feat(service-ai): forward latest user message as ToolExecutionContext.userMessageText

Adds an optional, neutral `userMessageText` to ToolExecutionContext (alongside
currentObjectName/currentViewName) and populates it from the most recent user
message in the agent chat route (reusing extractMessageText). Lets a tool
detect explicit intent — e.g. a confirm/approval — without re-deriving it from
the transcript. Cloud's confirm-before-change gate consumes this; the framework
stays neutral (no phrase semantics here).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

packages/services/service-ai/src/routes/agent-routes.ts

@@ -27,6 +27,20 @@ function extractMessageText(content: unknown): string {
   return '';
 }
 
+/** The text of the most recent user message — forwarded to tools as
+ *  ToolExecutionContext.userMessageText so a tool can detect intent (e.g. an
+ *  explicit confirm/approval) without re-deriving it. Neutral context, like
+ *  currentObjectName; consumers own any semantics. */
+function lastUserMessageText(messages: readonly unknown[]): string | undefined {
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const m = messages[i] as { role?: string; content?: unknown } | undefined;
+    if (m?.role !== 'user') continue;
+    const text = extractMessageText(m.content).trim();
+    if (text) return text;
+  }
+  return undefined;
+}
+
 function detectUserLanguage(messages: readonly unknown[]): string | undefined {
   let text = '';
   for (let i = messages.length - 1; i >= 0; i--) {
@@ -310,6 +324,9 @@ export function buildAgentRoutes(
                     typeof chatContext?.objectName === 'string' ? chatContext.objectName : undefined,
                   currentViewName:
                     typeof chatContext?.viewName === 'string' ? chatContext.viewName : undefined,
+                  // Latest user message text → tools can detect intent (e.g. an
+                  // explicit confirm / approval) without re-deriving it.
+                  userMessageText: lastUserMessageText(rawMessages),
                 }
               : undefined,
           };

packages/spec/src/contracts/ai-service.ts

@@ -427,6 +427,12 @@ export interface ToolExecutionContext {
     currentObjectName?: string;
     /** View the user is currently viewing, if known. */
     currentViewName?: string;
+    /**
+     * Text of the latest user message (neutral context, like currentObjectName).
+     * Forwarded so a tool can detect intent — e.g. an explicit confirm/approval —
+     * without re-deriving it from the transcript. Consumers own any semantics.
+     */
+    userMessageText?: string;
     /** Distributed-trace id for cross-service correlation. */
     traceId?: string;
     /**