fix(dashboard): preserve CLI-configured custom endpoints on same-endpoint model/set

POST /api/model/set re-registered a named custom_providers row for any
custom/local main assignment, even when the endpoint was already a fact
in config.yaml (the CLI gateway setup writes provider: custom with an
inline base_url + api_mode). The picker then rewrote the CLI's shape into
custom:<slug> with base_url: '' (#76324).

Snapshot the pre-save config and skip registration when the endpoint is
already known (inline model.base_url, a providers: entry, or a
custom_providers row); only a genuinely new endpoint gets a named row.

Fixes #76324

hermes_cli/web_server_config.py

@@ -661,10 +661,41 @@ def _apply_nous_gateway_defaults(cfg: dict) -> list:
         return []
 
 
+def _endpoint_known_to_config(cfg: dict, base_url: str) -> bool:
+    """True when *base_url* is already an endpoint fact in *cfg*: the inline ``model.base_url``,
+    a ``providers.<slug>`` entry, or a ``custom_providers`` row. Comparison is trailing-slash
+    and case insensitive (``_save_custom_provider`` dedups the same way)."""
+    wanted = str(base_url or "").strip().rstrip("/").lower()
+    if not wanted:
+        return False
+
+    def _matches(value: Any) -> bool:
+        return str(value or "").strip().rstrip("/").lower() == wanted
+
+    model_cfg = cfg.get("model")
+    if isinstance(model_cfg, dict) and _matches(model_cfg.get("base_url")):
+        return True
+    for section_key in ("providers", "custom_providers"):
+        section = cfg.get(section_key)
+        entries: Any = section if isinstance(section, list) else (
+            list(section.values()) if isinstance(section, dict) else [])
+        for entry in entries:
+            if isinstance(entry, dict) and _matches(entry.get("base_url") or entry.get("url") or entry.get("api")):
+                return True
+    return False
+
+
 def _register_custom_endpoint(base_url: str, api_key: str, model: str) -> None:
     """Register a named ``custom_providers`` entry for a custom/local endpoint (mirrors the
     ``hermes model`` custom flow) so the picker gets a proper ready row instead of a "needs
-    setup" dead-end. Dedups by base_url; never blocks the already-persisted assignment."""
+    setup" dead-end. Dedups by base_url; never blocks the already-persisted assignment.
+
+    SKIPPED when the endpoint is already a fact in the config (#76324): the CLI gateway setup
+    writes ``provider: custom`` with an inline ``base_url`` + ``api_mode``, and re-registering
+    that same endpoint as a named ``custom:<slug>`` row on every dashboard re-save is what let
+    the picker rewrite the CLI's shape into ``custom:<slug>`` + ``base_url: ''``. Only a
+    GENUINELY new endpoint gets a named row.
+    """
     try:
         from hermes_cli.main_provider_setup import _auto_provider_name, _save_custom_provider
 
@@ -728,6 +759,13 @@ def _apply_main_assignment_sync(cfg: dict, provider: str, model: str, base_url:
     base_url, result = prepared or _prepare_main_assignment(cfg, provider, model, base_url, api_key)
     provider, model = result.target_provider, result.new_model
     provider_entry = _provider_entry(cfg, provider)
+    # Snapshot BEFORE the new assignment overwrites cfg["model"]: this is the state the user
+    # (CLI setup, a prior dashboard save) already had on disk, and it decides whether the
+    # endpoint is genuinely NEW (register a named custom_providers row) or already known
+    # (keep the existing shape — #76324).
+    provider_lc = provider.strip().lower()
+    endpoint_already_known = (
+        provider_lc in {"custom", "local"} and bool(base_url) and _endpoint_known_to_config(cfg, base_url))
     model_cfg = _apply_main_model_assignment(cfg.get("model", {}), result, api_key)
     _resolve_assignment_credentials(model_cfg, provider, provider_entry)
     cfg["model"] = model_cfg
@@ -735,7 +773,7 @@ def _apply_main_assignment_sync(cfg: dict, provider: str, model: str, base_url:
     new_provider = provider.strip().lower()
     gateway_tools = _apply_nous_gateway_defaults(cfg) if new_provider == "nous" else []
     save_config(cfg)
-    if new_provider in {"custom", "local"} and base_url:
+    if new_provider in {"custom", "local"} and base_url and not endpoint_already_known:
         _register_custom_endpoint(base_url, api_key, model)
     # The serve process's boot record may still say "nothing configured"; the chat gates on it.
     reconcile_record()

tests/hermes_cli/test_model_set_preserve_custom_endpoint.py

@@ -0,0 +1,82 @@
+"""Red test for #76324: POST /api/model/set preserving a CLI-configured bare ``custom`` endpoint.
+
+The CLI gateway setup writes::
+
+    model:
+      default: gemma4:latest
+      provider: custom
+      base_url: http://10.0.0.155:11434/v1
+      api_mode: chat_completions
+
+Re-saving the SAME endpoint through the dashboard must leave this shape on disk
+untouched: no ``custom:<slug>`` provider rewrite, no empty ``base_url: ''``,
+no auto-registered ``custom_providers`` entry.
+"""
+
+import importlib
+import sys
+
+import pytest
+
+
+@pytest.fixture()
+def isolated_home(tmp_path, monkeypatch):
+    home = tmp_path / ".hermes"
+    home.mkdir()
+    monkeypatch.setenv("HERMES_HOME", str(home))
+    import hermes_cli.config as config_mod
+
+    importlib.reload(config_mod)
+    yield home
+    importlib.reload(config_mod)
+
+
+def _write_cli_config(home):
+    (home / "config.yaml").write_text(
+        "model:\n"
+        "  default: gemma4:latest\n"
+        "  provider: custom\n"
+        "  base_url: http://10.0.0.155:11434/v1\n"
+        "  api_mode: chat_completions\n",
+        encoding="utf-8",
+    )
+
+
+def _model_cfg(home):
+    import hermes_yaml as yaml
+
+    return (yaml.safe_load((home / "config.yaml").read_text(encoding="utf-8")) or {}).get("model", {})
+
+
+def test_same_endpoint_model_set_preserves_bare_custom_block(isolated_home):
+    from hermes_cli.web_server_config import _apply_model_assignment_sync
+
+    _write_cli_config(isolated_home)
+    # Dashboard re-save of the same endpoint (base_url sent along).
+    _apply_model_assignment_sync(
+        "main", "custom", "gemma4:latest", "", "http://10.0.0.155:11434/v1", "")
+    model = _model_cfg(isolated_home)
+    assert model.get("default") == "gemma4:latest"
+    assert model.get("provider") == "custom"
+    assert model.get("base_url") == "http://10.0.0.155:11434/v1"
+    assert model.get("api_mode") == "chat_completions"
+    raw = (isolated_home / "config.yaml").read_text(encoding="utf-8")
+    assert "custom_providers" not in raw
+
+
+def test_new_endpoint_model_set_still_registers_named_provider(isolated_home):
+    """The guard must not over-fix: introducing a GENUINELY new custom endpoint through the
+    dashboard still registers a named ``custom_providers`` row (the picker's ready row)."""
+    import hermes_yaml as yaml
+
+    from hermes_cli.web_server_config import _apply_model_assignment_sync
+
+    _write_cli_config(isolated_home)
+    _apply_model_assignment_sync(
+        "main", "custom", "other-model", "", "http://192.168.1.50:11434/v1", "")
+
+    cfg = yaml.safe_load((isolated_home / "config.yaml").read_text(encoding="utf-8")) or {}
+    entries = [e for e in (cfg.get("custom_providers") or []) if isinstance(e, dict)]
+    assert any(e.get("base_url") == "http://192.168.1.50:11434/v1" for e in entries)
+    # The model block now points at the new endpoint, not the old one.
+    assert _model_cfg(isolated_home).get("base_url") == "http://192.168.1.50:11434/v1"