lilylet: emit %-style prompt lines (period/composer/instrument) instead of [composer ...] fields; postprocess treats % as meta

app.py

@@ -170,22 +170,27 @@ def load_library ():
 	return {**load_examples(), **load_outputs()}
 
 
-_STYLE_LINE_RE = re.compile(r'^\[(composer|genre|instrument)\s+".*"\]\s*$')
+# A managed style line in the new `--styles-in-comments` format: a leading `%<value>`
+# comment carrying period / composer / instrumentation (one per line). `sync_prompt`
+# regenerates these from the dropdowns; any other line the user typed is preserved.
+_STYLE_LINE_RE = re.compile(r'^%(?!%).*$')
 
 
 def sync_prompt (composer, genre, instrument, current):
 	'''Rewrite the metadata-prompt text from the three style dropdowns.
 
-	The `[composer/genre/instrument "..."]` lines are regenerated from the
-	dropdowns and placed at the top; any other lines the user typed (e.g.
-	`[key "..."]`) are preserved below in their original order.
+	The model is trained on the `--styles-in-comments` format: style is carried by
+	leading `%<value>` comment lines, ordered period/composer/instrumentation (matching
+	abc2lilylet's catalogCommentLines: %<genre> / %<composer> / %<instrument>). These
+	are regenerated from the dropdowns and placed at the top; any other line the user
+	typed (e.g. a `[staves "..."]` header) is preserved below in its original order.
 	'''
 	lines = []
-	for field, value in (('composer', composer), ('genre', genre), ('instrument', instrument)):
+	for value in (genre, composer, instrument):
 		value = (value or '').strip()
 		if value:
-			lines.append(f'[{field} "{value}"]')
-	# keep every line that isn't one of the three managed style lines
+			lines.append(f'%{value}')
+	# keep every line that isn't one of the managed `%<style>` lines
 	for ln in (current or '').splitlines():
 		if not _STYLE_LINE_RE.match(ln.strip()):
 			if ln.strip():

lilyscript/postprocess.py

@@ -39,7 +39,9 @@ def postprocess (text: str) -> str:
 			pending = m.group(1)
 			ln = _STREAM_RE.sub('', ln).rstrip()
 
-		is_meta = ln.startswith('[') and ln.endswith(']')
+		# metadata lines: `[field "..."]` headers and leading `%<style>` comments
+		# (the --styles-in-comments format). Both belong to the meta block.
+		is_meta = (ln.startswith('[') and ln.endswith(']')) or (ln.startswith('%') and not ln.startswith('%%'))
 		# blank line once the metadata block ends and the body begins
 		if not meta_done and out and not is_meta and ln:
 			out.append('')