Widens AIProvider.generate_json / generate_text / generate_text_stream
signatures to accept `system_prompt: str | list[SystemBlock]`:
- `str` (the existing call shape): passes through uncached, unchanged
behavior. Every existing caller stays on the uncached path — no silent
behavior change.
- `list[SystemBlock]`: enables Anthropic prompt caching via structured
system blocks. Caller-authored `cache_control` is honored verbatim
(policy α); if no block carries it, the provider applies
`cache_control: {"type": "ephemeral"}` to the first block only.
Gemini ignores cache_control and concatenates list entries into one
system string — the widened signature is strictly additive on that path.
Adds `anthropic.cache` structured-log telemetry: on every Anthropic
response (streaming included, via `stream.get_final_message()`), logs
`cache_read_input_tokens` and `cache_creation_input_tokens`. Telemetry
failure in streaming is swallowed so the user-facing stream never breaks.
Verification deferred: cannot run from code-server (no Python, no DB,
no dev env). TODO(phase0-verify) left inline in the module docstring.
First verification task on the new dev environment is to hit any
FlowPilot endpoint twice within 5 minutes and confirm the second call
shows cache_read_input_tokens > 0 in the `anthropic.cache` log event.
If verification fails, that's a debug task on the new env — not a
blocker for continuing Phase 0.2/0.3/0.4.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Michael Chihlas
b3be66652e