fix(rules): shield of faith grants its SRD deflection AC buff (+2, +1 per six caster levels, max +5) via a new BuffEffect flat scaling

data/spells/shield_of_faith.json

@@ -6,6 +6,15 @@
   "save": "will",
   "base_dc": 10,
   "cast_time": "standard",
-  "effects": [],
+  "effects": [
-  "description": "A shimmering magical field grants the target a +2 deflection bonus to AC (+1 per six caster levels, max +5) for 1 min./level. Will negates (harmless). Simplified: the engine has no self-buff encoding that preserves the pinned default-policy casting order, so no mechanical effect is applied."
+    {
+      "type": "buff",
+      "modifiers": [
+        { "target": "ac", "value": 2, "bonus_type": "deflection" }
+      ],
+      "duration_rounds": 10,
+      "scaling_flat": { "amount": 1, "per_levels": 6, "max": 3 }
+    }
+  ],
+  "description": "SRD spells/shield-of-faith.md: abjuration, level 1 (cleric/inquisitor/oracle/warpriest), range touch, duration 1 min./level, Will negates (harmless), spell resistance yes (harmless). The subject gains a +2 deflection bonus to AC, +1 per six caster levels (maximum +5 at 18th). Duration 1 min/level approximated as 10 rounds (the engine has no per-level buff duration; cf. mirror image)."
 }

src/pf1e_simulator/combat.py

@@ -6461,7 +6461,10 @@ class CombatEngine:
                 effect, target, caster=caster, saved=saved,
                 empower=empower, maximize=maximize, spell_name=spell_name,
             )
-        return self._apply_buff_effect(effect, target, spell_name=spell_name)
+        return self._apply_buff_effect(
+            effect, target, spell_name=spell_name,
+            caster_level=caster.combatant.level,
+        )
 
     def _apply_damage_effect(
         self,
@@ -6678,16 +6681,42 @@ class CombatEngine:
         return f"+{actual} HP"
 
     def _apply_buff_effect(
-        self, effect: BuffEffect, target: CombatantState, *, spell_name: str
+        self,
+        effect: BuffEffect,
+        target: CombatantState,
+        *,
+        spell_name: str,
+        caster_level: int,
     ) -> str:
+        # PF1e caster-level scaling on buff values (SRD shield of faith
+        # "+2 deflection, +1 per six caster levels (maximum +5)"): the flat
+        # extra is added to EVERY modifier of the buff.
+        modifiers = effect.modifiers
+        if effect.scaling_flat is not None:
+            extra = min(
+                effect.scaling_flat.max_amount,
+                (caster_level // effect.scaling_flat.per_levels)
+                * effect.scaling_flat.amount,
+            )
+            if extra > 0:
+                modifiers = tuple(
+                    StatModifier(
+                        target=mod.target,
+                        value=mod.value + extra,
+                        bonus_type=mod.bonus_type,
+                        condition=mod.condition,
+                        weapon_filter=mod.weapon_filter,
+                    )
+                    for mod in modifiers
+                )
         target.active_buffs.append(
             ActiveBuff(
-                modifiers=effect.modifiers,
+                modifiers=modifiers,
                 rounds_left=effect.duration_rounds,
                 source=f"spell: {spell_name}",
             )
         )
-        return f"buff {len(effect.modifiers)} mods ({effect.duration_rounds}r)"
+        return f"buff {len(modifiers)} mods ({effect.duration_rounds}r)"
 
     def _apply_penalty_effect(
         self,
@@ -6912,7 +6941,11 @@ class CombatEngine:
             )
         if isinstance(effect, BuffEffect):
             duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
-            return BuffEffect(modifiers=effect.modifiers, duration_rounds=duration)
+            return BuffEffect(
+                modifiers=effect.modifiers,
+                duration_rounds=duration,
+                scaling_flat=effect.scaling_flat,
+            )
         if isinstance(effect, PenaltyEffect):
             duration = (
                 effect.duration_rounds_per_level * 2

src/pf1e_simulator/spells.py

@@ -213,8 +213,17 @@ class HealEffect:
 
 @dataclass(frozen=True)
 class BuffEffect:
+    """Transient stat modifiers (PF1e buff spells).
+
+    ``scaling_flat`` (SRD shield of faith "+2 deflection, +1 per six caster
+    levels (maximum +5)", divine favor "+1 per three caster levels (maximum
+    +3)") adds the resolved flat bonus to EVERY modifier's value at cast
+    time, mirroring ``DamageEffect.effective_formula``'s flat scaling.
+    """
+
     modifiers: tuple[StatModifier, ...]
     duration_rounds: int
+    scaling_flat: DamageFlatScaling | None = None
 
 
 @dataclass(frozen=True)
@@ -611,9 +620,12 @@ def _parse_heal_effect(effect: dict[str, Json]) -> HealEffect:
 
 
 def _parse_buff_effect(effect: dict[str, Json]) -> BuffEffect:
+    flat_raw = effect.get("scaling_flat")
+    scaling_flat = None if flat_raw is None else _parse_flat_scaling(flat_raw)
     return BuffEffect(
         modifiers=tuple(_parse_modifier(m) for m in _as_list(effect["modifiers"])),
         duration_rounds=_as_int(effect.get("duration_rounds", 0)),
+        scaling_flat=scaling_flat,
     )
 
 

tests/test_pc_combat_golden.py

@@ -61,33 +61,66 @@ class TestGoldenCombats:
 
         Golden updated by the Weapon Focus conformance fix: the feat filter
         "Pistol" now matches her pistol names ("... (pistolet ?)"), so every
-        pistol attack gains the +1 feat bonus. Line-by-line:
+        pistol attack gains the +1 feat bonus.
-        - rounds 1-3: unchanged (Bull's Strength casts, goblin misses).
+
-        - round 4 tammara: total 15 -> 16 (the +1 Weapon Focus), AC 16 is now
+        Updated again by the SRD shield-of-faith fix (data/spells/
-          met: MISS -> HIT 17 damage, goblin 6 -> -11 (below its -CON death
+        shield_of_faith.json now carries its real +2 deflection AC buff):
-          threshold).
+        _find_buff_spell returns the FIRST buff spell in her known-spell
-        - "goblin down" + "players win in 4 rounds": the goblin dies on round
+        order, and Shield of Faith (list index 30) precedes Bull's Strength
-          4, so the old rounds 4-10 goblin shots and the draw are gone.
+        (index 46) — so the policy's buff pick is now Shield of Faith.
+        Line-by-line:
+        - rounds 1-4 tammara: "cast Shield of Faith ... DC14 SAVED -> buff 1
+          mods (10r)" — DC 14 = 10 + spell level 1 + her +3 Wis; the deflection
+          buff does not stack with itself, so the re-casts just refresh it. She
+          has four level-1 slots, so the buff phase now runs rounds 1-4 (the
+          old Bull's Strength phase ran rounds 1-3 on three level-2 slots).
+        - rounds 1-10 goblin: "AC 22" (was 20) — the +2 deflection raises her
+          AC; the goblin's d20=15+4-2=17 shot still misses.
+        - rounds 5-10 tammara: "d20=10+9-6=14 AC 16 -> MISS" — out of level-1
+          slots she shoots; without Bull's Strength's +2 enhancement attack
+          bonus the scripted d20=10 shot totals 14, below the goblin's AC 16.
+        - "battle over: draw after 10 rounds": the goblin is never dropped
+          within the round cap. This is a default_policy first-match heuristic
+          artifact (Shield of Faith is a legitimate SRD buff, just a
+          defensively-picked one), not an SRD regression.
         """
         result, _ = run_golden("tammara")
-        assert result.winner == "players"
+        assert result.winner is None
-        assert result.rounds == 4
+        assert result.rounds == 10
         assert result.transcript == (
             "initiative: tammara d20=15+7=22",
             "initiative: goblin d20=10+6=16",
-            ("round 1 tammara: cast Bull's Strength vs tammara DC15 SAVED -> buff 3 mods (60r) "
+            ("round 1 tammara: cast Shield of Faith vs tammara DC14 SAVED "
-             "(36->36)"),
+             "-> buff 1 mods (10r) (36->36)"),
-            "round 1 goblin: short bow vs tammara d20=15+4-2=17 AC 20 -> MISS",
+            "round 1 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
-            ("round 2 tammara: cast Bull's Strength vs tammara DC15 SAVED -> buff 3 mods (60r) "
+            ("round 2 tammara: cast Shield of Faith vs tammara DC14 SAVED "
-             "(36->36)"),
+             "-> buff 1 mods (10r) (36->36)"),
-            "round 2 goblin: short bow vs tammara d20=15+4-2=17 AC 20 -> MISS",
+            "round 2 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
-            ("round 3 tammara: cast Bull's Strength vs tammara DC15 SAVED -> buff 3 mods (60r) "
+            ("round 3 tammara: cast Shield of Faith vs tammara DC14 SAVED "
-             "(36->36)"),
+             "-> buff 1 mods (10r) (36->36)"),
-            "round 3 goblin: short bow vs tammara d20=15+4-2=17 AC 20 -> MISS",
+            "round 3 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
-            ("round 4 tammara: Braises d'Automne (pistolet ?) vs goblin d20=10+9-6=16 "
+            ("round 4 tammara: cast Shield of Faith vs tammara DC14 SAVED "
-             "AC 16 -> HIT 17 damage (6->-11)"),
+             "-> buff 1 mods (10r) (36->36)"),
-            "round 4 tammara: goblin down",
+            "round 4 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
-            "battle over: players win in 4 rounds",
+            ("round 5 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 5 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            ("round 6 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 6 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            ("round 7 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 7 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            ("round 8 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 8 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            ("round 9 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 9 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            ("round 10 tammara: Braises d'Automne (pistolet ?) vs goblin "
+             "d20=10+9-6=14 AC 16 -> MISS"),
+            "round 10 goblin: short bow vs tammara d20=15+4-2=17 AC 22 -> MISS",
+            "battle over: draw after 10 rounds",
         )
 
     def test_tammara_vs_lich(self):
@@ -98,6 +131,13 @@ class TestGoldenCombats:
         missiles (16 + 11 + 16 = 43) drop Tammara below 0 hp on round 1; the
         remaining two are lost (the engine's target-drops-mid-sequence
         convention), so the lich wins in 1 round.
+
+        Updated by the SRD shield-of-faith fix: her round-1 buff pick is now
+        Shield of Faith (first buff spell in her known-spell order, index 30
+        before Bull's Strength's 46) — "cast Shield of Faith ... DC14 SAVED ->
+        buff 1 mods (10r)" (DC 14 = 10 + level 1 + her +3 Wis). Magic Missile
+        auto-hits and ignores the +2 deflection it would otherwise grant, so
+        the lich's line and the outcome are unchanged.
         """
         result, _ = run_golden("tammara", "lich")
         assert result.winner == "monsters"
@@ -105,8 +145,8 @@ class TestGoldenCombats:
         assert result.transcript == (
             "initiative: tammara d20=15+7=22",
             "initiative: lich d20=10+6=16",
-            ("round 1 tammara: cast Bull's Strength vs tammara DC15 SAVED -> buff 3 mods (60r) "
+            ("round 1 tammara: cast Shield of Faith vs tammara DC14 SAVED "
-             "(36->36)"),
+             "-> buff 1 mods (10r) (36->36)"),
             "round 1 lich: cast Magic Missile vs tammara DC16 NO SAVE -> 43 damage (36->-7)",
             "battle over: monsters win in 1 rounds",
         )

tests/test_spells.py

@@ -636,6 +636,35 @@ class TestBullsStrength:
         assert any("buff" in line for line in engine._transcript)
 
 
+class TestShieldOfFaithScaling:
+    """Given: SRD shield-of-faith "+2 deflection bonus to AC, +1 per six
+    caster levels (maximum +5)"
+    When: casters of different levels cast it
+    Then: the AC modifier is 2 + min(3, level // 6) — +2 at 5th, +3 at 6th,
+    +5 at 18th."""
+
+    def _ac_value(self, level: int) -> int:
+        caster = _make_caster(level=level)
+        target = _make_target()
+        engine, c, t = _make_engine(caster, target, [3, 3], target_pos=(1, 0),
+                                         target_side="players")
+        engine._cast_spell(c, t, "Shield of Faith")
+        ac_mods = [m for b in t.active_buffs for m in b.modifiers if m.target == "ac"]
+        assert len(ac_mods) == 1
+        assert ac_mods[0].bonus_type == "deflection"
+        return ac_mods[0].value
+
+    def test_base_bonus_below_sixth_level(self) -> None:
+        assert self._ac_value(5) == 2
+
+    def test_first_step_at_sixth_level(self) -> None:
+        assert self._ac_value(6) == 3
+
+    def test_capped_at_five(self) -> None:
+        assert self._ac_value(18) == 5
+        assert self._ac_value(20) == 5
+
+
 class TestBlessAlliesOnly:
     """Given: a caster casting Bless (SRD: 50-ft burst, "the caster and all
     allies")