refactor: extract Copilot API resolver from cli.ts (#2624) (#2636)

Extract resolveCopilotApiKey, deriveCopilotApiTargetFromProviderBaseUrl,
deriveCopilotApiBasePathFromProviderBaseUrl, and resolveCopilotApiRouting
into src/copilot-api-resolver.ts (84 lines).

cli.ts re-exports all symbols for backwards compatibility.

All 32 cli tests pass. Build passes.

Closes #2624

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: lpcox

src/cli.ts

@@ -126,92 +126,20 @@ import {
 } from './option-parsers';
 import { processAgentImageOption } from './domain-utils';
 
-export const program = new Command();
-
-/**
- * Resolve the Copilot BYOK key from supported environment variables.
- * COPILOT_API_KEY takes precedence over COPILOT_PROVIDER_API_KEY.
- */
-export function resolveCopilotApiKey(
-  env: Record<string, string | undefined> = process.env
-): string | undefined {
-  return env.COPILOT_API_KEY || env.COPILOT_PROVIDER_API_KEY;
-}
-
-/**
- * Derive a Copilot API target hostname from COPILOT_PROVIDER_BASE_URL.
- * Returns undefined when the value is empty or not a valid URL/host.
- */
-export function deriveCopilotApiTargetFromProviderBaseUrl(
-  providerBaseUrl: string | undefined
-): string | undefined {
-  const trimmed = providerBaseUrl?.trim();
-  if (!trimmed) return undefined;
-
-  const candidate = trimmed.includes('://')
-    ? trimmed
-    : `https://${trimmed}`;
-
-  try {
-    return new URL(candidate).hostname || undefined;
-  } catch {
-    return undefined;
-  }
-}
-
-/**
- * Derive a Copilot API base-path prefix from COPILOT_PROVIDER_BASE_URL.
- * Returns undefined when the value is empty, invalid, or has no path.
- */
-export function deriveCopilotApiBasePathFromProviderBaseUrl(
-  providerBaseUrl: string | undefined
-): string | undefined {
-  const trimmed = providerBaseUrl?.trim();
-  if (!trimmed) return undefined;
-
-  const candidate = trimmed.includes('://')
-    ? trimmed
-    : `https://${trimmed}`;
+import {
+  resolveCopilotApiKey,
+  resolveCopilotApiRouting,
+} from './copilot-api-resolver';
 
-  try {
-    const pathname = new URL(candidate).pathname.replace(/\/+$/, '');
-    if (!pathname || pathname === '/') return undefined;
-    return pathname.startsWith('/') ? pathname : `/${pathname}`;
-  } catch {
-    return undefined;
-  }
-}
+// Re-export for backwards compatibility (used by cli.test.ts and other consumers)
+export {
+  resolveCopilotApiKey,
+  deriveCopilotApiTargetFromProviderBaseUrl,
+  deriveCopilotApiBasePathFromProviderBaseUrl,
+  resolveCopilotApiRouting,
+} from './copilot-api-resolver';
 
-/**
- * Resolve Copilot target/base-path routing for BYOK provider-style env vars.
- *
- * Target precedence:
- *   1. --copilot-api-target
- *   2. COPILOT_API_TARGET
- *   3. Hostname from COPILOT_PROVIDER_BASE_URL
- *
- * Base path precedence:
- *   1. COPILOT_API_BASE_PATH
- *   2. Pathname from COPILOT_PROVIDER_BASE_URL
- */
-export function resolveCopilotApiRouting(
-  options: { copilotApiTarget?: string },
-  env: Record<string, string | undefined> = process.env
-): { copilotApiTarget?: string; copilotApiBasePath?: string } {
-  const providerBaseUrl = env.COPILOT_PROVIDER_BASE_URL;
-  const copilotApiTargetFromProviderBaseUrl = deriveCopilotApiTargetFromProviderBaseUrl(providerBaseUrl);
-  const copilotApiBasePathFromProviderBaseUrl = deriveCopilotApiBasePathFromProviderBaseUrl(providerBaseUrl);
-
-  return {
-    copilotApiTarget:
-      options.copilotApiTarget ||
-      env.COPILOT_API_TARGET ||
-      copilotApiTargetFromProviderBaseUrl,
-    copilotApiBasePath:
-      env.COPILOT_API_BASE_PATH ||
-      copilotApiBasePathFromProviderBaseUrl,
-  };
-}
+export const program = new Command();
 
 // Option group markers used by the custom help formatter to insert section headers.
 // Each key is the long flag name of the first option in a group.

src/copilot-api-resolver.ts

@@ -0,0 +1,84 @@
+/**
+ * Resolve the Copilot BYOK key from supported environment variables.
+ * COPILOT_API_KEY takes precedence over COPILOT_PROVIDER_API_KEY.
+ */
+export function resolveCopilotApiKey(
+  env: Record<string, string | undefined> = process.env
+): string | undefined {
+  return env.COPILOT_API_KEY || env.COPILOT_PROVIDER_API_KEY;
+}
+
+/**
+ * Derive a Copilot API target hostname from COPILOT_PROVIDER_BASE_URL.
+ * Returns undefined when the value is empty or not a valid URL/host.
+ */
+export function deriveCopilotApiTargetFromProviderBaseUrl(
+  providerBaseUrl: string | undefined
+): string | undefined {
+  const trimmed = providerBaseUrl?.trim();
+  if (!trimmed) return undefined;
+
+  const candidate = trimmed.includes('://')
+    ? trimmed
+    : `https://${trimmed}`;
+
+  try {
+    return new URL(candidate).hostname || undefined;
+  } catch {
+    return undefined;
+  }
+}
+
+/**
+ * Derive a Copilot API base-path prefix from COPILOT_PROVIDER_BASE_URL.
+ * Returns undefined when the value is empty, invalid, or has no path.
+ */
+export function deriveCopilotApiBasePathFromProviderBaseUrl(
+  providerBaseUrl: string | undefined
+): string | undefined {
+  const trimmed = providerBaseUrl?.trim();
+  if (!trimmed) return undefined;
+
+  const candidate = trimmed.includes('://')
+    ? trimmed
+    : `https://${trimmed}`;
+
+  try {
+    const pathname = new URL(candidate).pathname.replace(/\/+$/, '');
+    if (!pathname || pathname === '/') return undefined;
+    return pathname.startsWith('/') ? pathname : `/${pathname}`;
+  } catch {
+    return undefined;
+  }
+}
+
+/**
+ * Resolve Copilot target/base-path routing for BYOK provider-style env vars.
+ *
+ * Target precedence:
+ *   1. --copilot-api-target
+ *   2. COPILOT_API_TARGET
+ *   3. Hostname from COPILOT_PROVIDER_BASE_URL
+ *
+ * Base path precedence:
+ *   1. COPILOT_API_BASE_PATH
+ *   2. Pathname from COPILOT_PROVIDER_BASE_URL
+ */
+export function resolveCopilotApiRouting(
+  options: { copilotApiTarget?: string },
+  env: Record<string, string | undefined> = process.env
+): { copilotApiTarget?: string; copilotApiBasePath?: string } {
+  const providerBaseUrl = env.COPILOT_PROVIDER_BASE_URL;
+  const copilotApiTargetFromProviderBaseUrl = deriveCopilotApiTargetFromProviderBaseUrl(providerBaseUrl);
+  const copilotApiBasePathFromProviderBaseUrl = deriveCopilotApiBasePathFromProviderBaseUrl(providerBaseUrl);
+
+  return {
+    copilotApiTarget:
+      options.copilotApiTarget ||
+      env.COPILOT_API_TARGET ||
+      copilotApiTargetFromProviderBaseUrl,
+    copilotApiBasePath:
+      env.COPILOT_API_BASE_PATH ||
+      copilotApiBasePathFromProviderBaseUrl,
+  };
+}