fix(mcp): propagate internal serialization errors instead of silently swallowing them to prevent LLM hallucination

server/src/handlers/meta.rs

@@ -98,11 +98,15 @@ impl McpTool for DeleteDecisionHandler {
     }
 
     fn schema(&self) -> Value {
-        crate::mcp::tool_def::<crate::tools::DeleteDecisionTool>("delete_decision", "Delete an architectural decision record")
+        crate::mcp::tool_def::<crate::tools::DeleteDecisionTool>(
+            "delete_decision",
+            "Delete an architectural decision record",
+        )
     }
 
     async fn execute(&self, args: Value, state: Arc<MemoryState>) -> Result<String, String> {
-        let req: crate::tools::DeleteDecisionTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
+        let req: crate::tools::DeleteDecisionTool =
+            serde_json::from_value(args).map_err(|e| e.to_string())?;
         let mut found = false;
         state.adrs.modify(|adrs| {
             if let Some(pos) = adrs.iter().position(|a| a.id == req.id) {
@@ -110,7 +114,7 @@ impl McpTool for DeleteDecisionHandler {
                 found = true;
             }
         });
-        
+
         if found {
             state.rebuild_index().await;
             Ok("Decision deleted successfully".to_string())
@@ -337,7 +341,10 @@ impl McpTool for ResolveTechDebtHandler {
         if found {
             Ok("Tech debt resolved".to_string())
         } else {
-            Err("Tech debt not found. Please verify the tech debt ID using list_tech_debt.".to_string())
+            Err(
+                "Tech debt not found. Please verify the tech debt ID using list_tech_debt."
+                    .to_string(),
+            )
         }
     }
 }
@@ -385,7 +392,10 @@ impl McpTool for OmniSearchHandler {
         let req: OmniSearchTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
         let limit = req.limit.unwrap_or(5);
         let include_body = req.include_body.unwrap_or(false);
-        let matches = match state.get_search_index().search(&req.query, req.namespace.as_deref()) {
+        let matches = match state
+            .get_search_index()
+            .search(&req.query, req.namespace.as_deref())
+        {
             Ok(m) => m,
             Err(e) => {
                 return Err(format!(
@@ -403,7 +413,9 @@ impl McpTool for OmniSearchHandler {
                 if doc_type == "entity"
                     && let Some(e) = full.entities.get(id)
                 {
-                    if count >= limit { continue; }
+                    if count >= limit {
+                        continue;
+                    }
                     count += 1;
                     if !include_body {
                         let mut summary = e.clone();
@@ -792,13 +804,13 @@ mod tests {
             dependencies: vec![],
             acceptance_criteria: vec![],
         };
-        
+
         {
             state.tasks.modify(|t| {
                 t.push(task.clone());
             });
         }
-        
+
         state.rebuild_index().await;
         state.get_search_index().reader.reload().unwrap();
 
@@ -808,21 +820,24 @@ mod tests {
             .await
             .unwrap();
         println!("OMNI RES: {}", omni_res);
-        assert!(omni_res.contains("omni-1"), "omni search should return results containing the task id");
+        assert!(
+            omni_res.contains("omni-1"),
+            "omni search should return results containing the task id"
+        );
     }
 
     #[tokio::test]
     async fn test_omni_search_malformed_query() {
         let dir = tempfile::tempdir().unwrap();
         let state = Arc::new(MemoryState::new(dir.path().to_str().unwrap()));
-        
+
         let omni = OmniSearchHandler;
-        
+
         // Pass a malformed Lucene query (unclosed parenthesis)
         let omni_res = omni
             .execute(json!({"query": "title: (unclosed"}), state.clone())
             .await;
-            
+
         assert!(omni_res.is_err());
         let err_msg = omni_res.unwrap_err();
         assert!(err_msg.contains("malformed Lucene syntax"));