.agents/skills/lib_py/delegation/registry.py

@@ -323,7 +323,11 @@ def _build_parser() -> argparse.ArgumentParser:
     sub = parser.add_subparsers(dest="command", required=True)
 
     p_reg = sub.add_parser("register", help="create a pending job; prints the job id")
-    p_reg.add_argument("--prompt", required=True)
+    # Issue #36: a long prompt goes by file - one argv string is capped at
+    # MAX_ARG_STRLEN (131,072 bytes on Linux).
+    reg_prompt = p_reg.add_mutually_exclusive_group(required=True)
+    reg_prompt.add_argument("--prompt")
+    reg_prompt.add_argument("--prompt-file", help="read the prompt from this file (utf-8)")
     p_reg.add_argument("--agent", default="claude-code")
     p_reg.add_argument("--agent-session", default="herdr:claude")
     p_reg.add_argument("--role", default="Worker", help="logical role for the delegated agent (e.g. Worker, Planner, Reviewer)")
@@ -365,7 +369,9 @@ def _build_parser() -> argparse.ArgumentParser:
     p_update.add_argument("--job", required=True)
     p_update.add_argument("--status", default=None)
     p_update.add_argument("--agent-session", default=None)
-    p_update.add_argument("--prompt", default=None)
+    upd_prompt = p_update.add_mutually_exclusive_group()
+    upd_prompt.add_argument("--prompt", default=None)
+    upd_prompt.add_argument("--prompt-file", default=None, help="read the prompt from this file (utf-8)")
     p_update.add_argument("--iteration", type=int, default=None)
     p_update.add_argument("--attempt-id", type=int, default=None)
     p_update.add_argument("--role", default=None)
@@ -473,15 +479,26 @@ def _operator_write(job_id: str, registry_dir: str, **fields) -> int:
     return 4
 
 
+def _prompt_from_args(parser: argparse.ArgumentParser, args: argparse.Namespace) -> Optional[str]:
+    """The prompt text: from --prompt-file (read verbatim) or from --prompt."""
+    if getattr(args, "prompt_file", None) is None:
+        return args.prompt
+    try:
+        return Path(args.prompt_file).read_text(encoding="utf-8")
+    except (OSError, UnicodeDecodeError) as exc:
+        parser.error(f"cannot read --prompt-file {args.prompt_file}: {exc}")
+
+
 def main(argv: Optional[List[str]] = None) -> int:
     mqtt_common.ensure_env_loaded()
     mqtt_common.setup_logging(logging.INFO)
-    args = _build_parser().parse_args(argv)
+    parser = _build_parser()
+    args = parser.parse_args(argv)
     rd = args.registry_dir
 
     if args.command == "register":
         job_id = register_job(
-            prompt=args.prompt,
+            prompt=_prompt_from_args(parser, args),
             agent=args.agent,
             agent_session=args.agent_session,
             role=args.role,
@@ -540,8 +557,9 @@ def main(argv: Optional[List[str]] = None) -> int:
             fields["status"] = args.status
         if args.agent_session is not None:
             fields["agent_session"] = args.agent_session
-        if args.prompt is not None:
-            fields["prompt"] = args.prompt
+        prompt = _prompt_from_args(parser, args)
+        if prompt is not None:
+            fields["prompt"] = prompt
         if args.iteration is not None:
             fields["iteration"] = args.iteration
         if args.attempt_id is not None:

.agents/skills/multi-agent-mux-delegate-job/SKILL.md

@@ -44,6 +44,8 @@ multi-agent-mux-delegate-job submit \
   #   Liveness contract (Issue #18): the agent heartbeats every N s (automatic),
   #   the job is unresponsive after K x N s (--idle-timeout overrides), `started`
   #   must arrive within T s of the injection or the inject fails closed.
+  #   --prompt-file <path> replaces --prompt for long prompts (Issue #36): one
+  #   argv string is capped at 131,072 bytes on Linux. The loop always uses it.
 
 # 1b) Same, for an agent on another host (no herdr pane, no shared disk):
 #     the brief travels over the broker as a signed retained dispatch and a

.agents/skills/multi-agent-mux-delegate-job/multi-agent-mux-delegate-job

@@ -109,13 +109,15 @@ usage() {
   cat <<'EOF'
 multi-agent-mux-delegate-job <command> [options]
 
-  submit  --agent <name> --prompt <text> [--workdir <dir>] [--agent-session <label>]
+  submit  --agent <name> (--prompt <text> | --prompt-file <path>) [--workdir <dir>] [--agent-session <label>]
           [--timeout <sec>] [--idle-timeout <sec>] [--validate <script>]
           [--heartbeat <sec>] [--heartbeat-misses <count>] [--ack-timeout <sec>]
           [--registry-dir <dir>] [--dry-run] [--role <role_name>]
           [--type <direct|loop|discuss>] [--reviewer <reviewer_agent>]
           [--reviewer-session <reviewer_session>] [--max-iterations <count>]
           [--counterpart-role <role_name>] [--strict-role-check]
+          # --prompt-file passes the prompt by file: one argv string is capped
+          # at 131,072 bytes on Linux (Issue #36). The file is read, not kept.
           # --agent-session herdr:<name> injects into a local herdr pane;
           # --agent-session remote:<name> dispatches over the broker (Issue #18).
           # Liveness contract: the agent heartbeats every --heartbeat N s
@@ -131,7 +133,7 @@ EOF
 }
 
 # ---- arg parsing helpers --------------------------------------------------
-AGENT="claude-code"; PROMPT=""; WORKDIR="$(pwd)"; AGENT_SESSION="herdr:claude"
+AGENT="claude-code"; PROMPT=""; PROMPT_FILE=""; WORKDIR="$(pwd)"; AGENT_SESSION="herdr:claude"
 TIMEOUT=3600; IDLE_TIMEOUT=""; VALIDATE=""; DRY_RUN=0
 # Issue #18 liveness contract (N / K / T). An unset --idle-timeout derives K x N.
 HEARTBEAT_SEC="${MAM_HEARTBEAT_SEC:-30}"; HEARTBEAT_MISSES="${MAM_HEARTBEAT_MISSES:-4}"; ACK_TIMEOUT="${MAM_ACK_TIMEOUT_S:-180}"
@@ -148,6 +150,7 @@ parse_opts() {
     case "$1" in
       --agent) AGENT="$2"; shift 2;;
       --prompt) PROMPT="$2"; shift 2;;
+      --prompt-file) PROMPT_FILE="$2"; shift 2;;
       --workdir) WORKDIR="$2"; shift 2;;
       --agent-session) AGENT_SESSION="$2"; shift 2;;
       --timeout) TIMEOUT="$2"; shift 2;;
@@ -183,7 +186,17 @@ _to_lower() {
 
 cmd_submit() {
   parse_opts "$@"
-  [[ -n "$PROMPT" ]] || { echo "submit requires --prompt" >&2; exit 1; }
+  if [[ -n "$PROMPT_FILE" ]]; then
+    [[ -z "$PROMPT" ]] || { echo "submit takes --prompt or --prompt-file, not both" >&2; exit 1; }
+    [[ "$PROMPT_FILE" == /* ]] || PROMPT_FILE="$(pwd)/$PROMPT_FILE"
+    [[ -f "$PROMPT_FILE" && -r "$PROMPT_FILE" ]] || { echo "submit: cannot read --prompt-file $PROMPT_FILE" >&2; exit 1; }
+    PROMPT="$(<"$PROMPT_FILE")"
+  fi
+  [[ -n "$PROMPT" || -n "$PROMPT_FILE" ]] || { echo "submit requires --prompt or --prompt-file" >&2; exit 1; }
+  # Issue #36: the prompt reaches the registry by file when it came by file,
+  # never as one argv string (capped at 131,072 bytes).
+  local reg_prompt=(--prompt "$PROMPT")
+  [[ -n "$PROMPT_FILE" ]] && reg_prompt=(--prompt-file "$PROMPT_FILE")
   PY="$(pick_python)"
   [[ "$PY" == */* && "$PY" != /* ]] && PY="$(pwd)/$PY"
   cd "$WORKDIR"
@@ -192,7 +205,7 @@ cmd_submit() {
 
   # 1) register job (prints the new job id)
   JOB_ID="$("$PY" "$SCRIPT_DIR/scripts/registry.py" --registry-dir "$REGISTRY_DIR" register \
-      --prompt "$PROMPT" --agent "$AGENT" --agent-session "$AGENT_SESSION" --role "$DELEGATE_ROLE" \
+      "${reg_prompt[@]}" --agent "$AGENT" --agent-session "$AGENT_SESSION" --role "$DELEGATE_ROLE" \
       --timeout "$TIMEOUT" --idle-timeout "$IDLE_TIMEOUT" \
       --heartbeat-sec "$HEARTBEAT_SEC" --heartbeat-misses "$HEARTBEAT_MISSES" --ack-timeout "$ACK_TIMEOUT" \
       --transport "$(_is_remote "$AGENT_SESSION" && echo remote || echo herdr)" \
@@ -392,6 +405,8 @@ EOF
 ## 🔎 Task Description
 $current_prompt
 EOF
+      # Issue #36: the registry gets the prompt by file, not as one argv string
+      printf '%s' "$current_prompt" > "$job_dir/prompt.md"
       echo "provisioned iteration brief: $job_dir/brief.md"
 
       attempt=$((attempt + 1))
@@ -432,7 +447,7 @@ EOF
       "$PY" "$SCRIPT_DIR/scripts/registry.py" --registry-dir "$REGISTRY_DIR" update \
           --job "$JOB_ID" \
           --agent-session "$current_session" \
-          --prompt "$current_prompt" \
+          --prompt-file "$job_dir/prompt.md" \
           --iteration "$iteration" \
           --attempt-id "$attempt" \
           --role "$display_role" \