observability.md: "Why two tiers" claimed the harness currently writes an
upstream token into the agent's own claude settings; that path was removed
with the direct-export mode it served (nix/agent-modules/otel.nix:56-63).
Reworded as the hypothetical the paragraph is actually making.
gateway.md: restored the agent-trust pointer to
/run/hive-ca/trust-bundle.pem in "Cert prompts" (hive-ca-trust.nix:41),
dropped by the earlier rewrite. Corrected the SPA-fallback section: only
the chat.<swarm> vhost uses the Accept-header map
(hive-matrix.nix:693-696); per-agent split mode uses file-existence
try_files (gateway_nginx.rs:93-134), not the same mechanism.
Refs #3902