OMP-1 — Register OMP as a structured ACP provider and launch omp acp #53

Parent epic: #21
Depends on: #52
Canonical design: #20

Objective

Add the smallest viable structured OMP ACP provider on current upstream Orca infrastructure.

Target:

StructuredAgentSessionHost
  → registered agent
  → shared managed provider process
  → shared ACP client
  → omp acp

This issue establishes transport/session plumbing only. Full parity belongs to #54–#56.

Registration

Add OMP to the merged structured-agent registry with accurate:

• id/display metadata;
• launch command;
• account/config-home discovery;
• supported execution locations;
• capabilities actually available at this stage;
• provider transport identity.

Do not reuse the transcript-backed OMP profile as the structured-provider definition by accident; keep fallback and structured registration roles explicit.

Process/session lifecycle

Use the merged generic provider lifecycle:

• spawn omp acp;
• initialize ACP;
• authenticate via supported method;
• create a new session;
• load/resume an existing compatible session;
• close through the shared proven-exit path.

No direct omp --mode rpc or custom JSONL transport.

Minimal timeline

Prove one complete structured turn:

• user prompt;
• assistant text;
• turn completion;
• journal write;
• clean close.

Keep unsupported capabilities undeclared until later issues wire them.

Compatibility gate

Detect/handle OMP versions that do not expose the required ACP server.

Until #57, unsupported versions/environments must remain eligible for the existing terminal/transcript Native Chat path.

Tests

• create support;
• registered-agent lookup;
• process start/readiness;
• new session;
• load/resume;
• prompt/text/complete;
• child exit;
• unsupported ACP version/command fallback;
• no duplicate Agent Dashboard/session identity.

Acceptance criteria

• OMP runs through Orca's shared ACP client.
• One complete structured turn works through the real host.
• Session identity can be created and resumed.
• Process ownership is entirely the shared managed-provider lifecycle.
• Unsupported ACP cases do not break existing OMP Chat.
• No direct OMP RPC transport is added.