Source Intelligence
Follow Discord

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All releases Home ←olderv2.1.34 v2.1.37newer→

Claude Code v2.1.36

5 entries read diff v2.1.34 → v2.1.36 Markdown

This release introduces Fast Mode, a new high-speed output mode for Opus 4.6 that uses the same model with faster token generation. Fast mode is billed as extra usage at a premium rate with separate rate limits, and can be toggled with the new /fast command.

Find
Pick an entry · j / k steps through
5 entries

Changesopen

Fast Mode#

Feature flag
tengu_penguins_enabled On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.36: no gate table built for this version

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.36. It isn't a statement about your account. What a flag value here can and cannot tell you

What

High-speed output mode for Claude Opus 4.6 that provides faster token generation without switching to a different model. Currently available as a research preview.

Usage
# Toggle fast mode from the prompt
/fast

# Or configure in settings.json
{
  "fastMode": true
}
Details
  • Uses the same Opus 4.6 model with accelerated output generation
  • Billed as extra usage at a premium rate with separate rate limits
  • Interactive toggle shows current status: "Fast mode ON" or "Fast mode OFF"
  • When enabled, displays with the penguin icon (↯) and orange color theming
  • Has its own rate limits; when reached, enters a cooldown period and automatically re-enables when reset
  • Model automatically switches to Opus 4.6 if not already selected

Availability:

  • Requires a paid subscription
  • Requires extra usage billing to be enabled (/extra-usage)
  • Requires the native binary (not available via npm install)
  • Not available on Bedrock, Vertex, Foundry, or in the Agent SDK
  • Organizations can disable fast mode for their accounts

Rate Limiting:

  • Displays "Fast limit reached and temporarily disabled · resets in X" when hitting limits
  • Shows "Fast limit reset · now using fast mode" when cooldown expires
  • Tracks remaining time to reset in the UI

Promotions:

  • May show discount percentages for extra usage (e.g., "50% off through [date]")
Evidence

Fast mode system (search for "Fast mode", "tengu_penguins_enabled", "/fast")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

New User Setting: fastMode#

What

New boolean setting to persist fast mode state across sessions.

Usage
{
  "fastMode": true
}
Details
  • When true, fast mode is enabled
  • When absent or false, fast mode is off
  • Can be set via the /fast command or directly in settings.json
Evidence

Setting schema (search for "When true, fast mode is enabled")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Enhanced Opus 4.6 Promotional Messaging#

Promotional messages now include fast mode mentions for users who have extra usage enabled:

  • "Opus 4.6 is here · $50 free extra usage · Try fast mode or use it when you hit a limit /extra-usage to enable"
  • "Opus 4.6 is here · Try fast mode"
Evidence

Promotional strings (search for "Try fast mode")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Fast Mode System Prompt Context#

The system prompt now includes <fast_mode_info> context explaining fast mode to Claude: > "Fast mode for Claude Code uses the same Claude Opus 4.6 model with faster output. It does NOT switch to a different model. It can be toggled with /fast."

Evidence

System prompt template (search for "<fast_mode_info>")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Interactive Fast Mode Toggle UI#

The /fast command provides an interactive toggle interface with:

  • Current ON/OFF status with visual highlighting
  • Tab to toggle, Enter to confirm, Esc to cancel
  • Rate limit status and reset countdown when in cooldown
  • Link to documentation: https://code.claude.com/docs/en/fast-mode
  • Displays pricing information and any active discounts
Evidence

Toggle UI component (search for "Tab to toggle · Enter to confirm")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Verbatim
Official · Anthropic

Anthropic’s official release notes

Published verbatim by Anthropic for v2.1.36. Text is unmodified from the upstream changelog. Everything else on this page came out of the bundle instead, which is why the two lists don't match.

  • Fast mode is now available for Opus 4.6. Learn more at https://code.claude.com/docs/en/fast-mode
Read it on GitHub →
System prompt

The system prompt was not captured for this release, so this page cannot say whether it moved.

Which releases were captured →