diff --git a/packages/generated-patterns/integration/patterns/minimal-conflict-repro.pattern.ts b/packages/generated-patterns/integration/patterns/minimal-conflict-repro.pattern.ts
new file mode 100644
index 0000000000..0111e21582
--- /dev/null
+++ b/packages/generated-patterns/integration/patterns/minimal-conflict-repro.pattern.ts
@@ -0,0 +1,30 @@
+/// <cts-enable />
+import { type Cell, cell, Default, handler, lift, recipe } from "commontools";
+
+interface Item {
+  id?: string;
+}
+
+const action = handler(
+  (_event, context: { items: Cell<Item[]>; sequence: Cell<number> }) => {
+    // Minimal repro: Removing either of these removes the conflict
+    context.items.set([]);
+    context.sequence.set(context.sequence.get() + 1);
+  },
+);
+
+export const conflictRepro = recipe<{ items: Default<Item[], []> }>(
+  ({ items }) => {
+    const sequence = cell(0);
+
+    // Minimal repro: Removing the lift and the map removes the conflict
+    lift((item: Item[]) => item.map((_) => ({})))(items);
+
+    return {
+      action: action({
+        items,
+        sequence,
+      }),
+    };
+  },
+);
diff --git a/packages/generated-patterns/integration/patterns/minimal-conflict-repro.test.ts b/packages/generated-patterns/integration/patterns/minimal-conflict-repro.test.ts
new file mode 100644
index 0000000000..60c3960d06
--- /dev/null
+++ b/packages/generated-patterns/integration/patterns/minimal-conflict-repro.test.ts
@@ -0,0 +1,45 @@
+import { describe, it } from "@std/testing/bdd";
+import { runPatternScenario } from "../pattern-harness.ts";
+import type { PatternIntegrationScenario } from "../pattern-harness.ts";
+
+interface Item {
+  id?: string;
+}
+
+interface MinimalConflictReproArgument {
+  items?: Item[];
+}
+
+export const minimalLeadScoringScenario: PatternIntegrationScenario<
+  MinimalConflictReproArgument
+> = {
+  name: "minimal conflict repro",
+  module: new URL("./minimal-conflict-repro.pattern.ts", import.meta.url),
+  exportName: "conflictRepro",
+  argument: {
+    items: [
+      {
+        id: "acme",
+      },
+    ],
+  },
+  steps: [
+    {
+      events: [{
+        stream: "action",
+        payload: {},
+      }],
+      expect: [],
+    },
+  ],
+};
+
+export const scenarios = [minimalLeadScoringScenario];
+
+describe("minimal conflict repro", () => {
+  for (const scenario of scenarios) {
+    it(scenario.name, async () => {
+      await runPatternScenario(scenario);
+    });
+  }
+});
diff --git a/packages/runner/src/storage/transaction/chronicle.ts b/packages/runner/src/storage/transaction/chronicle.ts
index 61b84a9943..0df68900dc 100644
--- a/packages/runner/src/storage/transaction/chronicle.ts
+++ b/packages/runner/src/storage/transaction/chronicle.ts
@@ -141,6 +141,7 @@ export class Chronicle {
 
     // Validate against current state (replica + any overlapping novelty)
     const rebase = this.rebase(loaded);
+
     if (rebase.error) {
       return rebase;
     }
@@ -298,10 +299,18 @@ export class Chronicle {
         // If the merged value is neither `undefined` nor the existing value,
         // create an assertion referring to the loaded fact in a causal
         // reference.
+        const factToRefer = loaded.cause ? normalizeFact(loaded) : loaded;
+        const causeRef = refer(factToRefer);
+
+        // Normalize the value to handle NaN and other non-JSON values
+        // NaN gets serialized to null in JSON, so we normalize it here to ensure
+        // consistent hashing between client and server
+        const normalizedValue = JSON.parse(JSON.stringify(merged.value));
+
         edit.assert({
           ...loaded,
-          is: merged.value,
-          cause: refer(loaded.cause ? normalizeFact(loaded) : loaded),
+          is: normalizedValue,
+          cause: causeRef,
         });
       }
     }
diff --git a/packages/runner/test/conflict-repro.test.ts b/packages/runner/test/conflict-repro.test.ts
new file mode 100644
index 0000000000..7dcbb66e51
--- /dev/null
+++ b/packages/runner/test/conflict-repro.test.ts
@@ -0,0 +1,205 @@
+import { afterEach, beforeEach, describe, it } from "@std/testing/bdd";
+import { expect } from "@std/expect";
+
+import { Identity } from "@commontools/identity";
+import { StorageManager } from "@commontools/runner/storage/cache.deno";
+import { type Cell } from "../src/builder/types.ts";
+import { createBuilder } from "../src/builder/factory.ts";
+import { Runtime } from "../src/runtime.ts";
+import {
+  type IExtendedStorageTransaction,
+  type StorageNotification,
+} from "../src/storage/interface.ts";
+
+const signer = await Identity.fromPassphrase("test conflict");
+const space = signer.did();
+
+interface Item {
+  id?: string;
+}
+
+describe("Conflict Reproduction", () => {
+  let storageManager: ReturnType<typeof StorageManager.emulate>;
+  let runtime: Runtime;
+  let tx: IExtendedStorageTransaction;
+  let lift: ReturnType<typeof createBuilder>["commontools"]["lift"];
+  let recipe: ReturnType<typeof createBuilder>["commontools"]["recipe"];
+  let cell: ReturnType<typeof createBuilder>["commontools"]["cell"];
+  let handler: ReturnType<typeof createBuilder>["commontools"]["handler"];
+  let conflictErrors: Error[];
+
+  beforeEach(() => {
+    conflictErrors = [];
+    storageManager = StorageManager.emulate({ as: signer });
+
+    // Subscribe to storage notifications to capture conflicts
+    storageManager.subscribe({
+      next: (notification: StorageNotification) => {
+        if (
+          notification.type === "revert" &&
+          notification.reason.name === "ConflictError"
+        ) {
+          conflictErrors.push(notification.reason);
+        }
+        return undefined;
+      },
+    });
+
+    runtime = new Runtime({
+      apiUrl: new URL(import.meta.url),
+      storageManager,
+    });
+
+    tx = runtime.edit();
+
+    const { commontools } = createBuilder(runtime);
+    ({ lift, recipe, cell, handler } = commontools);
+  });
+
+  afterEach(async () => {
+    await tx.commit();
+    await runtime?.dispose();
+    await storageManager?.close();
+  });
+
+  it("should NOT have conflicts with lift (fixed)", async () => {
+    const action = handler<
+      undefined,
+      { items: Cell<Item[]>; sequence: Cell<number> }
+    >({}, {
+      type: "object",
+      properties: {
+        items: {
+          type: "array",
+          items: { type: "object", properties: { id: { type: "string" } } },
+          asCell: true,
+        },
+        sequence: { type: "number", asCell: true },
+      },
+      required: ["items", "sequence"],
+    }, (_event, context) => {
+      // Minimal repro: Removing either of these removes the conflict
+      context.items.set([]);
+      context.sequence.set(context.sequence.get() + 1);
+    });
+
+    const conflictRepro = recipe<{ items: Item[] }>(
+      "Conflict Repro",
+      ({ items }) => {
+        const sequence = cell(0);
+
+        // Minimal repro: Removing the lift and the map removes the conflict
+        lift((item: Item[]) => item.map((_) => ({})))(items);
+
+        return {
+          action: action({
+            items,
+            sequence,
+          }),
+          sequence,
+        };
+      },
+    );
+
+    const resultCell = runtime.getCell<{ action: any }>(
+      space,
+      "should reproduce conflict with minimal handler",
+      undefined,
+      tx,
+    );
+    const result = runtime.run(tx, conflictRepro, {
+      items: [{ id: "test" }],
+    }, resultCell);
+    await tx.commit();
+
+    await runtime.idle();
+
+    // This tests the condition that caused the conflict
+    expect(result.get().sequence).toBe(undefined);
+
+    // Trigger the handler
+    result.key("action").send({});
+    await runtime.idle();
+
+    // This tests the condition that caused the conflict
+    expect(result.get().sequence).toBe(null);
+
+    // Give time for async conflict notifications to be processed
+    // The conflict happens during the optimistic transaction retry,
+    // which completes asynchronously after runtime.idle()
+    await new Promise((resolve) => setTimeout(resolve, 100));
+
+    // Verify that conflicts were NOT captured (fixed by normalizing NaN to null)
+    expect(conflictErrors.length).toBe(0);
+  });
+
+  it("should NOT have conflicts without lift", async () => {
+    conflictErrors = []; // Reset
+
+    const action = handler<
+      undefined,
+      { items: Cell<Item[]>; sequence: Cell<number> }
+    >({}, {
+      type: "object",
+      properties: {
+        items: {
+          type: "array",
+          items: { type: "object", properties: { id: { type: "string" } } },
+          asCell: true,
+        },
+        sequence: { type: "number", asCell: true },
+      },
+      required: ["items", "sequence"],
+    }, (_event, context) => {
+      // Same handler logic
+      context.items.set([]);
+      context.sequence.set(context.sequence.get() + 1);
+    });
+
+    const conflictReproNoLift = recipe<{ items: Item[] }>(
+      "Conflict Repro No Lift",
+      ({ items }) => {
+        const sequence = cell(0);
+
+        // NO lift - this should eliminate conflicts
+
+        return {
+          action: action({
+            items,
+            sequence,
+          }),
+          sequence,
+        };
+      },
+    );
+
+    const resultCell = runtime.getCell<{ action: any }>(
+      space,
+      "should NOT have conflicts without lift",
+      undefined,
+      tx,
+    );
+    const result = runtime.run(tx, conflictReproNoLift, {
+      items: [{ id: "test" }],
+    }, resultCell);
+    await tx.commit();
+
+    await runtime.idle();
+
+    // This tests the condition that caused the conflict
+    expect(result.get().sequence).toBe(undefined);
+
+    // Trigger the handler
+    result.key("action").send({});
+    await runtime.idle();
+
+    // This tests the condition that caused the conflict
+    expect(result.get().sequence).toBe(null);
+
+    // Give time for async conflict notifications
+    await new Promise((resolve) => setTimeout(resolve, 100));
+
+    // Verify that NO conflicts were captured
+    expect(conflictErrors.length).toBe(0);
+  });
+});