release aidev SIG 5/5

Claude Code 2.1.219: Claude Opus 5 becomes the default Opus model

Adds claude-opus-5 with a 1M context window as the new default Opus model, priced at $10/$50 per Mtok in fast mode. Also raises the default subagent nesting depth from 1 to 3 and drops Opus 4.7 from fast mode, both of which change behavior for existing setups.

PUBLISHED2026-07-24
OBSERVED2026-08-11
AGE18d
SOURCES1
  • Added Claude Opus 5 (claude-opus-5), now the default Opus model — 1M context, fast mode at $10/$50 per Mtok
  • Removed Opus 4.7 from fast mode; /fast now applies to Opus 5 and Opus 4.8
  • The claude-api skill now defaults to Claude Opus 5, with a migration path from Opus 4.8
  • Subagents can spawn nested subagents up to depth 3 by default (was 1); set CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH=1 to disable nesting
  • Added sandbox.network.strictAllowlist to deny non-allowlisted hosts for sandboxed commands without prompting
  • Added a DirectoryAdded hook firing after /add-dir or the SDK register_repo_root control request
  • Added mcp_server_errors to the headless stream-json init event, listing --mcp-config entries skipped by config validation
  • Added nested subagent forwarding in stream-json for depth-2+ subagents under --forward-subagent-text
  • Added the workflowSizeGuideline settings key; dynamic workflows now default to a medium size guideline (aim for fewer than 15 agents)
  • claude mcp list and /mcp now show HTTP status and error text on connection failure
  • Fixed claude -p dropping an already-produced answer when a turn dies on a mid-stream API error
  • Fixed CLAUDE_CODE_GIT_BASH_PATH on Windows being used when the path isn't a bash/sh binary; it's now ignored with a warning
new-modelmodel-supportpricingcontext-windowfeaturefix

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