diff --git a/models.yaml b/models.yaml
index 724c3ee0..c75aa669 100644
--- a/models.yaml
+++ b/models.yaml
@@ -718,8 +718,8 @@ models:
     precision: fp16
     filename: urd-diac-base-1.0-fp16.zip
     url: https://github.com/interscript/interscript-models/releases/download/urd-diac-base-1.0/urd-diac-base-1.0-fp16.zip
-    sha256: 8058220d72df76b31260358070499c2cdb504f030fa10259b48aa05c7caf5711
-    size: 1347487633
+    sha256: 6818469cbeeb58b822279c06e921669e4e79dc174d0b54c37a1be34687068252
+    size: 1347488093
     metrics:
     - name: cer
       value: 3.57
@@ -736,8 +736,8 @@ models:
     precision: fp16
     filename: fas-diac-base-1.0-fp16.zip
     url: https://github.com/interscript/interscript-models/releases/download/fas-diac-base-1.0/fas-diac-base-1.0-fp16.zip
-    sha256: 974eddac04c64230ae0669103dd053a3ded9d2bc76ec51d3b50cb2a9ac240e12
-    size: 711254175
+    sha256: 620b31ab96e6d7588d583fa5119406ea7c08506d483cc8ee253b3c479c6d87f0
+    size: 711254463
     metrics:
     - name: cer
       value: 0.603
diff --git a/tools/normalize_fp16_io.py b/tools/normalize_fp16_io.py
new file mode 100644
index 00000000..32034408
--- /dev/null
+++ b/tools/normalize_fp16_io.py
@@ -0,0 +1,121 @@
+"""WO79 — normalize fp16 IMF graphs to fp32 graph IO (weights stay fp16).
+
+The fp16 export left last_hidden_state / encoder_hidden_states / logits
+in float16. Python ORT transparently widens fp16->fp32 (the reference
+path); every other runtime breaks. This tool wraps fp16 graph outputs
+in Cast(to=FLOAT) and feeds fp32 decoder inputs through an internal
+Cast(to=FLOAT16), so all graph IO is fp32 while the math stays the
+reference math. Member digests in metadata.yaml are recomputed.
+
+Usage: python tools/normalize_fp16_io.py model.zip   # in place
+"""
+from __future__ import annotations
+
+import hashlib
+import shutil
+import sys
+import tempfile
+import zipfile
+from pathlib import Path
+
+import onnx
+import yaml
+from onnx import TensorProto, helper
+
+IO_TYPES = {TensorProto.FLOAT: "fp32", TensorProto.FLOAT16: "fp16"}
+
+
+def _dims(t) -> list:
+    return [d.dim_value if d.HasField("dim_value") else d.dim_param
+            for d in t.shape.dim]
+
+
+def widen_outputs(model: onnx.ModelProto) -> bool:
+    g = model.graph
+    changed = False
+    for out in list(g.output):
+        t = out.type.tensor_type
+        if t.elem_type != TensorProto.FLOAT16:
+            continue
+        orig = out.name
+        raw = orig + "__raw"
+        out.name = raw
+        for n in g.node:
+            for i, x in enumerate(n.output):
+                if x == orig:
+                    n.output[i] = raw
+        g.output.append(helper.make_tensor_value_info(
+            orig, TensorProto.FLOAT, _dims(t)))
+        g.node.append(helper.make_node("Cast", [raw], [orig],
+                                       to=TensorProto.FLOAT))
+        # keep the raw fp16 tensor internal: the graph exposes exactly
+        # one fp32 output per original output
+        g.output.remove(out)
+        changed = True
+    return changed
+
+
+def narrow_input(model: onnx.ModelProto, name: str) -> bool:
+    """Declare `name` as fp32 IO; cast to fp16 for the internal ops."""
+    g = model.graph
+    inp = next((i for i in g.input if i.name == name), None)
+    if inp is None or inp.type.tensor_type.elem_type != TensorProto.FLOAT16:
+        return False
+    internal = name + "__f16"
+    inp.type.tensor_type.elem_type = TensorProto.FLOAT
+    consumers = [n for n in g.node if name in n.input]
+    for n in consumers:
+        for i, x in enumerate(n.input):
+            if x == name:
+                n.input[i] = internal
+    g.node.insert(0, helper.make_node("Cast", [name], [internal],
+                                      to=TensorProto.FLOAT16))
+    return True
+
+
+def normalize_zip(path: Path) -> None:
+    tmp = Path(tempfile.mkdtemp())
+    with zipfile.ZipFile(path) as z:
+        names = z.namelist()
+        meta = yaml.safe_load(z.read("metadata.yaml"))
+        graphs = {}
+        for member, digest in list((meta.get("sha256") or {}).items()):
+            model = onnx.load_model_from_string(z.read(member))
+            touched = widen_outputs(model)
+            touched |= narrow_input(model, "encoder_hidden_states")
+            if touched:
+                onnx.checker.check_model(model)
+                graphs[member] = model.SerializeToString()
+                print(f"{member}: IO normalized to fp32")
+            else:
+                print(f"{member}: already fp32 IO")
+        members = {n: z.read(n) for n in names}
+
+    for member, blob in graphs.items():
+        members[member] = blob
+        meta["sha256"][member] = hashlib.sha256(blob).hexdigest()
+
+    buf = io_bytes(members, meta)
+    digest = hashlib.sha256(buf).hexdigest()
+    shutil.copyfile(path, path.with_suffix(".zip.bak"))
+    path.write_bytes(buf)
+    print(f"rewrote {path}: zip sha256 {digest} (prior digest backed up "
+          f"as {path.with_suffix('.zip.bak').name})")
+
+
+def io_bytes(members: dict, meta: dict) -> bytes:
+    import io
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, "w", zipfile.ZIP_DEFLATED) as z:
+        for name, blob in members.items():
+            if name == "metadata.yaml":
+                z.writestr(name, yaml.safe_dump(
+                    meta, allow_unicode=True, sort_keys=False))
+            else:
+                z.writestr(name, blob)
+    return buf.getvalue()
+
+
+if __name__ == "__main__":
+    for arg in sys.argv[1:]:
+        normalize_zip(Path(arg))