diff --git a/apps/api/src/routes/boss.ts b/apps/api/src/routes/boss.ts
index 03379cf..fe41a29 100644
--- a/apps/api/src/routes/boss.ts
+++ b/apps/api/src/routes/boss.ts
@@ -8,6 +8,7 @@
 /* eslint-disable max-statements -- Boss handler requires many statements */
 /* eslint-disable complexity -- Boss handler has inherent complexity */
 /* eslint-disable stylistic/max-len -- Long lines in combat logic */
+/* eslint-disable max-lines -- Boss route with full combat logic and helpers exceeds line limit */
 import {
   computeSetBonuses,
   getActiveCompanionBonus,
@@ -298,14 +299,20 @@ bossRouter.post("/challenge", async(context) => {
         state.resources.crystals = state.resources.crystals + crystalsAwarded;
       }
 
-      // First-kill bounty — look up authoritative bounty from static data
+      // First-kill bounty — only awarded once across all prestiges
       const staticBoss = defaultBosses.find((b) => {
         return b.id === body.bossId;
       });
 
       // eslint-disable-next-line capitalized-comments -- v8 ignore
-      /* v8 ignore next -- @preserve */
-      const bountyRunestones = staticBoss?.bountyRunestones ?? 0;
+      /* v8 ignore next 7 -- @preserve */
+      const bountyRunestones
+        = boss.bountyRunestonesClaimed === true
+          ? 0
+          : staticBoss?.bountyRunestones ?? 0;
+      if (bountyRunestones > 0) {
+        boss.bountyRunestonesClaimed = true;
+      }
       state.prestige.runestones = state.prestige.runestones + bountyRunestones;
 
       rewards = {
diff --git a/apps/api/src/services/prestige.ts b/apps/api/src/services/prestige.ts
index d05de0b..8f40a35 100644
--- a/apps/api/src/services/prestige.ts
+++ b/apps/api/src/services/prestige.ts
@@ -206,6 +206,20 @@ const buildPostPrestigeState = (
 
   const freshState = initialGameState(currentState.player, characterName);
 
+  /*
+   * Preserve first-kill (bounty claimed) status across the prestige reset so
+   * the one-time bounty is never re-awarded in subsequent runs.
+   */
+  const bossesWithBountyClaimed = freshState.bosses.map((freshBoss) => {
+    const currentBoss = currentState.bosses.find((candidate) => {
+      return candidate.id === freshBoss.id;
+    });
+    if (currentBoss?.bountyRunestonesClaimed === true) {
+      return { ...freshBoss, bountyRunestonesClaimed: true };
+    }
+    return freshBoss;
+  });
+
   // Compute current-run contributions to accumulate into lifetime totals
   const runBossesDefeated = currentState.bosses.filter((boss) => {
     return boss.status === "defeated";
@@ -227,6 +241,8 @@ const buildPostPrestigeState = (
     ...freshState,
     // Achievements are permanent — earned achievements survive all prestiges
     achievements: currentState.achievements,
+    // Boss statuses reset for gameplay, but first-kill claimed flag is preserved
+    bosses:       bossesWithBountyClaimed,
     lastTickAt:   Date.now(),
 
     /*
diff --git a/apps/api/test/routes/boss.spec.ts b/apps/api/test/routes/boss.spec.ts
index 37b2aca..98fa037 100644
--- a/apps/api/test/routes/boss.spec.ts
+++ b/apps/api/test/routes/boss.spec.ts
@@ -305,4 +305,25 @@ describe("boss route", () => {
     const res = await challenge({ bossId: "test_boss" });
     expect(res.status).toBe(500);
   });
+
+  it("does not re-award bounty runestones when bountyRunestonesClaimed is true", async () => {
+    const state = makeState({
+      bosses: [makeBoss({
+        bountyRunestonesClaimed: true,
+        currentHp:               100,
+        damagePerSecond:         1,
+        maxHp:                   100,
+      })] as GameState["bosses"],
+      adventurers: [makeAdventurer()] as GameState["adventurers"],
+      prestige:    { count: 0, productionMultiplier: 1, purchasedUpgradeIds: [], runestones: 5 },
+      zones:       [],
+    });
+    vi.mocked(prisma.gameState.findUnique).mockResolvedValueOnce({ state } as never);
+    vi.mocked(prisma.gameState.update).mockResolvedValueOnce({} as never);
+    const res = await challenge({ bossId: "test_boss" });
+    expect(res.status).toBe(200);
+    const body = await res.json() as { won: boolean; rewards: { bountyRunestones: number } };
+    expect(body.won).toBe(true);
+    expect(body.rewards.bountyRunestones).toBe(0);
+  });
 });
diff --git a/apps/api/test/services/prestige.spec.ts b/apps/api/test/services/prestige.spec.ts
index c913e74..cbff3d0 100644
--- a/apps/api/test/services/prestige.spec.ts
+++ b/apps/api/test/services/prestige.spec.ts
@@ -292,6 +292,33 @@ describe("buildPostPrestigeState", () => {
     expect(prestigeState.player.lifetimeBossesDefeated).toBe(1);
   });
 
+  it("preserves bountyRunestonesClaimed flag on bosses across prestige", () => {
+    const claimedBoss = {
+      bountyRunestones:        5,
+      bountyRunestonesClaimed: true,
+      crystalReward:           0,
+      currentHp:               0,
+      damagePerSecond:         10,
+      description:             "A boss",
+      equipmentRewards:        [] as string[],
+      essenceReward:           0,
+      goldReward:              100,
+      id:                      "troll_king",
+      maxHp:                   100,
+      name:                    "Troll King",
+      prestigeRequirement:     0,
+      status:                  "defeated" as const,
+      upgradeRewards:          [] as string[],
+      zoneId:                  "verdant_vale",
+    };
+    const state = makeMinimalState({ bosses: [ claimedBoss ] as GameState["bosses"] });
+    const { prestigeState } = buildPostPrestigeState(state, "Tester");
+    const matchingBoss = prestigeState.bosses.find((boss) => {
+      return boss.id === "troll_king";
+    });
+    expect(matchingBoss?.bountyRunestonesClaimed).toBe(true);
+  });
+
   it("accumulates completed quests into lifetime total", () => {
     const quest = {
       id:          "q_1",
diff --git a/apps/web/src/components/game/bossPanel.tsx b/apps/web/src/components/game/bossPanel.tsx
index c324a61..df47f6e 100644
--- a/apps/web/src/components/game/bossPanel.tsx
+++ b/apps/web/src/components/game/bossPanel.tsx
@@ -126,7 +126,9 @@ const BossCard = ({
             {" Equipment"}
           </span>
         }
-        {boss.status !== "defeated" && boss.bountyRunestones > 0
+        {boss.status !== "defeated"
+        && boss.bountyRunestones > 0
+        && boss.bountyRunestonesClaimed !== true
           && <span className="boss-bounty">
             {"🔮 "}
             {boss.bountyRunestones}
diff --git a/packages/types/src/interfaces/boss.ts b/packages/types/src/interfaces/boss.ts
index eabf646..9a2a91e 100644
--- a/packages/types/src/interfaces/boss.ts
+++ b/packages/types/src/interfaces/boss.ts
@@ -59,6 +59,13 @@ interface Boss {
    * One-time runestone bounty awarded on first-ever defeat.
    */
   bountyRunestones: number;
+
+  /**
+   * Whether the first-kill runestone bounty has already been claimed.
+   * Set to true on first defeat and preserved across all prestiges so the
+   * bounty is never re-awarded in subsequent runs.
+   */
+  bountyRunestonesClaimed?: boolean;
 }
 
 export type { Boss, BossStatus };