diff --git a/tests/test_tui_gateway_server.py b/tests/test_tui_gateway_server.py
index 43a368ce81..1610c52939 100644
--- a/tests/test_tui_gateway_server.py
+++ b/tests/test_tui_gateway_server.py
@@ -112,6 +112,9 @@ def test_startup_runtime_does_not_treat_inference_provider_as_explicit(monkeypat
     monkeypatch.setenv("HERMES_MODEL", "nous/hermes-test")
     monkeypatch.delenv("HERMES_TUI_PROVIDER", raising=False)
     monkeypatch.setenv("HERMES_INFERENCE_PROVIDER", "nous")
+    monkeypatch.setattr(
+        server, "_detect_static_provider_for_model", lambda model, provider: None
+    )
 
     assert server._resolve_startup_runtime() == ("nous/hermes-test", None)
 
@@ -127,7 +130,7 @@ def test_startup_runtime_detects_provider_for_model_env(monkeypatch):
         assert current_provider == "auto"
         return "anthropic", "anthropic/claude-sonnet-4.6"
 
-    monkeypatch.setattr("hermes_cli.models.detect_provider_for_model", fake_detect)
+    monkeypatch.setattr(server, "_detect_static_provider_for_model", fake_detect)
 
     assert server._resolve_startup_runtime() == (
         "anthropic/claude-sonnet-4.6",
@@ -135,6 +138,22 @@ def test_startup_runtime_detects_provider_for_model_env(monkeypatch):
     )
 
 
+def test_startup_runtime_does_not_call_network_detector(monkeypatch):
+    monkeypatch.setenv("HERMES_MODEL", "sonnet")
+    monkeypatch.delenv("HERMES_TUI_PROVIDER", raising=False)
+    monkeypatch.delenv("HERMES_INFERENCE_PROVIDER", raising=False)
+    monkeypatch.setattr(server, "_load_cfg", lambda: {"model": {"provider": "auto"}})
+    monkeypatch.setattr(
+        "hermes_cli.models.detect_provider_for_model",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(AssertionError("network detector called")),
+    )
+
+    model, provider = server._resolve_startup_runtime()
+
+    assert model
+    assert provider in {None, "anthropic"}
+
+
 def _session(agent=None, **extra):
     return {
         "agent": agent if agent is not None else types.SimpleNamespace(),
diff --git a/tui_gateway/server.py b/tui_gateway/server.py
index 9f188de645..557fec19c2 100644
--- a/tui_gateway/server.py
+++ b/tui_gateway/server.py
@@ -574,6 +574,48 @@ def _resolve_model() -> str:
     return "anthropic/claude-sonnet-4"
 
 
+def _detect_static_provider_for_model(model_name: str, current_provider: str) -> tuple[str, str] | None:
+    """Startup-safe provider detection: static catalogs only, no network fetches."""
+    name = (model_name or "").strip()
+    if not name:
+        return None
+
+    try:
+        from hermes_cli.models import (
+            _PROVIDER_ALIASES,
+            _PROVIDER_LABELS,
+            _PROVIDER_MODELS,
+            normalize_provider,
+        )
+    except Exception:
+        return None
+
+    name_lower = name.lower()
+    normalized_current = normalize_provider(current_provider)
+    resolved_provider = _PROVIDER_ALIASES.get(name_lower, name_lower)
+    if resolved_provider not in {"custom", "openrouter"}:
+        default_models = _PROVIDER_MODELS.get(resolved_provider, [])
+        if (
+            resolved_provider in _PROVIDER_LABELS
+            and default_models
+            and resolved_provider != normalized_current
+        ):
+            return resolved_provider, default_models[0]
+
+    aggregators = {"nous", "openrouter", "ai-gateway", "copilot", "kilocode"}
+    current_models = _PROVIDER_MODELS.get(normalized_current, [])
+    if any(name_lower == m.lower() for m in current_models):
+        return None
+
+    for provider, models in _PROVIDER_MODELS.items():
+        if provider == normalized_current or provider in aggregators:
+            continue
+        if any(name_lower == m.lower() for m in models):
+            return provider, name
+
+    return None
+
+
 def _resolve_startup_runtime() -> tuple[str, str | None]:
     model = _resolve_model()
     explicit_provider = os.environ.get("HERMES_TUI_PROVIDER", "").strip()
@@ -588,15 +630,13 @@ def _resolve_startup_runtime() -> tuple[str, str | None]:
         return model, None
 
     try:
-        from hermes_cli.models import detect_provider_for_model
-
         cfg = _load_cfg().get("model") or {}
         current_provider = (
             str(cfg.get("provider") or "").strip().lower()
             if isinstance(cfg, dict)
             else ""
         ) or os.environ.get("HERMES_INFERENCE_PROVIDER", "").strip().lower() or "auto"
-        detected = detect_provider_for_model(explicit_model, current_provider)
+        detected = _detect_static_provider_for_model(explicit_model, current_provider)
         if detected:
             provider, detected_model = detected
             return detected_model, provider