Let charged guardian heals act without enemies and fix mixed S2 triggers (#406)

docs/history/0.2.3.md

@@ -143,3 +143,22 @@ share the examples' display behavior; the drag template alone cannot establish t
 Tests cover real push/pull skill paths, default/override metadata, snapshot reversal, and an earlier attack
 arriving after slide prestart in either field direction. Golden metadata deliberately omits the display flag.
 
+### 28.10 Charged guardian heals and mixed-skill activation — #406
+
+Reported by @ChengCC0101. 塞雷娅 / 黍 S1 previously required an enemy to supply the attack that their charged heal
+replaces. [PRTS 塞雷娅](https://prts.wiki/w/塞雷娅) and [黍](https://prts.wiki/w/黍) describe an eligible ally at
+half HP or below, with the normal attack cadence. `updateAlly` now checks this alternate target after its cooldown
+and control/disarm checks; an enemy is unnecessary. An invalid pending heal still returns its charge. This corrects
+the enemy requirement inferred in historical §27.31; that earlier conclusion is superseded.
+
+[PRTS 凯尔希·思衡托](https://prts.wiki/w/凯尔希·思衡托) S2 can attack enemies and heal allies. Its automatic
+activation now accepts either target kind on its expanded range, under the existing player-approved range strategy
+and operation cooldown. S1/S3 keep their existing trigger rules. This addresses the healing/activation parts of #406;
+the separate fatal-hit/silence report still needs an independently justified damage-order fix.
+
+Verification: 104 targeted tests pass. Independent interaction review found and verified fixes for a one-frame
+cadence delay and premature charge use while disarmed; normal/100-ASPD intervals are exactly 1.2/0.6 s.
+Sleep, silence, no-heal targets, charge refunds, cooperative healing and S2 target selectability remain covered.
+
+Golden: all 285 scenarios recomputed; `diy-059`, `diy-133` change because
+charged heals now act without enemy targets and S2 can open for enemies. Other scenarios remain byte-identical.