diff --git a/bundled_execution_contract_test.go b/bundled_execution_contract_test.go
new file mode 100644
index 0000000..4e26910
--- /dev/null
+++ b/bundled_execution_contract_test.go
@@ -0,0 +1,90 @@
+package promptkit_test
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"reflect"
+	"strings"
+	"testing"
+
+	"go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/promptkit"
+)
+
+func bundledPromptConfig(client *http.Client) promptkit.Config {
+	input := configkit.Input{Source: configkit.Mapping("prompt", map[string]any{"prompts": []any{map[string]any{
+		"id": "prompt", "messages": []any{map[string]any{"role": "user", "content": "hello"}}, "output": map[string]any{"format": "text", "validation_mode": "none"},
+	}}})}
+	return promptkit.Config{HTTPClient: client, Sources: promptkit.ConfigurationSources{Main: &input}}
+}
+
+func TestBundledProfilePreparationAndExecution(t *testing.T) {
+	client := &fakeLLMClient{response: &promptkit.GenerateResponse{Content: "ok"}}
+	engine, err := promptkit.NewEngine(bundledPromptConfig(nil), promptkit.WithLLMClient(client))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := engine.PrepareExecution(context.Background(), promptkit.RunRequest{PromptID: "prompt"}); !errors.Is(err, promptkit.ErrProfileRequired) {
+		t.Fatalf("missing profile = %v", err)
+	}
+	temperature := 0.3
+	request := promptkit.RunRequest{PromptID: "prompt", ProfileID: "gpt-luna-latest", Execution: &promptkit.ExecutionTargetOverride{Temperature: &temperature}}
+	prepared, err := engine.PrepareExecution(context.Background(), request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	details := prepared.Details()
+	if details.SelectedProfileID != "gpt-luna-latest" || details.EffectiveModelParams.Model != "~openai/gpt-luna-latest" || details.EffectiveModelParams.BackendID != "openrouter" || details.EffectiveModelParams.Temperature != temperature {
+		t.Fatalf("prepared target = %+v", details.EffectiveModelParams)
+	}
+	if _, err := engine.Run(context.Background(), request); err != nil {
+		t.Fatal(err)
+	}
+	if len(client.requests) != 1 || client.requests[0].Target.Model != "~openai/gpt-luna-latest" || client.requests[0].Target.BackendID != "openrouter" {
+		t.Fatalf("requests = %+v", client.requests)
+	}
+}
+
+func TestBundledProfileHTTPPayloads(t *testing.T) {
+	t.Setenv("OPENROUTER_API_KEY", "synthetic-key")
+	for _, test := range []struct{ id, model, tier string }{
+		{"auto-low", "openrouter/auto", "low"}, {"auto-medium", "openrouter/auto", "medium"}, {"auto-high", "openrouter/auto", "high"}, {"auto-xhigh", "openrouter/auto", "xhigh"}, {"auto-max", "openrouter/auto", "max"},
+		{"auto", "openrouter/auto", ""}, {"free", "openrouter/free", ""}, {"gpt-luna-latest", "~openai/gpt-luna-latest", ""},
+	} {
+		t.Run(test.id, func(t *testing.T) {
+			var body map[string]any
+			transport := roundTripFunc(func(request *http.Request) (*http.Response, error) {
+				if request.Header.Get("Authorization") != "Bearer synthetic-key" {
+					t.Errorf("authorization = %q", request.Header.Get("Authorization"))
+				}
+				if err := json.NewDecoder(request.Body).Decode(&body); err != nil {
+					t.Fatal(err)
+				}
+				return &http.Response{StatusCode: 200, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(`{"choices":[{"message":{"content":"ok"}}]}`))}, nil
+			})
+			engine, err := promptkit.NewEngine(bundledPromptConfig(&http.Client{Transport: transport}))
+			if err != nil {
+				t.Fatal(err)
+			}
+			if _, err := engine.Run(context.Background(), promptkit.RunRequest{PromptID: "prompt", ProfileID: test.id}); err != nil {
+				t.Fatal(err)
+			}
+			if body["model"] != test.model || body["extra_params"] != nil {
+				t.Fatalf("request = %+v", body)
+			}
+			if test.tier == "" {
+				if _, exists := body["plugins"]; exists {
+					t.Fatalf("unexpected plugins = %+v", body)
+				}
+				return
+			}
+			want := []any{map[string]any{"id": "auto-router", "cost_tier": test.tier}}
+			if !reflect.DeepEqual(body["plugins"], want) {
+				t.Fatalf("plugins = %#v, want %#v", body["plugins"], want)
+			}
+		})
+	}
+}
diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index adfe228..435b08c 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -210,6 +210,10 @@ Scope: bundled-profile execution integration with existing runner/client paths.
 Validation: new request cases and existing generation/profile/override tests.
 Offline HTTP assertions prove payload construction, not provider acceptance.
 
+Completion: offline preparation, injected-client execution, and HTTP payload
+tests verify profile selection, overrides, credentials, router plugins, and model
+slugs. Focused execution tests pass on Go 1.27.0.
+
 ## Stage 5: Verify Bundled Smoke-Test Defaults
 
 Scope: facade-level smoke integration with a synthetic HTTP boundary.