Prove the shipped adversarial-planning document logic

[taras]

Story

As a workflow author, I want InstructionFiles, Discovery, UserCheckpoint, and Planning to execute against shipped components, so orchestration starts from proven document logic.

Scope

Use stub Agents and document-supplied Answers in one process and one contextual working directory. Do not require WorkflowRun persistence, Repository/Worktree, Git, forge, or Worker Shell effects.

Exercise the current target documents from PR #181 after #292 has synchronized the relevant document logic. The PR does not need to merge before this proof; the proof is evidence required to merge it.

The documents use the namespaced props contract from #305. Do not build this proof against the bare-prop behavior that #305 removes.

Acceptance

• Exact instruction paths and contents reach every relevant prompt.
• Malformed Agent JSON receives only the bounded correction attempts shown in the documents.
• A failed planner verdict returns a prescriptive revision prompt to the same implementor conversation.
• Material choices reach UserCheckpoint and cannot become implicit approval.
• A passing verdict exits the planning loop.
• Taras settles exhaustion behavior before implementation; the implementor does not choose it.
• Tests discriminate every claimed branch and ordering.

Dependencies

• Synchronize the #181 living target with settled XMD contracts #292 must first synchronize the document sections under test; PR Document adversarial implementation workflow WIP #181 remains open while the proof is integrated.
• Namespace Markdown props under the props binding #305 supplies namespaced props.
• End goal: Document adversarial implementation workflow WIP #181.