Fix Terminal Fork edge-case

off-chain/lib/trie.js

@@ -342,7 +342,7 @@ export class Trie {
   async get(key) {
     // Convert the key into a path of nibbles
     const path = intoPath(key);
-
+    
     // Use childAt to find the node corresponding to the path
     const node = await this.childAt(path);
 
@@ -1369,8 +1369,26 @@ export class Proof {
 
         case Proof.#TYPE_FORK: {
           if (!includingItem && isLastStep) {
-            const prefix = [Buffer.from([step.neighbor.nibble]), step.neighbor.prefix];
-            return digest(Buffer.concat([...prefix, step.neighbor.root]));
+            if (step.skip === 0) {
+              // Original logic that works for skip = 0
+              const prefix = [
+                Buffer.from([step.neighbor.nibble]),
+                step.neighbor.prefix,
+              ];
+              return digest(Buffer.concat([...prefix, step.neighbor.root])); // nibble + prefix + root
+            } else {
+              // For skip > 0, we need to reconstruct the original neighbor node
+              // before the fork was created. The original node had the full prefix:
+              // (common prefix from skip) + (neighbor nibble) + (neighbor's current prefix)
+              // Match onchain: bytearray.concat(nibbles(path, cursor, cursor + skip), bytearray.push(neighbor.prefix, neighbor.nibble))
+              const skippedPath = nibbles(this.#path.slice(cursor, cursor + step.skip));
+              const nibblePlusPrefix = Buffer.concat([
+                Buffer.from([step.neighbor.nibble]),
+                step.neighbor.prefix,
+              ]);
+              const originalPrefix = Buffer.concat([skippedPath, nibblePlusPrefix]);
+              return digest(Buffer.concat([originalPrefix, step.neighbor.root]));
+            }
           }
 
           assert(step.neighbor.nibble !== thisNibble);

on-chain/lib/aiken/merkle-patricia-forestry.ak

@@ -308,10 +308,23 @@ fn do_excluding(path: ByteArray, cursor: Int, proof: Proof) -> ByteArray {
       do_branch(path, cursor, nextCursor, root, neighbors)
     }
 
-    [Fork { neighbor, .. }] -> {
-      let prefix = bytearray.push(neighbor.prefix, neighbor.nibble)
-      combine(prefix, neighbor.root)
-    }
+    [Fork { skip, neighbor }] ->
+      if skip == 0 {
+        // Original logic that works for skip = 0
+        let prefix = bytearray.push(neighbor.prefix, neighbor.nibble)
+        combine(prefix, neighbor.root)
+      } else {
+        // nibble + prefix + root 
+        // For skip > 0, we need to reconstruct the original neighbor node
+        // before the fork was created. The original node had the full prefix:
+        // (common prefix from skip) + (neighbor nibble) + (neighbor's current prefix)
+        let originalPrefix =
+          bytearray.concat(
+            nibbles(path, cursor, cursor + skip),
+            bytearray.push(neighbor.prefix, neighbor.nibble),
+          )
+        combine(originalPrefix, neighbor.root)
+      }
 
     [Fork { skip, neighbor }, ..steps] -> {
       let nextCursor = cursor + 1 + skip

on-chain/lib/aiken/merkle-patricia-forestry.tests.ak

@@ -9,6 +9,332 @@ use aiken/merkle_patricia_forestry.{
 // --------------------------------------------------------------------- bitcoin
 // -----------------------------------------------------------------------------
 
+const edge_case_proof8: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"dd79d1a4980ff4ab374d6ed011b6a9b963fe5fd141a669fb20ef0f08250c9d928bdce2239643c187358c1abf47ae78136d7d8dce94b9c2bd22f4f3b1427c90b4aed17c11bddfc6d68b809b2de8f5129c43804516b4e6d67625c5780032dc0dad97b4d37f1699995fb7572eef017468819b948c8a16ec9732479d1d70c80996cd",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"63e2bed77aaf8034c17f5becd9d9e92c1820bd0609a0c92cf5746249270ad35ee6f92b945bbfa738a4d97409aaca86d9d44671b3da48a36dfb464501d9d147e4bffffd78b82dcef21e5d140e97318b8dfd1808014f2a02cf6057f460b203968e48554ea8b75d879edd62b154628ae8c30600b9e50434f0695ba6dd67465c8153",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"054c6807d1047ebe0b79cd7fec4b341037400ef79a30e50a81062f4a7b8df0ef7c423847528893fe54621016e0df78000987b3d47f0b43769035d3ca844ab93893146efd718347306d9c6699a27db53997c1a06d89ad7fc741a615cf6848c1eb2e83ea7273c04abfabca2cce83614304df0c68d0189764d9f6ba29e9091404f9",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 12,
+        prefix: #"",
+        root: #"cbf9b55ffdf4dbc9964cb51a01e6d66fae05bfb1704c057b8b0affb9eb8f6d3b",
+      },
+    },
+  ]
+
+test insert_edge_case8() {
+  let trie =
+    mpf.from_root(
+      #"d80496796601a1cdbad2912ba69af57185738594da390f36b65e237906808a89",
+    )
+  let block_hash =
+    #"541dddfaf11096844f045f162c0d3095597a16f711432a91e36cff007665efdc"
+  let block_body = #"272f42edb4c1c334cb38ebbe0772dc3c10"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof8) == mpf.from_root(
+    #"6308f158d046f2d7928fcae02b66e12831dc42f33e5d89591ae9fa7f92726e42",
+  )
+}
+
+const edge_case_proof7: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"7391436705a8141e333c007c5ea3e046f9b6ce3200988f4323b337f1eb4e476e300fc77899d6c430dc56965b5171ed48ae947e00cf886ed36bd508f01ecdcfd0a61383bae3451edfa124b8b4a0d6a36f9634c9dcdb9684492bc1f1962a38247ba4ea8e58b84473436d6b6fc5fd47a3abef4959544f8e57bc62ba48131198e476",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"a8c0876243c8203192c45e572b91b84654915f3015e99fbf2a50d2d48bbdacf73a1077fa66a5e7159d0971ce3192d128158480293bd98923ea6614f444c91684b55f810f03a8a710183c7ffff4272817d630c6ffae2600accdedc9f656fa9283571838701edb01d0ec362c174d12243a426af448fb909d32ed51d8641c3a43b0",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"72302f4a439c2294ba4f6bef321f0f7bf497bb5c24335f2e1c8d0b49237410297674c4a5f9437696d4ed2145aad20cc0ef39bc139574941c9f24a4023706e7720d1a0c3d36e6748cabab8c24cb83a17b4a771f536a9fd361e1416f673ed43708b61ff685cecf3bd4a6118e3994e36e41e8dcaee8b47b2ea947968c0afca65b6e",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"f226865e02694067e1d0a17b3cb0f6c3d7e5186642a3ff1d8299573e3cac04673fced676fe9af960d3ed3d1e6138952993109b7ec62a3f38eae39fb89a06f04436b86983490a9c2488d8b690074fb3b6a487049f21b6de07dd27b8cfb6243fc3ab5d438a30e24aee9016ffb83a2c23ed7f316efac775c6c2eec64f41967e63c2",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 11,
+        prefix: #"0e",
+        root: #"8ffc29f174b749ee61bc9048cb600b4b7b9379227cf690a9268ffa26c5973738",
+      },
+    },
+  ]
+
+test insert_edge_case7() {
+  let trie =
+    mpf.from_root(
+      #"5032a544857633269c915dd4fb665d79a041d6d75ca795e24fc17a285cc1dece",
+    )
+  let block_hash =
+    #"daa708d4b3fcf81fdfb8fce2ec5ff61fa38ff02fb4f4d9a218c158b2de170b20"
+  let block_body = #"9fb48cf6f576d74b1d7d8917"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof7) == mpf.from_root(
+    #"b4b1446e07f17da9643a597e5b3a805bc75307aec8a40edde1e41b22ffb90442",
+  )
+}
+
+const edge_case_proof6: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"7e5c1b89d6ba9e8e5a012933aecd9e2e19f11294257e0e640e56c6845219261a4b1698ae92f74ac507f5680ca387481abd062fa046eb010b7b418153b9988fcf5bb476f0fc4b22846acdcf91c26b8405a09e21af7441dfe98e144b7e6f7475ce14a7917333baaf877fa3e6562e09e9e5539bb5731c89006ba3baf3317ea7cfd3",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"4945551523513a913b0c1748f0087865b5ef401247edca73d8ce823cedc62003ed7b7f4cfcedd277e93783a47475a8ec717761fbb2274bc09e00ea1a5fbcecb4b524a3388171fafdd68d4422401a634bbd85b7bab7260585112368ccb4dfcdc8470742a8dd6e058a84e82d5842ebfad6af4a0add6f167106e3c8bf8274e3f346",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"ccd2c106aeec88ac21a434fde3a80f6723bdaec66dbbf7b48798444176a66b313666175fd5c77515a487b92353e8b38975faa4fe8c781d20dbcf8e047dd4fb65ef96a189a702eba153af570fcd3fe5fcc246291520c8be76a28a513e0af3df2c1c0a21c307b69cc6de481a61fb485d0b6749347e2536c50f55ce95f4c8aeb9df",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"e6100e9747bf02da887ba2f15c77d151a6dafe424bfc2e4a575ce3be326d98938e810047967285276146d6cec58822f67af42393612eb7bf7f3419f20f7ddaab74699bfa72ad77a7e24e80960c3913a02dbc1300aedf4efef7448a1817eaaac0739f0ca36791ab54cb58545461e737e19eda3fddcbb16f771b28987206f90778",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"13e7ec23fb284cde60f0c5434f220256c0fcab29390bbb44be517239f63739e093b12de2213d6991bfed2f7a7a9204382975b655347e1b3c22fb35791a3ab6f60eb923b0cbd24df54401d998531feead35a47a99f4deed205de4af81120f9761807800df400ecd72d0f96b90289c6c9e30745c0f0f1b87dda505807bf113cd18",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 9,
+        prefix: #"0c",
+        root: #"03be633c718bddfa31a6cc2988f933a12fe3d630ce46981090a673023c550a75",
+      },
+    },
+  ]
+
+test insert_edge_case6() {
+  let trie =
+    mpf.from_root(
+      #"264bf8da18ca79f8da1b3907d7587a5933599c113e9fb6a43e4659dcaa7dfb14",
+    )
+  let block_hash =
+    #"5247268e194dad520a2ab88837e2c110fbe290fa3ee8e09b8fe10402b7f9e906"
+  let block_body =
+    #"4852f1a645b5c206f9b97f679af0e1629954f73d43080a5ebb9bf54f12131b"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof6) == mpf.from_root(
+    #"b59233f804a519ea064071251d1f948cd129543c2ece3932f001a593c99409dc",
+  )
+}
+
+const edge_case_proof5: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"83a353b3dfac1b00ec6333120a92996ce6e715029a72c9f224731b83d2d0da467dab0e24c4582fde651ef4f6fc292de9f674587c72439c2ebe10c5d8e0dd993cdb010bae8afbb2ef4563525f7f6df6250069efc4c6a7cfed090aa4de8a0b0943a9d4662d42439fdc9b0886bac8437ac6f870eb740c0aaac8900f0f07f6ca627c",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"fd83b02dec57c8d7c9c5709d216d7ece94aede0be367de0fba419efe0ea14fb5c183494e24e67b0ada22146e6c274ef2e615e31ef16a8d8e87001a3564597430615bb2668745780b8800fc1267f73736d76e804c292baf556edb21f6554b5277d6887507e528c0a75cbd0663e89ce6c1d58d425a5892588a1ad7d722c150ad35",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"fc880494853e132b1e5059ef097ac8052406e91c497a4b3220d461aebe24bc8011cb48bbb1fc48f83dcbdabacbadd5252b5a4aa9ce0cb11e469a487e5185e29a889fea6ad82b59c6b6545f1eb07ec79cef0b49996a0ed1f93b4d7e0fd19120bbced4fd32785b26b24acc48b334dc9cbb57d131811b209bd34e1c2eabdddd824b",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"2ac6a5bf86058b926969d57744a861c1ed0354e4a8597b30286da55ad65bc70888f678a79d87971609b0ebcb59957b2fb7a49b974988b622b609a172a22b07113c8d0c0385974874a96f9d2a8bf40b887f1a2770e10e2ad932452625dd092e32eeb0ecc037555a8be1b495c51f193e9e4a2b0394d508d985c368f76f41845c30",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"55b2b16593856d4f82e890477c446e0f6701065c0f8211d209e2c51ea140b4ef975439d6994d2a1320b64cd109fe3ba5f2e3cc6a1d901e18d4146c058294a0fd5199a4a23258ebe527b0f845549ae5b7c6abfb6a3ce51065788b24e0d3b6df590000000000000000000000000000000000000000000000000000000000000000",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 2,
+        prefix: #"06",
+        root: #"afa03b4357df9c84cadd1dc8c488d01718a35f4dd467f4a9be010f09f1cfa5bc",
+      },
+    },
+  ]
+
+test insert_edge_case5() {
+  let trie =
+    mpf.from_root(
+      #"7dc784628201add8ee3e19eef299af13d8be6b46189b5bfd95c8ab331e97bb00",
+    )
+  let block_hash =
+    #"e4a80cba017707ab102628bb4edd6f463ad3f5592c537c69b5d7f4f6dbae5c63"
+  let block_body = #"61255c62f82fa03634e7f2be38b0589ed878c7293e41"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof5) == mpf.from_root(
+    #"5c788efef5680d2ce466fa44943999262f5215d29263cf46069eb9a49728125f",
+  )
+}
+
+const edge_case_proof4: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"d072e11c4f761d09ebe0c1df54b08d398977aa4e98e85e5e231f52dc32fdf8053861a5ea164ac3eb460e27f96ba934832bfc7b240dbf7be24d3fb7ae16f3e44fa965498aa2e219f45428bafc4f646a8f2b4d863bf730f802f81f4f713a465246cd28ad53627981fd212ebec41068fa0f4b0ae5e0e77af0143e296373c6c8f753",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"6c2cf6703c1b121726899e4f1de29cf483227d9e75d5d7948b62b5904c7f1011165b8313abcd4f1c33b85a5dabf8c5096039b3aba1c1fedda2e247810090173998f6f58a03bc17874bff8ba7eda08d25623911dff348f57da60b8545044dcbb175d27abc4c3e1b9aa0a3161ea0f8067ef39885c30399c164395b181747ba4f51",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"c5b1eb4266a20e13961f0b7b8f909a217141eecab5bbe3116665e382f87477fcf9a8a6a9e1e1cb7af32d1ffdf5c70643434337c3874d417de45f83e48f7c00afaf7180e918199dde712083a3f512483e89d756f25ddafe8b14b246499fe44dd3bda1f1a580cf7af9dd35c6ddfffa2ec8af0d41b00d7ca5ed25af8e54d4bef1f9",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 12,
+        prefix: #"",
+        root: #"136bca071d530710ba622dfd66fe1afb859d4f42d45f29ce252e862a92eb10c2",
+      },
+    },
+  ]
+
+test insert_edge_case4() {
+  let trie =
+    mpf.from_root(
+      #"76ff3670f2b81017d50354ca4a78792de31adbd23f456eec41d7a8c13fcdc91b",
+    )
+  let block_hash =
+    #"04811fc306a2021340b15ce6f025db1dc3d402f0829c7ee2100ca8fdd6ed10cd"
+  let block_body = #"0c43c3addce8b95e49eb0fb906"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof4) == mpf.from_root(
+    #"a6eb3cdf9dd3da02d9463bd5cd68555ea11d6d5a77e2ece9ceb1cf6a5a9c7b27",
+  )
+}
+
+const edge_case_proof3: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"9adb4faf00cb2666b1b18dd461cbedfeb51f2d95e4158c96c222ebe84d91391eec30cd78944a11d044682818143d22b96fc31932aa2c52e00b1888c65e56dab8a53c54b7d9170432cd45530cb4f23b20d073fceaf910c296d72446eb780b12175c057d3a7768e6460dc367abaeb396095594a6cde5068afbbbd1268c0fd36d27",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"d9701403f8a22c78d8ea0aa13580427d33a09ad207000f96d2c8cc3f9049792a17d5489236013aba204e657d142a4cc1f92b98e6d8ce31dba37eb355a98befe64a1ef3c786c8bdefff9c6ff870a6db9f86115b4760396b91abe622de3f29d85618da02ae1a2daa6ef05164669740c58d4af735eca7129a5e7b12490508eef65f",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"888502234def2d4ab5ce331577c00537350807cc6411f4a713db6e7c39da756de6665ece82216244b78d1ad2218775994977d8d8337f4d0d11d3f444b80d447373dac7d204349e68dd5d4303d169f22981d016b62d7f3295284c046b70bc87fc0000000000000000000000000000000000000000000000000000000000000000",
+    },
+    Fork {
+      skip: 1,
+      neighbor: Neighbor {
+        nibble: 9,
+        prefix: #"",
+        root: #"34b8236af8370a93aa648a541efebae35dec9488f6160e324e656af0be5d374a",
+      },
+    },
+  ]
+
+test insert_edge_case3() {
+  let trie =
+    mpf.from_root(
+      #"6544f125947f9b41d6e6ad0560f7174836d987fdb404df3f379985a2f661e4b9",
+    )
+  let block_hash =
+    #"497f99bb7565d7be2828f6580161cd27cdf8f56418adde5be871b6d0a447da15"
+  let block_body =
+    #"85ff67896b3cc0f2c866bef1c51e6c00055d059cd00067c10a49c74d24277c"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof3) == mpf.from_root(
+    #"b6c45bc7651f957c7c6957e1c10439ad5878ef5c7bc147c8ab6b7e163bd32554",
+  )
+}
+
+const edge_case_proof2: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"4c54bfc322fb7bc2e49ae21bf5fa560632e3ca42b5267eb115142e291e8ada4ecd0c58152bf064f0c7834dd72f69d12651739b32caaa3c986a87937f125b500f1426fccf2a456bce3c25b43206d9b429d56515580d086a959ca730325411b3aada6ac4d7221f787b97e1ce677fdadc412e824a9816281b1259b91addeb37bb2c",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"098745f495c99b7627f559ac8ed8165e2392e2261ef8990291f13705adf78fcf3dcca881d4b45aabe746e7041f743baaa831029e7890df9587858d8be5dce648e02f31fe2936417a393df8def15d7d0c021a66cdb33c3fdda941ae70614913cb116fd5e6c499b71e229b88f5106975cbe83a8c44d3619541d7ddd7eae0a355bc",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"9732c3266e468dd27c4bd16af5a6e60c1f556bf91700f51554cfa33aa26b8d30f33c27ab7c5c85ef006c78f56ecd7e8c77c5fadd7910e9b178801d554f244977026104fc4aede0864d405db792691c4e4534b06ae7f58366b640f13ecfa549afa046a157d2e9b6c0793a506942eb8ff50dfeb7c5e7a2a51814c4b3a4d6af6fa0",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"5f3065e998b5fa89bb33d9204546c5dba2b075adc542688dcc1773a490fa739ac69ff52c5f575e9f1912664c1ebef2f9498775350b0077a6b59fe012861c3715657146a239aaea12b3091054e5846771bba6f721b1835d025fa08d1fc5c9b1c40000000000000000000000000000000000000000000000000000000000000000",
+    },
+    Leaf {
+      skip: 1,
+      key: #"2b5b0ba7a99e17d9fde58f14dee61cccda9e3e9627b2ba2732ebed551ea9eaa4",
+      value: #"3657998959985b7b75c734eb5b49d18cae9b353d00d811cb2c24ed6ed17b23d9",
+    },
+    Leaf {
+      skip: 0,
+      key: #"2b5b063719f4b7644c71adef1439c9aa78d34e684677dd61db0adffcc21797ec",
+      value: #"4e397303e05277d98701446ee62f6f02bc013721fc12efba7300fb51ea935f9f",
+    },
+  ]
+
+test insert_edge_case2() {
+  let trie =
+    mpf.from_root(
+      #"00489b47aa866ff55da4f24fa4801a6948871258fab39f22354f35b7c4f94412",
+    )
+  let block_hash =
+    #"198d70e41146654a69e08c6682310a8c35816c8584431915a0eee4a62d39eda0"
+  let block_body = #"9e36f867a374be"
+  mpf.insert(trie, block_hash, block_body, edge_case_proof2) == mpf.from_root(
+    #"b76dd0926602d6e9d28a0b3707db4622184d59c7392f5a0469bf775d9aa05f33",
+  )
+}
+
+const edge_case_proof: Proof =
+  [
+    Branch {
+      skip: 0,
+      neighbors: #"6da036230d1cdb614137b0d5a94bfe0350eae80a7a6228e1ada0025b3c4f7b7b5527cc2fa7d7d50e6059ef33bb9d71f4135265d016affaaebc48465275528b4cc47a765a2d0a90fa7efe6c4c2afb227f8fafa193d16b98afd8e0536d8f07beef9c989638ac0ebb91ce40562b449f66d80119354630bfbd3d1f51db2369a10c7b",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"d1672f79764d1e73c9784121bfcc4b77a043dd07d5769c9a041b04f421572cddb53b70e36b1ae1568c438bdd94eb7d209973e669639bf970b2356b98f4f23bbc66a5aeefc3e6796bd5559a1eba9e61a86eab048c18ec8f93a787c8ea7893c010828b7a5a3d83c8f64471a9a93a606591c3823f9b718870d1bb30f99e38cbac9b",
+    },
+    Branch {
+      skip: 0,
+      neighbors: #"dca400d830a111355a23e3c85ebccb507a7150bc26a259fce184ce63b0ec917ce2d43e656aafa0f3de6381d4c0ef65a76c263598eaf76156819bd2c321504d808b0dbee17ff39324bb913eecd66b8f49238000c1d0c22af719d51fe0f676d23e0000000000000000000000000000000000000000000000000000000000000000",
+    },
+    Leaf {
+      skip: 1,
+      key: #"5080c2f95315f3ef1f89304d94651f0f8ae2f80daa5cff26b9a7fd27813eae0b",
+      value: #"0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8",
+    },
+    Leaf {
+      skip: 0,
+      key: #"508010f4051f83d17de96eab544cd32a977e88fbe5a4b3b1274b11cce8aaf642",
+      value: #"0e5751c026e543b2e8ab2eb06099daa1d1e5df47778f7787faab45cdf12fe3a8",
+    },
+  ]
+
+test insert_edge_case() {
+  let trie =
+    mpf.from_root(
+      #"08b05f422582a099e63646ccf6ed5993c1718d0279a3269c140c1daed29f0f4b",
+    )
+  let block_hash =
+    #"3fe6f46456b9c223116533d90f9b0bf7c5da095e0c1d68af297a2a3c9709bfa7"
+  let block_body = #""
+  mpf.insert(trie, block_hash, block_body, edge_case_proof) == mpf.from_root(
+    #"ff55eab671a6e5618b10bb8702e3e5e6ab2491d50e4a93dd5255d8666a8d4e9a",
+  )
+}
+
 const proof_bitcoin_845999: Proof =
   [
     Branch {