[Bug] Anthropic API Error: Cannot modify thinking blocks in assistant messages

Bug Description
API Error: 400 messages.1.content.14: thinking or redacted_thinking blocks
in the latest assistant message cannot be modified. These blocks must remain as
they were in the original response.

Environment Info

• Platform: darwin
• Terminal: zed
• Version: 2.1.154
• Feedback ID: c0dfb124-312d-4fe4-b5bc-86b5c061adb6

Errors

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.1.content.14: `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_011CbW7MpTsoVsoYELnWBDL9\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63816)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T02:58:12.120Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.1.content.14: `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_011CbW7NSoAXkWgvLwV3Rn7i\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63816)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T02:58:20.713Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.1.content.14: `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_011CbW7PcoDA7pZFSYBX97ev\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63816)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-29T02:58:36.533Z"}]