fix: Allow all models when COPILOT_PROVIDER_BASE_URL is set

src/commands/validators/config-assembly.test.ts

@@ -823,6 +823,53 @@ describe('config-assembly', () => {
       );
     });
 
+    it('should allow custom COPILOT_MODEL values in BYOK mode with a provider base URL', () => {
+      mockBuildConfigOnce({
+        copilotProviderApiKey: 'byok-api-key-for-azure-foundry',
+        copilotProviderBaseUrl: 'https://example-resource.openai.azure.com/openai/deployments/o4-mini-aw',
+        additionalEnv: { COPILOT_MODEL: 'o4-mini-aw' },
+      });
+
+      const agentOptions = createMinimalAgentOptions();
+      agentOptions.additionalEnv = { COPILOT_MODEL: 'o4-mini-aw' };
+
+      const result = assembleAndValidateConfig(
+        {},
+        'echo test',
+        createMinimalLogAndLimits(),
+        createMinimalNetworkOptions(),
+        agentOptions,
+      );
+
+      expect(logger.error).not.toHaveBeenCalled();
+      expect(result.additionalEnv?.COPILOT_MODEL).toBe('o4-mini-aw');
+    });
+
+    it('should allow custom COPILOT_MODEL values when provider base URL is set via env file', () => {
+      const envFilePath = path.join(testDir, 'byok.env');
+      fs.writeFileSync(envFilePath, 'COPILOT_PROVIDER_BASE_URL=https://example-resource.openai.azure.com/openai/deployments/o4-mini-aw\n');
+
+      mockBuildConfigOnce({
+        copilotProviderApiKey: 'byok-api-key-for-azure-foundry',
+        envFile: envFilePath,
+        additionalEnv: { COPILOT_MODEL: 'o4-mini-aw' },
+      });
+
+      const agentOptions = createMinimalAgentOptions();
+      agentOptions.additionalEnv = { COPILOT_MODEL: 'o4-mini-aw' };
+
+      const result = assembleAndValidateConfig(
+        {},
+        'echo test',
+        createMinimalLogAndLimits(),
+        createMinimalNetworkOptions(),
+        agentOptions,
+      );
+
+      expect(logger.error).not.toHaveBeenCalled();
+      expect(result.additionalEnv?.COPILOT_MODEL).toBe('o4-mini-aw');
+    });
+
     it('should log normalization when COPILOT_MODEL casing is adjusted', () => {
       mockBuildConfigOnce({
         copilotGithubToken: 'github_pat_testtoken',

src/commands/validators/config-assembly.ts

@@ -44,9 +44,10 @@ export function assembleAndValidateConfig(
   networkOptions: NetworkOptionsResult,
   agentOptions: AgentOptionsResult,
 ): WrapperConfig {
-  const readCopilotModelFromEnvFiles = (envFile: unknown): string | undefined => {
+  const readEnvVarFromEnvFiles = (envFile: unknown, key: string): string | undefined => {
     const envFiles = Array.isArray(envFile) ? envFile : envFile ? [envFile] : [];
     let lastSeen: string | undefined;
+    const pattern = new RegExp(`^(?:export\\s+)?${key}\\s*=\\s*(.*)$`);
     for (const candidate of envFiles) {
       if (typeof candidate !== 'string' || candidate.trim() === '') continue;
       try {
@@ -57,7 +58,7 @@ export function assembleAndValidateConfig(
         for (const line of envFileContents.split(/\r?\n/)) {
           const trimmedLine = line.trim();
           if (!trimmedLine || trimmedLine.startsWith('#')) continue;
-          const match = trimmedLine.match(/^(?:export\s+)?COPILOT_MODEL\s*=\s*(.*)$/);
+          const match = trimmedLine.match(pattern);
           if (match) {
             lastSeen = match[1]?.trim() || '';
           }
@@ -69,6 +70,10 @@ export function assembleAndValidateConfig(
     return lastSeen;
   };
 
+  const readCopilotModelFromEnvFiles = (envFile: unknown): string | undefined => {
+    return readEnvVarFromEnvFiles(envFile, 'COPILOT_MODEL');
+  };
+
   // --- Config assembly -----------------------------------------------------
 
   const config = buildConfig({
@@ -276,7 +281,17 @@ export function assembleAndValidateConfig(
     logger.warn.bind(logger),
   );
 
-  if (copilotModel && (config.copilotGithubToken || config.copilotProviderApiKey)) {
+  const hasCustomCopilotProviderBaseUrl = !!(
+    config.copilotProviderBaseUrl ||
+    config.additionalEnv?.COPILOT_PROVIDER_BASE_URL ||
+    readEnvVarFromEnvFiles((config as { envFile?: unknown }).envFile, 'COPILOT_PROVIDER_BASE_URL') ||
+    (config.envAll ? process.env.COPILOT_PROVIDER_BASE_URL : undefined)
+  );
+  if (
+    copilotModel &&
+    !hasCustomCopilotProviderBaseUrl &&
+    (config.copilotGithubToken || config.copilotProviderApiKey)
+  ) {
     const validation = validateCopilotModel(copilotModel);
     if (!validation.valid) {
       logger.error(validation.message);