fix(webview): harden postMessageToWebview with try/catch; replace magic 10ms with INCREMENTAL_SEND_DELAY_MS; guard Task message send calls with non-fatal errors

Author: hannesrudolph

src/core/task/Task.ts

@@ -545,7 +545,13 @@ export class Task extends EventEmitter<TaskEvents> {
 		this.clineMessages.push(message)
 		const provider = this.providerRef.deref()
 		// Send only the new message instead of the entire state
-		await provider?.postMessageToWebview({ type: "messageCreated", clineMessage: message })
+		if (provider) {
+			try {
+				await provider.postMessageToWebview({ type: "messageCreated", clineMessage: message })
+			} catch (error) {
+				// provider.postMessageToWebview already logs; leave as non-fatal
+			}
+		}
 		this.emit("message", { action: "created", message })
 		await this.saveClineMessages()
 
@@ -567,7 +573,13 @@ export class Task extends EventEmitter<TaskEvents> {
 
 	private async updateClineMessage(message: ClineMessage) {
 		const provider = this.providerRef.deref()
-		await provider?.postMessageToWebview({ type: "messageUpdated", clineMessage: message })
+		if (provider) {
+			try {
+				await provider.postMessageToWebview({ type: "messageUpdated", clineMessage: message })
+			} catch (error) {
+				// provider.postMessageToWebview already logs; leave as non-fatal
+			}
+		}
 		this.emit("message", { action: "updated", message })
 
 		const shouldCaptureMessage = message.partial !== true && CloudService.isEnabled()
@@ -1449,10 +1461,14 @@ export class Task extends EventEmitter<TaskEvents> {
 		await this.saveClineMessages()
 		// Send only the updated API request message instead of the entire state
 		if (provider && lastApiReqIndex >= 0) {
-			await provider.postMessageToWebview({
-				type: "messageUpdated",
-				clineMessage: this.clineMessages[lastApiReqIndex],
-			})
+			try {
+				await provider.postMessageToWebview({
+					type: "messageUpdated",
+					clineMessage: this.clineMessages[lastApiReqIndex],
+				})
+			} catch {
+				// non-fatal
+			}
 		}
 
 		try {
@@ -1716,10 +1732,14 @@ export class Task extends EventEmitter<TaskEvents> {
 			await this.saveClineMessages()
 			// Send only the updated API request message instead of the entire state
 			if (provider && lastApiReqIndex >= 0) {
-				await provider.postMessageToWebview({
-					type: "messageUpdated",
-					clineMessage: this.clineMessages[lastApiReqIndex],
-				})
+				try {
+					await provider.postMessageToWebview({
+						type: "messageUpdated",
+						clineMessage: this.clineMessages[lastApiReqIndex],
+					})
+				} catch {
+					// non-fatal
+				}
 			}
 
 			// Now add to apiConversationHistory.

src/core/webview/ClineProvider.ts

@@ -9,6 +9,9 @@ import axios from "axios"
 import pWaitFor from "p-wait-for"
 import * as vscode from "vscode"
 
+// Small delay used for incremental message delivery to the webview
+const INCREMENTAL_SEND_DELAY_MS = 10
+
 import {
 	type GlobalState,
 	type ProviderName,
@@ -669,7 +672,15 @@ export class ClineProvider
 	}
 
 	public async postMessageToWebview(message: ExtensionMessage) {
-		await this.view?.webview.postMessage(message)
+		try {
+			await this.view?.webview.postMessage(message)
+		} catch (error) {
+			// Guard against unhandled promise rejections from webview messaging
+			const errMsg =
+				error instanceof Error ? error.message : typeof error === "string" ? error : JSON.stringify(error)
+			this.log(`[postMessageToWebview] failed to post message '${message.type}': ${errMsg}`)
+			// Non-fatal: continue without throwing to avoid crashing extension host
+		}
 	}
 
 	private async getHMRHtmlContent(webview: vscode.Webview): Promise<string> {
@@ -1346,7 +1357,7 @@ export class ClineProvider
 			for (const message of currentCline.clineMessages) {
 				await this.postMessageToWebview({ type: "messageCreated", clineMessage: message })
 				// Small delay to prevent overwhelming the webview
-				await delay(10)
+				await delay(INCREMENTAL_SEND_DELAY_MS)
 			}
 		} else {
 			// Normal state update for new tasks or tasks without messages