feat: add a new .recover command for sessions to recover from errors

src/config/input.rs

@@ -321,6 +321,10 @@ impl Input {
         }
     }
 
+    pub fn with_session(&self) -> bool {
+        self.with_session
+    }
+
     pub fn with_agent(&self) -> bool {
         self.with_agent
     }

src/config/request_context.rs

@@ -728,6 +728,26 @@ impl RequestContext {
         Ok(())
     }
 
+    pub fn on_chat_completion_error(&mut self, app: &AppConfig, input: &Input) {
+        self.last_message = Some(LastMessage::new(input.clone(), String::new()));
+        if input.session(&self.session).is_none() {
+            if let Some(lm) = self.last_message.as_mut() {
+                lm.continuous = false;
+            }
+
+            return;
+        }
+
+        let mut i = input.clone();
+        i.clear_patch();
+        if let Some(session) = i.session_mut(&mut self.session) {
+            let _ = session.add_message(&i, "[Response interrupted due to error]");
+            if !app.dry_run && session.save_session() == Some(true) {
+                let _ = session.flush();
+            }
+        }
+    }
+
     pub fn discontinuous_last_message(&mut self) {
         if let Some(last_message) = self.last_message.as_mut() {
             last_message.continuous = false;
@@ -5424,6 +5444,54 @@ mod tests {
         assert!(lm.continuous);
     }
 
+    #[test]
+    fn on_chat_completion_error_without_session_sets_last_message_discontinuous() {
+        let mut ctx = create_test_ctx();
+        let app = Arc::clone(&ctx.app.config);
+        let input = Input::from_str(&ctx, "hello", None).unwrap();
+
+        ctx.on_chat_completion_error(app.as_ref(), &input);
+
+        let lm = ctx.last_message.as_ref().unwrap();
+        assert_eq!(lm.output, "");
+        assert!(!lm.continuous, "no session means recovery is not possible");
+    }
+
+    #[test]
+    fn on_chat_completion_error_with_session_sets_last_message_continuous() {
+        let mut ctx = create_test_ctx();
+        ctx.app = Arc::new(AppState {
+            config: Arc::new(AppConfig {
+                dry_run: true,
+                ..(*ctx.app.config).clone()
+            }),
+            ..(*ctx.app).clone()
+        });
+        ctx.session = Some(Session::default());
+        let app = Arc::clone(&ctx.app.config);
+        let input = Input::from_str(&ctx, "hello", None).unwrap();
+
+        ctx.on_chat_completion_error(app.as_ref(), &input);
+
+        let lm = ctx.last_message.as_ref().unwrap();
+        assert_eq!(lm.output, "");
+        assert!(lm.continuous, "session present means .recover is available");
+    }
+
+    #[test]
+    fn on_chat_completion_error_with_session_checkpoints_session_messages() {
+        let mut ctx = create_test_ctx();
+        ctx.session = Some(Session::default());
+        assert!(ctx.session.as_ref().unwrap().is_empty());
+        let app = Arc::clone(&ctx.app.config);
+        let input = Input::from_str(&ctx, "hello", None).unwrap();
+        ctx.on_chat_completion_error(app.as_ref(), &input);
+        assert!(
+            !ctx.session.as_ref().unwrap().is_empty(),
+            "session should have the interrupted turn checkpointed"
+        );
+    }
+
     #[test]
     fn after_chat_completion_sweeps_auto_unload_skills_at_turn_end() {
         let mut ctx = create_test_ctx();

src/config/session.rs

@@ -699,6 +699,19 @@ impl Session {
         Ok(())
     }
 
+    pub fn flush(&mut self) -> Result<()> {
+        if !self.dirty {
+            return Ok(());
+        }
+
+        if let Some(path) = self.path.clone() {
+            let name = self.name.clone();
+            self.save(&name, Path::new(&path), false)?;
+        }
+
+        Ok(())
+    }
+
     pub fn guard_empty(&self) -> Result<()> {
         if !self.is_empty() {
             bail!(

src/repl/mod.rs

@@ -53,7 +53,7 @@ pub const DEFAULT_CONTINUATION_PROMPT: &str = indoc! {"
     4. Continue with the next pending item now. Call tools immediately."
 };
 
-static REPL_COMMANDS: LazyLock<[ReplCommand; 58]> = LazyLock::new(|| {
+static REPL_COMMANDS: LazyLock<[ReplCommand; 59]> = LazyLock::new(|| {
     [
         ReplCommand::new(".help", "Show this help guide", AssertState::pass()),
         ReplCommand::new(".info", "Show system info", AssertState::pass()),
@@ -278,6 +278,11 @@ static REPL_COMMANDS: LazyLock<[ReplCommand; 58]> = LazyLock::new(|| {
             "Continue previous response",
             AssertState::pass(),
         ),
+        ReplCommand::new(
+            ".recover",
+            "Recover interrupted session after API error or Ctrl+C",
+            AssertState::pass(),
+        ),
         ReplCommand::new(
             ".regenerate",
             "Regenerate last response",
@@ -1101,6 +1106,21 @@ pub async fn run_repl_command(
                 input.set_continue_output(&output);
                 ask(ctx, abort_signal.clone(), input, true).await?;
             }
+            ".recover" => {
+                let has_recoverable = ctx
+                    .last_message
+                    .as_ref()
+                    .map(|v| v.continuous && v.input.with_session())
+                    .unwrap_or(false);
+                if !has_recoverable {
+                    bail!("Unable to recover: no interrupted session response to recover from");
+                }
+                let recovery_text = args
+                    .unwrap_or("Please continue from where you left off.")
+                    .to_string();
+                let recovery_input = Input::from_str(ctx, &recovery_text, None)?;
+                ask(ctx, abort_signal.clone(), recovery_input, false).await?;
+            }
             ".regenerate" => {
                 let LastMessage { mut input, .. } =
                     match ctx.last_message.as_ref().filter(|v| v.continuous).cloned() {
@@ -1307,8 +1327,10 @@ async fn ask(
 
     let client = input.create_client()?;
     ctx.before_chat_completion(&input)?;
-    let (output, tool_results) = if input.stream() {
-        call_chat_completions_streaming(&input, client.as_ref(), ctx, abort_signal.clone()).await?
+    let (output, tool_results) = {
+        let result = if input.stream() {
+            call_chat_completions_streaming(&input, client.as_ref(), ctx, abort_signal.clone())
+                .await
         } else {
             call_chat_completions(
                 &input,
@@ -1318,7 +1340,15 @@ async fn ask(
                 ctx,
                 abort_signal.clone(),
             )
-        .await?
+            .await
+        };
+        match result {
+            Ok(v) => v,
+            Err(err) => {
+                ctx.on_chat_completion_error(app.as_ref(), &input);
+                return Err(err);
+            }
+        }
     };
     ctx.after_chat_completion(app.as_ref(), &input, &output, &tool_results)?;
     if !tool_results.is_empty() {
@@ -1681,8 +1711,8 @@ mod tests {
     }
 
     #[test]
-    fn repl_commands_has_58_entries() {
-        assert_eq!(REPL_COMMANDS.len(), 58);
+    fn repl_commands_has_59_entries() {
+        assert_eq!(REPL_COMMANDS.len(), 59);
     }
 
     #[test]