feat(logging): improve file-backed source cleanup and directory recreation logic

- Added `assertFileBodySourceCleaned` helper to streamline cleanup validations in tests.
- Introduced handling to recreate missing directories during file source operations.
- Enhanced tests to verify behavior after manual directory removal, ensuring robustness.
- Fixed edge cases in log file merging when parts are missing.

internal/logging/request_logger.go

@@ -110,6 +110,9 @@ func (s *FileBodySource) CreatePart(prefix string) (*os.File, error) {
 		return nil, fmt.Errorf("file body source has been cleaned")
 	}
 	prefix = sanitizeTempPrefix(prefix)
+	if errMkdir := os.MkdirAll(s.dir, 0755); errMkdir != nil {
+		return nil, errMkdir
+	}
 	file, errCreate := os.CreateTemp(s.dir, prefix+"-*.tmp")
 	if errCreate != nil {
 		return nil, errCreate
@@ -165,16 +168,23 @@ func (s *FileBodySource) WriteTo(w io.Writer) error {
 		return nil
 	}
 	paths := s.Paths()
-	for i, path := range paths {
-		if i > 0 {
-			if _, errWrite := io.WriteString(w, "\n"); errWrite != nil {
-				return errWrite
-			}
-		}
+	wrote := false
+	for _, path := range paths {
 		file, errOpen := os.Open(path)
 		if errOpen != nil {
+			if os.IsNotExist(errOpen) {
+				continue
+			}
 			return errOpen
 		}
+		if wrote {
+			if _, errWrite := io.WriteString(w, "\n"); errWrite != nil {
+				if errClose := file.Close(); errClose != nil {
+					log.WithError(errClose).Warn("failed to close log part file")
+				}
+				return errWrite
+			}
+		}
 		_, errCopy := io.Copy(w, file)
 		if errClose := file.Close(); errClose != nil {
 			log.WithError(errClose).Warn("failed to close log part file")
@@ -185,6 +195,7 @@ func (s *FileBodySource) WriteTo(w io.Writer) error {
 		if errCopy != nil {
 			return errCopy
 		}
+		wrote = true
 	}
 	return nil
 }
@@ -222,7 +233,7 @@ func (s *FileBodySource) Cleanup() error {
 		}
 	}
 	if dir != "" {
-		if errRemove := os.Remove(dir); errRemove != nil && !os.IsNotExist(errRemove) && firstErr == nil {
+		if errRemove := os.RemoveAll(dir); errRemove != nil && firstErr == nil {
 			firstErr = errRemove
 		}
 	}

internal/logging/request_logger_home_test.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -23,6 +24,57 @@ func (c *stubHomeRequestLogClient) RPushRequestLog(_ context.Context, payload []
 	return nil
 }
 
+func assertFileBodySourceCleaned(t *testing.T, partPaths []string) {
+	t.Helper()
+
+	dirs := make(map[string]struct{}, len(partPaths))
+	for _, path := range partPaths {
+		if _, errStat := os.Stat(path); !os.IsNotExist(errStat) {
+			t.Fatalf("expected part %s to be removed, stat err=%v", path, errStat)
+		}
+		dirs[filepath.Dir(path)] = struct{}{}
+	}
+	for dir := range dirs {
+		if _, errStat := os.Stat(dir); !os.IsNotExist(errStat) {
+			t.Fatalf("expected part dir %s to be removed, stat err=%v", dir, errStat)
+		}
+	}
+}
+
+func TestFileBodySource_RecreatesPartDirAfterManualCleanup(t *testing.T) {
+	logsDir := t.TempDir()
+	source, errSource := NewFileBodySourceInDir(logsDir, "websocket-timeline-test")
+	if errSource != nil {
+		t.Fatalf("NewFileBodySourceInDir: %v", errSource)
+	}
+	if errAppend := source.AppendPart([]byte("before manual cleanup")); errAppend != nil {
+		t.Fatalf("AppendPart before cleanup: %v", errAppend)
+	}
+	if errRemove := os.RemoveAll(logsDir); errRemove != nil {
+		t.Fatalf("RemoveAll logs dir: %v", errRemove)
+	}
+	if errAppend := source.AppendPart([]byte("after manual cleanup")); errAppend != nil {
+		t.Fatalf("AppendPart after cleanup: %v", errAppend)
+	}
+
+	raw, errBytes := source.Bytes()
+	if errBytes != nil {
+		t.Fatalf("Bytes after cleanup: %v", errBytes)
+	}
+	if bytes.Contains(raw, []byte("before manual cleanup")) {
+		t.Fatalf("expected manually removed part to be skipped, got %q", string(raw))
+	}
+	if !bytes.Contains(raw, []byte("after manual cleanup")) {
+		t.Fatalf("expected recreated part content, got %q", string(raw))
+	}
+
+	partPaths := source.Paths()
+	if errCleanup := source.Cleanup(); errCleanup != nil {
+		t.Fatalf("Cleanup: %v", errCleanup)
+	}
+	assertFileBodySourceCleaned(t, partPaths)
+}
+
 func TestFileRequestLogger_HomeEnabled_ForwardsWhenRequestLogEnabled(t *testing.T) {
 	original := currentHomeRequestLogClient
 	defer func() {
@@ -143,11 +195,7 @@ func TestFileRequestLogger_LogRequestWithSourcesWritesLocalLogAndCleansParts(t *
 		t.Fatalf("LogRequestWithOptionsAndSources error: %v", errLog)
 	}
 
-	for _, path := range partPaths {
-		if _, errStat := os.Stat(path); !os.IsNotExist(errStat) {
-			t.Fatalf("expected part %s to be removed, stat err=%v", path, errStat)
-		}
-	}
+	assertFileBodySourceCleaned(t, partPaths)
 
 	entries, errRead := os.ReadDir(logsDir)
 	if errRead != nil {
@@ -245,11 +293,7 @@ func TestFileRequestLogger_HomeEnabled_ForwardsSourceLogAndCleansParts(t *testin
 	if !strings.Contains(got.RequestLog, "Event: websocket.request") {
 		t.Fatalf("forwarded request_log missing websocket request: %s", got.RequestLog)
 	}
-	for _, path := range partPaths {
-		if _, errStat := os.Stat(path); !os.IsNotExist(errStat) {
-			t.Fatalf("expected part %s to be removed, stat err=%v", path, errStat)
-		}
-	}
+	assertFileBodySourceCleaned(t, partPaths)
 }
 
 func TestFileRequestLogger_HomeEnabled_ForwardsStreamingRequestID(t *testing.T) {