fix(oauth): correct OAuth implementation to match bunq documentation

ts/bunq.classes.apicontext.ts

@@ -44,15 +44,6 @@ export class BunqApiContext {
    * Initialize the API context (installation, device, session)
    */
   public async init(): Promise<void> {
-    // If using OAuth token, skip session creation
-    if (this.options.isOAuthToken) {
-      // OAuth tokens already have an associated session
-      this.context.sessionToken = this.options.apiKey;
-      this.session = new BunqSession(this.crypto, this.context);
-      this.session.setOAuthMode(true);
-      return;
-    }
-    
     // Try to load existing context
     const existingContext = await this.loadContext();
     
@@ -78,6 +69,11 @@ export class BunqApiContext {
       this.options.deviceDescription,
       this.options.permittedIps || []
     );
+    
+    // Set OAuth mode if applicable (for session expiry handling)
+    if (this.options.isOAuthToken) {
+      this.session.setOAuthMode(true);
+    }
 
     // Save context
     await this.saveContext();
@@ -135,11 +131,6 @@ export class BunqApiContext {
    * Refresh session if needed
    */
   public async ensureValidSession(): Promise<void> {
-    // OAuth tokens don't need session refresh
-    if (this.options.isOAuthToken) {
-      return;
-    }
-    
     await this.session.refreshSession();
     await this.saveContext();
   }

ts/bunq.classes.httpclient.ts

@@ -10,20 +10,12 @@ export class BunqHttpClient {
   private crypto: BunqCrypto;
   private context: IBunqApiContext;
   private requestCounter: number = 0;
-  private isOAuthMode: boolean = false;
 
   constructor(crypto: BunqCrypto, context: IBunqApiContext) {
     this.crypto = crypto;
     this.context = context;
   }
 
-  /**
-   * Set OAuth mode
-   */
-  public setOAuthMode(isOAuth: boolean): void {
-    this.isOAuthMode = isOAuth;
-  }
-
   /**
    * Update the API context (used after getting session token)
    */
@@ -44,20 +36,13 @@ export class BunqHttpClient {
     const body = options.body ? JSON.stringify(options.body) : undefined;
     
     // Add signature if required
-    // Skip signing for OAuth tokens or if explicitly disabled
-    if (options.useSigning !== false && !this.isOAuthMode) {
-      try {
-        const privateKey = this.crypto.getPrivateKey();
-        headers['X-Bunq-Client-Signature'] = this.crypto.createSignatureHeader(
-          options.method,
-          options.endpoint,
-          headers,
-          body || ''
-        );
-      } catch (error) {
-        // If no private key is available (e.g., OAuth mode), skip signing
-        // This is expected for OAuth tokens
-      }
+    if (options.useSigning !== false && this.crypto.getPrivateKey()) {
+      headers['X-Bunq-Client-Signature'] = this.crypto.createSignatureHeader(
+        options.method,
+        options.endpoint,
+        headers,
+        body || ''
+      );
     }
 
     // Make the request
@@ -81,8 +66,7 @@ export class BunqHttpClient {
       const response = await plugins.smartrequest.request(url, requestOptions);
       
       // Verify response signature if we have server public key
-      // Skip verification for OAuth tokens as they don't have installation keys
-      if (this.context.serverPublicKey && !this.isOAuthMode) {
+      if (this.context.serverPublicKey) {
         // Convert headers to string-only format
         const stringHeaders: { [key: string]: string } = {};
         for (const [key, value] of Object.entries(response.headers)) {

ts/bunq.classes.session.ts

@@ -149,8 +149,6 @@ export class BunqSession {
       // OAuth tokens don't expire in the same way as regular sessions
       // Set a far future expiry time
       this.sessionExpiryTime = plugins.smarttime.TimeStamp.fromMilliSeconds(Date.now() + 365 * 24 * 60 * 60 * 1000);
-      // Also set OAuth mode on HTTP client
-      this.httpClient.setOAuthMode(true);
     }
   }
 
@@ -158,11 +156,6 @@ export class BunqSession {
    * Check if session is still valid
    */
   public isSessionValid(): boolean {
-    // OAuth tokens are always considered valid (they have their own expiry mechanism)
-    if (this.isOAuthMode) {
-      return true;
-    }
-    
     if (!this.sessionExpiryTime) {
       return false;
     }
@@ -175,11 +168,6 @@ export class BunqSession {
    * Refresh the session if needed
    */
   public async refreshSession(): Promise<void> {
-    // OAuth tokens don't need session refresh
-    if (this.isOAuthMode) {
-      return;
-    }
-    
     if (!this.isSessionValid()) {
       await this.createSession();
     }