fix(bot-relay): sweep stale relay artifacts + never leak the deliver tempfile

Widen the DM tempfile-leak fix (#91902/#92407) to the sibling sites
PR #92784 introduced:

- tools/bot_relay.py: expose the 6h stale sweep as
  cleanup_bot_relay_artifacts() (cleanup_*_cache contract) and wire it
  into gateway housekeeping — previously it ran only when the Desktop
  drained the outbox, so plaintext envelopes/replies queued while the
  Desktop was away could sit on disk forever.
- tui_gateway/methods_bot_relay.py: move the payload write inside the
  try/finally so a failed write no longer leaks hermes-relay-dm-*.txt.
- tools/bot_mode_dm.py: _spawn_delivery takes dm_file=None for relay
  waiter deliveries, which have no plaintext DM tempfile to reclaim.

gateway/run.py

@@ -30197,6 +30197,7 @@ def _start_gateway_housekeeping(stop_event: threading.Event, adapters=None, loop
     )
     from tools.tool_result_storage import cleanup_spillover_cache
     from tools.bot_mode_dm import cleanup_bot_dm_cache
+    from tools.bot_relay import cleanup_bot_relay_artifacts
     from hermes_cli.debug import _sweep_expired_pastes
 
     IMAGE_CACHE_EVERY = 60   # ticks — once per hour at default 60s interval
@@ -30217,6 +30218,7 @@ def _start_gateway_housekeeping(stop_event: threading.Event, adapters=None, loop
         ("Screenshot", cleanup_screenshot_cache),
         ("Spillover", cleanup_spillover_cache),
         ("Bot DM", cleanup_bot_dm_cache),
+        ("Bot relay", cleanup_bot_relay_artifacts),
     )
 
     logger.info("Gateway housekeeping started (interval=%ds)", interval)

tests/tools/test_bot_relay.py

@@ -288,3 +288,40 @@ def test_capability_fingerprint_changes_with_relay_roster(tmp_path):
     ])
     after = bot_mode_probe.capability_fingerprint(home)
     assert before != after  # eternal Bot Chats refresh once on roster change
+
+
+# ── stale artifact sweep (housekeeping contract) ─────────────────────────────
+
+
+def test_cleanup_bot_relay_artifacts_sweeps_stale_plaintext(tmp_path, monkeypatch):
+    import os as _os
+    import time as _time
+
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    target = {"profile": "scout", "handle": "scout", "connection_id": "cloud-1",
+              "connection_label": "", "title": "", "description": ""}
+    stale_env = bot_relay.enqueue_envelope(
+        tmp_path, target=target, message="old secret",
+        sender_profile="default", sender_handle="hermes",
+    )
+    fresh_env = bot_relay.enqueue_envelope(
+        tmp_path, target=target, message="new secret",
+        sender_profile="default", sender_handle="hermes",
+    )
+    base = bot_relay.relay_root(tmp_path)
+    stale_reply = bot_relay.write_reply(tmp_path, stale_env["id"], reply="done")
+    old = _time.time() - bot_relay.STALE_AFTER_SECONDS - 1
+    _os.utime(base / bot_relay.OUTBOX_DIR / f"{stale_env['id']}.json", (old, old))
+    _os.utime(stale_reply, (old, old))
+
+    removed = bot_relay.cleanup_bot_relay_artifacts()
+
+    assert removed == 2
+    assert not (base / bot_relay.OUTBOX_DIR / f"{stale_env['id']}.json").exists()
+    assert not stale_reply.exists()
+    assert (base / bot_relay.OUTBOX_DIR / f"{fresh_env['id']}.json").exists()
+
+
+def test_cleanup_bot_relay_artifacts_missing_dir_is_zero(tmp_path, monkeypatch):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path / "nope"))
+    assert bot_relay.cleanup_bot_relay_artifacts() == 0

tests/tui_gateway/test_bot_relay_methods.py

@@ -105,3 +105,36 @@ def test_reply_roundtrip_and_id_validation(home):
 
     err = srv._methods["bot_relay.reply"](2, {"id": "../evil"})
     assert "error" in err
+
+
+def test_deliver_write_failure_still_removes_tempfile(home, monkeypatch, tmp_path):
+    """A failed payload write must not leak the relay DM tempfile."""
+    import glob
+    import os
+    import tempfile as _tempfile
+
+    made = []
+    real_mkstemp = _tempfile.mkstemp
+
+    def _tracking_mkstemp(*args, **kwargs):
+        kwargs["dir"] = str(tmp_path)
+        fd, path = real_mkstemp(*args, **kwargs)
+        made.append(path)
+        return fd, path
+
+    class _BrokenWriter:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *exc_info):
+            return False
+
+        def write(self, content):
+            raise OSError("disk full")
+
+    monkeypatch.setattr("tempfile.mkstemp", _tracking_mkstemp)
+    monkeypatch.setattr("os.fdopen", lambda *a, **k: _BrokenWriter())
+    err = srv._methods["bot_relay.deliver"](1, {"profile": "ops", "message": "x"})
+    assert "error" in err
+    assert made, "mkstemp was never reached"
+    assert not glob.glob(str(tmp_path / "hermes-relay-dm-*")), "tempfile leaked"

tools/bot_relay.py

@@ -270,18 +270,44 @@ def write_reply(
     return path
 
 
-def _sweep_stale(base: Path) -> None:
-    cutoff = time.time() - STALE_AFTER_SECONDS
+def _sweep_stale(base: Path, *, now: float | None = None) -> int:
+    cutoff = (time.time() if now is None else now) - STALE_AFTER_SECONDS
+    removed = 0
     for sub in (CLAIMED_DIR, REPLIES_DIR, OUTBOX_DIR):
         try:
             for path in (base / sub).glob("*.json"):
                 try:
                     if path.stat().st_mtime < cutoff:
                         path.unlink()
+                        removed += 1
                 except OSError:
                     continue
         except OSError:
             continue
+    return removed
+
+
+def cleanup_bot_relay_artifacts(max_age_hours: float | None = None) -> int:
+    """Sweep stale relay artifacts (envelopes/replies hold DM plaintext).
+
+    ``_sweep_stale`` otherwise runs only when the Desktop drains the outbox
+    (``claim_pending_envelopes``) — if the Desktop never reconnects, queued
+    plaintext envelopes would sit on disk forever. Same contract as the
+    ``cleanup_*_cache`` helpers so the gateway housekeeping loop can call it
+    hourly. ``max_age_hours`` is accepted for signature compatibility but the
+    relay's own ``STALE_AFTER_SECONDS`` governs staleness.
+    """
+    del max_age_hours  # relay staleness is governed by STALE_AFTER_SECONDS
+    try:
+        home = Path(os.getenv("HERMES_HOME") or os.path.expanduser("~/.hermes"))
+        root = home.parent.parent if home.parent.name == "profiles" else home
+        base = relay_root(root)
+        if not base.is_dir():
+            return 0
+        return _sweep_stale(base)
+    except Exception:
+        logger.debug("bot_relay artifact sweep failed", exc_info=True)
+        return 0
 
 
 # ── waiter (runs on the sender gateway via terminal background process) ─────

tui_gateway/methods_bot_relay.py

@@ -110,9 +110,9 @@ def _(rid, params: dict) -> dict:
             return _err(rid, 4092, f"no profile '{profile}' on this gateway")
 
         fd, tmp = tempfile.mkstemp(prefix="hermes-relay-dm-", suffix=".txt", text=True)
-        with os.fdopen(fd, "w", encoding="utf-8") as f:
-            f.write(message)
         try:
+            with os.fdopen(fd, "w", encoding="utf-8") as f:
+                f.write(message)
             proc = subprocess.run(
                 local_delivery_command(resolved, tmp),
                 capture_output=True,