fix(rules): selective channeling modeled as a policy-chosen exclusion - Action(kind=channel_energy) gains channel_exclude, honored only with the Selective Channeling feat and capped at the Charisma modifier (SRD feats/selective-channeling.md: 'choose a number of targets in the area up to your Charisma modifier... not affected by your channeled energy'); without the feat the list is ignored and logged (SRD Normal: all targets affected); observable in current data because heal mode also heals living ENEMIES in the burst (deny them the heal) and harm mode can spare an undead ally; default_policy never excludes (opt-in, like weapon_id/destination/metamagic); golden transcripts unchanged; +5 tests

src/pf1e_simulator/combat.py

@@ -191,6 +191,9 @@ _FIRING_MELEE_PENALTY = -4  # PF1e: ranged attack into melee
 _FIRING_MELEE_SAFE_FT = 10  # PF1e: 2 cells (10 ft) = the -4 penalty is avoided
 _SNEAK_ATTACK_FEATURE = "Sneak Attack"  # PF1e: rogue class feature (precision dice)
 _PRECISE_SHOT_FEATURE = "Precise Shot"  # PF1e: feat negating firing-into-melee penalty
+# PF1e: feat letting a channeler exclude up to her Cha modifier targets from
+# her own channel energy (SRD feats/selective-channeling.md).
+_SELECTIVE_CHANNELING_FEAT = "Selective Channeling"
 _IMPROVED_CRITICAL_FEATURE = "Improved Critical"  # PF1e: feat doubling the threat range
 _CRIT_RANGE_BASE = 21  # threat range top is 21 - min natural die (20 -> 20-20)
 _DYING_DC = 10  # PF1e: DC of the per-round stabilization Constitution check
@@ -1114,6 +1117,12 @@ class Action:
     deed_name: str | None = None  # "up_close_and_deadly", "quick_clear"
     class_ability: str | None = None  # "deed"|"spell_combat"|"inspire_courage"|"hex"|"channel"
     channel_mode: Literal["heal", "harm"] | None = None  # channel energy polarity for this use
+    # PF1e (SRD Feats > Selective Channeling): "When you channel energy, you
+    # can choose a number of targets in the area up to your Charisma
+    # modifier. These targets are not affected by your channeled energy."
+    # Ids the channeler's policy excludes from THIS channel; honored only
+    # with the feat, capped at the Charisma modifier (excess entries drop).
+    channel_exclude: tuple[str, ...] = ()
     direction: tuple[int, int] | None = None  # steering for directional maneuvers
     trick_condition: TrickCondition | None = None  # dirty trick condition choice
     # weapon id for attack / full_attack / retrieve_weapon / repair_weapon
@@ -4698,7 +4707,8 @@ class CombatEngine:
         kind = action.kind
         if kind == "channel_energy":
             self._execute_channel_energy(
-                state, target, action.channel_mode or "heal"
+                state, target, action.channel_mode or "heal",
+                exclude=action.channel_exclude,
             )
         elif kind == "hex":
             self._execute_hex(state, target, action.hex_name)
@@ -5752,6 +5762,8 @@ class CombatEngine:
         state: CombatantState,
         target: CombatantState | None,
         channel_mode: Literal["heal", "harm"],
+        *,
+        exclude: tuple[str, ...] = (),
     ) -> None:
         """Execute channel energy (positive energy, burst 30ft, 2d6).
 
@@ -5760,7 +5772,8 @@ class CombatEngine:
         (PF1e Channel Energy: positive energy heals living creatures and
         damages undead creatures within 30 feet). Damaged creatures get a
         Will save (DC 10 + half the channeler's level + her Cha modifier)
-        for half damage (CRB Channel Energy).
+        for half damage (CRB Channel Energy). ``exclude`` is the Selective
+        Channeling payload (see ``_selective_channel``).
         """
         if not state.spend_resource("channel_energy", 1):
             self._log(
@@ -5784,6 +5797,7 @@ class CombatEngine:
 
         wanted_type = "living" if channel_mode == "heal" else "undead"
         hit = [s for s in affected if s.combatant.creature_type == wanted_type]
+        hit = self._selective_channel(state, hit, exclude)
 
         # 2d6 damage/healing
         dmg = 1 + self._rng.roll_die(11)  # 2d6
@@ -5808,6 +5822,45 @@ class CombatEngine:
             f"channel energy ({channel_mode}) {dmg} -> {len(hit)} targets"
         )
 
+    def _selective_channel(
+        self,
+        state: CombatantState,
+        hit: list[CombatantState],
+        exclude: tuple[str, ...],
+    ) -> list[CombatantState]:
+        """Apply the Selective Channeling feat to a resolved channel target list.
+
+        PF1e (SRD Feats > Selective Channeling, feats/selective-channeling.md):
+        "When you channel energy, you can choose a number of targets in the
+        area up to your Charisma modifier. These targets are not affected by
+        your channeled energy. Normal: All targets in a 30-foot burst are
+        affected when you channel energy. You can only choose whether or not
+        you are affected." Without the feat the exclusion list is ignored
+        (the engine's default is "all targets affected, channeler included");
+        with it, the first ``Cha modifier`` ids are dropped from the affected
+        set (deterministic truncation of an over-long list). The policy
+        chooses the ids: default_policy never excludes (available via a
+        custom policy, like the other opt-in payloads).
+        """
+        if not exclude:
+            return hit
+        if not self._has_feat(state, _SELECTIVE_CHANNELING_FEAT):
+            self._log(
+                f"round {self._current_round} {state.combatant.id}: "
+                f"selective channeling ignored (no feat)"
+            )
+            return hit
+        cha_mod = (state.combatant.abilities.cha_score - 10) // 2
+        allowed = set(exclude[:max(0, cha_mod)])
+        kept = [s for s in hit if s.combatant.id not in allowed]
+        dropped = [s.combatant.id for s in hit if s.combatant.id in allowed]
+        if dropped:
+            self._log(
+                f"round {self._current_round} {state.combatant.id}: "
+                f"selective channeling excludes {', '.join(dropped)}"
+            )
+        return kept
+
     def _channel_heal(
         self, state: CombatantState, affected_state: CombatantState, dmg: int
     ) -> None: