siyuan-note/siyuan · warning

plugin file watcher is not supported on mobile

Error message

plugin file watcher is not supported on mobile

What it means

errPluginFileWatchUnsupported is returned by addStorageWatch and removeStorageWatch when file-system watching is unavailable — specifically on mobile builds, where the plugin source watcher is compiled out. Callers asking the kernel to watch a plugin storage path for changes get this sentinel error instead of a watcher.

Source

Thrown at kernel/plugin/source_watcher.go:38

	"crypto/sha256"
	"errors"
	"os"
	"path/filepath"
	"runtime"
	"sync"
	"time"

	"github.com/fsnotify/fsnotify"
	"github.com/siyuan-note/logging"
	"github.com/siyuan-note/siyuan/kernel/util"
)

const (
	pluginSourceReloadDelay  = 300 * time.Millisecond
	pluginSourcePollInterval = time.Second
)

var errPluginFileWatchUnsupported = errors.New("plugin file watcher is not supported on mobile")

type pluginSourceWatchMode uint8

const (
	pluginSourceWatchDisabled pluginSourceWatchMode = iota
	pluginSourceWatchEvents
	pluginSourceWatchPolling
)

type pluginSourceWatchEntry struct {
	path       string
	signature  [sha256.Size]byte
	fileState  pluginSourceFileState
	lastError  string
	verified   bool
	generation uint64
	timer      *time.Timer
}

View on GitHub (pinned to 8641553a1f)

Solutions

  1. Guard watch setup with isPluginFileWatchSupported() (or a build/platform check) and skip silently on mobile.
  2. Treat this sentinel error as an expected no-op on mobile: catch it and continue without a watcher.
  3. On desktop, verify the watcher prerequisites (fsnotify support) are met — this error should not occur there.
  4. If hot-reload is required on mobile, use an alternative refresh mechanism (manual reload / kernel push events) instead of fs watching.

Example fix

// before
if err := p.addStorageWatch(path); err != nil {
    return err
}
// after
if err := p.addStorageWatch(path); err != nil {
    if errors.Is(err, errPluginFileWatchUnsupported) {
        return nil // no fs watching on mobile
    }
    return err
}
Defensive patterns

Strategy: fallback

Validate before calling

// Go
if !isPluginFileWatchSupported() {
    // skip watch setup up-front on mobile
}

Try / catch

if err := p.addStorageWatch(path); err != nil && !errors.Is(err, errPluginFileWatchUnsupported) {
    return err
}

Prevention

When it happens

Trigger: Calling KernelPlugin.addStorageWatch(path) or removeStorageWatch(path) on a mobile (Android/iOS/HarmonyOS) build where isPluginFileWatchSupported() returns false; any kernel path that sets up storage watching while running the gomobile-linked kernel.

Common situations: Plugin relies on storage file hot-reload during development but is being tested on the mobile app; shared code path invoked on mobile after being written for desktop; CI running mobile build targets exercising watch setup.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

AI-assisted analysis of siyuan-note/siyuan@8641553a1f (2026-09-11). Data as JSON: /api/errors/c89b37db339a141a. Report an issue: GitHub.