add OKF package api

surfsense_backend/app/services/okf/__init__.py

@@ -0,0 +1,56 @@
+"""Open Knowledge Format (OKF v0.1) serialization for the SurfSense KB.
+
+Single source of truth for turning documents and folders into OKF concepts,
+``index.md`` listings and ``log.md`` logs. Pure KB-layer functions; every
+consumer (ZIP export, REST, MCP, agents) calls in.
+
+The OKF-native model: ``Document`` rows are canonical, and frontmatter is
+*derived* from their columns on read (never stored), so rows are conformant by
+construction. Chunks and embeddings are a *derived*, rebuildable search
+projection - never a source of truth.
+
+Spec: https://github.com/GoogleCloudPlatform/knowledge-catalog/blob/main/okf/SPEC.md
+"""
+
+from app.services.okf.serializer import (
+    INDEX_FILENAME,
+    LOG_FILENAME,
+    ConceptRef,
+    LogEntry,
+    SubdirRef,
+    build_frontmatter,
+    document_to_concept,
+    folder_to_index,
+    folder_to_log,
+    render_frontmatter,
+)
+from app.services.okf.type_mapping import okf_resource, okf_type
+from app.services.okf.validator import (
+    RECOMMENDED_FRONTMATTER_KEYS,
+    REQUIRED_FRONTMATTER_KEYS,
+    is_conformant_concept,
+    parse_frontmatter,
+    validate_bundle,
+    validate_concept,
+)
+
+__all__ = [
+    "INDEX_FILENAME",
+    "LOG_FILENAME",
+    "ConceptRef",
+    "LogEntry",
+    "SubdirRef",
+    "build_frontmatter",
+    "document_to_concept",
+    "folder_to_index",
+    "folder_to_log",
+    "render_frontmatter",
+    "okf_resource",
+    "okf_type",
+    "RECOMMENDED_FRONTMATTER_KEYS",
+    "REQUIRED_FRONTMATTER_KEYS",
+    "is_conformant_concept",
+    "parse_frontmatter",
+    "validate_bundle",
+    "validate_concept",
+]