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
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