cacheinject¶

Reformat — lossless

Places an Anthropic cache_control breakpoint at a stable prefix boundary so the provider KV cache hits across turns.

How it works¶

cacheinject places an Anthropic cache_control: {type: ephemeral} breakpoint on the last content block of the message just before the newest turn (a stable prefix boundary), so the provider KV cache hits across turns. It adds a control directive and changes no model-visible content.

The savings lever is provider-side cache hits, invisible to /stats token counts. /stats will list it under top_passthrough since it saves no content tokens — that's expected, not dead weight.

Before → After¶

before:  [ … prev turn last block ]                after:  [ … prev turn last block  {cache_control: ephemeral} ]
         [ newest turn ]                                    [ newest turn ]

Lossiness¶

None. It only attaches a cache directive; model-visible content is unchanged.

Configuration¶

No configuration.

When it shines¶

Anthropic/Bedrock/Vertex agents that don't self-cache (the savings lever is provider-side cache hits, invisible to /stats token counts).

When it's inert¶

Non-cache-aware providers, string-content messages (can't carry a block breakpoint), a breakpoint already present.