fix: surface actual server error in OAuth code exchange UI

AGENTS.md

@@ -0,0 +1,21 @@
+# AGENTS.md — ai-provider-for-anthropic-max
+
+WordPress plugin.
+
+## Local Development Environment
+
+The shared WordPress dev install for testing this plugin is at `../wordpress` (relative to this repo root).
+
+- **URL**: http://wordpress.local:8080
+- **Admin**: http://wordpress.local:8080/wp-admin — `admin` / `admin`
+- **WordPress version**: 7.0-RC2
+- **This plugin**: symlinked into `../wordpress/wp-content/plugins/$(basename $PWD)`
+- **Reset to clean state**: `cd ../wordpress && ./reset.sh`
+
+WP-CLI is configured via `wp-cli.yml` in this repo root — run `wp` commands directly from here without specifying `--path`.
+
+```bash
+wp plugin activate $(basename $PWD)   # activate this plugin
+wp plugin deactivate $(basename $PWD) # deactivate
+wp db reset --yes && cd ../wordpress && ./reset.sh  # full reset
+```

inc/admin.php

@@ -23,16 +23,21 @@
  * is loaded only where it is needed.
  */
 function enqueue_connector_module(): void {
+	$asset_file = __DIR__ . '/../build/connector.js';
+	$version     = file_exists( $asset_file )
+		? filemtime( $asset_file )
+		: ANTHROPIC_MAX_AI_PROVIDER_VERSION;
+
 	wp_register_script_module(
 		'ai-provider-for-anthropic-max',
-		plugins_url( 'build/connector.js', __DIR__ ),
+		ANTHROPIC_MAX_AI_PROVIDER_URL . 'build/connector.js',
 		[
 			[
 				'id'     => '@wordpress/connectors',
 				'import' => 'static',
 			],
 		],
-		ANTHROPIC_MAX_AI_PROVIDER_VERSION
+		$version
 	);
 	wp_enqueue_script_module( 'ai-provider-for-anthropic-max' );
 }

js/connector.jsx

@@ -178,11 +178,9 @@ function AddAccountForm( { onComplete, onCancel } ) {
 			window.open( data.authorize_url, '_blank', 'noopener' );
 			setStep( 'code' );
 		} catch ( err ) {
-			setError(
-				err instanceof Error
-					? err.message
-					: __( 'Failed to start OAuth flow.' )
-			);
+			// apiFetch throws a plain object {code, message, data} for WP_Error responses,
+			// not an Error instance. Use err?.message to surface the actual server message.
+			setError( err?.message || __( 'Failed to start OAuth flow.' ) );
 		} finally {
 			setIsBusy( false );
 		}
@@ -207,11 +205,9 @@ function AddAccountForm( { onComplete, onCancel } ) {
 			} );
 			onComplete();
 		} catch ( err ) {
-			setError(
-				err instanceof Error
-					? err.message
-					: __( 'Code exchange failed.' )
-			);
+			// apiFetch throws a plain object {code, message, data} for WP_Error responses,
+			// not an Error instance. Use err?.message to surface the actual server message.
+			setError( err?.message || __( 'Code exchange failed.' ) );
 		} finally {
 			setIsBusy( false );
 		}

plugin.php

@@ -24,6 +24,7 @@
 }
 
 define( 'ANTHROPIC_MAX_AI_PROVIDER_VERSION', '1.0.0' );
+define( 'ANTHROPIC_MAX_AI_PROVIDER_URL', plugin_dir_url( __FILE__ ) );
 
 // ---------------------------------------------------------------------------
 // PSR-4 autoloader for src/ classes.

src/OAuthPool/PoolManager.php

@@ -705,16 +705,25 @@ public function exchangeCode(string $code, string $state, string $email): ?array
         );
 
         if (is_wp_error($response)) {
+            if (defined('WP_DEBUG') && WP_DEBUG) {
+                error_log('[AnthropicMax] Token exchange wp_error: ' . $response->get_error_message());
+            }
             return null;
         }
 
         $status = wp_remote_retrieve_response_code($response);
         if ($status !== 200) {
+            if (defined('WP_DEBUG') && WP_DEBUG) {
+                error_log('[AnthropicMax] Token exchange HTTP ' . $status . ': ' . wp_remote_retrieve_body($response));
+            }
             return null;
         }
 
         $data = json_decode(wp_remote_retrieve_body($response), true);
         if (!is_array($data) || empty($data['access_token'])) {
+            if (defined('WP_DEBUG') && WP_DEBUG) {
+                error_log('[AnthropicMax] Token exchange bad response body: ' . wp_remote_retrieve_body($response));
+            }
             return null;
         }
 

wp-cli.yml

@@ -0,0 +1,2 @@
+path: ../wordpress
+url: http://wordpress.local:8080