Add virtual attribute for automatically generated edges

- Introduced a `virtual` attribute for automatically generated section transitions and backlinks in the graph edge definitions, indicating their virtual nature.
- Updated documentation to reflect the addition of the `virtual` attribute for both section transitions and backlinks, clarifying its implications for scoring in the retriever.
- Enhanced the understanding of edge types by specifying that these automatically generated edges will receive a penalty during scoring.

app/core/graph/graph_derive_edges.py

@@ -695,6 +695,7 @@ def build_edges_for_note(
                 "source_hint": "schema_default",
                 "confidence": PROVENANCE_PRIORITY.get("schema_default", 0.85),
                 "is_internal": True,  # Explizit als Intra-Note-Edge markieren
+                "virtual": True,  # WP-26 v1.4: Automatisch generierte Section-Transitions sind virtuell
                 "section_transition": f"{current_type}->{next_type}"  # Debug-Info
             }))
 
@@ -1102,6 +1103,7 @@ def build_edges_for_note(
                 "source_hint": "automatic_backlink",
                 "confidence": PROVENANCE_PRIORITY.get("derived:backlink", 0.8),
                 "is_internal": True,
+                "virtual": True,  # WP-26 v1.4: Automatisch generierte Backlinks sind virtuell
                 "original_edge_kind": kind  # Debug-Info: Welcher Edge-Type wurde invertiert
             })
             

docs/06_Roadmap/06_LH_Section_Types_Intra_Note_Edges.md

@@ -611,6 +611,7 @@ default_edge = topology["typical"][0]  # "resulted_in"
     "provenance": "rule",
     "rule_id": "derived:intra_note_backlink",
     "source_hint": "automatic_backlink",
+    "virtual": True,  # Automatisch generierte Backlinks sind virtuell
     "original_edge_kind": "derives"  # Debug-Info
 }
 ```
@@ -638,7 +639,8 @@ default_edge = topology["typical"][0]  # "resulted_in"
     "scope": "chunk",
     "is_internal": True,
     "provenance": "rule",
-    "rule_id": "inferred:section_transition"
+    "rule_id": "inferred:section_transition",
+    "virtual": True  # Automatisch generierte Section-Transitions sind virtuell
 }
 
 # Backlink (automatisch erzeugt)
@@ -649,7 +651,8 @@ default_edge = topology["typical"][0]  # "resulted_in"
     "scope": "chunk",
     "is_internal": True,
     "provenance": "rule",
-    "rule_id": "derived:intra_note_backlink"
+    "rule_id": "derived:intra_note_backlink",
+    "virtual": True  # Automatisch generierte Backlinks sind virtuell
 }
 ```
 
@@ -657,6 +660,8 @@ default_edge = topology["typical"][0]  # "resulted_in"
 - Backlinks werden **nur** erstellt, wenn noch kein inverser Edge existiert
 - Backlinks haben immer `scope: "chunk"` (nicht `scope: "note"`)
 - Backlinks werden **nach** der Deduplizierung erstellt, um Duplikate zu vermeiden
+- Backlinks haben `virtual: True` (automatisch generierte Edges erhalten eine Penalty von 0.5 beim Scoring im Retriever)
+- Automatische Section-Transition-Edges haben ebenfalls `virtual: True`
 
 ### 4.4 Retriever-Anpassungen