[Bug] Double URL encoding in OAuth MCP server authentication

Bug Description
it looks like claude code is double-encoding some url as part of the oath process to authenticate to an mcp server?

Environment Info

• Platform: darwin
• Terminal: vscode
• Version: 2.1.6
• Feedback ID: c0357945-1d5d-4c07-9fa8-ed7209ee41d8

Errors

[{"error":"Error: Plugin path not found: /Users/herbcaudill/.claude/plugins/marketplaces/claude-plugins-official/plugins/code-review\n    at p57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:6240)\n    at d57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:5802)\n    at async file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:14659","timestamp":"2026-01-18T21:15:51.711Z"},{"error":"Error: Plugin path not found: /Users/herbcaudill/.claude/plugins/marketplaces/claude-plugins-official/plugins/code-simplifier\n    at p57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:6240)\n    at d57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:5802)\n    at async file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:14659","timestamp":"2026-01-18T21:15:51.712Z"},{"error":"Error: Plugin path not found: /Users/herbcaudill/.claude/plugins/marketplaces/claude-plugins-official/plugins/frontend-design\n    at p57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:6240)\n    at d57 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:5802)\n    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)\n    at async file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3265:14659","timestamp":"2026-01-18T21:15:51.744Z"},{"error":"MaxFileReadTokenExceededError: File content (93214 tokens) exceeds maximum allowed tokens (25000). Please use offset and limit parameters to read specific portions of the file, or use the GrepTool to search for specific content.\n    at PA2 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1681:13298)\n    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)\n    at async Object.call (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1690:996)\n    at async file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3218:1513","timestamp":"2026-01-18T21:17:10.965Z"},{"error":"MaxFileReadTokenExceededError: File content (66415 tokens) exceeds maximum allowed tokens (25000). Please use offset and limit parameters to read specific portions of the file, or use the GrepTool to search for specific content.\n    at PA2 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1681:13298)\n    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)\n    at async Object.call (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1690:996)\n    at async file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:3218:1513","timestamp":"2026-01-18T21:17:11.417Z"}]