October 30 agent guide: Claude Code write blocks and gateway groups

October 30, 2026 is the first of two Claude Code control days. The changelog adds permissions.blockWritesOutsideWorkingDirectories, gateway groups on upstreams, and idle compaction. Opus 4.8 fast mode is deprecated the same day. Layered policy, pooled budgets, and DeepSeek Super-agent land on October 31 and stay in that day’s guide.

What shipped on October 30

Write blocks map to real incidents

blockWritesOutsideWorkingDirectories is the setting that maps to files changing outside the repo. Agents that can write anywhere the OS user can write are one prompt away from that class of accident. Turning the block on does not replace sandboxing, but it removes a common write path. Gateway groups are how an enterprise keeps a shared Claude Code fleet from each developer carrying a private MCP allowlist.

Do not confuse this changelog with the Cursor marketplace packages that used the 2.1.312 and 2.1.313 version numbers on October 29. Official Claude Code on Anthropic’s distribution path is the control plane described here. Incident context: /blog/october-29-cursor-marketplace-mistral-large-4-2026.

Pilot steps

1. 01
   Turn on the write block

   Set permissions.blockWritesOutsideWorkingDirectories on agent hosts. Run one job that previously wrote a file outside the working tree and confirm it is blocked.
2. 02
   Group the gateway

   Put shared fleets on gateway groups instead of copying MCP allowlists into every developer config.
3. 03
   Start the Opus 4.8 fast-mode exit

   Inventory remaining fast-mode traffic. Move it to Opus 5.5 before November 30. There is no fallback on removal day.

Common mistakes

• Treating October 30 as a model upgrade. It is a control release.
• Skipping the write block because a sandbox exists. The two controls stack.
• Leaving Opus 4.8 fast mode pinned until November 30. Removal has no fallback.
• Folding October 31 layered policy into this day. That changelog is the next post.

Conclusion

October 30 is write blocks, gateway groups, and an Opus 4.8 fast-mode clock. Layered policy and pooled budgets wait until October 31.

Related reading

• October 31: DeepSeek Super-agent and Claude Code layered policy: /blog/october-31-deepseek-superagent-claude-code-2026
• October 29: Cursor marketplace incident and Mistral Large 4: /blog/october-29-cursor-marketplace-mistral-large-4-2026
• October 27: Copilot SDK identity and Claude Code 2.1.311: /blog/october-27-agent-guide-copilot-sdk-lfm3-2026
• Agentic AI topic map: /topics/agentic-ai

Need this Claude Code control plane applied to a fleet?

Bacancy Technology reviews write blocks, gateway groups, and model-removal clocks against the systems a team already runs. Speak with the consulting team or use the contact form. Consulting: /consulting/ . Contact: /contact/ .

Sources: Claude Code changelog, Claude blog .