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Anthropic SDK Releases — May–June 2026 (Python v0.98–v0.109, TypeScript v0.93–v0.104 + aws/bedrock/vertex/foundry SDKs)

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Source: raw/anthropic-watch-anthropic-sdk-python-tag-v0-{98-0,98-1,99-0,100-0}.md + raw/anthropic-watch-anthropic-sdk-typescript-tag-sdk-v0-{93-0,94-0,95-0,95-1}.md (Stainless-generated GitHub releases, week of 2026-05-04)

The Python and TypeScript SDKs shipped a coordinated set of releases over four days (May 4–7) that landed three significant features: improved Managed Agents APIs (multi-agent, outcomes, webhooks, vault validation), Workload Identity Federation + interactive OAuth + auth profiles, and OIDC workspace targeting. Both SDKs version-locked together (Python v0.98 ↔ TS v0.93, Python v0.99 ↔ TS v0.94, Python v0.100 ↔ TS v0.95) so feature parity is maintained release-by-release.

Key Takeaways

  • Python v0.98.0 / TS v0.93.0 (May 4) — Three features land together: improved Managed Agents APIs (Python only — TS v0.93 only ships the auth piece), Workload Identity Federation + interactive OAuth + auth profiles, and support setting headers via env (Python only). Python also gets bug fixes for stop_details propagation in streaming, multipart file array field-name format, and an async-client base URL bug for Vertex us/eu multi-region.
  • Python v0.98.1 (May 4, hours later) — Typo-only chore release.
  • Python v0.99.0 / TS v0.94.0 (May 5) — Single feature: client: allow targeting a workspace for OIDC federation token exchange. Lets OIDC users scope tokens to a specific Anthropic workspace.
  • Python v0.100.0 / TS v0.95.0 (May 6) — Major feature: full Managed Agents surface lands. add support for Managed Agents multiagents and outcomes, webhooks, vault validation. Bug fix: Adjust webhook configuration. This is the SDK side of the same Managed Agents update covered in the Cookbook commits and the May 7 conference announcement.
  • TS v0.95.1 (May 7) — Chore: redact api-key headers in debug logs. Security hygiene.
  • Python v0.101.0 / TS aws-sdk v0.3.0 (May 11) — Both releases add the AWS client for Claude Platform on AWS, shipped the same day as the AWS GA announcement. Python v0.101.0 also fixes a missing f-string prefix in a file-type error message; example scripts bumped to claude-sonnet-4-5-20250929 and shebangs migrated from poetry to uv.
  • TS sdk-v0.95.2 (May 11) — Patch-only release; no public-feature notes in the changelog body (full changelog sdk-v0.95.1...sdk-v0.95.2 shows no entries).
  • Python v0.102.0 / TS sdk-v0.96.0 (May 13) — Two features land in lockstep: (1) BetaManagedAgentsSearchResultBlock types — new content-block type for Managed Agents search results, surfaced through the API spec; first-class type support for the “agent searched, here’s the result block” interaction pattern that pairs with the W21 CMA Sessions MCP server bridge. (2) Cache diagnostics beta — opt-in beta for surfacing prompt-cache hit/miss diagnostics. Important for cost-optimization work; closes the “is my prompt cache actually hitting?” measurement gap for SDK clients and unlocks the measurement layer that Prompt Caching for Agencies depends on. Python v0.102.0 also adds internal/types: support eagerly validating pydantic iterators (better validation of streaming type-checked iterators). TS sdk-v0.96.0 includes a zod bug fix ensuring only zod/v4 types are used.
  • Python v0.103.0/v0.103.1 + TS sdk-v0.97.0/v0.97.1 (May 19, same-day .0 → .1) — Self-hosted-sandbox helpers + same-day SessionToolRunner ownership patch. v0.103.0 / v0.97.0 land the SDK side of the Week 22 CMA self-hosted-sandboxes story (EnvironmentWorker, work.poller(), AgentToolContext, tool_runner(), sessions.update() mid-session updates, >100K MCP-output file offload). v0.103.1 / v0.97.1 ship a hours-later patch (runner: skip tool calls SessionToolRunner does not own — Python #1817 / 9425c6a, TS 9987379) — when a worker processes a session it doesn’t own (overlapping pollers, stale poller after migration), the runner now skips the tool call instead of executing it. Adoption rule: skip the .0; ship .1. Full coverage in Week 22 Digest including the cookbook scrub that re-points templates at the patched SDKs.
  • Python v0.104.0 / TS sdk-v0.98.0 (May 21) — Single feature, version-locked: thinking-token-count beta — adds estimated token counts in thinking-block deltas when streaming (Python 80d0fdf, TS 0528d47). Lets clients track extended-thinking token spend during a stream rather than only in the final usage object — the streaming-side measurement complement to the cache-diagnostics beta (v0.102) above, and directly useful for budgeting extended-thinking cost on long agentic runs.
  • Python v0.104.1 (May 21, patch) — Bug-fix-only: streaming: carry encrypted_content through beta compaction accumulator (#1821, f7a720c). When streaming responses are accumulated under the context-compaction beta, the accumulator now preserves encrypted_content blocks instead of dropping them — relevant to anyone running long agentic sessions with compaction enabled (the encrypted reasoning carried across compaction boundaries was being lost in the streaming-accumulator path). No TS counterpart in this patch.
  • Python v0.105.0 / TS sdk-v0.100.0 (May 28) — Opus 4.8 support, version-locked. Same headline feature in both clients: api: Add support for claude-opus-4-8, mid-conversation system blocks, and usage.output_tokens_details (Python f18b014, TS bb0bf27). Adds (1) the claude-opus-4-8 model id as first-class, (2) mid-conversation system blocks (inject system-role content partway through a conversation), (3) usage.output_tokens_details for finer output-token accounting. Python v0.105.0 adds one TS-absent extra — support custom file size caps (#1825, 7e5f944) — plus a chore renaming the cookbook example managed-agents private-sandbox-worker → self-hosted-sandbox-worker (#1822). This is the SDK side of the Week 23 Opus 4.8 launch. Bump to v0.105.0 / sdk-v0.100.0 for Opus 4.8.
  • TS sdk-v0.100.1 (May 29) — patch. streaming: carry encrypted_content on beta compaction blocks (#1025, eccddf3) — the TS port of the Python v0.104.1 fix; the encrypted-reasoning-across-compaction fix has now reached both SDKs. Plus a standardwebhooks lockfile chore (5e9b523).
  • Python v0.105.1 (May 29) — chore-only. internal: use Trusted Publishing for PyPI releases (1d04fc5). OIDC-based PyPI publishing; no public-facing change.
  • Python v0.105.2 (May 29) — empty release. Changelog body has no entries (v0.105.1...v0.105.2). Bare version bump.
  • TS aws-sdk-v0.3.1 + foundry-sdk-v0.2.4 (May 29) — chore-only. Both ship the identical standardwebhooks lockfile chore (5e9b523), cut from the same commit as sdk-v0.100.1. Pure plumbing. (First appearance of a foundry-sdk release in this article — the Microsoft Foundry sub-package, pairing with Opus 4.8 / dynamic-workflows availability on Foundry.)
  • The auth story is the under-the-radar headline. Workload Identity Federation, interactive OAuth, auth profiles, OIDC workspace targeting — together these change how SDK clients authenticate inside enterprise CI / cloud / Vertex environments.
  • Stainless-generated releases. All releases authored by stainless-app[bot] — Stainless is Anthropic’s SDK code-gen pipeline. The version-locking between Python and TS releases reflects this single source of truth.

June 2026 releases

A coordinated 2026-06-05 batch (stainless-app[bot]) bumped every SDK in lockstep — two real features plus housekeeping:

  • Packages: Python v0.106.0, TS sdk-v0.101.0, and all four cloud sub-SDKs — aws-sdk v0.4.0, bedrock-sdk v0.30.0, vertex-sdk v0.17.0, foundry-sdk v0.3.0.
  • Feature 1 — Claude Opus 4.1 marked deprecated (api: change across every package, 4ee46f2 / 85068cc). The SDKs now flag claude-opus-4-1 as deprecated, consistent with Opus 4.8 as the current flagship.
  • Feature 2 — client middleware support (client: add support for middleware, 9b01120) lands in the TS main SDK and all four cloud sub-SDKs — wrap requests/responses with a middleware chain. The v0.101.0 timeout fix scopes the request timeout to the inner fetch only, not the middleware chain (#40).
  • Python v0.106.0 extras: Foundry client copy() / with_options() now work (94146ac); transform-schema preserves $defs when the schema root is a $ref (#1642).
  • TS sdk-v0.101.0 extras: streaming fixes — carry stop_details through beta message_delta accumulation (ed3fec7), and correctly parse JSON numbers in scientific notation (#9).
  • Both: security reports now point to Anthropic’s HackerOne program (docs).
  • Adoption: bump to Python v0.106.0 / TS sdk-v0.101.0 for the middleware hook and the Opus-4.1-deprecation flag; Bedrock/Vertex/Foundry/AWS users get the same via the sub-SDK bumps.

2026-06-09 batch — Managed Agents deployments + Fable 5 hooks (Python v0.109, TS sdk-v0.104):

  • Python v0.109.0 / TS sdk-v0.104.0 — api: add support for Managed Agents *deployments* and environment-variable credentials. The SDK side of the W25 Managed-Agents-deployments throughline: schedule a deployed agent and feed it secrets via vault-backed env-var credentials (substituted at egress with networking allowlists). See Managed Agents.
  • Python v0.109.1 / TS sdk-v0.104.1 — api: add frontier_llm refusal category. The SDK-side hook for Fable 5’s topic-gated fallback: a refused request returns this category and the server-side fallback (to Opus 4.8) fires.
  • Adoption: bump to Python v0.109.x / TS sdk-v0.104.x if you deploy Managed Agents or build on Fable 5.

2026-06-15 — model-retirement cleanup (Python v0.109.2, TS sdk-v0.104.2):

  • Python v0.109.2 / TS sdk-v0.104.2 (June 15) — chore. api: remove retired models from API and SDKs (Python d4bcfcc, TS a942876). Drops models already retired from the API surface out of both clients — the housekeeping tail of the model-deprecation thread above (Opus 4.1 was flagged deprecated in the 06-05 batch). No new feature or API capability; bump only to track the trimmed model list. Version-locked across both SDKs as usual.

What’s actually new in Managed Agents

Per the v0.100.0 / v0.95.0 changelog: multiagents, outcomes, webhooks, vault validation. Reading the four together:

  • multiagents — programmatic API for the Managed Agents coordinator pattern (the cookbook example uses it for a coordinator-runs-three-specialists sales-proposal workflow).
  • outcomes — grader-and-revise loop where a writer drafts, a grader checks against a rubric, feedback drives revisions until pass. New Outcome API surface for declaring rubrics + receiving grader feedback in-loop.
  • webhooks — external systems can subscribe to Managed Agents events. The bug-fix line Adjust webhook configuration suggests the spec was tightened post-shipping.
  • vault validation — credential / secrets vault validation surface. Mentioned tersely in the changelog; cookbook coverage doesn’t expand. Open thread.

Auth surface changes

  • Workload Identity Federation (Python v0.98.0 / TS v0.93.0) — Standard pattern for IAM-federated cloud workloads (GCP/AWS/Azure) to authenticate without long-lived API keys. Significant for production workloads that previously relied on storing API keys in environment variables.
  • Interactive OAuth (Python v0.98.0 / TS v0.93.0) — Browser-based OAuth flow for human-driven SDK usage. Pairs with the Claude Code v2.1.126 paste-code path improvement.
  • Auth profiles (Python v0.98.0 / TS v0.93.0) — Multiple named authentication contexts for the same client. Useful for testing across orgs/workspaces.
  • Header-via-env (Python v0.98.0 only) — Set client headers via environment variables. TS not mentioned in the changelog.
  • OIDC workspace targeting (Python v0.99.0 / TS v0.94.0) — Scope OIDC federation tokens to a specific Anthropic workspace.

Try It

  1. Bump Python SDK to 0.100.0 or TS SDK to 0.95.0. This is the version that has the full Managed Agents surface. pip install --upgrade anthropic or npm install @anthropic-ai/sdk@latest.
  2. Use the multiagents API in a coordinator pattern. Walk through the new [[claude-ai/anthropic-cookbook-managed-agents-multiagent-outcomes|CMA_coordinate_specialist_team cookbook]] to see the API in action.
  3. Try the outcomes grade-and-revise loop. Same cookbook covers CMA_verify_with_outcome_grader.ipynb — a writer drafts, a grader checks, feedback drives revisions. Six-principle rubric-writing table + failure-mode discussion included in the cookbook.
  4. Adopt Workload Identity Federation in CI. If you’re running Claude SDK in a GitHub Actions / GitLab CI / cloud workload that has IAM federation set up, swap your ANTHROPIC_API_KEY env var for the federated auth pattern. Check the SDK release notes for the exact client-config snippet.
  5. Verify TS debug-log redaction (TS v0.95.1). Set DEBUG=* and call the client; confirm api-key headers are now redacted. If you’d been auditing for accidental key leakage in CI logs, this closes the gap.

Update: Anthropic acquires Stainless (2026-05-18 → 2026-05-19)

[Reddit signal — r/ClaudeAI 2026-05-19] reddit-1thkkrb (Ok-Constant6488, 107 score / 54 comments): Anthropic acquired Stainless on Monday 2026-05-18 for a reported $300M+. The hosted product is winding down — new signups stopped Monday, new SDK and MCP server generations stopped Monday, existing customers keep what they’ve already generated but the pipeline is closed. ~40-50 engineers including founder Alex Rattray (previously built Stripe’s patented SDK generation system) join Anthropic’s Platform Engineering org under Katelyn Lesse. Anthropic now owns:

  1. The engineering team behind the dominant MCP-server generator.
  2. The generator technology, templates, language-specific runtimes, and OpenAPI extensions Stainless invented for SDK-specific edge cases.

Reading. All the SDK releases cataloged above were already authored by stainless-app[bot] — Anthropic now owns that pipeline outright instead of renting it. The strategic framing in the Reddit post: Anthropic created MCP, donated it to the Linux Foundation in December 2025, and now owns the dominant implementation toolchain. The protocol is vendor-neutral on paper; the implementation toolchain isn’t. Concentration risk for orgs that want diversity in their MCP-server stack — Cloudflare’s MCP server framework and Pulse MCP become strategically important alternatives. The 6-month Anthropic M&A pattern (Dec 2025 Bun → Feb 2026 Vercept → Apr 2026 Coefficient Bio → May 2026 Stainless) reads as buying the integration layer around the model, not training infrastructure. Primary sources cited in the Reddit post: Anthropic’s announcement and brightbean.xyz/blog/anthropic-acquires-stainless-sdk-mcp-power-play/.

Open Questions

  • Vault validation specifics. Changelog line is one phrase. Open question: does this connect to the WEO-internal vault patterns or to a generic secrets-vault interface?
  • Header-via-env asymmetry. Python v0.98.0 has it; TS v0.93.0 does not. Is this an intentional gap or pending TS implementation?
  • TS v0.94 → v0.95 with no shared chores. TS has a slightly different cadence than Python — v0.95.1 redacts headers but Python does not have a parallel release. Open thread on Stainless drift between SDKs.

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