From a6274034921f6af8d5eeba560307653fac1180cb Mon Sep 17 00:00:00 2001
From: Kayos <kayos@sulkta.com>
Date: Thu, 7 May 2026 16:24:34 -0700
Subject: [PATCH] diag: reproducer also reports script bytes-header consistency

---
 .../examples/repro_script_corruption.rs       | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/crates/aldabra-dao/examples/repro_script_corruption.rs b/crates/aldabra-dao/examples/repro_script_corruption.rs
index a0376f1..240f478 100644
--- a/crates/aldabra-dao/examples/repro_script_corruption.rs
+++ b/crates/aldabra-dao/examples/repro_script_corruption.rs
@@ -91,6 +91,48 @@ fn main() {
     if let Some(pos) = find_subseq(&tx_bytes, &script_bytes) {
         println!("✅ FOUND input script bytes verbatim at tx-body offset {}", pos);
         println!("   pallas-txbuilder serialized them clean.");
+
+        // BUT: check the bytes-header that precedes them. In CBOR, a
+        // bytestring of length N has a leader byte of 0x40+N for N<24,
+        // 0x58 + 1 length byte for N<=255, 0x59 + 2 length bytes for
+        // N<=65535. For 7213, header = 0x59 0x1c 0x2d. If the header
+        // claims a different length, encoding is inconsistent.
+        if pos >= 3 {
+            let h = &tx_bytes[pos - 3..pos];
+            println!(
+                "   bytes-header preceding script: {:02x} {:02x} {:02x}",
+                h[0], h[1], h[2]
+            );
+            if h[0] == 0x59 {
+                let claimed_len = u16::from_be_bytes([h[1], h[2]]) as usize;
+                if claimed_len == script_bytes.len() {
+                    println!(
+                        "   ✅ header length {} == input length {} — consistent.",
+                        claimed_len,
+                        script_bytes.len()
+                    );
+                } else {
+                    println!(
+                        "   ❌ header length {} != input length {} — encoder is OFF BY {}.",
+                        claimed_len,
+                        script_bytes.len(),
+                        script_bytes.len() as i64 - claimed_len as i64
+                    );
+                }
+            } else {
+                println!(
+                    "   ⚠️  preceding byte not 0x59 (uint16 bytes header) — different size class?"
+                );
+            }
+        }
+
+        // Print the very first 100 bytes of tx body for inspection
+        let preview_len = 100.min(tx_bytes.len());
+        let preview: String = tx_bytes[..preview_len]
+            .iter()
+            .map(|b| format!("{:02x}", b))
+            .collect();
+        println!("   tx body first {} bytes: {}", preview_len, preview);
     } else {
         println!("❌ DID NOT find input script bytes verbatim in tx body.");
         println!("   pallas-txbuilder mutated the bytes during encoding.");