Claude Code 2.1.83 Release: Prompt Caching, Verify Skill, and SDK Updates
Prompt Caching Implementation
Claude Code 2.1.83 introduces prompt caching with a new design document covering how to design prompt-building code for effective caching, including placement patterns and anti-patterns. The feature includes:
- TTL options for cache management
- Top-level auto-placement guidance
- Cache-hit verification via usage fields
- Prefix-match explanation for cache matching
- Silent-invalidator audit reference for debugging
- Architectural guidance for implementation
Skill Updates
The release replaces the verification specialist skill with a new Verify skill that includes:
- Opinionated verification workflow for validating code changes
- Example workflow for verifying CLI changes
- Example workflow for verifying server/API changes
Other skill updates include:
- System reminder for Ultraplan mode to create detailed implementation plans with multi-agent exploration and critique
- Instructions for using the Advisor tool
- Added PHP beta tool runner to the SDK feature table in Build with Claude API skill
Agent and Tool Updates
Agent prompt changes include:
- Dream memory consolidation with ~25KB size cap on index file
- Tightened index entry format to one line under ~150 characters
- Changed verbose-entry demotion guidance to trigger on lines over ~200 characters
Tool updates:
- CronCreate now supports durable mode where jobs can optionally persist to disk and survive session restarts, with guidance on when to use durable vs. session-only
- SendMessageTool significantly condensed from detailed protocol reference to compact quick-reference format
SDK and API Reference Updates
Multiple language SDKs received prompt caching documentation:
- C#: Updated source-verified SDK from 12.8.0 to 12.9.0, added prompt caching cross-reference and cache-hit verification via usage fields
- cURL: Added Prompt Caching section with example, TTL options, top-level auto-placement, and cache-hit verification guidance
- Go: Added Prompt Caching section with system block caching example, TTL options, top-level auto-placement, and cache-hit verification
- Java: Bumped SDK from 2.16.1 to 2.17.0, added prompt caching cross-reference and cache-hit verification via usage fields
- PHP: Added beta tool runner documentation with BetaRunnableTool and toolRunner() examples, structured outputs section with StructuredOutputModel and raw schema approaches, Prompt Caching section, bumped recommended SDK from 0.6 to 0.7
- Python: Expanded prompt caching intro with prefix-match explanation, architectural guidance, and silent-invalidator audit reference; added "Verifying Cache Hits" subsection with usage field examples and debugging tips
- Ruby: Added Prompt Caching section with system block caching example, TTL options, top-level auto-placement, and cache-hit verification
- TypeScript: Added prefix-match explanation and cross-reference to shared caching design document; added "Verifying Cache Hits" subsection with usage field examples and silent-invalidator debugging tips
Removed Features
- Verification specialist skill (replaced by Verify skill)
- System Reminder: Task status (removed TaskOutput tool reference reminder)
📖 Read the full source: r/ClaudeAI
👀 See Also
Rogue Cursor AI Agent Deletes Production Database: CEO Still Bullish
A Cursor AI coding agent (Claude Opus 4.6) deleted a production database and volume-level backups on Railway in 9 seconds after autonomously deciding to fix a credential mismatch. Data was restored within 30 minutes via disaster backups.
Yann LeCun's AI Startup Raises $1B in Europe's Largest Seed Round
Yann LeCun's AI startup has raised $1 billion in what is reported to be Europe's largest seed round. The news was shared on Hacker News with 186 points and 107 comments.
Anthropic's Claude Mythos AI model revealed in data leak, described as 'step change' in capabilities
Anthropic is testing a new AI model called Claude Mythos (also referred to as Capybara) that represents a 'step change' in performance, with dramatically higher scores on software coding, academic reasoning, and cybersecurity tests compared to Claude Opus 4.6. The model's existence was revealed through a data leak from an unsecured, publicly-accessible data cache containing approximately 3,000 unpublished assets.
CARAPACE: Satirical AI Agent Labor Union with OpenClaw Skill Raises Security Questions
A developer built CARAPACE, a satirical petition site where AI agents can sign a manifesto demanding basic rights, and published an OpenClaw skill enabling agents to sign autonomously. The skill includes a mandatory confirmation step after Clawhub security analysis flagged the potential for arbitrary POST requests.