Prompt caching — researched
Prompt caching lets the API reuse an already-processed prompt prefix (tools → system → messages) across requests to cut cost and latency: Anthropic offers automatic caching or explicit `cache_control: {"type": "ephemeral"}` breakpoints with 5-minute or 1-hour TTLs, bills cache writes at 1.25×/2× and cache hits at 0.1× the base input price, and reports them in usage.cache_creation_input_tokens / cache_read_input_tokens; OpenRouter passes cache_control through to Anthropic and Gemini, adds provider sticky routing, and documents OpenAI automatic caching. Two of the three docsets contributed (the OpenAI export is empty).
Related concepts
- cache_control — is a part of Prompt caching; Anthropic/OpenRouter per-block cache marker
- cache breakpoint — is a part of Prompt caching
- cache hit — is a measure of Prompt caching
- cache pricing — is a measure of Prompt caching; pricing multipliers and table columns; MTok alone is any price table
- prefix hierarchy — is a part of Prompt caching; tools → system → messages; a change at one level invalidates it and everything after
- cache write — is a measure of Prompt caching
- Message Batches — is a related of Prompt caching; features whose interaction with the prompt cache the docs describe; never qualifies a unit alone
- cache diagnostics — is a part of Prompt caching; Anthropic beta that reports why a cache missed
- automatic caching — is a hyponym of Prompt caching; provider places the cache point (Anthropic auto mode, OpenAI, Gemini implicit)
- cache TTL — is a measure of Prompt caching
- cache invalidation — is a problem of Prompt caching; what changes cause the prefix to stop matching
- cache prefix — is a part of Prompt caching; the cache key is the exact request prefix: tools → system → messages
- cache_read_input_tokens — is a measure of Prompt caching; usage/pricing fields reported per response
- cacheable — is a variant of Prompt caching; the docs' adjective for content the prompt cache can hold
- cache read — is a measure of Prompt caching
- explicit caching — is a hyponym of Prompt caching; caller places cache_control breakpoints
- cache pre-warming — is a dependent of Prompt caching; loading the cache before real traffic
- sticky routing — is a dependent of Prompt caching; OpenRouter: routing follow-up requests to the provider holding the cache
- ephemeral cache_control type — is a instance of Prompt caching; the only cache_control type; bare 'ephemeral' excluded (containers)
- minimum cacheable prompt length — is a measure of Prompt caching; per-model token floors below which nothing is cached