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This week in Claude Code · May 17, 2026

Anthropic Dev Digest: Agent SDK Breaking Changes, TypeScript SDK v0.96, and MCP Background Connections

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TLDR;

The Claude Agent SDK Python v0.2.82 ships two breaking changes builders must address now: MCP servers connect in the background by default (sessions start immediately, slow servers surface as 'pending'), and headless/SDK sessions replace TodoWrite with Task tools (TaskCreate, TaskUpdate, TaskGet, TaskList). The TypeScript SDK v0.96.0 adds BetaManagedAgentsSearchResultBlock types and cache diagnostics beta support. A companion v0.1.81 release bundles Claude CLI 2.1.139. Audit any code that reads MCP connection state at turn 1 or accumulates TodoWrite snapshots before your next deployment.

Claude Code & CLI

Agent SDK & Managed Agents

Claude Agent SDK Python v0.2.82: MCP background connections and Task tools replace TodoWrite

  • Two breaking changes land in v0.2.82: MCP servers now connect in the background by default so sessions start immediately and slow servers report status 'pending' in init until ready (set MCP_CONNECTION_NONBLOCKING=0 to restore the previous 5-second blocking wait, or mark a server alwaysLoad: true to require it at turn 1).
  • Separately, headless and SDK sessions replace TodoWrite with four new Task tools (TaskCreate, TaskUpdate, TaskGet, TaskList), requiring consumers to accumulate state by task ID rather than replacing a snapshot list.

Editor’s read: This is the highest-priority item for any team running SDK-driven agents. The TodoWrite removal is a silent runtime break if overlooked.

Action Items

Immediate

  • Audit every SDK session that reads MCP server state at turn 1: slow servers now return status 'pending' by default instead of blocking. Add alwaysLoad: true for any server that must be ready on the first query, or set MCP_CONNECTION_NONBLOCKING=0 to restore the old behavior.
  • Replace all TodoWrite calls in headless and SDK session code with the new Task tools (TaskCreate, TaskUpdate, TaskGet, TaskList). Update any state-accumulation logic to key on task ID rather than overwriting a snapshot list.
  • Upgrade the Anthropic TypeScript SDK to v0.96.0 and update any managed-agent search result handling to use the new BetaManagedAgentsSearchResultBlock types.
  • If your TypeScript project uses zod, verify compatibility with zod v4 after upgrading to SDK v0.96.0, as the release enforces zod/v4-only types.
  • Pin or upgrade claude-agent-sdk to 0.1.81 to pick up the CLI 2.1.139 bundle if you rely on the bundled CLI binary.

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