# Claude Code v2.1.36

> Claude Code v2.1.36, released 7 Feb 2026 (2026-02-07). 5 entries read out of the shipped bundle. Unofficial, and not affiliated with Anthropic.

Web version: https://changelogs.core-directive.com/v/2.1.36

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.

## Changes

### Fast Mode

**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"`)

- Flag `tengu_penguins_enabled`: On for this account, and not off by default (read for one account on one subscription tier against v2.1.36; this account: on, anonymous baseline: on, compiled default: 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.

### 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"`)

### 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"`)

### 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>"`)

### 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"`)