Add GitHub Copilot as a provider alias

Register github-copilot as an OpenAI-compatible provider alias pointing to
https://api.githubcopilot.com with GITHUB_TOKEN for authentication.

- Add alias entry in the Aliases map (pkg/model/provider)
- Update agent-schema.json with the new provider example
- Add examples/github-copilot.yaml
- Simplify provider tests to be data-driven from Aliases map,
  removing the need to update tests when adding new providers

Closes #2148

Assisted-By: docker-agent

Author: dgageot

agent-schema.json

@@ -495,7 +495,8 @@
             "openai",
             "anthropic",
             "dmr",
-            "ollama"
+            "ollama",
+            "github-copilot"
           ]
         },
         "model": {

examples/github-copilot.yaml

@@ -0,0 +1,9 @@
+#!/usr/bin/env docker agent run
+
+agents:
+  root:
+    model: github-copilot/gpt-4o
+    description: A helpful AI assistant powered by GitHub Copilot
+    instruction: |
+      You are a helpful AI assistant.
+      Be helpful, accurate, and concise in your responses.

pkg/model/provider/provider.go

@@ -124,6 +124,11 @@ var Aliases = map[string]Alias{
 		BaseURL:     "https://api.minimax.io/v1",
 		TokenEnvVar: "MINIMAX_API_KEY",
 	},
+	"github-copilot": {
+		APIType:     "openai",
+		BaseURL:     "https://api.githubcopilot.com",
+		TokenEnvVar: "GITHUB_TOKEN",
+	},
 }
 
 // Provider defines the interface for model providers

pkg/model/provider/provider_test.go

@@ -29,41 +29,23 @@ func TestCatalogProviders(t *testing.T) {
 func TestIsCatalogProvider(t *testing.T) {
 	t.Parallel()
 
-	tests := []struct {
-		name     string
-		provider string
-		want     bool
-	}{
-		// Core providers
-		{"openai is core", "openai", true},
-		{"anthropic is core", "anthropic", true},
-		{"google is core", "google", true},
-		{"dmr is core", "dmr", true},
-		{"amazon-bedrock is core", "amazon-bedrock", true},
-
-		// Aliases with BaseURL (should be included)
-		{"mistral has BaseURL", "mistral", true},
-		{"xai has BaseURL", "xai", true},
-		{"nebius has BaseURL", "nebius", true},
-		{"requesty has BaseURL", "requesty", true},
-		{"ollama has BaseURL", "ollama", true},
-		{"minimax has BaseURL", "minimax", true},
-
-		// Aliases without BaseURL (should be excluded)
-		{"azure has no BaseURL", "azure", false},
-
-		// Unknown providers
-		{"unknown provider", "unknown", false},
-		{"cohere not supported", "cohere", false},
+	// All core providers should be catalog providers
+	for _, core := range CoreProviders {
+		assert.True(t, IsCatalogProvider(core), "core provider %s should be a catalog provider", core)
 	}
 
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-			got := IsCatalogProvider(tt.provider)
-			assert.Equal(t, tt.want, got)
-		})
+	// Aliases: catalog if and only if they have a BaseURL
+	for name, alias := range Aliases {
+		if alias.BaseURL != "" {
+			assert.True(t, IsCatalogProvider(name), "alias %s with BaseURL should be a catalog provider", name)
+		} else {
+			assert.False(t, IsCatalogProvider(name), "alias %s without BaseURL should NOT be a catalog provider", name)
+		}
 	}
+
+	// Unknown providers
+	assert.False(t, IsCatalogProvider("unknown"))
+	assert.False(t, IsCatalogProvider("cohere"))
 }
 
 func TestAllProviders(t *testing.T) {

pkg/tui/dialog/model_picker_test.go

@@ -348,35 +348,19 @@ func TestValidateCustomModelSpec(t *testing.T) {
 func TestIsValidProvider(t *testing.T) {
 	t.Parallel()
 
-	tests := []struct {
-		provider string
-		want     bool
-	}{
-		{"openai", true},
-		{"anthropic", true},
-		{"google", true},
-		{"dmr", true},
-		{"mistral", true},
-		{"xai", true},
-		{"nebius", true},
-		{"ollama", true},
-		{"azure", true},
-		{"requesty", true},
-		{"minimax", true},
-		{"OPENAI", true}, // case insensitive
-		{"OpenAI", true}, // case insensitive
-		{"unknown", false},
-		{"foo", false},
-		{"", false},
+	// All known providers (core + aliases) should be valid
+	for _, name := range provider.AllProviders() {
+		assert.True(t, provider.IsKnownProvider(name), "provider %s should be known", name)
 	}
 
-	for _, tt := range tests {
-		t.Run(tt.provider, func(t *testing.T) {
-			t.Parallel()
-			got := provider.IsKnownProvider(tt.provider)
-			assert.Equal(t, tt.want, got)
-		})
-	}
+	// Case-insensitive
+	assert.True(t, provider.IsKnownProvider("OPENAI"))
+	assert.True(t, provider.IsKnownProvider("OpenAI"))
+
+	// Unknown providers
+	assert.False(t, provider.IsKnownProvider("unknown"))
+	assert.False(t, provider.IsKnownProvider("foo"))
+	assert.False(t, provider.IsKnownProvider(""))
 }
 
 func TestModelPickerSortingWithCatalog(t *testing.T) {