preserved-thinking changedbuild-with-claude/preserved-thinking
Nearest release: v2.1.310, published 11 hours after this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
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where the diff opens
First seen
1 Sep 2026
this site's first read of the page
Recorded edits35to this page, all time
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5454With the `thinking-binding-controls-2026-08-01` [beta header](https://platform.claude.com/docs/en/api/beta-headers), the response lists each dropped block in a top-level `input_transformations` array with `reason: "model_binding_mismatch"`:
5555
56```text wrap
56```json
5757{
5858 "input_transformations": [
5959 {
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717717Log `input_transformations` on every turn of your own integration. When the API drops a block, the entry looks like the following:
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719```text wrap
719```json
720720{
721721 "input_transformations": [
722722 {
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747747On an older account, you can also watch production traffic without opting into enforcement: send the beta header, leave `block_binding` out, and log `input_transformations`. Sending the header alone doesn't change what the model receives. Every thinking block that comes after the content you edited fails the check and gets its own `thinking_mismatch_allowed` entry, with the same `path` and `reason` fields as a `thinking_dropped` entry. Blocks before the edit still pass. An edit to `system` or `tools` comes before every block, so it fails every thinking block in the request. One entry looks like this:
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749```text wrap
749```json
750750{
751751 "input_transformations": [
752752 {
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14761476The response carries the new assistant turn as usual, plus one `input_transformations` entry for each dropped block. For the history in the diagram, that's the thinking on assistant turns 3 and 4:
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1478```text wrap
1478```json
14791479{
14801480 "input_transformations": [
14811481 {
No line in this hunk matches that.