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Sweep 09 Oct 2026 · 17:27Z Build v2.1.296 517 read Stable v2.1.287 Latest v2.1.296 Next v2.1.296 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeDocsClaude Developer Platform 28 Sep 2026
One change · api

reference changedmanaged-agents/reference

Nearest release: v2.1.284, published an hour before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Recorded here
Lines+3added
Lines−3removed
From line 76 where the diff opens
First seen 14 Aug 2026 this site's first read of the page
Recorded edits14to this page, all time

The whole hunk

from line 76, old and new numbered
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from line 76
7676 </Tab>
7777 
7878 <Tab title="System events">
79 | Type | Description |
80 | ---------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
81 | `system.message` | Append privileged system-level context that applies to the accompanying turn and all subsequent turns. Supported on Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, and Claude Opus 4.8. On an unsupported primary model the event is rejected with `model_does_not_support_mid_conversation_system`. |
79 | Type | Description |
80 | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
81 | `system.message` | Append privileged system-level context that applies to the accompanying turn and all subsequent turns. Supported on Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, and Claude Sonnet 5.5. On an unsupported primary model the event is rejected with `model_does_not_support_mid_conversation_system`. |
8282 </Tab>
8383 
8484 <Tab title="Event deltas">
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