Caveman/Ponytail injection now matches each target wire format instead of
assuming an OpenAI-shaped body:
- Chat arrays append a text block; Responses arrays append input_text and
create typed message items
- Claude inserts before the final cache-control block; Gemini preserves the
snake/camel systemInstruction wrapper
- Kiro updates systemPrompt and its mirrored first-user prefix atomically,
rolling back if the pair fails to converge
- Format label decides Claude/Gemini before the wire-shape sniff, since their
bodies also carry messages[]/contents[] and Anthropic rejects a "system"
role inside messages[]
- Delimiter-aware dedup makes injection exact-idempotent across retries, so
distinct prompts sharing a long prefix are no longer collapsed
- Every write is fail-open on frozen or proxied bodies
Saver order and X-9Router-Token-Saver: off behavior are unchanged.
Fixes#3202.
cadef6c4ff