Capability-gated protocol probes and SEP-2164 unknown-resource checks (139 checks total): tool-only protocol probes skip when capabilities.tools is absent instead of passing on -32601 (ADR-0002), stateless 2026-07-28 first contact selects a declared list RPC, and protocol.unknown_resource verifies -32602 with error.data.uri on missing resources.
SEP-2549 cache hints across tools, resources, and prompts: catalog.cache_hints inspects tools/list, resources/list, and prompts/list via Client.ListResourcesWithHints and Client.ListPromptsWithHints, validating ttlMs >= 0 and cacheScope in {"public", "private"} on declared endpoints.
Immediate RFC 6761 .invalid egress refusal and conformance guide: internal/egress answers 502 Bad Gateway before DNS lookup on .invalid hosts so stub resolvers cannot stall fault-injection runs, and docs/migrating/from-mcp-conformance.md plus docs/COMPARISON.md document how passmcp pairs with @modelcontextprotocol/conformance.
In lockstep with the passmcp family at 0.0.9: requires satellion.com/passmcp-reportingv0.0.9, updates go.yaml.in/yaml/v3 (v3.0.6) and github.com/spf13/pflag (v1.1.0) in SBOM.md, and floors certifi in the manual build lock.