Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
One change · api

Create Session changed

api/beta/sessions/create

Nearest release: v2.1.258, published an hour 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.

Recorded here
Lines+21added
Lines−7removed
From line 12 where the diff opens
First seen 14 Aug 2026 this site's first read of the page
Recorded edits9to this page, all time

The whole hunk

from line 12, old and new numbered
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from line 12
1212 
1313 - `string`
1414 
15 - `"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 38 more`
15 - `"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 41 more`
1616 
1717 - `"message-batches-2024-09-24"`
1818 
from line 96
9696 
9797 - `"ce-user-management-2026-07-13"`
9898 
99 - `"mid-conversation-output-config-2026-07-01"`
100 
101 - `"thinking-binding-controls-2026-08-01"`
102 
103 - `"mid-conversation-system-clear-at-2026-08-21"`
104 
99105## Body parameters
100106 
101107- `agent: string or BetaManagedAgentsAgentParams or BetaManagedAgentsAgentWithOverridesParams`
from line 162
156162 
157163 Replacement model. Accepts the model string, e.g. `claude-opus-5`, or a `model_config` object. Omit to use the agent's model.
158164 
159 - `BetaManagedAgentsModel = "claude-sonnet-5" or "claude-fable-5" or "claude-opus-5" or 10 more or string`
165 - `BetaManagedAgentsModel = "claude-fable-5-1" or "claude-sonnet-5" or "claude-fable-5" or 11 more or string`
160166 
161167 The model that will power your agent.
162168 
163169 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
164170 
165 - `"claude-sonnet-5" or "claude-fable-5" or "claude-opus-5" or 10 more`
171 - `"claude-fable-5-1" or "claude-sonnet-5" or "claude-fable-5" or 11 more`
166172 
167173 The model that will power your agent.
168174 
169175 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
170176 
177 - `"claude-fable-5-1"`
178 
179 Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows
180 
171181 - `"claude-sonnet-5"`
172182 
173183 High-performance model for coding and agents
from line 1106
10961106 
10971107 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
10981108 
1099 - `"claude-sonnet-5" or "claude-fable-5" or "claude-opus-5" or 10 more`
1109 - `"claude-fable-5-1" or "claude-sonnet-5" or "claude-fable-5" or 11 more`
11001110 
11011111 The model that will power your agent.
11021112 
11031113 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
11041114 
1115 - `"claude-fable-5-1"`
1116 
1117 Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows
1118 
11051119 - `"claude-sonnet-5"`
11061120 
11071121 High-performance model for coding and agents
from line 1664
16501664 
16511665 - `outcome_evaluations: array of BetaManagedAgentsOutcomeEvaluationResource`
16521666 
1653 Per-outcome evaluation state. One entry per define_outcome event sent to the session.
1667 Per-outcome evaluation state. One entry per `define_outcome` event sent to the session.
16541668 
16551669 - `completed_at: string or null`
16561670 
from line 1678
16641678 
16651679 - `explanation: string or null`
16661680 
1667 Grader's verdict text from the most recent evaluation. For satisfied, explains why criteria are met; for needs_revision (intermediate), what's missing; for failed, why unrecoverable.
1681 Grader's verdict text from the most recent evaluation. For `satisfied`, explains why criteria are met; for `needs_revision` (intermediate), what's missing; for `failed`, why unrecoverable.
16681682 
16691683 - `iteration: number`
16701684 
from line 1806
17921806 
17931807 - `active_seconds: optional number`
17941808 
1795 Cumulative time in seconds the session spent in running status. Excludes idle time.
1809 Cumulative time in seconds the session spent in `running` status. Excludes idle time.
17961810 
17971811 format: double
17981812