Pablan, as it stands

Self-hosted knowledge management for SMEs: a split-screen Markdown editor
whose sections an LLM refines while you write, and RAG question answering
over the documents that result. FastAPI + Postgres/pgvector on the back,
SvelteKit on the front, everything OpenAI-compatible and self-hostable.

Squashed into a single commit; the development history stays local.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CA43ZJda8Rbp2hKXNy8f6b

backend/app/api/templates/blueprints.py

@@ -0,0 +1,67 @@
+"""A template's blueprint: parsing it, and keeping its id unique.
+
+The config id is a slug, not a row id — it is what documents record as their
+origin and what the catalog matches on, so two rows must never share one.
+Three endpoints need that rule (add from catalog, save from the builder,
+duplicate), which is why it is written once here.
+"""
+
+import uuid
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.authoring.schema import AuthoringTemplate
+from app.errors import ApiError
+from app.models import Template
+from app.template_import import TemplateImportError, parse_template
+
+
+def parse_or_422(source: str) -> AuthoringTemplate:
+    """YAML in, validated blueprint out. The parse error is the message: it
+    already says which field is wrong, and an admin is the one reading it."""
+    try:
+        return parse_template(source)
+    except TemplateImportError as exc:
+        raise ApiError(422, str(exc), "invalid_template") from None
+
+
+async def taken_config_ids(db: AsyncSession) -> set[str]:
+    return set((await db.execute(select(Template.config["id"].astext))).scalars().all())
+
+
+def unique_config_id(base: str, taken: set[str], *, suffix: str = "") -> str:
+    """`base`, or `base-2`, `base-3` … until it is free.
+
+    `suffix` marks derived ids (a duplicate becomes `base-kopie`), so a copy
+    reads as a copy in the one place ids are visible.
+    """
+    stem = f"{base}{suffix}"
+    candidate = stem
+    counter = 2
+    while candidate in taken:
+        candidate = f"{stem}-{counter}"
+        counter += 1
+    return candidate
+
+
+async def ensure_config_id_free(
+    db: AsyncSession, config_id: str, *, except_row: uuid.UUID
+) -> None:
+    """Refuse an edit that would move a config id onto a DIFFERENT row.
+
+    Editing keeps the id stable, so a clash is never the row's own id — it
+    means someone would silently steal another template's identity.
+    """
+    clash = (
+        await db.execute(
+            select(Template.id).where(
+                Template.config["id"].astext == config_id,
+                Template.id != except_row,
+            )
+        )
+    ).scalar_one_or_none()
+    if clash is not None:
+        raise ApiError(
+            409, f"Another template already uses the id '{config_id}'.", "id_taken"
+        )