fix: address review bugs in devin CLI argument handling

- Add -- separator before prompt in print-mode dispatch to prevent
  flag-like prompts (e.g. '--version') from being parsed as backend flags
- Set HEADLESS=true when MODE=print after parse_args, so build_cmd()
  handles it once instead of duplicating --headless in the dispatch
- Declare 'line' as local in builtin_repl for scope hygiene

Co-Authored-By: Thuong Huynh <admin@huynhthuong.online>

Author: devin-ai-integration[bot]

devin

@@ -111,6 +111,9 @@ parse_args() {
 
 parse_args "$@"
 
+# Print mode implies headless
+[ "$MODE" = "print" ] && HEADLESS=true
+
 # ── Resolve backend binary ───────────────────────────────────────────────────
 
 resolve_backend() {
@@ -152,6 +155,7 @@ build_cmd() {
 
 builtin_repl() {
   local initial_prompt="$1"
+  local line
 
   printf '%s %s — interactive REPL\n' "$PROGRAM_NAME" "$VERSION"
   printf 'Type /help for commands, Ctrl-D to exit.\n'
@@ -225,6 +229,6 @@ case "$MODE" in
     ;;
   print)
     # Single-turn: capture output, print to stdout, exit
-    exec "${CMD[@]}" --headless "$PROMPT"
+    exec "${CMD[@]}" -- "$PROMPT"
     ;;
 esac