python-1.22.0

Microsoft Agent Framework has released version 1.22.0. The core framework and root package introduce Python 3.15 support, though individual packages or extras may have constraints due to upstream dependencies. A major compatibility warning is issued for persisted state containing serialized Agent Framework Content or streamed response-update records (affecting chat/message histories, session stores, protocol snapshots, and specific workflow checkpoints). Pre-1.22 runtimes cannot read records created by 1.22 with hosted or merge modes, requiring deployment isolation to prevent mixed-version access to the same store. Multiple breaking changes were introduced, including consolidating content identity, hosted execution, protocol metadata, replay, and stream-merge semantics across providers and adapters (PR 8886); enforcing fail-closed request trust boundaries and thread-ID bindings in agent-framework-ag-ui (PR 9316, 9365); preventing client Shared State or Thread Snapshots from replacing tool-approval state in agent-framework-ag-ui (PR 9368); and bounding HTTP response bodies and compressed decoding stages with configurable limits in agent-framework-declarative (PR 9358).

• Verify package and optional extra limitations before upgrading environments to Python 3.15.
• Avoid running mixed pre-1.22 and 1.22.0 workers against the same persisted storage containing serialized Content or response-update records during rolling deployments.
• Do not downgrade to pre-1.22 runtimes if version 1.22.0 has written state containing hosted or merge mode unless data is migrated or isolated.
• Review custom integrations relying on AG-UI request boundaries, tool-approval state injection, or declarative HTTP body parsing for compatibility with the new breaking constraints.