[Bug] Extended thinking mode causes API timeout and hangs CLI startup

Bug Description
Bug Report:

Claude Code v2.0.64 - OAuth authentication broken

Environment:

Claude Code v2.0.64
Linux (Ubuntu)
Max subscription (confirmed in credentials)

Symptom: Claude Code hangs on "Coalescing..." at startup. Any command including claude auth status hangs indefinitely.

Root cause: API is rejecting valid OAuth tokens with explicit error message.

Reproduction: Logged out and back in, constant time-outs. Logged in fine via curl via API key. API login also rejected in Claude Code. Final resolution turned out to be: I switched from "alwaysThinkingEnabled": true --> to false and that resolved the problem.

Environment Info

• Platform: linux
• Terminal: konsole
• Version: 2.0.64
• Feedback ID: 142d1afa-2d62-43bf-94ac-a3dafe0a5572

Errors

[{"error":"Error: Could not resolve authentication method. Expected either apiKey or authToken to be set. Or for one of the \"X-Api-Key\" or \"Authorization\" headers to be explicitly omitted\n    at BR.validateHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:1008)\n    at BR.buildHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:8501)\n    at async BR.buildRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:7559)\n    at async BR.makeRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:3387)\n    at async Lb2.C11.model (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:11055)\n    at async C11 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1925:3271)\n    at async Lb2 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:11209)\n    at async file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:3864\n    at async _g1 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1295:2037)\n    at async P7A (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:3834)","timestamp":"2025-12-10T19:53:48.633Z"},{"error":"Error: Could not resolve authentication method. Expected either apiKey or authToken to be set. Or for one of the \"X-Api-Key\" or \"Authorization\" headers to be explicitly omitted\n    at BR.validateHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:1008)\n    at BR.buildHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:8501)\n    at async BR.buildRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:7559)\n    at async BR.makeRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:3387)\n    at async Lb2.C11.model (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:11055)\n    at async C11 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1925:3271)\n    at async Lb2 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:11209)\n    at async file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:3864\n    at async _g1 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1295:2037)\n    at async P7A (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:4021:3834)","timestamp":"2025-12-10T19:53:48.634Z"},{"error":"Error: Could not resolve authentication method. Expected either apiKey or authToken to be set. Or for one of the \"X-Api-Key\" or \"Authorization\" headers to be explicitly omitted\n    at BR.validateHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:1008)\n    at BR.buildHeaders (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:8501)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async BR.buildRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:7559)\n    at async BR.makeRequest (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1145:3387)\n    at async file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1295:2830\n    at async file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1295:2262\n    at async AU3 (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1294:16943)\n    at async jXB (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:1295:2195)\n    at async TqA (file:///home/cy/.npm-global/lib/node_modules/@anthropic-ai/claude-code/cli.js:2079:52)","timestamp":"2025-12-10T

Note: Error logs were truncated.