diff --git a/lib/song.py b/lib/song.py
index 5d80027..ce3b859 100644
--- a/lib/song.py
+++ b/lib/song.py
@@ -328,10 +328,15 @@ def chord_template_to_wire(ct: ChordTemplate) -> dict:
     if ct.voicing:
         out["voicing"] = ct.voicing
     # CAGED shape + guide tones (§6.6) — default-omitted, mirroring voicing.
-    if ct.caged:
-        out["caged"] = ct.caged
-    if ct.guide_tones:
-        out["guideTones"] = list(ct.guide_tones)
+    # Sanitize on EMIT too (not just on decode): a directly-constructed template
+    # must not be able to write a non-enum `caged` or an out-of-range `guideTone`
+    # to the wire (the spec constrains caged to C/A/G/E/D and guideTones to 0..11).
+    _caged = _sanitize_caged(ct.caged)
+    if _caged:
+        out["caged"] = _caged
+    _guide_tones = _sanitize_guide_tones(ct.guide_tones)
+    if _guide_tones:
+        out["guideTones"] = _guide_tones
     return out
 
 
diff --git a/tests/test_song.py b/tests/test_song.py
index 92af496..b98cae0 100644
--- a/tests/test_song.py
+++ b/tests/test_song.py
@@ -514,6 +514,20 @@ def test_template_caged_tolerates_malformed(bad):
     assert arr.chord_templates[0].caged == ""
 
 
+def test_template_caged_guide_tones_sanitized_on_emit():
+    """A directly-constructed template can't write an invalid caged / out-of-range
+    guideTone to the wire — the emitter sanitizes, not just the decoder."""
+    ct = ChordTemplate(name="Am", fingers=[-1] * 6, frets=[-1] * 6,
+                       caged="X", guide_tones=[3, 99, -1, "x", True])
+    wire = chord_template_to_wire(ct)
+    assert "caged" not in wire            # non-enum dropped, not emitted
+    assert wire["guideTones"] == [3]      # only the valid in-range int survives
+    # A wholly-invalid guideTones list omits the key entirely.
+    ct2 = ChordTemplate(name="Am", fingers=[-1] * 6, frets=[-1] * 6,
+                        guide_tones=[42, "nope"])
+    assert "guideTones" not in chord_template_to_wire(ct2)
+
+
 def test_template_guide_tones_round_trip():
     """A non-empty guideTones list survives the template wire + round-trip."""
     ct = ChordTemplate(name="G7", display_name="G7", fingers=[3, 2, 0, 0, 0, 1],