feat(raft-log-replication): init leader progress on becoming leader (task 2.2)

next_index[j]=log_len+1, match_index[j]=0 for every peer at both win paths
(single-node RAFT_ELECTED_IMMEDIATELY in raft_start_election; multi-node
RAFT_BECAME_LEADER in raft_on_vote_reply) via shared raft_init_leader_progress
helper (raft.tla BecomeLeader, Req 3.1). Suite green under ASAN.

.kiro/specs/raft-log-replication/tasks.md

@@ -39,7 +39,7 @@
   - _Boundary: raft.c, test_raft.c_
   - _Depends: 1.3_
 
-- [ ] 2.2 RED+GREEN: leader progress initialized on becoming leader
+- [x] 2.2 RED+GREEN: leader progress initialized on becoming leader
   - Test: after a node becomes leader, `next_index[j] == log_len + 1` and `match_index[j] == 0` for every peer (raft.tla BecomeLeader)
   - Implement the `next_index`/`match_index` initialization on the win path (`raft_start_election` single-node + the multi-node become-leader transition)
   - Observable completion: assertion on `next_index`/`match_index` after election passes; no regression in election tests

src/lib/raft/raft.c

@@ -74,6 +74,16 @@ int raft_init(raft_state_t *s, const raft_config_t *cfg)
     return 0;
 }
 
+/* Initialize per-peer leader progress on becoming leader (raft.tla BecomeLeader,
+ * Req 3.1): next_index[j] = log_len + 1, match_index[j] = 0 for every peer j. */
+static void raft_init_leader_progress(raft_state_t *s)
+{
+    for (int j = 0; j < s->n_peers; j++) {
+        s->next_index[j]  = s->log_len + 1;
+        s->match_index[j] = 0;
+    }
+}
+
 int raft_start_election(raft_state_t *s)
 {
     /* Guard: reject if already CANDIDATE or LEADER */
@@ -103,6 +113,7 @@ int raft_start_election(raft_state_t *s)
     if (s->n_peers == 1) {
         s->role             = RAFT_LEADER;
         s->election_decided = 1;
+        raft_init_leader_progress(s);
         s->cbs->on_become_leader(s->ctx, s->term);
         return RAFT_ELECTED_IMMEDIATELY;
     }
@@ -389,6 +400,7 @@ int raft_on_vote_reply(raft_state_t *s, int from_idx, int granted, uint64_t term
     if (s->votes_granted >= quorum) {
         s->role             = RAFT_LEADER;
         s->election_decided = 1;
+        raft_init_leader_progress(s);
         s->cbs->on_become_leader(s->ctx, s->term);
         s->cbs->on_cancel_timeout(s->ctx);
         if (s->cbs->on_trace)

src/lib/testsuite/test_raft.c

@@ -1416,6 +1416,78 @@ static void test_vote_reply_pending_waiting(void)
     TEST_ASSERT_EQUAL_INT(0, g_mock.cancel_timeout_count);
 }
 
+/* ---------- leader progress init on becoming leader (task 2.2) ---------- */
+
+/* Init a node with a non-zero restored log length (initial_log_len). */
+static int init_node_log_len(raft_state_t *s, raft_callbacks_t *cbs,
+                             int n_peers, int self_idx, uint64_t initial_log_len)
+{
+    raft_config_t cfg;
+    memset(&cfg, 0, sizeof(cfg));
+    cfg.n_peers             = n_peers;
+    cfg.self_idx            = self_idx;
+    cfg.election_timeout_ms = 1000;
+    cfg.initial_log_len     = initial_log_len;
+    cfg.cbs                 = cbs;
+    return raft_init(s, &cfg);
+}
+
+/*
+ * test_leader_progress_init_single_node (raft.tla BecomeLeader, Req 3.1)
+ *
+ * Single-node immediate-win path (raft_start_election → RAFT_ELECTED_IMMEDIATELY).
+ * Non-zero restored log (log_len=4): on becoming leader, next_index[j] must equal
+ * log_len+1 (=5) and match_index[j] must equal 0 for EVERY peer j in [0, n_peers).
+ */
+static void test_leader_progress_init_single_node(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+
+    reset_mock();
+    TEST_ASSERT_EQUAL_INT(0, init_node_log_len(&s, &cbs, 1, 0, 4));
+    TEST_ASSERT_EQUAL_UINT64(4, s.log_len);
+
+    int rc = raft_start_election(&s);
+    TEST_ASSERT_EQUAL_INT(RAFT_ELECTED_IMMEDIATELY, rc);
+    TEST_ASSERT_EQUAL_INT(RAFT_LEADER, s.role);
+
+    for (int j = 0; j < s.n_peers; j++) {
+        TEST_ASSERT_EQUAL_UINT64(s.log_len + 1, s.next_index[j]);
+        TEST_ASSERT_EQUAL_UINT64(0, s.match_index[j]);
+    }
+}
+
+/*
+ * test_leader_progress_init_multi_node (raft.tla BecomeLeader, Req 3.1)
+ *
+ * Multi-node become-leader path (raft_on_vote_reply → RAFT_BECAME_LEADER).
+ * Non-zero restored log (log_len=7): on reaching quorum, next_index[j] must equal
+ * log_len+1 (=8) and match_index[j] must equal 0 for EVERY peer j in [0, n_peers).
+ */
+static void test_leader_progress_init_multi_node(void)
+{
+    raft_state_t     s;
+    raft_callbacks_t cbs = make_mock_cbs();
+
+    reset_mock();
+    TEST_ASSERT_EQUAL_INT(0, init_node_log_len(&s, &cbs, 3, 0, 7));
+    TEST_ASSERT_EQUAL_UINT64(7, s.log_len);
+
+    /* Drive to CANDIDATE then reach quorum with one peer grant. */
+    TEST_ASSERT_EQUAL_INT(RAFT_OK, raft_start_election(&s));
+    TEST_ASSERT_EQUAL_INT(RAFT_CANDIDATE, s.role);
+
+    int rc = raft_on_vote_reply(&s, 1, 1, s.term);
+    TEST_ASSERT_EQUAL_INT(RAFT_BECAME_LEADER, rc);
+    TEST_ASSERT_EQUAL_INT(RAFT_LEADER, s.role);
+
+    for (int j = 0; j < s.n_peers; j++) {
+        TEST_ASSERT_EQUAL_UINT64(s.log_len + 1, s.next_index[j]);
+        TEST_ASSERT_EQUAL_UINT64(0, s.match_index[j]);
+    }
+}
+
 /* ---------- raft_on_election_timeout tests (task 3.5) ---------- */
 
 /*
@@ -4010,6 +4082,8 @@ void test_raft(void)
     RUN_TEST(test_vote_reply_no_quorum_all_replied_3node);
     RUN_TEST(test_vote_reply_quorum_5node);
     RUN_TEST(test_vote_reply_pending_waiting);
+    RUN_TEST(test_leader_progress_init_single_node);
+    RUN_TEST(test_leader_progress_init_multi_node);
 
     /* raft_on_vote_request (task 3.3) */
     RUN_TEST(test_vote_req_stale_term);