feat(agent): add rule-based query classification for automatic model routing

Classify incoming user messages by keyword/pattern and route to the
appropriate model hint automatically, feeding into the existing
RouterProvider. Disabled by default; opt-in via [query_classification]
config section.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/config/mod.rs

@@ -3,13 +3,13 @@ pub mod schema;
 #[allow(unused_imports)]
 pub use schema::{
     AgentConfig, AuditConfig, AutonomyConfig, BrowserComputerUseConfig, BrowserConfig,
-    ChannelsConfig, ComposioConfig, Config, CostConfig, CronConfig, DelegateAgentConfig,
-    DiscordConfig, DockerRuntimeConfig, GatewayConfig, HardwareConfig, HardwareTransport,
-    HeartbeatConfig, HttpRequestConfig, IMessageConfig, IdentityConfig, LarkConfig, MatrixConfig,
-    MemoryConfig, ModelRouteConfig, ObservabilityConfig, PeripheralBoardConfig, PeripheralsConfig,
-    ReliabilityConfig, ResourceLimitsConfig, RuntimeConfig, SandboxBackend, SandboxConfig,
-    SchedulerConfig, SecretsConfig, SecurityConfig, SlackConfig, TelegramConfig, TunnelConfig,
-    WebhookConfig,
+    ChannelsConfig, ClassificationRule, ComposioConfig, Config, CostConfig, CronConfig,
+    DelegateAgentConfig, DiscordConfig, DockerRuntimeConfig, GatewayConfig, HardwareConfig,
+    HardwareTransport, HeartbeatConfig, HttpRequestConfig, IMessageConfig, IdentityConfig,
+    LarkConfig, MatrixConfig, MemoryConfig, ModelRouteConfig, ObservabilityConfig,
+    PeripheralBoardConfig, PeripheralsConfig, QueryClassificationConfig, ReliabilityConfig,
+    ResourceLimitsConfig, RuntimeConfig, SandboxBackend, SandboxConfig, SchedulerConfig,
+    SecretsConfig, SecurityConfig, SlackConfig, TelegramConfig, TunnelConfig, WebhookConfig,
 };
 
 #[cfg(test)]

src/config/schema.rs

@@ -47,6 +47,10 @@ pub struct Config {
     #[serde(default)]
     pub model_routes: Vec<ModelRouteConfig>,
 
+    /// Automatic query classification — maps user messages to model hints.
+    #[serde(default)]
+    pub query_classification: QueryClassificationConfig,
+
     #[serde(default)]
     pub heartbeat: HeartbeatConfig,
 
@@ -1205,6 +1209,40 @@ pub struct ModelRouteConfig {
     pub api_key: Option<String>,
 }
 
+// ── Query Classification ─────────────────────────────────────────
+
+/// Automatic query classification — classifies user messages by keyword/pattern
+/// and routes to the appropriate model hint. Disabled by default.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct QueryClassificationConfig {
+    #[serde(default)]
+    pub enabled: bool,
+    #[serde(default)]
+    pub rules: Vec<ClassificationRule>,
+}
+
+/// A single classification rule mapping message patterns to a model hint.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct ClassificationRule {
+    /// Must match a `[[model_routes]]` hint value.
+    pub hint: String,
+    /// Case-insensitive substring matches.
+    #[serde(default)]
+    pub keywords: Vec<String>,
+    /// Case-sensitive literal matches (for "```", "fn ", etc.).
+    #[serde(default)]
+    pub patterns: Vec<String>,
+    /// Only match if message length >= N chars.
+    #[serde(default)]
+    pub min_length: Option<usize>,
+    /// Only match if message length <= N chars.
+    #[serde(default)]
+    pub max_length: Option<usize>,
+    /// Higher priority rules are checked first.
+    #[serde(default)]
+    pub priority: i32,
+}
+
 // ── Heartbeat ────────────────────────────────────────────────────
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -1740,6 +1778,7 @@ impl Default for Config {
             peripherals: PeripheralsConfig::default(),
             agents: HashMap::new(),
             hardware: HardwareConfig::default(),
+            query_classification: QueryClassificationConfig::default(),
         }
     }
 }