diff --git a/aicirt/src/main.rs b/aicirt/src/main.rs
index a2ce80b4..5a7ef23f 100644
--- a/aicirt/src/main.rs
+++ b/aicirt/src/main.rs
@@ -13,10 +13,12 @@ use crate::{
 };
 use aici_abi::{
     bytes::limit_str, toktree::TokTrie, Branch, MidProcessArg, ProcessResultOffset, SeqId,
+    TokenizerEnv,
 };
 use aicirt::{bintokens::find_tokenizer, futexshm::ServerChannel, shm::ShmAllocator, *};
 use anyhow::{anyhow, ensure, Result};
 use base64::{self, Engine as _};
+use bintokens::ByteTokenizerEnv;
 use clap::Parser;
 use hex;
 use hostimpl::GlobalInfo;
@@ -1099,15 +1101,17 @@ fn bench_hashmap() {
 
 fn save_tokenizer(cli: &Cli) {
     let filename = cli.save_tokenizer.as_deref().unwrap();
+
     let tokenizer = find_tokenizer(&cli.tokenizer).unwrap();
-    let tokens = tokenizer.token_bytes();
+    let env = ByteTokenizerEnv::new(tokenizer);
 
+    let tokens = env.tokenizer.token_bytes();
     log::info!(
         "TokTrie building: {:?} wl={}",
-        tokenizer.tokrx_info(),
+        env.tokenizer.tokrx_info(),
         tokens.len()
     );
-    let trie = TokTrie::from(&tokenizer.tokrx_info(), &tokens);
+    let trie = &env.tok_trie;
     trie.check_against(&tokens);
 
     let bytes = trie.serialize();
@@ -1119,6 +1123,27 @@ fn save_tokenizer(cli: &Cli) {
 
     std::fs::write(filename, &bytes).unwrap();
     println!("wrote {}, {} bytes", filename, bytes.len());
+
+    if false {
+        for (a, abytes) in tokens.iter().enumerate() {
+            let mut ts = trie.alloc_token_set();
+            let a = a as u32;
+            for (b, bbytes) in tokens.iter().enumerate() {
+                let b = b as u32;
+                let mut bytes = abytes.to_vec();
+                bytes.extend_from_slice(bbytes);
+                let r = env.tokenize_bytes(&bytes);
+                if r.len() == 2 && r[0] == a && r[1] == b {
+                    ts.allow_token(b);
+                }
+            }
+
+            let neg = ts.num_set() > 15000;
+            let ts = if neg { ts.negated() } else { ts };
+            let elts = ts.iter().collect::<Vec<_>>();
+            println!("{a} ==> {neg} {elts:?}");
+        }
+    }
 }
 
 fn install_from_cmdline(cli: &Cli, wasm_ctx: WasmContext, shm: Rc<ShmAllocator>) {
diff --git a/scripts/random/parse-tokenizer-automaton.js b/scripts/random/parse-tokenizer-automaton.js
new file mode 100644
index 00000000..78d805ac
--- /dev/null
+++ b/scripts/random/parse-tokenizer-automaton.js
@@ -0,0 +1,82 @@
+const fs = require("fs")
+
+const nevers = [0, 1, 2, 16, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 32000]
+
+const MIN_DELTA = 0
+const MAX_DELTA = MIN_DELTA + 2
+
+function diff(a, b) {
+    let i = 0
+    let j = 0
+    let delta = 0
+    while (i < a.length || j < b.length) {
+        if (i < a.length && j < b.length) {
+            if (a[i] == b[j]) {
+                i++;
+                j++;
+            } else if (a[i] < b[j]) {
+                delta++;
+                i++;
+            } else {
+                delta++;
+                j++;
+            }
+        } else if (i < a.length) {
+            delta++;
+            i++;
+        } else {
+            delta++;
+            j++;
+        }
+
+        if (delta > MAX_DELTA) {
+            return delta;
+        }
+    }
+    return delta;
+}
+
+const buckets = []
+let no_bucket_size = 0
+
+fs.readFileSync("tmp/tokens.txt", "utf8").split("\n").forEach((line, i) => {
+    const m = /^(\d+) ==> (true|false) (.*)/.exec(line);
+    if (!m) return
+    const tokid = +m[1];
+    let elts = Array.from(JSON.parse(m[3]));
+    const neg = m[2] == "true";
+    const isAllowed = (e) => {
+        if (neg) return !elts.includes(e);
+        return elts.includes(e);
+    }
+
+    const nev = nevers.find(e => isAllowed(e));
+    if (nev) {
+        console.log(tokid, "N", nev);
+    }
+
+    const empty = elts.length == 0 && !neg;
+    if (empty) {
+        //console.log(tokid, "E");
+    } else {
+        if (!neg) {
+            console.log(tokid, "A", elts.length);
+        } else {
+            let existing = false
+            elts = elts.filter(e => !nevers.includes(e));
+            for (const b of buckets) {
+                if (diff(elts, b) <= MIN_DELTA) {
+                    existing = true;
+                    break;
+                }
+            }
+            if (!existing) {
+                buckets.push(elts);
+            }
+            no_bucket_size += elts.length;
+            console.log(tokid, "F", elts.length, buckets.length);
+        }
+    }
+})
+
+console.log(buckets.reduce((a, b) => a + b.length, 0), no_bucket_size)
diff --git a/scripts/tokenizer-stats.js b/scripts/tokenizer-stats.js
index 5475b2d2..e65f8d5b 100755
--- a/scripts/tokenizer-stats.js
+++ b/scripts/tokenizer-stats.js
@@ -133,6 +133,18 @@ function stats(fn) {
   const ones = byteCounts.map((c, i) => c == 1 ? i : undefined).filter(x => x !== undefined)
   const zeros = byteCounts.map((c, i) => c == 0 ? i : undefined).filter(x => x !== undefined)
   console.log("Byte counts:", { ones, zeros })
+
+  const merged = {}
+  for (const merge of tokenizer.model.merges) {
+    const words = merge.split(' ');
+    if (words.length != 2) {
+      console.log("Bad merge: ", merge)
+    }
+    merged[words[0]] = true
+    merged[words[1]] = true
+  }
+  console.log("Num merges:", tokenizer.model.merges.length)
+  console.log("Num merged tokens:", Object.keys(merged).length)
 }
 
 function permute(arr) {