55dfb517e4
Address review feedback on #39130: the new sessionAiPeerPrefix setting affects the resolved Honcho session key, which HonchoMemoryProvider freezes at construction (self._session_key). Because it wasn't part of the gateway's cached-agent signature, a live config flip left an existing gateway session bound to its old, AI-peer-agnostic Honcho session until an unrelated eviction or restart. Add honcho.session_ai_peer_prefix to _HONCHO_CACHE_BUSTING_KEYS and the _extract_honcho_cache_busting_config values so a flip rebuilds the cached agent on the next turn, mirroring the existing aiPeer / pin_peer_name / runtime_peer_prefix contracts. Also close the symmetric gap for the pre-existing user-side sessionPeerPrefix: it feeds the same resolve_session_name output (per-session/title/per-repo/ per-directory strategies) into the same frozen _session_key, so it had the identical live-flip staleness bug and was likewise absent from the cache signature. Fixing both keeps the two prefixes consistent. Add one config-flip regression test covering both keys, alongside the existing Honcho cache-signature test.