* Studio: support Anthropic 1h cache TTL via prompt_cache_ttl field
Anthropic exposes two ephemeral cache pools per request: the default
5-minute pool, and a 1-hour pool selected by attaching `ttl:"1h"` to
the `cache_control` marker. 1h writes are billed at 2x base input vs
1.25x for 5m, but reads stay at 0.1x for both, so a single extra read
landing more than 5 minutes after the write pays off the premium.
Studio hardcoded the 5m pool via `cache_control: {type:"ephemeral"}`
on both breakpoints. For chats with multi-minute idle gaps (people
juggling tabs, long-running tool calls between turns), the cache
expires before the next turn and every read becomes a cache_creation,
not a cache_read -- exactly the case where the 1h pool wins.
Changes:
- Add `prompt_cache_ttl: Optional[Literal["5m", "1h"]]` to
ChatCompletionRequest. Default (None) preserves today's 5m behavior.
- Thread through `routes/inference.py` ->
`stream_chat_completion` -> `_stream_anthropic`.
- Build a shared `cache_marker` dict in `_stream_anthropic`; attach
`ttl` only when the request asks for one of the two valid values.
Unknown TTL strings are silently dropped to avoid sending malformed
markers (the upstream API would 400).
- Apply the same marker to both existing breakpoints (system block at
line 1175 and the latest-message tail at line 1198 / 1213) so the
pool selection is consistent across the whole prefix.
- Add `test_anthropic_cache_ttl.py` with 11 parametrized cases
pinning the outbound body shape: omitted -> default marker;
explicit `5m`/`1h` -> ttl field set; unknown values dropped;
caching off -> no markers at all.
Verified upstream that `cache_control: {type:"ephemeral", ttl:"1h"}`
is accepted by the Anthropic API today; no beta header required.
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* Relax prompt_cache_ttl to Optional[str] (Codex P1)
Declaring `prompt_cache_ttl` as `Optional[Literal["5m", "1h"]]` made
FastAPI/Pydantic 422 the request before _stream_anthropic could even
see the field. The whole point of the downstream drop-unknown-values
behaviour was to keep a stale frontend from crashing the request;
the strict Literal at the request layer defeated that.
Loosen the schema to Optional[str]; the existing in-helper guard
already restricts forwarded values to {"5m", "1h"} (everything else
is silently dropped). Test suite stays unchanged -- the bogus-value
cases in test_anthropic_cache_ttl.py already pass arbitrary strings
through and assert they are dropped before the wire.
* Address review: confirm extended-cache-ttl beta header is GA
Reviewer asked whether the 1h cache TTL still requires the
`extended-cache-ttl-2025-04-11` anthropic-beta header. Investigated:
- Live-tested api.anthropic.com on claude-opus-4-7 (2026-05-22)
with cache_control={type:"ephemeral", ttl:"1h"} and NO beta
header. Got status 200 and ephemeral_1h_input_tokens populated
on the create turn, plus cache_read_input_tokens populated on
the reuse turn.
- Cross-checked the current prompt-caching docs: no mention of
any beta header on the 1h TTL path.
Conclusion: the gate has been promoted to GA. The code already
does not send the beta header (the cache_marker dict only carries
`type`/`ttl`), so no wire change is needed. Pinned the contract
with two regression tests that assert the header is NOT on the
outbound request, and added a docstring note explaining the
investigation outcome so a future reader does not re-add it.
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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