diff --git a/.changeset/fix-landlord-maxretries.md b/.changeset/fix-landlord-maxretries.md
new file mode 100644
index 0000000..536a431
--- /dev/null
+++ b/.changeset/fix-landlord-maxretries.md
@@ -0,0 +1,5 @@
+---
+"landlord": patch
+---
+
+Validate `maxRetries` on a contract as a positive integer. It was previously an unconstrained `z.number()`, so negative or zero values silently caused a tenant to escalate without ever running, and fractional values produced an unexpected extra attempt in the `attempt < maxRetries` loop. The schema now enforces `int().min(1)`.
diff --git a/packages/landlord/src/contract.ts b/packages/landlord/src/contract.ts
index 295cff5..4c6f0e5 100644
--- a/packages/landlord/src/contract.ts
+++ b/packages/landlord/src/contract.ts
@@ -16,7 +16,7 @@ export const ContractSchema = z.object({
   toolsAllowed: z.array(z.string()).optional(),
   toolsDenied: z.array(z.string()).optional(),
   dependsOn: z.array(z.string()).default([]),
-  maxRetries: z.number().default(3),
+  maxRetries: z.number().int().min(1).default(3),
 });
 
 export type Checkpoint = z.infer<typeof CheckpointSchema>;
diff --git a/packages/landlord/test/contract.test.ts b/packages/landlord/test/contract.test.ts
index a4c80f4..969b2d0 100644
--- a/packages/landlord/test/contract.test.ts
+++ b/packages/landlord/test/contract.test.ts
@@ -63,4 +63,19 @@ describe('ContractSchema', () => {
     });
     expect(result.success).toBe(false);
   });
+
+  it('rejects non-positive, non-integer, and fractional maxRetries', () => {
+    const base = {
+      role: 'r',
+      objective: 'x',
+      subPrompt: 'x',
+      checkpoints: [],
+      outputSchema: {},
+    };
+    for (const maxRetries of [0, -1, 2.5]) {
+      const result = ContractSchema.safeParse({ ...base, maxRetries });
+      expect(result.success).toBe(false);
+    }
+    expect(ContractSchema.safeParse({ ...base, maxRetries: 1 }).success).toBe(true);
+  });
 });