Claude Platform release notes

+## Claude Platform release notes — September 22, 2026
+https://platform.claude.com/docs/en/release-notes/overview#september-22-2026
+Tue, 22 Sep 2026 00:00:00 GMT
+
+We've launched Claude Opus 5.5 (claude-opus-5-5), a model for long-running agentic coding and knowledge work. It has a 1M token context window by default, 128k max output tokens, and always-on adaptive thinking, at $4 / $20 USD per MTok (Claude Opus 5 is $5 / $25). Claude Opus 5.5 is available on the Claude API, Claude in Amazon Bedrock, Claude Platform on AWS, Claude on Google Cloud, and Claude in Microsoft Foundry. See What's new in Claude Opus 5.5 for capabilities, API changes, and migration guidance.
+On Claude Opus 5.5, thinking can't be disabled: thinking: {"type": "disabled"} and thinking: {"type": "enabled", ...} return a 400 error. Omit the thinking field and control thinking depth with the effort parameter. tool_choice types any and tool also return a 400 error, as on Claude Fable 5.1; use auto with strict tool use. On the Claude API and Google Cloud, computer use on this model requires the computer_toolset_20260801 toolset and the earlier computer_20251124 tool returns a 400 error; on Amazon Bedrock, computer_20251124 keeps working. See the migration guide.
+Fast mode (research preview) is available for Claude Opus 5.5 on the Claude API.
+Tools can now be defined inside a mid-conversation system message, in beta on the Claude API with the inline-tools-2026-09-15 beta header. A tool_addition block can carry the tool's full definition (tool: {"type": "tool_definition", "definition": {...}}), so you can add a tool, change its schema, or move a server tool to a newer version without editing tools or invalidating the prompt cache. The same header covers adding and removing tools by reference. With the MCP connector's mcp-client-2026-09-15 beta header as well, the definition can be an MCP toolset, and a response records each server's fetched tool list in an mcp_tool_listing block, which pins that list when you send it back.

 https://platform.claude.com/docs/en/release-notes/overview#september-14-2026
 Mon, 14 Sep 2026 00:00:00 GMT
 
-The Messages API can now compact a conversation on demand on the Claude API, in beta with the compact-2026-09-04 beta header. Send the top-level compaction parameter, and the API returns a signed compaction block that summarizes the messages you sent. On later requests, send that block first, in place of those messages. You choose when to compact, the request can run in the background, and you can keep recent turns word for word after the summary. On models with preserved thinking, the thinking in those kept turns can stay valid.
+The Messages API can now compact a conversation on demand on the Claude API, in beta with the compact-2026-09-04 beta header. Send the top-level compaction parameter, and the API returns a signed compaction block that summarizes the messages you sent. On later requests, send that block first, in place of those messages. You choose when to compact, the request can run in the background, and you can keep recent turns word for word after the summary. On models with preserved thinking, the thinking in those kept turns can stay valid.
+With the thinking-binding-controls-2026-08-01 beta header, the input_transformations response field gains a second entry type, thinking_mismatch_allowed. It names a thinking block that failed the prefix check on a request where the API doesn't enforce that check: on Claude Fable 5.1, for example, a request from an account created before August 31, 2026, with prefix_mismatch_behavior unset. The block still reaches the model unchanged. Log these entries to find history edits in production traffic before you opt into enforcement. See Set the mismatch behavior and read input_transformations.

+## Claude Platform release notes — September 14, 2026
+https://platform.claude.com/docs/en/release-notes/overview#september-14-2026
+Mon, 14 Sep 2026 00:00:00 GMT
+
+The Messages API can now compact a conversation on demand on the Claude API, in beta with the compact-2026-09-04 beta header. Send the top-level compaction parameter, and the API returns a signed compaction block that summarizes the messages you sent. On later requests, send that block first, in place of those messages. You choose when to compact, the request can run in the background, and you can keep recent turns word for word after the summary. On models with preserved thinking, the thinking in those kept turns can stay valid.

+## Claude Platform release notes — September 10, 2026
+https://platform.claude.com/docs/en/release-notes/overview#september-10-2026
+Thu, 10 Sep 2026 00:00:00 GMT
+
+Claude Managed Agents permission policies now include auto: the server evaluates each agent or MCP tool call and runs it, denies it, or pauses for your approval. agent.tool_use and agent.mcp_tool_use events report how each call was evaluated in an evaluation field alongside evaluated_permission. See Let the server evaluate each call with auto.
+The ant CLI adds ant beta:sessions connect, which attaches your terminal to a Claude Managed Agents session. You can follow the session live, send messages, and allow or deny tool calls that are waiting for approval. Pass --web to serve the Claude Console's session viewer locally and open the session there instead. See Connect to a Managed Agents session from your terminal.

 https://platform.claude.com/docs/en/release-notes/overview#september-3-2026
 Thu, 03 Sep 2026 00:00:00 GMT
 
-Version 1.30.0 of the ant CLI adds ant apply, which creates and updates agents, environments, skills, memory stores, and deployments from files in your repository. Describe each resource in a file, run ant apply, and approve the plan it prints. Commit the claude-lock.json lockfile it writes so that later runs, on your machine or in CI, update the same resources instead of creating new ones. See Manage resources as code with ant apply.
+Version 1.30.0 of the ant CLI adds ant apply, which creates and updates agents, environments, skills, memory stores, and deployments from files in your repository. Describe each resource in a file, run ant apply, and approve the plan it prints. Commit the claude-lock.json lockfile it writes so that later runs, on your machine or in CI, update the same resources instead of creating new ones. See Manage resources as code with ant apply.
+Per-message effort changes, in beta, are also available on Google Cloud for Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5, with the same mid-conversation-output-config-2026-07-01 beta header.

 Per-message effort changes are in beta on Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5 on the Claude API. Add a role: "system" message with output_config.effort inside messages to change effort for later turns while preserving the prompt cache. Include the mid-conversation-output-config-2026-07-01 beta header in your requests. See Per-message effort.
 Turn-scoped system messages are in beta (mid-conversation-system-clear-at-2026-08-21 header). Set clear_at: "next_user_message" on a mid-conversation role: "system" message and it renders for the current turn only, then stays in the history at no token cost. Per-turn reminders don't accumulate and don't invalidate the prompt cache or later thinking blocks.
 thinking.display accepts a third value, "updates", in beta (thinking-display-updates-2026-08-18 header). Reasoning comes back with an empty thinking field, as under "omitted", and the short progress updates that Claude Fable 5.1, Claude Mythos 5.1, and Claude Fable 5 write between tool calls come back as text, at most one thinking block before a tool call. See Progress updates between tool calls.
-Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's text watermark, and supported image and video files that Claude produces through the code execution tool carry C2PA Content Credentials when you retrieve them through the Files API on the Claude API. Marking requires no changes to your requests or response handling.
+Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's text watermark, and supported image, video, and audio files that Claude produces through the code execution tool carry C2PA Content Credentials when you retrieve them through the Files API on the Claude API. Marking requires no changes to your requests or response handling.
 Like Claude Fable 5, both models require 30-day data retention and aren't available under zero data retention unless expressly authorized by Anthropic. See Model-specific data retention requirements.
 The guides for the Claude Enterprise endpoints of the Admin API (user management and spend limits), the Claude Enterprise Analytics API, and the Compliance API now show the anthropic-version header; send it on every request to these endpoints, as in the rest of the Claude API. See API versions.

 Turn-scoped system messages are in beta (mid-conversation-system-clear-at-2026-08-21 header). Set clear_at: "next_user_message" on a mid-conversation role: "system" message and it renders for the current turn only, then stays in the history at no token cost. Per-turn reminders don't accumulate and don't invalidate the prompt cache or later thinking blocks.
 thinking.display accepts a third value, "updates", in beta (thinking-display-updates-2026-08-18 header). Reasoning comes back with an empty thinking field, as under "omitted", and the short progress updates that Claude Fable 5.1, Claude Mythos 5.1, and Claude Fable 5 write between tool calls come back as text, at most one thinking block before a tool call. See Progress updates between tool calls.
 Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's text watermark, and supported image and video files that Claude produces through the code execution tool carry C2PA Content Credentials when you retrieve them through the Files API on the Claude API. Marking requires no changes to your requests or response handling.
-Like Claude Fable 5, both models require 30-day data retention and aren't available under zero data retention unless expressly authorized by Anthropic. See Model-specific data retention requirements.
+Like Claude Fable 5, both models require 30-day data retention and aren't available under zero data retention unless expressly authorized by Anthropic. See Model-specific data retention requirements.
+The guides for the Claude Enterprise endpoints of the Admin API (user management and spend limits), the Claude Enterprise Analytics API, and the Compliance API now show the anthropic-version header; send it on every request to these endpoints, as in the rest of the Claude API. See API versions.

+## Claude Platform release notes — September 1, 2026
+https://platform.claude.com/docs/en/release-notes/overview#september-1-2026
+Tue, 01 Sep 2026 00:00:00 GMT
+
+We've launched Claude Fable 5.1 (claude-fable-5-1), the successor to Claude Fable 5 for long-running agentic coding, knowledge work, and research, alongside Claude Mythos 5.1 (claude-mythos-5-1) for Project Glasswing participants. Both models support a 1M token context window by default, 128k max output tokens, and always-on adaptive thinking, at $10 / $50 USD per MTok, the same as Claude Fable 5, with cache reads cut to $0.25 per MTok. Claude Fable 5.1 is available on the Claude API, Claude in Amazon Bedrock, Claude Platform on AWS, Claude on Google Cloud, and Claude in Microsoft Foundry. See What's new in Claude Fable 5.1 for capabilities, API changes, and migration guidance.
+Prompt cache reads on Claude Fable 5.1 and Claude Mythos 5.1 cost $0.25 USD per million tokens: 0.025x the base input price, compared with 0.1x on other models. Cache writes are unchanged. See Prompt caching pricing.
+On Claude Fable 5.1 and Claude Mythos 5.1, tool_choice types any and tool aren't supported and return a 400 error. auto and none are unchanged. To guarantee schema-conformant tool inputs, use strict tool use or structured outputs.
+Thinking blocks produced by Claude Fable 5.1 and Claude Mythos 5.1 are preserved only for the model that produced them or a newer one: earlier models can't read them, and the API drops one replayed to an earlier model. Claude Fable 5.1 accepts thinking blocks from Claude Opus 5, Claude Fable 5, Claude Mythos 5, and earlier Claude models. On Claude Fable 5.1, the API also checks that nothing before a block has changed: for new accounts created on or after August 31, 2026, replaying one after the system prompt, tools, or an earlier message changed returns a 400 error. With the thinking-binding-controls-2026-08-01 beta header, dropped blocks are reported in an input_transformations response field, and thinking.block_binding.prefix_mismatch_behavior chooses between rejecting and dropping blocks whose history changed. See Preserved thinking.
+Per-message effort changes are in beta on Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5 on the Claude API. Add a role: "system" message with output_config.effort inside messages to change effort for later turns while preserving the prompt cache. Include the mid-conversation-output-config-2026-07-01 beta header in your requests. See Per-message effort.
+Turn-scoped system messages are in beta (mid-conversation-system-clear-at-2026-08-21 header). Set clear_at: "next_user_message" on a mid-conversation role: "system" message and it renders for the current turn only, then stays in the history at no token cost. Per-turn reminders don't accumulate and don't invalidate the prompt cache or later thinking blocks.
+thinking.display accepts a third value, "updates", in beta (thinking-display-updates-2026-08-18 header). Reasoning comes back with an empty thinking field, as under "omitted", and the short progress updates that Claude Fable 5.1, Claude Mythos 5.1, and Claude Fable 5 write between tool calls come back as text, at most one thinking block before a tool call. See Progress updates between tool calls.
+Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's text watermark, and supported image and video files that Claude produces through the code execution tool carry C2PA Content Credentials when you retrieve them through the Files API on the Claude API. Marking requires no changes to your requests or response handling.
+Like Claude Fable 5, both models require 30-day data retention and aren't available under zero data retention unless expressly authorized by Anthropic. See Model-specific data retention requirements.

+## Claude Platform release notes — August 26, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-26-2026
+Wed, 26 Aug 2026 00:00:00 GMT
+
+The Compliance API session endpoints are out of beta for Cowork and Claude Code sessions. See Retrieve session transcripts.
+The Compliance API local session endpoints now also return transcripts of Claude Science sessions (product_surface value claude_science) and Claude for Microsoft 365 sessions in Excel, PowerPoint, Word, and Outlook (product_surface values beginning with office_agents), in beta for Claude Enterprise organizations, with your existing Compliance Access Key and the read:compliance_user_data scope. See Sessions on users' machines.

 https://platform.claude.com/docs/en/release-notes/overview#august-20-2026
 Thu, 20 Aug 2026 00:00:00 GMT
 
-We've released v1.0 of the Python SDK. The SDK's HTTP layer moves from httpx to httpx2, a maintained, API-compatible fork: build custom http_client, Timeout, and transport objects from httpx2 (the DefaultHttpxClient helpers are unchanged), and call httpx2.alias_httpx() at startup if you rely on tracing or mocking libraries that patch httpx. v1.0 requires Python 3.10 or later and removes long-deprecated surface, including the legacy Text Completions API, the temperature, top_p, and top_k parameters on Messages methods, and the tool runner's client-side compaction_control. On the async client, .with_raw_response results now need await response.parse(), and AnthropicBedrock now raises an error when no AWS region is configured instead of defaulting to us-east-1. See the v1 migration guide for every change with before-and-after snippets.
+We've released v1.0 of the Python SDK. The SDK's HTTP layer moves from httpx to httpx2, a maintained, API-compatible fork: build custom http_client, Timeout, and transport objects from httpx2 (the DefaultHttpxClient helpers are unchanged), and call httpx2.alias_httpx() at startup if you rely on tracing or mocking libraries that patch httpx. v1.0 requires Python 3.10 or later and removes long-deprecated surface, including the legacy Text Completions API, the temperature, top_p, and top_k parameters on Messages methods, and the tool runner's client-side compaction_control. On the async client, .with_raw_response results now need await response.parse(), and AnthropicBedrock now raises an error when no AWS region is configured instead of defaulting to us-east-1. See the v1 migration guide for every change with before-and-after snippets.
+The computer use and browser use toolsets (computer_toolset_20260801 and browser_toolset_20260801) are now available on Google Cloud for Claude Fable 5, Claude Mythos 5, Claude Opus 5, Claude Sonnet 5, and Claude Opus 4.8. Requests use the same tools entries as on the Claude API.

 We've launched the MCP connector in public beta, a feature that allows you to connect to remote MCP servers directly from the Messages API.
 To increase answer quality and decrease tool errors, we've changed the default value for the top_p nucleus sampling parameter in the Messages API from 0.999 to 0.99 for all models. To revert this change, set top_p to 0.999.
 Additionally, when extended thinking is enabled, you can now set top_p to values between 0.95 and 1.
-We've moved our Go SDK from beta to GA.
+Our Go SDK has moved from beta to its first stable release.
 We've included minute and hour level granularity to the Usage page of Console alongside 429 error rates on the Usage page.

+## Claude Platform release notes — August 20, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-20-2026
+Thu, 20 Aug 2026 00:00:00 GMT
+
+We've released v1.0 of the Python SDK. The SDK's HTTP layer moves from httpx to httpx2, a maintained, API-compatible fork: build custom http_client, Timeout, and transport objects from httpx2 (the DefaultHttpxClient helpers are unchanged), and call httpx2.alias_httpx() at startup if you rely on tracing or mocking libraries that patch httpx. v1.0 requires Python 3.10 or later and removes long-deprecated surface, including the legacy Text Completions API, the temperature, top_p, and top_k parameters on Messages methods, and the tool runner's client-side compaction_control. On the async client, .with_raw_response results now need await response.parse(), and AnthropicBedrock now raises an error when no AWS region is configured instead of defaulting to us-east-1. See the v1 migration guide for every change with before-and-after snippets.

 https://platform.claude.com/docs/en/release-notes/overview#august-19th-2024
 Mon, 19 Aug 2024 00:00:00 GMT
 
-We've moved 8,192 token outputs from beta to general availability for Claude Sonnet 3.5.
+8,192-token outputs on Claude Sonnet 3.5 are out of beta and no longer require the max-tokens-3-5-sonnet-2024-07-15 header.

 https://platform.claude.com/docs/en/release-notes/overview#august-19-2026
 Wed, 19 Aug 2026 00:00:00 GMT
 
+The computer use tool is now generally available on the Claude API as the computer_toolset_20260801 toolset: no beta header, batch actions (several actions in one turn), zoom enabled by default, and per-member configuration through configs. Earlier beta versions remain available. Upgrading an existing integration changes the request shape and tool handling; see Migrate from computer_20251124.
+We've launched the browser use tool (browser_toolset_20260801), a client toolset for driving a browser that your application hosts. It works inside a browser viewport rather than a whole desktop, reading the page itself (its accessibility tree, elements, forms, and tabs) and adding element references, form input, tab management, download reporting, and opt-in file upload on top of screenshot-and-click control.
+Both toolsets are available for Claude Fable 5, Claude Mythos 5, Claude Opus 5, Claude Sonnet 5, and Claude Opus 4.8 on the Claude API.
 The Files API is now generally available on the Claude API. Requests to the /v1/files endpoints, and Messages API requests that reference an uploaded file, no longer require the files-api-2025-04-14 beta header. Requests sent without the header use the GA response format: file expiration (set expires_in_seconds when you upload a file; file objects report expires_at), and page and next_page pagination plus an ids[] filter when you list files. /v1/files requests that still send the beta header keep working and return the previous response format.
 Agent Skills and the Skills API (/v1/skills) are now generally available on the Claude API. Requests no longer require the skills-2025-10-02 beta header, including Messages API requests that load Skills through the container parameter. Requests that still send the header continue to work unchanged. See Using Agent Skills with the API.
-The Admin API user-management endpoints for Claude Enterprise (claude.ai) organizations (members, invites, groups, and custom roles) are now generally available. The anthropic-beta: ce-user-management-2026-07-13 header is no longer required on group and custom-role requests; requests that still send it are accepted unchanged. See User management.
+The Admin API user-management endpoints for Claude Enterprise (claude.ai) organizations (members, invites, groups, and custom roles) are now generally available. The anthropic-beta: ce-user-management-2026-07-13 header is no longer required on group and custom-role requests; requests that still send it are accepted unchanged. See User management.
+You can now restrict which sites a Claude Managed Agents agent's web_search and web_fetch tools can reach. Set allowed_domains or blocked_domains on the tool's entry in the agent_toolset_20260401 configs array; web_fetch also accepts max_content_tokens and web_search accepts user_location. Each configs entry is identified by its name and typed by an optional type, and requests that pass only name, enabled, and permission_policy continue to work; in the typed SDKs, configs entries become per-tool types. See Restrict web search and web fetch domains.
+Claude Managed Agents sessions that run in a self-hosted sandbox can now attach memory stores. The Python, TypeScript, and Go SDK workers download each attached store into the sandbox at its mount_path and sync the agent's changes back to the store. See Use memory stores.
+The session viewer in the Claude Console has been redesigned with a timeline minimap, a transcript grouped by model request, and an Inspector panel for session details and cost, raw events, per-tool statistics, mounted resources, and per-thread activity. See Console observability.

+## Claude Platform release notes — August 19, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-19-2026
+Wed, 19 Aug 2026 00:00:00 GMT
+
+The Files API is now generally available on the Claude API. Requests to the /v1/files endpoints, and Messages API requests that reference an uploaded file, no longer require the files-api-2025-04-14 beta header. Requests sent without the header use the GA response format: file expiration (set expires_in_seconds when you upload a file; file objects report expires_at), and page and next_page pagination plus an ids[] filter when you list files. /v1/files requests that still send the beta header keep working and return the previous response format.
+Agent Skills and the Skills API (/v1/skills) are now generally available on the Claude API. Requests no longer require the skills-2025-10-02 beta header, including Messages API requests that load Skills through the container parameter. Requests that still send the header continue to work unchanged. See Using Agent Skills with the API.
+The Admin API user-management endpoints for Claude Enterprise (claude.ai) organizations (members, invites, groups, and custom roles) are now generally available. The anthropic-beta: ce-user-management-2026-07-13 header is no longer required on group and custom-role requests; requests that still send it are accepted unchanged. See User management.

 Tue, 11 Aug 2026 00:00:00 GMT
 
 The Compliance API now returns transcripts of Cowork and Claude Code sessions that run on your users' machines, in beta for Claude Enterprise organizations. GET /v1/compliance/apps/sessions/local lists sessions across your organization, GET /v1/compliance/apps/sessions/local/{session_id} retrieves one session's metadata, and GET /v1/compliance/apps/sessions/local/{session_id}/messages returns its transcript, all with your existing Compliance Access Key and the read:compliance_user_data scope. See Retrieve local sessions.
+We've added the anthropic-workspace-id response header to the Claude API. It carries the wrkspc_-prefixed ID of the workspace that the request's API key or access token resolved to, including your organization's Default Workspace. See Identify the workspace behind an API response.
 
 ## Claude Platform release notes — August 12, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-12-2025

 https://platform.claude.com/docs/en/release-notes/overview#april-14-2026
 Tue, 14 Apr 2026 00:00:00 GMT
 
-We announced the deprecation of the Claude Sonnet 4 model (claude-sonnet-4-20250514) and the Claude Opus 4 model (claude-opus-4-20250514), with retirement on the Claude API scheduled for June 15, 2026. We recommend migrating to Claude Sonnet 4.6 and Claude Opus 4.8 respectively. Read more in model deprecations.
+We announced the deprecation of the Claude Sonnet 4 model (claude-sonnet-4-20250514) and the Claude Opus 4 model (claude-opus-4-20250514), with retirement on the Claude API scheduled for June 15, 2026. We recommend migrating to Claude Sonnet 4.6 and Claude Opus 4.8 respectively. Read more in Model deprecations.
 
 ## Claude Platform release notes — April 16, 2026
 https://platform.claude.com/docs/en/release-notes/overview#april-16-2026
@@
 
 Some customers might encounter 429 (rate_limit_error) errors following a sharp increase in API usage due to acceleration limits on the API. Previously, 529 (overloaded_error) errors would occur in similar scenarios.
 
+## Claude Platform release notes — August 11, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-11-2026
+Tue, 11 Aug 2026 00:00:00 GMT
+
+The Compliance API now returns transcripts of Cowork and Claude Code sessions that run on your users' machines, in beta for Claude Enterprise organizations. GET /v1/compliance/apps/sessions/local lists sessions across your organization, GET /v1/compliance/apps/sessions/local/{session_id} retrieves one session's metadata, and GET /v1/compliance/apps/sessions/local/{session_id}/messages returns its transcript, all with your existing Compliance Access Key and the read:compliance_user_data scope. See Retrieve local sessions.
+
 ## Claude Platform release notes — August 12, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-12-2025
 Tue, 12 Aug 2025 00:00:00 GMT
@@
 Wed, 05 Aug 2026 00:00:00 GMT
 
 Inference hooks are now in beta for Claude Enterprise organizations. Point Claude at your organization's AI security server, and each governed prompt across claude.ai, Cowork, and Claude Code is held for the server's allow or deny verdict before inference proceeds. Requests are signed, failure handling is configurable, and every denial is recorded in the compliance Activity Feed. See Inference hooks.
-We've retired the Claude Opus 4.1 model (claude-opus-4-1-20250805). All requests to this model will now return an error. We recommend upgrading to Claude Opus 5. Researchers can request ongoing access through the External Researcher Access Program.
+We've retired the Claude Opus 4.1 model (claude-opus-4-1-20250805). All requests to this model on the Claude API will now return an error. We recommend upgrading to Claude Opus 5. Researchers can request ongoing access through the External Researcher Access Program.
 
+## Claude Platform release notes — August 7, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-7-2026
+Fri, 07 Aug 2026 00:00:00 GMT
+
+You can now set a budget on a Claude Managed Agents session: a hard cap on the session's spend, priced at public list rates. A session that reaches its budget pauses with the budget_reached stop reason instead of starting new model requests; changing or removing the budget resumes it. Deployments accept the same budget and apply it to each session they start. See Session budgets.
+You can now give a Claude Managed Agents session an advisor: a model at least as capable as the agent's own that the session's primary thread can consult mid-turn for strategic guidance. Configure it as a {"type": "advisor"} entry in the agent's multiagent roster, naming the model to consult. See Give the session an advisor.
+You can now control where model inference runs for a Claude Managed Agents agent. Set inference_geo inside the model object when you create the agent, or override it for a single session. See Data residency for the available geos and pricing.
+Claude Managed Agents sessions can now load skills from a GitHub repository. When a session mounts a repository, any skills in its root .claude/skills directory are discovered automatically at session start and available to the agent for that session.
+
 ## Claude Platform release notes — August 8, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-8-2025
 Fri, 08 Aug 2025 00:00:00 GMT
@@
 Thu, 19 Feb 2026 00:00:00 GMT
 
 We've launched automatic caching for the Messages API. Add a single cache_control field to your request body and the system automatically caches the last cacheable block, moving the cache point forward as conversations grow. No manual breakpoint management required. Works alongside existing block-level cache control for fine-grained optimization. Available on the Claude API and Microsoft Foundry (preview). Learn more in Prompt caching.
-We've retired the Claude Sonnet 3.7 model (claude-3-7-sonnet-20250219) and the Claude Haiku 3.5 model (claude-3-5-haiku-20241022). All requests to these models will now return an error. We recommend upgrading to Claude Sonnet 4.6 and Claude Haiku 4.5 respectively. Researchers can request ongoing access through the External Researcher Access Program.
+We've retired the Claude Sonnet 3.7 model (claude-3-7-sonnet-20250219) and the Claude Haiku 3.5 model (claude-3-5-haiku-20241022). All requests to Claude Sonnet 3.7 will now return an error. Requests to Claude Haiku 3.5 on the Claude API will now return an error; it remains available on Amazon Bedrock and Google Cloud. We recommend upgrading to Claude Sonnet 4.6 and Claude Haiku 4.5 respectively. Researchers can request ongoing access through the External Researcher Access Program.
 We announced the deprecation of the Claude Haiku 3 model (claude-3-haiku-20240307), with retirement scheduled for April 20, 2026. We recommend migrating to Claude Haiku 4.5. Read more in Model deprecations.
 
 ## Claude Platform release notes — February 24th, 2025
@@
 https://platform.claude.com/docs/en/release-notes/overview#june-15-2026
 Mon, 15 Jun 2026 00:00:00 GMT
 
-We've retired the Claude Sonnet 4 model (claude-sonnet-4-20250514) and the Claude Opus 4 model (claude-opus-4-20250514). All requests to these models will now return an error. We recommend upgrading to Claude Sonnet 4.6 and Claude Opus 4.8 respectively. Researchers can request ongoing access through the External Researcher Access Program.
+We've retired the Claude Sonnet 4 model (claude-sonnet-4-20250514) and the Claude Opus 4 model (claude-opus-4-20250514). All requests to these models on the Claude API will now return an error. We recommend upgrading to Claude Sonnet 4.6 and Claude Opus 4.8 respectively. Researchers can request ongoing access through the External Researcher Access Program.
 
 ## Claude Platform release notes — June 18, 2026
 https://platform.claude.com/docs/en/release-notes/overview#june-18-2026
@@
 https://platform.claude.com/docs/en/release-notes/overview#june-5-2026
 Fri, 05 Jun 2026 00:00:00 GMT
 
-We announced the deprecation of the Claude Opus 4.1 model (claude-opus-4-1-20250805), with retirement on the Claude API scheduled for August 5, 2026. We recommend migrating to Claude Opus 4.8. Read more in model deprecations.
+We announced the deprecation of the Claude Opus 4.1 model (claude-opus-4-1-20250805), with retirement on the Claude API scheduled for August 5, 2026. We recommend migrating to Claude Opus 4.8. Read more in Model deprecations.
 
 ## Claude Platform release notes — June 9, 2026
 https://platform.claude.com/docs/en/release-notes/overview#june-9-2026

 
 Dreams (research preview) now supports Claude Opus 5. See Supported models.
 
+## Claude Platform release notes — August 10, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-10-2026
+Mon, 10 Aug 2026 00:00:00 GMT
+
+The introductory pricing for Claude Sonnet 5 ($2 / $10 per MTok) is now the standard price: the previously scheduled increase to $3 / $15 per MTok on September 1, 2026 will not occur. See Pricing.
+
 ## Claude Platform release notes — August 11, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-11-2025
 Mon, 11 Aug 2025 00:00:00 GMT
@@
 
 We launched a beta version of the PHP SDK.
 
+## Claude Platform release notes — August 3, 2026
+https://platform.claude.com/docs/en/release-notes/overview#august-3-2026
+Mon, 03 Aug 2026 00:00:00 GMT
+
+The Compliance API now returns transcripts of Cowork sessions started on claude.ai web or mobile, in beta for Claude Enterprise organizations. GET /v1/compliance/apps/sessions/remote lists sessions and GET /v1/compliance/apps/sessions/remote/{session_id}/messages returns one session's transcript, using your existing Compliance Access Key with the read:compliance_user_data scope. See Retrieve remote sessions.
+
 ## Claude Platform release notes — August 5, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-5-2025
 Tue, 05 Aug 2025 00:00:00 GMT
@@
 Wed, 05 Aug 2026 00:00:00 GMT
 
 Inference hooks are now in beta for Claude Enterprise organizations. Point Claude at your organization's AI security server, and each governed prompt across claude.ai, Cowork, and Claude Code is held for the server's allow or deny verdict before inference proceeds. Requests are signed, failure handling is configurable, and every denial is recorded in the compliance Activity Feed. See Inference hooks.
+We've retired the Claude Opus 4.1 model (claude-opus-4-1-20250805). All requests to this model will now return an error. We recommend upgrading to Claude Opus 5. Researchers can request ongoing access through the External Researcher Access Program.
 
 ## Claude Platform release notes — August 8, 2025
 https://platform.claude.com/docs/en/release-notes/overview#august-8-2025
@@
 https://platform.claude.com/docs/en/release-notes/overview#june-30-2026
 Tue, 30 Jun 2026 00:00:00 GMT
 
-We've launched Claude Sonnet 5 (claude-sonnet-5), the next generation of our Sonnet model family, at introductory pricing of $2 / $10 per MTok through August 31, 2026 (standard $3 / $15 thereafter). Claude Sonnet 5 supports a 1M token context window, 128k max output tokens, and the same set of tools and platform features as Claude Sonnet 4.6, except Priority Tier, which is not available on Claude Sonnet 5. Three behavior changes apply when migrating: adaptive thinking is now on by default; manual extended thinking (thinking: {type: "enabled", budget_tokens: N}) is removed and returns a 400 error (it was deprecated on Sonnet 4.6); and setting sampling parameters (temperature, top_p, top_k) to non-default values returns a 400 error. Claude Sonnet 5 also uses a new tokenizer that produces approximately 30% more tokens for the same text. The exact increase depends on the content and workload shape. See What's new in Claude Sonnet 5 for details and migration guidance. For behavioral differences and model-specific prompting patterns, see Prompting Claude Sonnet 5.
+We've launched Claude Sonnet 5 (claude-sonnet-5), the next generation of our Sonnet model family, at introductory pricing of $2 / $10 per MTok (made the standard price on August 10, 2026). Claude Sonnet 5 supports a 1M token context window, 128k max output tokens, and the same set of tools and platform features as Claude Sonnet 4.6, except Priority Tier, which is not available on Claude Sonnet 5. Three behavior changes apply when migrating: adaptive thinking is now on by default; manual extended thinking (thinking: {type: "enabled", budget_tokens: N}) is removed and returns a 400 error (it was deprecated on Sonnet 4.6); and setting sampling parameters (temperature, top_p, top_k) to non-default values returns a 400 error. Claude Sonnet 5 also uses a new tokenizer that produces approximately 30% more tokens for the same text. The exact increase depends on the content and workload shape. See What's new in Claude Sonnet 5 for details and migration guidance. For behavioral differences and model-specific prompting patterns, see Prompting Claude Sonnet 5.
 Claude Managed Agents session event streams now support event deltas. Opt in with the event_deltas[] query parameter on GET /v1/sessions/{session_id}/events/stream. The event_start and event_delta events preview an agent message's text as it's generated, before the complete agent.message event arrives.
 Listing sessions for Claude Managed Agents now supports backward pagination. GET /v1/sessions returns a prev_page cursor alongside next_page; pass it as the page parameter to return to the previous page. See Pagination.
 When creating a Claude Managed Agents session, you can now override the agent's configuration for that session. Pass agent with type: "agent_with_overrides" to replace the model, system prompt, tools, MCP servers, or skills for a single session. The agent itself is unchanged.