Claude Code 2.1.316: Two Cost Knobs and a Nov 30 Deadline

Claude Code 2.1.316 shipped to npm at 00:42 UTC on October 31, and it hands teams three budget knobs they did not have yesterday.

Two are new environment variables. The third is a deprecation with a hard date on it: November 30.

Subagents stop inheriting your effort level

The headline line in the changelog: CLAUDE_CODE_SUBAGENT_EFFORT "sets the effort level subagents run at when nothing else names one, instead of inheriting the session's."

That inheritance is the quiet cost multiplier in multi-agent setups. Set a session to high effort for a hard design question, and every subagent it spawns — log readers, file summarizers, checklist runners — runs at high effort too. Until this release there was no session-wide default: you named the effort in each subagent prompt, or accepted the inheritance.

It goes in the env block of your settings file. Illustrative example:

{ "env": { "CLAUDE_CODE_SUBAGENT_EFFORT": "low" } }

One caveat worth repeating: the changelog does not enumerate the accepted values. Confirm on your own install before writing it into a shared config.

The ultrathink keyword gets an off switch

CLAUDE_CODE_DISABLE_ULTRATHINK turns the keyword off entirely. The same release aligns VS Code with the terminal: typing ultrathink "now runs that turn at xhigh effort, with a rainbow indicator in the chat box."

That matters because the keyword fires on text, not intent. A pasted terminal log, a doc the agent reads, or a rules file mentioning the word in prose will all trip it — now to the top of the effort range for a whole turn. For teams that want predictable spend, killing the keyword and making effort explicit is the safer default. Solo developers who never paste it by accident lose nothing.

Opus 4.8 fast mode: errors, not fallback, after November 30

This is the item with a deadline. Fast mode for Opus 4.8 was deprecated on October 30 and gets removed on November 30. The detail that turns it from a slowdown into an outage: after removal, "fast mode requests on Opus 4.8 return an error and do not fall back to standard Opus 4.8."

The migration path named in the changelog is Opus 5.5. If a CI script, a managed config, or a settings file selects fast mode on Opus 4.8, the removal turns it into an error rather than a slowdown. This is also the moment to pin exact model IDs rather than aliases.

Three items for teams on the apps gateway

Change	What it does
pooled_budget	One monthly budget shared by a group's members, on top of each member's own limit — team ceilings without per-person lockstep.
managed.policy_mode: layered	Every matching policy now applies, each merged over the ones below it, instead of only the first match winning. Opt-in — audit the stack before enabling.
guardrail.input_tagging	Wraps prompts in the input tags an Amazon Bedrock guardrail's prompt-attacks filter needs, on Bedrock upstreams.

Two fixes that are budget and security stories

Subagents that inherited a parent subagent's model "no longer move to the main model when a background job or message wakes them." In nested delegation, a cheap subagent model was sometimes flipping back to the expensive main model mid-run — a real leak, now closed.

On the security side, --restricted sessions "no longer upload files from outside the working directories when a Read allow rule covered them." A read permission was widening into upload reach.

One numbering detail if you pin versions

The changelog runs 2.1.312, then 2.1.314, then 2.1.316. Version 2.1.313 is the number a trojanized Claude Code extension claimed on Cursor's marketplace last week, so the real release train skipped it; 2.1.315 shipped on October 30 with no changelog entry. Pin to numbers that exist in the release history.

What to watch

Separately, developers report the Claude 5-hour limit draining faster in T3 Code, the Agent SDK and headless claude -p than in the terminal app. T3 Code's maker Theo posted, "I confirmed it's a real bug on Anthropic's side" — but that is his own testing, and as of October 31 Anthropic has not confirmed it or announced a fix. Treat it as an open report, not a known defect, and check /usage first.