Centralize remaining runtime constants and add precedence/default fallback coverage

internal/usecase/runner_test.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"testing"
 
+	"gitea.maximumdirect.net/eric/scriptorium/internal/defaults"
 	"gitea.maximumdirect.net/eric/scriptorium/internal/domain"
 	"gitea.maximumdirect.net/eric/scriptorium/internal/validate"
 )
@@ -164,6 +165,12 @@ func TestRunnerRunSuccessful(t *testing.T) {
 	if res.EffectiveModelParams.Model != "m" || res.Endpoint != "http://override/v1" {
 		t.Fatalf("unexpected model params: %+v", res.EffectiveModelParams)
 	}
+	if res.Artifact.Name != defaults.OutputArtifactName {
+		t.Fatalf("expected default output artifact name %q, got %q", defaults.OutputArtifactName, res.Artifact.Name)
+	}
+	if res.Artifact.ContentType != defaults.ContentTypeTextMarkdown {
+		t.Fatalf("expected markdown content type %q, got %q", defaults.ContentTypeTextMarkdown, res.Artifact.ContentType)
+	}
 	if res.RawOutput != "# recap" {
 		t.Fatalf("expected raw output, got %q", res.RawOutput)
 	}
@@ -323,6 +330,36 @@ func TestRunnerRunSelectedProfileBeatsBuiltInDefault(t *testing.T) {
 	}
 }
 
+func TestRunnerRunBuiltInDefaultsUsedWhenProfileOmitsOptionalFields(t *testing.T) {
+	promptRepo := &fakePromptRepo{def: promptDef(domain.FormatText, domain.ValidationNone, 0)}
+	execRepo := &fakeExecutionProfileRepo{profiles: map[string]*domain.ExecutionProfile{
+		"exec": {ID: "exec", Endpoint: "http://profile/v1", Model: "profile-model"},
+	}}
+	llmClient := &fakeLLM{resp: &domain.GenerateResponse{Content: "ok"}}
+	runner := NewRunner(promptRepo, execRepo, defaultArtifactReader(), defaultRenderer(), llmClient, nil)
+
+	res, err := runner.Run(context.Background(), domain.RunRequest{
+		PromptID:  "p",
+		ProfileID: "exec",
+		Inputs:    singleInputRef(),
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.EffectiveModelParams.Temperature != defaults.ExecutionDefaultTemperature {
+		t.Fatalf("expected default temperature %v, got %v", defaults.ExecutionDefaultTemperature, res.EffectiveModelParams.Temperature)
+	}
+	if res.EffectiveModelParams.TopP != defaults.ExecutionDefaultTopP {
+		t.Fatalf("expected default top_p %v, got %v", defaults.ExecutionDefaultTopP, res.EffectiveModelParams.TopP)
+	}
+	if res.EffectiveModelParams.MaxTokens != defaults.ExecutionDefaultMaxTokens {
+		t.Fatalf("expected default max_tokens %d, got %d", defaults.ExecutionDefaultMaxTokens, res.EffectiveModelParams.MaxTokens)
+	}
+	if res.EffectiveModelParams.TimeoutSeconds != defaults.ExecutionDefaultTimeoutSeconds {
+		t.Fatalf("expected default timeout_seconds %d, got %d", defaults.ExecutionDefaultTimeoutSeconds, res.EffectiveModelParams.TimeoutSeconds)
+	}
+}
+
 func TestRunnerRunAPIKeyEnvResolvesFromEnvironment(t *testing.T) {
 	t.Setenv("SCRIPTORIUM_TEST_API_KEY", "secret")
 	promptRepo := &fakePromptRepo{def: promptDef(domain.FormatText, domain.ValidationNone, 0)}
@@ -506,6 +543,30 @@ func TestRunnerRunStructuredRepairRemainsBoundedAndUsesEffectiveModelSettings(t
 	}
 }
 
+func TestBuildOutputArtifactDefaults(t *testing.T) {
+	tests := []struct {
+		name        string
+		format      domain.OutputFormat
+		contentType string
+	}{
+		{name: "text", format: domain.FormatText, contentType: defaults.ContentTypeTextPlain},
+		{name: "markdown", format: domain.FormatMarkdown, contentType: defaults.ContentTypeTextMarkdown},
+		{name: "json", format: domain.FormatJSON, contentType: defaults.ContentTypeApplicationJSON},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			art := buildOutputArtifact("body", tc.format)
+			if art.Name != defaults.OutputArtifactName {
+				t.Fatalf("expected artifact name %q, got %q", defaults.OutputArtifactName, art.Name)
+			}
+			if art.ContentType != tc.contentType {
+				t.Fatalf("expected content type %q, got %q", tc.contentType, art.ContentType)
+			}
+		})
+	}
+}
+
 func promptDef(format domain.OutputFormat, mode domain.ValidationMode, attempts int) *domain.PromptDefinition {
 	return &domain.PromptDefinition{
 		ID:             "p",