Write run outputs and diagnostics

internal/cli/run.go

@@ -7,17 +7,21 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path"
+	"path/filepath"
 	"sort"
 	"strings"
 	"time"
 
 	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
 	"gitea.maximumdirect.net/eric/notarius/internal/core/config"
+	"gitea.maximumdirect.net/eric/notarius/internal/core/diagnostics"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
 )
 
 const defaultConfigPath = "/usr/local/etc/notarius/config.yml"
+const defaultOutputRoot = "./notarius-output"
 
 const usage = `Usage:
   notarius help
@@ -118,7 +122,7 @@ func runPipelineCommand(args []string, stdout, stderr io.Writer, opts Options) i
 		return 2
 	}
 
-	cfg, _, err := loadConfig(*configPath, opts)
+	cfg, loadedConfigPath, err := loadConfig(*configPath, opts)
 	if err != nil {
 		fmt.Fprintf(stderr, "notarius: %v\n", err)
 		return 1
@@ -127,11 +131,30 @@ func runPipelineCommand(args []string, stdout, stderr io.Writer, opts Options) i
 		cfg.Diagnostics.WorkDir = dir
 	}
 
-	catalog, err := effectiveCatalog(opts)
+	startedAt := opts.Now().UTC()
+	runDir, err := diagnostics.NewRunDirectory(cfg.Diagnostics.WorkDir, cfg.Diagnostics.Retention)
 	if err != nil {
 		fmt.Fprintf(stderr, "notarius: %v\n", err)
 		return 1
 	}
+	invocation := diagnostics.InvocationMetadata{
+		Operation:    "run",
+		PipelineID:   pipelineID,
+		InputPath:    strings.TrimSpace(*inputPath),
+		ConfigPath:   loadedConfigPath,
+		ConfigSource: configSource(*configPath),
+		OnlyLanes:    append([]string(nil), only...),
+		RunID:        runDir.RunID(),
+		StartedAt:    startedAt,
+	}
+	if err := runDir.WriteInvocationMetadata(invocation); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics invocation metadata: %w", err))
+	}
+
+	catalog, err := effectiveCatalog(opts)
+	if err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, err)
+	}
 	effective, err := cfg.Resolve(config.ResolveInput{
 		PipelineID:         pipelineID,
 		Only:               only,
@@ -139,33 +162,38 @@ func runPipelineCommand(args []string, stdout, stderr io.Writer, opts Options) i
 		LLMProfileOverride: *llmProfile,
 	})
 	if err != nil {
-		fmt.Fprintf(stderr, "notarius: %v\n", err)
-		return 1
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, err)
+	}
+	invocation.PipelineDigest = effective.ResolvedPipeline.Digest
+	if err := runDir.WriteInvocationMetadata(invocation); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics invocation metadata: %w", err))
+	}
+	if err := runDir.WriteRedactedEffectiveConfig(effective); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics effective config: %w", err))
+	}
+	if err := runDir.WriteResolvedPipeline(effective.ResolvedPipeline); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics resolved pipeline: %w", err))
 	}
 
 	profileIDs := effectiveLLMProfileIDs(effective.ResolvedPipeline)
 	if len(profileIDs) != 1 {
-		fmt.Fprintf(stderr, "notarius: pipeline %q uses %d distinct LLM profiles; current runs require exactly one: %s\n", pipelineID, len(profileIDs), strings.Join(profileIDs, ", "))
-		return 1
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("pipeline %q uses %d distinct LLM profiles; current runs require exactly one: %s", pipelineID, len(profileIDs), strings.Join(profileIDs, ", ")))
 	}
 
 	rawInput, err := os.ReadFile(strings.TrimSpace(*inputPath))
 	if err != nil {
-		fmt.Fprintf(stderr, "notarius: read input %q: %v\n", strings.TrimSpace(*inputPath), err)
-		return 1
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("read input %q: %w", strings.TrimSpace(*inputPath), err))
 	}
 
 	registries, err := effectiveRegistries(opts)
 	if err != nil {
-		fmt.Fprintf(stderr, "notarius: %v\n", err)
-		return 1
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, err)
 	}
 
 	ctx := context.Background()
 	llmClient, llmProfiles, err := opts.LLMClientFactory(ctx, effective.Config, profileIDs[0])
 	if err != nil {
-		fmt.Fprintf(stderr, "notarius: create LLM client for profile %q: %v\n", profileIDs[0], err)
-		return 1
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("create LLM client for profile %q: %w", profileIDs[0], err))
 	}
 
 	output, err := pipeline.New(registries).Run(ctx, pipeline.RunInput{
@@ -173,22 +201,193 @@ func runPipelineCommand(args []string, stdout, stderr io.Writer, opts Options) i
 		Path:        strings.TrimSpace(*inputPath),
 		RawInput:    rawInput,
 		LLMClient:   llmClient,
-		StartedAt:   opts.Now().UTC(),
+		RunID:       runDir.RunID(),
+		StartedAt:   startedAt,
 		LLMProfiles: llmProfiles,
 		Metadata:    runMetadata(*outputDir, *diagnosticsDir),
 	})
 	if err != nil {
-		fmt.Fprintf(stderr, "notarius: run pipeline %q: %v\n", pipelineID, err)
-		return 1
+		if output.Manifest.PipelineID != "" {
+			_ = runDir.WriteRunManifest(output.Manifest)
+		}
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("run pipeline %q: %w", pipelineID, err))
 	}
 
-	fmt.Fprintf(stdout, "pipeline %q complete: approved=%d rejected=%d\n", effective.PipelineID, len(output.Approved), len(output.Rejected))
+	runOutputDir := filepath.Join(outputRoot(*outputDir), runDir.RunID())
+	if err := writeOutputFiles(runOutputDir, output.OutputFiles); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, err)
+	}
+	if err := runDir.WriteRunManifest(output.Manifest); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics run manifest: %w", err))
+	}
+	if err := runDir.WriteWarnings(output.Warnings); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics warnings: %w", err))
+	}
+	if err := runDir.WriteRunReport(runReport{
+		RunID:            runDir.RunID(),
+		PipelineID:       effective.PipelineID,
+		OutputPath:       runOutputDir,
+		DiagnosticsPath:  runDir.Path(),
+		ApprovedCount:    len(output.Approved),
+		RejectedCount:    len(output.Rejected),
+		WarningCount:     len(output.Warnings),
+		ValidationStatus: output.Manifest.ValidationStatus,
+	}); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("write diagnostics run report: %w", err))
+	}
+	if err := runDir.ApplyRetention(diagnostics.RetentionDecisionInput{
+		RetentionMode: cfg.Diagnostics.Retention,
+		RunSucceeded:  true,
+		HasWarnings:   len(output.Warnings) > 0,
+	}); err != nil {
+		return failPipelineCommand(stderr, runDir, cfg.Diagnostics.Retention, fmt.Errorf("apply diagnostics retention: %w", err))
+	}
+
+	fmt.Fprintf(stdout, "pipeline %q complete: approved=%d rejected=%d output=%s\n", effective.PipelineID, len(output.Approved), len(output.Rejected), runOutputDir)
 	if len(output.Warnings) > 0 {
 		fmt.Fprintf(stderr, "notarius: run completed with %d warning(s)\n", len(output.Warnings))
 	}
 	return 0
 }
 
+type runReport struct {
+	RunID            string `json:"run_id"`
+	PipelineID       string `json:"pipeline_id"`
+	OutputPath       string `json:"output_path"`
+	DiagnosticsPath  string `json:"diagnostics_path,omitempty"`
+	ApprovedCount    int    `json:"approved_count"`
+	RejectedCount    int    `json:"rejected_count"`
+	WarningCount     int    `json:"warning_count"`
+	ValidationStatus string `json:"validation_status,omitempty"`
+}
+
+func failPipelineCommand(stderr io.Writer, runDir *diagnostics.RunDirectory, retention diagnostics.RetentionMode, err error) int {
+	fmt.Fprintf(stderr, "notarius: %v\n", err)
+	if runDir != nil {
+		if logErr := runDir.WriteErrorLog(err.Error()); logErr != nil {
+			fmt.Fprintf(stderr, "notarius: write diagnostics error log: %v\n", logErr)
+		}
+		if retentionErr := runDir.ApplyRetention(diagnostics.RetentionDecisionInput{
+			RetentionMode: retention,
+			RunSucceeded:  false,
+		}); retentionErr != nil {
+			fmt.Fprintf(stderr, "notarius: apply diagnostics retention: %v\n", retentionErr)
+		}
+	}
+	return 1
+}
+
+func configSource(configPath string) string {
+	if strings.TrimSpace(configPath) != "" {
+		return "flag"
+	}
+	return "discovered"
+}
+
+func outputRoot(outputDir string) string {
+	if dir := strings.TrimSpace(outputDir); dir != "" {
+		return dir
+	}
+	return defaultOutputRoot
+}
+
+func writeOutputFiles(runOutputDir string, files []contracts.OutputFile) error {
+	type outputTarget struct {
+		path string
+		file contracts.OutputFile
+	}
+	targets := make([]outputTarget, 0, len(files))
+	for _, file := range files {
+		targetPath, err := outputFilePath(runOutputDir, file.Name)
+		if err != nil {
+			return err
+		}
+		targets = append(targets, outputTarget{path: targetPath, file: file})
+	}
+
+	if err := os.MkdirAll(runOutputDir, 0o755); err != nil {
+		return fmt.Errorf("create output directory %q: %w", runOutputDir, err)
+	}
+	for _, target := range targets {
+		if err := os.MkdirAll(filepath.Dir(target.path), 0o755); err != nil {
+			return fmt.Errorf("create output directory %q: %w", filepath.Dir(target.path), err)
+		}
+		if err := writeFileAtomic(target.path, target.file.Bytes, 0o644); err != nil {
+			return fmt.Errorf("write output file %q: %w", target.file.Name, err)
+		}
+	}
+	return nil
+}
+
+func outputFilePath(runOutputDir, logicalName string) (string, error) {
+	name := strings.TrimSpace(logicalName)
+	if name == "" {
+		return "", fmt.Errorf("output file name must not be empty")
+	}
+	if strings.Contains(name, `\`) {
+		return "", fmt.Errorf("output file name %q must use slash-separated relative paths", name)
+	}
+	if path.IsAbs(name) || filepath.IsAbs(name) {
+		return "", fmt.Errorf("output file name %q must be relative", name)
+	}
+	if strings.Contains(name, "..") {
+		return "", fmt.Errorf("output file name %q must not contain ..", name)
+	}
+	cleaned := path.Clean(name)
+	if cleaned == "." || cleaned != name {
+		return "", fmt.Errorf("output file name %q must be clean", name)
+	}
+
+	root, err := filepath.Abs(runOutputDir)
+	if err != nil {
+		return "", fmt.Errorf("resolve output directory %q: %w", runOutputDir, err)
+	}
+	target, err := filepath.Abs(filepath.Join(root, filepath.FromSlash(cleaned)))
+	if err != nil {
+		return "", fmt.Errorf("resolve output file %q: %w", name, err)
+	}
+	rel, err := filepath.Rel(root, target)
+	if err != nil {
+		return "", fmt.Errorf("resolve output file %q: %w", name, err)
+	}
+	if rel == "." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) || rel == ".." {
+		return "", fmt.Errorf("output file name %q resolves outside output directory", name)
+	}
+	return target, nil
+}
+
+func writeFileAtomic(path string, data []byte, perm os.FileMode) error {
+	dir := filepath.Dir(path)
+	temp, err := os.CreateTemp(dir, "."+filepath.Base(path)+".tmp-*")
+	if err != nil {
+		return err
+	}
+	tempPath := temp.Name()
+	removeTemp := true
+	defer func() {
+		if removeTemp {
+			_ = os.Remove(tempPath)
+		}
+	}()
+
+	if _, err := temp.Write(data); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Chmod(perm); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tempPath, path); err != nil {
+		return err
+	}
+	removeTemp = false
+	return nil
+}
+
 func reorderRunArgs(args []string) []string {
 	var flags []string
 	var positionals []string

internal/cli/run_test.go

@@ -13,6 +13,7 @@ import (
 
 	"gitea.maximumdirect.net/eric/notarius/internal/core/artifacts"
 	"gitea.maximumdirect.net/eric/notarius/internal/core/config"
+	"gitea.maximumdirect.net/eric/notarius/internal/core/diagnostics"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
 	"gitea.maximumdirect.net/eric/notarius/internal/modules/chunk/generic"
@@ -546,10 +547,11 @@ func TestRunPipelineRejectsUnknownFlag(t *testing.T) {
 func TestRunPipelineUnknownPipeline(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := writeSeriatimInput(t)
+	diagnosticsDir := t.TempDir()
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "missing", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "missing", "--config", configPath, "--input", inputPath, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
 	})
 
@@ -564,10 +566,11 @@ func TestRunPipelineUnknownPipeline(t *testing.T) {
 func TestRunPipelineUnknownOnlyLane(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := writeSeriatimInput(t)
+	diagnosticsDir := t.TempDir()
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--only", "missing"}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--only", "missing", "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
 	})
 
@@ -582,10 +585,11 @@ func TestRunPipelineUnknownOnlyLane(t *testing.T) {
 func TestRunPipelineInvalidInputPath(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := filepath.Join(t.TempDir(), "missing.json")
+	diagnosticsDir := t.TempDir()
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
 	})
 
@@ -600,11 +604,13 @@ func TestRunPipelineInvalidInputPath(t *testing.T) {
 func TestRunPipelineSuccessUsesProductionRegistriesAndFakeLLM(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := writeSeriatimInput(t)
+	outputDir := t.TempDir()
+	diagnosticsDir := t.TempDir()
 	client := newFakeRunLLMClient(false)
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(client, nil),
 	})
 
@@ -614,7 +620,7 @@ func TestRunPipelineSuccessUsesProductionRegistriesAndFakeLLM(t *testing.T) {
 	if client.calls != 1 {
 		t.Fatalf("LLM calls = %d, want 1", client.calls)
 	}
-	for _, want := range []string{"dnd-session", "approved=1", "rejected=0"} {
+	for _, want := range []string{"dnd-session", "approved=1", "rejected=0", outputDir} {
 		if !strings.Contains(stdout.String(), want) {
 			t.Fatalf("stdout = %q, want substring %q", stdout.String(), want)
 		}
@@ -627,11 +633,13 @@ func TestRunPipelineSuccessUsesProductionRegistriesAndFakeLLM(t *testing.T) {
 func TestRunPipelineOnlySelectsRequestedLane(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAMLForLanes("dnd-session", "spells", "rituals"))
 	inputPath := writeSeriatimInput(t)
+	outputDir := t.TempDir()
+	diagnosticsDir := t.TempDir()
 	client := newFakeRunLLMClient(false)
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--only", "spells"}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--only", "spells", "--output-dir", outputDir, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(client, nil),
 	})
 
@@ -649,10 +657,11 @@ func TestRunPipelineOnlySelectsRequestedLane(t *testing.T) {
 func TestRunPipelineLLMFactoryFailure(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := writeSeriatimInput(t)
+	diagnosticsDir := t.TempDir()
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), errors.New("factory unavailable")),
 	})
 
@@ -667,11 +676,13 @@ func TestRunPipelineLLMFactoryFailure(t *testing.T) {
 func TestRunPipelineValidationRejectionCompletesSuccessfully(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAML("dnd-session", "dnd/spells"))
 	inputPath := writeSeriatimInput(t)
+	outputDir := t.TempDir()
+	diagnosticsDir := t.TempDir()
 	client := newFakeRunLLMClient(true)
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: fakeLLMFactory(client, nil),
 	})
 
@@ -686,12 +697,14 @@ func TestRunPipelineValidationRejectionCompletesSuccessfully(t *testing.T) {
 func TestRunPipelineLLMProfileOverrideSelectsFactoryProfile(t *testing.T) {
 	configPath := writeTestConfig(t, mvpConfigYAMLWithProfiles("dnd-session"))
 	inputPath := writeSeriatimInput(t)
+	outputDir := t.TempDir()
+	diagnosticsDir := t.TempDir()
 	client := newFakeRunLLMClient(false)
 	factory := &recordingLLMFactory{client: client}
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
 
-	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--llm-profile", "runtime"}, &stdout, &stderr, Options{
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--llm-profile", "runtime", "--output-dir", outputDir, "--diagnostics-dir", diagnosticsDir}, &stdout, &stderr, Options{
 		LLMClientFactory: factory.build,
 	})
 
@@ -703,6 +716,190 @@ func TestRunPipelineLLMProfileOverrideSelectsFactoryProfile(t *testing.T) {
 	}
 }
 
+func TestRunPipelineWritesDurableOutputFiles(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "always"))
+	inputPath := writeSeriatimInput(t)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir}, &stdout, &stderr, Options{
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 0 {
+		t.Fatalf("RunWithOptions() code = %d, stderr=%q", code, stderr.String())
+	}
+	runOutputDir := onlyChildDir(t, outputDir)
+	for _, name := range []string{
+		"index.json",
+		"manifest.json",
+		"artifacts/dnd.spell_cast.json",
+		"rejected.json",
+		"warnings.json",
+	} {
+		if _, err := os.Stat(filepath.Join(runOutputDir, filepath.FromSlash(name))); err != nil {
+			t.Fatalf("expected output file %q: %v", name, err)
+		}
+	}
+	if !strings.Contains(stdout.String(), runOutputDir) {
+		t.Fatalf("stdout = %q, want output path %q", stdout.String(), runOutputDir)
+	}
+	assertNoTemporaryFiles(t, runOutputDir)
+}
+
+func TestRunPipelineRejectsUnsafeOutputFileName(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "always"))
+	inputPath := writeSeriatimInput(t)
+	registries := registriesWithOutput(t, unsafeOutputEncoder{})
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir}, &stdout, &stderr, Options{
+		Registries:       registries,
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 1 {
+		t.Fatalf("RunWithOptions() code = %d, want 1", code)
+	}
+	if !strings.Contains(stderr.String(), "output file name") {
+		t.Fatalf("stderr = %q, want unsafe output file error", stderr.String())
+	}
+	runDir := onlyChildDir(t, diagnosticsDir)
+	if got := string(readFile(t, filepath.Join(runDir, diagnostics.ArtifactErrorLog))); !strings.Contains(got, "output file name") {
+		t.Fatalf("error log = %q, want unsafe output file error", got)
+	}
+}
+
+func TestRunPipelineWritesDiagnosticsArtifactsOnSuccess(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "always"))
+	inputPath := writeSeriatimInput(t)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir}, &stdout, &stderr, Options{
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 0 {
+		t.Fatalf("RunWithOptions() code = %d, stderr=%q", code, stderr.String())
+	}
+	runDir := onlyChildDir(t, diagnosticsDir)
+	for _, name := range []string{
+		diagnostics.ArtifactInvocationMetadata,
+		diagnostics.ArtifactEffectiveConfig,
+		diagnostics.ArtifactResolvedPipeline,
+		diagnostics.ArtifactRunManifest,
+		diagnostics.ArtifactRunReport,
+		diagnostics.ArtifactWarnings,
+	} {
+		if _, err := os.Stat(filepath.Join(runDir, name)); err != nil {
+			t.Fatalf("expected diagnostics artifact %q: %v", name, err)
+		}
+	}
+	report := string(readFile(t, filepath.Join(runDir, diagnostics.ArtifactRunReport)))
+	if !strings.Contains(report, `"approved_count": 1`) || !strings.Contains(report, `"validation_status": "approved"`) || !strings.Contains(report, outputDir) {
+		t.Fatalf("unexpected run report: %s", report)
+	}
+}
+
+func TestRunPipelineWritesErrorLogAfterDiagnosticsCreation(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "always"))
+	inputPath := writeSeriatimInput(t)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath}, &stdout, &stderr, Options{
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), errors.New("factory unavailable")),
+	})
+
+	if code != 1 {
+		t.Fatalf("RunWithOptions() code = %d, want 1", code)
+	}
+	runDir := onlyChildDir(t, diagnosticsDir)
+	if got := string(readFile(t, filepath.Join(runDir, diagnostics.ArtifactErrorLog))); !strings.Contains(got, "factory unavailable") {
+		t.Fatalf("error log = %q, want factory error", got)
+	}
+}
+
+func TestRunPipelineRetentionNeverRemovesSuccessfulWarningFreeDiagnostics(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "never"))
+	inputPath := writeSeriatimInput(t)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir}, &stdout, &stderr, Options{
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 0 {
+		t.Fatalf("RunWithOptions() code = %d, stderr=%q", code, stderr.String())
+	}
+	if entries := childDirs(t, diagnosticsDir); len(entries) != 0 {
+		t.Fatalf("diagnostics run dirs = %v, want none", entries)
+	}
+}
+
+func TestRunPipelineWarningsAreDiagnosedAndReported(t *testing.T) {
+	diagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", diagnosticsDir, "auto"))
+	inputPath := writeSeriatimInput(t)
+	registries := registriesWithOutput(t, warningOutputEncoder{})
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir}, &stdout, &stderr, Options{
+		Registries:       registries,
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 0 {
+		t.Fatalf("RunWithOptions() code = %d, stderr=%q", code, stderr.String())
+	}
+	if !strings.Contains(stderr.String(), "1 warning") {
+		t.Fatalf("stderr = %q, want warning count", stderr.String())
+	}
+	runDir := onlyChildDir(t, diagnosticsDir)
+	warnings := string(readFile(t, filepath.Join(runDir, diagnostics.ArtifactWarnings)))
+	if !strings.Contains(warnings, "synthetic_warning") {
+		t.Fatalf("warnings artifact = %q, want synthetic warning", warnings)
+	}
+}
+
+func TestRunPipelineDiagnosticsDirFlagOverridesConfig(t *testing.T) {
+	configDiagnosticsDir := t.TempDir()
+	overrideDiagnosticsDir := t.TempDir()
+	outputDir := t.TempDir()
+	configPath := writeTestConfig(t, mvpConfigYAMLWithDiagnostics("dnd-session", configDiagnosticsDir, "always"))
+	inputPath := writeSeriatimInput(t)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	code := RunWithOptions([]string{"run", "dnd-session", "--config", configPath, "--input", inputPath, "--output-dir", outputDir, "--diagnostics-dir", overrideDiagnosticsDir}, &stdout, &stderr, Options{
+		LLMClientFactory: fakeLLMFactory(newFakeRunLLMClient(false), nil),
+	})
+
+	if code != 0 {
+		t.Fatalf("RunWithOptions() code = %d, stderr=%q", code, stderr.String())
+	}
+	if entries := childDirs(t, configDiagnosticsDir); len(entries) != 0 {
+		t.Fatalf("config diagnostics dir entries = %v, want none", entries)
+	}
+	if entries := childDirs(t, overrideDiagnosticsDir); len(entries) != 1 {
+		t.Fatalf("override diagnostics dir entries = %v, want one run dir", entries)
+	}
+}
+
 func writeTestConfig(t *testing.T, content string) string {
 	t.Helper()
 	return writeFile(t, "config.yml", content)
@@ -778,6 +975,20 @@ pipelines:
 `
 }
 
+func mvpConfigYAMLWithDiagnostics(pipelineID, diagnosticsDir, retention string) string {
+	return `version: 1
+diagnostics:
+  work_dir: ` + diagnosticsDir + `
+  retention: ` + retention + `
+pipelines:
+  ` + pipelineID + `:
+    input: seriatim
+    artifacts:
+      spells:
+        extract: dnd/spells
+`
+}
+
 func writeSeriatimInput(t *testing.T) string {
 	t.Helper()
 	return writeFile(t, "source.json", `{
@@ -857,6 +1068,110 @@ func (factory *recordingLLMFactory) build(ctx context.Context, cfg config.Config
 	return factory.client, []artifacts.LLMProfileManifest{{ID: strings.TrimSpace(profileID)}}, nil
 }
 
+type unsafeOutputEncoder struct{}
+
+func (unsafeOutputEncoder) Key() string {
+	return "json"
+}
+
+func (unsafeOutputEncoder) Encode(ctx context.Context, req contracts.OutputRequest) (contracts.OutputResult, error) {
+	return contracts.OutputResult{
+		Files: []contracts.OutputFile{
+			{
+				Name:        "../escape.json",
+				ContentType: "application/json",
+				Bytes:       []byte("{}\n"),
+			},
+		},
+	}, nil
+}
+
+type warningOutputEncoder struct{}
+
+func (warningOutputEncoder) Key() string {
+	return "json"
+}
+
+func (warningOutputEncoder) Encode(ctx context.Context, req contracts.OutputRequest) (contracts.OutputResult, error) {
+	result, err := jsonoutput.New().Encode(ctx, req)
+	if err != nil {
+		return contracts.OutputResult{}, err
+	}
+	result.Warnings = append(result.Warnings, contracts.Warning{
+		Scope:      "output",
+		ReasonCode: "synthetic_warning",
+		Message:    "synthetic output warning",
+	})
+	return result, nil
+}
+
+func registriesWithOutput(t *testing.T, encoder contracts.OutputEncoder) pipeline.Registries {
+	t.Helper()
+	registries, err := productionRegistries()
+	if err != nil {
+		t.Fatalf("productionRegistries: %v", err)
+	}
+	outputs := pipeline.NewOutputEncoderRegistry()
+	if err := outputs.RegisterWithSpec(jsonoutput.ModuleSpec(), func() (contracts.OutputEncoder, error) {
+		return encoder, nil
+	}); err != nil {
+		t.Fatalf("register test output encoder: %v", err)
+	}
+	registries.Outputs = outputs
+	return registries
+}
+
+func onlyChildDir(t *testing.T, root string) string {
+	t.Helper()
+	children := childDirs(t, root)
+	if len(children) != 1 {
+		t.Fatalf("child dirs under %q = %v, want one", root, children)
+	}
+	return children[0]
+}
+
+func childDirs(t *testing.T, root string) []string {
+	t.Helper()
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		t.Fatalf("read dir %q: %v", root, err)
+	}
+	var dirs []string
+	for _, entry := range entries {
+		if entry.IsDir() {
+			dirs = append(dirs, filepath.Join(root, entry.Name()))
+		}
+	}
+	return dirs
+}
+
+func readFile(t *testing.T, path string) []byte {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read %q: %v", path, err)
+	}
+	return data
+}
+
+func assertNoTemporaryFiles(t *testing.T, root string) {
+	t.Helper()
+	if err := filepath.WalkDir(root, func(path string, entry os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if strings.Contains(entry.Name(), ".tmp-") {
+			t.Fatalf("temporary file remains after success: %s", path)
+		}
+		return nil
+	}); err != nil {
+		t.Fatalf("walk output dir %q: %v", root, err)
+	}
+}
+
 func fakeCatalog(t *testing.T) pipeline.ModuleCatalog {
 	t.Helper()
 	inputs := pipeline.NewInputAdapterRegistry()

internal/core/diagnostics/run_dir.go

@@ -173,7 +173,7 @@ func (r *RunDirectory) WriteErrorLog(errorMessage string) error {
 	if err != nil {
 		return err
 	}
-	if err := os.WriteFile(path, []byte(errorMessage+"\n"), 0o644); err != nil {
+	if err := writeFileAtomic(path, []byte(errorMessage+"\n"), 0o644); err != nil {
 		return fmt.Errorf("write diagnostics artifact %q: %w", ArtifactErrorLog, err)
 	}
 	return nil
@@ -193,7 +193,7 @@ func (r *RunDirectory) WriteJSONArtifact(name string, payload any) error {
 		return fmt.Errorf("marshal diagnostics artifact %q: %w", name, err)
 	}
 	data = append(data, '\n')
-	if err := os.WriteFile(path, data, 0o644); err != nil {
+	if err := writeFileAtomic(path, data, 0o644); err != nil {
 		return fmt.Errorf("write diagnostics artifact %q: %w", name, err)
 	}
 	return nil
@@ -241,3 +241,39 @@ func (r *RunDirectory) artifactPath(name string) (string, error) {
 	}
 	return artifactPath, nil
 }
+
+func writeFileAtomic(path string, data []byte, perm os.FileMode) error {
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return err
+	}
+
+	temp, err := os.CreateTemp(dir, "."+filepath.Base(path)+".tmp-*")
+	if err != nil {
+		return err
+	}
+	tempPath := temp.Name()
+	removeTemp := true
+	defer func() {
+		if removeTemp {
+			_ = os.Remove(tempPath)
+		}
+	}()
+
+	if _, err := temp.Write(data); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Chmod(perm); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tempPath, path); err != nil {
+		return err
+	}
+	removeTemp = false
+	return nil
+}

internal/core/diagnostics/run_dir_test.go

@@ -118,6 +118,24 @@ func TestWriteJSONArtifactWritesIndentedNewlineTerminatedJSON(t *testing.T) {
 	}
 }
 
+func TestWriteJSONArtifactLeavesNoTemporaryFiles(t *testing.T) {
+	runDir := newTestRunDirectory(t)
+
+	if err := runDir.WriteJSONArtifact("artifact.json", map[string]any{"value": "ok"}); err != nil {
+		t.Fatalf("WriteJSONArtifact: %v", err)
+	}
+
+	entries, err := os.ReadDir(runDir.Path())
+	if err != nil {
+		t.Fatalf("read run directory: %v", err)
+	}
+	for _, entry := range entries {
+		if strings.Contains(entry.Name(), ".tmp-") {
+			t.Fatalf("temporary diagnostics file remains after success: %s", entry.Name())
+		}
+	}
+}
+
 func TestWriteInvocationMetadataFillsMissingRunIDAndStartTime(t *testing.T) {
 	runDir := newTestRunDirectory(t)