On 2026-11-06 Anthropic shipped Claude Code v2.1.319 (npm latest=2.1.319; stable still 2.1.311). In the terminal, MCP tool calls run as tasks move to the background immediately and report when done. New permissions.denyInsteadOfPrompting denies calls that would wait on a permission prompt so the turn continues. Also fixes sandbox escape and Bash permission bypass, plus /claude-api latency-optimize.

Key Takeaways

  • ✓Source: GitHub Release v2.1.319 (2026-11-06 17:04Z) + npm @anthropic-ai/claude-code latest=2.1.319
  • ✓MCP: terminal MCP tool calls run as tasks background immediately; CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND restores sync wait
  • ✓Unattended: permissions.denyInsteadOfPrompting denies prompt-waiting calls in terminal, subagents, and teammates
  • ✓Security: fixes sandbox escape via worktree creation and Bash bypass via crafted env prefixes; stable still 2.1.311
  • ✓Developer: /claude-api latency-optimize; /tasks can reopen finished subagents from earlier in the session
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In-Depth Technical Analysis

Core Background & Industry Pain Points

Coding agents in the terminal often stall on long MCP tools or unattended CI/-p jobs stuck on permission prompts. On 2026-11-06 Anthropic shipped Claude Code v2.1.319 (~17:04 UTC). npm latest points to 2.1.319 while stable remains 2.1.311. This release makes background MCP tasks and deny-instead-of-prompt first-class, and clusters sandbox escape plus Bash permission fixes.

Architecture Highlights & Internals

When an MCP server runs a tool call as a task, the terminal backgrounds it immediately and reports when finished; set CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND to wait inside the tool call. permissions.denyInsteadOfPrompting applies in terminal, subagents, and teammates: prompt-waiting calls are denied and the turn continues—no auto-approve. Also adds /claude-api latency-optimize plus gateway spend views and pooled budget conflict rules.

Authoritative Benchmarks & Measured Scores

No coding-benchmark scores for this build. Verifiable: GitHub Release timestamp 2026-11-06T17:04:01Z; npm view @anthropic-ai/claude-code version returns 2.1.319. Release notes list sandbox escape when creating a worktree and Bash bypass via crafted environment prefixes. Separate User-Agent email-leak reports are out of scope here.

Developer Hands-on Guide

Upgrade with npm i -g @anthropic-ai/claude-code@latest or release binaries. For unattended pipelines enable permissions.denyInsteadOfPrompting; set CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND=1 for sync MCP waits. Gateway users: with telemetry or feature flags off, auto mode no longer falls back to the built-in classifier. Stable is still 2.1.311—regression-test before production.

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Up NextClaude Code 2.1.286: stacked permission counts; resume keeps parallel-tool turns; secret redaction & model-fallback hardening
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