refactor: cleanup shared constants and add async SDK support for isCallerOrchestrator

- Use shared OPENCODE_STORAGE, MESSAGE_STORAGE, PART_STORAGE constants
- Make isCallerOrchestrator async with SDK fallback for beta
- Fix cache implementation using Symbol sentinel
- Update atlas hooks and sisyphus-junior-notepad to use async isCallerOrchestrator

src/shared/opencode-storage-detection.ts

@@ -3,10 +3,11 @@ import { join } from "node:path"
 import { getDataDir } from "./data-path"
 import { isOpenCodeVersionAtLeast, OPENCODE_SQLITE_VERSION } from "./opencode-version"
 
-let cachedResult: boolean | null = null
+const NOT_CACHED = Symbol("NOT_CACHED")
+let cachedResult: boolean | typeof NOT_CACHED = NOT_CACHED
 
 export function isSqliteBackend(): boolean {
-  if (cachedResult !== null) {
+  if (cachedResult !== NOT_CACHED) {
     return cachedResult
   }
   
@@ -19,5 +20,5 @@ export function isSqliteBackend(): boolean {
 }
 
 export function resetSqliteBackendCache(): void {
-  cachedResult = null
+  cachedResult = NOT_CACHED
 }

src/shared/session-utils.ts

@@ -1,12 +1,22 @@
-import * as path from "node:path"
-import * as os from "node:os"
-import { existsSync, readdirSync } from "node:fs"
-import { join } from "node:path"
-import { findNearestMessageWithFields, MESSAGE_STORAGE } from "../features/hook-message-injector"
+import { findNearestMessageWithFields, findNearestMessageWithFieldsFromSDK } from "../features/hook-message-injector"
 import { getMessageDir } from "./opencode-message-dir"
+import { isSqliteBackend } from "./opencode-storage-detection"
+import type { PluginInput } from "@opencode-ai/plugin"
 
-export function isCallerOrchestrator(sessionID?: string): boolean {
+export async function isCallerOrchestrator(sessionID?: string, client?: PluginInput["client"]): Promise<boolean> {
   if (!sessionID) return false
+
+  // Beta mode: use SDK if client provided
+  if (isSqliteBackend() && client) {
+    try {
+      const nearest = await findNearestMessageWithFieldsFromSDK(client, sessionID)
+      return nearest?.agent?.toLowerCase() === "atlas"
+    } catch {
+      return false
+    }
+  }
+
+  // Stable mode: use JSON files
   const messageDir = getMessageDir(sessionID)
   if (!messageDir) return false
   const nearest = findNearestMessageWithFields(messageDir)