重构会话管理功能，由后端 opencode 发放 sessionId，后端做 scope

.opencode/tools/session_search.ts

@@ -1,8 +1,11 @@
 import { tool } from "@opencode-ai/plugin";
+import { ToolSessionContextStore } from "../../src/session/toolContextStore.js";
 
 const internalBaseUrl =
   process.env.TJWATER_AGENT_INTERNAL_BASE_URL ?? "http://127.0.0.1:8787";
 const internalToken = process.env.TJWATER_AGENT_INTERNAL_TOKEN ?? "";
+const toolContextStore = new ToolSessionContextStore();
+const initializePromise = toolContextStore.initialize();
 
 export default tool({
   description:
@@ -22,6 +25,11 @@ export default tool({
       .describe("Optional maximum number of hits to return."),
   },
   async execute(args, context) {
+    await initializePromise;
+    const sessionContext = await toolContextStore.read(context.sessionID);
+    if (!sessionContext) {
+      throw new Error(`session context not found for ${context.sessionID}`);
+    }
     const response = await fetch(`${internalBaseUrl}/internal/tools/session-search`, {
       method: "POST",
       headers: {
@@ -31,7 +39,7 @@ export default tool({
       body: JSON.stringify({
         max_results: args.max_results,
         query: args.query,
-        sessionId: context.sessionID,
+        sessionScopeKey: sessionContext.sessionScopeKey,
       }),
     });
     const text = await response.text();