All for smaller files

this is called a package? alright sure

src/wf_authoring/builder/ids.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+import re
+from collections.abc import Iterable
+
+from .refs import StepRef, step_id
+
+
+def slug_id(value: str) -> str:
+    """Convert a display name into a stable, readable workflow step id."""
+    slug = re.sub(r"[^0-9A-Za-z_]+", "_", value).strip("_").lower()
+    return slug or "step"
+
+
+def next_step_id(base: str, nodes: Iterable[StepRef]) -> str:
+    """Return a stable unused step id based on the requested base name."""
+    used_ids = {step_id(node) for node in nodes}
+    if base not in used_ids:
+        return base
+    suffix = 2
+    while f"{base}_{suffix}" in used_ids:
+        suffix += 1
+    return f"{base}_{suffix}"