Revisit the API server and Task lifecycle

[rakyll]

As AX evolves alongside Agent Substrate, we need to revisit the mechanics of the API server (ax-server). This issue tracks foundational changes to align the Task lifecycle directly with Substrate actors, transition from queue-driven orchestration to direct RPC-driven execution, Postgres storage, and support custom OCI container images as tasks.

Changes

1. Task-to-Actor Lifecycle Alignment

Once the Agent Substrate's new actor lifecycle is established, AX's task model should map strictly 1:1 to Substrate actors:

• Lifecycle Parity: All task lifecycle states and operations must directly mirror Substrate actor lifecycle events: creation, suspension, resumption, tagging, reverting and other additional capabilities. Eliminate reconciliation mismatches or intermediate states that duplicate or lag behind the underlying Substrate actor state.
• Golden images: Align on the golden image decisions, AX doesn't need golden images.
• ActorTemplate Revisit: The use and role of ActorTemplate in AX will be revisited based on upstream design decisions in Agent Substrate.
• Resources, sandboxing config: Allow users to configure tasks to leverage everything Agent Substrate offers per actor. Discuss the best way how we can avoid the bifurcation of the APIs.

2. RPC-Driven Control Plane

• Transition away from asynchronous work queues / event loops as the execution mechanism for lifecycle operations.
• RPCs become the driving factor: Task operations (create, suspend, resume, delete, revert) should execute and reconcile synchronously via direct RPC invocations to the control plane and Substrate.
• ax apply <manifest>: Kept as a first-class CLI command for human ergonomics, scripting, and declarative local workflows.

3. Storage

• Migrate persistence and state storage from Redis to PostgreSQL.
• Retire and remove Redis support entirely (both for state storage and coordination).
• Define relational schemas and migrations for Tasks, Workspaces, and Models, and ensure we establish transition tools.

4. Runner Injection

• Runner Injection: The AX runner binary/tooling will be injected into the actor at runtime rather than requiring a specialized base image.
• Arbitrary OCI Images: Users will be able to specify any standard OCI container image in their task specification, enabling arbitrary language runtimes, OS distributions, and user-supplied environments.