fix: harden tool execution under load

README.md

@@ -6,7 +6,7 @@ re-encoding of tool-call data, and [ALMAS](https://arxiv.org/abs/2510.03463) age
 ## Quick start
 
 ```sh
-cargo install --locked --git https://github.com/w0wl0lxd/n00n.git n00n
+cargo install --locked --git https://github.com/w0wl0lxd/n00n.git n00n n00n-git n00n-smell
 
 cd your-project && n00n
 ```

changelog.d/388.changed.md

@@ -0,0 +1 @@
+Reduced tool-output update overhead under load and capped batch fan-out at four calls.

changelog.d/388.fixed.md

@@ -0,0 +1 @@
+Fixed discovered nested model specs being rejected when selected and kept bursty shell output responsive without spawning timer processes.

n00n-agent/src/agent/compaction.rs

@@ -82,8 +82,11 @@ pub(super) async fn compact_history(
     session_id: Option<&n00n_storage::id::SessionRef>,
     cwd: &std::path::Path,
     transcript_path: Option<&std::path::Path>,
+    run_hooks: bool,
 ) -> Result<(TokenUsage, String), AgentError> {
-    run_precompact_hooks(trigger, session_id, cwd, transcript_path).await?;
+    if run_hooks {
+        run_precompact_hooks(trigger, session_id, cwd, transcript_path).await?;
+    }
 
     let compact_start = Instant::now();
     let mut compaction_history: Vec<Message> = history.as_slice().to_vec();
@@ -162,7 +165,9 @@ pub(super) async fn compact_history(
         .first_text_content()
         .map_or_else(String::new, std::string::ToString::to_string);
 
-    run_postcompact_hooks(trigger, session_id, cwd, transcript_path, &summary).await;
+    if run_hooks {
+        run_postcompact_hooks(trigger, session_id, cwd, transcript_path, &summary).await;
+    }
 
     let usage = finish_compact(response, history, compact_start, model);
     Ok((usage, summary))
@@ -205,6 +210,16 @@ pub async fn compact(
     model: &Model,
     history: &mut History,
     event_tx: &EventSender,
+) -> Result<(), AgentError> {
+    compact_inner(provider, model, history, event_tx, true).await
+}
+
+async fn compact_inner(
+    provider: &dyn n00n_providers::provider::Provider,
+    model: &Model,
+    history: &mut History,
+    event_tx: &EventSender,
+    run_hooks: bool,
 ) -> Result<(), AgentError> {
     let cancel = CancelToken::none();
     let cwd = std::env::current_dir().unwrap_or_else(|_| std::path::PathBuf::from("/"));
@@ -218,6 +233,7 @@ pub async fn compact(
         None,
         &cwd,
         None,
+        run_hooks,
     )
     .await?;
     let context_size = crate::agent::run::estimate_message_tokens(history.as_slice(), &model.id);
@@ -419,11 +435,12 @@ mod tests {
             let (event_tx, event_rx) = flume::unbounded();
             let mut history = History::new(vec![Message::user("before".into())]);
 
-            compact(
+            compact_inner(
                 &*provider,
                 &model,
                 &mut history,
                 &EventSender::new(event_tx, 0),
+                false,
             )
             .await
             .expect("compact should succeed");
@@ -548,11 +565,12 @@ mod tests {
             let (event_tx, event_rx) = flume::unbounded();
             let mut history = History::new(vec![Message::user("before".into())]);
 
-            compact(
+            compact_inner(
                 &*provider,
                 &compact_model,
                 &mut history,
                 &EventSender::new(event_tx, 0),
+                false,
             )
             .await
             .expect("compact should succeed");
@@ -589,11 +607,12 @@ mod tests {
                 },
             ]);
 
-            compact(
+            compact_inner(
                 &*provider,
                 &model,
                 &mut history,
                 &EventSender::new(raw_tx, 0),
+                false,
             )
             .await
             .unwrap();
@@ -885,11 +904,12 @@ mod tests {
                 },
             ]);
 
-            compact(
+            compact_inner(
                 &*provider,
                 &model,
                 &mut history,
                 &EventSender::new(raw_tx, 0),
+                false,
             )
             .await
             .unwrap();
@@ -1275,6 +1295,7 @@ mod tests {
                 None,
                 &std::env::current_dir().unwrap(),
                 None,
+                false,
             )
             .await;
 
@@ -1327,6 +1348,7 @@ mod tests {
                 None,
                 &std::env::current_dir().unwrap(),
                 None,
+                false,
             )
             .await;
 

n00n-agent/src/agent/run.rs

@@ -171,6 +171,12 @@ pub struct AgentRunParams<'h> {
     pub tool_filter: ToolFilter,
 }
 
+#[cfg(test)]
+enum TestCompactionHooks {
+    Enabled,
+    Disabled,
+}
+
 pub struct Agent<'h> {
     provider: Arc<dyn Provider>,
     model: Arc<Model>,
@@ -188,6 +194,8 @@ pub struct Agent<'h> {
     num_turns: u32,
     recent_calls: RecentCalls,
     auto_compact: bool,
+    #[cfg(test)]
+    test_compaction_hooks: TestCompactionHooks,
     loaded_instructions: LoadedInstructions,
     pre_dispatch_rollback_len: Option<usize>,
     rollback_len: Option<usize>,
@@ -258,6 +266,8 @@ impl<'h> Agent<'h> {
             num_turns: 0,
             recent_calls: RecentCalls::new(),
             auto_compact: compaction::auto_compact_enabled(),
+            #[cfg(test)]
+            test_compaction_hooks: TestCompactionHooks::Enabled,
             loaded_instructions: LoadedInstructions::new(),
             pre_dispatch_rollback_len: None,
             rollback_len: None,
@@ -1152,6 +1162,10 @@ impl<'h> Agent<'h> {
             self.openai_options,
         );
         let cwd = std::env::current_dir().unwrap_or_else(|_| std::path::PathBuf::from("/"));
+        #[cfg(test)]
+        let run_hooks = matches!(self.test_compaction_hooks, TestCompactionHooks::Enabled);
+        #[cfg(not(test))]
+        let run_hooks = true;
         let (usage, summary) = compaction::compact_history(
             &*compact_provider,
             &compact_model,
@@ -1162,6 +1176,7 @@ impl<'h> Agent<'h> {
             self.identity.as_ref().map(SessionIdentity::session_id),
             &cwd,
             None,
+            run_hooks,
         )
         .await?;
         // Charge compaction to the pre-route lane before any Fusion switch.
@@ -2088,7 +2103,7 @@ mod tests {
             },
             false,
         );
-        let agent = Agent::new(
+        let mut agent = Agent::new(
             AgentParams {
                 provider: Arc::new(provider),
                 model: default_model(),
@@ -2120,6 +2135,7 @@ mod tests {
                 tool_filter: filter,
             },
         );
+        agent.test_compaction_hooks = TestCompactionHooks::Disabled;
         (agent, event_rx)
     }