diff --git a/tests/multi_contract_isolation.rs b/tests/multi_contract_isolation.rs
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+//! # Multi-Contract State Isolation Integration Test
+//!
+//! This test deploys two independent `VeroContract` instances within the same
+//! Soroban test environment and verifies that their instance storage is fully
+//! isolated — guardian state, reputation scores, and task records registered
+//! on one instance are invisible to the other.
+//!
+//! ## Why this matters
+//!
+//! All contract state lives in **instance storage** scoped to the contract
+//! deployment address (per `README.md`'s Storage Design section). While
+//! instance-storage isolation is a Soroban platform guarantee, a future
+//! refactor that accidentally uses `persistent` or `temporary` storage with
+//! a global key would silently break that guarantee. This test exercises the
+//! boundary so such regressions surface immediately in CI.
+//!
+//! ## What is tested (acceptance criteria from issue #169)
+//!
+//! | Dimension       | Contract A action              | Contract B assertion           |
+//! |-----------------|--------------------------------|--------------------------------|
+//! | Guardian state  | `add_guardian(guardian_a)`     | `is_guardian(guardian_a)` → false |
+//! | Reputation      | `set_reputation(guardian_a, 500)` | `get_reputation(guardian_a)` → None |
+//! | Task state      | `register_task(task_id=1)`     | `get_task(1)` → None           |
+//! | Reverse check   | *(nothing added to B)*         | B's own guardian/task absent from A |
+
+#![cfg(test)]
+
+use soroban_sdk::{testutils::Address as _, Address, Env};
+use vero_core_contracts::{Role, VeroContract, VeroContractClient};
+
+// ─── Helpers ─────────────────────────────────────────────────────────────────
+
+/// Deploy a fresh `VeroContract` instance, initialize it with the given admin
+/// and token, grant `GuardianManager` and `TaskManager` to the admin, and
+/// return a ready-to-use client.
+fn deploy_instance<'a>(
+    env: &'a Env,
+    admin: &Address,
+    token_addr: &Address,
+    lock_threshold: i128,
+) -> VeroContractClient<'a> {
+    let contract_id = env.register_contract(None, VeroContract);
+    let client = VeroContractClient::new(env, &contract_id);
+
+    client.initialize(admin, token_addr, &lock_threshold);
+    client.grant_role(admin, admin, &Role::GuardianManager);
+    client.grant_role(admin, admin, &Role::TaskManager);
+
+    client
+}
+
+// ─── Tests ───────────────────────────────────────────────────────────────────
+
+/// Deploy two contract instances backed by the same token (realistic: they
+/// could share a token contract), configure one with a guardian and a task,
+/// and assert the other knows nothing about either.
+#[test]
+fn test_guardian_state_does_not_leak_between_instances() {
+    let env = Env::default();
+    env.mock_all_auths();
+
+    // Two independent admins, one shared token.
+    let admin_a = Address::generate(&env);
+    let admin_b = Address::generate(&env);
+    let token_admin = Address::generate(&env);
+    let token = env.register_stellar_asset_contract_v2(token_admin);
+    let token_addr = token.address();
+
+    let client_a = deploy_instance(&env, &admin_a, &token_addr, 1);
+    let client_b = deploy_instance(&env, &admin_b, &token_addr, 1);
+
+    // ── Populate contract A ──────────────────────────────────────────────────
+    let guardian_a = Address::generate(&env);
+    client_a.add_guardian(&admin_a, &guardian_a);
+    client_a.set_reputation(&admin_a, &guardian_a, &500u64);
+
+    let task_id_a: u64 = 1;
+    client_a.register_task(&admin_a, &task_id_a, &1u32);
+
+    // ── Contract A — sanity-check that A's own state is readable ────────────
+    assert!(
+        client_a.is_guardian(&guardian_a),
+        "A: guardian_a should be registered in instance A"
+    );
+    assert_eq!(
+        client_a.get_reputation(&guardian_a),
+        Some(500),
+        "A: reputation for guardian_a should be 500 in instance A"
+    );
+    assert!(
+        client_a.get_task(&task_id_a).is_some(),
+        "A: task 1 should exist in instance A"
+    );
+
+    // ── Contract B — assert complete isolation ───────────────────────────────
+    assert!(
+        !client_b.is_guardian(&guardian_a),
+        "B: guardian_a must NOT appear as a guardian in instance B (storage leak!)"
+    );
+    assert_eq!(
+        client_b.get_reputation(&guardian_a),
+        None,
+        "B: reputation for guardian_a must be None in instance B (storage leak!)"
+    );
+    assert!(
+        client_b.get_task(&task_id_a).is_none(),
+        "B: task 1 must NOT exist in instance B (storage leak!)"
+    );
+}
+
+/// Mirror of the previous test: populate B and verify A is unaffected.
+/// Together the two tests confirm bidirectional isolation.
+#[test]
+fn test_state_registered_in_b_does_not_appear_in_a() {
+    let env = Env::default();
+    env.mock_all_auths();
+
+    let admin_a = Address::generate(&env);
+    let admin_b = Address::generate(&env);
+    let token_admin = Address::generate(&env);
+    let token = env.register_stellar_asset_contract_v2(token_admin);
+    let token_addr = token.address();
+
+    let client_a = deploy_instance(&env, &admin_a, &token_addr, 1);
+    let client_b = deploy_instance(&env, &admin_b, &token_addr, 1);
+
+    // ── Populate contract B ──────────────────────────────────────────────────
+    let guardian_b = Address::generate(&env);
+    client_b.add_guardian(&admin_b, &guardian_b);
+    client_b.set_reputation(&admin_b, &guardian_b, &999u64);
+
+    let task_id_b: u64 = 42;
+    client_b.register_task(&admin_b, &task_id_b, &1u32);
+
+    // ── Contract B — sanity-check ────────────────────────────────────────────
+    assert!(client_b.is_guardian(&guardian_b));
+    assert_eq!(client_b.get_reputation(&guardian_b), Some(999));
+    assert!(client_b.get_task(&task_id_b).is_some());
+
+    // ── Contract A — must have no knowledge of B's state ────────────────────
+    assert!(
+        !client_a.is_guardian(&guardian_b),
+        "A: guardian_b must NOT appear in instance A (storage leak!)"
+    );
+    assert_eq!(
+        client_a.get_reputation(&guardian_b),
+        None,
+        "A: reputation for guardian_b must be None in instance A (storage leak!)"
+    );
+    assert!(
+        client_a.get_task(&task_id_b).is_none(),
+        "A: task 42 must NOT exist in instance A (storage leak!)"
+    );
+}
+
+/// Verify that each instance maintains an independent admin: the admin of A
+/// cannot be read back as the admin of B, confirming that even initialisation
+/// state is fully scoped to each deployment.
+#[test]
+fn test_admin_state_is_isolated_per_instance() {
+    let env = Env::default();
+    env.mock_all_auths();
+
+    let admin_a = Address::generate(&env);
+    let admin_b = Address::generate(&env);
+    let token_admin = Address::generate(&env);
+    let token = env.register_stellar_asset_contract_v2(token_admin);
+    let token_addr = token.address();
+
+    let client_a = deploy_instance(&env, &admin_a, &token_addr, 1);
+    let client_b = deploy_instance(&env, &admin_b, &token_addr, 1);
+
+    // Each instance stores its own admin.
+    assert_eq!(
+        client_a.get_admin(),
+        Some(admin_a.clone()),
+        "A: get_admin should return admin_a"
+    );
+    assert_eq!(
+        client_b.get_admin(),
+        Some(admin_b.clone()),
+        "B: get_admin should return admin_b"
+    );
+
+    // Cross-check: A's admin is not B's admin and vice-versa.
+    assert_ne!(
+        client_a.get_admin(),
+        client_b.get_admin(),
+        "admin addresses must differ between the two instances"
+    );
+}
+
+/// Full end-to-end isolation: both instances are populated with overlapping
+/// task IDs and guardian addresses, and we assert neither can see the other's
+/// entries.
+#[test]
+fn test_overlapping_task_ids_are_isolated_per_instance() {
+    let env = Env::default();
+    env.mock_all_auths();
+
+    let admin_a = Address::generate(&env);
+    let admin_b = Address::generate(&env);
+    let token_admin = Address::generate(&env);
+    let token = env.register_stellar_asset_contract_v2(token_admin);
+    let token_addr = token.address();
+
+    let client_a = deploy_instance(&env, &admin_a, &token_addr, 1);
+    let client_b = deploy_instance(&env, &admin_b, &token_addr, 1);
+
+    // Both instances register the SAME task id (100) independently.
+    let shared_task_id: u64 = 100;
+    client_a.register_task(&admin_a, &shared_task_id, &1u32);
+    client_b.register_task(&admin_b, &shared_task_id, &2u32);
+
+    // Task exists in both, but with the min_votes_required each was given.
+    let task_in_a = client_a.get_task(&shared_task_id).unwrap();
+    let task_in_b = client_b.get_task(&shared_task_id).unwrap();
+
+    assert_eq!(task_in_a.min_votes_required, 1, "A: min_votes should be 1");
+    assert_eq!(task_in_b.min_votes_required, 2, "B: min_votes should be 2");
+
+    // The records are independent — same key, different storage namespaces.
+    assert_ne!(
+        task_in_a.min_votes_required, task_in_b.min_votes_required,
+        "tasks with the same id must hold independent state in each instance"
+    );
+
+    // Both instances register the SAME guardian address with different reputations.
+    let shared_guardian = Address::generate(&env);
+    client_a.add_guardian(&admin_a, &shared_guardian);
+    client_b.add_guardian(&admin_b, &shared_guardian);
+
+    client_a.set_reputation(&admin_a, &shared_guardian, &100u64);
+    client_b.set_reputation(&admin_b, &shared_guardian, &200u64);
+
+    assert_eq!(
+        client_a.get_reputation(&shared_guardian),
+        Some(100),
+        "A: shared_guardian reputation must be 100 in instance A"
+    );
+    assert_eq!(
+        client_b.get_reputation(&shared_guardian),
+        Some(200),
+        "B: shared_guardian reputation must be 200 in instance B"
+    );
+}
+
+/// Verify that pause / circuit-breaker state is also isolated: pausing instance
+/// A must not affect the operational status of instance B.
+#[test]
+fn test_pause_state_is_isolated_per_instance() {
+    let env = Env::default();
+    env.mock_all_auths();
+
+    let admin_a = Address::generate(&env);
+    let admin_b = Address::generate(&env);
+    let token_admin = Address::generate(&env);
+    let token = env.register_stellar_asset_contract_v2(token_admin);
+    let token_addr = token.address();
+
+    let client_a = deploy_instance(&env, &admin_a, &token_addr, 1);
+    let client_b = deploy_instance(&env, &admin_b, &token_addr, 1);
+
+    // Grant EmergencyManager role so admin_a can pause instance A.
+    client_a.grant_role(&admin_a, &admin_a, &Role::EmergencyManager);
+
+    // Both instances start unpaused.
+    assert!(!client_a.is_paused(), "A: should not be paused initially");
+    assert!(!client_b.is_paused(), "B: should not be paused initially");
+
+    // Pause only instance A.
+    client_a.pause(&admin_a);
+
+    // Instance A is paused; instance B must remain operational.
+    assert!(client_a.is_paused(), "A: must be paused after pause()");
+    assert!(
+        !client_b.is_paused(),
+        "B: must NOT be paused — pause on A must not leak into B (storage leak!)"
+    );
+}