Candidate tiers show current hook coverage. Platinum is the high-assurance target being implemented through the reference agentic runtime and conformance work.
A current audit of which hook surfaces each major agent runtime exposes. Candidate tiers show the as-is Bronze/Silver/Gold coverage available today. Platinum is the to-be high-assurance profile and is not used to score current publishers yet.
HookBus Agent is being built as the open-source reference runtime for governance-native AgentHook execution. It is not required for conformance; it is a proof object for the high-assurance profile.
Audit method: direct inspection of each runtime's published hook surface and public Agentic Thinking publisher repositories as of 19 May 2026. Gold candidate and Silver candidate mean the runtime currently exposes enough hooks for that as-is v0.2 coverage profile. Platinum means the future high-assurance target after the relevant AHP drafts and conformance test harness are accepted. Runtime providers may self-attest by Pull Request to the AgentHook repository. Self-attested rows will be marked accordingly. This audit is for technical interoperability comparison, not procurement guidance. Next scheduled review: 2 June 2026, then fortnightly while publisher coverage is changing.
Pending rows will be filled as each runtime's hook surface is reviewed and validated against the conformance test suite. Self-attested rows and test harness verified rows will be marked accordingly. Microsoft Agent Governance Toolkit is tracked as a control/subscriber layer, not as an agent runtime publisher.