test(raft-ha-core-safety): machine-checkable walcompare report (task 1.1)

Per-member (lsn,term,pcrc,present) report + committed-vs-uncommitted
divergence classification via walcompare_report()/--report. Soak signal
(OK/exit-code) preserved. 4 new unit tests, all GREEN.

.kiro/specs/raft-ha-core-safety/tasks.md

@@ -7,7 +7,7 @@
 > **Hypothesis discipline:** the term-blind bypass is the primary hypothesis, not proven sole cause. Task 1.3 must reproduce the *live* divergence first; a green synthetic unit test over a still-red soak does not satisfy 1.1/8.1.
 
 - [ ] 1. Foundation: deterministic chaotic harness and live-divergence reproduction
-- [ ] 1.1 Extend the divergence detector to a machine-checkable per-member report
+- [x] 1.1 Extend the divergence detector to a machine-checkable per-member report
   - Extend `walcompare` to emit a parseable per-member `(lsn -> term, payload-crc, present/MISSING)` report over the committed prefix, and classify each divergence as committed vs uncommitted
   - Observable completion: `walcompare` prints a parseable per-member report and a committed-vs-uncommitted classification; the existing soak still detects the round-3 LSN divergence through it
   - _Requirements: 7.1, 7.5_

src/controller/testsuite/test.c

@@ -721,41 +721,54 @@ int cmd_waldump(int argc, char* argv[])
     return rc;
 }
 
-/* walcompare [--committed N] <memberA> <memberB> [more...] — diff member WAL
- * committed prefixes by (lsn -> term, pcrc) and FAIL (nonzero) on any
+/* walcompare [--report] [--committed N] <memberA> <memberB> [more...] — diff
+ * member WAL committed prefixes by (lsn -> term, pcrc) and FAIL (nonzero) on any
  * committed-prefix divergence (ha-term-safety R6.1/R6.2/R6.3), reusing the
  * waldump decoder. Each member path may be a seg-*.wal file, a wal/ dir, or a
  * node/data dir (same resolution as waldump). With no --committed, the shared
  * committed boundary = the minimum CRC-intact tip across members. The diverging
- * LSN and per-member (term, pcrc) identities are reported. Exit 0 = identical,
- * nonzero = divergence or load error — so it doubles as a scripted assertion. */
+ * LSN and per-member (term, pcrc) identities are reported. With --report, also
+ * emit a machine-checkable per-member `(lsn, term, pcrc, status)` table and a
+ * committed-vs-uncommitted classification for each divergence (task 1.1). Exit
+ * 0 = identical, nonzero = divergence or load error — so it doubles as a
+ * scripted assertion. */
 int cmd_walcompare(int argc, char* argv[])
 {
-    uint64_t committed = 0; /* 0 = derive the shared boundary */
+    uint64_t committed = 0;  /* 0 = derive the shared boundary */
+    int      report   = 0;   /* --report => full per-member machine table */
     int      ai        = 1;
 
-    /* Optional global committed boundary applied to every member. */
-    if (argc > ai && strcmp(argv[ai], "--committed") == 0) {
-        if (argc <= ai + 1) {
-            fprintf(stderr, "walcompare: --committed needs an LSN\n");
-            return -1;
+    /* Optional flags (any order): --report, --committed N. */
+    for (;;) {
+        if (argc > ai && strcmp(argv[ai], "--report") == 0) {
+            report = 1;
+            ai += 1;
+            continue;
         }
-        char*         end = NULL;
-        unsigned long v   = strtoul(argv[ai + 1], &end, 10);
-        if (end == argv[ai + 1] || *end != '\0') {
-            fprintf(stderr, "walcompare: bad --committed LSN '%s'\n",
-                    argv[ai + 1]);
-            return -1;
+        if (argc > ai && strcmp(argv[ai], "--committed") == 0) {
+            if (argc <= ai + 1) {
+                fprintf(stderr, "walcompare: --committed needs an LSN\n");
+                return -1;
+            }
+            char*         end = NULL;
+            unsigned long v   = strtoul(argv[ai + 1], &end, 10);
+            if (end == argv[ai + 1] || *end != '\0') {
+                fprintf(stderr, "walcompare: bad --committed LSN '%s'\n",
+                        argv[ai + 1]);
+                return -1;
+            }
+            committed = (uint64_t)v;
+            ai += 2;
+            continue;
         }
-        committed = (uint64_t)v;
-        ai += 2;
+        break;
     }
 
     int n = argc - ai;
     if (n < 2) {
         fprintf(stderr,
-                "usage: walcompare [--committed N] <memberA> <memberB> "
-                "[more...]\n");
+                "usage: walcompare [--report] [--committed N] <memberA> "
+                "<memberB> [more...]\n");
         return -1;
     }
     if (n > 16) {
@@ -770,7 +783,8 @@ int cmd_walcompare(int argc, char* argv[])
     }
 
     walcompare_divergence_t div;
-    int rc = walcompare(members, n, stdout, &div);
+    int rc = report ? walcompare_report(members, n, stdout, &div)
+                    : walcompare(members, n, stdout, &div);
     if (rc == WALCMP_OK)
         return 0;
     if (rc == WALCMP_DIVERGENT) {

src/controller/testsuite/test_walcompare.c

@@ -354,6 +354,160 @@ static void test_too_few_members_errors(void)
     TEST_ASSERT_LESS_THAN_INT(0, rc);
 }
 
+/* ------------------------------------------------------------------ */
+/* Machine-checkable report: a committed-prefix divergence must emit a   */
+/* parseable per-member line set and a committed-vs-uncommitted          */
+/* classification (task 1.1, R7.1/R7.5). Captured via open_memstream so  */
+/* the exact greppable tokens are asserted, not just the verdict.        */
+/* ------------------------------------------------------------------ */
+static void test_machine_report_committed_divergence(void)
+{
+    wal_spec_t a_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+        { 2, WAL_JOB_SUBMIT, "jobB" }, /* LSN 3, term 2 */
+    };
+    wal_spec_t b_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+        { 3, WAL_JOB_SUBMIT, "jobB" }, /* LSN 3, term 3 — divergent */
+    };
+    char a[256], b[256];
+    build_member(a, sizeof(a), a_specs, 3);
+    build_member(b, sizeof(b), b_specs, 3);
+
+    char*  buf = NULL;
+    size_t len = 0;
+    FILE*  out = open_memstream(&buf, &len);
+    TEST_ASSERT_NOT_NULL(out);
+
+    walcompare_member_t m[2] = { { a, 0 }, { b, 0 } };
+    walcompare_divergence_t div;
+    int rc = walcompare(m, 2, out, &div);
+    fclose(out);
+
+    TEST_ASSERT_EQUAL_INT(WALCMP_DIVERGENT, rc);
+    /* committed-vs-uncommitted classification line. */
+    TEST_ASSERT_NOT_NULL(strstr(buf, "WALCMP_DIVERGENCE"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "class=committed"));
+    /* parseable per-member lines with fixed field order. */
+    TEST_ASSERT_NOT_NULL(strstr(buf, "WALCMP member=0 lsn=3"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "WALCMP member=1 lsn=3"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "status=present"));
+    /* divergence struct carries the committed classification flag. */
+    TEST_ASSERT_EQUAL_INT(1, div.committed);
+    free(buf);
+}
+
+/* ------------------------------------------------------------------ */
+/* walcompare_report emits a full per-member, per-committed-LSN table    */
+/* (lsn, term, pcrc, status) for identical members and a clean verdict.  */
+/* ------------------------------------------------------------------ */
+static void test_report_full_member_table(void)
+{
+    wal_spec_t specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+        { 2, WAL_JOB_SUBMIT, "jobB" },
+    };
+    char a[256], b[256], c[256];
+    build_member(a, sizeof(a), specs, 3);
+    build_member(b, sizeof(b), specs, 3);
+    build_member(c, sizeof(c), specs, 3);
+
+    char*  buf = NULL;
+    size_t len = 0;
+    FILE*  out = open_memstream(&buf, &len);
+    TEST_ASSERT_NOT_NULL(out);
+
+    walcompare_member_t m[3] = { { a, 0 }, { b, 0 }, { c, 0 } };
+    walcompare_divergence_t div;
+    int rc = walcompare_report(m, 3, out, &div);
+    fclose(out);
+
+    TEST_ASSERT_EQUAL_INT(WALCMP_OK, rc);
+    /* every member appears at every committed LSN with committed=1. */
+    TEST_ASSERT_NOT_NULL(strstr(buf, "WALCMP member=0 lsn=1"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "WALCMP member=2 lsn=3"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "committed=1"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "status=present"));
+    free(buf);
+}
+
+/* ------------------------------------------------------------------ */
+/* A MISSING committed entry is tagged status=MISSING in the report,     */
+/* and classified class=committed (a committed-prefix hole, R4.2/R6.4).  */
+/* ------------------------------------------------------------------ */
+static void test_report_missing_tagged(void)
+{
+    wal_spec_t a_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+        { 2, WAL_JOB_SUBMIT, "jobB" },
+    };
+    wal_spec_t b_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+    };
+    char a[256], b[256];
+    build_member(a, sizeof(a), a_specs, 3);
+    build_member(b, sizeof(b), b_specs, 2);
+
+    char*  buf = NULL;
+    size_t len = 0;
+    FILE*  out = open_memstream(&buf, &len);
+    TEST_ASSERT_NOT_NULL(out);
+
+    walcompare_member_t m[2] = { { a, 3 }, { b, 3 } };
+    walcompare_divergence_t div;
+    int rc = walcompare_report(m, 2, out, &div);
+    fclose(out);
+
+    TEST_ASSERT_EQUAL_INT(WALCMP_DIVERGENT, rc);
+    TEST_ASSERT_NOT_NULL(strstr(buf, "status=MISSING"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "class=committed"));
+    TEST_ASSERT_EQUAL_INT(1, div.committed);
+    free(buf);
+}
+
+/* ------------------------------------------------------------------ */
+/* A divergence in the UNCOMMITTED tail (above the committed boundary) is */
+/* reported class=uncommitted and is NON-fatal: the committed verdict is  */
+/* still WALCMP_OK (task 1.1 classification; §6.1 committed-prefix only).  */
+/* ------------------------------------------------------------------ */
+static void test_report_uncommitted_tail_classified(void)
+{
+    wal_spec_t a_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" }, /* committed LSN 2 */
+        { 2, WAL_JOB_SUBMIT, "uncA" }, /* LSN 3 uncommitted, divergent */
+    };
+    wal_spec_t b_specs[] = {
+        { 1, WAL_NOOP, NULL },
+        { 1, WAL_JOB_SUBMIT, "jobA" },
+        { 9, WAL_JOB_SUBMIT, "uncB" }, /* LSN 3, different term+bytes */
+    };
+    char a[256], b[256];
+    build_member(a, sizeof(a), a_specs, 3);
+    build_member(b, sizeof(b), b_specs, 3);
+
+    char*  buf = NULL;
+    size_t len = 0;
+    FILE*  out = open_memstream(&buf, &len);
+    TEST_ASSERT_NOT_NULL(out);
+
+    /* committed boundary pinned at 2 → LSN-3 divergence is the tail. */
+    walcompare_member_t m[2] = { { a, 2 }, { b, 2 } };
+    walcompare_divergence_t div;
+    int rc = walcompare_report(m, 2, out, &div);
+    fclose(out);
+
+    TEST_ASSERT_EQUAL_INT(WALCMP_OK, rc); /* tail divergence is non-fatal */
+    TEST_ASSERT_NOT_NULL(strstr(buf, "class=uncommitted"));
+    TEST_ASSERT_NOT_NULL(strstr(buf, "committed=0"));
+    free(buf);
+}
+
 void test_walcompare(void)
 {
     RUN_TEST(test_identical_members_ok);
@@ -367,4 +521,8 @@ void test_walcompare(void)
     RUN_TEST(test_three_members_divergent_config_marker);
     RUN_TEST(test_missing_member_errors);
     RUN_TEST(test_too_few_members_errors);
+    RUN_TEST(test_machine_report_committed_divergence);
+    RUN_TEST(test_report_full_member_table);
+    RUN_TEST(test_report_missing_tagged);
+    RUN_TEST(test_report_uncommitted_tail_classified);
 }

src/controller/testsuite/walcompare.c

@@ -132,79 +132,202 @@ static int load_member(const walcompare_member_t* src, member_log_t* m, FILE* ou
     return 0;
 }
 
-int walcompare(const walcompare_member_t* members, int n, FILE* out,
-               walcompare_divergence_t* div)
-{
-    if (!members || n < 2)
-        return -EINVAL;
-    if (n > WALCMP_MAX_MEMBERS)
-        return -E2BIG;
-
+/* Loaded cluster state shared by walcompare() and walcompare_report(). */
+typedef struct {
     member_log_t logs[WALCMP_MAX_MEMBERS];
-    int          loaded = 0;
-    int          rc     = 0;
+    int          n;
+    int          loaded;   /* members successfully loaded (for cleanup) */
+    uint64_t     boundary; /* highest committed LSN compared (committed edge) */
+    uint64_t     max_tip;  /* highest recovered tip across members (tail edge) */
+} wc_cluster_t;
+
+/* Stable status token for one member at one LSN. */
+static const char* wc_status(const member_log_t* m, uint64_t lsn)
+{
+    if ((lsn < m->cap) && m->present[lsn])
+        return "present";
+    if (lsn <= m->committed_lsn)
+        return "MISSING"; /* a committed entry this member SHOULD hold (R4.2) */
+    return "beyond";      /* legitimately not held (above its committed prefix) */
+}
+
+/* Load all members and compute the committed boundary + tail edge. On a load
+ * error, frees what loaded, reports to `out`, returns a negative errno. */
+static int wc_load(const walcompare_member_t* members, int n, FILE* out,
+                   wc_cluster_t* cl)
+{
+    memset(cl, 0, sizeof(*cl));
+    cl->n = n;
 
     for (int i = 0; i < n; i++) {
-        rc = load_member(&members[i], &logs[i], out);
+        int rc = load_member(&members[i], &cl->logs[i], out);
         if (rc != 0) {
             if (out)
                 fprintf(out, "walcompare: cannot load member %d ('%s'): %s\n", i,
                         members[i].path ? members[i].path : "(null)",
                         strerror(-rc));
-            goto done;
+            for (int j = 0; j < cl->loaded; j++)
+                member_log_free(&cl->logs[j]);
+            return rc;
         }
-        loaded = i + 1;
+        cl->loaded = i + 1;
     }
 
     /* Shared committed boundary = the minimum recovered tip across members:
      * the largest committed prefix every member can be expected to hold. A
      * member with an explicit committed_lsn keeps its own. */
-    uint64_t shared = logs[0].recovered_tip;
+    uint64_t shared = cl->logs[0].recovered_tip;
     for (int i = 1; i < n; i++)
-        if (logs[i].recovered_tip < shared)
-            shared = logs[i].recovered_tip;
+        if (cl->logs[i].recovered_tip < shared)
+            shared = cl->logs[i].recovered_tip;
 
-    uint64_t boundary = 0; /* highest committed LSN compared across the cluster */
     for (int i = 0; i < n; i++) {
-        if (logs[i].committed_lsn == 0)
-            logs[i].committed_lsn = shared;
-        if (logs[i].committed_lsn > boundary)
-            boundary = logs[i].committed_lsn;
+        if (cl->logs[i].committed_lsn == 0)
+            cl->logs[i].committed_lsn = shared;
+        if (cl->logs[i].committed_lsn > cl->boundary)
+            cl->boundary = cl->logs[i].committed_lsn;
+        if (cl->logs[i].recovered_tip > cl->max_tip)
+            cl->max_tip = cl->logs[i].recovered_tip;
+    }
+    return 0;
+}
+
+static void wc_unload(wc_cluster_t* cl)
+{
+    for (int i = 0; i < cl->loaded; i++)
+        member_log_free(&cl->logs[i]);
+}
+
+/* One machine line for member `i` at `lsn`. Fixed field order, stable tokens. */
+static void wc_emit_member(const wc_cluster_t* cl, int i, uint64_t lsn,
+                           int committed, FILE* out)
+{
+    const member_log_t* m     = &cl->logs[i];
+    int                 holds = (lsn < m->cap) && m->present[lsn];
+    fprintf(out,
+            "WALCMP member=%d lsn=%" PRIu64 " term=%" PRIu64
+            " pcrc=%08x status=%s committed=%d\n",
+            i, lsn, holds ? match_term(m->term[lsn]) : 0,
+            holds ? m->pcrc[lsn] : 0u, wc_status(m, lsn), committed);
+}
+
+/* Full per-member machine table over [1..max_tip]; committed=1 within the
+ * committed boundary, 0 in the uncommitted tail. */
+static void wc_emit_table(const wc_cluster_t* cl, FILE* out)
+{
+    for (uint64_t lsn = 1; lsn <= cl->max_tip; lsn++) {
+        int committed = (lsn <= cl->boundary) ? 1 : 0;
+        for (int i = 0; i < cl->n; i++)
+            wc_emit_member(cl, i, lsn, committed, out);
+    }
+}
+
+/* Emit the classification + per-member identity for ONE diverging LSN. */
+static void wc_emit_divergence(const wc_cluster_t* cl, uint64_t lsn,
+                               int committed, int compared, int present,
+                               FILE* out)
+{
+    fprintf(out,
+            "WALCMP_DIVERGENCE lsn=%" PRIu64 " class=%s compared=%d present=%d\n",
+            lsn, committed ? "committed" : "uncommitted", compared, present);
+    for (int i = 0; i < cl->n; i++)
+        wc_emit_member(cl, i, lsn, committed, out);
+}
+
+/* Compare one committed LSN. Fills `div` (committed=1) and prints the human +
+ * machine report when divergent. Returns 1 if divergent, else 0. */
+static int wc_compare_committed(const wc_cluster_t* cl,
+                                const walcompare_member_t* members, uint64_t lsn,
+                                FILE* out, walcompare_divergence_t* div)
+{
+    int      have = 0, present = 0, have_ref = 0, divergent = 0;
+    uint64_t ref_term = 0;
+    uint32_t ref_pcrc = 0;
+
+    for (int i = 0; i < cl->n; i++) {
+        if (lsn > cl->logs[i].committed_lsn)
+            continue; /* beyond member i's committed prefix */
+        have++;
+        const member_log_t* m     = &cl->logs[i];
+        int                 holds = (lsn < m->cap) && m->present[lsn];
+        if (!holds) {
+            divergent = 1; /* member should hold this committed LSN but doesn't */
+            continue;
+        }
+        present++;
+        uint64_t mt = match_term(m->term[lsn]);
+        uint32_t mp = m->pcrc[lsn];
+        if (!have_ref) {
+            ref_term = mt;
+            ref_pcrc = mp;
+            have_ref = 1;
+        } else if (mt != ref_term || mp != ref_pcrc) {
+            divergent = 1;
+        }
     }
 
-    if (out)
+    if (have < 2 || !divergent)
+        return 0;
+
+    if (div) {
+        memset(div, 0, sizeof(*div));
+        div->lsn       = lsn;
+        div->n_members = cl->n;
+        div->committed = 1;
+        for (int i = 0; i < cl->n && i < 16; i++) {
+            const member_log_t* m = &cl->logs[i];
+            int holds = (lsn <= m->committed_lsn) && (lsn < m->cap) &&
+                        m->present[lsn];
+            div->member_present[i] = holds ? 1 : 0;
+            div->member_term[i]    = holds ? match_term(m->term[lsn]) : 0;
+            div->member_pcrc[i]    = holds ? m->pcrc[lsn] : 0;
+        }
+    }
+    if (out) {
         fprintf(out,
-                "== walcompare: %d members, committed boundary up to LSN %" PRIu64
-                " ==\n",
-                n, boundary);
-
-    /* Walk every committed LSN. At each LSN, compare the (term, pcrc) of the
-     * members whose own committed boundary covers it and that hold the entry.
-     * A member that does not hold a committed LSN it SHOULD (boundary covers it
-     * but the entry is absent) is itself a committed-prefix divergence: a
-     * committed entry is missing (R4.2 / R6.4). */
-    for (uint64_t lsn = 1; lsn <= boundary; lsn++) {
-        int      have       = 0; /* members whose boundary covers this LSN */
-        int      present    = 0; /* of those, how many actually hold it */
-        uint64_t ref_term   = 0;
-        uint32_t ref_pcrc   = 0;
-        int      have_ref   = 0;
-        int      divergent  = 0;
-
-        for (int i = 0; i < n; i++) {
-            if (lsn > logs[i].committed_lsn)
-                continue; /* this LSN is beyond member i's committed prefix */
-            have++;
-
-            int holds = (lsn < logs[i].cap) && logs[i].present[lsn];
-            if (!holds) {
-                /* member i should hold this committed LSN but does not */
-                divergent = 1;
+                "*** DIVERGENCE at committed LSN %" PRIu64
+                " (compared %d, present %d) ***\n",
+                lsn, have, present);
+        for (int i = 0; i < cl->n; i++) {
+            if (lsn > cl->logs[i].committed_lsn) {
+                fprintf(out,
+                        "  member %d ('%s'): LSN beyond its committed prefix"
+                        " (committed=%" PRIu64 ")\n",
+                        i, members[i].path, cl->logs[i].committed_lsn);
                 continue;
             }
+            int holds = (lsn < cl->logs[i].cap) && cl->logs[i].present[lsn];
+            if (holds)
+                fprintf(out, "  member %d ('%s'): term=%" PRIu64 " pcrc=%08x\n",
+                        i, members[i].path, match_term(cl->logs[i].term[lsn]),
+                        cl->logs[i].pcrc[lsn]);
+            else
+                fprintf(out, "  member %d ('%s'): MISSING committed entry\n", i,
+                        members[i].path);
+        }
+        wc_emit_divergence(cl, lsn, 1, have, present, out);
+    }
+    return 1;
+}
+
+/* Scan the uncommitted tail (boundary < lsn <= max_tip): emit a NON-fatal
+ * class=uncommitted classification for any LSN where >=2 members hold the entry
+ * but disagree on (term, pcrc). Never changes the verdict. */
+static void wc_scan_uncommitted(const wc_cluster_t* cl, FILE* out)
+{
+    for (uint64_t lsn = cl->boundary + 1; lsn <= cl->max_tip; lsn++) {
+        int      present = 0, have_ref = 0, divergent = 0;
+        uint64_t ref_term = 0;
+        uint32_t ref_pcrc = 0;
+
+        for (int i = 0; i < cl->n; i++) {
+            const member_log_t* m     = &cl->logs[i];
+            int                 holds = (lsn < m->cap) && m->present[lsn];
+            if (!holds)
+                continue;
             present++;
-            uint64_t mt = match_term(logs[i].term[lsn]);
-            uint32_t mp = logs[i].pcrc[lsn];
+            uint64_t mt = match_term(m->term[lsn]);
+            uint32_t mp = m->pcrc[lsn];
             if (!have_ref) {
                 ref_term = mt;
                 ref_pcrc = mp;
@@ -213,60 +336,69 @@ int walcompare(const walcompare_member_t* members, int n, FILE* out,
                 divergent = 1;
             }
         }
-
-        if (have < 2)
-            continue; /* nothing to compare at this LSN */
-        if (!divergent)
+        if (present < 2 || !divergent)
             continue;
-
-        /* First divergent committed LSN — report and fail. */
-        if (div) {
-            memset(div, 0, sizeof(*div));
-            div->lsn       = lsn;
-            div->n_members = n;
-            for (int i = 0; i < n && i < 16; i++) {
-                int holds = (lsn <= logs[i].committed_lsn) &&
-                            (lsn < logs[i].cap) && logs[i].present[lsn];
-                div->member_present[i] = holds ? 1 : 0;
-                div->member_term[i] = holds ? match_term(logs[i].term[lsn]) : 0;
-                div->member_pcrc[i] = holds ? logs[i].pcrc[lsn] : 0;
-            }
-        }
-        if (out) {
-            fprintf(out,
-                    "*** DIVERGENCE at committed LSN %" PRIu64
-                    " (compared %d, present %d) ***\n",
-                    lsn, have, present);
-            for (int i = 0; i < n; i++) {
-                if (lsn > logs[i].committed_lsn) {
-                    fprintf(out,
-                            "  member %d ('%s'): LSN beyond its committed prefix"
-                            " (committed=%" PRIu64 ")\n",
-                            i, members[i].path, logs[i].committed_lsn);
-                    continue;
-                }
-                int holds = (lsn < logs[i].cap) && logs[i].present[lsn];
-                if (holds)
-                    fprintf(out,
-                            "  member %d ('%s'): term=%" PRIu64 " pcrc=%08x\n", i,
-                            members[i].path, match_term(logs[i].term[lsn]),
-                            logs[i].pcrc[lsn]);
-                else
-                    fprintf(out,
-                            "  member %d ('%s'): MISSING committed entry\n", i,
-                            members[i].path);
-            }
-        }
-        rc = WALCMP_DIVERGENT;
-        goto done;
+        wc_emit_divergence(cl, lsn, 0, present, present, out);
     }
+}
+
+/* Shared driver for walcompare() (full_report=0) and walcompare_report()
+ * (full_report=1). */
+static int wc_run(const walcompare_member_t* members, int n, FILE* out,
+                  walcompare_divergence_t* div, int full_report)
+{
+    if (!members || n < 2)
+        return -EINVAL;
+    if (n > WALCMP_MAX_MEMBERS)
+        return -E2BIG;
+
+    wc_cluster_t cl;
+    int          rc = wc_load(members, n, out, &cl);
+    if (rc != 0)
+        return rc;
+
+    if (out)
+        fprintf(out,
+                "== walcompare: %d members, committed boundary up to LSN %" PRIu64
+                " ==\n",
+                n, cl.boundary);
+
+    if (full_report && out)
+        wc_emit_table(&cl, out);
+
+    /* Walk every committed LSN. At each LSN, compare the (term, pcrc) of the
+     * members whose own committed boundary covers it and that hold the entry.
+     * A member that does not hold a committed LSN it SHOULD is a committed-
+     * prefix divergence: a committed entry is missing (R4.2 / R6.4). */
+    rc = WALCMP_OK;
+    for (uint64_t lsn = 1; lsn <= cl.boundary; lsn++) {
+        if (wc_compare_committed(&cl, members, lsn, out, div)) {
+            rc = WALCMP_DIVERGENT; /* first committed divergence is the verdict */
+            goto done;
+        }
+    }
+
+    /* The committed prefix is identical. In full-report mode also classify any
+     * uncommitted-tail divergence (informational, never fatal). */
+    if (full_report && out)
+        wc_scan_uncommitted(&cl, out);
 
     if (out)
         fprintf(out, "walcompare: OK — committed prefixes identical\n");
-    rc = WALCMP_OK;
 
 done:
-    for (int i = 0; i < loaded; i++)
-        member_log_free(&logs[i]);
+    wc_unload(&cl);
     return rc;
 }
+
+int walcompare(const walcompare_member_t* members, int n, FILE* out,
+               walcompare_divergence_t* div)
+{
+    return wc_run(members, n, out, div, 0);
+}
+
+int walcompare_report(const walcompare_member_t* members, int n, FILE* out,
+                      walcompare_divergence_t* div)
+{
+    return wc_run(members, n, out, div, 1);
+}

src/controller/testsuite/walcompare.h

@@ -32,6 +32,9 @@ typedef struct {
     uint64_t member_term[16];     /* per-member matched term at lsn */
     uint32_t member_pcrc[16];     /* per-member payload CRC at lsn */
     int      member_present[16];  /* 1 if the member holds this LSN, else 0 */
+    int      committed;           /* 1 = divergence within the committed prefix
+                                   * (lsn <= committed boundary, a safety
+                                   * violation); 0 = uncommitted tail divergence */
 } walcompare_divergence_t;
 
 /* Result codes. */
@@ -62,3 +65,29 @@ enum {
  */
 int walcompare(const walcompare_member_t* members, int n, FILE* out,
                walcompare_divergence_t* div);
+
+/* Same comparison as walcompare(), but ALSO emits a machine-checkable,
+ * per-member report over the full log: one
+ *
+ *   WALCMP member=<i> lsn=<L> term=<T> pcrc=<8hex> status=<present|MISSING|beyond> committed=<0|1>
+ *
+ * line per (member, LSN) for every LSN in [1..max-recovered-tip], where
+ * `committed=1` iff the LSN is within the committed boundary. Each divergence
+ * additionally emits a
+ *
+ *   WALCMP_DIVERGENCE lsn=<L> class=<committed|uncommitted> compared=<c> present=<p>
+ *
+ * classification line. A `committed` divergence is fatal (verdict
+ * WALCMP_DIVERGENT, `div->committed = 1`); an `uncommitted`-tail divergence
+ * (above the committed boundary) is reported but NON-fatal — the verdict stays
+ * WALCMP_OK when the committed prefix is identical. Field order is fixed and
+ * the tokens are stable so the harness can grep them. `out` must be non-NULL.
+ *
+ * Backward-compatible: walcompare() keeps its original concise output (the
+ * `== walcompare ==` header, the human divergence block, and the final
+ * `walcompare: OK` verdict line) and additionally emits the machine
+ * classification at a committed divergence; only walcompare_report() prints the
+ * full per-LSN table and scans the uncommitted tail.
+ */
+int walcompare_report(const walcompare_member_t* members, int n, FILE* out,
+                      walcompare_divergence_t* div);