feat(web): rename PostHog chat events, add tool_used tracking, and add client-side ask events

Renames server-side chat events to drop the wa_ prefix (since they fire from
multiple sources), adds a new tool_used event for unified tool call tracking
across the ask agent and MCP server, and introduces client-side wa_ask_* events
for accurate web-only usage dashboards.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: msukkari

CLAUDE.md

@@ -57,6 +57,12 @@ if (!value) { return; }
 if (condition) doSomething();
 ```
 
+## PostHog Event Naming
+
+- The `wa_` prefix is reserved for events that can ONLY be fired from the web app (e.g., `wa_login_with_github`, `wa_chat_feedback_submitted`).
+- Events fired from multiple sources (web app, MCP server, API) must NOT use the `wa_` prefix (e.g., `ask_message_sent`, `tool_used`).
+- Multi-source events should include a `source` property to identify the origin (e.g., `'sourcebot-web-client'`, `'sourcebot-mcp-server'`, `'sourcebot-ask-agent'`).
+
 ## Tailwind CSS
 
 Use Tailwind color classes directly instead of CSS variable syntax:

packages/web/src/app/api/(server)/chat/route.ts

@@ -91,12 +91,15 @@ export const POST = apiHandler(async (req: NextRequest) => {
                 return [];
             }))).flat();
 
-            await captureEvent('wa_chat_message_sent', {
+            const source = req.headers.get('X-Sourcebot-Client-Source') ?? undefined;
+
+            await captureEvent('ask_message_sent', {
                 chatId: id,
                 messageCount: messages.length,
                 selectedReposCount: expandedRepos.length,
+                source,
                 ...(env.EXPERIMENT_ASK_GH_ENABLED === 'true' ? { selectedRepos: expandedRepos } : {}),
-            } );
+            });
 
             const stream = await createMessageStream({
                 chatId: id,

packages/web/src/features/chat/actions.ts

@@ -49,9 +49,10 @@ export const createChat = async ({ source }: { source?: string } = {}) => sew(()
             });
         }
 
-        await captureEvent('wa_chat_thread_created', {
+        await captureEvent('ask_thread_created', {
             chatId: chat.id,
             isAnonymous: isGuestUser,
+            source,
         });
 
         return {

packages/web/src/features/chat/agent.ts

@@ -1,7 +1,6 @@
 import { SBChatMessage, SBChatMessageMetadata } from "@/features/chat/types";
 import { getAnswerPartFromAssistantMessage } from "@/features/chat/utils";
 import { getFileSource } from '@/features/git';
-import { captureEvent } from "@/lib/posthog";
 import { isServiceError } from "@/lib/utils";
 import { LanguageModelV3 as AISDKLanguageModelV3 } from "@ai-sdk/provider";
 import { ProviderOptions } from "@ai-sdk/provider-utils";
@@ -210,13 +209,7 @@ const createAgentStream = async ({
         ],
         toolChoice: "auto",
         onStepFinish: ({ toolResults }) => {
-            toolResults.forEach(({ toolName, output, dynamic }) => {
-                captureEvent('wa_chat_tool_used', {
-                    chatId,
-                    toolName,
-                    success: !isServiceError(output),
-                });
-
+            toolResults.forEach(({ output, dynamic }) => {
                 if (dynamic || isServiceError(output)) {
                     return;
                 }

packages/web/src/features/chat/components/chatThread/chatThread.tsx

@@ -126,6 +126,11 @@ export const ChatThread = ({
             .map((part) => part.data);
         setSources((prev) => [...prev, ...sources]);
 
+        captureEvent('wa_ask_message_sent', {
+            chatId,
+            selectedReposCount: selectedSearchScopes.length,
+        });
+
         _sendMessage(message, {
             body: {
                 selectedSearchScopes,

packages/web/src/features/chat/useCreateNewChatThread.ts

@@ -46,6 +46,10 @@ export const useCreateNewChatThread = ({ isAuthenticated = false }: UseCreateNew
             return;
         }
 
+        captureEvent('wa_ask_thread_created', {
+            chatId: response.id,
+        });
+
         setChatState({
             inputMessage,
             selectedSearchScopes,

packages/web/src/features/mcp/askCodebase.ts

@@ -86,9 +86,10 @@ export const askCodebase = (params: AskCodebaseParams): Promise<AskCodebaseResul
                 },
             });
 
-            await captureEvent('wa_chat_thread_created', {
+            await captureEvent('ask_thread_created', {
                 chatId: chat.id,
                 isAnonymous: !user,
+                source,
             });
 
             if (user) {
@@ -137,10 +138,11 @@ export const askCodebase = (params: AskCodebaseParams): Promise<AskCodebaseResul
 
             let finalMessages: SBChatMessage[] = [];
 
-            await captureEvent('wa_chat_message_sent', {
+            await captureEvent('ask_message_sent', {
                 chatId: chat.id,
                 messageCount: 1,
                 selectedReposCount: selectedRepos.length,
+                source,
                 ...(env.EXPERIMENT_ASK_GH_ENABLED === 'true' ? {
                     selectedRepos: selectedRepos.map(r => r.value)
                 } : {}),

packages/web/src/features/mcp/server.ts

@@ -2,6 +2,7 @@ import {
     languageModelInfoSchema,
 } from '@/features/chat/types';
 import { askCodebase } from '@/features/mcp/askCodebase';
+import { captureEvent } from '@/lib/posthog';
 import { isServiceError } from '@/lib/utils';
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { ChatVisibility } from '@sourcebot/db';
@@ -57,6 +58,11 @@ export async function createMcpServer(): Promise<McpServer> {
         },
         async () => {
             const models = await getConfiguredLanguageModelsInfo();
+            captureEvent('tool_used', {
+                toolName: 'list_language_models',
+                source: 'sourcebot-mcp-server',
+                success: true,
+            });
             return { content: [{ type: "text", text: JSON.stringify(models) }] };
         }
     );
@@ -101,11 +107,22 @@ export async function createMcpServer(): Promise<McpServer> {
                 });
 
                 if (isServiceError(result)) {
+                    captureEvent('tool_used', {
+                        toolName: 'ask_codebase',
+                        source: 'sourcebot-mcp-server',
+                        success: false,
+                    });
                     return {
                         content: [{ type: "text", text: `Failed to ask codebase: ${result.message}` }],
                     };
                 }
 
+                captureEvent('tool_used', {
+                    toolName: 'ask_codebase',
+                    source: 'sourcebot-mcp-server',
+                    success: true,
+                });
+
                 const formattedResponse = dedent`
                 ${result.answer}
 

packages/web/src/features/tools/adapters.ts

@@ -1,6 +1,7 @@
 import { tool } from "ai";
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { z } from "zod";
+import { captureEvent } from "@/lib/posthog";
 import { ToolContext, ToolDefinition } from "./types";
 
 export function toVercelAITool<TName extends string, TShape extends z.ZodRawShape, TMetadata>(
@@ -11,7 +12,21 @@ export function toVercelAITool<TName extends string, TShape extends z.ZodRawShap
         description: def.description,
         inputSchema: def.inputSchema,
         title: def.title,
-        execute: (input) => def.execute(input, context),
+        execute: async (input) => {
+            let success = true;
+            try {
+                return await def.execute(input, context);
+            } catch (error) {
+                success = false;
+                throw error;
+            } finally {
+                captureEvent('tool_used', {
+                    toolName: def.name,
+                    source: context.source ?? 'unknown',
+                    success,
+                });
+            }
+        },
         toModelOutput: ({ output }) => ({
             type: "content",
             value: [{ type: "text", text: output.output }],
@@ -41,8 +56,18 @@ export function registerMcpTool<TName extends string, TShape extends z.ZodRawSha
             try {
                 const parsed = def.inputSchema.parse(input);
                 const result = await def.execute(parsed, context);
+                captureEvent('tool_used', {
+                    toolName: def.name,
+                    source: context.source ?? 'unknown',
+                    success: true,
+                });
                 return { content: [{ type: "text" as const, text: result.output }] };
             } catch (error) {
+                captureEvent('tool_used', {
+                    toolName: def.name,
+                    source: context.source ?? 'unknown',
+                    success: false,
+                });
                 const message = error instanceof Error ? error.message : String(error);
                 return { content: [{ type: "text" as const, text: `Tool "${def.name}" failed: ${message}` }], isError: true };
             }

packages/web/src/lib/posthogEvents.ts

@@ -159,24 +159,33 @@ export type PosthogEventMap = {
         chatId: string,
         messageId: string,
     },
-    wa_chat_thread_created: {
+    wa_ask_thread_created: {
+        chatId: string,
+    },
+    wa_ask_message_sent: {
+        chatId: string,
+        selectedReposCount: number,
+    },
+    ask_thread_created: {
         chatId: string,
         isAnonymous: boolean,
+        source?: string,
     },
-    wa_chat_message_sent: {
+    ask_message_sent: {
         chatId: string,
         messageCount: number,
         selectedReposCount: number,
+        source?: string,
         /**
          * @note this field will only be populated when
          * the EXPERIMENT_ASK_GH_ENABLED environment variable
          * is set to true.
          */
         selectedRepos?: string[],
     },
-    wa_chat_tool_used: {
-        chatId: string,
+    tool_used: {
         toolName: string,
+        source: string,
         success: boolean,
     },
     wa_chat_share_dialog_opened: {