The fak caching ladder
What this is. The same subject — how fak caches so a long, stop-start agent session stays cheap — written five times, once for each kind of reader. Each rung is pitched at both a human audience and a model/agent capability tier: a newcomer or a small 8B agent is served at Level 1; a frontier /
fable-tier reader is served at Level 5. Pick your rung, or climb the whole ladder.
Caching in fak spans two very different layers — the provider’s prompt cache that fak steers on the API wire, and the kernel-owned KV cache fak owns when it runs the model itself. A single flat page either loses the beginner or bores the expert. This ladder splits the difference: each rung assumes exactly what the one below it taught.
The five rungs
| Level | Who it’s for | What you’ll get |
|---|---|---|
| 1 · What is caching? | A newcomer, or a small/8B agent that needs the one-screen version. No jargon. | What a prompt cache is, why it matters, what to type, how to tell it helped. |
| 2 · Managed cache in practice | A competent dev or mid-tier agent running fak manage -- claude. |
--managed-cache on\|off\|auto, the defaults, Pro/Max headroom, how to verify. |
| 3 · Cache economics & the wire | A senior engineer / capable agent who wants the mechanism and the money. | Sliding window vs 1h tier, the read/write multipliers, byte-exact prefix, provider matrix. |
| 4 · The kernel-owned KV cache | A platform engineer / strong agent running the model in-kernel. | Addressable KV cache, bit-exact span eviction, prefix cloning, WITNESSED vs OBSERVED accounting. |
| 5 · The caching frontier | A fable-tier reader / researcher who wants the SOTA and the open problems. |
vCache enablement, SOTA optimizations, cross-provider futures, the honest open edges. |
How to read it
- Just want it to work? Read Level 1, then Level 2, and stop. That’s the whole user-facing story.
- Operating a fleet / paying the bill? Level 3 is where the economics live.
- Running the model yourself? Level 4 is the kernel layer; Level 5 is where it’s going.
Each rung ends with a nav footer linking its neighbours and back here.
See also
- What is fak’s managed cache? — the original plain-English managed-cache page; Level 2 is its canonical successor.
- Addressable KV cache · KV cache for agentic context — the kernel-owned layer Level 4 builds on.
- The fak/DOS glossary — one-line definitions of the vocabulary.