fix(tools): improve error handling and search result formatting

- focus: log warnings on DeleteKV and corrupt knowledge block instead
  of silently swallowing errors
- retrieval: include search method (keyword/semantic) in result messages
  for clearer agent context
- subagent test: respect iterator yield protocol by checking return value

pkg/tools/focus.go

@@ -197,8 +197,9 @@ func (t *CompleteFocusTool) Execute(ctx context.Context, args map[string]interfa
 	pruned := t.pruneHistory(history, state.CheckpointIndex)
 	t.sessions.SetHistory(sk, pruned)
 
-	// Clean up focus state
-	_ = t.delegate.DeleteKV(ctx, focusAgentID, focusKey)
+	if err := t.delegate.DeleteKV(ctx, focusAgentID, focusKey); err != nil {
+		logger.WarnCF("focus", "failed to clean up focus state", map[string]interface{}{"error": err, "session": sk})
+	}
 
 	msgsBefore := len(history)
 	msgsAfter := len(pruned)
@@ -252,7 +253,9 @@ func (t *CompleteFocusTool) appendKnowledge(ctx context.Context, sessionKey, top
 	kb := &KnowledgeBlock{}
 	raw, err := t.delegate.GetKV(ctx, focusAgentID, kvKey)
 	if err == nil && raw != "" {
-		_ = jsonv2.Unmarshal([]byte(raw), kb)
+		if uerr := jsonv2.Unmarshal([]byte(raw), kb); uerr != nil {
+			logger.WarnCF("focus", "corrupt knowledge block, resetting", map[string]interface{}{"error": uerr, "key": kvKey})
+		}
 	}
 
 	kb.Entries = append(kb.Entries, KnowledgeEntry{

pkg/tools/retrieval.go

@@ -66,7 +66,7 @@ func (t *KeywordSearchTool) Execute(ctx context.Context, args map[string]interfa
 		return ErrorResult(fmt.Sprintf("keyword search failed: %v", err))
 	}
 
-	return SilentResult(formatSearchResults("keyword_search", query, results))
+	return SilentResult(formatSearchResults("keyword", query, results))
 }
 
 // SemanticSearchTool performs vector ANN search using embeddings.
@@ -136,7 +136,7 @@ func (t *SemanticSearchTool) Execute(ctx context.Context, args map[string]interf
 		return ErrorResult(fmt.Sprintf("semantic search failed: %v", err))
 	}
 
-	return SilentResult(formatSearchResults("semantic_search", query, results))
+	return SilentResult(formatSearchResults("semantic", query, results))
 }
 
 // ChunkReadTool loads full document/chunk content by ID.
@@ -185,13 +185,13 @@ func (t *ChunkReadTool) Execute(ctx context.Context, args map[string]interface{}
 	return SilentResult(content)
 }
 
-func formatSearchResults(source, query string, results []memory.SearchResult) string {
+func formatSearchResults(method, query string, results []memory.SearchResult) string {
 	if len(results) == 0 {
-		return fmt.Sprintf("No results found for: %s", query)
+		return fmt.Sprintf("No %s results found for: %s", method, query)
 	}
 
 	var sb strings.Builder
-	fmt.Fprintf(&sb, "Found %d results for '%s':\n\n", len(results), query)
+	fmt.Fprintf(&sb, "Found %d %s results for '%s':\n\n", len(results), method, query)
 
 	for i, r := range results {
 		fmt.Fprintf(&sb, "%d. [%s] (score: %.2f) id=%s\n", i+1, r.Source, r.Score, r.ID)

pkg/tools/retrieval_test.go

@@ -55,8 +55,8 @@ func TestChunkReadTool_MissingID(t *testing.T) {
 }
 
 func TestFormatSearchResults_Empty(t *testing.T) {
-	output := formatSearchResults("test", "query", nil)
-	assert.Contains(t, output, "No results found")
+	output := formatSearchResults("keyword", "query", nil)
+	assert.Contains(t, output, "No keyword results found")
 }
 
 func TestFormatSearchResults_WithResults(t *testing.T) {

pkg/tools/subagent_tool_test.go

@@ -39,7 +39,9 @@ func (m *MockLanguageModel) Stream(_ context.Context, call fantasy.Call) (fantas
 		return nil, err
 	}
 	return func(yield func(fantasy.StreamPart) bool) {
-		yield(fantasy.StreamPart{Type: fantasy.StreamPartTypeTextDelta, Delta: resp.Content.Text()})
+		if !yield(fantasy.StreamPart{Type: fantasy.StreamPartTypeTextDelta, Delta: resp.Content.Text()}) {
+			return
+		}
 		yield(fantasy.StreamPart{Type: fantasy.StreamPartTypeFinish, FinishReason: fantasy.FinishReasonStop})
 	}, nil
 }