        return (StatusCode::NOT_FOUND, r#"{"message":"no"}"#.to_owned());
+                    }
+                    if method == axum::http::Method::PATCH {
+                        let edit: serde_json::Value = serde_json::from_slice(&body).unwrap();
+                        if let Some(now) = edit["archived"].as_bool() {
+                            *flag.lock().unwrap() = now;
+                        }
+                        // The client sends every unset field as `null`, which the
+                        // forge reads as "leave alone"; keep what is actually set.
+                        let set: serde_json::Map<_, _> = edit
+                            .as_object()
+                            .unwrap()
+                            .iter()
+                            .filter(|(_, v)| !v.is_null())
+                            .map(|(k, v)| (k.clone(), v.clone()))
+                            .collect();
+                        seen.lock().unwrap().push(serde_json::Value::Object(set));
+                    }
+                    let archived = *flag.lock().unwrap();
+                    (
+                        StatusCode::OK,
+                        format!(r#"{{"name":"atlas","archived":{archived}}}"#),
+                    )
+                }
+            },
+        );
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let url = url::Url::parse(&format!("http://{}/", listener.local_addr().unwrap())).unwrap();
+        tokio::spawn(async move { axum::serve(listener, app).await });
+        (Client::for_test_forge(url), edits)
+    }
+
+    #[tokio::test]
+    async fn a_destroyed_agents_config_repo_is_archived_once() {
+        let (client, edits) = config_repo_forge(false).await;
+        assert!(
+            client
+                .set_config_repo_archived("atlas", true)
+                .await
+                .unwrap()
+        );
+        assert_eq!(
+            *edits.lock().unwrap(),
+            [serde_json::json!({"archived": true})],
+            "one edit, touching nothing but the flag"
+        );
+        assert!(
+            !client
+                .set_config_repo_archived("atlas", true)
+                .await
+                .unwrap(),
+            "a repeated destroy changes nothing"
+        );
+        assert_eq!(edits.lock().unwrap().len(), 1, "and sends no second edit");
+    }
+
+    #[tokio::test]
+    async fn a_new_agent_of_the_same_name_gets_its_repo_unarchived() {
+        let (client, edits) = config_repo_forge(true).await;
+        assert!(
+            client
+                .set_config_repo_archived("atlas", false)
+                .await
+                .unwrap()
+        );
+        assert_eq!(
+            *edits.lock().unwrap(),
+            [serde_json::json!({"archived": false})]
+        );
+        assert!(
+            !client
+                .set_config_repo_archived("atlas", false)
+                .await
+                .unwrap()
+        );
+    }
+
+    #[tokio::test]
+    async fn an_agent_without_a_config_repo_is_not_an_error_to_archive() {
+        let (client, edits) = config_repo_forge(false).await;
+        assert!(
+            !client
+                .set_config_repo_archived("ghost", true)
+                .await
+                .unwrap()
+        );
+        assert!(edits.lock().unwrap().is_empty());
+    }
+
     /// Commit stats sum per side; a commit with none, or a negative figure,
     /// adds zero.
     #[test]

swarm-controller/src/forge/objects.rs

@@ -594,7 +594,7 @@ fn seen<T, U>(res: Result<T, ForgejoError>, what: &str, f: impl FnOnce(T) -> U)
 
 /// `EditRepoOption` with every field unset — repo edits only ever change the
 /// one field the caller sets on top (Forgejo leaves `None` fields untouched).
-fn sparse_edit_repo_option() -> EditRepoOption {
+pub(super) fn sparse_edit_repo_option() -> EditRepoOption {
     EditRepoOption {
         allow_fast_forward_only_merge: None,
         allow_manual_merge: None,
@@ -728,7 +728,13 @@ impl Client {
                 return;
             }
         };
-        for name in repos.into_iter().filter_map(|r| r.name) {
+        // An archived repo is a destroyed agent's, and refuses every write, so
+        // converging its rule would fail on each pass for as long as it stays.
+        for name in repos
+            .into_iter()
+            .filter(|r| !r.archived.unwrap_or(false))
+            .filter_map(|r| r.name)
+        {
             let rule = seen(
                 self.api
                     .call(|api| {

swarm-controller/src/main.rs

@@ -22,6 +22,7 @@ use std::sync::{Arc, Mutex};
 use anyhow::{Context, Result};
 
 mod agent_archetype;
+mod agent_config_repo;
 mod agent_control;
 mod agent_custom;
 mod agent_entity;

swarm-controller/src/routes/agents.rs

@@ -219,6 +219,7 @@ pub(crate) async fn set_agent_state(
         agents_md_initial::clear_on_destroy(&state, &hive, &agent).await;
         egress_allow::clear_on_destroy(&state, &hive, &agent).await;
         egress_deny::clear_on_destroy(&state, &hive, &agent).await;
+        crate::agent_config_repo::archive_on_destroy(&state, &hive, &agent).await;
     }
     Ok(Json(render(&declaration)))
 }