fix: OAuth token refresh failure returns undefined instead of throwing

When OAuth refresh fails during model discovery, getApiKey() now returns
undefined instead of throwing. This allows the app to start and fall back
to other providers, so the user can /login to re-authenticate.

fixes #498

packages/coding-agent/src/main.ts

@@ -171,12 +171,35 @@ function getChangelogForDisplay(parsed: Args, settingsManager: SettingsManager):
 	return undefined;
 }
 
+/**
+ * Resolve a session argument to a file path.
+ * If it looks like a path, use as-is. Otherwise try to match as session ID prefix.
+ */
+function resolveSessionPath(sessionArg: string, cwd: string, sessionDir?: string): string {
+	// If it looks like a file path, use as-is
+	if (sessionArg.includes("/") || sessionArg.includes("\\") || sessionArg.endsWith(".jsonl")) {
+		return sessionArg;
+	}
+
+	// Try to match as session ID (full or partial UUID)
+	const sessions = SessionManager.list(cwd, sessionDir);
+	const matches = sessions.filter((s) => s.id.startsWith(sessionArg));
+
+	if (matches.length >= 1) {
+		return matches[0].path; // Already sorted by modified time (most recent first)
+	}
+
+	// No match - return original (will create new session)
+	return sessionArg;
+}
+
 function createSessionManager(parsed: Args, cwd: string): SessionManager | undefined {
 	if (parsed.noSession) {
 		return SessionManager.inMemory();
 	}
 	if (parsed.session) {
-		return SessionManager.open(parsed.session, parsed.sessionDir);
+		const resolvedPath = resolveSessionPath(parsed.session, cwd, parsed.sessionDir);
+		return SessionManager.open(resolvedPath, parsed.sessionDir);
 	}
 	if (parsed.continue) {
 		return SessionManager.continueRecent(cwd, parsed.sessionDir);