Stills: --stills-window-sigmas sets the prediction window's half-width

The stills prediction window was a fixed two run rocking widths. --stills-window-sigmas K predicts,
integrates and (with --export-observations) exports the rocking curve's tails out to K widths, which
is what a partiality model fitted from the data needs to see; --min-partiality decides separately
what the merge takes. The default stays 2 and the processing is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HVeDQqN9qRD57vnShzTC37

rugnux/Rugnux.h

@@ -268,6 +268,10 @@ struct ProcessConfig {
     // (ObservationMtzTable; --export-observations). Off by default; it does not change the processing.
     bool export_observations = false;
 
+    // Stills: the prediction window's half-width, in run rocking widths (--stills-window-sigmas). Wider
+    // predicts, integrates and exports more of the rocking curve's tails.
+    double stills_window_sigmas = 2.0;
+
     // If set, after merging, validate the merged intensities against this atomic model: compute
     // R-free with an optimized bulk solvent and write 2Fo-Fc / Fo-Fc maps (--model). The caller parses
     // it (ParseRugnuxModel, writer/RugnuxModelFile.h).
@@ -1612,7 +1616,6 @@ class Rugnux {
     // --export-observations: the written stills merge's verdict on every observation, and its resolution cut.
     std::vector<std::vector<ObservationVerdict>> observation_verdicts_;
     std::optional<double> observation_d_min_;
-    static constexpr double STILLS_WINDOW_SIGMAS = 2.0;   // the window's half-width, in rocking widths
     static constexpr int STILLS_WINDOW_MIN_FRAMES = 2000;  // the sample: a tenth of the run, at least this
     static constexpr int STILLS_WINDOW_FRACTION = 10;
     // Stills: where the frames' pixel values pile up, against the file's saturation limit (see there).

rugnux/RugnuxImagePass.cpp

@@ -260,7 +260,7 @@ void Rugnux::ImagePass(PipelineLocals &p) {
     // predicted five to eight widths at low resolution, mostly empty, and cut the curve at one or two at
     // high resolution, so the partials there were never integrated. So the run's width is measured first,
     // on a sample of the frames integrated the old way (MeasureRunWidth, as the merge measures it), and
-    // every frame is then predicted through STILLS_WINDOW_SIGMAS of it.
+    // every frame is then predicted through config_.stills_window_sigmas of it.
     std::vector<int> window_frames;
     const bool stills_window = full && per_image_analysis && !calibration && !geometry_prepass && indexer
                                && !experiment_.IsRotationIndexing() && config_.spot_finding.indexing
@@ -452,13 +452,13 @@ void Rugnux::ImagePass(PipelineLocals &p) {
         for (const int o: window_frames)
             outcomes[o] = IntegrationOutcome{};
         if (stills_run_width_) {
-            const auto k = static_cast<float>(STILLS_WINDOW_SIGMAS);
+            const auto k = static_cast<float>(config_.stills_window_sigmas);
             indexer->SetStillsWindow(StillsWindow{.c0 = k * static_cast<float>(stills_run_width_->gamma0),
                                                   .ang = k * static_cast<float>(stills_run_width_->gamma_e),
                                                   .bw = k * static_cast<float>(stills_run_width_->bandwidth_sigma),
                                                   .q_scale = static_cast<float>(stills_run_width_->radial_scale)});
             Note(fmt::format("prediction window {:.1f} x the rocking width measured on {} frames, centred at "
-                             "radial scale {:+.2e}", STILLS_WINDOW_SIGMAS, window_frames.size(), radial_scale - 1.0));
+                             "radial scale {:+.2e}", config_.stills_window_sigmas, window_frames.size(), radial_scale - 1.0));
         }
     }
     for (int i = 0; i < image_workers; ++i)

rugnux/rugnux_cli.cpp

@@ -235,6 +235,7 @@ enum {
     OPT_NO_EXPORT_UNMERGED,
     OPT_EXPORT_UNMERGED_PARTIALS,
     OPT_EXPORT_OBSERVATIONS,
+    OPT_STILLS_WINDOW_SIGMAS,
     OPT_DUMP_OBSERVATIONS,
     OPT_INTEGRATOR,
     OPT_SIMPLE_STILLS,
@@ -319,6 +320,7 @@ static option long_options[] = {
     {"no-export-unmerged", no_argument, nullptr, OPT_NO_EXPORT_UNMERGED},
     {"export-unmerged-partials", no_argument, nullptr, OPT_EXPORT_UNMERGED_PARTIALS},
     {"export-observations", no_argument, nullptr, OPT_EXPORT_OBSERVATIONS},
+    {"stills-window-sigmas", required_argument, nullptr, OPT_STILLS_WINDOW_SIGMAS},
     {"dump-observations", required_argument, nullptr, OPT_DUMP_OBSERVATIONS},
     {"space-group", required_argument, nullptr, 'S'},
     {"anomalous", no_argument, nullptr, 'A'},
@@ -914,6 +916,7 @@ struct RugnuxCli {
     bool export_unmerged = true;            // on by default; --no-export-unmerged turns it off
     bool export_unmerged_partials = false;  // --export-unmerged-partials: the same, one row per image
     bool export_observations = false;       // --export-observations: <prefix>_obs.mtz, stills diagnostic
+    std::optional<double> stills_window_sigmas_arg;   // --stills-window-sigmas
     std::string dump_observations;   // diagnostic: dump unmerged -P rot3d fulls to this path
     std::optional<double> min_partiality_arg;   // --min-partiality; default per mode (RugnuxDefaultScalingSettings)
     std::optional<double> min_captured_fraction_arg;   // explicit --min-captured-fraction; default depends on rotation
@@ -1267,6 +1270,9 @@ int RugnuxCli::Parse(int argc, char **argv) {
         case OPT_EXPORT_OBSERVATIONS:
             export_observations = true;
             break;
+        case OPT_STILLS_WINDOW_SIGMAS:
+            stills_window_sigmas_arg = parse_double_arg(optarg, "--stills-window-sigmas", logger);
+            break;
         case OPT_DUMP_OBSERVATIONS:
             dump_observations = optarg;
             break;
@@ -3612,6 +3618,8 @@ int RugnuxInputRun::PrepareRugnuxInput() {
         };
     config.export_unmerged = export_unmerged;
     config.export_observations = export_observations;
+    if (stills_window_sigmas_arg)
+        config.stills_window_sigmas = *stills_window_sigmas_arg;
     config.export_unmerged_partials = export_unmerged_partials;
     config.model = model;
     config.force_mr = !mr_model.empty();