refactor(planning): remove the original decision trace

docs/adr/0006-user-selected-horizons-and-cancellable-calculations.md

@@ -1,17 +1,19 @@
 # User-Selected Horizons and Cancellable Calculations
 
-Accepted for [issue #12](https://gitea.nessar.fr/nessar/vac-optimizer/issues/12). Fixed, saved planning horizons are implemented by [issue #57](https://gitea.nessar.fr/nessar/vac-optimizer/issues/57); user cancellation with a retained valid plan and original trace is implemented by [issue #58](https://gitea.nessar.fr/nessar/vac-optimizer/issues/58); removal of the automatic calculation deadline and heartbeat-based worker liveness are implemented by [issue #59](https://gitea.nessar.fr/nessar/vac-optimizer/issues/59). The indicative duration estimate is implemented by [issue #60](https://gitea.nessar.fr/nessar/vac-optimizer/issues/60); its initial model, session-local refinement and calendar-rendering measurement are documented in [planning-duration.md](../planning-duration.md).
+Accepted for [issue #12](https://gitea.nessar.fr/nessar/vac-optimizer/issues/12). Fixed, saved planning horizons are implemented by [issue #57](https://gitea.nessar.fr/nessar/vac-optimizer/issues/57); user cancellation with a retained valid plan is implemented by [issue #58](https://gitea.nessar.fr/nessar/vac-optimizer/issues/58); removal of the automatic calculation deadline and heartbeat-based worker liveness are implemented by [issue #59](https://gitea.nessar.fr/nessar/vac-optimizer/issues/59). The indicative duration estimate is implemented by [issue #60](https://gitea.nessar.fr/nessar/vac-optimizer/issues/60); its initial model, session-local refinement and calendar-rendering measurement are documented in [planning-duration.md](../planning-duration.md).
 
-`deadlineMs` remains an opt-in contract for technical callers: a finite non-negative planning-work budget with no ten-second cap. An omitted value is unlimited. It starts after calendar preparation and excludes trace capture, observer callbacks, and post-outcome artifact work. The calendar and benchmark omit it. A one-second worker heartbeat renews the coordinator's thirty-second inactivity timer during cooperative preparation and search; total elapsed time never triggers that timer while activity continues. Worker errors and unavailable execution retain their explicit outcomes, and monitoring ends when the outcome arrives so delayed trace delivery cannot invalidate it.
+`deadlineMs` remains an opt-in contract for technical callers: a finite non-negative planning-work budget with no ten-second cap. An omitted value is unlimited. It starts after calendar preparation and excludes observer callbacks and post-outcome explanation work. The calendar and benchmark omit it. A one-second worker heartbeat renews the coordinator's thirty-second inactivity timer during cooperative preparation and search; total elapsed time never triggers that timer while activity continues. Worker errors and unavailable execution retain their explicit outcomes, and monitoring ends when the outcome arrives so delayed explanation delivery cannot invalidate it.
 
-VacOptimizer accepts explicitly selected, fixed planning horizons whose start may be past and whose duration may exceed twelve months, retaining today through the same date twelve months later as the default. Calculations remain in the browser and run to completion without an automatic elapsed-time cutoff, with an indicative duration estimate and an explicit Cancel action; this accepts variable waiting time and resource use to make longer horizons usable without silently changing the user's dates. This supersedes ADR 0003's ten-second automatic planning limit and its retention in both ADR 0004 documents, while preserving the separation between the planning outcome, stable explanation, and original trace.
+VacOptimizer accepts explicitly selected, fixed planning horizons whose start may be past and whose duration may exceed twelve months, retaining today through the same date twelve months later as the default. Calculations remain in the browser and run to completion without an automatic elapsed-time cutoff, with an indicative duration estimate and an explicit Cancel action; this accepts variable waiting time and resource use to make longer horizons usable without silently changing the user's dates. This supersedes ADR 0003's ten-second automatic planning limit and its retention in both ADR 0004 documents, while preserving the separation between the planning outcome and stable explanation.
 
 The planning-period control in Configure your leave uses an inclusive last planning date. The planner retains its half-open horizon by using the following calendar date as its exclusive end, matching the inclusive date-selection convention of TIME_WINDOW rules.
 
 Editing the horizon does not trigger a calculation. The user can adjust dates, balances, and rules before using the existing Calculate action; until a new calculation is requested, the displayed calendar retains its preceding outcome and horizon.
 
-A successful calculation displays the calendar once, as soon as the full planning objective order is complete, without displaying intermediate plans during optimization. Trace delivery continues in the background and never delays or changes that final calendar. The indicative duration estimate covers elapsed time until the final calendar is usable, including any trace capture that delays the outcome, rather than the additional time to deliver the complete trace.
+A successful calculation displays the calendar once, as soon as the full planning objective order is complete, without displaying intermediate plans during optimization. Stable explanation delivery follows the outcome and never changes that final calendar. The indicative duration estimate covers elapsed time until the final calendar is usable, excluding later explanation work.
 
 Before Calculate, the estimate is shown as an approximate range in seconds or minutes based on the horizon, balances, and rules. It starts with a rough estimate and is refined using measured calculation durations on the same device; it never becomes an automatic stopping deadline.
 
 User cancellation during optimization preserves the best valid plan already found and labels it as a cancelled, incomplete calculation. Before any valid plan exists, cancellation reports that the calculation was cancelled without presenting a plan or claiming an obligation conflict.
+
+Issue #76 supersedes all original-trace requirements in this ADR and both ADR 0004 documents. Decision capture, historical analysis and replay are removed. Immutable calculation, valid-incumbent and final-state snapshots remain for the retained explanation, cancellation recovery and displayed-placement counterfactuals. Cancellation still preserves the best available jointly valid plan and never implies an obligation conflict.