The Planning / Execution Boundary

If you remember one control from Domain 1, make it this one. The plan/execution boundary is the explicit checkpoint between an agent producing a plan and the runtime acting on the outside world. Almost every exam scenario about safety, autonomy, or guardrails routes through here.

Why the boundary exists

Without it, you cannot:

• Audit the plan before it became reality.
• Block dangerous actions cheaply (instead of cleaning them up expensively).
• Compare the agent's intent against the agent's effect — the foundation of every later evaluation.

Mantra: validate the plan, then execute. Never the other way around.

What goes on the plan side (pre-flight)

| Check | What it does | | --- | --- | | Schema validation | Does the plan conform to the typed contract? | | Policy check | Does the plan call only allow-listed tools, against allow-listed resources? | | Sandbox dry-run | Apply the plan in a throwaway environment first. | | Blast-radius estimate | What is the maximum damage if this plan misfires? | | Approval gate | For high-blast-radius actions: a human (or automated policy) signs off. |

What goes on the execution side (in-flight + post)

| Concern | Control | | --- | --- | | Tool failures | Classified retry policy, with an idempotency key. | | Partial success | Plan steps are individually committed and revertible. | | Visibility | Each tool call is logged with the trace ID from the plan. | | Drift | The runtime refuses to execute a plan that has been edited after approval. |

Decide the boundary

🎮

Choose your own outcome

+45 XP

An agent has just produced a plan to apply a database migration in production. You own the runtime. Decide how to handle the plan/execution boundary.

The plan is structured JSON and parses correctly. What do you do first?

• Execute it immediately — the agent has been reliable so far.
• Dry-run the migration in a sandboxed copy of the schema, then check blast radius.
• Ask the agent to rate its own confidence and execute if > 0.9.

Where this shows up on the exam

Several Domain 1 questions are answerable just by spotting the missing boundary. If the scenario describes an agent doing something irreversible with no pre-flight, the right answer is always "add a pre-flight validation / approval gate" — never "make the model smarter" or "trust its confidence score".