Add internal subagent stream and notify policy

pkg/config/config.go

@@ -73,6 +73,7 @@ type SubagentConfig struct {
 	Transport             string                `json:"transport,omitempty"`
 	NodeID                string                `json:"node_id,omitempty"`
 	ParentAgentID         string                `json:"parent_agent_id,omitempty"`
+	NotifyMainPolicy      string                `json:"notify_main_policy,omitempty"`
 	DisplayName           string                `json:"display_name,omitempty"`
 	Role                  string                `json:"role,omitempty"`
 	Description           string                `json:"description,omitempty"`

pkg/config/validate.go

@@ -309,6 +309,13 @@ func validateSubagents(cfg *Config) []error {
 				errs = append(errs, fmt.Errorf("agents.subagents.%s.transport must be one of: local, node", id))
 			}
 		}
+		if policy := strings.TrimSpace(raw.NotifyMainPolicy); policy != "" {
+			switch policy {
+			case "final_only", "milestone", "on_blocked", "always", "internal_only":
+			default:
+				errs = append(errs, fmt.Errorf("agents.subagents.%s.notify_main_policy must be one of: final_only, milestone, on_blocked, always, internal_only", id))
+			}
+		}
 		if transport == "node" && strings.TrimSpace(raw.NodeID) == "" {
 			errs = append(errs, fmt.Errorf("agents.subagents.%s.node_id is required when transport=node", id))
 		}

pkg/config/validate_test.go

@@ -110,3 +110,21 @@ func TestValidateNodeBackedSubagentAllowsMissingPromptFile(t *testing.T) {
 		t.Fatalf("expected node-backed config to be valid, got %v", errs)
 	}
 }
+
+func TestValidateSubagentsRejectsInvalidNotifyMainPolicy(t *testing.T) {
+	t.Parallel()
+
+	cfg := DefaultConfig()
+	cfg.Agents.Subagents["coder"] = SubagentConfig{
+		Enabled:          true,
+		SystemPromptFile: "agents/coder/AGENT.md",
+		NotifyMainPolicy: "loud",
+		Runtime: SubagentRuntimeConfig{
+			Proxy: "proxy",
+		},
+	}
+
+	if errs := Validate(cfg); len(errs) == 0 {
+		t.Fatalf("expected validation errors")
+	}
+}