Add hybrid text plus vector memory search

src/config.rs

@@ -11,6 +11,7 @@ pub struct Config {
     pub server: ServerConfig,
     pub database: DatabaseConfig,
     pub embedding: EmbeddingConfig,
+    pub query: QueryConfig,
     pub auth: AuthConfig,
 }
 
@@ -45,6 +46,15 @@ pub struct EmbeddingConfig {
     pub dimension: usize,
 }
 
+/// Query scoring configuration
+#[derive(Debug, Clone, Deserialize)]
+pub struct QueryConfig {
+    #[serde(default = "default_vector_weight")]
+    pub vector_weight: f32,
+    #[serde(default = "default_text_weight")]
+    pub text_weight: f32,
+}
+
 /// Authentication configuration
 #[derive(Debug, Clone, Deserialize)]
 pub struct AuthConfig {
@@ -86,6 +96,8 @@ fn default_db_port() -> u16 { 5432 }
 fn default_pool_size() -> usize { 10 }
 fn default_model_path() -> String { "models/all-MiniLM-L6-v2".to_string() }
 fn default_embedding_dim() -> usize { 384 }
+fn default_vector_weight() -> f32 { 0.6 }
+fn default_text_weight() -> f32 { 0.4 }
 fn default_auth_enabled() -> bool { false }
 
 impl Config {
@@ -104,6 +116,9 @@ impl Config {
             // Embedding settings
             .set_default("embedding.model_path", default_model_path())?
             .set_default("embedding.dimension", default_embedding_dim() as i64)?
+            // Query settings
+            .set_default("query.vector_weight", default_vector_weight() as f64)?
+            .set_default("query.text_weight", default_text_weight() as f64)?
             // Auth settings
             .set_default("auth.enabled", default_auth_enabled())?
             // Load from environment with OPENBRAIN_ prefix
@@ -114,7 +129,21 @@ impl Config {
             )
             .build()?;
 
-        Ok(config.try_deserialize()?)
+        let mut config: Self = config.try_deserialize()?;
+
+        // Keep compatibility with plain env names proposed in issue #17.
+        if let Ok(vector_weight) = std::env::var("VECTOR_WEIGHT") {
+            if let Ok(parsed) = vector_weight.parse::<f32>() {
+                config.query.vector_weight = parsed;
+            }
+        }
+        if let Ok(text_weight) = std::env::var("TEXT_WEIGHT") {
+            if let Ok(parsed) = text_weight.parse::<f32>() {
+                config.query.text_weight = parsed;
+            }
+        }
+
+        Ok(config)
     }
 }
 
@@ -137,6 +166,10 @@ impl Default for Config {
                 model_path: default_model_path(),
                 dimension: default_embedding_dim(),
             },
+            query: QueryConfig {
+                vector_weight: default_vector_weight(),
+                text_weight: default_text_weight(),
+            },
             auth: AuthConfig {
                 enabled: default_auth_enabled(),
                 api_keys: Vec::new(),