feat(diag): #266 - [stat-chain] apparatus across the vitae-to-movement chain

Three permanent low-volume probes: installed vitae record (id/type/key/
value) at ReplaceManifest, any vitae record dropped by GetMod's
spell-table prepass (retail's _vitae singleton never runs family
stacking - if this fires, hoist the Bucket-4 branch), and the full
recompute state (base skills, runMod, effective skills, active count).
One instrumented relog decides the break point.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.Core/Spells/EnchantmentMath.cs

@@ -100,7 +100,23 @@ public static class EnchantmentMath
         foreach (var ench in enchantments)
         {
             if (!table.TryGet(ench.SpellId, out var meta))
+            {
+                // #266 apparatus (permanent, rare): a VITAE record silently
+                // dropped by the spell-table lookup would zero the whole
+                // stat-chain effect — surface it. (Retail keeps _vitae on a
+                // dedicated singleton slot that never runs family stacking;
+                // if this line ever fires the faithful fix is hoisting the
+                // Bucket-4 branch above the table lookup.)
+                if (ench.Bucket == 4)
+                {
+                    System.Console.WriteLine(
+                        System.FormattableString.Invariant(
+                            $"[stat-chain] VITAE DROPPED by spell-table lookup: "
+                            + $"spell={ench.SpellId} value="
+                            + $"{(ench.StatModValue is float dv ? dv.ToString("F4") : "NULL")}"));
+                }
                 continue;
+            }
             // Family 0 means "no stacking bucket" — these don't dedup;
             // pass them through with a synthetic key per layer.
             uint bucket = meta.Family == 0 ? ench.LayerId | 0x80000000u : meta.Family;

src/AcDream.Core/Spells/Spellbook.cs

@@ -382,7 +382,21 @@ public sealed class Spellbook
         _vitalModCache.Clear();
         _skillModCache.Clear();
         foreach (ActiveEnchantmentRecord enchantment in enchantments)
+        {
             UpsertManifestEnchantment(enchantment);
+            // #266 apparatus (permanent, login-only volume): surface every
+            // installed VITAE record so the stat-chain break point is
+            // decidable from one log. Bucket 4 = vitae singleton class.
+            if (enchantment.Bucket == 4)
+            {
+                System.Console.WriteLine(
+                    System.FormattableString.Invariant(
+                        $"[stat-chain] login vitae installed: spell={enchantment.SpellId} "
+                        + $"statModType=0x{enchantment.StatModType ?? 0:X} "
+                        + $"key={enchantment.StatModKey ?? 0} "
+                        + $"value={(enchantment.StatModValue is float v ? v.ToString("F4") : "NULL")}"));
+            }
+        }
 
         for (int i = 0; i < _favoriteSpells.Length; i++)
         {

src/AcDream.Runtime/Gameplay/RuntimeCharacterState.cs

@@ -183,6 +183,18 @@ public sealed class RuntimeCharacterState : IDisposable
         int jump = _jumpSkillBase >= 0
             ? ApplySkillEnchantments(_jumpSkillBase, JumpSkillId)
             : -1;
+        // #266 apparatus (permanent, low-volume — fires only on skill-base or
+        // enchantment changes, the [snap] class): the full stat-chain state at
+        // each recompute. If vitae is active but runMod prints 1.0, the break
+        // is in GetSkillMod's record handling; if runMod is right but the
+        // felt speed doesn't change, the break is downstream of MovementSkills.
+        EnchantmentMath.VitalMod runMod = Spellbook.GetSkillMod(RunSkillId);
+        System.Console.WriteLine(
+            System.FormattableString.Invariant(
+                $"[stat-chain] base run={_runSkillBase} jump={_jumpSkillBase} "
+                + $"runMod={runMod.Multiplier:F4}x+{runMod.Additive:F1} "
+                + $"-> eff run={run} jump={jump} "
+                + $"(activeEnchantments={System.Linq.Enumerable.Count(Spellbook.ActiveEnchantments)})"));
         MovementSkills.Update(run, jump);
     }