diff --git a/AGENTS.md b/AGENTS.md
index 6332166..0b7077d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -299,6 +299,12 @@ objects as one external-only row (`manualQuantity = 0`) into an existing
 circuit. Its history-only inverse removes the row only while its complete
 snapshot and exact object-link set remain unchanged. Ordinary detach continues
 to preserve the row.
+`external-object.assign-to-new-circuit` atomically inserts a preplanned circuit
+with stable BMK/UUIDs, derived voltage, one external-only row, required default
+protection and its external object links. Its history-only inverse requires the
+complete unchanged circuit snapshot and exact link set. Redo never recalculates
+the BMK. All three external assignment stores share
+`external-object-assignment.persistence.ts` for compatibility and link safety.
 Confirmed initial state is written only through
 `external-import.apply-initial`. The command rechecks configuration version,
 original-byte SHA-256, parsed matrix, complete IFCGUID/source values, explicit
diff --git a/docs/circuit-list-editor-known-limitations.md b/docs/circuit-list-editor-known-limitations.md
index 0a7b076..4f7f660 100644
--- a/docs/circuit-list-editor-known-limitations.md
+++ b/docs/circuit-list-editor-known-limitations.md
@@ -10,10 +10,10 @@
   through the project page with persistent Undo/Redo. Automatic snapshots are
   created every 25 revisions and only their newest 12 entries are retained.
 - The Revit/CSV foundation and confirmed initial import are implemented.
-  Existing-row assignment, move and detach and creation of an external-only row
-  in an existing circuit have atomic persistent commands. Their editor UI, the
-  new-circuit path, follow-up import, conflict review and return export are
-  pending.
+  Existing-row assignment, move and detach plus creation of an external-only
+  row in an existing or newly created circuit have atomic persistent commands.
+  Their API planning and editor UI, follow-up import, conflict review and return
+  export are pending.
 - Persistence currently targets local SQLite; PostgreSQL is an architectural option, not an implemented runtime.
 - The global device library supports basic CRUD and copy operations, but has no
   versioning, permissions or controlled synchronization model.
diff --git a/docs/current-architecture.md b/docs/current-architecture.md
index fb4f2ee..a0282de 100644
--- a/docs/current-architecture.md
+++ b/docs/current-architecture.md
@@ -559,6 +559,17 @@ und löscht die erzeugte Row nur, wenn sie und ihre Linkmenge unverändert sind.
 Der Löschbefehl ist ausschließlich für die Projekthistorie zugelassen; eine
 normale spätere Trennung lässt die Row gemäß der allgemeinen Zuordnungsregel
 bestehen.
+`external-object.assign-to-new-circuit` erzeugt einen neuen Stromkreis mit
+vorab festgeschriebenem BMK, abgeleiteter Projektspannung, genau einer
+externen Row und verpflichtendem Standardschutz zusammen mit den Objektlinks.
+Verteilungs-, Gruppen-, Raum-, Mengen- und Planungsregeln werden vor dem Insert
+gegen den aktuellen Projektstand geprüft. Der historische Gegenbefehl ist kein
+allgemeiner Löschpfad: Er entfernt den vollständigen Circuit-Teilbaum nur bei
+unverändertem Snapshot und unveränderter Objektlinkmenge. Redo verwendet exakt
+dieselben IDs, dasselbe BMK und denselben Schutzsnapshot.
+Die drei Zuordnungsadapter teilen sich
+`external-object-assignment.persistence.ts` für Snapshotvergleich,
+Kompatibilitätsregeln und link-sichere Updates.
 `GET` und `PUT /api/projects/:projectId/external-csv/configuration` lesen oder
 ändern die Konfiguration; der PUT plant Identität und nächsten
 Konfigurationsstand serverseitig und verwendet den typisierten Command.
diff --git a/docs/spec/revit-csv-phase-14-audit-and-plan.md b/docs/spec/revit-csv-phase-14-audit-and-plan.md
index ffc1b45..b721c3a 100644
--- a/docs/spec/revit-csv-phase-14-audit-and-plan.md
+++ b/docs/spec/revit-csv-phase-14-audit-and-plan.md
@@ -205,9 +205,9 @@ bleiben und dürfen spätere Quellstände nicht erneut auswerten.
 - `external-object.update-row-assignment`: Ein oder mehrere Objekte einer
   bestehenden Row zuweisen, zwischen bestehenden Rows verschieben oder lösen
   und alle betroffenen materialisierten Mengen atomar aktualisieren.
-- `external-model-object.assign-to-new-row`: stabile neue Row einfügen,
+- `external-object.assign-to-new-row`: stabile neue Row einfügen,
   Objekte verknüpfen und gegebenenfalls den Reserve-Status aktualisieren.
-- `external-model-object.assign-to-new-circuit`: stabilen Circuit samt Schutz,
+- `external-object.assign-to-new-circuit`: stabilen Circuit samt Schutz,
   Row und Objektlinks in einem Schritt einfügen. Das geplante BMK wird im
   Command gespeichert und bei Redo nicht neu berechnet.
 - `external-model-object.delete-missing`: nur ausdrücklich bestätigte,
@@ -330,7 +330,13 @@ Kombination aus Originalbytes und Matrix als Entscheidungen bestätigt.
    Diese Row erhält eine stabile ID und `manualQuantity = 0`; ihr historischer
    Gegenbefehl entfernt sie nur, solange Row und Objektlinks vollständig
    unverändert sind. Ein direktes Löschen über diesen internen Gegenbefehl ist
-   als Nutzeraktion gesperrt. Der neue Circuit folgt separat.
+   als Nutzeraktion gesperrt. `external-object.assign-to-new-circuit` schließt
+   den dritten Zielpfad: Ein serverseitig vorgeplanter Circuit mit festem BMK,
+   Standardschutz und genau einer externen Row wird gemeinsam mit den
+   Objektlinks eingefügt. Seine Historiengegenrichtung prüft den vollständigen
+   Circuit-Snapshot und die exakte Linkmenge, bevor sie den Teilbaum entfernt.
+   BMK und UUIDs bleiben bei Redo unverändert. Damit ist die persistente
+   Command-Grundlage dieses Schritts abgeschlossen; API-Planung und UI folgen.
 3. Verteilungsbezogenen Drawer, Filter und Vorschau der Mengenwirkung ergänzen.
 4. Einzel- und Mehrfach-Drag-and-drop samt Warnungen, Undo/Redo und Reload
    testen.
diff --git a/src/db/repositories/external-object-assignment.persistence.ts b/src/db/repositories/external-object-assignment.persistence.ts
new file mode 100644
index 0000000..ddc9891
--- /dev/null
+++ b/src/db/repositories/external-object-assignment.persistence.ts
@@ -0,0 +1,137 @@
+import { and, eq, inArray, isNull } from "drizzle-orm";
+import type { CircuitDeviceRowSnapshot } from "../../domain/models/circuit-device-row-structure-project-command.model.js";
+import type { ExternalModelObjectSnapshot } from "../../external-model/domain/external-model-contracts.js";
+import type { CircuitGroupCategory } from "../../shared/constants/circuit-group.js";
+import type { AppDatabase } from "../database-context.js";
+import { externalModelObjects } from "../schema/external-model-objects.js";
+import { externalRoomMappings } from "../schema/external-room-mappings.js";
+
+export interface ExternalObjectLinkTransition {
+  expected: ExternalModelObjectSnapshot;
+  target: ExternalModelObjectSnapshot;
+}
+
+export function loadExpectedExternalObjectTransitions(
+  database: AppDatabase,
+  projectId: string,
+  transitions: ExternalObjectLinkTransition[],
+  changedMessage: string
+) {
+  const byId = new Map(
+    transitions.map((transition) => [transition.expected.id, transition])
+  );
+  const current = database.select().from(externalModelObjects)
+    .where(inArray(externalModelObjects.id, [...byId.keys()])).all();
+  if (current.length !== byId.size) {
+    throw new Error("One or more external objects no longer exist.");
+  }
+  for (const object of current) {
+    if (
+      object.projectId !== projectId ||
+      !snapshotsEqual(toExternalObjectSnapshot(object), byId.get(object.id)!.expected)
+    ) {
+      throw new Error(changedMessage);
+    }
+  }
+  return transitions;
+}
+
+export function assertExternalObjectsCompatibleWithRow(input: {
+  database: AppDatabase;
+  projectId: string;
+  row: CircuitDeviceRowSnapshot;
+  distributionBoardId: string;
+  category: CircuitGroupCategory;
+  assignedObjects: ExternalModelObjectSnapshot[];
+  allLinkedObjects: ExternalModelObjectSnapshot[];
+  confirmedConflictObjectIds: ReadonlySet<string>;
+}) {
+  const mappings = input.database.select().from(externalRoomMappings)
+    .where(eq(externalRoomMappings.projectId, input.projectId)).all();
+  const roomIdByMappingId = new Map(mappings.map((mapping) => [mapping.id, mapping.roomId]));
+  const markers = new Set(
+    input.allLinkedObjects.map((object) =>
+      object.acceptedSourceValues.selectionMarker.trim()
+    )
+  );
+  if (markers.size > 1) {
+    throw new Error("External objects with different selection markers require separate rows.");
+  }
+  for (const object of input.assignedObjects) {
+    if (object.distributionBoardId !== input.distributionBoardId) {
+      throw new Error("External object distribution does not match target circuit.");
+    }
+    if (object.planningValues.category !== input.category) {
+      throw new Error("External object category does not match target circuit group.");
+    }
+    const roomId = object.externalRoomMappingId === null
+      ? null
+      : roomIdByMappingId.get(object.externalRoomMappingId) ?? null;
+    if (roomId !== input.row.roomId) {
+      throw new Error("External object room does not match target device row.");
+    }
+    if (
+      !matchesRowPlanningValues(input.row, object) &&
+      !input.confirmedConflictObjectIds.has(object.id)
+    ) {
+      throw new Error("External object planning values require explicit conflict confirmation.");
+    }
+  }
+}
+
+export function applyExternalObjectLinks(
+  database: AppDatabase,
+  transitions: ExternalObjectLinkTransition[],
+  changedMessage: string
+) {
+  for (const { expected, target } of transitions) {
+    const updated = database.update(externalModelObjects)
+      .set({ circuitDeviceRowId: target.circuitDeviceRowId })
+      .where(and(
+        eq(externalModelObjects.id, expected.id),
+        expected.circuitDeviceRowId === null
+          ? isNull(externalModelObjects.circuitDeviceRowId)
+          : eq(externalModelObjects.circuitDeviceRowId, expected.circuitDeviceRowId)
+      )).run();
+    if (updated.changes !== 1) throw new Error(changedMessage);
+  }
+}
+
+export function toExternalObjectSnapshot(
+  object: typeof externalModelObjects.$inferSelect
+): ExternalModelObjectSnapshot {
+  return { ...object };
+}
+
+export function snapshotsEqual(left: unknown, right: unknown) {
+  return canonicalJson(left) === canonicalJson(right);
+}
+
+function matchesRowPlanningValues(
+  row: CircuitDeviceRowSnapshot,
+  object: ExternalModelObjectSnapshot
+) {
+  const planning = object.planningValues;
+  return (
+    row.displayName === (planning.displayName ?? row.displayName) &&
+    row.linkedProjectDeviceId === object.linkedProjectDeviceId &&
+    row.category === planning.category &&
+    row.connectionKind === planning.connectionKind &&
+    (planning.powerPerUnitW === null || row.powerPerUnit === planning.powerPerUnitW / 1000) &&
+    row.simultaneityFactor === planning.simultaneityFactor &&
+    row.cosPhi === planning.cosPhi &&
+    row.costGroup === planning.costGroup &&
+    row.remark === planning.remark
+  );
+}
+
+function canonicalJson(value: unknown): string {
+  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
+  if (value !== null && typeof value === "object") {
+    const record = value as Record<string, unknown>;
+    return `{${Object.keys(record).sort().map((key) =>
+      `${JSON.stringify(key)}:${canonicalJson(record[key])}`
+    ).join(",")}}`;
+  }
+  return JSON.stringify(value);
+}
diff --git a/src/db/repositories/external-object-new-circuit-project-command.repository.ts b/src/db/repositories/external-object-new-circuit-project-command.repository.ts
new file mode 100644
index 0000000..c25ac76
--- /dev/null
+++ b/src/db/repositories/external-object-new-circuit-project-command.repository.ts
@@ -0,0 +1,239 @@
+import { and, asc, eq } from "drizzle-orm";
+import { assertCircuitDeviceRowQuantity } from "../../domain/calculations/circuit-device-row-quantity.js";
+import {
+  assertExternalObjectNewCircuitProjectCommand,
+  externalObjectAssignToNewCircuitCommandType,
+  externalObjectDeleteCreatedCircuitCommandType,
+  invertExternalObjectNewCircuitProjectCommand,
+  type ExternalObjectNewCircuitProjectCommand,
+} from "../../domain/models/external-object-new-circuit-project-command.model.js";
+import type { CircuitDeviceRowSnapshot } from "../../domain/models/circuit-device-row-structure-project-command.model.js";
+import type { CircuitSnapshot } from "../../domain/models/circuit-structure-project-command.model.js";
+import type { ExternalObjectNewCircuitProjectCommandStore } from "../../domain/ports/external-object-new-circuit-project-command.store.js";
+import { parseGroupedEquipmentIdentifier } from "../../domain/services/circuit-group-numbering.js";
+import { isElectricalPhaseType } from "../../domain/services/project-voltage.service.js";
+import type { AppDatabase } from "../database-context.js";
+import { circuitDeviceRows } from "../schema/circuit-device-rows.js";
+import { circuitLists } from "../schema/circuit-lists.js";
+import { circuitProtectionDevices } from "../schema/circuit-protection-devices.js";
+import { circuitSections } from "../schema/circuit-sections.js";
+import { circuits } from "../schema/circuits.js";
+import { externalModelObjects } from "../schema/external-model-objects.js";
+import {
+  assertCircuitDeviceRowReferencesInProject,
+  toCircuitDeviceRowInsertValues,
+  toCircuitDeviceRowSnapshot,
+} from "./circuit-device-row-structure.persistence.js";
+import { executeProjectCommandTransaction } from "./project-command-transaction.persistence.js";
+import { resolveCircuitVoltage } from "./project-voltage.persistence.js";
+import {
+  applyExternalObjectLinks,
+  assertExternalObjectsCompatibleWithRow,
+  loadExpectedExternalObjectTransitions,
+  snapshotsEqual,
+} from "./external-object-assignment.persistence.js";
+
+export class ExternalObjectNewCircuitProjectCommandRepository
+  implements ExternalObjectNewCircuitProjectCommandStore
+{
+  constructor(private readonly database: AppDatabase) {}
+
+  execute(input: Parameters<ExternalObjectNewCircuitProjectCommandStore["execute"]>[0]) {
+    assertExternalObjectNewCircuitProjectCommand(input.command);
+    if (
+      input.source === "user" &&
+      input.command.type === externalObjectDeleteCreatedCircuitCommandType
+    ) {
+      throw new Error("Created external circuits may only be removed through project history.");
+    }
+    return executeProjectCommandTransaction(this.database, input, (tx) => {
+      if (input.command.type === externalObjectAssignToNewCircuitCommandType) {
+        this.insert(tx, input.projectId, input.command);
+      } else {
+        this.remove(tx, input.projectId, input.command);
+      }
+      return invertExternalObjectNewCircuitProjectCommand(input.command);
+    });
+  }
+
+  private insert(
+    database: AppDatabase,
+    projectId: string,
+    command: ExternalObjectNewCircuitProjectCommand
+  ) {
+    const circuit = command.payload.circuit;
+    const row = circuit.deviceRows[0]!;
+    const context = this.loadSectionContext(
+      database,
+      projectId,
+      circuit.circuitListId,
+      circuit.sectionId
+    );
+    const parsedIdentifier = parseGroupedEquipmentIdentifier(circuit.equipmentIdentifier);
+    if (
+      !parsedIdentifier ||
+      parsedIdentifier.kind !== "circuit" ||
+      parsedIdentifier.category !== context.category ||
+      parsedIdentifier.groupNumber !== context.groupNumber
+    ) {
+      throw new Error("External circuit equipment identifier does not match target group.");
+    }
+    if (row.category !== context.category || !isElectricalPhaseType(row.phaseType)) {
+      throw new Error("External device row does not match target circuit group.");
+    }
+    assertCircuitDeviceRowReferencesInProject(database, projectId, row);
+    const voltage = resolveCircuitVoltage(database, projectId, circuit.sectionId, [row.phaseType]);
+    if (circuit.voltage !== voltage) {
+      throw new Error("External circuit voltage must match the project phase voltage.");
+    }
+    if (database.select({ id: circuits.id }).from(circuits)
+      .where(eq(circuits.id, circuit.id)).get()) {
+      throw new Error("External circuit id already exists.");
+    }
+    if (database.select({ id: circuits.id }).from(circuits).where(and(
+      eq(circuits.circuitListId, circuit.circuitListId),
+      eq(circuits.equipmentIdentifier, circuit.equipmentIdentifier)
+    )).get()) {
+      throw new Error("Duplicate equipmentIdentifier in circuit list.");
+    }
+    if (database.select({ id: circuitDeviceRows.id }).from(circuitDeviceRows)
+      .where(eq(circuitDeviceRows.id, row.id)).get()) {
+      throw new Error("External device-row id already exists.");
+    }
+
+    const objects = this.loadExpectedObjects(database, projectId, command);
+    assertExternalObjectsCompatibleWithRow({
+      database,
+      projectId,
+      row,
+      distributionBoardId: context.distributionBoardId,
+      category: context.category,
+      assignedObjects: objects.map(({ target }) => target),
+      allLinkedObjects: objects.map(({ target }) => target),
+      confirmedConflictObjectIds: new Set(command.payload.confirmedConflictObjectIds),
+    });
+    assertCircuitDeviceRowQuantity({
+      quantity: row.quantity,
+      manualQuantity: 0,
+      externalObjects: objects.map(({ target }) => ({
+        effectiveQuantity: target.planningValues.effectiveQuantity,
+      })),
+    });
+
+    database.insert(circuits).values(toCircuitValues(circuit)).run();
+    database.insert(circuitDeviceRows).values(toCircuitDeviceRowInsertValues(row)).run();
+    database.insert(circuitProtectionDevices).values(circuit.protectionDevice!).run();
+    applyExternalObjectLinks(
+      database,
+      objects,
+      "External object changed during new-circuit assignment."
+    );
+  }
+
+  private remove(
+    database: AppDatabase,
+    projectId: string,
+    command: ExternalObjectNewCircuitProjectCommand
+  ) {
+    const expectedCircuit = command.payload.circuit;
+    this.loadSectionContext(
+      database,
+      projectId,
+      expectedCircuit.circuitListId,
+      expectedCircuit.sectionId
+    );
+    const current = this.loadCircuitSnapshot(database, expectedCircuit.id);
+    if (!current || !snapshotsEqual(current, expectedCircuit)) {
+      throw new Error("Created external circuit changed before history removal.");
+    }
+    const objects = this.loadExpectedObjects(database, projectId, command);
+    const rowId = expectedCircuit.deviceRows[0]!.id;
+    const linkedObjects = database.select({ id: externalModelObjects.id })
+      .from(externalModelObjects)
+      .where(eq(externalModelObjects.circuitDeviceRowId, rowId)).all();
+    if (
+      linkedObjects.length !== objects.length ||
+      linkedObjects.some(({ id }) => !objects.some(({ expected }) => expected.id === id))
+    ) {
+      throw new Error("Created external circuit has different object links.");
+    }
+    applyExternalObjectLinks(
+      database,
+      objects,
+      "External object changed during new-circuit assignment."
+    );
+    const deleted = database.delete(circuits).where(and(
+      eq(circuits.id, expectedCircuit.id),
+      eq(circuits.circuitListId, expectedCircuit.circuitListId)
+    )).run();
+    if (deleted.changes !== 1) {
+      throw new Error("Created external circuit changed during history removal.");
+    }
+  }
+
+  private loadSectionContext(
+    database: AppDatabase,
+    projectId: string,
+    circuitListId: string,
+    sectionId: string
+  ) {
+    const context = database.select({
+      projectId: circuitLists.projectId,
+      distributionBoardId: circuitLists.distributionBoardId,
+      category: circuitSections.category,
+      groupNumber: circuitSections.groupNumber,
+    }).from(circuitSections)
+      .innerJoin(circuitLists, eq(circuitLists.id, circuitSections.circuitListId))
+      .where(and(
+        eq(circuitSections.id, sectionId),
+        eq(circuitSections.circuitListId, circuitListId)
+      )).get();
+    if (
+      !context ||
+      context.projectId !== projectId ||
+      context.category === null ||
+      context.groupNumber === null
+    ) {
+      throw new Error("Target circuit group does not belong to the project.");
+    }
+    return {
+      distributionBoardId: context.distributionBoardId,
+      category: context.category,
+      groupNumber: context.groupNumber,
+    };
+  }
+
+  private loadExpectedObjects(
+    database: AppDatabase,
+    projectId: string,
+    command: ExternalObjectNewCircuitProjectCommand
+  ) {
+    return loadExpectedExternalObjectTransitions(
+      database,
+      projectId,
+      command.payload.objects,
+      "External object changed before new-circuit assignment."
+    );
+  }
+
+  private loadCircuitSnapshot(database: AppDatabase, circuitId: string): CircuitSnapshot | null {
+    const circuit = database.select().from(circuits).where(eq(circuits.id, circuitId)).get();
+    if (!circuit) return null;
+    const rows = database.select().from(circuitDeviceRows)
+      .where(eq(circuitDeviceRows.circuitId, circuitId))
+      .orderBy(asc(circuitDeviceRows.sortOrder), asc(circuitDeviceRows.id)).all();
+    const protection = database.select().from(circuitProtectionDevices)
+      .where(eq(circuitProtectionDevices.circuitId, circuitId)).get();
+    return {
+      ...circuit,
+      isReserve: Boolean(circuit.isReserve),
+      deviceRows: rows.map(toCircuitDeviceRowSnapshot),
+      protectionDevice: protection ?? null,
+    };
+  }
+}
+
+function toCircuitValues(circuit: CircuitSnapshot) {
+  const { deviceRows: _deviceRows, protectionDevice: _protectionDevice, ...values } = circuit;
+  return { ...values, isReserve: circuit.isReserve ? 1 : 0 };
+}
diff --git a/src/db/repositories/external-object-new-row-project-command.repository.ts b/src/db/repositories/external-object-new-row-project-command.repository.ts
index d2db69c..27146b8 100644
--- a/src/db/repositories/external-object-new-row-project-command.repository.ts
+++ b/src/db/repositories/external-object-new-row-project-command.repository.ts
@@ -1,4 +1,4 @@
-import { and, eq, inArray, isNull } from "drizzle-orm";
+import { eq } from "drizzle-orm";
 import { assertCircuitDeviceRowQuantity } from "../../domain/calculations/circuit-device-row-quantity.js";
 import {
   assertExternalObjectNewRowProjectCommand,
@@ -7,17 +7,14 @@ import {
   invertExternalObjectNewRowProjectCommand,
   type ExternalObjectNewRowProjectCommand,
 } from "../../domain/models/external-object-new-row-project-command.model.js";
-import type { CircuitDeviceRowSnapshot } from "../../domain/models/circuit-device-row-structure-project-command.model.js";
 import type { ExternalObjectNewRowProjectCommandStore } from "../../domain/ports/external-object-new-row-project-command.store.js";
 import { isElectricalPhaseType } from "../../domain/services/project-voltage.service.js";
-import type { ExternalModelObjectSnapshot } from "../../external-model/domain/external-model-contracts.js";
 import type { AppDatabase } from "../database-context.js";
 import { circuitDeviceRows } from "../schema/circuit-device-rows.js";
 import { circuitLists } from "../schema/circuit-lists.js";
 import { circuitSections } from "../schema/circuit-sections.js";
 import { circuits } from "../schema/circuits.js";
 import { externalModelObjects } from "../schema/external-model-objects.js";
-import { externalRoomMappings } from "../schema/external-room-mappings.js";
 import {
   assertCircuitDeviceRowReferencesInProject,
   toCircuitDeviceRowInsertValues,
@@ -25,6 +22,12 @@ import {
 } from "./circuit-device-row-structure.persistence.js";
 import { executeProjectCommandTransaction } from "./project-command-transaction.persistence.js";
 import { updateDerivedCircuitVoltage } from "./project-voltage.persistence.js";
+import {
+  applyExternalObjectLinks,
+  assertExternalObjectsCompatibleWithRow,
+  loadExpectedExternalObjectTransitions,
+  snapshotsEqual,
+} from "./external-object-assignment.persistence.js";
 
 export class ExternalObjectNewRowProjectCommandRepository
   implements ExternalObjectNewRowProjectCommandStore
@@ -68,14 +71,16 @@ export class ExternalObjectNewRowProjectCommandRepository
       throw new Error("External device-row id already exists.");
     }
     const objects = this.loadExpectedObjects(database, projectId, command);
-    this.assertTargetCompatibility(
+    assertExternalObjectsCompatibleWithRow({
       database,
+      projectId,
       row,
-      context.distributionBoardId,
-      context.category,
-      objects.map((object) => object.target),
-      new Set(command.payload.confirmedConflictObjectIds)
-    );
+      distributionBoardId: context.distributionBoardId,
+      category: context.category,
+      assignedObjects: objects.map(({ target }) => target),
+      allLinkedObjects: objects.map(({ target }) => target),
+      confirmedConflictObjectIds: new Set(command.payload.confirmedConflictObjectIds),
+    });
     assertCircuitDeviceRowQuantity({
       quantity: row.quantity,
       manualQuantity: 0,
@@ -86,7 +91,11 @@ export class ExternalObjectNewRowProjectCommandRepository
 
     database.insert(circuitDeviceRows).values(toCircuitDeviceRowInsertValues(row)).run();
     this.updateCircuitState(database, projectId, row.circuitId);
-    this.applyObjectLinks(database, objects);
+    applyExternalObjectLinks(
+      database,
+      objects,
+      "External object changed during new-row assignment."
+    );
   }
 
   private remove(
@@ -98,7 +107,7 @@ export class ExternalObjectNewRowProjectCommandRepository
     this.loadCircuitContext(database, projectId, expectedRow.circuitId);
     const currentRow = database.select().from(circuitDeviceRows)
       .where(eq(circuitDeviceRows.id, expectedRow.id)).get();
-    if (!currentRow || !same(toCircuitDeviceRowSnapshot(currentRow), expectedRow)) {
+    if (!currentRow || !snapshotsEqual(toCircuitDeviceRowSnapshot(currentRow), expectedRow)) {
       throw new Error("Created external device row changed before history removal.");
     }
     const objects = this.loadExpectedObjects(database, projectId, command);
@@ -111,7 +120,11 @@ export class ExternalObjectNewRowProjectCommandRepository
     ) {
       throw new Error("Created external device row has different object links.");
     }
-    this.applyObjectLinks(database, objects);
+    applyExternalObjectLinks(
+      database,
+      objects,
+      "External object changed during new-row assignment."
+    );
     const deleted = database.delete(circuitDeviceRows)
       .where(eq(circuitDeviceRows.id, expectedRow.id)).run();
     if (deleted.changes !== 1) {
@@ -144,76 +157,12 @@ export class ExternalObjectNewRowProjectCommandRepository
     projectId: string,
     command: ExternalObjectNewRowProjectCommand
   ) {
-    const transitions = new Map(
-      command.payload.objects.map((transition) => [transition.expected.id, transition])
+    return loadExpectedExternalObjectTransitions(
+      database,
+      projectId,
+      command.payload.objects,
+      "External object changed before new-row assignment."
     );
-    const current = database.select().from(externalModelObjects)
-      .where(inArray(externalModelObjects.id, [...transitions.keys()])).all();
-    if (current.length !== transitions.size) {
-      throw new Error("One or more external objects no longer exist.");
-    }
-    for (const object of current) {
-      const expected = transitions.get(object.id)!.expected;
-      if (object.projectId !== projectId || !same(toExternalObjectSnapshot(object), expected)) {
-        throw new Error("External object changed before new-row assignment.");
-      }
-    }
-    return command.payload.objects;
-  }
-
-  private assertTargetCompatibility(
-    database: AppDatabase,
-    row: CircuitDeviceRowSnapshot,
-    distributionBoardId: string,
-    category: string,
-    objects: ExternalModelObjectSnapshot[],
-    confirmedConflicts: Set<string>
-  ) {
-    const roomMappings = database.select().from(externalRoomMappings)
-      .where(eq(externalRoomMappings.projectId, objects[0]!.projectId)).all();
-    const roomIdByMappingId = new Map(roomMappings.map((mapping) => [mapping.id, mapping.roomId]));
-    const selectionMarkers = new Set(
-      objects.map((object) => object.acceptedSourceValues.selectionMarker.trim())
-    );
-    if (selectionMarkers.size > 1) {
-      throw new Error("External objects with different selection markers require separate rows.");
-    }
-    for (const object of objects) {
-      if (object.distributionBoardId !== distributionBoardId) {
-        throw new Error("External object distribution does not match target circuit.");
-      }
-      if (object.planningValues.category !== category) {
-        throw new Error("External object category does not match target circuit group.");
-      }
-      const objectRoomId = object.externalRoomMappingId === null
-        ? null
-        : roomIdByMappingId.get(object.externalRoomMappingId) ?? null;
-      if (objectRoomId !== row.roomId) {
-        throw new Error("External object room does not match the new device row.");
-      }
-      if (!matchesRowPlanningValues(row, object) && !confirmedConflicts.has(object.id)) {
-        throw new Error("External object planning values require explicit conflict confirmation.");
-      }
-    }
-  }
-
-  private applyObjectLinks(
-    database: AppDatabase,
-    objects: ExternalObjectNewRowProjectCommand["payload"]["objects"]
-  ) {
-    for (const { expected, target } of objects) {
-      const result = database.update(externalModelObjects)
-        .set({ circuitDeviceRowId: target.circuitDeviceRowId })
-        .where(and(
-          eq(externalModelObjects.id, expected.id),
-          expected.circuitDeviceRowId === null
-            ? isNull(externalModelObjects.circuitDeviceRowId)
-            : eq(externalModelObjects.circuitDeviceRowId, expected.circuitDeviceRowId)
-        )).run();
-      if (result.changes !== 1) {
-        throw new Error("External object changed during new-row assignment.");
-      }
-    }
   }
 
   private updateCircuitState(database: AppDatabase, projectId: string, circuitId: string) {
@@ -225,42 +174,3 @@ export class ExternalObjectNewRowProjectCommandRepository
     updateDerivedCircuitVoltage(database, projectId, circuitId);
   }
 }
-
-function matchesRowPlanningValues(
-  row: CircuitDeviceRowSnapshot,
-  object: ExternalModelObjectSnapshot
-) {
-  const planning = object.planningValues;
-  return (
-    row.displayName === (planning.displayName ?? row.displayName) &&
-    row.linkedProjectDeviceId === object.linkedProjectDeviceId &&
-    row.category === planning.category &&
-    row.connectionKind === planning.connectionKind &&
-    (planning.powerPerUnitW === null || row.powerPerUnit === planning.powerPerUnitW / 1000) &&
-    row.simultaneityFactor === planning.simultaneityFactor &&
-    row.cosPhi === planning.cosPhi &&
-    row.costGroup === planning.costGroup &&
-    row.remark === planning.remark
-  );
-}
-
-function toExternalObjectSnapshot(
-  object: typeof externalModelObjects.$inferSelect
-): ExternalModelObjectSnapshot {
-  return { ...object };
-}
-
-function same(left: unknown, right: unknown) {
-  return canonicalJson(left) === canonicalJson(right);
-}
-
-function canonicalJson(value: unknown): string {
-  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
-  if (value !== null && typeof value === "object") {
-    const record = value as Record<string, unknown>;
-    return `{${Object.keys(record).sort().map((key) =>
-      `${JSON.stringify(key)}:${canonicalJson(record[key])}`
-    ).join(",")}}`;
-  }
-  return JSON.stringify(value);
-}
diff --git a/src/db/repositories/external-object-row-assignment-project-command.repository.ts b/src/db/repositories/external-object-row-assignment-project-command.repository.ts
index dcf33b1..b6e8123 100644
--- a/src/db/repositories/external-object-row-assignment-project-command.repository.ts
+++ b/src/db/repositories/external-object-row-assignment-project-command.repository.ts
@@ -6,18 +6,22 @@ import {
   assertExternalObjectRowAssignmentProjectCommand,
   invertExternalObjectRowAssignmentProjectCommand,
 } from "../../domain/models/external-object-row-assignment-project-command.model.js";
-import type { CircuitDeviceRowSnapshot } from "../../domain/models/circuit-device-row-structure-project-command.model.js";
 import type { ExternalObjectRowAssignmentProjectCommandStore } from "../../domain/ports/external-object-row-assignment-project-command.store.js";
-import type { ExternalModelObjectSnapshot } from "../../external-model/domain/external-model-contracts.js";
 import type { AppDatabase } from "../database-context.js";
 import { circuitDeviceRows } from "../schema/circuit-device-rows.js";
 import { circuitLists } from "../schema/circuit-lists.js";
 import { circuitSections } from "../schema/circuit-sections.js";
 import { circuits } from "../schema/circuits.js";
 import { externalModelObjects } from "../schema/external-model-objects.js";
-import { externalRoomMappings } from "../schema/external-room-mappings.js";
 import { toCircuitDeviceRowSnapshot } from "./circuit-device-row-structure.persistence.js";
 import { executeProjectCommandTransaction } from "./project-command-transaction.persistence.js";
+import {
+  applyExternalObjectLinks,
+  assertExternalObjectsCompatibleWithRow,
+  loadExpectedExternalObjectTransitions,
+  snapshotsEqual,
+  toExternalObjectSnapshot,
+} from "./external-object-assignment.persistence.js";
 
 export class ExternalObjectRowAssignmentProjectCommandRepository
   implements ExternalObjectRowAssignmentProjectCommandStore
@@ -44,29 +48,23 @@ export class ExternalObjectRowAssignmentProjectCommandRepository
       command.payload.objects.map((transition) => [transition.expected.id, transition])
     );
     const rowIds = [...rowTransitions.keys()];
-    const objectIds = [...objectTransitions.keys()];
     const currentRows = database.select().from(circuitDeviceRows)
       .where(inArray(circuitDeviceRows.id, rowIds)).all();
-    const currentObjects = database.select().from(externalModelObjects)
-      .where(inArray(externalModelObjects.id, objectIds)).all();
-    if (currentRows.length !== rowIds.length || currentObjects.length !== objectIds.length) {
+    if (currentRows.length !== rowIds.length) {
       throw new Error("External object assignment target no longer exists.");
     }
     for (const row of currentRows) {
       const expected = rowTransitions.get(row.id)!.expected;
-      if (!same(toCircuitDeviceRowSnapshot(row), expected)) {
+      if (!snapshotsEqual(toCircuitDeviceRowSnapshot(row), expected)) {
         throw new Error("Circuit device row changed before external object assignment.");
       }
     }
-    for (const object of currentObjects) {
-      const expected = objectTransitions.get(object.id)!.expected;
-      if (!same(toExternalObjectSnapshot(object), expected)) {
-        throw new Error("External object changed before row assignment.");
-      }
-      if (object.projectId !== projectId) {
-        throw new Error("External object belongs to another project.");
-      }
-    }
+    loadExpectedExternalObjectTransitions(
+      database,
+      projectId,
+      command.payload.objects,
+      "External object changed before row assignment."
+    );
 
     const rowContexts = database
       .select({
@@ -83,7 +81,9 @@ export class ExternalObjectRowAssignmentProjectCommandRepository
       .all();
     if (
       rowContexts.length !== rowIds.length ||
-      rowContexts.some((context) => context.projectId !== projectId)
+      rowContexts.some((context) =>
+        context.projectId !== projectId || context.category === null
+      )
     ) {
       throw new Error("Circuit device row belongs to another project.");
     }
@@ -95,47 +95,26 @@ export class ExternalObjectRowAssignmentProjectCommandRepository
     const targetObjects = allProjectObjects.map((object) =>
       objectTransitions.get(object.id)?.target ?? object
     );
-    const mappings = database.select().from(externalRoomMappings)
-      .where(eq(externalRoomMappings.projectId, projectId)).all();
-    const roomIdByMappingId = new Map(mappings.map((mapping) => [mapping.id, mapping.roomId]));
     const confirmedConflicts = new Set(command.payload.confirmedConflictObjectIds);
 
-    for (const transition of command.payload.objects) {
-      const object = transition.target;
-      if (object.circuitDeviceRowId === null) continue;
-      const row = rowTransitions.get(object.circuitDeviceRowId)?.target;
-      const context = contextByRowId.get(object.circuitDeviceRowId);
-      if (!row || !context) throw new Error("External object target row is incomplete.");
-      if (
-        object.distributionBoardId === null ||
-        object.distributionBoardId !== context.distributionBoardId
-      ) {
-        throw new Error("External object distribution does not match target row.");
-      }
-      if (object.planningValues.category !== context.category) {
-        throw new Error("External object category does not match target circuit group.");
-      }
-      const objectRoomId = object.externalRoomMappingId === null
-        ? null
-        : roomIdByMappingId.get(object.externalRoomMappingId) ?? null;
-      if (objectRoomId !== row.roomId) {
-        throw new Error("External object room does not match target row.");
-      }
-      if (!matchesRowPlanningValues(row, object) && !confirmedConflicts.has(object.id)) {
-        throw new Error("External object planning values require explicit conflict confirmation.");
-      }
-    }
-
     for (const transition of command.payload.rows) {
       const linkedObjects = targetObjects.filter(
         (object) => object.circuitDeviceRowId === transition.target.id
       );
-      const selectionMarkers = new Set(
-        linkedObjects.map((object) => object.acceptedSourceValues.selectionMarker.trim())
-      );
-      if (selectionMarkers.size > 1) {
-        throw new Error("External objects with different selection markers require separate rows.");
-      }
+      const assignedObjects = command.payload.objects
+        .map(({ target }) => target)
+        .filter((object) => object.circuitDeviceRowId === transition.target.id);
+      const context = contextByRowId.get(transition.target.id)!;
+      assertExternalObjectsCompatibleWithRow({
+        database,
+        projectId,
+        row: transition.target,
+        distributionBoardId: context.distributionBoardId,
+        category: context.category!,
+        assignedObjects,
+        allLinkedObjects: linkedObjects,
+        confirmedConflictObjectIds: confirmedConflicts,
+      });
       assertCircuitDeviceRowQuantity({
         quantity: transition.target.quantity,
         manualQuantity: transition.target.manualQuantity ?? transition.target.quantity,
@@ -155,50 +134,10 @@ export class ExternalObjectRowAssignmentProjectCommandRepository
         )).run();
       if (result.changes !== 1) throw new Error("Circuit device row changed during assignment.");
     }
-    for (const transition of command.payload.objects) {
-      const result = database.update(externalModelObjects)
-        .set({ circuitDeviceRowId: transition.target.circuitDeviceRowId })
-        .where(eq(externalModelObjects.id, transition.expected.id)).run();
-      if (result.changes !== 1) throw new Error("External object changed during assignment.");
-    }
+    applyExternalObjectLinks(
+      database,
+      command.payload.objects,
+      "External object changed during assignment."
+    );
   }
 }
-
-function matchesRowPlanningValues(
-  row: CircuitDeviceRowSnapshot,
-  object: ExternalModelObjectSnapshot
-) {
-  const planning = object.planningValues;
-  return (
-    row.displayName === (planning.displayName ?? row.displayName) &&
-    row.linkedProjectDeviceId === object.linkedProjectDeviceId &&
-    row.category === planning.category &&
-    row.connectionKind === planning.connectionKind &&
-    (planning.powerPerUnitW === null || row.powerPerUnit === planning.powerPerUnitW / 1000) &&
-    row.simultaneityFactor === planning.simultaneityFactor &&
-    row.cosPhi === planning.cosPhi &&
-    row.costGroup === planning.costGroup &&
-    row.remark === planning.remark
-  );
-}
-
-function toExternalObjectSnapshot(
-  object: typeof externalModelObjects.$inferSelect
-): ExternalModelObjectSnapshot {
-  return { ...object };
-}
-
-function same(left: unknown, right: unknown) {
-  return canonicalJson(left) === canonicalJson(right);
-}
-
-function canonicalJson(value: unknown): string {
-  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
-  if (value !== null && typeof value === "object") {
-    const record = value as Record<string, unknown>;
-    return `{${Object.keys(record).sort().map((key) =>
-      `${JSON.stringify(key)}:${canonicalJson(record[key])}`
-    ).join(",")}}`;
-  }
-  return JSON.stringify(value);
-}
diff --git a/src/domain/models/external-object-new-circuit-project-command.model.ts b/src/domain/models/external-object-new-circuit-project-command.model.ts
new file mode 100644
index 0000000..b34a449
--- /dev/null
+++ b/src/domain/models/external-object-new-circuit-project-command.model.ts
@@ -0,0 +1,168 @@
+import type { ExternalModelObjectSnapshot } from "../../external-model/domain/external-model-contracts.js";
+import {
+  assertCircuitInsertProjectCommand,
+  circuitInsertCommandType,
+  circuitStructureCommandSchemaVersion,
+  type CircuitSnapshot,
+} from "./circuit-structure-project-command.model.js";
+import type { SerializedProjectCommand } from "./project-command.model.js";
+import { parseExternalModelStateSnapshot } from "./project-state-snapshot.model.js";
+
+export const externalObjectAssignToNewCircuitCommandType =
+  "external-object.assign-to-new-circuit" as const;
+export const externalObjectDeleteCreatedCircuitCommandType =
+  "external-object.unassign-and-delete-created-circuit" as const;
+export const externalObjectNewCircuitCommandSchemaVersion = 1 as const;
+
+export interface ExternalObjectNewCircuitPayload {
+  circuit: CircuitSnapshot;
+  objects: Array<{
+    expected: ExternalModelObjectSnapshot;
+    target: ExternalModelObjectSnapshot;
+  }>;
+  confirmedConflictObjectIds: string[];
+}
+
+export interface ExternalObjectNewCircuitProjectCommand
+  extends SerializedProjectCommand<ExternalObjectNewCircuitPayload> {
+  schemaVersion: typeof externalObjectNewCircuitCommandSchemaVersion;
+  type:
+    | typeof externalObjectAssignToNewCircuitCommandType
+    | typeof externalObjectDeleteCreatedCircuitCommandType;
+}
+
+export function createExternalObjectNewCircuitProjectCommand(
+  type: ExternalObjectNewCircuitProjectCommand["type"],
+  payload: ExternalObjectNewCircuitPayload
+): ExternalObjectNewCircuitProjectCommand {
+  const row = payload.circuit.deviceRows[0];
+  const command: ExternalObjectNewCircuitProjectCommand = {
+    schemaVersion: externalObjectNewCircuitCommandSchemaVersion,
+    type,
+    payload: {
+      circuit: row
+        ? {
+            ...payload.circuit,
+            deviceRows: [{
+              ...row,
+              manualQuantity: row.manualQuantity ?? row.quantity,
+            }],
+          }
+        : payload.circuit,
+      objects: payload.objects,
+      confirmedConflictObjectIds: [...payload.confirmedConflictObjectIds],
+    },
+  };
+  assertExternalObjectNewCircuitProjectCommand(command);
+  return command;
+}
+
+export function invertExternalObjectNewCircuitProjectCommand(
+  command: ExternalObjectNewCircuitProjectCommand
+) {
+  return createExternalObjectNewCircuitProjectCommand(
+    command.type === externalObjectAssignToNewCircuitCommandType
+      ? externalObjectDeleteCreatedCircuitCommandType
+      : externalObjectAssignToNewCircuitCommandType,
+    {
+      circuit: command.payload.circuit,
+      objects: command.payload.objects.map(({ expected, target }) => ({
+        expected: target,
+        target: expected,
+      })),
+      confirmedConflictObjectIds: command.payload.confirmedConflictObjectIds,
+    }
+  );
+}
+
+export function assertExternalObjectNewCircuitProjectCommand(
+  command: SerializedProjectCommand<unknown>
+): asserts command is ExternalObjectNewCircuitProjectCommand {
+  if (
+    command.schemaVersion !== externalObjectNewCircuitCommandSchemaVersion ||
+    (command.type !== externalObjectAssignToNewCircuitCommandType &&
+      command.type !== externalObjectDeleteCreatedCircuitCommandType) ||
+    !isRecord(command.payload) ||
+    !Array.isArray(command.payload.objects) ||
+    command.payload.objects.length === 0 ||
+    !Array.isArray(command.payload.confirmedConflictObjectIds)
+  ) {
+    throw new Error("Unsupported external object new-circuit command.");
+  }
+  assertCircuitInsertProjectCommand({
+    schemaVersion: circuitStructureCommandSchemaVersion,
+    type: circuitInsertCommandType,
+    payload: { circuit: command.payload.circuit },
+  });
+  const circuit = command.payload.circuit as CircuitSnapshot;
+  if (
+    circuit.deviceRows.length !== 1 ||
+    circuit.deviceRows[0]!.manualQuantity !== 0 ||
+    circuit.protectionDevice === undefined ||
+    circuit.protectionDevice === null
+  ) {
+    throw new Error(
+      "An external circuit must contain one external-only row and protection device."
+    );
+  }
+  const rowId = circuit.deviceRows[0]!.id;
+  const objectIds = new Set<string>();
+  for (const transition of command.payload.objects) {
+    if (!isRecord(transition)) throw new Error("Invalid external object transition.");
+    const expected = parseObject(transition.expected);
+    const target = parseObject(transition.target);
+    if (expected.id !== target.id || objectIds.has(expected.id)) {
+      throw new Error("New-circuit assignment contains mismatched or duplicate objects.");
+    }
+    objectIds.add(expected.id);
+    const assigning = command.type === externalObjectAssignToNewCircuitCommandType;
+    if (
+      (assigning && (expected.circuitDeviceRowId !== null || target.circuitDeviceRowId !== rowId)) ||
+      (!assigning && (expected.circuitDeviceRowId !== rowId || target.circuitDeviceRowId !== null))
+    ) {
+      throw new Error("External object links do not match the new-circuit action.");
+    }
+    assertOnlyAssignmentChanged(expected, target);
+  }
+  const confirmedIds = new Set<string>();
+  for (const objectId of command.payload.confirmedConflictObjectIds) {
+    if (typeof objectId !== "string" || !objectIds.has(objectId) || confirmedIds.has(objectId)) {
+      throw new Error("New-circuit assignment contains an invalid conflict confirmation.");
+    }
+    confirmedIds.add(objectId);
+  }
+}
+
+function parseObject(value: unknown): ExternalModelObjectSnapshot {
+  return parseExternalModelStateSnapshot({
+    source: null,
+    importBatches: [],
+    roomMappings: [],
+    objects: [value],
+  }).objects[0]!;
+}
+
+function assertOnlyAssignmentChanged(
+  expected: ExternalModelObjectSnapshot,
+  target: ExternalModelObjectSnapshot
+) {
+  const expectedRest = { ...expected, circuitDeviceRowId: null };
+  const targetRest = { ...target, circuitDeviceRowId: null };
+  if (canonicalJson(expectedRest) !== canonicalJson(targetRest)) {
+    throw new Error("New-circuit assignment may only change the external object row link.");
+  }
+}
+
+function canonicalJson(value: unknown): string {
+  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
+  if (isRecord(value)) {
+    return `{${Object.keys(value).sort().map((key) =>
+      `${JSON.stringify(key)}:${canonicalJson(value[key])}`
+    ).join(",")}}`;
+  }
+  return JSON.stringify(value);
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return value !== null && typeof value === "object" && !Array.isArray(value);
+}
diff --git a/src/domain/ports/external-object-new-circuit-project-command.store.ts b/src/domain/ports/external-object-new-circuit-project-command.store.ts
new file mode 100644
index 0000000..efd13ba
--- /dev/null
+++ b/src/domain/ports/external-object-new-circuit-project-command.store.ts
@@ -0,0 +1,19 @@
+import type { ExternalObjectNewCircuitProjectCommand } from "../models/external-object-new-circuit-project-command.model.js";
+import type { AppendedProjectRevision, ProjectRevisionSource } from "./project-revision.store.js";
+
+export interface ExecuteExternalObjectNewCircuitCommandInput {
+  projectId: string;
+  expectedRevision: number;
+  source: ProjectRevisionSource;
+  description?: string;
+  actorId?: string;
+  historyTargetChangeSetId?: string;
+  command: ExternalObjectNewCircuitProjectCommand;
+}
+
+export interface ExternalObjectNewCircuitProjectCommandStore {
+  execute(input: ExecuteExternalObjectNewCircuitCommandInput): {
+    revision: AppendedProjectRevision;
+    inverse: ExternalObjectNewCircuitProjectCommand;
+  };
+}
diff --git a/src/domain/services/project-command.service.ts b/src/domain/services/project-command.service.ts
index be66428..bee31a3 100644
--- a/src/domain/services/project-command.service.ts
+++ b/src/domain/services/project-command.service.ts
@@ -182,6 +182,12 @@ import {
   externalObjectDeleteCreatedRowCommandType,
 } from "../models/external-object-new-row-project-command.model.js";
 import type { ExternalObjectNewRowProjectCommandStore } from "../ports/external-object-new-row-project-command.store.js";
+import {
+  assertExternalObjectNewCircuitProjectCommand,
+  externalObjectAssignToNewCircuitCommandType,
+  externalObjectDeleteCreatedCircuitCommandType,
+} from "../models/external-object-new-circuit-project-command.model.js";
+import type { ExternalObjectNewCircuitProjectCommandStore } from "../ports/external-object-new-circuit-project-command.store.js";
 
 interface DispatchProjectCommandInput {
   projectId: string;
@@ -220,7 +226,8 @@ export class ProjectCommandService implements ProjectCommandExecutor {
     private readonly externalCsvConfigurationStore?: ExternalCsvConfigurationProjectCommandStore,
     private readonly externalInitialImportStore?: ExternalInitialImportProjectCommandStore,
     private readonly externalObjectRowAssignmentStore?: ExternalObjectRowAssignmentProjectCommandStore,
-    private readonly externalObjectNewRowStore?: ExternalObjectNewRowProjectCommandStore
+    private readonly externalObjectNewRowStore?: ExternalObjectNewRowProjectCommandStore,
+    private readonly externalObjectNewCircuitStore?: ExternalObjectNewCircuitProjectCommandStore
   ) {}
 
   executeUser(
@@ -618,6 +625,17 @@ export class ProjectCommandService implements ProjectCommandExecutor {
           command: input.command,
         }).revision;
       }
+      case externalObjectAssignToNewCircuitCommandType:
+      case externalObjectDeleteCreatedCircuitCommandType: {
+        assertExternalObjectNewCircuitProjectCommand(input.command);
+        if (!this.externalObjectNewCircuitStore) {
+          throw new Error("External object new-circuit store is not available.");
+        }
+        return this.externalObjectNewCircuitStore.execute({
+          ...input,
+          command: input.command,
+        }).revision;
+      }
       case projectStateRestoreCommandType: {
         assertProjectStateRestoreCommand(input.command);
         return this.projectStateRestoreStore.execute({
diff --git a/src/server/composition/project-command-stores.ts b/src/server/composition/project-command-stores.ts
index 9e63ed6..79a4a9f 100644
--- a/src/server/composition/project-command-stores.ts
+++ b/src/server/composition/project-command-stores.ts
@@ -26,6 +26,7 @@ import { ExternalCsvConfigurationProjectCommandRepository } from "../../db/repos
 import { ExternalInitialImportProjectCommandRepository } from "../../db/repositories/external-initial-import-project-command.repository.js";
 import { ExternalObjectRowAssignmentProjectCommandRepository } from "../../db/repositories/external-object-row-assignment-project-command.repository.js";
 import { ExternalObjectNewRowProjectCommandRepository } from "../../db/repositories/external-object-new-row-project-command.repository.js";
+import { ExternalObjectNewCircuitProjectCommandRepository } from "../../db/repositories/external-object-new-circuit-project-command.repository.js";
 
 export const circuitProjectCommandStore = new CircuitProjectCommandRepository(db);
 export const circuitDeviceRowProjectCommandStore =
@@ -77,6 +78,8 @@ export const externalObjectRowAssignmentProjectCommandStore =
   new ExternalObjectRowAssignmentProjectCommandRepository(db);
 export const externalObjectNewRowProjectCommandStore =
   new ExternalObjectNewRowProjectCommandRepository(db);
+export const externalObjectNewCircuitProjectCommandStore =
+  new ExternalObjectNewCircuitProjectCommandRepository(db);
 export const projectCommandService = new ProjectCommandService(
   circuitProjectCommandStore,
   circuitDeviceRowProjectCommandStore,
@@ -103,5 +106,6 @@ export const projectCommandService = new ProjectCommandService(
   externalCsvConfigurationProjectCommandStore,
   externalInitialImportProjectCommandStore,
   externalObjectRowAssignmentProjectCommandStore,
-  externalObjectNewRowProjectCommandStore
+  externalObjectNewRowProjectCommandStore,
+  externalObjectNewCircuitProjectCommandStore
 );
diff --git a/tests/external-object-row-assignment-project-command.repository.test.ts b/tests/external-object-row-assignment-project-command.repository.test.ts
index 4e127f1..da8551e 100644
--- a/tests/external-object-row-assignment-project-command.repository.test.ts
+++ b/tests/external-object-row-assignment-project-command.repository.test.ts
@@ -6,11 +6,13 @@ import { migrate } from "drizzle-orm/better-sqlite3/migrator";
 import { createDatabaseContext, type AppDatabase } from "../src/db/database-context.js";
 import { ExternalObjectRowAssignmentProjectCommandRepository } from "../src/db/repositories/external-object-row-assignment-project-command.repository.js";
 import { ExternalObjectNewRowProjectCommandRepository } from "../src/db/repositories/external-object-new-row-project-command.repository.js";
+import { ExternalObjectNewCircuitProjectCommandRepository } from "../src/db/repositories/external-object-new-circuit-project-command.repository.js";
 import { toCircuitDeviceRowSnapshot } from "../src/db/repositories/circuit-device-row-structure.persistence.js";
 import { circuitDeviceRows } from "../src/db/schema/circuit-device-rows.js";
 import { circuitLists } from "../src/db/schema/circuit-lists.js";
 import { circuitSections } from "../src/db/schema/circuit-sections.js";
 import { circuits } from "../src/db/schema/circuits.js";
+import { circuitProtectionDevices } from "../src/db/schema/circuit-protection-devices.js";
 import { distributionBoards } from "../src/db/schema/distribution-boards.js";
 import { externalImportBatches } from "../src/db/schema/external-import-batches.js";
 import { externalModelObjects } from "../src/db/schema/external-model-objects.js";
@@ -24,6 +26,10 @@ import {
   createExternalObjectNewRowProjectCommand,
   externalObjectAssignToNewRowCommandType,
 } from "../src/domain/models/external-object-new-row-project-command.model.js";
+import {
+  createExternalObjectNewCircuitProjectCommand,
+  externalObjectAssignToNewCircuitCommandType,
+} from "../src/domain/models/external-object-new-circuit-project-command.model.js";
 import type { ExternalModelObjectSnapshot } from "../src/external-model/domain/external-model-contracts.js";
 import { externalCsvTestConfiguration } from "./fixtures/revit-csv-fixtures.js";
 
@@ -376,3 +382,192 @@ describe("external object new-row project command", () => {
     }
   });
 });
+
+function newExternalCircuit(database: AppDatabase) {
+  const sourceRow = row(database, "row-2");
+  return {
+    id: "circuit-new",
+    circuitListId: "list-1",
+    sectionId: "section-1",
+    equipmentIdentifier: "-2F1.3",
+    displayName: "Steckdose",
+    sortOrder: 30,
+    cableType: null,
+    cableCrossSection: null,
+    cableLength: null,
+    rcdAssignment: null,
+    terminalDesignation: null,
+    voltage: 230,
+    controlRequirement: null,
+    status: null,
+    isReserve: false,
+    remark: null,
+    deviceRows: [{
+      ...sourceRow,
+      id: "row-new",
+      circuitId: "circuit-new",
+      quantity: 2,
+      manualQuantity: 0,
+    }],
+    protectionDevice: {
+      circuitId: "circuit-new",
+      type: "FI_LS" as const,
+      ratedCurrentA: 16,
+      fuseUtilizationCategory: null,
+      tripCharacteristic: "B" as const,
+      rcdType: "A" as const,
+      ratedResidualCurrentMa: 30,
+    },
+  };
+}
+
+describe("external object new-circuit project command", () => {
+  it("creates circuit, protection, row and links as one undoable revision", () => {
+    const context = createFixture(null);
+    try {
+      const object = objectSnapshot(null);
+      const circuit = newExternalCircuit(context.db);
+      const command = createExternalObjectNewCircuitProjectCommand(
+        externalObjectAssignToNewCircuitCommandType,
+        {
+          circuit,
+          objects: [{
+            expected: object,
+            target: { ...object, circuitDeviceRowId: "row-new" },
+          }],
+          confirmedConflictObjectIds: [],
+        }
+      );
+      const repository = new ExternalObjectNewCircuitProjectCommandRepository(context.db);
+      const inserted = repository.execute({
+        projectId: "project-1",
+        expectedRevision: 0,
+        source: "user",
+        command,
+      });
+      assert.equal(
+        context.db.select().from(circuits).where(eq(circuits.id, "circuit-new")).get()!
+          .equipmentIdentifier,
+        "-2F1.3"
+      );
+      assert.equal(row(context.db, "row-new").manualQuantity, 0);
+      assert.equal(
+        context.db.select().from(circuitProtectionDevices)
+          .where(eq(circuitProtectionDevices.circuitId, "circuit-new")).get()!.type,
+        "FI_LS"
+      );
+      assert.equal(
+        context.db.select().from(externalModelObjects).get()!.circuitDeviceRowId,
+        "row-new"
+      );
+      assert.throws(
+        () => repository.execute({
+          projectId: "project-1",
+          expectedRevision: 1,
+          source: "user",
+          command: inserted.inverse,
+        }),
+        /only be removed through project history/
+      );
+
+      const undone = repository.execute({
+        projectId: "project-1",
+        expectedRevision: 1,
+        source: "undo",
+        historyTargetChangeSetId: inserted.revision.changeSetId,
+        command: inserted.inverse,
+      });
+      assert.equal(
+        context.db.select().from(circuits).where(eq(circuits.id, "circuit-new")).get(),
+        undefined
+      );
+      assert.equal(context.db.select().from(externalModelObjects).get()!.circuitDeviceRowId, null);
+
+      repository.execute({
+        projectId: "project-1",
+        expectedRevision: 2,
+        source: "redo",
+        historyTargetChangeSetId: inserted.revision.changeSetId,
+        command: undone.inverse,
+      });
+      assert.equal(
+        context.db.select().from(circuits).where(eq(circuits.id, "circuit-new")).get()!
+          .equipmentIdentifier,
+        "-2F1.3"
+      );
+    } finally {
+      context.close();
+    }
+  });
+
+  it("rejects a preplanned BMK that does not belong to the target group", () => {
+    const context = createFixture(null);
+    try {
+      const object = objectSnapshot(null);
+      const circuit = {
+        ...newExternalCircuit(context.db),
+        equipmentIdentifier: "-1F1.3",
+      };
+      assert.throws(
+        () => new ExternalObjectNewCircuitProjectCommandRepository(context.db).execute({
+          projectId: "project-1",
+          expectedRevision: 0,
+          source: "user",
+          command: createExternalObjectNewCircuitProjectCommand(
+            externalObjectAssignToNewCircuitCommandType,
+            {
+              circuit,
+              objects: [{
+                expected: object,
+                target: { ...object, circuitDeviceRowId: "row-new" },
+              }],
+              confirmedConflictObjectIds: [],
+            }
+          ),
+        }),
+        /equipment identifier does not match target group/
+      );
+      assert.equal(context.db.select().from(externalModelObjects).get()!.circuitDeviceRowId, null);
+    } finally {
+      context.close();
+    }
+  });
+
+  it("rolls back the complete circuit subtree when history persistence fails", () => {
+    const context = createFixture(null);
+    try {
+      context.sqlite.exec(`
+        CREATE TRIGGER fail_new_circuit_history
+        BEFORE INSERT ON project_change_sets
+        BEGIN SELECT RAISE(ABORT, 'late history failure'); END;
+      `);
+      const object = objectSnapshot(null);
+      assert.throws(
+        () => new ExternalObjectNewCircuitProjectCommandRepository(context.db).execute({
+          projectId: "project-1",
+          expectedRevision: 0,
+          source: "user",
+          command: createExternalObjectNewCircuitProjectCommand(
+            externalObjectAssignToNewCircuitCommandType,
+            {
+              circuit: newExternalCircuit(context.db),
+              objects: [{
+                expected: object,
+                target: { ...object, circuitDeviceRowId: "row-new" },
+              }],
+              confirmedConflictObjectIds: [],
+            }
+          ),
+        }),
+        /late history failure/
+      );
+      assert.equal(
+        context.db.select().from(circuits).where(eq(circuits.id, "circuit-new")).get(),
+        undefined
+      );
+      assert.equal(context.db.select().from(externalModelObjects).get()!.circuitDeviceRowId, null);
+    } finally {
+      context.close();
+    }
+  });
+});