diff --git a/config.example.json b/config.example.json
index a26c7f0..a13b288 100644
--- a/config.example.json
+++ b/config.example.json
@@ -4,7 +4,7 @@
   "agent_file": "agents/stack-support.agent.md",
   "runbook_file": "docs/stack-support-runbook.md",
   "claude_bin": "/home/paul/.local/bin/claude",
-  "claude_model": null,
+  "claude_model": "claude-opus-4-8",
   "claude_extra_args": [],
   "agent_timeout_seconds": 1800,
 
diff --git a/maintainer.py b/maintainer.py
index 79c3225..6a5adfd 100755
--- a/maintainer.py
+++ b/maintainer.py
@@ -53,7 +53,11 @@ DEFAULTS = {
     "agent_file": "agents/stack-support.agent.md",
     "runbook_file": "docs/stack-support-runbook.md",
     "claude_bin": "/home/paul/.local/bin/claude",
-    "claude_model": None,                 # None = claude default
+    # Pin a standard 200K-window model. Leaving this None uses the account
+    # default, which may be a 1M-context ([1m]) model; once a cycle's context
+    # crosses 200K that escalates to the 1M tier and fails on subscription
+    # plans with "Usage credits are required for long context requests" (429).
+    "claude_model": "claude-opus-4-8",
     "claude_extra_args": [],
     "agent_timeout_seconds": 1800,
     "kuma_volume": "uptime-kuma-data",
@@ -242,10 +246,18 @@ def matrix_poll_admin(cfg, state):
     if not room:
         return messages
     for ev in room.get("timeline", {}).get("events", []):
-        if ev.get("type") != "m.room.message":
-            continue
         if ev.get("sender") != admin:
             continue
+        # This bot is stdlib-only and cannot do E2E encryption. If the room is
+        # encrypted, the admin's replies arrive as undecryptable m.room.encrypted
+        # events — warn loudly rather than silently ignoring the operator. The
+        # room should be created unencrypted (see register-matrix-bot.sh).
+        if ev.get("type") == "m.room.encrypted":
+            log("WARN: received an ENCRYPTED message from the admin — this bot "
+                "cannot decrypt it. The maintenance room must be unencrypted.")
+            continue
+        if ev.get("type") != "m.room.message":
+            continue
         content = ev.get("content", {})
         if content.get("msgtype") == "m.text":
             messages.append(content.get("body", "").strip())
diff --git a/register-matrix-bot.sh b/register-matrix-bot.sh
index 1a1b169..6952794 100755
--- a/register-matrix-bot.sh
+++ b/register-matrix-bot.sh
@@ -140,10 +140,14 @@ joined = api(hs + "/_matrix/client/v3/joined_rooms", token=bot_token)[1].get("jo
 if room_id and not room_id.startswith("FILLED_BY_") and room_id in joined:
     print(f"→ Re-using existing room {room_id}")
 else:
+    # NB: is_direct must be False. A direct (DM) room makes Element auto-enable
+    # E2E encryption, which this stdlib-only bot cannot decrypt — it would then
+    # silently never see the operator's replies. A plain private room stays
+    # unencrypted (Synapse does not force room encryption).
     code, body = api(hs + "/_matrix/client/v3/createRoom", {
         "name": "Stack Maintenance",
-        "topic": "semprini-core autonomous stack maintenance",
-        "preset": "trusted_private_chat", "is_direct": True,
+        "topic": "semprini-core autonomous stack maintenance (unencrypted — bot is stdlib-only)",
+        "preset": "private_chat", "is_direct": False,
         "invite": [admin_id]}, token=bot_token)
     room_id = body.get("room_id")
     if not room_id: