AHP Spec v0.6.0

[0.6.0] — 2026-07-20

Spec version: 0.6.0

Added

• Changeset.capabilities with a review presence flag (ChangesetCapabilities) so a changeset can advertise support for the per-file review workflow up-front on the session's changeset list. (#328)
• Optional _meta slot on SystemNotificationResponsePart, following the MCP _meta convention. A host MAY attach a machine-readable descriptor of what triggered the notification so clients can categorize, icon, group, filter, or localize it without parsing content. (#308)
• chat/turnStarted carries a startedAt timestamp, chat/turnComplete/chat/turnCancelled/chat/error carry an elapsed duration (milliseconds, producer's own clock), and completed turns expose their start time and duration.
• Asynchronous tool-call risk assessments with a model-provided explanation and normalized safety score.
• ToolCallStatus.AuthRequired tool call state and chat/toolCallAuthRequired / chat/toolCallAuthResolved actions so a running MCP-contributed tool call can pause mid-execution on an OAuth challenge (McpAuthRequirement) and resume once the client authenticates; surfaced at the session level via a new toolAuthentication SessionInputRequest variant, and AuthenticateParams gained an optional scopes field and now accepts resources discovered from a live McpServerAuthRequiredState or ToolCallAuthRequiredState in addition to AgentInfo.protectedResources. chat/toolCallComplete now also accepts a failed result while a tool call is auth-required, letting a client cancel that invocation without completing the authentication challenge.
• McpAuthRequirement.oauthClient metadata for pre-registered public and confidential OAuth clients.

Changed

• Renamed the changeset review action changeset/filesReviewedChanged to changeset/filesReviewChanged (field fileIds → files) and made it client-dispatchable, so a reviewer can toggle a file's reviewed flag directly through the write-ahead reducer. (#328)
• Input requests now live in turn responseParts, with an optional response until chat/inputCompleted submits the result. (#327)