possible popularity fix for playlists

shanty-playlist/src/scoring.rs

@@ -197,6 +197,9 @@ pub fn score_tracks(
             }
         }
 
+        // Apply to ALL tracks: popular ones get boosted, unknown ones get reduced.
+        // Factor range: unknown tracks get `1 - gp_strength` (minimum 0.01),
+        // top global track gets 1.0 + gp_strength (up to 2.0 at max setting).
         for t in &mut result {
             let playcount = t
                 .title
@@ -204,12 +207,15 @@ pub fn score_tracks(
                 .and_then(|title| global_playcounts.get(&title.to_lowercase()).copied())
                 .unwrap_or(0);
 
-            if playcount > 0 {
-                let global_pop = (playcount as f64 / global_max as f64).powf(gp_exponent);
-                // lerp(1.0, global_pop, gp_strength)
-                let factor = 1.0 + gp_strength * (global_pop - 1.0);
-                t.score *= factor;
-            }
+            let global_pop = if playcount > 0 {
+                (playcount as f64 / global_max as f64).powf(gp_exponent)
+            } else {
+                0.0
+            };
+            // Map global_pop [0, 1] to a factor centered around 1.0:
+            // global_pop=0 → 1.0 - gp_strength, global_pop=1 → 1.0 + gp_strength
+            let factor = (1.0 + gp_strength * (2.0 * global_pop - 1.0)).max(0.01);
+            t.score *= factor;
         }
     }