v4.6.4 spec/v0.9.0
onyx-dot-app/onyxAug 28, 2026 → Aug 28, 20261 day between releases
What's New
The newer tag is a spec-only release (AHP 0.9.0) with breaking protocol changes, not a successor to the v4.6.4 app build.
Breaking Changes
- The `error` field is removed from `changeset/contentChanged`; changeset failures must now be read from `changeset/statusChanged`.
- Session-level forking is removed from `createSession`, so callers must fork at the chat level instead.
- `ContentNotFound` is no longer an exported AHP error code, and code `-32006` is reserved but unassigned.
- The failed session lifecycle value `creationFailed` is renamed to `failed`, and `TerminalSessionClaim` now requires the owning chat URI.
- `SessionToolClientExecutionRequest.toolCall` is narrowed to a running tool-call state, and annotations now require a session URI in `origin`.
New Features
- Automation catalogue and automation-run channels enable host-defined triggers and automation-origin messages for shared agent session workflows.
- Turn errors are now durable response parts, and resumable errors can reopen the same turn via `chat/turnResume`.
- `InitializeResult._meta` lets hosts advertise implementation-specific extension capabilities during initialization.
Improvements
- Terminal state now uses an explicit `running`/`exited` lifecycle that preserves exits lacking an exit code.
- Generated clients preserve unknown values for nonexhaustive protocol enums and their discriminated unions, improving forward compatibility.
- Automation catalogue snapshots now use `AutomationState.entries` with items named `AutomationEntry`.
Bug Fixes
- Changeset failures are now surfaced through the status-change channel rather than as an error payload, correcting the failure signalling model.
Upgrade Notes
These two tags belong to different release streams (application build vs. protocol specification), so v4.6.4 to spec/v0.9.0 is not a normal in-place upgrade — confirm which artifact you actually pin. Consumers of the spec must regenerate clients and migrate off `changeset/contentChanged.error`, session-level forking, `creationFailed`, and the exported `ContentNotFound` code. The v4.6.4 warning about running the OpenSearch document index migration before upgrading still applies to the application track.
The Two Releases
v4.6.4
Aug 28, 2026· 2 months ago
A maintenance release addressing UI cursor issues, docx preview readability in dark mode, and MCP tool storage logic.
Full release notesAHP Spec v0.9.0
Aug 28, 2026· 2 months ago
Defines the AHP 0.9.0 specification, establishing the protocol for automation catalogues, durable errors, and session lifecycle management.
Full release notes