Add persistent local agent tools

src/engine.rs

@@ -319,6 +319,7 @@ pub(crate) struct Generator {
 #[derive(Clone)]
 pub(crate) struct ChatTurn {
     pub(crate) user: bool,
+    pub(crate) tool: bool,
     pub(crate) skip_previous_eos: bool,
     pub(crate) reasoning: Option<String>,
     pub(crate) reasoning_complete: bool,
@@ -571,6 +572,7 @@ impl Generator {
         let mut reasoning = settings.reasoning_mode != ReasoningMode::Direct;
         let mut generated = ChatTurn {
             user: false,
+            tool: false,
             skip_previous_eos: false,
             reasoning: reasoning.then(String::new),
             reasoning_complete: !reasoning,
@@ -896,7 +898,7 @@ fn conversation_key(system: &str, reasoning: ReasoningMode, messages: &[ChatTurn
         output.extend_from_slice(value.as_bytes());
     }
 
-    let mut output = b"DS4Server chat checkpoint v2".to_vec();
+    let mut output = b"DS4Server chat checkpoint v3".to_vec();
     text(&mut output, system);
     output.push(match reasoning {
         ReasoningMode::Direct => 0,
@@ -905,6 +907,7 @@ fn conversation_key(system: &str, reasoning: ReasoningMode, messages: &[ChatTurn
     });
     for message in messages {
         output.push(u8::from(message.user));
+        output.push(u8::from(message.tool));
         output.push(u8::from(message.skip_previous_eos));
         match &message.reasoning {
             Some(reasoning) => {
@@ -1057,6 +1060,7 @@ mod sampling_tests {
     fn split_utf8_token_bytes_are_joined_before_decoding() {
         let mut generated = ChatTurn {
             user: false,
+            tool: false,
             skip_previous_eos: false,
             reasoning: None,
             reasoning_complete: true,
@@ -1076,6 +1080,7 @@ mod sampling_tests {
     fn checkpoint_tag_covers_the_canonical_chat_state() {
         let mut messages = vec![ChatTurn {
             user: true,
+            tool: false,
             skip_previous_eos: false,
             reasoning: None,
             reasoning_complete: true,
@@ -1102,6 +1107,7 @@ mod sampling_tests {
         let prefix = conversation_key("System", ReasoningMode::High, &messages);
         messages.push(ChatTurn {
             user: false,
+            tool: false,
             skip_previous_eos: false,
             reasoning: Some("because".into()),
             reasoning_complete: true,