ADR 0004 Pause seam

ADR-0004 — Pause in projects, seam in the core

• Status: Accepted
• Issue: #32 (epic #26)

Context

The core ends a run at a terminal node; a follow-up is a new run in the thread. Some projects need a human to approve actions (write tools) mid-run. Added ad hoc, interrupt would conflict with spend recording while streaming, budgets and Terns.

Decision

• The core ships an explicit, optional pause seam (RunDeps.pause: checkpointer + needsApproval), off by default, and resumeAgent.
• The pause happens at the graph level (approval node), not inside the agent loop: the call is held, the agent node ends normally, then interrupt. This keeps all spend before the pause in state and in the ledger.
• Five consistency rules (ledger, budget, Tern, limits, rejection) are specified and proven with LangGraph's MemorySaver; durable checkpointers and the approval channel stay in projects.

Consequences

• Adding approval to a project is configuration, not core changes.
• The agent runs again after a decision; tools must be safe to see a stored result for an identical call (they are not executed twice).