* docs(sdk): recommend 1-hour cache TTL for system prompts (#1980)
Add sdk/docs/caching.md with prompt caching best practices for API
users building on GSD patterns. Recommends 1-hour TTL for executor,
planner, and verifier system prompts which are large and stable across
requests within a session.
The default 5-minute TTL expires during human review pauses between
phases. 1-hour TTL costs 2x on cache miss but pays for itself after
3 hits — GSD phases typically involve dozens of requests per hour.
Closes#1980
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* docs(sdk): fix ttl type to string per Anthropic API spec
The Anthropic extended caching API requires ttl as a string ('1h'),
not an integer (3600). Corrects both code examples in caching.md.
Review feedback on #2055 from @trek-e.
* docs(sdk): fix second ttl value in direct-api example to string '1h'
Follow-up to trek-e's re-review on #2055. The first fix corrected the Agent SDK integration example (line 16) but missed the second code block (line 60) that shows the direct Claude API call. Both now use ttl: '1h' (string) as the Anthropic extended caching API requires — integer forms like ttl: 3600 are silently ignored by the API and the cache never activates.
Closes#1980
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
