fix: pre-process D30 attack bonus at source for cross-client agreement

D30 bonus dice now rolled at defense request time, not in defense handler.
Sends boosted attackRoll + d30AttackEffects in socket/nextDefenseData
so both clients agree on the value. Adds stale flag for mulligan rerolls
to bypass stale pre-computed effects and process the new D30 fresh.

AGENTS.md

@@ -50,6 +50,12 @@ Fix Grit/Luck defense reaction dialog UX (stacking dialogs, multiple clicks, rev
 - **Import `hasD30Reroll` added** to `utils/combat.mjs`
 - **`bleed` top-level type handler added** to `processD30BonusDice` in `d30.mjs:79-81` — returns `specialEffect: "bleed"` same as combo path, so ranged attack bleed (values 5,10,15) creates reaction message and sets damage button bleed flag.
 
+### Pass 7 — Cross-Client Attack D30 Pre-Processing
+- **BUG FIX: D30 attack bonus processed at source (defense request time) instead of in defense handler** — `chat-reaction.mjs:136-148` now calls `processD30BonusDice` in the defense request button click handler, sends the boosted `attackRoll` and full `d30AttackEffects` result in the defense request. The `createChatMessage` handler at `chat-reaction.mjs:622-626` uses the pre-computed values instead of re-processing (avoids double dice roll and ensures both clients agree on attack value).
+- **Fix ensures cross-client agreement**: Player and GM clients see the same boosted attack roll because it's computed once at attack time and sent via socket, not separately per client in the defense handler.
+- **BUG FIX: `d30AttackEffects` not propagated through `_storeNextDefenseData`** — added `d30AttackEffects` to `nextDefenseData` in `combat.mjs:353-355` so the `createChatMessage` handler finds pre-computed values for same-client path (was silently falling back to legacy dice-roll, causing double boost).
+- **BUG FIX: `d30AttackPrecomputedStale` flag for mulligan rerolls** — added `chat-reaction.mjs:464` flag and check at `chat-reaction.mjs:632-634`. After a mulligan reroll updates `attackD30message`, the stale pre-computed effects are bypassed and the new D30 message is processed fresh via `processD30BonusDice`.
+
 ## Key Decisions
 - **Auto-roll bonus dice without dialog** — matches existing D30=27 (d6E) flow
 - **`buildDefenseReactionButtons` extracts only button-building** — defense while-loop structures differ between same-client and cross-client; merging loops risks behavioral divergence

module/hooks/chat-reaction.mjs

@@ -66,7 +66,7 @@ Hooks.on("renderChatMessageHTML", (message, html, data) => {
     btn.addEventListener("mouseleave", () => canvas.tokens.releaseAll())
 
     // Gestionnaire pour les boutons de demande de défense
-    btn.addEventListener("click", event => {
+    btn.addEventListener("click", async event => {
       event.preventDefault()
       event.stopPropagation()
 
@@ -140,13 +140,24 @@ Hooks.on("renderChatMessageHTML", (message, html, data) => {
         || (attackerWeapon?.system?.weaponType === "ranged")
         || (rollTargetOptions?.isRangedAttack === true)
 
+      // Process D30 attack bonus at source so both clients get the same boosted value.
+      // The d30BonusRoll chat message is created here (by _rollD30BonusDie inside processD30BonusDice).
+      let d30AttackEffects = null
+      let boostedAttackRoll = attackRoll
+      if (attackD30message && attacker) {
+        d30AttackEffects = await LethalFantasyUtils.processD30BonusDice(attackD30message, "attack", attackNaturalRoll, attacker, true)
+        if (d30AttackEffects.modifier) {
+          boostedAttackRoll = attackRoll + d30AttackEffects.modifier
+        }
+      }
+
       const defenseMsg = {
         type: "requestDefense",
         attackerName,
         attackerId,
         defenderName,
         weaponName,
-        attackRoll,
+        attackRoll: boostedAttackRoll,
         attackWeaponId,
         attackRollType,
         attackRollKey,
@@ -157,7 +168,8 @@ Hooks.on("renderChatMessageHTML", (message, html, data) => {
         damageTier,
         combatantId,
         tokenId,
-        isRanged: isRangedAttack
+        isRanged: isRangedAttack,
+        d30AttackEffects
       }
 
       // Envoyer le message socket à l'utilisateur contrôlant le combatant
@@ -448,6 +460,10 @@ Hooks.on("createChatMessage", async (message) => {
   let d30Bleed = false
   let d30DamageMultiplier = 1
   let d30DrMultiplier = 1
+  // Tracks whether the pre-computed D30 effects are stale (invalidated by a mulligan reroll
+  // that produced a new D30 message). When a reroll updates attackD30message, the original
+  // d30AttackEffects from the defense request no longer apply — the new D30 must be processed.
+  let d30AttackPrecomputedStale = false
 
   do {
     mulliganRestart = false
@@ -605,26 +621,42 @@ Hooks.on("createChatMessage", async (message) => {
     // ── D30 bonus dice (attack) — resolved before grit/luck ────────────────
     if (attackD30message && !attackD30Processed) {
       const preD30AttackRoll = attackRollFinal
-      const canDialog = isPrimaryController(attacker)
-      const d30Result = await LethalFantasyUtils.processD30BonusDice(attackD30message, "attack", attackNaturalRoll, attacker, canDialog)
+      const canShow = isPrimaryController(attacker)
+
+      // Use pre-computed D30 effects (processed at attack time in the defense
+      // request handler) to avoid re-rolling dice on the defense handler.
+      // This ensures both clients agree on the boosted attack roll.
+      // When d30AttackPrecomputedStale is true (invalidated by a mulligan reroll),
+      // skip the pre-computed effects and process the new D30 message fresh.
+      const usePrecomputed = !!attackData.d30AttackEffects && !d30AttackPrecomputedStale
+      const d30Result = usePrecomputed
+        ? attackData.d30AttackEffects
+        : await LethalFantasyUtils.processD30BonusDice(attackD30message, "attack", attackNaturalRoll, attacker, canShow)
+      d30AttackPrecomputedStale = false
+
       if (d30Result.modifier) {
-        attackRollFinal += d30Result.modifier
-        if (d30Result.modifier > 0 && canDialog) {
+        if (!usePrecomputed) {
+          // Legacy or post-reroll path: bonus was just rolled, apply now
+          attackRollFinal += d30Result.modifier
+        }
+        // d30BonusRoll message was created at attack time (pre-processed)
+        // or inside _rollD30BonusDie (legacy). Either way, show the application.
+        if (d30Result.modifier > 0 && canShow) {
           await createReactionMessage(attacker, {type:"d30Bonus", actorName:attackerName, value:d30Result.modifier, side:"attack"})
         }
       }
-      if (d30Result.specialEffect === "flag" && canDialog) {
+      if (d30Result.specialEffect === "flag" && canShow) {
         await createReactionMessage(attacker, {type:"d30Flag", actorName:attackerName, specialName:d30Result.specialName||"Special Effect"})
       }
       if (d30Result.specialEffect === "bleed") {
         d30Bleed = true
-        if (canDialog) {
+        if (canShow) {
           await createReactionMessage(attacker, {type:"d30Bleed", actorName:attackerName})
         }
       }
       if (d30Result.specialEffect === "damageMultiplier") {
         d30DamageMultiplier = d30Result.multiplier
-        if (canDialog) {
+        if (canShow) {
           await createReactionMessage(attacker, {type:"d30DamageMultiplier", actorName:attackerName, value:d30Result.multiplier})
         }
       }
@@ -735,6 +767,8 @@ Hooks.on("createChatMessage", async (message) => {
           if (reroll.options?.D30message) {
             attackD30message = reroll.options.D30message
             attackD30Processed = false
+            // Invalidate pre-computed effects — the new D30 message must be processed fresh
+            d30AttackPrecomputedStale = true
           }
           // Restart the full comparison so both sides can react to the new roll
           mulliganRestart = true

module/utils/combat.mjs

@@ -302,6 +302,7 @@ export async function showDefenseRequest(msg) {
   const attackD30result = msg.attackD30result
   const attackD30message = msg.attackD30message
   const attackRerollContext = msg.attackRerollContext
+  const d30AttackEffects = msg.d30AttackEffects
   const combatantId = msg.combatantId
   const tokenId = msg.tokenId
 
@@ -351,6 +352,7 @@ export async function showDefenseRequest(msg) {
       damageTier: msg.damageTier,
       defenderId: defender.id, defenderTokenId,
       ...(msg.attackNaturalRoll !== undefined && { attackNaturalRoll: msg.attackNaturalRoll }),
+      ...(d30AttackEffects !== undefined && { d30AttackEffects }),
       ...(opts.isRanged !== undefined && { isRanged: opts.isRanged })
     }
   }