Fix new chats using profile default model

api/models.py

@@ -1340,6 +1340,27 @@ def get_session(sid, metadata_only=False):
         return s
     raise KeyError(sid)
 
+def _profile_default_model_state(profile=None):
+    """Return the default model/provider configured for *profile*."""
+    default_model = ""
+    default_provider = None
+    try:
+        from api.profiles import get_hermes_home_for_profile
+        config_path = Path(get_hermes_home_for_profile(profile)) / "config.yaml"
+        config_data = _cfg._load_yaml_config_file(config_path)
+    except Exception:
+        config_data = {}
+
+    model_cfg = config_data.get("model", {}) if isinstance(config_data, dict) else {}
+    if isinstance(model_cfg, str):
+        default_model = model_cfg.strip()
+    elif isinstance(model_cfg, dict):
+        default_model = str(model_cfg.get("default") or "").strip()
+        default_provider = str(model_cfg.get("provider") or "").strip() or None
+
+    return default_model or get_effective_default_model(), default_provider
+
+
 def new_session(workspace=None, model=None, profile=None, model_provider=None, project_id=None, worktree_info=None):
     """Create a new in-memory session.
 
@@ -1372,13 +1393,19 @@ def new_session(workspace=None, model=None, profile=None, model_provider=None, p
             profile = get_active_profile_name()
         except ImportError:
             profile = None
-    effective_model = model or get_effective_default_model()
+    if model:
+        effective_model = model
+        effective_model_provider = model_provider
+    else:
+        effective_model, effective_model_provider = _profile_default_model_state(profile)
+        if model_provider:
+            effective_model_provider = model_provider
     wt = worktree_info if isinstance(worktree_info, dict) else None
     workspace_path = (wt.get('path') if wt and wt.get('path') else workspace) if wt else workspace
     s = Session(
         workspace=workspace_path or get_last_workspace(),
         model=effective_model,
-        model_provider=model_provider,
+        model_provider=effective_model_provider,
         profile=profile,
         project_id=project_id,
         worktree_path=wt.get('path') if wt else None,

static/sessions.js

@@ -460,23 +460,7 @@ async function newSession(flash, options={}){
     const switchWs=S._profileSwitchWorkspace;
     S._profileSwitchWorkspace=null;
     const inheritWs=switchWs||(S.session?S.session.workspace:null)||(S._profileDefaultWorkspace||null);
-    // Use the saved default model for new sessions (#872). The user's saved
-    // default_model (from Settings) takes priority over the chat-header dropdown
-    // value, which reflects the *previous* session's model. Fall back to the
-    // dropdown value only when no default_model is configured.
-    const modelSel=$('modelSelect');
-    const selectedDefaultModel=window._defaultModel||(modelSel&&modelSel.value)||'';
-    let defaultApplied=false;
-    if(window._defaultModel&&modelSel&&typeof _applyModelToDropdown==='function'){
-      defaultApplied=!!_applyModelToDropdown(window._defaultModel,modelSel,window._activeProvider||null);
-    }
-    const canQualify=!window._defaultModel||defaultApplied||(modelSel&&modelSel.value===selectedDefaultModel);
-    const newModelState=(canQualify&&typeof _modelStateForSelect==='function')
-      ? _modelStateForSelect(modelSel,selectedDefaultModel)
-      : {model:selectedDefaultModel,model_provider:null};
     const reqBody={
-      model:newModelState.model,
-      model_provider:newModelState.model_provider||null,
       workspace:inheritWs,
       profile:S.activeProfile||'default',
     };

tests/test_issue798.py

@@ -266,6 +266,30 @@ def test_sessions_js_sends_profile_in_new_session_post():
     )
 
 
+def test_new_session_uses_explicit_profile_default_model_and_provider(tmp_path, monkeypatch):
+    """New chats must inherit the selected profile's config default."""
+    import api.profiles as p
+    import api.models as m
+
+    monkeypatch.setattr(p, "_DEFAULT_HERMES_HOME", tmp_path)
+    profile_home = tmp_path / "profiles" / "pepper"
+    profile_home.mkdir(parents=True)
+    (profile_home / "config.yaml").write_text(
+        "model:\n  default: pepper-profile-model\n  provider: pepper-provider\n",
+        encoding="utf-8",
+    )
+
+    with patch.object(m.Session, 'save', return_value=None):
+        s = m.new_session(workspace=str(tmp_path), profile="pepper")
+    try:
+        assert s.model == "pepper-profile-model"
+        assert s.model_provider == "pepper-provider"
+        assert s.profile == "pepper"
+    finally:
+        with m.LOCK:
+            m.SESSIONS.pop(s.session_id, None)
+
+
 def test_get_hermes_home_for_profile_rejects_path_traversal():
     """R19j: get_hermes_home_for_profile() must reject names that don't match
     _PROFILE_ID_RE (e.g. path traversal like '../../etc') and return the base

tests/test_provider_mismatch.py

@@ -1171,10 +1171,13 @@ class TestFrontendModelProviderState:
         assert "_modelStateForSelect" in src
         assert "model_provider:modelState.model_provider||null" in src
 
-    def test_new_session_sends_model_provider(self):
+    def test_new_session_lets_profile_config_choose_default_model_provider(self):
         src = _read("static/sessions.js")
-        assert "_modelStateForSelect(modelSel,selectedDefaultModel)" in src
-        assert "model_provider:newModelState.model_provider||null" in src
+        start = src.index("async function newSession(")
+        body = src[start:src.index("const data=await api('/api/session/new'", start)]
+        assert "profile:S.activeProfile||'default'" in body
+        assert "model:newModelState.model" not in body
+        assert "model_provider:newModelState.model_provider||null" not in body
 
     def test_ui_has_json_model_state_storage(self):
         src = _read("static/ui.js")