feat(readme): document provider prompt caching behavior and SmartAI cache integration

changelog.md

@@ -7,6 +7,12 @@
 
 
 
+### Features
+
+- document provider prompt caching behavior and SmartAI cache integration (readme)
+  - Adds provider prompt caching to the feature list in the README
+  - Clarifies that provider-specific cache metadata is centralized in @push.rocks/smartai
+
 ## 2026-05-15 - 3.5.0
 
 ### Features

readme.md

@@ -76,6 +76,7 @@ console.log(result.usage);   // { inputTokens, outputTokens, totalTokens, cacheR
 - ⚡ **Parallel tool execution** — multiple tool calls in a single step are executed concurrently
 - 🔧 **Auto-retry with backoff** — handles 429/529/503 errors with header-aware retry delays
 - 🩹 **Tool call repair** — case-insensitive name matching + invalid tool sink prevents crashes
+- 💰 **Provider prompt caching** — uses SmartAI cache helpers for Anthropic breakpoints and OpenAI cache affinity
 - 📊 **Token and reasoning streaming** — `onToken`, `onReasoning*`, and `onToolCall` callbacks for real-time progress
 - 💥 **Context overflow handling** — detects overflow and invokes your `onContextOverflow` callback
 
@@ -168,6 +169,7 @@ const saved = result.toolCalls.some((call) =>
 
 SmartAgent enables prompt-cache defaults by default:
 
+- Cache behavior is provided by `@push.rocks/smartai`, so provider-specific cache metadata stays centralized there.
 - Anthropic-compatible models get cache breakpoints on the first two system messages and the two most recent non-system messages.
 - OpenAI models get `store: false` by default and, when `sessionId` is provided, `promptCacheKey: sessionId` with `promptCacheRetention: 'in_memory'`.
 - Longer retention is opt-in. Use `cache: { retention: '24h' }` for OpenAI or `cache: { retention: '1h' }` for Anthropic.