fix: unset CLAUDECODE env var to allow nested Claude Code sessions in spawned coders

This fixes the issue where spawned coder sessions would fail with 'Claude Code cannot be launched inside another Claude Code session' error. The fix unsets the CLAUDECODE environment variable before launching the Claude CLI in tmux sessions.

Author: Jayphen

packages/go/cmd/coders/spawn.go

@@ -327,7 +327,8 @@ func buildToolCommand(tool, task, model, sessionID string, useOllama bool) strin
 	}
 
 	// Set environment variables
-	envVars := fmt.Sprintf("CODERS_SESSION_ID=%s", sessionID)
+	// Unset CLAUDECODE to allow nested Claude Code sessions
+	envVars := fmt.Sprintf("CLAUDECODE= CODERS_SESSION_ID=%s", sessionID)
 
 	// Add Ollama env var mappings if --ollama flag is set
 	if useOllama {