diff --git a/src/claude/sdk/query.ts b/src/claude/sdk/query.ts
index 5ec76736..a22825b6 100644
--- a/src/claude/sdk/query.ts
+++ b/src/claude/sdk/query.ts
@@ -340,7 +340,10 @@ export function query(config: {
 
     // Spawn Claude Code process
     // Use clean env for global claude to avoid local node_modules/.bin taking precedence
-    const spawnEnv = isCommandOnly ? getCleanEnv() : process.env
+    // Always strip CLAUDECODE env var to prevent nested-session detection (Claude Code 2.1+)
+    const baseEnv = isCommandOnly ? getCleanEnv() : { ...process.env }
+    delete baseEnv.CLAUDECODE
+    const spawnEnv = baseEnv
     logDebug(`Spawning Claude Code process: ${spawnCommand} ${spawnArgs.join(' ')} (using ${isCommandOnly ? 'clean' : 'normal'} env)`)
 
     const child = spawn(spawnCommand, spawnArgs, {