refactor: implemented state machines for retrieval pipeline, improved tracing

composite-retrieval/src/pipeline/config.rs

@@ -0,0 +1,61 @@
+use serde::{Deserialize, Serialize};
+
+/// Tunable parameters that govern each retrieval stage.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RetrievalTuning {
+    pub entity_vector_take: usize,
+    pub chunk_vector_take: usize,
+    pub entity_fts_take: usize,
+    pub chunk_fts_take: usize,
+    pub score_threshold: f32,
+    pub fallback_min_results: usize,
+    pub token_budget_estimate: usize,
+    pub avg_chars_per_token: usize,
+    pub max_chunks_per_entity: usize,
+    pub graph_traversal_seed_limit: usize,
+    pub graph_neighbor_limit: usize,
+    pub graph_score_decay: f32,
+    pub graph_seed_min_score: f32,
+    pub graph_vector_inheritance: f32,
+}
+
+impl Default for RetrievalTuning {
+    fn default() -> Self {
+        Self {
+            entity_vector_take: 15,
+            chunk_vector_take: 20,
+            entity_fts_take: 10,
+            chunk_fts_take: 20,
+            score_threshold: 0.35,
+            fallback_min_results: 10,
+            token_budget_estimate: 2800,
+            avg_chars_per_token: 4,
+            max_chunks_per_entity: 4,
+            graph_traversal_seed_limit: 5,
+            graph_neighbor_limit: 6,
+            graph_score_decay: 0.75,
+            graph_seed_min_score: 0.4,
+            graph_vector_inheritance: 0.6,
+        }
+    }
+}
+
+/// Wrapper containing tuning plus future flags for per-request overrides.
+#[derive(Debug, Clone)]
+pub struct RetrievalConfig {
+    pub tuning: RetrievalTuning,
+}
+
+impl RetrievalConfig {
+    pub fn new(tuning: RetrievalTuning) -> Self {
+        Self { tuning }
+    }
+}
+
+impl Default for RetrievalConfig {
+    fn default() -> Self {
+        Self {
+            tuning: RetrievalTuning::default(),
+        }
+    }
+}