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Handle atomic-save file replacements #8

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Handle atomic-save file replacements #8

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104 changes: 79 additions & 25 deletions src/main/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ interface WindowState {
watcher: FSWatcher | null
isInternalSave: boolean
debounceTimer: ReturnType<typeof setTimeout> | null
rewatchTimer: ReturnType<typeof setTimeout> | null
agentState: 'idle' | 'active' | 'cooldown'
lastExternalChange: number
agentCooldownTimer: ReturnType<typeof setTimeout> | null
Expand All @@ -38,7 +39,7 @@ let pendingFilePaths: string[] = []
function getState(win: BrowserWindow): WindowState {
let state = windowStates.get(win.id)
if (!state) {
state = { filePath: null, watcher: null, isInternalSave: false, debounceTimer: null, agentState: 'idle', lastExternalChange: 0, agentCooldownTimer: null }
state = { filePath: null, watcher: null, isInternalSave: false, debounceTimer: null, rewatchTimer: null, agentState: 'idle', lastExternalChange: 0, agentCooldownTimer: null }
windowStates.set(win.id, state)
}
return state
Expand Down Expand Up @@ -103,11 +104,23 @@ function suggestFileName(win: BrowserWindow, content?: string): string | undefin
return match[1].trim().replace(/[/\\:*?"<>|]/g, '').slice(0, 60) || undefined
}

function stopWatching(state: WindowState): void {
function clearWatchResources(state: WindowState): void {
if (state.watcher) {
state.watcher.close()
state.watcher = null
}
if (state.debounceTimer) {
clearTimeout(state.debounceTimer)
state.debounceTimer = null
}
if (state.rewatchTimer) {
clearTimeout(state.rewatchTimer)
state.rewatchTimer = null
}
}

function stopWatching(state: WindowState): void {
clearWatchResources(state)
if (state.agentCooldownTimer) {
clearTimeout(state.agentCooldownTimer)
state.agentCooldownTimer = null
Expand Down Expand Up @@ -143,32 +156,73 @@ function transitionAgentState(win: BrowserWindow, state: WindowState, newState:
}
}

function watchFile(win: BrowserWindow, state: WindowState): void {
function markExternalChange(win: BrowserWindow, state: WindowState): void {
const now = Date.now()
const gap = now - state.lastExternalChange
state.lastExternalChange = now

if (gap > 0 && gap < 2000) {
transitionAgentState(win, state, 'active')
} else if (state.agentState === 'active') {
transitionAgentState(win, state, 'active')
}
}

function scheduleFileReload(win: BrowserWindow, state: WindowState, filePath: string): void {
if (state.debounceTimer) clearTimeout(state.debounceTimer)
state.debounceTimer = setTimeout(() => {
state.debounceTimer = null
readFile(filePath, 'utf-8')
.then((data) => {
if (!win.isDestroyed()) win.webContents.send('file-changed', data)
})
.catch(() => {})
}, 100)
}

function scheduleRewatch(win: BrowserWindow, state: WindowState, filePath: string, attempt = 0): void {
if (state.filePath !== filePath) return
if (state.watcher) {
state.watcher.close()
state.watcher = null
}
if (state.rewatchTimer) clearTimeout(state.rewatchTimer)

const delay = Math.min(50 * 2 ** attempt, 1000)
state.rewatchTimer = setTimeout(() => {
state.rewatchTimer = null
if (state.filePath === filePath) {
watchFile(win, state, attempt + 1)
}
}, delay)
}

function watchFile(win: BrowserWindow, state: WindowState, attempt = 0): void {
if (!state.filePath) return
stopWatching(state)

const filePath = state.filePath
state.watcher = watch(filePath, (eventType) => {
if (eventType !== 'change' || state.isInternalSave) return

// Agent activity detection
const now = Date.now()
const gap = now - state.lastExternalChange
state.lastExternalChange = now
if (gap > 0 && gap < 2000) {
transitionAgentState(win, state, 'active')
} else if (state.agentState === 'active') {
transitionAgentState(win, state, 'active') // reset cooldown timer
}
clearWatchResources(state)

if (state.debounceTimer) clearTimeout(state.debounceTimer)
state.debounceTimer = setTimeout(() => {
readFile(filePath, 'utf-8')
.then((data) => {
if (!win.isDestroyed()) win.webContents.send('file-changed', data)
})
.catch(() => {})
}, 100)
})
try {
state.watcher = watch(filePath, (eventType) => {
if (state.isInternalSave) return

markExternalChange(win, state)
scheduleFileReload(win, state, filePath)

// Many editors and AI tools save by renaming a temp file into place.
// Re-establish the watcher so live reload keeps working after atomic saves.
if (eventType === 'rename') {
scheduleRewatch(win, state, filePath)
}
})

state.watcher.on('error', () => {
scheduleRewatch(win, state, filePath, attempt)
})
} catch {
scheduleRewatch(win, state, filePath, attempt)
}
}

function loadFileInWindow(win: BrowserWindow, filePath: string): void {
Expand Down