Add render artifact model, config, and Seriatim adapter contracts

internal/adapters/seriatim/fake_test.go

@@ -148,3 +148,58 @@ func TestFakeRunnerNormalizeError(t *testing.T) {
 		t.Fatal("expected error, got nil")
 	}
 }
+
+func TestFakeRunnerRenderCapturesRequestAndReturnsPath(t *testing.T) {
+	fake := &FakeRunner{}
+	dir := t.TempDir()
+	req := RenderRequest{
+		GeneratedConfigPath: filepath.Join(dir, "config", "seriatim.render.yml"),
+		InputTranscriptPath: filepath.Join(dir, "transcripts", "final.trimmed.json"),
+		OutputRenderedPath:  filepath.Join(dir, "transcripts", "final.trimmed.md"),
+		Format:              "markdown",
+		Title:               "Session render",
+		IncludeTimestamps:   true,
+		IncludeSegmentIDs:   false,
+		IncludeMetadata:     true,
+		StdoutLogPath:       filepath.Join(dir, "logs", "seriatim.render.stdout.log"),
+		StderrLogPath:       filepath.Join(dir, "logs", "seriatim.render.stderr.log"),
+	}
+
+	res, err := fake.Render(context.Background(), req)
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	if len(fake.RenderRequests) != 1 || fake.RenderRequests[0].GeneratedConfigPath == "" {
+		t.Fatalf("render requests = %#v, want captured request", fake.RenderRequests)
+	}
+	if res.OutputRenderedPath != req.OutputRenderedPath {
+		t.Fatalf("rendered path = %q, want %q", res.OutputRenderedPath, req.OutputRenderedPath)
+	}
+	if res.Format != req.Format {
+		t.Fatalf("format = %q, want %q", res.Format, req.Format)
+	}
+	if res.Title != req.Title {
+		t.Fatalf("title = %q, want %q", res.Title, req.Title)
+	}
+
+	cfgData, err := os.ReadFile(req.GeneratedConfigPath)
+	if err != nil {
+		t.Fatalf("read generated config: %v", err)
+	}
+	if !strings.Contains(string(cfgData), "command: render") {
+		t.Fatalf("generated config = %q, want render command marker", string(cfgData))
+	}
+	for _, path := range []string{req.StdoutLogPath, req.StderrLogPath, req.OutputRenderedPath} {
+		if _, err := os.Stat(path); err != nil {
+			t.Fatalf("expected file %q to exist: %v", path, err)
+		}
+	}
+}
+
+func TestFakeRunnerRenderError(t *testing.T) {
+	fake := &FakeRunner{RenderErr: errors.New("boom")}
+	_, err := fake.Render(context.Background(), RenderRequest{})
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}