# Protocol v3 operational addendum: checkpoint continuation

Registered 27 September 2026, before any continuation from a timed-out or
otherwise incomplete v3 solver invocation.

## Why this addendum exists

The preregistered v3 solver cases remain the same: N=30/32/36/44; OpenFOAM
2512 `simpleFoam`/steady SIMPLE; Open MPI 4.1.6; eight Scotch ranks; original
uniform time-zero fields; fixed end iteration 6,000; original residual, force
plateau, and y+ gates. The 5,400-second limit is an execution limit for one
launcher invocation, not a scientific stopping criterion. An invocation that
reaches its wall-clock limit before iteration 6,000 is incomplete and fails
acceptance until continued and evaluated to the registered end iteration.

If needed, continue from the latest fully written parallel checkpoint using
`startFrom latestTime`. Keep `endTime 6000`, mesh, fields, numerical schemes,
models, boundary conditions, function objects, relaxation, decomposition,
and all solver tolerances unchanged. Do not reset any field to time zero or
select/relabel a different starting field. Record each solver-log segment,
its start and last logged iteration, exit status when known, `End` marker,
and SHA-256. The final export must include all segments. A final segment must
contain the completion marker at iteration 6,000 for acceptance.

The continuation only resumes the same deterministic steady iteration from a
checkpoint; it does not change the registered numerical experiment or any
acceptance gate. Any solver/input change requires a separately preregistered
protocol and a fresh candidate case. No segment boundary is itself evidence of
convergence. Residual checks still require every equation on every iteration
5,901–6,000, force checks use the final 100 samples, and y+ must be sampled at
6,000. Richardson/GCI remains withheld unless the final accepted outputs also
meet the v3 monotonicity and asymptotic-range review.

OpenFOAM's documentation defines `startFrom latestTime` as selecting the most
recent available time directory; see the [OpenFOAM user guide: time and data
input/output control](https://www.openfoam.com/documentation/user-guide/6-solving/6.1-time-and-data-inputoutput-control).