diff --git a/.kiro/specs/raft-library/tasks.md b/.kiro/specs/raft-library/tasks.md
index abdfcfb..09bfbc2 100644
--- a/.kiro/specs/raft-library/tasks.md
+++ b/.kiro/specs/raft-library/tasks.md
@@ -102,7 +102,7 @@
   - All 10 Unity test cases pass; `raft_sim_dump_log` confirms correct event sequence for A2
   - _Requirements: 2.1, 2.2, 2.3, 3.1, 3.2, 3.3, 3.5, 8.2, 8.3_
 
-- [ ] 5.2 Test Groups C and H: on_vote_eligible policy and persistence/restart (11 cases)
+- [x] 5.2 Test Groups C and H: on_vote_eligible policy and persistence/restart (11 cases)
   - C1: all Raft invariants pass, `on_vote_eligible` returns 0 → denied
   - C2: all Raft invariants pass, `on_vote_eligible` returns 1 → granted
   - C3: `on_vote_eligible` is NULL at init → eligible candidates granted when Raft invariants pass
diff --git a/src/lib/testsuite/test_raft.c b/src/lib/testsuite/test_raft.c
index c264ed3..1e26117 100644
--- a/src/lib/testsuite/test_raft.c
+++ b/src/lib/testsuite/test_raft.c
@@ -1829,6 +1829,340 @@ static void test_proto_A5_leader_denies_vote_request(void)
     TEST_ASSERT_EQUAL_INT(lc_before, c.leader_count);
 }
 
+/* ---------- Group C: on_vote_eligible policy callback (task 5.2) ---------- */
+
+/*
+ * test_proto_C1_eligible_denies
+ *
+ * on_vote_eligible returns 0 → RAFT_DENY, voted_for unchanged (-1),
+ * vote_eligible_call_count == 1.
+ */
+static void test_proto_C1_eligible_denies(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    cbs.on_vote_eligible = mock_vote_eligible;
+    reset_mock();
+    g_mock.vote_eligible_return_value = 0; /* deny */
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 1;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 1, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_DENY, rc);
+    TEST_ASSERT_EQUAL_INT(-1, s.voted_for);
+    TEST_ASSERT_EQUAL_INT(1, g_mock.vote_eligible_call_count);
+}
+
+/*
+ * test_proto_C2_eligible_grants
+ *
+ * on_vote_eligible returns 1 → RAFT_GRANT, voted_for==1,
+ * vote_eligible_call_count == 1.
+ */
+static void test_proto_C2_eligible_grants(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    cbs.on_vote_eligible = mock_vote_eligible;
+    reset_mock();
+    g_mock.vote_eligible_return_value = 1; /* grant */
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 1;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 1, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_GRANT, rc);
+    TEST_ASSERT_EQUAL_INT(1, s.voted_for);
+    TEST_ASSERT_EQUAL_INT(1, g_mock.vote_eligible_call_count);
+}
+
+/*
+ * test_proto_C3_eligible_null_grants
+ *
+ * on_vote_eligible is NULL (default make_mock_cbs) → treated as eligible,
+ * grant succeeds (RAFT_GRANT).
+ */
+static void test_proto_C3_eligible_null_grants(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    /* on_vote_eligible left NULL in make_mock_cbs */
+    reset_mock();
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 1;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 1, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_GRANT, rc);
+    /* vote_eligible not called (NULL) */
+    TEST_ASSERT_EQUAL_INT(0, g_mock.vote_eligible_call_count);
+}
+
+/*
+ * test_proto_C4_stale_term_no_eligible_call
+ *
+ * Node at term=5, receives request at term=3 (stale).
+ * The stale-term check must return DENY before the policy gate is reached.
+ * vote_eligible_call_count must be 0.
+ */
+static void test_proto_C4_stale_term_no_eligible_call(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    cbs.on_vote_eligible = mock_vote_eligible;
+    reset_mock();
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 5;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 3, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_DENY, rc);
+    TEST_ASSERT_EQUAL_INT(0, g_mock.vote_eligible_call_count);
+}
+
+/*
+ * test_proto_C5_already_voted_no_eligible_call
+ *
+ * voted_for=1, voted_for_term=3 at term=3.
+ * Receives request from idx=2 at term=3.
+ * The dup-vote check must fire before the policy gate.
+ * vote_eligible_call_count must be 0.
+ */
+static void test_proto_C5_already_voted_no_eligible_call(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    cbs.on_vote_eligible = mock_vote_eligible;
+    reset_mock();
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term           = 3;
+    s.voted_for      = 1;
+    s.voted_for_term = 3;
+
+    int rc = raft_on_vote_request(&s, 2, 3, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_DENY, rc);
+    TEST_ASSERT_EQUAL_INT(0, g_mock.vote_eligible_call_count);
+}
+
+/* ---------- Group H: Persistence and restart (task 5.2) ---------- */
+
+/*
+ * test_proto_H1_init_with_persisted_state
+ *
+ * raft_config_t with initial_term=5, initial_voted_for=1.
+ * After raft_init: s.term==5, s.voted_for==1, s.role==RAFT_FOLLOWER.
+ */
+static void test_proto_H1_init_with_persisted_state(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    raft_config_t    cfg;
+
+    memset(&s, 0, sizeof(s));
+    memset(&cfg, 0, sizeof(cfg));
+    cfg.n_peers             = 3;
+    cfg.self_idx            = 0;
+    cfg.election_timeout_ms = 1000;
+    cfg.initial_term        = 5;
+    cfg.initial_voted_for   = 1;
+    cfg.cbs                 = &cbs;
+
+    int rc = raft_init(&s, &cfg);
+
+    TEST_ASSERT_EQUAL_INT(0, rc);
+    TEST_ASSERT_EQUAL_UINT64(5, s.term);
+    TEST_ASSERT_EQUAL_INT(1, s.voted_for);
+    TEST_ASSERT_EQUAL_INT(RAFT_FOLLOWER, s.role);
+}
+
+/*
+ * test_proto_H2_init_first_boot
+ *
+ * initial_term=0, initial_voted_for=-1 (first boot).
+ * After raft_init: s.term==0, s.voted_for==-1, s.role==RAFT_FOLLOWER.
+ */
+static void test_proto_H2_init_first_boot(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    raft_config_t    cfg;
+
+    memset(&s, 0, sizeof(s));
+    memset(&cfg, 0, sizeof(cfg));
+    cfg.n_peers             = 3;
+    cfg.self_idx            = 0;
+    cfg.election_timeout_ms = 1000;
+    cfg.initial_term        = 0;
+    cfg.initial_voted_for   = -1;
+    cfg.cbs                 = &cbs;
+
+    int rc = raft_init(&s, &cfg);
+
+    TEST_ASSERT_EQUAL_INT(0, rc);
+    TEST_ASSERT_EQUAL_UINT64(0, s.term);
+    TEST_ASSERT_EQUAL_INT(-1, s.voted_for);
+    TEST_ASSERT_EQUAL_INT(RAFT_FOLLOWER, s.role);
+}
+
+/*
+ * test_proto_H3_persist_before_vote_recorded
+ *
+ * Verify that on_persist fires BEFORE voted_for is written to raft_state_t.
+ * A custom persist callback captures s->voted_for at call time; it must
+ * still be -1 (unset) when persist is invoked, and set to the candidate
+ * after raft_on_vote_request returns RAFT_GRANT.
+ */
+static raft_state_t *h3_state_ptr         = NULL;
+static int           h3_voted_for_snapshot = 999; /* sentinel; updated by h3_persist */
+
+static int h3_persist(void *ctx, uint64_t term, int voted_for)
+{
+    (void)ctx; (void)term; (void)voted_for;
+    /* Capture voted_for from the live state object at persist call time */
+    if (h3_state_ptr)
+        h3_voted_for_snapshot = h3_state_ptr->voted_for;
+    g_mock.persist_count++;
+    return 0;
+}
+
+static void test_proto_H3_persist_before_vote_recorded(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    reset_mock();
+    h3_state_ptr         = &s;
+    h3_voted_for_snapshot = 999; /* reset sentinel */
+    cbs.on_persist       = h3_persist;
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 1;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 1, &reply_term);
+
+    /* Must grant */
+    TEST_ASSERT_EQUAL_INT(RAFT_GRANT, rc);
+
+    /* on_persist must have fired once */
+    TEST_ASSERT_EQUAL_INT(1, g_mock.persist_count);
+
+    /* At persist call time, voted_for must still have been -1 (not yet written) */
+    TEST_ASSERT_EQUAL_INT(-1, h3_voted_for_snapshot);
+
+    /* After the call returns, voted_for must be set to from_idx=1 */
+    TEST_ASSERT_EQUAL_INT(1, s.voted_for);
+
+    h3_state_ptr = NULL;
+}
+
+/*
+ * test_proto_H4_persist_fail_denies
+ *
+ * g_mock.persist_return_value = -1.
+ * raft_on_vote_request must return RAFT_DENY and leave voted_for==-1.
+ */
+static void test_proto_H4_persist_fail_denies(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    uint64_t         reply_term = 0;
+
+    reset_mock();
+    g_mock.persist_return_value = -1;
+
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+    s.term      = 1;
+    s.voted_for = -1;
+
+    int rc = raft_on_vote_request(&s, 1, 1, &reply_term);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_DENY, rc);
+    TEST_ASSERT_EQUAL_INT(-1, s.voted_for);
+}
+
+/*
+ * test_proto_H5_start_election_self_vote_persisted
+ *
+ * raft_start_election(s) for a 3-node cluster.
+ * on_persist must fire with (new_term=1, self_idx=0).
+ * g_mock.last_persist_voted_for == s.self_idx (0).
+ * g_mock.last_persist_term == 1.
+ */
+static void test_proto_H5_start_election_self_vote_persisted(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+
+    reset_mock();
+    TEST_ASSERT_EQUAL_INT(0, init_node(&s, &cbs, 3, 0));
+
+    int rc = raft_start_election(&s);
+
+    TEST_ASSERT_EQUAL_INT(RAFT_OK, rc);
+
+    /* on_persist fired with (term=1, self_idx=0) for the self-vote */
+    TEST_ASSERT_EQUAL_INT(1, g_mock.persist_count);
+    TEST_ASSERT_EQUAL_UINT64(1, g_mock.last_persist_term);
+    TEST_ASSERT_EQUAL_INT(s.self_idx, g_mock.last_persist_voted_for);
+    TEST_ASSERT_EQUAL_INT(0, g_mock.last_persist_voted_for);
+}
+
+/*
+ * test_proto_Hnull_required_callback_einval
+ *
+ * raft_init with NULL on_become_follower → returns -EINVAL.
+ * State remains untouched (canary check).
+ */
+static void test_proto_Hnull_required_callback_einval(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+    raft_config_t    cfg;
+
+    memset(&s, 0xAB, sizeof(s));
+
+    cbs.on_become_follower = NULL; /* knock out a required callback */
+
+    memset(&cfg, 0, sizeof(cfg));
+    cfg.n_peers  = 3;
+    cfg.self_idx = 0;
+    cfg.cbs      = &cbs;
+
+    int rc = raft_init(&s, &cfg);
+
+    TEST_ASSERT_EQUAL_INT(-EINVAL, rc);
+
+    /* s must be completely unchanged (canary check) */
+    {
+        unsigned char buf[sizeof(s)];
+        memset(buf, 0xAB, sizeof(buf));
+        TEST_ASSERT_EQUAL_MEMORY(buf, &s, sizeof(s));
+    }
+}
+
 /* ---------- Group B: voted_for Invariant (task 5.1) ---------- */
 
 /*
@@ -2065,5 +2399,20 @@ void test_raft(void)
     RUN_TEST(test_proto_B3_stale_term_denied);
     RUN_TEST(test_proto_B4_different_candidate_denied);
     RUN_TEST(test_proto_B5_idempotent_same_candidate);
+
+    /* Group C: on_vote_eligible policy callback (task 5.2) */
+    RUN_TEST(test_proto_C1_eligible_denies);
+    RUN_TEST(test_proto_C2_eligible_grants);
+    RUN_TEST(test_proto_C3_eligible_null_grants);
+    RUN_TEST(test_proto_C4_stale_term_no_eligible_call);
+    RUN_TEST(test_proto_C5_already_voted_no_eligible_call);
+
+    /* Group H: Persistence and restart (task 5.2) */
+    RUN_TEST(test_proto_H1_init_with_persisted_state);
+    RUN_TEST(test_proto_H2_init_first_boot);
+    RUN_TEST(test_proto_H3_persist_before_vote_recorded);
+    RUN_TEST(test_proto_H4_persist_fail_denies);
+    RUN_TEST(test_proto_H5_start_election_self_vote_persisted);
+    RUN_TEST(test_proto_Hnull_required_callback_einval);
 #endif
 }