fix(discord): cap slash commands at Discord's 100-command limit

plugins/platforms/discord/adapter.py

@@ -31,6 +31,12 @@
 _DISCORD_COMMAND_SYNC_STATE_FILENAME = "discord_command_sync_state.json"
 _DISCORD_COMMAND_SYNC_MUTATION_INTERVAL_SECONDS = 4.5
 _DISCORD_COMMAND_SYNC_MAX_RATE_LIMIT_SLEEP_SECONDS = 30.0
+# Discord enforces a hard cap of 100 global application (slash) commands per
+# app. Registering more makes the ENTIRE sync fail with error 30032
+# ("Maximum number of application commands reached"), which silently breaks
+# every slash command — not just the overflow ones. We keep the desired set
+# at or below this limit at registration time.
+_DISCORD_MAX_APP_COMMANDS = 100
 
 try:
     import discord
@@ -3518,6 +3524,11 @@ async def _handler(interaction: discord.Interaction):
             )
 
         already_registered: set[str] = set()
+        # Native commands above are registered first and are the highest
+        # priority, so they always survive the 100-command cap. Reserve one
+        # slot for the consolidated ``/skill`` group registered further below.
+        slot_cap = _DISCORD_MAX_APP_COMMANDS - 1
+        dropped_over_cap = 0
         try:
             from hermes_cli.commands import COMMAND_REGISTRY, _is_gateway_available, _resolve_config_gates
 
@@ -3535,6 +3546,9 @@ async def _handler(interaction: discord.Interaction):
                 discord_name = cmd_def.name.lower()[:32]
                 if discord_name in already_registered:
                     continue
+                if len(already_registered) >= slot_cap:
+                    dropped_over_cap += 1
+                    continue
                 auto_cmd = _build_auto_slash_command(
                     cmd_def.name,
                     cmd_def.description,
@@ -3567,6 +3581,9 @@ async def _handler(interaction: discord.Interaction):
                 discord_name = plugin_name.lower()[:32]
                 if discord_name in already_registered:
                     continue
+                if len(already_registered) >= slot_cap:
+                    dropped_over_cap += 1
+                    continue
                 auto_cmd = _build_auto_slash_command(
                     plugin_name,
                     plugin_desc,
@@ -3589,6 +3606,20 @@ async def _handler(interaction: discord.Interaction):
         # supporting up to 25 categories × 25 skills = 625 skills.
         self._register_skill_group(tree)
 
+        if dropped_over_cap:
+            # Staying under the cap keeps the whole sync succeeding; without
+            # this guard a single over-limit command makes Discord reject the
+            # entire batch (error 30032), breaking every slash command.
+            logger.warning(
+                "[%s] Reached Discord's limit of %d slash commands; skipped %d "
+                "lower-priority command(s) to keep the command sync working. "
+                "Disable slash commands you don't need or trim installed plugins "
+                "to surface them all.",
+                self.name,
+                _DISCORD_MAX_APP_COMMANDS,
+                dropped_over_cap,
+            )
+
         # Optional defense-in-depth: hide every slash command from non-admin
         # guild members in Discord's slash picker. Server-side authorization
         # (``_check_slash_authorization``) is the actual gate; this is purely

tests/gateway/test_discord_slash_commands.py

@@ -292,6 +292,58 @@ async def test_plugin_command_name_conflict_skipped(adapter):
     )
 
 
+# ------------------------------------------------------------------
+# 100-command cap (Discord error 30032 guard)
+# ------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_slash_command_registration_stays_under_discord_limit(adapter):
+    """Registering far more commands than Discord allows must NOT push the
+    tree over the 100-command hard cap.
+
+    Discord rejects the ENTIRE command sync with error 30032 once the
+    desired set exceeds 100 global application commands, silently breaking
+    every slash command. The adapter must bound the desired set instead.
+    Regression guard for samuraiheart's recurring
+    "Maximum number of application commands reached (100)" sync failures.
+    """
+    from plugins.platforms.discord.adapter import _DISCORD_MAX_APP_COMMANDS
+
+    adapter._run_simple_slash = AsyncMock()
+
+    # 200 plugin commands — way past Discord's limit on their own.
+    many_plugins = {
+        f"plug{i:03d}": {
+            "handler": lambda _a: "ok",
+            "description": f"Plugin command {i}",
+            "args_hint": "",
+            "plugin": "stress-plugin",
+        }
+        for i in range(200)
+    }
+
+    with patch("hermes_cli.plugins.get_plugin_commands", return_value=many_plugins):
+        adapter._register_slash_commands()
+
+    tree_names = set(adapter._client.tree.commands.keys())
+
+    # Contract: never exceed Discord's hard cap.
+    assert len(tree_names) <= _DISCORD_MAX_APP_COMMANDS, (
+        f"registered {len(tree_names)} commands — exceeds Discord's "
+        f"{_DISCORD_MAX_APP_COMMANDS} limit and would fail sync with 30032"
+    )
+
+    # Native, high-priority commands are registered first and must survive
+    # the cap — they are the core UX, not droppable overflow.
+    for native in ("status", "stop", "new", "model", "help"):
+        assert native in tree_names, f"/{native} (native) was dropped by the cap"
+
+    # The cap must actually have dropped overflow — not every plugin fit.
+    registered_plugins = [n for n in tree_names if n.startswith("plug")]
+    assert len(registered_plugins) < 200, "cap did not drop any overflow commands"
+
+
 # ------------------------------------------------------------------
 # _handle_thread_create_slash — success, session dispatch, failure
 # ------------------------------------------------------------------