refactor: stabilize runtime and unify config

pkg/config/normalized_test.go

@@ -0,0 +1,30 @@
+package config
+
+import "testing"
+
+func TestNormalizedViewProjectsCoreAndRuntime(t *testing.T) {
+	cfg := DefaultConfig()
+	cfg.Agents.Router.Enabled = true
+	cfg.Agents.Subagents["coder"] = SubagentConfig{
+		Enabled:          true,
+		Role:             "coding",
+		SystemPromptFile: "agents/coder/AGENT.md",
+		Tools:            SubagentToolsConfig{Allowlist: []string{"shell"}},
+		Runtime:          SubagentRuntimeConfig{Provider: "openai"},
+	}
+
+	view := cfg.NormalizedView()
+	if view.Core.DefaultProvider != "openai" || view.Core.DefaultModel != "gpt-5.4" {
+		t.Fatalf("unexpected default model projection: %+v", view.Core)
+	}
+	subcfg, ok := view.Core.Subagents["coder"]
+	if !ok {
+		t.Fatalf("expected normalized subagent")
+	}
+	if subcfg.Prompt != "agents/coder/AGENT.md" || subcfg.Provider != "openai" {
+		t.Fatalf("unexpected normalized subagent: %+v", subcfg)
+	}
+	if !view.Runtime.Router.Enabled || view.Runtime.Router.Strategy != "rules_first" {
+		t.Fatalf("unexpected runtime router: %+v", view.Runtime.Router)
+	}
+}