Two independent bugs evicted the cached gateway AIAgent on every turn,
preventing the prompt cache from ever warming:
1. Model normalization mismatch: the post-run fallback-eviction check
compared _agent.model (stripped in AIAgent.__init__) against the raw
_resolve_gateway_model() config string. For vendor-prefixed config on
native providers (e.g. 'deepseek/deepseek-v4-pro' vs 'deepseek-v4-pro')
this was always unequal, so the agent was evicted after every
successful run. Normalize _cfg_model the same way (skip aggregators).
2. Discord triggering message_id leaked into the cached system prompt via
build_session_context_prompt()'s Discord IDs block. message_id changes
every turn, so the agent-cache signature (computed from the ephemeral
prompt) changed every Discord turn -> rebuild every message. The id is
now injected per-turn into the user message (where per-turn content
belongs and does not touch the cache signature); the cached IDs block
carries a static pointer to it, preserving reply/react/pin via the
discord tools.
Adapted from #28846. Bug #1 fix is the contributor's; bug #2 reworked to
be non-destructive (keeps the triggering-id capability instead of deleting
it). Redundant auto-reset eviction (already on main via #9893/#48031) and
the wrong-premise reset_context_note plumbing from the original PR were
dropped.
Co-authored-by: Hermes Agent <hermes@nousresearch.com>
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