🐛 Bugfix: Why does the VSCode extension auth flow fail with 'Failed to...

Date: 2026-02-28
Time: 20:41:34 UTC
Session: gspace1-155.3
Agent: angular
Confidence: 95%
Status: ✅ Documented

📋 Decision Context

Question:

Why does the VSCode extension auth flow fail with 'Failed to execute json on Response: Unexpected end of JSON input' after clicking Authorize Access?

Task: Fix VSCode extension auth flow JSON parsing error

🎯 Decision Made

Chosen:

Two fixes in McpAuthComponent.authorize(): (1) Added resolveBackendApiUrl() that returns absolute URL 'https://api.gograb.space/api' when page is on production (app.gograb.space), or relative '/api' for local dev (Angular proxy). (2) Changed response parsing from unconditional response.json() to response.text() + JSON.parse() with proper error handling showing a helpful message.

Options Considered:

1. Use relative URL with proxy only
2. Pass backend URL from extension via query param
3. Detect environment in component and resolve absolute URL
4. Import Angular environment config

💭 Reasoning

ROOT CAUSE: fetch('/api/auth/mcp/callback') used a relative URL. This only works in local dev where the Angular dev proxy forwards /api/* to localhost:3000. When the VSCode extension's resolveFrontendUrl() falls back to 'https://app.gograb.space' (which happens when no local frontend is detected on ports 5200/6200), the relative /api/... URL hits the Angular SPA's own origin (app.gograb.space), not the backend (api.gograb.space). The SPA returns index.html (HTML, not JSON), and response.json() throws 'Unexpected end of JSON input'. Secondary fix: parsing response as text first then JSON.parse() gives a meaningful error message instead of a cryptic one.

📁 Files Involved

• apps/gograb-space/src/app/auth/mcp-auth/mcp-auth.component.ts

🔗 Related

• Decision ID: dev_1772311294800_ps3o4np
• Session: 155
• Workspace: gspace1

Auto-generated by MCP Smart Consolidation