fix: align lint role-before-use check with siblings

supertensor lint.py now rejects role= used before \stsetrole, matching
superfig and superderive lint behavior. Previously this was only caught
at TeX compile time by \stcheckrole.

SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: supertensor
-description: Create or refine clean, shape-aware figures for tensor/matrix/vector formulas or tensor code — matrix-block diagrams, entry heatmaps, row/column shard stripes, stacked 3D/4D tensors, attention, tensor/expert parallelism, broadcasting, reductions, contractions, gather/scatter and routing. Use whenever tensor shapes or axis meanings must be visually aligned with the computation. Not for plotting numeric data (loss curves, benchmark bars, scatter plots), architecture block diagrams without shapes, or generic flowcharts.
+description: Create or refine clean, shape-aware figures for tensor/matrix/vector formulas or tensor code — matrix-block diagrams, entry heatmaps, row/column shard stripes, stacked 3D/4D tensors, attention, tensor/expert parallelism, broadcasting, reductions, contractions, gather/scatter and routing. Use whenever tensor shapes or axis meanings must be visually aligned with the computation, or the user runs $supertensor. Not for plotting numeric data (loss curves, benchmark bars, scatter plots), architecture block diagrams without shapes (use superfig), stepwise rewrite figures (use superderive), or full paper notes (use superpaper).
 ---
 
 # supertensor

assets/supertensor.sty

@@ -838,6 +838,6 @@
 % ------------------------------------------------------------- signature ----
 % Optional centered subject line, outside the meaning box, low contrast.
 \newcommand{\stsignature}[2]{%
-  \node[below=2.2mm of #2, font=\scriptsize, text=black!45] (st-signature) {#1};}
+  \node[below=2.2mm of #2, font=\scriptsize, text=black!45] (#2-sig) {#1};}
 
 \endinput

scripts/lint.py

@@ -68,6 +68,14 @@ def lint(path: Path) -> list[str]:
     dimensions = check_unique(source, DIM_RE, "axis", errors)
     roles = check_unique(source, ROLE_RE, "role", errors)
 
+    for match in ROLE_KEY_RE.finditer(source):
+        role = match.group(1)
+        if role not in roles:
+            errors.append(
+                f"line {line_of(source, match.start())}: role {role!r} is used "
+                f"before \\stsetrole"
+            )
+
     formula_positions = [m.start() for m in re.finditer(r"\\sttopformula\b", source)]
     row_ends = [m.start() for m in re.finditer(r"\\strowend\b", source)]
     if not formula_positions and "allow-missing-formula" not in allowed: