Store preferences by model profile

src/settings.rs

@@ -380,7 +380,9 @@ pub(crate) struct EngineDiagnosticSettings {
 #[serde(default, deny_unknown_fields)]
 pub(crate) struct RuntimePreferences {
     pub(crate) execution: ExecutionPreferences,
+    #[serde(skip)]
     pub(crate) speculative: SpeculativePreferences,
+    #[serde(skip)]
     pub(crate) ssd: SsdPreferences,
     pub(crate) steering: SteeringPreferences,
     pub(crate) diagnostics: DiagnosticPreferences,
@@ -505,7 +507,7 @@ pub(crate) struct EngineExecutionSettings {
     pub(crate) warm_weights: bool,
 }
 
-#[derive(Clone, Copy, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+#[derive(Clone, Copy, Debug, Default, Deserialize, Eq, Ord, PartialEq, PartialOrd, Serialize)]
 #[serde(rename_all = "lowercase")]
 pub(crate) enum ReasoningMode {
     #[serde(rename = "none")]
@@ -530,22 +532,28 @@ impl fmt::Display for ReasoningMode {
 pub(crate) struct GenerationPreferences {
     pub(crate) context_tokens: i32,
     pub(crate) max_generated_tokens: i32,
+    #[serde(skip_serializing, default = "default_system_prompt")]
     pub(crate) system_prompt: String,
     pub(crate) temperature: Option<f32>,
     pub(crate) top_p: Option<f32>,
     pub(crate) min_p: Option<f32>,
     pub(crate) seed: Option<u64>,
+    #[serde(skip_serializing)]
     pub(crate) reasoning_mode: ReasoningMode,
 }
 
 pub(crate) const DEFAULT_SYSTEM_PROMPT: &str = "You are an expert coding assistant operating inside DS4Server, a local coding agent harness. You help users by reading files, executing commands, editing code, and writing new files.\n\nGuidelines:\n- Be concise in your responses\n- Show file paths clearly when working with files";
 
+fn default_system_prompt() -> String {
+    DEFAULT_SYSTEM_PROMPT.into()
+}
+
 impl Default for GenerationPreferences {
     fn default() -> Self {
         Self {
             context_tokens: 32_768,
             max_generated_tokens: 50_000,
-            system_prompt: DEFAULT_SYSTEM_PROMPT.into(),
+            system_prompt: default_system_prompt(),
             temperature: None,
             top_p: None,
             min_p: None,