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Sweep 03 Nov 2026 · 22:27Z Build v2.1.318 536 read Stable v2.1.311 Latest v2.1.318 Next v2.1.318 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeDocsClaude Developer Platform 4 Nov 2026
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cache-diagnostics changedbuild-with-claude/cache-diagnostics

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4343 
4444## Basic usage
4545 
46Include the `diagnostics` object on every turn. The object is the opt-in: the API stores a fingerprint only for requests that include it. On the first turn, pass `"previous_message_id": null` to opt in without a prior message to compare against. On subsequent turns, pass the `id` from the previous response. The `cache-diagnosis-2026-04-07` beta header is no longer required, and requests that still send it work as before.
46Include the `diagnostics` object on every turn. The object is the opt-in: the API stores a fingerprint only for requests that include it. On the first turn, pass `"previous_message_id": null` to opt in without a prior message to compare against. On subsequent turns, pass the `id` from the previous response. The `cache-diagnosis-2026-04-07` beta header is no longer required, and requests that send it work as before.
4747 
4848<CodeGroup>
4949 ```bash cURL
from line 50
5050 # Turn 1: establish the cache and opt in to diagnostics
5151 curl -sS --fail-with-body https://api.anthropic.com/v1/messages \
5252 -H "x-api-key: $ANTHROPIC_API_KEY" \
53 -H "anthropic-version: 2023-06-01" \
53 -H "anthropic-version: 2026-10-21" \
5454 -H "content-type: application/json" \
5555 -d '{
5656 "model": "claude-opus-5-5",
from line 65
6565 # In the response, diagnostics: null means no divergence was found.
6666 curl -sS --fail-with-body https://api.anthropic.com/v1/messages \
6767 -H "x-api-key: $ANTHROPIC_API_KEY" \
68 -H "anthropic-version: 2023-06-01" \
68 -H "anthropic-version: 2026-10-21" \
6969 -H "content-type: application/json" \
7070 -d '{
7171 "model": "claude-opus-5-5",
from line 414
414414 # a null value means no divergence was found.
415415 curl -sS --fail-with-body https://api.anthropic.com/v1/messages \
416416 -H "x-api-key: $ANTHROPIC_API_KEY" \
417 -H "anthropic-version: 2023-06-01" \
417 -H "anthropic-version: 2026-10-21" \
418418 -H "content-type: application/json" \
419419 -d '{
420420 "model": "claude-opus-5-5",
from line 1035
10351035 
10361036## Limitations
10371037 
1038* **Claude API only:** Not available on Amazon Bedrock or Claude Models on Google Cloud (Google managed).
1038* **Claude API only:** Not available on Claude Models on Google Cloud (Google managed) or Amazon Bedrock.
10391039* **Limited retention:** Fingerprints for `previous_message_id` lookup expire after a short period. Run diagnostic comparisons between closely spaced requests.
10401040* **Same workspace:** The previous request must have run in the same organization and workspace. To check, compare the `anthropic-workspace-id` [response header](https://platform.claude.com/docs/en/api/overview#response-headers) on the two responses.
10411041* **Comparison horizon:** For very long conversations where the only change is deep in the message list, the response might be `unavailable` rather than a precise location.
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