fix: procedural KB import — add title field, correct step types, validation gate

- _build_procedural_tree now maps AI node types (step, action, warning) to
  valid procedural types (procedure_step, section_header, procedure_end)
- Generates 'title' field from content text — fixes "Unnamed step" in editor
- Auto-appends procedure_end step if AI didn't generate one
- Adds procedural validation gate at commit endpoint (same as troubleshooting)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/api/endpoints/kb_accelerator.py

@@ -28,6 +28,7 @@ from app.core.rate_limit import limiter
 from app.core.subscriptions import get_plan_limits
 from app.core.ai_quota_service import get_user_plan
 from app.core.ai_tree_validator import validate_generated_tree
+from app.core.tree_validation import validate_procedural_structure
 from app.core.kb_extraction_service import extract_text
 from app.core.kb_conversion_service import convert_document
 from app.models.kb_import import KBImport, KBImportNode
@@ -561,6 +562,22 @@ async def commit_import(
                     "validation_errors": validation_errors,
                 },
             )
+    else:
+        # Procedural/maintenance validation
+        is_valid, proc_errors = validate_procedural_structure(tree_structure)
+        if not is_valid:
+            error_messages = [e.get("message", str(e)) for e in proc_errors]
+            logger.warning(
+                "KB commit blocked: procedural flow failed validation with %d errors: %s",
+                len(proc_errors), "; ".join(error_messages[:5]),
+            )
+            raise HTTPException(
+                status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+                detail={
+                    "message": "The converted flow has structural issues that need to be fixed before committing.",
+                    "validation_errors": error_messages,
+                },
+            )
 
     # Build intake_form for procedural flows
     intake_form = None
@@ -881,17 +898,59 @@ def _demote_decision_to_action(node: dict, siblings: list[dict], index: int) ->
 # Delete the broken _repair_tree and replace with the working version
 # by removing the first broken attempt
 def _build_procedural_tree(nodes: list[KBImportNode]) -> dict:
-    """Build a procedural tree_structure from import nodes."""
+    """Build a procedural tree_structure from import nodes.
+
+    Maps AI node types to valid procedural step types:
+    - step/action/warning → procedure_step
+    - section_header → section_header
+    Adds a procedure_end step at the end if missing.
+    Each step requires 'title' (from content text) and 'content' fields.
+    """
+    # Type mapping from AI output to valid step types
+    TYPE_MAP = {
+        "step": "procedure_step",
+        "action": "procedure_step",
+        "warning": "procedure_step",
+        "question": "procedure_step",
+        "resolution": "procedure_step",
+        "section_header": "section_header",
+        "procedure_step": "procedure_step",
+        "procedure_end": "procedure_end",
+    }
+
     steps = []
     for node in sorted(nodes, key=lambda n: n.node_order):
         content = node.content
-        step = {
+        raw_type = node.node_type
+        step_type = TYPE_MAP.get(raw_type, "procedure_step")
+
+        step_content = content.get("content", "")
+        step_title = content.get("title") or content.get("question") or step_content[:80] or "Step"
+
+        step: dict = {
             "id": content.get("original_id", str(node.id)),
-            "type": node.node_type,
-            "content": content.get("content", ""),
+            "type": step_type,
+            "title": step_title,
+            "content": step_content,
         }
+
+        # Preserve content_type if present
+        content_type = content.get("content_type")
+        if content_type:
+            step["content_type"] = content_type
+
         steps.append(step)
 
+    # Ensure a procedure_end exists at the end
+    has_end = any(s["type"] == "procedure_end" for s in steps)
+    if not has_end and steps:
+        steps.append({
+            "id": "procedure-end",
+            "type": "procedure_end",
+            "title": "Procedure Complete",
+            "content": "All steps have been completed.",
+        })
+
     return {
         "id": "root",
         "type": "procedural",