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fix: prevent MCP server restart when toggling tool permissions #8633

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Merged
merged 3 commits into from
Oct 28, 2025
Merged

fix: prevent MCP server restart when toggling tool permissions #8633

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9db94d3
fix: prevent MCP server restart when toggling tool permissions
heyseth Oct 12, 2025
6587316
fix(mcp): prevent server reconnection when toggling disabled state
heyseth Oct 13, 2025
a2e7959
fix(mcp): prevent race condition in isProgrammaticUpdate flag
heyseth Oct 13, 2025
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29 changes: 27 additions & 2 deletions src/services/mcp/McpHub.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,7 @@ export class McpHub {
isConnecting: boolean = false
private refCount: number = 0 // Reference counter for active clients
private configChangeDebounceTimers: Map<string, NodeJS.Timeout> = new Map()
private isProgrammaticUpdate: boolean = false

constructor(provider: ClineProvider) {
this.providerRef = new WeakRef(provider)
Expand Down Expand Up @@ -278,6 +279,11 @@ export class McpHub {
* Debounced wrapper for handling config file changes
*/
private debounceConfigChange(filePath: string, source: "global" | "project"): void {
// Skip processing if this is a programmatic update to prevent unnecessary server restarts
if (this.isProgrammaticUpdate) {
return
}

const key = `${source}-${filePath}`

// Clear existing timer if any
Expand Down Expand Up @@ -1463,7 +1469,15 @@ export class McpHub {
mcpServers: config.mcpServers,
}

await fs.writeFile(configPath, JSON.stringify(updatedConfig, null, 2))
// Set flag to prevent file watcher from triggering server restart
this.isProgrammaticUpdate = true
try {
await fs.writeFile(configPath, JSON.stringify(updatedConfig, null, 2))
// Delay longer than debounce timer (500ms) to ensure watcher event is processed while flag is set
await delay(600)
} finally {
this.isProgrammaticUpdate = false
}
}

public async updateServerTimeout(
Expand Down Expand Up @@ -1686,7 +1700,15 @@ export class McpHub {
targetList.splice(toolIndex, 1)
}

await fs.writeFile(normalizedPath, JSON.stringify(config, null, 2))
// Set flag to prevent file watcher from triggering server restart
this.isProgrammaticUpdate = true
try {
await fs.writeFile(normalizedPath, JSON.stringify(config, null, 2))
// Delay longer than debounce timer (500ms) to ensure watcher event is processed while flag is set
await delay(600)
} finally {
this.isProgrammaticUpdate = false
}

if (connection) {
connection.server.tools = await this.fetchToolsList(serverName, source)
Expand Down Expand Up @@ -1796,6 +1818,9 @@ export class McpHub {
}
this.configChangeDebounceTimers.clear()

// Reset programmatic update flag
this.isProgrammaticUpdate = false

this.removeAllFileWatchers()
for (const connection of this.connections) {
try {
Expand Down