diff --git a/cli.py b/cli.py
index 6b62493d60c35..4de80067800d9 100644
--- a/cli.py
+++ b/cli.py
@@ -8028,6 +8028,8 @@ def process_command(self, command: str) -> bool:
             self._handle_skin_command(cmd_original)
         elif canonical == "voice":
             self._handle_voice_command(cmd_original)
+        elif canonical == "indicator":
+            self._handle_indicator_command(cmd_original)
         elif canonical == "busy":
             self._handle_busy_command(cmd_original)
         else:
@@ -9016,6 +9018,44 @@ def _handle_reasoning_command(self, cmd: str):
         else:
             _cprint(f"  {_ACCENT}✓ Reasoning effort set to '{arg}' (session only){_RST}")
 
+    def _handle_indicator_command(self, cmd: str):
+        """Handle /indicator — pick the TUI busy-indicator style.
+
+        Usage:
+            /indicator                 Show current indicator style
+            /indicator status          Show current indicator style
+            /indicator kaomoji         Use animated kaomoji faces (default)
+            /indicator emoji           Use emoji indicator
+            /indicator unicode         Use unicode (braille) spinner
+            /indicator ascii           Use plain ASCII indicator
+        """
+        valid = {"kaomoji", "emoji", "unicode", "ascii"}
+        try:
+            cfg = load_cli_config()
+            current = ((cfg.get("display") if isinstance(cfg, dict) else None) or {}).get(
+                "tui_status_indicator", "kaomoji"
+            ) or "kaomoji"
+        except Exception:
+            current = "kaomoji"
+
+        parts = cmd.strip().split(maxsplit=1)
+        if len(parts) < 2 or parts[1].strip().lower() == "status":
+            _cprint(f"  {_ACCENT}Busy indicator style: {current}{_RST}")
+            _cprint(f"  {_DIM}Usage: /indicator [kaomoji|emoji|unicode|ascii|status]{_RST}")
+            return
+
+        arg = parts[1].strip().lower()
+        if arg not in valid:
+            _cprint(f"  {_DIM}(._.) Unknown argument: {arg}{_RST}")
+            _cprint(f"  {_DIM}Usage: /indicator [kaomoji|emoji|unicode|ascii|status]{_RST}")
+            return
+
+        if save_config_value("display.tui_status_indicator", arg):
+            _cprint(f"  {_ACCENT}✓ Busy indicator style set to '{arg}' (saved to config){_RST}")
+            _cprint(f"  {_DIM}Takes effect on next CLI/TUI start.{_RST}")
+        else:
+            _cprint(f"  {_ACCENT}✓ Busy indicator style set to '{arg}' (session only){_RST}")
+
     def _handle_busy_command(self, cmd: str):
         """Handle /busy — control what Enter does while Hermes is working.
 
diff --git a/tests/hermes_cli/test_indicator_command.py b/tests/hermes_cli/test_indicator_command.py
new file mode 100644
index 0000000000000..7c5711d2d6fe4
--- /dev/null
+++ b/tests/hermes_cli/test_indicator_command.py
@@ -0,0 +1,79 @@
+"""Regression test for issue #27603: /indicator slash command had no handler.
+
+The command is defined in COMMAND_REGISTRY but `HermesCLI.process_command()`
+did not dispatch it, causing "Unknown command: /indicator <style>".
+"""
+from __future__ import annotations
+
+import importlib
+import sys
+import types
+
+import pytest
+
+
+def test_indicator_command_registered():
+    from hermes_cli.commands import COMMAND_REGISTRY, resolve_command
+
+    names = [c.name for c in COMMAND_REGISTRY]
+    assert "indicator" in names
+
+    cdef = resolve_command("indicator")
+    assert cdef is not None and cdef.name == "indicator"
+
+
+def test_indicator_handler_exists_and_dispatched():
+    """The HermesCLI class must expose _handle_indicator_command, and
+    process_command() must dispatch /indicator to it."""
+    import cli as cli_mod
+
+    assert hasattr(cli_mod.HermesCLI, "_handle_indicator_command"), (
+        "HermesCLI is missing _handle_indicator_command — /indicator will fall "
+        "through to 'Unknown command' (issue #27603)."
+    )
+
+    # Source-level check that the dispatch is wired in process_command.
+    src = cli_mod.__file__
+    with open(src, "r") as f:
+        text = f.read()
+    assert 'canonical == "indicator"' in text, (
+        "process_command() is missing the `elif canonical == \"indicator\"` branch."
+    )
+
+
+def test_indicator_handler_saves_config_value(monkeypatch):
+    """Calling _handle_indicator_command with a valid style should call
+    save_config_value('display.tui_status_indicator', <style>)."""
+    import cli as cli_mod
+
+    calls: list[tuple] = []
+
+    def fake_save(key, value):
+        calls.append((key, value))
+        return True
+
+    monkeypatch.setattr(cli_mod, "save_config_value", fake_save)
+    monkeypatch.setattr(cli_mod, "load_cli_config", lambda: {"display": {}})
+
+    # Build a minimal stand-in for `self`; the handler only uses module-level
+    # helpers, so an empty object is sufficient.
+    fake_self = types.SimpleNamespace()
+    cli_mod.HermesCLI._handle_indicator_command(fake_self, "/indicator unicode")
+
+    assert ("display.tui_status_indicator", "unicode") in calls
+
+
+def test_indicator_handler_rejects_unknown_style(monkeypatch):
+    import cli as cli_mod
+
+    calls: list[tuple] = []
+    monkeypatch.setattr(
+        cli_mod, "save_config_value",
+        lambda k, v: (calls.append((k, v)) or True),
+    )
+    monkeypatch.setattr(cli_mod, "load_cli_config", lambda: {"display": {}})
+
+    fake_self = types.SimpleNamespace()
+    cli_mod.HermesCLI._handle_indicator_command(fake_self, "/indicator bogus")
+    # Must not have saved anything for an unknown style.
+    assert calls == []