Claude Code v2.1.316: Opus 4.8 Fast Mode Deprecated, New Env Vars

Claude Code v2.1.316 has 55 changelog entries: 34 fixes, 10 additions, 5 improvements, 5 changes, and 1 deprecation. The deprecation is the one to act on: fast mode for Opus 4.8 will be removed on November 30, 2026. The release also adds three environment variables, gives Claude apps gateway administrators pooled budgets, layered policies and Bedrock guardrail tagging, changes how server-managed settings apply on Team and Enterprise logins, and closes several permission gaps. If you use fast mode on Opus 4.8, run a gateway, or manage settings for an organization, read the first three sections.

Opus 4.8 Fast Mode Is Deprecated

Fast mode for Opus 4.8 is deprecated as of October 30, 2026, and will be removed on November 30, 2026.

Date	What happens
October 30, 2026	Fast mode for Opus 4.8 is deprecated
November 30, 2026	Fast mode for Opus 4.8 is removed

After removal, fast mode requests on Opus 4.8 return an error. They do not fall back to standard Opus 4.8, so anything that still asks for fast mode on Opus 4.8 after that date fails rather than running on the standard model. The changelog’s instruction is to migrate to Opus 5.5 to keep the speedup.

If you use fast mode on Opus 4.8, make the switch before November 30. Our Opus 4.8 fast mode migration guide covers the move.

What’s New

Three Environment Variables

CLAUDE_CODE_SUBAGENT_EFFORT sets the effort level subagents run at when nothing else names one, instead of inheriting the session’s. Our effort levels guide covers the other places effort can be set.
CLAUDE_CODE_DISABLE_ULTRATHINK turns the ultrathink keyword off.
CLAUDE_CODE_DISABLE_LOOPED_CROSS_CERT_DROP keeps system cross-certificates that certify each other in a loop, for servers whose private CA needs one.

Certificate trouble is also easier to diagnose: SSL certificate errors now name the likely causes, among them a server that leaves out an intermediate certificate, and the fix for each.

Claude Apps Gateway

Gateway administrators get three additions:

Pooled group budgets. One monthly budget that a group’s members share, on top of each member’s own limit. It is set with pooled_budget on the spend limits admin API.
managed.policy_mode: layered. Every policy that matches a developer applies, each merged over the ones listed below it, rather than only the first.
guardrail.input_tagging on Bedrock upstreams. It wraps prompts in the input tags that an Amazon Bedrock guardrail’s prompt attacks filter needs. With all_messages_and_system, the system prompt is tagged as well.

Two gateway fixes and a VS Code addition go with them:

A stricter model check. The gateway now checks every model a request names against availableModels, deniedModels and models. A request that names a blocked model gets a 400 that names the field.
claude auth login no longer refuses to run where managed settings require a Claude apps gateway. In a terminal, it now shows the gateway sign-in.
VS Code gains sign-in to a Claude apps gateway from the chat panel, with no terminal needed.

Cloud Sessions and Code Review

Forms from MCP servers. Cloud sessions gain a form card, so you can fill in or decline a form an MCP server asks for. Previously the request was canceled without you seeing it.
“Catching up…” now shows while a cloud or Remote Control session you switch back to is still bringing its messages up to date.
Findings by severity. The Code Review analytics page gains a card showing the period’s total findings, a daily chart stacked by severity, and each severity’s count.

Changed Behavior Worth Noting

Server-managed settings on Team and Enterprise logins. Settings fetched from Anthropic’s API now apply without an approval prompt, and a stored copy that doesn’t verify is refused.
autoMode.allow and scheduled tasks. An autoMode.allow list without "$defaults" no longer removes the built-in rule on scheduled-task prompts.
ultrathink in VS Code now runs its turn at xhigh effort and shows in a rainbow in the chat box, as in the terminal.
Blocked models at the gateway. A Claude apps gateway request that names a blocked model now gets a 400 naming the field (see the stricter model check above).
Model aliases on Vertex AI and Amazon Bedrock. When the newest model is not yet available to the account or region, sonnet, opus and haiku now switch to an older model instead of showing an error mid-session.
Network secrets in cloud sessions. Enterprise members can now add and delete network secrets on their own cloud environments, instead of only viewing them.
Claude Tag channel setting. A Slack channel’s Respond automatically switch is now a “How Claude participates” choice, on the channel’s Configure page and in Claude Tag admin settings.

Security and Permission Fixes

Each item below describes a bug this release fixes.

--restricted sessions could upload files from outside the working directories when a Read allow rule covered them.
PowerShell hooks did not block on exit code 2 when the command began with a type cast, param, using or an attribute.
A managed autoMode.allow list without "$defaults" got the built-in exceptions back from a host app’s --settings, a first rule added in /permissions, or /auto-mode-setup.
Auto mode stops went unreported. Cloud sessions and cloud scheduled tasks were not marked as failed when auto mode stopped a turn because the server returned no safety verdict, and claude -p text output sometimes did not say why auto mode stopped a turn while a background agent was still running.
CLAUDE_CODE_AUTO_MODE_SERVER=1 was ignored in sessions started by a host application, such as Claude Desktop, behind a proxy or LLM gateway with experimental betas turned off.
Plugin MCP headersHelper scripts received a corrupted CLAUDE_PLUGIN_ROOT and server URL when a credential-named environment variable was set to a switch value such as 1.

Shell and Tool Fixes

Shell commands are no longer left running on macOS and Linux when Claude Code exits by itself, for example when credentials are refused or a cloud session is archived.
Bash aliases with line breaks in their value (except in Git Bash), and functions whose names start with a dash, are no longer garbled or lost in the Bash tool’s shell.
Bash scripts started from the Bash tool no longer stop after their first command when SHELLOPTS is exported.
On Windows, the Bash tool no longer loses your aliases and functions in Git Bash when the rc file sets errexit and pipefail and only winpty aliases, or none, are defined.
Grep and Glob now return when the search process is killed at the timeout but does not exit, a case seen on Windows.
Some network requests no longer hang when a compressed response is cut off or corrupted.

Models, Subagents, and Sessions

Inherited models stick. Subagents that inherited a parent subagent’s model no longer move to the main model when a background job or message wakes them.
/model <id> warns when this version doesn’t recognize the model and auto-compact will assume a 200K context window. It previously gave no warning.
Invisible characters. Prompts containing invisible characters needed a second Enter to send. Plain prompts now send cleaned on the first Enter, and commands still wait for review.
Plans on resume. A rare case is fixed where resuming a conversation did not restore its plan, when /clear or /resume had been run while part of that conversation was still being saved.
SDK register_repo_root now loads the CLAUDE.md of a directory outside the working directory (with CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD=1).
The Artifact tool no longer shows ? for artifact database access rules at the self level, and now quotes those rules back when it refuses a republish that would drop them.

Workflow Improvements

/code-review from the Code tab in Claude Desktop or on the web: cloud and claude remote-control sessions now show the findings card, not a plain-text list.
/diff on large repositories: each refresh usually runs one fewer full-repository git command, and refreshes are spaced out when git is slow.
No GitHub remote: when /ultrareview, a cloud session or a cloud agent finds no GitHub remote, the message now says to create a repository at github.com/new, and /ultrareview no longer suggests a gh command that gh rejects.

Cloud Sessions, Self-Hosted Runner, and Claude Tag

Cloud sessions: the Changes pane’s note about what the list leaves out is now a badge beside the branch name, not a row above the diff. File search in the Files pane no longer shows folders as ../.. paths after Claude changes directory; results show their path from the project’s root.
Self-hosted runner: a message sent while Claude was working is no longer answered after a Stop once the session’s process has been replaced, and an MCP server’s on/off switch is no longer sometimes lost when a session moves to a new machine.
Claude Tag: Claude no longer refuses to edit or append to a canvas it made in a Slack channel, from that channel, once the canvas is also shared to another channel or a DM. Untagged replies in a Slack Connect thread no longer go unanswered when both organizations have installed Claude and Slack delivered the reply to the other organization’s app. A cloud scheduled task’s live status checklist in Slack no longer stays half-done: a run can now edit the top-level messages it posted during that run.

VS Code

Besides gateway sign-in from the chat panel and ultrathink at xhigh (both covered above):

The Effort slider, Ultracode switch and model name no longer go missing when the model setting has the [1m] tag, such as opus[1m].
Saved /btw side-question history is no longer deleted too early while a settings file has errors.
A conversation whose plan was approved with “Yes, and manually approve edits” no longer comes back in Auto mode after a reload or restart.

Smaller Fixes

The “hold space to speak” hint no longer uses up its three showings in one session or shows an empty key when push-to-talk is unbound. First-run setup no longer drops words from the security notes and the terminal-setup explanation in narrow terminals. The Enterprise survey card no longer takes a typed 1 or 0 after a short pause; a typed answer now needs Enter.

This page covers all 55 entries; the official changelog has the exact wording of each.

How to Update

Check your installed version: claude --version
Update in place: claude update
If you use fast mode on Opus 4.8, move to Opus 5.5 before November 30, 2026.