Update print view and documentation for logical feeds

docs/circuit-list-editor-api.md

@@ -67,10 +67,13 @@ Prüfsumme; Ersetzen übernimmt die Grobbilanzen atomar und mit Undo/Redo,
 Duplizieren vergibt neue IDs. Transferformat 1 bleibt ohne Grobbilanzen
 importierbar.
 
-Das aktuelle Projekt-Snapshot-Schema 8 enthält außerdem die optionale
-Netto-Raumfläche `rooms[].areaM2`. Snapshot-Versionen 1–7 werden dafür mit
+Das aktuelle Projekt-Snapshot-Schema 9 enthält die logischen Einspeisungsverweise
+der Verteilungen; Versionen 1–8 werden mit leeren Verweisen hochgestuft. Schema 8
+enthält außerdem die optionale Netto-Raumfläche `rooms[].areaM2`.
+Snapshot-Versionen 1–7 werden dafür mit
 `areaM2 = null` hochgestuft. Restore, Export und Import erhalten vorhandene
-Flächen; eine eigene Transferformat-Version ist nicht nötig, weil Format 2 den
+Flächen und Einspeisungsverweise; beim Duplizieren werden Board- und Circuit-IDs
+neu zugeordnet. Eine eigene Transferformat-Version ist nicht nötig, weil Format 2 den
 versionierten Projektsnapshot einbettet.
 
 The public dispatcher supports the Circuit and CircuitDeviceRow commands
@@ -254,23 +257,30 @@ commands. Endpoints, payloads and calculation rules: `docs/estimate-balance.md`.
   - stale revisions return `409 PROJECT_REVISION_CONFLICT`
 - `PUT /projects/:projectId/distribution-boards/:distributionBoardId`
   - body:
-    `{ "floorId": null, "supplyType": "AV", "simultaneityFactor": 1, "expectedRevision": 13 }`
+    `{ "floorId": null, "supplyType": "AV", "simultaneityFactor": 1, "feedingDistributionBoardId": "board_hv", "feedingCircuitId": "circuit_out", "expectedRevision": 13 }`
   - optional info-card fields: `boardNumber` (max. 50), `location`,
     `fedFrom` (max. 200 each) and `remark` (max. 2000); strings are trimmed
     and an empty string is stored as `null`
-  - executes `distribution-board.update`; all submitted values, including the
+  - `feedingDistributionBoardId` and `feedingCircuitId` are optional nullable
+    fields. A feeding circuit requires a feeding board and must belong to it;
+    self-links and cycles are rejected. A board-only link creates hierarchy
+    without assigning its load to an upstream circuit.
+  - executes `distribution-board.update` schema version 2; all submitted values, including the
     submitted info fields, are restored together by persistent Undo/Redo
-  - `fedFrom` is free text until the logical feed link is modeled
+  - `fedFrom` remains free text for external feeds such as HAK, metering,
+    transformer or generator and for supplementary notes
 - `POST /projects/:projectId/distribution-boards/:distributionBoardId/copy`
   - body: `{ "name": "UV-02 Kopie", "expectedRevision": 14 }`
   - duplicates the complete distribution-board subtree with new owning UUIDs
-    while preserving project-device and room links
+    while preserving project-device, room and incoming feeding links
   - response includes the new `distributionBoard`, its `circuitList`, the
     revision and current history state
 - `DELETE /projects/:projectId/distribution-boards/:distributionBoardId`
   - body: `{ "expectedRevision": 15 }`
   - removes the complete, exactly captured distribution-board subtree in one
     transaction
+  - rejects deletion while another board references this board or one of its
+    circuits as a feeder; circuit and populated-group deletion use the same guard
   - response includes `distributionBoardId`, the revision and current history
     state
 - Copy and deletion use `distribution-board.insert-subtree` and
@@ -327,12 +337,17 @@ commands. Endpoints, payloads and calculation rules: `docs/estimate-balance.md`.
 
 ### Tree Endpoint
 
+- `GET /projects/:projectId/circuit-trees`
+  - returns all circuit trees for one project from one project-wide read and is
+    used by the print view and feeding-board selection
 - `GET /projects/:projectId/circuit-lists/:circuitListId/tree`
 - Purpose: returns fixed header components, grouped sections with optional
   protection components, complete circuit/device-row blocks and auxiliary
   footer components. Circuit and component protection devices use their
   separate one-to-one DTOs. Calculated row, circuit, section and board totals
-  remain included.
+  remain included. Circuit totals contain the demand of linked downstream
+  boards. `downstreamBoardLoads` exposes those contributions as read-only rows;
+  `feedingReference` resolves the current board/circuit labels by id.
 
 Response sketch: