# Anthropic Claude Platform release notes — API-surface digest (2025 → 2026-09-18)

**Status:** `DOCUMENTED` (digest of the official release notes; newest first as in the source, grouped by month).  
**Sources:** https://platform.claude.com/docs/en/release-notes/overview (same content as release-notes/api; retrieved 2026-09-18). Model launch dates cross-checked against `GET /v1/models` `created_at` (see docs/models/anthropic-models.md §2 for the small offsets).  
**Last verified:** 2026-09-18.

Focus: changes to the API surface (endpoints, parameters, headers, tools, models, limits, pricing). Console-only and Claude-apps items are omitted or one-lined. **Bold** = model launch/retirement.

## 2026

### September
- **09-18** Compliance API local sessions also return Claude in Chrome transcripts (`product_surface: claude_in_chrome`, beta).
- **09-14** Compact on demand: top-level `compaction` param → signed `compaction` block (beta `compact-2026-09-04`).
- **09-10** Managed Agents permission policy `auto` (server evaluates each tool call; `evaluation` field on `agent.tool_use` events); `ant` CLI 1.32 `ant beta:sessions connect`.
- **09-03** `ant apply` (resources as code, `claude-lock.json`); per-message effort beta also on Google Cloud (Fable 5.1, Mythos 5.1, Opus 5).
- **09-01 — Claude Fable 5.1 (`claude-fable-5-1`) and Claude Mythos 5.1 (`claude-mythos-5-1`, Glasswing)**: 1M context default, 128k output, always-on adaptive thinking, $10/$50, cache reads $0.25 (0.025x). `tool_choice` `any`/`tool` → 400 on these models. Thinking blocks bound to producing model (older models can't read them); prefix check on replay (400 for accounts created ≥ 2026-08-31); beta `thinking-binding-controls-2026-08-01` adds `input_transformations` + `thinking.block_binding.prefix_mismatch_behavior`. Per-message effort beta (`mid-conversation-output-config-2026-07-01`). Turn-scoped system messages beta (`mid-conversation-system-clear-at-2026-08-21`, `clear_at: next_user_message`). `thinking.display: "updates"` beta (`thinking-display-updates-2026-08-18`). Text watermark + C2PA credentials on code-execution media via Files API. 30-day retention required. Admin/Analytics/Compliance docs now show `anthropic-version` — send it everywhere.

### August
- **08-27** SDKs (Py 1.2.0, TS 0.122.0, Go 1.68.0, Java 2.59.0, Ruby 1.67.0, C# 12.44.0): `client.beta.files` / `client.beta.skills` stop sending `files-api-2025-04-14` / `skills-2025-10-02`; `BetaSkill` → `BetaContainerSkill`; `beta.skills.delete` deletes all versions. Console: personal keys and service-account keys (workspace keys legacy).
- **08-26** Compliance API session endpoints GA for Cowork/Claude Code; Claude Science and Microsoft 365 surfaces (beta). Admin API in CLI + all SDKs under `client.beta.organization` (usage/cost reports and CE endpoints stay curl-only).
- **08-20** **Python SDK v1.0**: httpx → httpx2; Python ≥ 3.10; removes Text Completions API, `temperature`/`top_p`/`top_k` on Messages, tool runner `compaction_control`; async `.with_raw_response` needs `await response.parse()`; `AnthropicBedrock` errors without region. Computer/browser toolsets on Google Cloud (Fable 5, Mythos 5, Opus 5, Sonnet 5, Opus 4.8).
- **08-19** **Computer use GA** as `computer_toolset_20260801` (no header, batch actions, `zoom` default, `configs`); **browser use tool** `browser_toolset_20260801` launched; both for Fable 5, Mythos 5, Opus 5, Sonnet 5, Opus 4.8. **Files API GA** (`expires_in_seconds`/`expires_at`, `page`/`next_page`, `ids[]`; header → old shape). **Agent Skills / `/v1/skills` GA**. Admin API CE user management GA (`ce-user-management-2026-07-13` optional). Managed Agents `web_search`/`web_fetch` domain allow/block lists in `agent_toolset_20260401` `configs`; memory stores in self-hosted sandboxes.
- **08-18** Workbench → **playground**.
- **08-11** Compliance API local sessions (`GET /v1/compliance/apps/sessions/local…`, beta). New response header **`anthropic-workspace-id`**.
- **08-10** Sonnet 5 introductory $2/$10 made permanent.
- **08-07** Managed Agents: session budgets (`budget_reached` stop), advisor entry in multiagent roster, `model.inference_geo`, skills from GitHub `.claude/skills`.
- **08-05** Inference hooks (CE, beta). **Claude Opus 4.1 retired** (`claude-opus-4-1-20250805`).
- **08-03** Compliance API remote Cowork sessions (beta). **08-01** Dreams supports Opus 5.

### July
- **07-24 — Claude Opus 5 (`claude-opus-5`)**: 1M context (default and max), 128k output, thinking on by default, $5/$25. Breaking: `thinking: disabled` only at effort ≤ `high` (400 at `xhigh`/`max`). Full effort ladder incl. `max`. Mid-conversation tool changes beta (`mid-conversation-tool-changes-2026-07-01`) on Fable 5, Mythos 5, Opus 4.8, Opus 5. `fallbacks` `"default"` mode (`server-side-fallback-2026-07-01`). **Fast mode removed for Opus 4.7** (error).
- **07-22** Managed Agents: `model.effort`; environment/memory-store webhooks; `initial_events` on `POST /v1/sessions`; optional `version` on agent update (409 on mismatch); thread-level `event_deltas[]`.
- **07-17** Legacy Workbench and `/v1/experimental/{generate,improve,templatize}_prompt` retire 2026-08-17.
- **07-15** Mid-conversation system messages available on Fable 5, Mythos 5, Opus 4.8 (API, Bedrock, Vertex; no header).
- **07-14** Admin API CE user management beta (`ce-user-management-2026-07-13` for groups/roles).
- **07-10** Dreams supports Fable 5 and Sonnet 5. **07-08** API-key expiration (`expires_at` in Admin API).
- **07-02** `agent-memory-2026-07-22` header (memory list semantics; replaces `managed-agents-2026-04-01` on `/v1/memory_stores`; both → 400); SDKs send it by default.
- **07-01** Access to Fable 5 / Mythos 5 restored.

### June
- **06-30 — Claude Sonnet 5 (`claude-sonnet-5`)**: $2/$10 intro, 1M context, 128k output, same tools as Sonnet 4.6 minus Priority Tier; adaptive thinking on by default; manual `enabled` thinking → 400; non-default sampling params → 400; new tokenizer (~+30% tokens). Managed Agents: `event_deltas[]` on session stream, `prev_page` on `GET /v1/sessions`, `agent_with_overrides`, vault `injection_location`, agent/deployment webhooks.
- **06-29** **Fast mode removed for Opus 4.6** (silently standard; `usage.speed`).
- **06-26** **Rate limits raised; tiers consolidated to Start/Build/Scale**; Sonnet/Haiku = Opus limits.
- **06-25** Fast mode on Opus 4.7 deprecated (removal 07-24). **06-22** MCP tunnels API moved to `/v1/tunnels` (`mcp-tunnels-2026-06-22`, `workspace:manage_tunnels`).
- **06-18** SDK support for `code_execution_20260120` (REPL persistence; minimum for programmatic tool calling).
- **06-15** **Sonnet 4 and Opus 4 retired.** **06-11** `code_execution_20260521` (90-s per-cell limit disclosed); `web_search_20260318` / `web_fetch_20260318` add `response_inclusion`.
- **06-10** `GET /v1/environments/{id}/work` on Claude Platform on AWS.
- **06-09 — Claude Fable 5 (`claude-fable-5`) and Claude Mythos 5 (`claude-mythos-5`)**: 1M default, 128k, always-on adaptive thinking (no `disabled`, no budgets, no prefill → 400); new tokenizer; safety classifiers → `stop_reason: "refusal"` (unbilled if no output); opt-in `fallbacks` (beta, not on Batches); `stop_details.category` adds `reasoning_extraction`; `thinking.display` defaults to `omitted`; 30-day retention. Managed Agents scheduled deployments; vault env-var credentials; Compliance Activity Feed on Claude Platform on AWS; `session_thread_id` in webhooks; Swift package for Apple Foundation Models (beta). **Mythos Preview deprecated** (same day).
- **06-05** Opus 4.1 deprecation announced (retire 08-05). **06-02** Advisor tool `max_tokens`; **refusals with no output are no longer billed**.

### May
- **05-29** Managed Agents webhooks/multiagent/self-hosted sandboxes on Claude Platform on AWS.
- **05-28 — Claude Opus 4.8 (`claude-opus-4-8`)**: 1M default (API, Bedrock, Vertex, Foundry), 128k, same tools as 4.7. **Mid-conversation system messages** launched (`role: "system"` in `messages`, no header). `stop_details` (`category`: `cyber`/`bio`/null + `explanation`) documented. Effort default `high`; min cacheable 1,024; high-res images; task budgets, advisor, computer use support 4.8; fast mode on 4.8 (research preview); sampling params → 400. Fast mode on Opus 4.6 deprecated.
- **05-27** `usage.output_tokens_details.thinking_tokens` (final `message_delta` when streaming).
- **05-19** MCP tunnels research preview; Managed Agents self-hosted sandboxes; update MCP/tool config of active sessions; >100K-char tool outputs spilled to a sandbox file.
- **05-18** Web search returns richer SEC filing data. **05-13** Cache diagnostics public beta (`diagnostics.previous_message_id` → `cache_miss_reason`; `cache-diagnosis-2026-04-07`).
- **05-12** Fast mode on Opus 4.7. **05-11 — Claude Platform on AWS launched** (Claude API on Anthropic-managed infra via AWS endpoints, IAM auth, AWS billing/CCU).
- **05-06** Managed Agents multiagent orchestration + Outcomes public beta; `mcp_oauth` credential refresh; webhooks; session/event filters. Dreams research preview (`dreaming-2026-04-21`).
- **05-04** Workload Identity Federation (OIDC tokens → `POST /v1/oauth/token`).

### April
- **04-30** **`context-1m-2025-08-07` retired for Sonnet 4.5 and Sonnet 4** (no effect; >200k errors).
- **04-29** Claude API skill (open-source Agent Skill). **04-24** Rate Limits API. **04-23** Managed Agents memory public beta. **04-20 Claude Haiku 3 retired.**
- **04-16 — Claude Opus 4.7 (`claude-opus-4-7`)**: $5/$25, new tokenizer, breaking changes vs 4.6 (see migration guide); Claude in Amazon Bedrock open to all (`/anthropic/v1/messages`, 27 regions); **task budgets** beta (`task-budgets-2026-03-13`); high-res images (2576 px long edge, ~3x image tokens); **`xhigh` effort**.
- **04-14** Sonnet 4 / Opus 4 deprecation announced (retire 06-15). **04-09** **Advisor tool** public beta (`advisor-tool-2026-03-01`).
- **04-08** **Claude Managed Agents public beta** (`managed-agents-2026-04-01`); **`ant` CLI** launched.
- **04-07** Claude Mythos Preview (gated, Glasswing); Messages API on Amazon Bedrock research preview (`/anthropic/v1/messages`, us-east-1).

### March
- **03-30** Batches `max_tokens` cap 300k for Opus 4.6 / Sonnet 4.6 (`output-300k-2026-03-24`); 1M beta retirement for Sonnet 4.5/4 announced for 04-30.
- **03-18** **Models API capability fields**: `max_input_tokens`, `max_tokens`, `capabilities` on `GET /v1/models` and `/v1/models/{id}`.
- **03-16** `thinking.display` (`"omitted"` keeps `signature`). **03-13** **1M context GA (no header) for Opus 4.6 / Sonnet 4.6** at standard pricing; dedicated 1M rate limits removed; media limit 100 → 600 images/PDF pages per request at 1M.

### February
- **02-19** **Automatic caching** (top-level `cache_control`). **Sonnet 3.7 and Haiku 3.5 retired** (Haiku 3.5 stays on Bedrock/Vertex). Haiku 3 deprecation announced (retire 04-20).
- **02-17 — Claude Sonnet 4.6 (`claude-sonnet-4-6`)**: extended thinking, 1M context (beta). **Code execution free with web search/web fetch.** Web search and programmatic tool calling header-free; dynamic filtering for web search/fetch; code execution, web fetch, tool search, tool use examples, memory tool header-free.
- **02-07** **Fast mode** research preview on Opus 4.6 (`speed` param, up to 2.5x). 
- **02-05 — Claude Opus 4.6 (`claude-opus-4-6`)**: adaptive thinking recommended (`enabled` deprecated), no prefill; **effort GA** (no header) and on Opus 4.6; **compaction API** beta; **data residency** (`inference_geo`, US ×1.1 for models after 2026-02-01); 1M beta on Opus 4.6 (long-context pricing >200k at the time); **fine-grained tool streaming header-free**.

### January
- **01-29** **Structured outputs GA** on Claude API (Sonnet 4.5, Opus 4.5, Haiku 4.5): `output_format` → `output_config.format`; still beta on Bedrock/Foundry.
- **01-12** console.anthropic.com → platform.claude.com redirect. **01-05 Claude Opus 3 retired.**

## 2025

### Q4
- **12-19** Haiku 3.5 deprecation announced. **12-04** Structured outputs on Haiku 4.5.
- **11-24 — Claude Opus 4.5 (`claude-opus-4-5-20251101`)**; **programmatic tool calling** public beta; **tool search tool** public beta; **effort parameter** public beta (Opus 4.5); client-side compaction in Py/TS SDK `tool_runner`.
- **11-21** `search_result` blocks on Bedrock header-free. **11-19** Docs moved to platform.claude.com/docs. **11-18** **Claude in Microsoft Foundry** launched.
- **11-14** **Structured outputs** public beta (`structured-outputs-2025-11-13`; Sonnet 4.5, Opus 4.1).
- **10-28** Sonnet 3.7 deprecation announced; **Sonnet 3.5 models retired**; context editing adds `clear_thinking_20251015`.
- **10-16** **Agent Skills** (`skills-2025-10-02`; `/v1/skills`; requires code execution). **10-15 — Claude Haiku 4.5 (`claude-haiku-4-5-20251001`)**.

### Q3
- **09-29 — Claude Sonnet 4.5 (`claude-sonnet-4-5-20250929`)**; global endpoint pricing on Bedrock/Vertex; new stop reason **`model_context_window_exceeded`**; **memory tool** beta; **context editing** beta (`clear_tool_uses`).
- **09-17** Tool helpers / tool runner beta (Py, TS). **09-16** Rebrand to Claude Console / Claude Docs / Claude Help Center (APIs unchanged).
- **09-10** **Web fetch tool** beta; Claude Code Analytics API. **09-08** C# SDK beta. **09-05** Rate-limit charts in Console. **09-03** Citable documents in client tool results. **09-02** Code execution v2 (Bash + files) public beta. **08-27** PHP SDK beta.
- **08-26** Higher 1M rate limits for Sonnet 4; 1M on Vertex. **08-19** `request_id` in error bodies. **08-18** **Usage & Cost API**; Admin API `GET /v1/organizations/me`.
- **08-13** Sonnet 3.5 deprecation announced (retire 10-28); **1h cache TTL GA**. **08-12** 1M context beta for Sonnet 4 (API + Bedrock). **08-11** Acceleration limits now 429 (were 529). **08-08** `search_result` blocks GA (API, Vertex). **08-05 — Claude Opus 4.1 (`claude-opus-4-1-20250805`)** (cannot set both `temperature` and `top_p`).
- **07-28** `text_editor_20250728` (`max_characters`). **07-24 / 07-17** Rate limits raised for Opus 4 / Sonnet 4. **07-21 Claude 2.0, 2.1, Sonnet 3 retired.** **07-03** `search_result` blocks beta (`search-results-2025-06-09`).

### Q2
- **06-30** Opus 3 deprecation announced. **06-11** **Fine-grained tool streaming** beta (`fine-grained-tool-streaming-2025-05-14`).
- **05-22 — Claude Opus 4 and Sonnet 4**: summarized thinking with encrypted `signature`; **interleaved thinking** beta (`interleaved-thinking-2025-05-14`); **Files API** beta; **code execution tool** beta; **MCP connector** beta; `top_p` default 0.999 → 0.99 (0.95–1 allowed with thinking); Go SDK stable. **05-21** Ruby SDK stable. **05-07** **Web search tool**. **05-01** `cache_control` must be on the parent `tool_result` / `document.source` block.
- **04-09** Ruby SDK beta.

### Q1
- **03-31** Java SDK stable; Go SDK beta.
- **02-27** URL sources for images and PDFs; `tool_choice: none`; `tools` optional when replaying `tool_use`/`tool_result`; **OpenAI-compatible endpoint**.
- **02-24 — Claude Sonnet 3.7** (extended thinking); vision on Haiku 3.5; token-efficient tool use; `bash_20250124`, `text_editor_20250124` (no header), `computer_20250124` (`computer-use-2025-01-24`).
- **02-10** `anthropic-organization-id` response header. **01-31** Java SDK beta.
- **01-23** **Citations**; plain-text and custom-content documents. **01-21** Claude 2 / 2.1 / Sonnet 3 deprecation announced. **01-15** Caching reads longest cached prefix automatically; prefill with tools. **01-10** Caching optimized for Batches.

## 2024 (context)
12-19 Batches delete endpoint · 12-17 Models API, Batches, token counting, prompt caching, PDF support GA (no headers); Java/Go SDK alpha · 11-21 Admin API · 11-20 TPM → ITPM/OTPM · 11-04 Haiku 3.5 (text-only) · 11-01 token counting, PDF support · 10-22 computer use tools + Sonnet 3.5 (Oct) · 10-08 Batches beta; relaxed turn ordering · 10-03 `disable_parallel_tool_use` · 09-10 Workspaces · 08-22 CORS/browser SDK · 08-19 8k output default Sonnet 3.5 · 08-14 prompt caching beta · 06-20 Sonnet 3.5 · 05-30 tool use GA.