diff --git a/.changeset/policy-transactional-visibility.md b/.changeset/policy-transactional-visibility.md
new file mode 100644
index 0000000000..d238d09683
--- /dev/null
+++ b/.changeset/policy-transactional-visibility.md
@@ -0,0 +1,5 @@
+---
+"@executor-js/sdk": patch
+---
+
+Wrap tool-policy create and update in a transaction so concurrent edits can no longer read the same snapshot and commit duplicate positions or overwrite each other.
diff --git a/packages/core/sdk/src/executor.ts b/packages/core/sdk/src/executor.ts
index aba6b674c2..51c58b5cd5 100644
--- a/packages/core/sdk/src/executor.ts
+++ b/packages/core/sdk/src/executor.ts
@@ -5396,30 +5396,35 @@ export const createExecutor = <const TPlugins extends readonly AnyPlugin[] = rea
           try: () => ownedKeys(input.owner),
           catch: (cause) => storageFailureFromUnknown("invalid owner", cause),
         });
-        const existing = yield* core.findMany("tool_policy", {
-          where: byOwner(input.owner),
-        });
-        // Default placement is specificity-aware (below any more-specific
-        // rule), not top-of-list: a client that omits position — the UI when
-        // its policy list is stale, the API, an agent tool — must not have its
-        // broad rule silently shadow an existing narrow one.
-        const position = input.position ?? positionForNewPattern(input.pattern, existing);
-        const id = PolicyId.make(
-          `pol_${Math.random().toString(36).slice(2)}${Date.now().toString(36)}`,
+        // Scan → position → insert runs atomically so concurrent creates cannot commit duplicate positions.
+        return yield* transaction(
+          Effect.gen(function* () {
+            const existing = yield* core.findMany("tool_policy", {
+              where: byOwner(input.owner),
+            });
+            // Default placement is specificity-aware (below any more-specific
+            // rule), not top-of-list: a client that omits position — the UI
+            // when its policy list is stale, the API, an agent tool — must
+            // not have its broad rule silently shadow an existing narrow one.
+            const position = input.position ?? positionForNewPattern(input.pattern, existing);
+            const id = PolicyId.make(
+              `pol_${Math.random().toString(36).slice(2)}${Date.now().toString(36)}`,
+            );
+            const now = new Date();
+            const created = yield* core.create("tool_policy", {
+              tenant: keys.tenant,
+              owner: keys.owner,
+              subject: keys.subject,
+              id: String(id),
+              pattern: input.pattern,
+              action: input.action,
+              position,
+              created_at: now,
+              updated_at: now,
+            });
+            return rowToToolPolicy(created);
+          }),
         );
-        const now = new Date();
-        const created = yield* core.create("tool_policy", {
-          tenant: keys.tenant,
-          owner: keys.owner,
-          subject: keys.subject,
-          id: String(id),
-          pattern: input.pattern,
-          action: input.action,
-          position,
-          created_at: now,
-          updated_at: now,
-        });
-        return rowToToolPolicy(created);
       });
 
     const policiesUpdate = (
@@ -5433,20 +5438,25 @@ export const createExecutor = <const TPlugins extends readonly AnyPlugin[] = rea
           });
         }
         const where = (b: AnyCb) => b.and(byOwner(input.owner)(b), b("id", "=", input.id));
-        const existing = yield* core.findFirst("tool_policy", { where });
-        if (!existing) {
-          return yield* new StorageError({
-            message: `Tool policy not found: ${input.id}`,
-            cause: undefined,
-          });
-        }
-        const set: Record<string, unknown> = { updated_at: new Date() };
-        if (input.pattern !== undefined) set.pattern = input.pattern;
-        if (input.action !== undefined) set.action = input.action;
-        if (input.position !== undefined) set.position = input.position;
-        yield* core.updateMany("tool_policy", { where, set });
-        const updated = yield* core.findFirst("tool_policy", { where });
-        return rowToToolPolicy(updated ?? ({ ...existing, ...set } as ToolPolicyRow));
+        // Existence check, write, and re-read commit together.
+        return yield* transaction(
+          Effect.gen(function* () {
+            const existing = yield* core.findFirst("tool_policy", { where });
+            if (!existing) {
+              return yield* new StorageError({
+                message: `Tool policy not found: ${input.id}`,
+                cause: undefined,
+              });
+            }
+            const set: Record<string, unknown> = { updated_at: new Date() };
+            if (input.pattern !== undefined) set.pattern = input.pattern;
+            if (input.action !== undefined) set.action = input.action;
+            if (input.position !== undefined) set.position = input.position;
+            yield* core.updateMany("tool_policy", { where, set });
+            const updated = yield* core.findFirst("tool_policy", { where });
+            return rowToToolPolicy(updated ?? ({ ...existing, ...set } as ToolPolicyRow));
+          }),
+        );
       });
 
     const policiesRemove = (input: RemoveToolPolicyInput): Effect.Effect<void, StorageFailure> =>
diff --git a/packages/core/sdk/src/policies.test.ts b/packages/core/sdk/src/policies.test.ts
index beb9703c49..c05e634842 100644
--- a/packages/core/sdk/src/policies.test.ts
+++ b/packages/core/sdk/src/policies.test.ts
@@ -428,6 +428,23 @@ describe("executor.policies", () => {
     }),
   );
 
+  it.live("concurrent creates of equally specific rules get distinct positions", () =>
+    Effect.gen(function* () {
+      const executor = yield* setupExecutor();
+      yield* Effect.all(
+        [
+          executor.policies.create({ owner: "org", pattern: "vercel.dns.create", action: "block" }),
+          executor.policies.create({ owner: "org", pattern: "vercel.dns.delete", action: "block" }),
+        ],
+        { concurrency: "unbounded" },
+      );
+
+      const rules = yield* executor.policies.list();
+      expect(rules).toHaveLength(2);
+      expect(new Set(rules.map((r) => r.position)).size).toBe(2);
+    }),
+  );
+
   it.effect("create stores rules at the requested owner", () =>
     Effect.gen(function* () {
       const executor = yield* setupExecutor();