refactor(planning): remove the original decision trace

docs/adr/0004-stable-explanation-original-trace-counterfactual.md

@@ -1,11 +1,9 @@
-# Stable Explanation, Original Trace, and Counterfactuals
+# Stable Explanation and Displayed-Placement Counterfactuals
 
-The automatic planning deadline referenced below is superseded by [ADR 0006](0006-user-selected-horizons-and-cancellable-calculations.md), implemented by issue #59. Technical callers can still opt into an explicit planning-work budget; the user flow has no automatic cutoff.
+Issue #76 supersedes the original decision-trace and historical-counterfactual requirements of this ADR. Calculations no longer capture, retain or deliver decision history, and the UI has no trace explorer, replay, historical candidate statuses or balance-attempt lists.
 
-VacOptimizer exposes one client-side calculation context. Its immutable submitted snapshot and planning outcome are independent from three explanation concerns:
+VacOptimizer exposes one client-side calculation context with an immutable submitted configuration. Its outcome is independent from the stable explanation, which describes the final displayed plan and remains useful for complete and valid incumbent plans.
 
-- the stable plan explanation is derived from the final displayed plan and remains useful for complete or incumbent plans;
-- the calculation trace is captured while the producing run executes, grouped by phase and atomic decision, and may become ready after the outcome;
-- counterfactual date analysis is an explicitly hypothetical operation that removes only the selected final placement, or starts from a selected trace decision's exact pre-decision state, and never rewrites the plan or historical trace.
+Counterfactual date analysis tests a displayed placement over every date of the submitted half-open horizon. It uses the captured configuration and final-state snapshot, releases only that placement, preserves its entitlement, leave type and rule provenance, and fixes unrelated placements. Earned-entitlement chronology and all obligations still apply. The result is explicitly hypothetical and never mutates the displayed plan. Historical decisions are not selectable analysis baselines.
 
-The public planning outcome is delivered as soon as planning work finishes. Trace capture and delivery have separate readiness/failure state, remain local to the latest calculation, and cannot turn a valid outcome into an explanation error. Counterfactual work is cancellable or ignored when its calculation identity is stale. The existing deterministic constraint-first planner and its planning-work deadline remain unchanged.
+The public outcome is delivered as soon as planning work finishes. Explanation delivery failures cannot replace it. Counterfactual work is cancelled or ignored when its calculation identity is stale. Search breadth, allocation previews, user priorities, deterministic selection and ADR 0006's cancellation, liveness and technical-budget contracts remain unchanged. Workers finish after required outcome and explanation delivery without acknowledgement queues.