refactor(mobile): share session presentation semantics

apps/mobile/src/features/chat/components/AgentMessage.tsx

@@ -1,10 +1,10 @@
+import { pickThinkingActivity } from "@posthog/core/sessions/thinkingActivities";
 import { Brain } from "phosphor-react-native";
 import { useState } from "react";
 import { Pressable, Text, View } from "react-native";
 import { formatRelativeTime } from "@/lib/format";
 import { useThemeColors } from "@/lib/theme";
 import { usePeriodicRerender } from "../hooks/usePeriodicRerender";
-import { getRandomThinkingMessage } from "../utils/thinkingMessages";
 import { CopyButton } from "./CopyButton";
 import { MarkdownText } from "./MarkdownText";
 import { ToolMessage } from "./ToolMessage";
@@ -110,7 +110,7 @@ export function AgentMessage({
       {isLoading && !content && !thinkingText && (
         <View className="max-w-[95%] px-4 py-1">
           <Text className="font-mono text-[13px] text-gray-9 italic">
-            {getRandomThinkingMessage()}
+            {pickThinkingActivity(Math.random())}...
           </Text>
         </View>
       )}

apps/mobile/src/features/chat/components/ToolMessage.tsx

@@ -1,3 +1,8 @@
+import {
+  formatPosthogExecBody,
+  getPostHogExecDisplay,
+  isPostHogExecTool,
+} from "@posthog/core/sessions/posthogExecDisplay";
 import { useRouter } from "expo-router";
 import {
   ArrowsClockwise,
@@ -22,11 +27,6 @@ import {
   TouchableOpacity,
   View,
 } from "react-native";
-import {
-  formatPosthogExecBody,
-  getPostHogExecDisplay,
-  isPostHogExecTool,
-} from "@/features/chat/utils/posthogExecDisplay";
 import { McpAppHost } from "@/features/mcp/components/McpAppHost";
 import { isMcpToolName } from "@/features/mcp/utils/mcpToolName";
 import {

apps/mobile/src/features/chat/utils/posthogExecDisplay.test.ts

@@ -1,9 +1,9 @@
-import { describe, expect, it } from "vitest";
 import {
   formatPosthogExecBody,
   getPostHogExecDisplay,
   isPostHogExecTool,
-} from "./posthogExecDisplay";
+} from "@posthog/core/sessions/posthogExecDisplay";
+import { describe, expect, it } from "vitest";
 
 describe("isPostHogExecTool", () => {
   it("matches the bare posthog exec tool", () => {

apps/mobile/src/features/tasks/components/TaskSessionView.test.tsx

@@ -24,8 +24,8 @@ vi.mock("@/features/chat", () => ({
   deriveToolKind: () => "other",
 }));
 
-vi.mock("@/features/chat/utils/thinkingMessages", () => ({
-  getRandomThinkingActivity: () => "Thinking",
+vi.mock("@posthog/core/sessions/thinkingActivities", () => ({
+  pickThinkingActivity: () => "Thinking",
 }));
 
 vi.mock("@/lib/theme", () => ({

apps/mobile/src/features/tasks/components/TaskSessionView.tsx

@@ -2,6 +2,7 @@ import type {
   PortableSessionEvent as SessionEvent,
   PortableSessionNotification as SessionNotification,
 } from "@posthog/core/sessions/portableSessionEvents";
+import { pickThinkingActivity } from "@posthog/core/sessions/thinkingActivities";
 import {
   ArrowDown,
   Brain,
@@ -24,7 +25,6 @@ import {
   ToolMessage,
   type ToolStatus,
 } from "@/features/chat";
-import { getRandomThinkingActivity } from "@/features/chat/utils/thinkingMessages";
 import { useThemeColors } from "@/lib/theme";
 import type {
   CloudPendingPermissionRequest,
@@ -732,7 +732,9 @@ function useElapsedTimer() {
 
 function ThinkingIndicator() {
   const [dots, setDots] = useState(1);
-  const [activity, setActivity] = useState(getRandomThinkingActivity);
+  const [activity, setActivity] = useState(() =>
+    pickThinkingActivity(Math.random()),
+  );
   const elapsed = useElapsedTimer();
   const themeColors = useThemeColors();
 
@@ -745,7 +747,7 @@ function ThinkingIndicator() {
 
   useEffect(() => {
     const interval = setInterval(() => {
-      setActivity(getRandomThinkingActivity());
+      setActivity(pickThinkingActivity(Math.random()));
     }, 2000);
     return () => clearInterval(interval);
   }, []);

packages/core/src/sessions/posthogExecDisplay.ts

@@ -0,0 +1,85 @@
+import { parseMcpToolName } from "@posthog/shared";
+
+const POSTHOG_SERVER_RE = /^(?:plugin_)?posthog(?:_[^_]+)*$/;
+const POSTHOG_VERB_RE =
+  /^\s*(tools|search|info|schema|call)(?:\s+([\s\S]*))?\s*$/;
+const POSTHOG_CALL_BODY_RE = /^(?:--json\s+)?([a-zA-Z0-9_-]+)\s*([\s\S]*)$/;
+const POSTHOG_TOOL_NAME_RE = /^([a-zA-Z0-9_-]+)\s*([\s\S]*)$/;
+
+export interface PostHogExecDisplay {
+  label: string;
+  input?: string;
+}
+
+export function isPostHogExecTool(toolName: string): boolean {
+  const mcp = parseMcpToolName(toolName);
+  return !!mcp && mcp.tool === "exec" && POSTHOG_SERVER_RE.test(mcp.server);
+}
+
+export function getPostHogExecDisplay(
+  toolInput: unknown,
+): PostHogExecDisplay | null {
+  if (!toolInput || typeof toolInput !== "object") return null;
+  const input = toolInput as { command?: unknown; input?: unknown };
+  if (typeof input.command !== "string") return null;
+  const match = input.command.match(POSTHOG_VERB_RE);
+  if (!match) return null;
+  const verb = match[1] as "tools" | "search" | "info" | "schema" | "call";
+  const rest = (match[2] ?? "").trim();
+  const explicitInput = readExplicitInput(input.input);
+
+  switch (verb) {
+    case "tools":
+      return { label: "List tools", input: undefined };
+    case "search":
+      return {
+        label: "Search tools",
+        input: explicitInput ?? (rest || undefined),
+      };
+    case "info":
+      return { label: rest ? `Read ${rest}` : "Read tool", input: undefined };
+    case "schema": {
+      const schema = rest.match(POSTHOG_TOOL_NAME_RE);
+      if (!schema) return { label: "Inspect schema", input: undefined };
+      const path = explicitInput ?? ((schema[2] ?? "").trim() || undefined);
+      return {
+        label: path
+          ? `Inspect ${schema[1]}.${path}`
+          : `Inspect ${schema[1]} fields`,
+        input: undefined,
+      };
+    }
+    case "call": {
+      const call = rest.match(POSTHOG_CALL_BODY_RE);
+      if (!call) return null;
+      return {
+        label: call[1],
+        input: explicitInput ?? ((call[2] ?? "").trim() || undefined),
+      };
+    }
+  }
+}
+
+function readExplicitInput(value: unknown): string | undefined {
+  if (value === undefined || value === null) return undefined;
+  if (typeof value === "string") return value.trim() || undefined;
+  try {
+    return JSON.stringify(value);
+  } catch {
+    return undefined;
+  }
+}
+
+export function formatPosthogExecBody(
+  input: string | undefined,
+): string | undefined {
+  if (!input) return undefined;
+  try {
+    const parsed = JSON.parse(input);
+    if (parsed && typeof parsed === "object")
+      return JSON.stringify(parsed, null, 2);
+  } catch {
+    return input;
+  }
+  return input;
+}

packages/core/src/sessions/thinkingActivities.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+import {
+  pickNextThinkingActivity,
+  pickThinkingActivity,
+  THINKING_ACTIVITIES,
+} from "./thinkingActivities";
+
+describe("thinking activities", () => {
+  it("selects from a bounded random value", () => {
+    expect(pickThinkingActivity(0)).toBe("Booping");
+    expect(pickThinkingActivity(1)).toBe(THINKING_ACTIVITIES.at(-1));
+  });
+
+  it("always advances when the random pick matches the current activity", () => {
+    expect(pickNextThinkingActivity("Booping", 0)).toBe("Crunching");
+  });
+});

apps/mobile/src/features/chat/utils/thinkingMessages.ts → packages/core/src/sessions/thinkingActivities.ts

@@ -1,7 +1,4 @@
-// Random thinking messages displayed while AI is generating
-// Based on posthog/frontend/src/scenes/max/utils/thinkingMessages.ts
-
-export const THINKING_MESSAGES = [
+export const THINKING_ACTIVITIES = [
   "Booping",
   "Crunching",
   "Digging",
@@ -86,13 +83,21 @@ export const THINKING_MESSAGES = [
   "Puttering",
   "Whiffling",
   "Thinking",
-];
+] as const;
 
-export function getRandomThinkingActivity(): string {
-  const randomIndex = Math.floor(Math.random() * THINKING_MESSAGES.length);
-  return THINKING_MESSAGES[randomIndex];
+export function pickThinkingActivity(randomValue: number): string {
+  const bounded = Math.max(0, Math.min(randomValue, 0.999999999999));
+  return THINKING_ACTIVITIES[Math.floor(bounded * THINKING_ACTIVITIES.length)];
 }
 
-export function getRandomThinkingMessage(): string {
-  return `${getRandomThinkingActivity()}...`;
+export function pickNextThinkingActivity(
+  current: string,
+  randomValue: number,
+): string {
+  const picked = pickThinkingActivity(randomValue);
+  if (picked !== current || THINKING_ACTIVITIES.length <= 1) return picked;
+  const index = THINKING_ACTIVITIES.indexOf(
+    current as (typeof THINKING_ACTIVITIES)[number],
+  );
+  return THINKING_ACTIVITIES[(index + 1) % THINKING_ACTIVITIES.length];
 }

packages/ui/src/features/mcp-apps/components/McpToolView.tsx

@@ -2,7 +2,7 @@ import { Plugs } from "@phosphor-icons/react";
 import {
   getPostHogExecDisplay,
   isPostHogExecTool,
-} from "../../posthog-mcp/utils/posthog-exec-display";
+} from "@posthog/core/sessions/posthogExecDisplay";
 import { useChatThreadChrome } from "../../sessions/components/chat-thread/chatThreadChrome";
 import { ToolRow } from "../../sessions/components/session-update/ToolRow";
 import {

packages/ui/src/features/permissions/McpPermission.tsx

@@ -1,9 +1,9 @@
-import { mcpToolKey, readMcpToolDescriptor } from "@posthog/shared";
 import {
   formatPosthogExecBody,
   getPostHogExecDisplay,
   isPostHogExecTool,
-} from "@posthog/ui/features/posthog-mcp/utils/posthog-exec-display";
+} from "@posthog/core/sessions/posthogExecDisplay";
+import { mcpToolKey, readMcpToolDescriptor } from "@posthog/shared";
 import { formatInput } from "@posthog/ui/features/sessions/components/session-update/toolCallUtils";
 import { ActionSelector } from "@posthog/ui/primitives/ActionSelector";
 import { Box, Code } from "@radix-ui/themes";