Add an exact generation-fenced recreate operation for one live task

[myobie]

Problem

Operators need a deliberate way to recreate one exact live managed task from its current compiled Agent Spec without deleting its workspace or durable st2 state. Neither host-wide st2 down nor backend-level pty restart expresses that boundary: a raw restart may replay an older persisted process contract instead of the current declaration.

The operation is generic. Core st2 does not choose a harness-specific fresh or resume method. Axe and its harness driver compile that decision into the declaration under #124 before st2 is asked to recreate the task.

Proposed command shape

Non-normative:

st2 task recreate \
  --task <exact-task-id> \
  --expect-runtime <runtime-generation> \
  --expect-desired <launch-generation>

Required contract

• Select one exact canonical task under an explicit catalog, host, effective runtime root, bus identity, runtime incarnation, and desired launch generation.
• Re-read the declaration and recheck both fences immediately before disruption.
• A stale runtime, changed or retired declaration, wrong root, target disappearance, or ambiguous backend state fails closed without touching the live process.
• Capture an immutable effective launch contract and persist a bounded operation record before stopping the task.
• Stop and reap only the fenced runtime incarnation.
• Launch the captured compiled contract exactly once and persist a terminal receipt containing the prior runtime, desired generation, stop result, launch result, and resulting runtime/Run ID.
• If st2 stops after teardown or launch, ordinary reconciliation resumes the same recorded operation rather than adopting an intervening declaration or replacing a successor again.
• Preserve workspace files and the durable bus/state anchor: inbox, archive, context, decisions, linked resources, status path, and declaration.
• Reconcile derived tasks, including DING companions, with the canonical task without duplicates or leaks.
• Do not infer recreation from command drift, generation drift, catalog edits, compaction, crash, or supervisor restart. Drift remains observational until this explicit operation is authorized.
• Emit a machine-readable terminal result distinguishing replaced, target-not-live, fence-conflict, retired-or-changed, backend-unknown, stop-failed, and launch-failed.

Acceptance

• A matching request changes the runtime incarnation exactly once and launches the captured compiled contract.
• An unrelated task keeps its PID and runtime generation.
• Workspace and every durable resource byte survive unchanged.
• Stale runtime, changed desired generation, retired declaration, wrong root, missing/dead target, and backend-error controls fail closed.
• A crash before the durable stop phase leaves the original process untouched.
• A crash after teardown resumes the recorded operation without selecting newer unrelated bytes or launching duplicates.
• A crash after launch does not replace the successor a second time.
• Provider-specific prompt construction and session selection remain outside core lifecycle code.

Relationships

• Expose desired versus observed launch generation for adopted tasks #40 supplies desired-versus-observed launch generations and drift visibility.
• Define renderer-owned harness sessions and the generic st2 lifecycle boundary #124 supplies the renderer-owned session decision already compiled into the task contract.
• Model Agent Run identity in task inventory #145 supplies Agent Run identity for the resulting launch.
• Activation: deploy PTY environment persistence for manual restart #30 covers backend activation for persisted managed environment replay.
• Decide ownership of stable agent identity at PTY creation #64 owns stable task identity at PTY creation; recreation preserves that identity.