v4.2.1: info correctly reports --pq-only vs hybrid post-quantum mode

`vaptvupt info` mislabelled full post-quantum (--pq-only, enc_type 0x06)
archives as "PQ Hybrid: YES (ML-KEM-768 + X25519)". Full-PQ archives set
the generic ZUPT_FLAG_PQ_HYBRID header flag (the enc_type byte is what
distinguishes hybrid 0x02 from pure 0x06), but info only checked the flag.

info now seeks to hdr.encryption_header_off, reads the real enc_type from
the encryption-header block, and reports the actual mode: "ML-KEM-768
only, no classical layer" for --pq-only, and hybrid / SDK-v2 / sealed-box
for the others. Reader-side only — no wire-format change; existing 4.2.0
archives are relabelled correctly with no re-encryption.

CHANGELOG.md

@@ -1,6 +1,22 @@
 # VaptVupt Changelog
 
 
+## [4.2.1] — 2026-07-10 — `info` correctly reports the post-quantum mode
+
+### Fixed
+
+- **`vaptvupt info` mislabelled `--pq-only` archives as hybrid.** Full
+  post-quantum archives set the generic `ZUPT_FLAG_PQ_HYBRID` header flag (the
+  `enc_type` byte is what distinguishes hybrid `0x02` from pure `0x06`), but
+  `info` only checked the flag and always printed "PQ Hybrid: YES (ML-KEM-768 +
+  X25519)". It now reads the real `enc_type` from the encryption-header block
+  and reports the actual mode: "ML-KEM-768 only, no classical layer" for
+  `--pq-only`, and hybrid / SDK-v2 / sealed-box for the others. Reader-side only
+  — no wire-format change; existing 4.2.0 archives are relabelled correctly with
+  no re-encryption. The crypto was always correct; only the `info` label was
+  wrong.
+
+
 ## [4.2.0] — 2026-07-09 — Full (pure) post-quantum mode; dedup keystream-reuse fix
 
 ### Added — full post-quantum encryption (`--pq-only`)

doc/vaptvupt.1

@@ -1,7 +1,7 @@
 .\" Manpage for vaptvupt (formerly zupt; INPI Brasil trademark rename in v3.0.0)
 .\" SPDX-License-Identifier: AGPL-3.0-or-later
 .\" Copyright (c) 2025-2026 Cristian Cezar Moisés
-.TH VAPTVUPT 1 "July 2026" "vaptvupt 4.2.0" "User Commands"
+.TH VAPTVUPT 1 "July 2026" "vaptvupt 4.2.1" "User Commands"
 
 .SH NAME
 vaptvupt \- post-quantum backup compression utility (formerly zupt)

include/zupt.h

@@ -50,7 +50,7 @@
 #define ZUPT_PRODUCT_EXTENSION ".zupt"           /* on-disk archive extension (kept stable) */
 #define ZUPT_PRODUCT_TAGLINE   "Post-quantum backup compression"
 
-#define ZUPT_VERSION_STRING "4.2.0"
+#define ZUPT_VERSION_STRING "4.2.1"
 /* Vendored codec release (upstream tag) — single source for display strings.
  * The codec's own VV_VERSION_* is its internal API version, not the release. */
 #define ZUPT_CODEC_RELEASE "2.60.4"

src/zupt_format.c

@@ -2903,6 +2903,23 @@ zupt_error_t zupt_archive_info(const char *path) {
             has_footer = 1;
         }
     }
+
+    /* Read the real enc_type from the encryption-header block so `info` can
+     * distinguish hybrid --pq (0x02) from full --pq-only (0x06), the SDK-v2
+     * (0x03) and sealed-box (0x05) modes — the ZUPT_FLAG_PQ_HYBRID header flag
+     * is a generic PQ indicator set by all of them. Block layout from
+     * write_enc_header: 7-byte prefix (magic0,magic1,block_type,codec u16,
+     * flags u16) + varint(len) + varint(len) + u64 xxh64 + enc_hdr[0]=enc_type. */
+    uint8_t enc_type = 0;
+    if ((hdr.global_flags & ZUPT_FLAG_ENCRYPTED) && hdr.encryption_header_off != 0 &&
+        fseeko(f, (off_t)hdr.encryption_header_off + 7, SEEK_SET) == 0) {
+        uint64_t l1 = 0, l2 = 0;
+        if (zupt_read_varint(f, &l1) > 0 && zupt_read_varint(f, &l2) > 0 &&
+            fseeko(f, 8, SEEK_CUR) == 0) {
+            uint8_t b;
+            if (fread(&b, 1, 1, f) == 1) enc_type = b;
+        }
+    }
     fclose(f);
 
     /* UUID */
@@ -2938,8 +2955,23 @@ zupt_error_t zupt_archive_info(const char *path) {
     if (has_footer)
         printf("  Blocks:        %llu\n", (unsigned long long)total_blocks);
     printf("  Encrypted:     %s\n", (fl & ZUPT_FLAG_ENCRYPTED) ? "YES" : "no");
-    if (fl & ZUPT_FLAG_PQ_HYBRID)
+    if (fl & ZUPT_FLAG_PQ_HYBRID) {
-        printf("  PQ Hybrid:     YES (ML-KEM-768 + X25519)\n");
+        switch (enc_type) {
+            case ZUPT_ENC_PQ_ONLY:
+                printf("  Post-quantum:  YES (ML-KEM-768 only, no classical layer)\n");
+                break;
+            case ZUPT_ENC_PQ_SDK_V2:
+                printf("  Post-quantum:  YES (ML-KEM-768 + X25519, SDK v2 + HPKE)\n");
+                break;
+            case ZUPT_ENC_PQ_BOX_V1:
+                printf("  Post-quantum:  YES (ML-KEM-768 + X25519, sealed box)\n");
+                break;
+            case ZUPT_ENC_PQ_HYBRID:
+            default:
+                printf("  Post-quantum:  YES (ML-KEM-768 + X25519, hybrid)\n");
+                break;
+        }
+    }
     if (fl & ZUPT_FLAG_SOLID)
         printf("  Solid:         YES\n");
     if (fl & ZUPT_FLAG_MULTITHREADED)