fix: attach_command from one builder; no kill/start_command; stop closes a row-less session (Issue #71)

- attach_command is `herdr --session <server> agent attach <herdr name>`
  (`default` written too), built by lib_py.agents.sanitize.attach_command;
  create, resume and reconcile all use it. kill_command and start_command
  are no longer written, and status --json drops start_command.
- The two raw kill-session hints (create exit 43, id_order's orphan) print a
  stop-skill command with --herdr-session instead.
- stop_session.sh closes a session that has no registry row, herdr only and
  without --agent, when herdr runs it inside this workspace; another
  workspace's session is refused (exit 5), a missing one is exit 1, one that
  survives kill-session is exit 6. The registry is not changed.
- Docs: only the SKILL.md lines these changes made wrong; the skill block
  pins follow. Tests that asserted the removed fields keep their intent
  (issue50: create's own row; issue21: no control-root path in
  attach_command; tier2: the new form and the absent fields). S11 pins the
  shim to 4243da5, which changed it on purpose.

Refs #71

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_issue23_24_startup_path.py

@@ -299,10 +299,11 @@ def test_s11_this_branch_does_not_change_the_generated_shim(mam_sandbox):
     true at runtime. Issue #45 changed the heredoc on purpose (the bootstrap
     starts the server with restore-on-restart off, and its review R1 passes
     REAL_HERDR to the config check), and so did the real-server leak fix
-    (only a directory that is itself *-shim is skipped), so the base is
-    that commit."""
+    (only a directory that is itself *-shim is skipped). Issue #71 changed it
+    too (one sanitize definition written in with `declare -f`, agent attach
+    resolved, no silent wrong name), so the base is that commit."""
     repo = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-    base = os.environ.get("MAM_BASE_SHA", "525df2b")
+    base = os.environ.get("MAM_BASE_SHA", "4243da5")
     show = subprocess.run(["git", "show", "%s:.agents/skills/lib.sh" % base],
                           capture_output=True, text=True, cwd=repo)
     if show.returncode != 0:
@@ -316,16 +317,21 @@ def test_s11_this_branch_does_not_change_the_generated_shim(mam_sandbox):
 
 
 def _heredoc_body(text):
+    """What lib.sh writes into the shim: the sanitize function it declares in
+    (Issue #71), then the heredoc."""
     lines = text.splitlines(True)
+    fn = [i for i, line in enumerate(lines) if line.startswith("_sanitize_herdr_agent_name() {")]
+    assert len(fn) == 1, "one _sanitize_herdr_agent_name definition in lib.sh"
+    fn_end = next(j for j in range(fn[0], len(lines)) if lines[j].rstrip("\n") == "}")
     start = None
     for i, line in enumerate(lines):
-        if line.strip() == "cat <<'EOF' > \"$tmp_file\"":
+        if line.strip() == "cat <<'EOF'":
             start = i + 1
             break
     assert start is not None, "shim heredoc not found in lib.sh"
     for j in range(start, len(lines)):
         if lines[j].rstrip("\n") == "EOF":
-            return "".join(lines[start:j])
+            return "".join(lines[fn[0]:fn_end + 1] + lines[start:j])
     raise AssertionError("unterminated shim heredoc")
 
 
@@ -1272,7 +1278,9 @@ def test_s9_a_kill_that_left_the_session_alive_is_reported(mam_sandbox):
     "rolled back" anyway, leaving a `running` row against a failed job."""
     res, published, yaml_text = _run_rollback(mam_sandbox, kill_rc=1, still_alive=True)
     assert res.returncode == 43, res.stdout + res.stderr
-    assert "test-sess" in res.stderr and "kill-session" in res.stderr
+    # Issue #71: the clean-up hint is the stop skill, naming the server
+    assert "Clean it up with: bash .agents/skills/multi-agent-mux-stop/scripts/stop_session.sh --session test-sess --herdr-session default" in res.stderr
+    assert "kill-session -t" not in res.stderr
     assert "rollback-failed" in yaml_text, yaml_text
     assert "status: running" in yaml_text, "a session that is still up must not be called gone"
     assert "delegate_job_id: null" in yaml_text, yaml_text