diff --git a/.agents/skills/lib.sh b/.agents/skills/lib.sh
index c65686a..90d08ff 100644
--- a/.agents/skills/lib.sh
+++ b/.agents/skills/lib.sh
@@ -3264,26 +3264,27 @@ mam_control_plane_prefix() {
 # fd 7 (`7>&-` on such a child, as pane_lock's fd 9). The wait is bounded by
 # MAM_UPDATE_ADMISSION_WAIT_S (default 120).
 #
-# mam_update_admit [workspace]: rc 0 admitted (fd 7 held, unless the workspace
-# has no .mam), 1 refused (stderr).
+# mam_update_admit [workspace [fd]]: rc 0 admitted (fd 7, or the given one,
+# held unless the workspace has no .mam), 1 refused (stderr). Delegate submit
+# also takes its target's workspace on fd 8.
 mam_update_admit() {
-  local root="${1:-$WORKSPACE_ROOT}"
+  local root="${1:-$WORKSPACE_ROOT}" fd="${2:-7}"
   local lock="$root/.mam/update-admission.lock" marker="$root/.mam/update-in-progress" st
   # No .mam: not an installed workspace, which is all the update runs in (and a
   # checkout running its own scripts gets no .mam from this).
   [ -d "$root/.mam" ] || return 0
-  if ! exec 7>>"$lock"; then
+  if ! eval "exec $fd>>\"\$lock\""; then
     echo "ERROR: cannot open the update admission lock $lock" >&2
     return 1
   fi
-  case "$(PYTHONPATH="$SKILL_DIR:${PYTHONPATH:-}" python3 -m lib_py.pane_lock acquire --fd 7 --shared --wait-env MAM_UPDATE_ADMISSION_WAIT_S)" in
+  case "$(PYTHONPATH="$SKILL_DIR:${PYTHONPATH:-}" python3 -m lib_py.pane_lock acquire --fd "$fd" --shared --wait-env MAM_UPDATE_ADMISSION_WAIT_S)" in
     locked) ;;
     timeout)
-      exec 7>&-
+      mam_update_admit_release "$fd"
       echo "ERROR: an update of $root holds its admission lock (MAM_UPDATE_ADMISSION_WAIT_S passed); try again when it has finished" >&2
       return 1 ;;
     *)
-      exec 7>&-
+      mam_update_admit_release "$fd"
       echo "ERROR: the update admission lock $lock could not be decided (lib_py.pane_lock)" >&2
       return 1 ;;
   esac
@@ -3296,11 +3297,11 @@ mam_update_admit() {
       echo "NOTE: stale update marker $marker (its update is gone); ignored" >&2
       return 0 ;;
   esac
-  exec 7>&-
+  mam_update_admit_release "$fd"
   echo "ERROR: an update of $root is in progress (marker $marker, holder $st); try again when it has finished" >&2
   return 1
 }
 
 mam_update_admit_release() {
-  exec 7>&-
+  eval "exec ${1:-7}>&-"
 }
diff --git a/.agents/skills/lib_py/update.py b/.agents/skills/lib_py/update.py
index b9372e4..9d326c8 100644
--- a/.agents/skills/lib_py/update.py
+++ b/.agents/skills/lib_py/update.py
@@ -16,6 +16,11 @@ this module what needs parsing. Standard library only, Python 3.9.
   python -m lib_py.update monitor --workspace W
       JSON {"pids": [...], "lock": "free"|"held"}: the monitor daemons
       daemon.find_running recognises, and whether .mam/monitor.lock is held.
+  python -m lib_py.update target-workspace --workspace W --agent-session S
+      The installed workspace a delegate target `herdr:<name>` belongs to
+      (decision 8), when it is not W: the nearest directory holding a .mam
+      at or above its row's pane.cwd, else the row's control_plane
+      workspace_root. Nothing for a rowless or non-herdr target.
   python -m lib_py.update backup-registry --workspace W --dest D
       Copies the registry into D under the registry's own write lock
       (agent-sessions.db.lock, as atomic_yaml takes it): the DB through the
@@ -231,6 +236,31 @@ def precheck(workspace: str, state: dict, herdr: str, env: Mapping[str, str]) ->
     return blockers
 
 
+# --------------------------------------------------------------------------- delegate target
+
+def target_workspace(workspace: str, state: dict, agent_session: str) -> str:
+    if not agent_session.startswith("herdr:"):
+        return ""
+    name = agent_session[len("herdr:"):]
+    row = next((s for s in state.get("herdr_sessions") or []
+                if isinstance(s, dict) and s.get("name") == name), None)
+    if row is None:
+        return ""
+    found = ""
+    cwd = (row.get("pane") or {}).get("cwd") or ""
+    d = _real(cwd) if cwd else ""
+    while d and not found:
+        if os.path.isdir(os.path.join(d, ".mam")):
+            found = d
+        elif os.path.dirname(d) == d:
+            break
+        d = os.path.dirname(d)
+    if not found:
+        root = (row.get("control_plane") or {}).get("workspace_root") or ""
+        found = _real(root) if root else ""
+    return "" if found == _real(workspace) else found
+
+
 # --------------------------------------------------------------------------- monitor
 
 def monitor_state(workspace: str) -> dict:
@@ -288,6 +318,9 @@ def main(argv: Optional[List[str]] = None) -> int:
     s.add_argument("--herdr", required=True)
     s = sub.add_parser("monitor")
     s.add_argument("--workspace", required=True)
+    s = sub.add_parser("target-workspace")
+    s.add_argument("--workspace", required=True)
+    s.add_argument("--agent-session", required=True)
     s = sub.add_parser("backup-registry")
     s.add_argument("--workspace", required=True)
     s.add_argument("--dest", required=True)
@@ -303,6 +336,13 @@ def main(argv: Optional[List[str]] = None) -> int:
         for line in lines:
             print(line)
         return 1 if lines else 0
+    if a.cmd == "target-workspace":
+        try:
+            state = _state()
+        except ValueError:
+            state = {}
+        print(target_workspace(ws, state, a.agent_session))
+        return 0
     if a.cmd == "monitor":
         print(json.dumps(monitor_state(ws)))
         return 0
diff --git a/.agents/skills/multi-agent-mux-delegate-job/multi-agent-mux-delegate-job b/.agents/skills/multi-agent-mux-delegate-job/multi-agent-mux-delegate-job
index 6223140..1b1e488 100755
--- a/.agents/skills/multi-agent-mux-delegate-job/multi-agent-mux-delegate-job
+++ b/.agents/skills/multi-agent-mux-delegate-job/multi-agent-mux-delegate-job
@@ -301,10 +301,19 @@ cmd_submit() {
   local reg_dry=()
   if [[ "$DRY_RUN" == "1" ]]; then reg_dry=(--dry-run); fi
 
-  # Issue #72: no job is registered while an update of the target's workspace
-  # runs; held until the record is written (lib.sh mam_update_admit). A
-  # dry-run record is never dispatched and is not counted by the update.
-  if [[ "$DRY_RUN" != "1" ]]; then mam_update_admit "$WORKSPACE_ROOT" || exit 1; fi
+  # Issue #72: no job is registered while an update of this registry's
+  # workspace or of the target's (its row's workspace, lib_py.update
+  # target-workspace) runs; held until the record is written (lib.sh
+  # mam_update_admit). A dry-run record is never dispatched and is not
+  # counted by the update.
+  if [[ "$DRY_RUN" != "1" ]]; then
+    local target_ws
+    target_ws="$(MAM_STATE_JSON="$(load_state_json)" PYTHONPATH="$SKILL_DIR:${PYTHONPATH:-}" "$PY" -m lib_py.update \
+      target-workspace --workspace "$WORKSPACE_ROOT" --agent-session "$AGENT_SESSION")" \
+      || { echo "ERROR: cannot resolve the workspace of $AGENT_SESSION" >&2; exit 1; }
+    mam_update_admit "$WORKSPACE_ROOT" || exit 1
+    if [[ -n "$target_ws" ]]; then mam_update_admit "$target_ws" 8 || exit 1; fi
+  fi
   # 1) register job (prints the new job id)
   JOB_ID="$("$PY" "$SCRIPT_DIR/scripts/registry.py" --registry-dir "$REGISTRY_DIR" register \
       "${reg_prompt[@]}" --agent "$AGENT" --agent-session "$AGENT_SESSION" --role "$DELEGATE_ROLE" \
@@ -314,7 +323,7 @@ cmd_submit() {
       --job-type "$TYPE" --reviewer "$REVIEWER" --reviewer-session "$REVIEWER_SESSION" \
       --max-iterations "$MAX_ITERATIONS" ${reg_parent[@]+"${reg_parent[@]}"} ${reg_dry[@]+"${reg_dry[@]}"})"
   echo "registered job: $JOB_ID"
-  [[ "$DRY_RUN" == "1" ]] || mam_update_admit_release
+  [[ "$DRY_RUN" == "1" ]] || { mam_update_admit_release; mam_update_admit_release 8; }
 
   # 1-1) Provision job directory and write direct brief.md (MAM Job Restructuring)
   local job_dir="$REGISTRY_DIR/$JOB_ID"
diff --git a/tests/test_issue72_admission.py b/tests/test_issue72_admission.py
index 7df3e44..a8a395f 100644
--- a/tests/test_issue72_admission.py
+++ b/tests/test_issue72_admission.py
@@ -12,6 +12,7 @@ import hashlib
 import json
 import os
 import subprocess
+import sys
 from pathlib import Path
 
 import pytest
@@ -26,8 +27,8 @@ ORC_OLD = "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee"
 def marker(mam_sandbox):
     procs = []
 
-    def make(live: bool):
-        p = mam_sandbox / ".mam" / "update-in-progress"
+    def make(live: bool, root: Path = None):
+        p = (root or mam_sandbox) / ".mam" / "update-in-progress"
         if live:
             proc = subprocess.Popen(["sleep", "120"], start_new_session=True)
             procs.append(proc)
@@ -143,6 +144,62 @@ def test_delegate_submit_registers_no_job(mam_sandbox, mock_herdr, marker):
     assert not list(jobs.glob("*.json")) if jobs.exists() else True
 
 
+@pytest.fixture
+def other_ws(tmp_path):
+    """A second installed workspace B, outside the sandbox (A)."""
+    b = Path(os.path.realpath(tmp_path)) / "ws-b"
+    (b / ".mam").mkdir(parents=True)
+    (b / "sub").mkdir()
+    return b
+
+
+def _submit_to(sandbox, session, env=None):
+    return _run(sandbox, ["bash", _script(sandbox, "multi-agent-mux-delegate-job/multi-agent-mux-delegate-job"),
+                          "submit", "--agent", "claude-code", "--agent-session", session, "--prompt", "hi"], env=env)
+
+
+def _no_job(sandbox):
+    jobs = sandbox / ".mam" / "jobs"
+    return not jobs.exists() or not list(jobs.glob("*.json"))
+
+
+@pytest.mark.parametrize("binding", ["pane-cwd", "control-plane"])
+def test_delegate_submit_takes_the_target_workspace_marker(mam_sandbox, mock_herdr, marker, other_ws, binding):
+    """R1: the target row's workspace (the .mam at or above its pane.cwd, else its
+    control_plane.workspace_root) is checked, not only the caller's."""
+    r = _row("tgt")
+    if binding == "pane-cwd":
+        r["pane"]["cwd"] = str(other_ws / "sub")
+    else:
+        r["pane"]["cwd"] = "/nonexistent/tgt"
+        r["control_plane"] = {"workspace_root": str(other_ws)}
+    _seed(mam_sandbox, [r])
+    marker(True, other_ws)
+    res = _submit_to(mam_sandbox, "herdr:tgt")
+    assert res.returncode != 0, res.stdout + res.stderr
+    assert "an update of %s is in progress" % other_ws in res.stderr, res.stdout + res.stderr
+    assert "registered job" not in res.stdout
+    assert _no_job(mam_sandbox)
+
+
+def test_delegate_submit_waits_for_the_target_workspace_admission_lock(mam_sandbox, mock_herdr, other_ws):
+    _seed(mam_sandbox, [dict(_row("tgt"), pane={"cwd": str(other_ws), "cmd": "claude"})])
+    holder = subprocess.Popen([sys.executable, "-c", "import fcntl, sys, time\n"
+                               "f = open(sys.argv[1], 'a'); fcntl.flock(f, fcntl.LOCK_EX)\n"
+                               "print('locked', flush=True); time.sleep(120)",
+                               str(other_ws / ".mam" / "update-admission.lock")],
+                              stdout=subprocess.PIPE, text=True, start_new_session=True)
+    try:
+        assert holder.stdout.readline().strip() == "locked"
+        res = _submit_to(mam_sandbox, "herdr:tgt", env={"MAM_UPDATE_ADMISSION_WAIT_S": "1"})
+    finally:
+        holder.kill()
+        holder.wait()
+    assert res.returncode != 0, res.stdout + res.stderr
+    assert "an update of %s holds its admission lock" % other_ws in res.stderr, res.stdout + res.stderr
+    assert _no_job(mam_sandbox)
+
+
 @pytest.mark.parametrize("purge", [False, True])
 def test_stop_refuses_and_changes_nothing(mam_sandbox, mock_herdr, marker, purge):
     _seed(mam_sandbox, [_row("gated-stop")])