refactor(pkg): move atomic file write to dedicated fileutil package

pkg/agent/memory.go

@@ -13,7 +13,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 // MemoryStore manages persistent memory for the agent.
@@ -62,7 +62,7 @@ func (ms *MemoryStore) ReadLongTerm() string {
 func (ms *MemoryStore) WriteLongTerm(content string) error {
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
 	// Using 0o600 (owner read/write only) for secure default permissions.
-	return utils.WriteFileAtomic(ms.memoryFile, []byte(content), 0o600)
+	return fileutil.WriteFileAtomic(ms.memoryFile, []byte(content), 0o600)
 }
 
 // ReadToday reads today's daily note.
@@ -102,7 +102,7 @@ func (ms *MemoryStore) AppendToday(content string) error {
 	}
 
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	return utils.WriteFileAtomic(todayFile, []byte(newContent), 0o600)
+	return fileutil.WriteFileAtomic(todayFile, []byte(newContent), 0o600)
 }
 
 // GetRecentDailyNotes returns daily notes from the last N days.

pkg/auth/store.go

@@ -6,7 +6,7 @@ import (
 	"path/filepath"
 	"time"
 
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 type AuthCredential struct {
@@ -71,7 +71,7 @@ func SaveStore(store *AuthStore) error {
 	}
 
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	return utils.WriteFileAtomic(path, data, 0o600)
+	return fileutil.WriteFileAtomic(path, data, 0o600)
 }
 
 func GetCredential(provider string) (*AuthCredential, error) {

pkg/config/config.go

@@ -7,7 +7,7 @@ import (
 	"sync/atomic"
 
 	"github.com/caarlos0/env/v11"
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 // rrCounter is a global counter for round-robin load balancing across models.
@@ -527,7 +527,7 @@ func SaveConfig(path string, cfg *Config) error {
 	}
 
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	return utils.WriteFileAtomic(path, data, 0o600)
+	return fileutil.WriteFileAtomic(path, data, 0o600)
 }
 
 func (c *Config) WorkspacePath() string {

pkg/cron/service.go

@@ -11,7 +11,7 @@ import (
 	"time"
 
 	"github.com/adhocore/gronx"
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 type CronSchedule struct {
@@ -336,7 +336,7 @@ func (cs *CronService) saveStoreUnsafe() error {
 	}
 
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	return utils.WriteFileAtomic(cs.storePath, data, 0o600)
+	return fileutil.WriteFileAtomic(cs.storePath, data, 0o600)
 }
 
 func (cs *CronService) AddJob(

pkg/fileutil/file.go

@@ -4,7 +4,8 @@
 //
 // Copyright (c) 2026 PicoClaw contributors
 
-package utils
+// Package fileutil provides file manipulation utilities.
+package fileutil
 
 import (
 	"fmt"

pkg/heartbeat/service.go

@@ -19,7 +19,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/state"
 	"github.com/sipeed/picoclaw/pkg/tools"
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 const (
@@ -276,7 +276,7 @@ This file contains tasks for the heartbeat service to check periodically.
 Add your heartbeat tasks below this line:
 `
 
-	if err := utils.WriteFileAtomic(heartbeatPath, []byte(defaultContent), 0o644); err != nil {
+	if err := fileutil.WriteFileAtomic(heartbeatPath, []byte(defaultContent), 0o644); err != nil {
 		hs.logError("Failed to create default HEARTBEAT.md: %v", err)
 	} else {
 		hs.logInfo("Created default HEARTBEAT.md template")

pkg/skills/installer.go

@@ -10,7 +10,7 @@ import (
 	"path/filepath"
 	"time"
 
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 type SkillInstaller struct {
@@ -68,7 +68,7 @@ func (si *SkillInstaller) InstallFromGitHub(ctx context.Context, repo string) er
 	skillPath := filepath.Join(skillDir, "SKILL.md")
 	
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	if err := utils.WriteFileAtomic(skillPath, body, 0o600); err != nil {
+	if err := fileutil.WriteFileAtomic(skillPath, body, 0o600); err != nil {
 		return fmt.Errorf("failed to write skill file: %w", err)
 	}
 

pkg/state/state.go

@@ -9,7 +9,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 // State represents the persistent state for a workspace.
@@ -139,7 +139,7 @@ func (sm *Manager) saveAtomic() error {
 		return fmt.Errorf("failed to marshal state: %w", err)
 	}
 
-	return utils.WriteFileAtomic(sm.stateFile, data, 0o600)
+	return fileutil.WriteFileAtomic(sm.stateFile, data, 0o600)
 }
 
 // load loads the state from disk.

pkg/tools/filesystem.go

@@ -9,7 +9,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/sipeed/picoclaw/pkg/utils"
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 )
 
 // validatePath ensures the given path is within the workspace if restrict is true.
@@ -280,7 +280,7 @@ func (h *hostFs) ReadDir(path string) ([]os.DirEntry, error) {
 func (h *hostFs) WriteFile(path string, data []byte) error {
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
 	// Using 0o600 (owner read/write only) for secure default permissions.
-	return utils.WriteFileAtomic(path, data, 0o600)
+	return fileutil.WriteFileAtomic(path, data, 0o600)
 }
 
 // sandboxFs is a sandboxed fileSystem that operates within a strictly defined workspace using os.Root.

pkg/tools/skills_install.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/sipeed/picoclaw/pkg/fileutil"
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/skills"
 	"github.com/sipeed/picoclaw/pkg/utils"
@@ -198,5 +199,5 @@ func writeOriginMeta(targetDir, registryName, slug, version string) error {
 	}
 
 	// Use unified atomic write utility with explicit sync for flash storage reliability.
-	return utils.WriteFileAtomic(filepath.Join(targetDir, ".skill-origin.json"), data, 0o600)
+	return fileutil.WriteFileAtomic(filepath.Join(targetDir, ".skill-origin.json"), data, 0o600)
 }