[Bug] Anthropic API Error: Cannot Modify Thinking Blocks in Assistant Messages

Bug Description
' ⎿  API Error: 400 messages.13.content.10: thinking or redacted_thinking blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.
' randomly appeared

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.152
• Feedback ID: aae619f6-187d-411b-b278-bb514468b9f6

Errors

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.13.content.10: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.\"},\"request_id\":\"req_011CbWVYkbL4btifhtZSqbtr\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63975)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T07:49:10.580Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.13.content.10: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.\"},\"request_id\":\"req_011CbWXqQAi6L8RgLcKuLZug\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63975)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T08:19:10.067Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.13.content.10: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.\"},\"request_id\":\"req_011CbWXsFQAnrhin7QGttALb\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63975)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T08:19:35.132Z"}]