Fix OAuth flow breaking MCP session initialization #490
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When remote MCP servers require OAuth authentication, the OAuth flow was being triggered during the MCP session initialization handshake. This caused the session state to become corrupted because: 1. client.Connect() starts the MCP protocol handshake 2. Initial HTTP request returns 401 Unauthorized 3. oauthTransport intercepts and runs the full OAuth flow 4. After OAuth succeeds, the retry finds the MCP session in a broken state 5. Subsequent requests fail with "400 Bad Request: broken session" This fix adds retry logic that detects "broken session" errors during initialization and automatically retries once after OAuth completes, ensuring: - OAuth completes at the HTTP transport layer first - MCP session initialization happens with authentication already in place - No permanent session corruption from the OAuth interruption The retry is limited to OAuth-related "broken session" errors to avoid masking other legitimate connection failures. Fixes the issue where OAuth-protected MCP servers (like mcp.prisma.io) would fail to initialize despite successful user authentication.
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#485 should be updated. Or we can close it and open a new issue only for prisma |
krissetto
approved these changes
Oct 15, 2025
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Fixed #485.
When remote MCP servers require OAuth authentication AND the OAuth flow is triggered during the MCP session initialization handshake. This caused the session state to become corrupted because:
This fix adds retry logic that detects "broken session" errors during initialization and automatically retries once after OAuth completes, ensuring:
The retry is limited to OAuth-related "broken session" errors to avoid masking other legitimate connection failures.
Fixes the issue where OAuth-protected MCP servers (like mcp.prisma.io) would fail to initialize despite successful user authentication.
Note: An attempt to fix the same issue was #486, but that fix broken other MCP server like atlassian.