fix(cli): narrow Nous Hermes non-agentic warning to actual hermes-3/-4 models

The startup warning that Nous Research Hermes 3 & 4 models are not agentic
fired on any model whose name contained "hermes" anywhere, via a plain
substring check. That false-positived on unrelated local Modelfiles such
as `hermes-brain:qwen3-14b-ctx16k` — a tool-capable Qwen3 wrapper that
happens to live under a custom "hermes" tag namespace — making the warning
noise for legitimate setups.

Replace the substring check with a narrow regex anchored on `^`, `/`, or
`:` boundaries that only matches the real Hermes-3 / Hermes-4 chat family
(e.g. `NousResearch/Hermes-3-Llama-3.1-70B`, `hermes-4-405b`,
`openrouter/hermes3:70b`). Consolidate into a single helper
`is_nous_hermes_non_agentic()` in `hermes_cli.model_switch` so the CLI
and the canonical check don't drift, and route the duplicate inline site
in `cli.HermesCLI._print_warnings()` through the helper.

Add a parametrized test covering positive matches (real Hermes-3/-4
names) and a broad set of negatives (custom Modelfiles, Qwen/Claude/GPT,
older Nous-Hermes-2 families, bare "hermes", empty string, and the
"brain-hermes-3-impostor" boundary case).

hermes_cli/model_switch.py

@@ -21,6 +21,7 @@ OpenRouter variant suffixes (``:free``, ``:extended``, ``:fast``).
 from __future__ import annotations
 
 import logging
+import re
 from dataclasses import dataclass
 from typing import List, NamedTuple, Optional
 
@@ -57,10 +58,36 @@ _HERMES_MODEL_WARNING = (
     "(Claude, GPT, Gemini, DeepSeek, etc.)."
 )
 
+# Match only the real Nous Research Hermes 3 / Hermes 4 chat families.
+# The previous substring check (`"hermes" in name.lower()`) false-positived on
+# unrelated local Modelfiles like ``hermes-brain:qwen3-14b-ctx16k`` that just
+# happen to carry "hermes" in their tag but are fully tool-capable.
+#
+# Positive examples the regex must match:
+#   NousResearch/Hermes-3-Llama-3.1-70B, hermes-4-405b, openrouter/hermes3:70b
+# Negative examples it must NOT match:
+#   hermes-brain:qwen3-14b-ctx16k, qwen3:14b, claude-opus-4-6
+_NOUS_HERMES_NON_AGENTIC_RE = re.compile(
+    r"(?:^|[/:])hermes[-_ ]?[34](?:[-_.:]|$)",
+    re.IGNORECASE,
+)
+
+
+def is_nous_hermes_non_agentic(model_name: str) -> bool:
+    """Return True if *model_name* is a real Nous Hermes 3/4 chat model.
+
+    Used to decide whether to surface the non-agentic warning at startup.
+    Callers in :mod:`cli.py` and here should go through this single helper
+    so the two sites don't drift.
+    """
+    if not model_name:
+        return False
+    return bool(_NOUS_HERMES_NON_AGENTIC_RE.search(model_name))
+
 
 def _check_hermes_model_warning(model_name: str) -> str:
-    """Return a warning string if *model_name* looks like a Hermes LLM model."""
-    if "hermes" in model_name.lower():
+    """Return a warning string if *model_name* is a Nous Hermes 3/4 chat model."""
+    if is_nous_hermes_non_agentic(model_name):
         return _HERMES_MODEL_WARNING
     return ""