overview changedrelease-notes/overview
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1919### October 7, 2026
2020
2121* We've lowered the price of prompt cache reads on Claude Sonnet 5.5 from $0.20 USD to $0.10 USD per million tokens: 0.05x the base input price instead of 0.1x. Cache writes and all other prices are unchanged. See [Prompt caching pricing](https://platform.claude.com/docs/en/about-claude/pricing#prompt-caching).
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23### October 7, 2026
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2522* We've launched **Claude Haiku 5.5** (`claude-haiku-5-5`), our most capable model tuned for high-volume and latency-sensitive work. It has a [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows), 128k max output tokens, and [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) with the [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort). It's available on the Claude API, [Claude in Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude on Google Cloud](https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai), and [Claude in Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry). See [What's new in Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/whats-new-haiku-5-5).
2623* Code written for Claude Haiku 4.5 can break on Claude Haiku 5.5. Manual extended thinking (`budget_tokens`) returns a 400 error, and adaptive thinking is on by default, so a response can begin with `thinking` blocks. The same text also counts as more tokens. See the [migration guide](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide). For model-specific prompting patterns, see [Prompting Claude Haiku 5.5](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-haiku-5-5).
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28### October 7, 2026
29
3024* The Python and TypeScript SDKs now include classes, in beta, for the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) and the [computer use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool). You subclass one and write one method per tool against your own browser or desktop automation. The SDK runs the tool loop, the URL and file policies you set for the browser, and your approval callback. See [Browser and computer use with the SDK toolsets](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-sdk).
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32### October 7, 2026
33
3425* Claude Max and Team plans now include monthly API credits. To learn how to claim them, see [API credits for Max and Team plans](https://platform.claude.com/docs/en/about-claude/api-credits-for-subscribers).
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36### October 7, 2026
37
3826* In Claude Managed Agents, a cloud environment with `limited` networking now also applies its `allowed_hosts` to the `web_search` and `web_fetch` tools. A `web_fetch` call for a URL on a host that `allowed_hosts` does not match returns a `url_not_allowed` error result to the agent. `web_search` omits results from such hosts. When `allowed_hosts` lists no hosts, neither tool returns a page or a search result. `allow_package_managers` and `allow_mcp_servers` add no hosts for these tools. To let the tools reach a host, add it to `allowed_hosts`, which also opens it to the sandbox. `unrestricted` networking and self-hosted environments do not limit these tools. See [Environment networking](https://platform.claude.com/docs/en/managed-agents/environments#networking).
3927* With `limited` networking, creating a session fails with a 400 error when an enabled web tool's `allowed_domains` has an entry not within `allowed_hosts`. So does a session update that adds such an entry. An `allowed_hosts` entry matches one exact host unless it starts with `*.`, so `docs.example.com` is not within `["example.com"]`. To fix the error, add the host to `allowed_hosts` or remove the entry from `allowed_domains`. See [Restrict web search and web fetch domains](https://platform.claude.com/docs/en/managed-agents/tools-web-restrictions).
28* In Claude Managed Agents, the [`web_fetch` tool](https://platform.claude.com/docs/en/managed-agents/tools#available-tools) now fetches only URLs that have already appeared in the session, for example in the text of a user message, in a `web_search` result, or in a page that `web_fetch` returned earlier. This reduces the risk of data exfiltration. A URL that appears only in Claude's own output, the agent's system prompt, an attached document, or the output of a tool such as `bash`, `read`, or an MCP tool does not count: a `web_fetch` call for it returns a `url_not_in_prior_context` error result to the agent. To let the agent fetch a URL, send it in the text of a `user.message` event.
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4130### October 6, 2026
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4938### October 1, 2026
5039
5140* We've added a `line` field to the [Models API](https://platform.claude.com/docs/en/api/models/list). `GET /v1/models` and `GET /v1/models/{model_id}` now return the model line each model belongs to. Claude Opus 4.5 and Claude Opus 4.6 both report `opus`, for example. Use `line` to group models without parsing their IDs. `line` is `null` for a model that belongs to no line. See [Using the Models API](https://platform.claude.com/docs/en/models/overview#using-the-models-api).
41* [Dreams](https://platform.claude.com/docs/en/managed-agents/dreams) (research preview) now supports Claude Opus 5.5, Claude Fable 5.1, and Claude Sonnet 5.5. See [Supported models](https://platform.claude.com/docs/en/managed-agents/dreams#limits).
5242
5343### September 30, 2026
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142132* The [Admin API](https://platform.claude.com/docs/en/api/beta/organization) user-management endpoints for **Claude Enterprise** (claude.ai) organizations (members, invites, groups, and custom roles) are out of beta. 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](https://platform.claude.com/docs/en/manage-claude/user-management).
143133* 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](https://platform.claude.com/docs/en/managed-agents/tools#config-entry-types-in-the-sdks). See [Restrict web search and web fetch domains](https://platform.claude.com/docs/en/managed-agents/tools-web-restrictions).
144134* Claude Managed Agents sessions that run in a [self-hosted sandbox](https://platform.claude.com/docs/en/managed-agents/self-hosted-sandboxes) can now attach [memory stores](https://platform.claude.com/docs/en/managed-agents/memory). 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 [Memory stores in self-hosted sandboxes](https://platform.claude.com/docs/en/managed-agents/self-hosted-sandboxes-memory).
145* 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](https://platform.claude.com/docs/en/managed-agents/events-and-streaming#console-observability).
135* 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 [Inspect a session in the Console](https://platform.claude.com/docs/en/managed-agents/session-observability#inspect-a-session-in-the-console).
146136
147137### August 18, 2026
148138
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192182* Webhooks for Claude Managed Agents now cover the environment and memory store lifecycle: four `environment.*` event types and three `memory_store.*` event types. You can react to environment and memory store lifecycle changes without polling. See the Environment events and Memory store events tabs in [Subscribe to webhooks](https://platform.claude.com/docs/en/managed-agents/webhooks#supported-event-types).
193183* When creating a Claude Managed Agents session, you can now [seed it with initial events](https://platform.claude.com/docs/en/managed-agents/sessions#seed-the-session-with-initial-events). Pass `initial_events` on `POST /v1/sessions` with up to 50 `user.message` and `user.define_outcome` events. A non-empty list starts the agent loop in the same call, so you don't need a separate send-events request to start work.
194184* The `version` field is now optional when [updating a Claude Managed Agents agent](https://platform.claude.com/docs/en/managed-agents/agent-setup#update-an-agent). Supply it for optimistic concurrency (a mismatch returns a 409 error), or omit it to apply the update unconditionally. See [Update semantics](https://platform.claude.com/docs/en/managed-agents/agent-setup#update-semantics).
195* Claude Managed Agents session thread event streams now support [event deltas](https://platform.claude.com/docs/en/managed-agents/events-and-streaming#event-deltas). `GET /v1/sessions/{session_id}/threads/{thread_id}/stream` accepts the same `event_deltas[]` query parameter as the session-level stream, so you can preview a subagent's text as the model generates it. A connection previews only the thread it's reading. See [Preview session thread events](https://platform.claude.com/docs/en/managed-agents/events-and-streaming#preview-session-thread-events).
185* Claude Managed Agents session thread event streams now support [event deltas](https://platform.claude.com/docs/en/managed-agents/event-deltas). `GET /v1/sessions/{session_id}/threads/{thread_id}/stream` accepts the same `event_deltas[]` query parameter as the session-level stream, so you can preview a subagent's text as the model generates it. A connection previews only the thread it's reading. See [Preview session thread events](https://platform.claude.com/docs/en/managed-agents/event-deltas#preview-session-thread-events).
196186
197187### July 17, 2026
198188
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228218### June 30, 2026
229219
230220* 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](https://platform.claude.com/docs/en/build-with-claude/context-windows), 128k max output tokens, and the same set of tools and platform features as Claude Sonnet 4.6, except [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models), which is not available on Claude Sonnet 5. Three behavior changes apply when migrating: [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/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](https://platform.claude.com/docs/en/models/sonnet-5/overview) for details and migration guidance. For behavioral differences and model-specific prompting patterns, see [Prompting Claude Sonnet 5](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-sonnet-5).
231* Claude Managed Agents session event streams now support [event deltas](https://platform.claude.com/docs/en/managed-agents/events-and-streaming#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.
221* Claude Managed Agents session event streams now support [event deltas](https://platform.claude.com/docs/en/managed-agents/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.
232222* [Listing sessions](https://platform.claude.com/docs/en/managed-agents/session-operations#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](https://platform.claude.com/docs/en/api/overview#pagination).
233223* When creating a Claude Managed Agents session, you can now [override the agent's configuration for that session](https://platform.claude.com/docs/en/managed-agents/sessions#override-agent-configuration-for-a-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.
234224* Claude Managed Agents vaults now support an `injection_location` setting on [environment variable credentials](https://platform.claude.com/docs/en/managed-agents/vaults#add-a-credential) (the Environment variable tab). It controls whether the credential's value is substituted, at egress, into the agent's outbound request headers, the request body, or both.
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