Discard archived session checkpoints

src/app/generation.rs

@@ -613,7 +613,13 @@ impl App {
                     }
                 }
             };
-            let Some(service) = &self.generation_service else {
+            let archived_session = self
+                .projects
+                .iter()
+                .flat_map(|project| &project.sessions)
+                .find(|session| session.id == session_id)
+                .is_some_and(|session| session.state() == SessionState::Archived);
+            let Some(service) = self.generation_service.clone() else {
                 self.error = Some("The model runtime is unavailable.".into());
                 return;
             };
@@ -633,6 +639,13 @@ impl App {
                     return;
                 }
             };
+            if archived_session {
+                self.reload_projects();
+                self.context_notice = Some(
+                    "Rebuilding context: the session was archived and its checkpoint was discarded."
+                        .into(),
+                );
+            }
             let user_id = saved[saved.len() - 2].id;
             self.active_turn
                 .get_or_insert_with(TurnSummary::new)
@@ -1643,6 +1656,12 @@ impl App {
         } else {
             None
         };
+        let archived_session = self
+            .projects
+            .iter()
+            .flat_map(|project| &project.sessions)
+            .find(|session| session.id == session_id)
+            .is_some_and(|session| session.state() == SessionState::Archived);
         let tail_start = message_ids.get(compacted.tail_start).copied();
         let messages = self
             .database
@@ -1659,7 +1678,9 @@ impl App {
             .map_err(|error| format!("Could not save compacted conversation: {error}"))?;
         self.conversation
             .extend(messages.into_iter().map(ChatMessage::from));
-        if let Some(session) = self
+        if archived_session {
+            self.reload_projects();
+        } else if let Some(session) = self
             .projects
             .iter_mut()
             .flat_map(|project| &mut project.sessions)

src/app/projects.rs

@@ -515,6 +515,25 @@ mod tests {
         std::fs::remove_dir_all(directory).unwrap();
     }
 
+    #[test]
+    fn discarding_a_session_removes_every_checkpoint_stage() {
+        let directory =
+            std::env::temp_dir().join(format!("ds4-server-discard-{}", std::process::id()));
+        std::fs::create_dir_all(&directory).unwrap();
+        for name in ["4.bin", "4.tmp", "4.compacting", "5.bin"] {
+            std::fs::write(directory.join(name), b"payload").unwrap();
+        }
+
+        assert!(super::super::discard_session_checkpoint_files(&directory, 4).unwrap());
+        assert!(!directory.join("4.bin").exists());
+        assert!(!directory.join("4.tmp").exists());
+        assert!(!directory.join("4.compacting").exists());
+        assert!(directory.join("5.bin").exists());
+        assert!(!super::super::discard_session_checkpoint_files(&directory, 4).unwrap());
+
+        std::fs::remove_dir_all(directory).unwrap();
+    }
+
     #[test]
     fn git_state_lists_and_switches_local_branches() {
         let nonce = SystemTime::now()