diff --git a/nanobot/cli/commands.py b/nanobot/cli/commands.py
index 92c017e..e540b27 100644
--- a/nanobot/cli/commands.py
+++ b/nanobot/cli/commands.py
@@ -155,21 +155,21 @@ def main(
 @app.command()
 def onboard():
     """Initialize nanobot configuration and workspace."""
-    from nanobot.config.loader import get_config_path, save_config
+    from nanobot.config.loader import get_config_path, load_config, save_config
     from nanobot.config.schema import Config
     from nanobot.utils.helpers import get_workspace_path
     
     config_path = get_config_path()
     
     if config_path.exists():
-        console.print(f"[yellow]Config already exists at {config_path}[/yellow]")
-        if not typer.confirm("Overwrite?"):
-            raise typer.Exit()
-    
-    # Create default config
-    config = Config()
-    save_config(config)
-    console.print(f"[green]✓[/green] Created config at {config_path}")
+        # Load existing config — Pydantic fills in defaults for any new fields
+        config = load_config()
+        save_config(config)
+        console.print(f"[green]✓[/green] Config refreshed at {config_path} (existing values preserved)")
+    else:
+        config = Config()
+        save_config(config)
+        console.print(f"[green]✓[/green] Created config at {config_path}")
     
     # Create workspace
     workspace = get_workspace_path()
diff --git a/nanobot/config/schema.py b/nanobot/config/schema.py
index ef999b7..60bbc69 100644
--- a/nanobot/config/schema.py
+++ b/nanobot/config/schema.py
@@ -179,6 +179,7 @@ class ProviderConfig(BaseModel):
 
 class ProvidersConfig(BaseModel):
     """Configuration for LLM providers."""
+    custom: ProviderConfig = Field(default_factory=ProviderConfig)  # Any OpenAI-compatible endpoint
     anthropic: ProviderConfig = Field(default_factory=ProviderConfig)
     openai: ProviderConfig = Field(default_factory=ProviderConfig)
     openrouter: ProviderConfig = Field(default_factory=ProviderConfig)
diff --git a/nanobot/providers/registry.py b/nanobot/providers/registry.py
index fdd036e..b9071a0 100644
--- a/nanobot/providers/registry.py
+++ b/nanobot/providers/registry.py
@@ -62,6 +62,20 @@ class ProviderSpec:
 
 PROVIDERS: tuple[ProviderSpec, ...] = (
 
+    # === Custom (user-provided OpenAI-compatible endpoint) =================
+    # No auto-detection — only activates when user explicitly configures "custom".
+
+    ProviderSpec(
+        name="custom",
+        keywords=(),
+        env_key="OPENAI_API_KEY",
+        display_name="Custom",
+        litellm_prefix="openai",
+        skip_prefixes=("openai/",),
+        is_gateway=True,
+        strip_model_prefix=True,
+    ),
+
     # === Gateways (detected by api_key / api_base, not model name) =========
     # Gateways can route any model, so they win in fallback.