DevAgentRadar → Claude Code

You are helping me adopt a real coding-assistant change. Work only from the facts below. Do not invent features.

Context

Assistant: Claude Code Proposal: Set CLAUDE_CODE_SUBAGENT_EFFORT so subagents no longer inherit session effort Summary: Claude Code v2.1.316 adds CLAUDE_CODE_SUBAGENT_EFFORT so unnamed subagents use a pinned effort instead of inheriting the session. VS Code ultrathink now runs at xhigh. Disable ultrathink if needed, and move Opus 4.8 fast-mode traffic to Opus 5.5 before 30 Nov 2026. Primary source: https://github.com/anthropics/claude-code/releases/tag/v2.1.316

Why it matters

Subagents used to inherit the parent session's effort when a task did not name one. v2.1.316 adds CLAUDE_CODE_SUBAGENT_EFFORT to set that default independently, so a high-effort parent does not raise every nested agent. That matters because VS Code ultrathink now runs its turn at xhigh effort and shows a rainbow in the chat box, matching the terminal. CLAUDE_CODE_DISABLE_ULTRATHINK turns the ultrathink keyword off if you do not want those turns. Fast mode for Opus 4.8 is deprecated 30 October 2026 and removed 30 November 2026; after removal, fast-mode requests on Opus 4.8 return an error and do not fall back to standard Opus 4.8—migrate to Opus 5.5 to keep the speedup. /model <id> now warns when this version does not recognize the id and auto-compact will assume a 200K context window. Upgrade also stops --restricted sessions from uploading files outside the working directories when a Read allow rule covered them.

Suggested actions

1. In the environment that launches Claude Code v2.1.316+, set CLAUDE_CODE_SUBAGENT_EFFORT to the effort subagents should run at when a task does not name one, instead of inheriting the session (VS Code ultrathink turns now run at xhigh).
2. If you want the ultrathink keyword off, run: export CLAUDE_CODE_DISABLE_ULTRATHINK=1
3. Replace Opus 4.8 fast-mode model settings with Opus 5.5 before 30 November 2026. Fast mode for Opus 4.8 is deprecated 30 October 2026; after removal, those requests return an error and do not fall back to standard Opus 4.8.
4. Use /model only with ids this Claude Code version recognizes; unrecognized ids now warn and auto-compact assumes a 200K context window.
5. Upgrade to Claude Code v2.1.316 before using --restricted, so a Read allow rule no longer causes uploads of files from outside the working directories.

Config surfaces this release may change

• subagent definitions — check your repo before applying
• hooks — check your repo before applying
• permission rules — check your repo before applying
• background and headless runs — check your repo before applying
• MCP servers — check your repo before applying
• skills — check your repo before applying
• settings files — check your repo before applying
• agent context files — check your repo before applying
• context and compaction settings — check your repo before applying

After you finish

Do not report this as applied to DevAgentRadar. You cannot write the visitor's loop.

Tell the human: open https://devagentradar.com/proposals/claude-code-v2-1-316-set-claude-code-subagent-effort-so-subagents-no-lon and mark Applied, Skipped, or Failed. Proposal id: 7da1571f-e388-4261-8d4d-ac2403091637

Your job

1. Restate the change in one sentence.
2. Propose a minimal plan for my repo (or a throwaway pilot).
3. Implement only what I approve; prefer small diffs and tests.
4. Call out risks (permissions, breaking APIs, cost).

Start by confirming you understood the proposal.