What's new in Claude

Auto mode now blocks tampering with session transcript files; fixed --json-schema silently producing unstructured output with invalid schemas. Multiple reliability fixes: message loss at --max-turns limit, Windows worktree deletion issues, background agent state inconsistencies, and plugin LSP server initialization failures.

Fixed hook events not streaming during SessionStart hooks in headless sessions, which could cause remote workers to be idle-reaped mid-hook before completing setup.

Login expiration warnings added to prevent background session interruptions with automatic recovery from stale daemon tokens. Fixed subagents silently stopping when returning to claude agents, memory/CPU regression in interactive sessions, stale PATH on Windows, and worktree-isolated subagents running in wrong directories.

claude mcp login: authenticate a configured MCP server directly from your shell instead of the interactive /mcp menu, and clear stored credentials with claude mcp logout.

Shell mode explains command output: running ! npm test now returns an explanation of the result without needing a follow-up prompt.

/rewind across /clear: /rewind can now resume a conversation from before a /clear was run, restoring full prior context.

Background subagent permission prompts: instead of auto-denying, subagents now surface permission prompts in the main session so you can approve them without the task failing.

Claude Fable 5 and Claude Mythos 5 restored after a brief suspension. See Anthropic's statement on the redeployment for full details.

Claude Sonnet 5 (claude-sonnet-5) launched at introductory pricing of $2/$10 per MTok through August 31, 2026. Supports 1M token context window and 128k max output. Note: adaptive thinking is on by default; manual extended thinking and non-default sampling params now return 400 errors.

Managed Agents event deltas: session event streams now support streaming deltas so you can preview agent message text as it's generated, before the complete event arrives. Opt in via event_deltas[] on the events stream endpoint.

Per-session agent config overrides: when creating a Managed Agents session, pass agent: {type: "agent_with_overrides"} to replace the model, system prompt, tools, MCP servers, or skills for that session without modifying the agent definition.

Published a definitive Claude Code loops guide, explaining how the team categorizes loops by trigger, stop criteria, and primitive — covering the full range of loop patterns now available in Claude Code.

Claude Sonnet 5 is now the default model for Free and Pro plans. Also announced: Claude Science, a new product optimized for pharmaceutical research and scientific lab use cases.

"Hello from Code with Claude London!" — Boris has been attending Code with Claude community events globally and continues sharing that he hasn't written a line of code himself in 2026, letting Claude Code handle it all.

"A Field Guide to Fable: Finding Your Unknowns" — Thariq published a guide on effectively working with Claude Fable 5, exploring how to surface the model's unknowns and get the most out of its reasoning capabilities.