diff --git a/docs/api/README.md b/docs/api/README.md
index 3f86b96..667c7dc 100644
--- a/docs/api/README.md
+++ b/docs/api/README.md
@@ -43,6 +43,10 @@ Generated from `@openapi` annotations in [`src/api/routes/`](../../src/api/route
 | [`routes/article/delete-image.md`](routes/article/delete-image.md) | `DELETE /article/{sku}/image/{fullHash}` |
 | [`routes/article/order-images.md`](routes/article/order-images.md) | `PUT /article/{sku}/images/order` |
 | [`routes/article/set-prices.md`](routes/article/set-prices.md) | `PUT /article/{sku}/prices` |
+| [`routes/article/supplier/list.md`](routes/article/supplier/list.md) | `GET /article/{sku}/supplier` |
+| [`routes/article/supplier/create.md`](routes/article/supplier/create.md) | `POST /article/{sku}/supplier` |
+| [`routes/article/supplier/delete.md`](routes/article/supplier/delete.md) | `DELETE /article/{sku}/supplier/{id}` |
+| [`routes/article/supplier/update.md`](routes/article/supplier/update.md) | `PATCH /article/{sku}/supplier/{id}` |
 | [`routes/article/set-weight.md`](routes/article/set-weight.md) | `PUT /article/{sku}/weight` |
 | [`routes/articleIndex.md`](routes/articleIndex.md) | `GET /articleIndex` |
 | [`routes/auth/login.md`](routes/auth/login.md) | `POST /auth/login` |
@@ -132,7 +136,7 @@ Clients subscribe via [`GET /events`](routes/events.md) (`text/event-stream`). A
 
 | Signal | Emitted by |
 |--------|------------|
-| `article-<sku>` | `PUT /article/{sku}/brand`, `PUT /article/{sku}/categories`, `PUT /article/{sku}/eans`, `POST /article/{sku}/image`, `DELETE /article/{sku}/image/{fullHash}`, `PUT /article/{sku}/images/order`, `PUT /article/{sku}/prices`, `PUT /article/{sku}/weight` |
+| `article-<sku>` | `PUT /article/{sku}/brand`, `PUT /article/{sku}/categories`, `PUT /article/{sku}/eans`, `POST /article/{sku}/image`, `DELETE /article/{sku}/image/{fullHash}`, `PUT /article/{sku}/images/order`, `PUT /article/{sku}/prices`, `POST /article/{sku}/supplier`, `DELETE /article/{sku}/supplier/{id}`, `PATCH /article/{sku}/supplier/{id}`, `PUT /article/{sku}/weight` |
 | `articles` | `POST /article`, `DELETE /article/{sku}`, `PATCH /article/{sku}` |
 | `category` | `POST /category`, `PUT /category/order`, `DELETE /category/{id}`, `PATCH /category/{id}`, `DELETE /category/{id}/image`, `POST /category/{id}/image` |
 
diff --git a/docs/api/openapi.json b/docs/api/openapi.json
index 4bb947b..c881230 100644
--- a/docs/api/openapi.json
+++ b/docs/api/openapi.json
@@ -762,7 +762,7 @@
           "Quote"
         ],
         "summary": "Create quote",
-        "description": "Creates a quote with header and lines in one transaction.\n`date` is the document date (valid-until).\n`entityId` must be a company customer (not Lieferanten/POS), or null.\nEach line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.\n",
+        "description": "Creates a quote with header and lines in one transaction.\n`date` is the document date (valid-until).\n`entityId` must be a company customer (not Lieferanten/POS), or null.\nEach line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.\n",
         "security": [
           {
             "cookieAuth": []
@@ -812,7 +812,7 @@
                       "pu": 1,
                       "amount": 10,
                       "net": 99.5,
-                      "tax": 19
+                      "taxrate": 19
                     }
                   ]
                 }
@@ -2014,7 +2014,7 @@
           "Order"
         ],
         "summary": "Create order",
-        "description": "Creates a sales order with header and lines in one transaction.\n`date` is the document date (expected delivery).\n`entityId` must be a company customer (not Lieferanten/POS), or null.\nEach line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.\n",
+        "description": "Creates a sales order with header and lines in one transaction.\n`date` is the document date (expected delivery).\n`entityId` must be a company customer (not Lieferanten/POS), or null.\nEach line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.\n",
         "security": [
           {
             "cookieAuth": []
@@ -2064,7 +2064,7 @@
                       "pu": 1,
                       "amount": 10,
                       "net": 99.5,
-                      "tax": 19
+                      "taxrate": 19
                     }
                   ]
                 }
@@ -4227,7 +4227,7 @@
           "Delivery"
         ],
         "summary": "Create delivery",
-        "description": "Creates a goods receipt with header and lines in one transaction.\nThe manifest `number` is allocated automatically via\n`nextNumber('delivery')`; the user-supplied reference is stored as\n`externalNumber`. Each line requires `sku` or `name`, `amount`, `net`, and\n`tax` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.\n",
+        "description": "Creates a goods receipt with header and lines in one transaction.\nThe manifest `number` is allocated automatically via\n`nextNumber('delivery')`; the user-supplied reference is stored as\n`externalNumber`. Each line requires `sku` or `name`, `amount`, `net`, and\n`taxrate` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.\n",
         "security": [
           {
             "cookieAuth": []
@@ -4276,7 +4276,7 @@
                       "pu": 1,
                       "amount": 10,
                       "net": 99.5,
-                      "tax": 19
+                      "taxrate": 19
                     }
                   ]
                 }
@@ -6735,6 +6735,460 @@
         }
       }
     },
+    "/article/{sku}/supplier": {
+      "get": {
+        "tags": [
+          "Article"
+        ],
+        "summary": "List article suppliers",
+        "description": "Fetches all suppliers linked to the specified article SKU.",
+        "security": [
+          {
+            "cookieAuth": []
+          }
+        ],
+        "x-markdown": "article/supplier/list.md",
+        "parameters": [
+          {
+            "in": "path",
+            "name": "sku",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Article SKU"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "List of suppliers linked to the article",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "suppliers": {
+                      "type": "array",
+                      "items": {
+                        "$ref": "#/components/schemas/ArticleSupplier"
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "No company selected or invalid sku",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Unauthorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "403": {
+            "description": "Not authorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Article or company not found",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          }
+        }
+      },
+      "post": {
+        "tags": [
+          "Article"
+        ],
+        "summary": "Assign supplier to article",
+        "description": "Assigns a supplier to an article with optional purchase price, stock, and supplier SKU.\n",
+        "security": [
+          {
+            "cookieAuth": []
+          }
+        ],
+        "x-signals": [
+          "article-<sku>"
+        ],
+        "x-markdown": "article/supplier/create.md",
+        "parameters": [
+          {
+            "in": "path",
+            "name": "sku",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Article SKU"
+          }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "type": "object",
+                "required": [
+                  "entityId"
+                ],
+                "properties": {
+                  "entityId": {
+                    "type": "integer",
+                    "description": "Supplier entity ID (in Lieferanten group)"
+                  },
+                  "sku": {
+                    "type": "string",
+                    "nullable": true,
+                    "description": "Supplier's item number"
+                  },
+                  "pu": {
+                    "type": "number",
+                    "default": 1,
+                    "description": "Packaging unit (VPE)"
+                  },
+                  "stock": {
+                    "type": "number",
+                    "nullable": true,
+                    "description": "Supplier stock"
+                  },
+                  "netPrice": {
+                    "type": "number",
+                    "nullable": true,
+                    "description": "Net purchase price"
+                  },
+                  "taxId": {
+                    "type": "integer",
+                    "nullable": true,
+                    "description": "Tax ID for purchase price"
+                  },
+                  "taxRate": {
+                    "type": "number",
+                    "nullable": true,
+                    "description": "Tax rate in percent"
+                  }
+                },
+                "example": {
+                  "entityId": 88,
+                  "sku": "MET-44910",
+                  "pu": 1,
+                  "stock": 140,
+                  "netPrice": 4.2,
+                  "taxId": 1
+                }
+              }
+            }
+          }
+        },
+        "responses": {
+          "201": {
+            "description": "Created supplier assignment",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "supplier": {
+                      "$ref": "#/components/schemas/ArticleSupplier"
+                    }
+                  }
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "entityId required, invalid pu, invalid stock, invalid price, or no company selected",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Unauthorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "403": {
+            "description": "Not authorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Article, supplier, or company not found",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "409": {
+            "description": "Supplier already assigned",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/article/{sku}/supplier/{id}": {
+      "patch": {
+        "tags": [
+          "Article"
+        ],
+        "summary": "Update article supplier assignment",
+        "description": "Updates an existing article-supplier association (supplier SKU, packaging unit, stock, purchase price).\n",
+        "security": [
+          {
+            "cookieAuth": []
+          }
+        ],
+        "x-signals": [
+          "article-<sku>"
+        ],
+        "x-markdown": "article/supplier/update.md",
+        "parameters": [
+          {
+            "in": "path",
+            "name": "sku",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Article SKU"
+          },
+          {
+            "in": "path",
+            "name": "id",
+            "required": true,
+            "schema": {
+              "type": "integer"
+            },
+            "description": "articlesupplier assignment ID"
+          }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "type": "object",
+                "properties": {
+                  "sku": {
+                    "type": "string",
+                    "nullable": true
+                  },
+                  "pu": {
+                    "type": "number"
+                  },
+                  "stock": {
+                    "type": "number",
+                    "nullable": true
+                  },
+                  "netPrice": {
+                    "type": "number",
+                    "nullable": true
+                  },
+                  "taxId": {
+                    "type": "integer",
+                    "nullable": true
+                  },
+                  "taxRate": {
+                    "type": "number",
+                    "nullable": true
+                  }
+                },
+                "example": {
+                  "sku": "MET-44910-B",
+                  "pu": 6,
+                  "stock": 95,
+                  "netPrice": 22.5
+                }
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Updated supplier assignment",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "supplier": {
+                      "$ref": "#/components/schemas/ArticleSupplier"
+                    }
+                  }
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "Invalid pu, invalid stock, invalid price, invalid id, or no company selected",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Unauthorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "403": {
+            "description": "Not authorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Supplier assignment, article, or company not found",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          }
+        }
+      },
+      "delete": {
+        "tags": [
+          "Article"
+        ],
+        "summary": "Remove supplier assignment from article",
+        "description": "Removes a supplier assignment from the article and cleans up its associated purchase price.\n",
+        "security": [
+          {
+            "cookieAuth": []
+          }
+        ],
+        "x-signals": [
+          "article-<sku>"
+        ],
+        "x-markdown": "article/supplier/delete.md",
+        "parameters": [
+          {
+            "in": "path",
+            "name": "sku",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Article SKU"
+          },
+          {
+            "in": "path",
+            "name": "id",
+            "required": true,
+            "schema": {
+              "type": "integer"
+            },
+            "description": "articlesupplier assignment ID"
+          }
+        ],
+        "responses": {
+          "204": {
+            "description": "Deleted"
+          },
+          "400": {
+            "description": "Invalid id, invalid sku, or no company selected",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Unauthorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "403": {
+            "description": "Not authorized",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Supplier assignment or article not found",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Error"
+                }
+              }
+            }
+          }
+        }
+      }
+    },
     "/article": {
       "post": {
         "tags": [
@@ -8680,6 +9134,74 @@
           }
         }
       },
+      "ArticleSupplierPrice": {
+        "type": "object",
+        "required": [
+          "net",
+          "taxId"
+        ],
+        "properties": {
+          "net": {
+            "type": "number",
+            "description": "Net purchase price"
+          },
+          "taxId": {
+            "type": "integer",
+            "description": "Tax ID"
+          },
+          "taxRate": {
+            "type": "number",
+            "nullable": true,
+            "description": "Tax rate in percent"
+          }
+        }
+      },
+      "ArticleSupplier": {
+        "type": "object",
+        "required": [
+          "id",
+          "articleId",
+          "entityId",
+          "pu"
+        ],
+        "properties": {
+          "id": {
+            "type": "integer"
+          },
+          "articleId": {
+            "type": "integer"
+          },
+          "entityId": {
+            "type": "integer"
+          },
+          "supplierName": {
+            "type": "string",
+            "nullable": true
+          },
+          "sku": {
+            "type": "string",
+            "nullable": true,
+            "description": "Supplier-specific SKU (Lieferanten-Art.-Nr.)"
+          },
+          "pu": {
+            "type": "number",
+            "description": "Packaging unit (Verpackungseinheit / VPE)"
+          },
+          "stock": {
+            "type": "number",
+            "nullable": true,
+            "description": "Supplier stock"
+          },
+          "priceId": {
+            "type": "integer",
+            "nullable": true
+          },
+          "price": {
+            "$ref": "#/components/schemas/ArticleSupplierPrice",
+            "nullable": true
+          }
+        }
+      },
       "Brand": {
         "type": "object",
         "required": [
@@ -8952,7 +9474,7 @@
           "amount",
           "net",
           "rebate",
-          "tax",
+          "taxrate",
           "comment"
         ],
         "properties": {
@@ -8981,9 +9503,9 @@
           "rebate": {
             "type": "number"
           },
-          "tax": {
+          "taxrate": {
             "type": "number",
-            "description": "tax.rate (manifestarticle.taxrate)"
+            "description": "Tax rate in percent (e.g. 19)"
           },
           "comment": {
             "type": "string",
@@ -8996,7 +9518,7 @@
         "required": [
           "amount",
           "net",
-          "tax"
+          "taxrate"
         ],
         "description": "Line item input. Requires `sku` or `name`.",
         "properties": {
@@ -9020,9 +9542,9 @@
           "net": {
             "type": "number"
           },
-          "tax": {
+          "taxrate": {
             "type": "number",
-            "description": "Tax rate (resolved via tax.ensure)"
+            "description": "Tax rate in percent (resolved via tax.ensure)"
           },
           "rebate": {
             "type": "number",
@@ -9065,7 +9587,7 @@
           "amount",
           "net",
           "rebate",
-          "tax",
+          "taxrate",
           "comment"
         ],
         "description": "Line shape for quote and order",
@@ -9095,9 +9617,9 @@
           "rebate": {
             "type": "number"
           },
-          "tax": {
+          "taxrate": {
             "type": "number",
-            "description": "tax.rate (manifestarticle.taxrate)"
+            "description": "Tax rate in percent (e.g. 19)"
           },
           "comment": {
             "type": "string",
@@ -9110,7 +9632,7 @@
         "required": [
           "amount",
           "net",
-          "tax"
+          "taxrate"
         ],
         "description": "Line item input. Requires `sku` or `name`.",
         "properties": {
@@ -9134,9 +9656,9 @@
           "net": {
             "type": "number"
           },
-          "tax": {
+          "taxrate": {
             "type": "number",
-            "description": "Tax rate (resolved via tax.ensure)"
+            "description": "Tax rate in percent (resolved via tax.ensure)"
           },
           "rebate": {
             "type": "number",
diff --git a/docs/api/routes/article/supplier/create.md b/docs/api/routes/article/supplier/create.md
new file mode 100644
index 0000000..e591022
--- /dev/null
+++ b/docs/api/routes/article/supplier/create.md
@@ -0,0 +1,69 @@
+# `POST /article/{sku}/supplier`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+Assign supplier to article
+
+Assigns a supplier to an article with optional purchase price, stock, and supplier SKU.
+
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `sku` | yes | string | Article SKU |
+
+## Body (JSON)
+
+```json
+{
+  "entityId": 88,
+  "sku": "MET-44910",
+  "pu": 1,
+  "stock": 140,
+  "netPrice": 4.2,
+  "taxId": 1
+}
+```
+
+## Signals
+
+On success, emits SSE signal: `article-<sku>` (see [`GET /events`](../events.md)).
+
+## Response `201`
+
+Created supplier assignment
+
+```json
+{
+  "supplier": {
+    "id": 1,
+    "articleId": 1,
+    "entityId": 1,
+    "supplierName": "…",
+    "sku": "…",
+    "pu": 1,
+    "stock": 1,
+    "priceId": 1,
+    "price": {
+      "net": 1,
+      "taxId": 1,
+      "taxRate": 1
+    }
+  }
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | entityId required, invalid pu, invalid stock, invalid price, or no company selected — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Article, supplier, or company not found — `{"error":"…"}` |
+| 409 | Supplier already assigned — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._
diff --git a/docs/api/routes/article/supplier/delete.md b/docs/api/routes/article/supplier/delete.md
new file mode 100644
index 0000000..98a95a6
--- /dev/null
+++ b/docs/api/routes/article/supplier/delete.md
@@ -0,0 +1,38 @@
+# `DELETE /article/{sku}/supplier/{id}`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+Remove supplier assignment from article
+
+Removes a supplier assignment from the article and cleans up its associated purchase price.
+
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `sku` | yes | string | Article SKU |
+| `id` | yes | integer | articlesupplier assignment ID |
+
+## Signals
+
+On success, emits SSE signal: `article-<sku>` (see [`GET /events`](../events.md)).
+
+## Response `204`
+
+Deleted
+
+_No content_
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | Invalid id, invalid sku, or no company selected — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Supplier assignment or article not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._
diff --git a/docs/api/routes/article/supplier/list.md b/docs/api/routes/article/supplier/list.md
new file mode 100644
index 0000000..a9f12e1
--- /dev/null
+++ b/docs/api/routes/article/supplier/list.md
@@ -0,0 +1,52 @@
+# `GET /article/{sku}/supplier`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+List article suppliers
+
+Fetches all suppliers linked to the specified article SKU.
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `sku` | yes | string | Article SKU |
+
+## Response `200`
+
+List of suppliers linked to the article
+
+```json
+{
+  "suppliers": [
+    {
+      "id": 1,
+      "articleId": 1,
+      "entityId": 1,
+      "supplierName": "…",
+      "sku": "…",
+      "pu": 1,
+      "stock": 1,
+      "priceId": 1,
+      "price": {
+        "net": 1,
+        "taxId": 1,
+        "taxRate": 1
+      }
+    }
+  ]
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | No company selected or invalid sku — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Article or company not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._
diff --git a/docs/api/routes/article/supplier/update.md b/docs/api/routes/article/supplier/update.md
new file mode 100644
index 0000000..a2e3f0c
--- /dev/null
+++ b/docs/api/routes/article/supplier/update.md
@@ -0,0 +1,67 @@
+# `PATCH /article/{sku}/supplier/{id}`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+Update article supplier assignment
+
+Updates an existing article-supplier association (supplier SKU, packaging unit, stock, purchase price).
+
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `sku` | yes | string | Article SKU |
+| `id` | yes | integer | articlesupplier assignment ID |
+
+## Body (JSON)
+
+```json
+{
+  "sku": "MET-44910-B",
+  "pu": 6,
+  "stock": 95,
+  "netPrice": 22.5
+}
+```
+
+## Signals
+
+On success, emits SSE signal: `article-<sku>` (see [`GET /events`](../events.md)).
+
+## Response `200`
+
+Updated supplier assignment
+
+```json
+{
+  "supplier": {
+    "id": 1,
+    "articleId": 1,
+    "entityId": 1,
+    "supplierName": "…",
+    "sku": "…",
+    "pu": 1,
+    "stock": 1,
+    "priceId": 1,
+    "price": {
+      "net": 1,
+      "taxId": 1,
+      "taxRate": 1
+    }
+  }
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | Invalid pu, invalid stock, invalid price, invalid id, or no company selected — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Supplier assignment, article, or company not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._
diff --git a/docs/api/routes/delivery/create.md b/docs/api/routes/delivery/create.md
index 9052b58..0ce285a 100644
--- a/docs/api/routes/delivery/create.md
+++ b/docs/api/routes/delivery/create.md
@@ -8,7 +8,7 @@ Creates a goods receipt with header and lines in one transaction.
 The manifest `number` is allocated automatically via
 `nextNumber('delivery')`; the user-supplied reference is stored as
 `externalNumber`. Each line requires `sku` or `name`, `amount`, `net`, and
-`tax` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.
+`taxrate` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.
 
 
 ## Body (JSON)
@@ -25,7 +25,7 @@ The manifest `number` is allocated automatically via
       "pu": 1,
       "amount": 10,
       "net": 99.5,
-      "tax": 19
+      "taxrate": 19
     }
   ]
 }
@@ -53,7 +53,7 @@ Created delivery
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/delivery/get.md b/docs/api/routes/delivery/get.md
index 089b64e..f09ae75 100644
--- a/docs/api/routes/delivery/get.md
+++ b/docs/api/routes/delivery/get.md
@@ -34,7 +34,7 @@ Delivery
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/delivery/update.md b/docs/api/routes/delivery/update.md
index 50d01a5..4bc0677 100644
--- a/docs/api/routes/delivery/update.md
+++ b/docs/api/routes/delivery/update.md
@@ -47,7 +47,7 @@ Updated delivery
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/order/create.md b/docs/api/routes/order/create.md
index 46ce39a..9a260a5 100644
--- a/docs/api/routes/order/create.md
+++ b/docs/api/routes/order/create.md
@@ -7,7 +7,7 @@ Create order
 Creates a sales order with header and lines in one transaction.
 `date` is the document date (expected delivery).
 `entityId` must be a company customer (not Lieferanten/POS), or null.
-Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
+Each line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
 
 
 ## Body (JSON)
@@ -24,7 +24,7 @@ Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defa
       "pu": 1,
       "amount": 10,
       "net": 99.5,
-      "tax": 19
+      "taxrate": 19
     }
   ]
 }
@@ -51,7 +51,7 @@ Created order
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/order/get.md b/docs/api/routes/order/get.md
index 8884458..aa03d9d 100644
--- a/docs/api/routes/order/get.md
+++ b/docs/api/routes/order/get.md
@@ -33,7 +33,7 @@ Order
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/order/update.md b/docs/api/routes/order/update.md
index a5bf854..a8dafcd 100644
--- a/docs/api/routes/order/update.md
+++ b/docs/api/routes/order/update.md
@@ -45,7 +45,7 @@ Updated order
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/quote/create.md b/docs/api/routes/quote/create.md
index d04b77e..aba0aa4 100644
--- a/docs/api/routes/quote/create.md
+++ b/docs/api/routes/quote/create.md
@@ -7,7 +7,7 @@ Create quote
 Creates a quote with header and lines in one transaction.
 `date` is the document date (valid-until).
 `entityId` must be a company customer (not Lieferanten/POS), or null.
-Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
+Each line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
 
 
 ## Body (JSON)
@@ -24,7 +24,7 @@ Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defa
       "pu": 1,
       "amount": 10,
       "net": 99.5,
-      "tax": 19
+      "taxrate": 19
     }
   ]
 }
@@ -51,7 +51,7 @@ Created quote
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/quote/get.md b/docs/api/routes/quote/get.md
index 9a18c19..dd17cff 100644
--- a/docs/api/routes/quote/get.md
+++ b/docs/api/routes/quote/get.md
@@ -33,7 +33,7 @@ Quote
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/docs/api/routes/quote/update.md b/docs/api/routes/quote/update.md
index 3f5271c..8670553 100644
--- a/docs/api/routes/quote/update.md
+++ b/docs/api/routes/quote/update.md
@@ -45,7 +45,7 @@ Updated quote
         "amount": 1,
         "net": 1,
         "rebate": 1,
-        "tax": 1,
+        "taxrate": 1,
         "comment": "…"
       }
     ]
diff --git a/package-lock.json b/package-lock.json
index 7b3e8e8..397a9e8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -59,9 +59,9 @@
       }
     },
     "node_modules/@alcalzone/ansi-tokenize": {
-      "version": "0.3.0",
-      "resolved": "https://registry.npmjs.org/@alcalzone/ansi-tokenize/-/ansi-tokenize-0.3.0.tgz",
-      "integrity": "sha512-p+CMKJ93HFmLkjXKlXiVGlMQEuRb6H0MokBSwUsX+S6BRX8eV5naFZpQJFfJHjRZY0Hmnqy1/r6UWl3x+19zYA==",
+      "version": "0.3.1",
+      "resolved": "https://registry.npmjs.org/@alcalzone/ansi-tokenize/-/ansi-tokenize-0.3.1.tgz",
+      "integrity": "sha512-cUD0PT0YX+rImRhfn7BfMRduP/tX/Zqt/N0dHlAyn2RlcJssCb5KsCJkhln61eh9vuJDkH8wKn3L8zJzzWXPFg==",
       "license": "MIT",
       "dependencies": {
         "ansi-styles": "^6.2.1",
@@ -342,33 +342,33 @@
       }
     },
     "node_modules/@azure/msal-browser": {
-      "version": "5.21.0",
-      "resolved": "https://registry.npmjs.org/@azure/msal-browser/-/msal-browser-5.21.0.tgz",
-      "integrity": "sha512-80OcuXDErmcEDAIH9pBtSqBsed2sPT/IWmbG3xHLoPMl5zc8TINd6SlJAbVSmN5huGa3xGAg5qR7VnpaIEK0Zw==",
+      "version": "5.22.0",
+      "resolved": "https://registry.npmjs.org/@azure/msal-browser/-/msal-browser-5.22.0.tgz",
+      "integrity": "sha512-5kgu9xeEKgGc2JeidxAtU15NJTqiH/CMCRRQAJ4Rac56kB7KVg91vbNmn+z3RO1vNomPN69UvjKG9h1Pghx6dQ==",
       "license": "MIT",
       "dependencies": {
-        "@azure/msal-common": "16.14.0"
+        "@azure/msal-common": "16.14.1"
       },
       "engines": {
         "node": ">=0.8.0"
       }
     },
     "node_modules/@azure/msal-common": {
-      "version": "16.14.0",
-      "resolved": "https://registry.npmjs.org/@azure/msal-common/-/msal-common-16.14.0.tgz",
-      "integrity": "sha512-A4rb55hI86Q9tBl/+jBj7TMz7iX2RFgQs/nExFzcAtoI/BFRVdaH5SL/MivrYD7qvweMpN8AgVvVMHV8UBYxew==",
+      "version": "16.14.1",
+      "resolved": "https://registry.npmjs.org/@azure/msal-common/-/msal-common-16.14.1.tgz",
+      "integrity": "sha512-Or6xhPNyi4zHW25158yxBoyxuCqNSPa5YBVqfF1J5Ks4MJWBo/USXdp05DQIPu1Zli00YZu6t0+h6KvHJealxQ==",
       "license": "MIT",
       "engines": {
         "node": ">=0.8.0"
       }
     },
     "node_modules/@azure/msal-node": {
-      "version": "6.0.0",
-      "resolved": "https://registry.npmjs.org/@azure/msal-node/-/msal-node-6.0.0.tgz",
-      "integrity": "sha512-PU0l3CsEZVm2K8vZNFxvgmM5d0Yx/sVL/axWW0hJBoeyiB6Q/uv7hXORb7EdzlNxvehsWEF82/o+/sXlIo+UIw==",
+      "version": "6.0.1",
+      "resolved": "https://registry.npmjs.org/@azure/msal-node/-/msal-node-6.0.1.tgz",
+      "integrity": "sha512-ixSO1Y/kCVRthRs+hSx/5qkwaunX1/RAePhlMN0wIpIQ4WEZ6AREGGnGd1AP0qspHVsAwzWQKGubpjh50JyJIQ==",
       "license": "MIT",
       "dependencies": {
-        "@azure/msal-common": "16.14.0",
+        "@azure/msal-common": "16.14.1",
         "jsonwebtoken": "^9.0.0"
       },
       "engines": {
@@ -969,12 +969,12 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "26.5.1",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.5.1.tgz",
-      "integrity": "sha512-CzNm2FezW4VR/LjG6yUdiEgLE/rAQ9Slj5gCu/C2VrdcW7I0ahNZ8DRbHT7zOZ6r3ONgd/bsQIeSaoDGrd1C6g==",
+      "version": "22.20.3",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-22.20.3.tgz",
+      "integrity": "sha512-DZmzkmwHzXrLPAXPyKNDzlIwMMUZCVacoD25ywdy5YTKGbOx/2ld+Q38Im2zJ0vBuZP5Prd3VZutKZyXwkOS8A==",
       "license": "MIT",
       "dependencies": {
-        "undici-types": "~8.9.0"
+        "undici-types": "~6.21.0"
       }
     },
     "node_modules/@types/readable-stream": {
@@ -1855,9 +1855,9 @@
       "license": "MIT"
     },
     "node_modules/fast-uri": {
-      "version": "3.1.7",
-      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.7.tgz",
-      "integrity": "sha512-dOvZVzjdZdz7phd9v6jCbwxrBW3fK6n8Rc0CtdmM4bumzMnxywBYhuph6J819RRw/ku+rLbelwfMunktuzVVHg==",
+      "version": "3.1.8",
+      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.8.tgz",
+      "integrity": "sha512-GZMtZUTNRpOVIECoXwLNZS5xUGE+mVNbTB8h/7Rwh2TFWcBQiPzTgyZi05BF9UMZKkLJv8XBRJTlU7zg8+ZfMg==",
       "dev": true,
       "funding": [
         {
@@ -2087,9 +2087,9 @@
       }
     },
     "node_modules/google-auth-library": {
-      "version": "11.0.2",
-      "resolved": "https://registry.npmjs.org/google-auth-library/-/google-auth-library-11.0.2.tgz",
-      "integrity": "sha512-vzpgPutxrghPsnjrjpzLX2bdv8IOL719Rh0oEjGnQu8YCIbnbMuTTQ5zU9LcKvLdOPgCxBwppbvnhgW90Qna5Q==",
+      "version": "11.1.0",
+      "resolved": "https://registry.npmjs.org/google-auth-library/-/google-auth-library-11.1.0.tgz",
+      "integrity": "sha512-YIBq5KNoHQrZ9PM4PeodDBqqBGlSTIxh1zibN8u3zNIO9UJg8gvKuCpdKV7fWXhsZ2zRkU6FhGrgKNgLJ2IRgw==",
       "license": "Apache-2.0",
       "dependencies": {
         "base64-js": "^1.3.0",
@@ -3715,9 +3715,9 @@
       }
     },
     "node_modules/undici-types": {
-      "version": "8.9.0",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-8.9.0.tgz",
-      "integrity": "sha512-KTDyRTYX8sWmKXAikPHHSyc63CRPETMctyjKFupcC6OBLXT3xsN0e9aF7m+mIXutFWpUXuedtowG7iLOzp0kQg==",
+      "version": "6.21.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.21.0.tgz",
+      "integrity": "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==",
       "license": "MIT"
     },
     "node_modules/unpipe": {
diff --git a/src/api/openapi.js b/src/api/openapi.js
index 25ebbed..656cbab 100644
--- a/src/api/openapi.js
+++ b/src/api/openapi.js
@@ -108,6 +108,50 @@
  *           format: date-time
  *         text:
  *           type: string
+ *     ArticleSupplierPrice:
+ *       type: object
+ *       required: [net, taxId]
+ *       properties:
+ *         net:
+ *           type: number
+ *           description: Net purchase price
+ *         taxId:
+ *           type: integer
+ *           description: Tax ID
+ *         taxRate:
+ *           type: number
+ *           nullable: true
+ *           description: Tax rate in percent
+ *     ArticleSupplier:
+ *       type: object
+ *       required: [id, articleId, entityId, pu]
+ *       properties:
+ *         id:
+ *           type: integer
+ *         articleId:
+ *           type: integer
+ *         entityId:
+ *           type: integer
+ *         supplierName:
+ *           type: string
+ *           nullable: true
+ *         sku:
+ *           type: string
+ *           nullable: true
+ *           description: Supplier-specific SKU (Lieferanten-Art.-Nr.)
+ *         pu:
+ *           type: number
+ *           description: Packaging unit (Verpackungseinheit / VPE)
+ *         stock:
+ *           type: number
+ *           nullable: true
+ *           description: Supplier stock
+ *         priceId:
+ *           type: integer
+ *           nullable: true
+ *         price:
+ *           $ref: '#/components/schemas/ArticleSupplierPrice'
+ *           nullable: true
  *     Brand:
  *       type: object
  *       required: [id, name]
@@ -264,7 +308,7 @@
  *           format: date-time
  *     DeliveryLine:
  *       type: object
- *       required: [id, sku, name, pu, amount, net, rebate, tax, comment]
+ *       required: [id, sku, name, pu, amount, net, rebate, taxrate, comment]
  *       properties:
  *         id:
  *           type: integer
@@ -284,15 +328,15 @@
  *           type: number
  *         rebate:
  *           type: number
- *         tax:
+ *         taxrate:
  *           type: number
- *           description: tax.rate (manifestarticle.taxrate)
+ *           description: Tax rate in percent (e.g. 19)
  *         comment:
  *           type: string
  *           nullable: true
  *     DeliveryLineInput:
  *       type: object
- *       required: [amount, net, tax]
+ *       required: [amount, net, taxrate]
  *       description: Line item input. Requires `sku` or `name`.
  *       properties:
  *         sku:
@@ -310,9 +354,9 @@
  *           type: number
  *         net:
  *           type: number
- *         tax:
+ *         taxrate:
  *           type: number
- *           description: Tax rate (resolved via tax.ensure)
+ *           description: Tax rate in percent (resolved via tax.ensure)
  *         rebate:
  *           type: number
  *           description: Defaults to 0
@@ -331,7 +375,7 @@
  *                 $ref: '#/components/schemas/DeliveryLine'
  *     ManifestLine:
  *       type: object
- *       required: [id, sku, name, pu, amount, net, rebate, tax, comment]
+ *       required: [id, sku, name, pu, amount, net, rebate, taxrate, comment]
  *       description: Line shape for quote and order
  *       properties:
  *         id:
@@ -352,15 +396,15 @@
  *           type: number
  *         rebate:
  *           type: number
- *         tax:
+ *         taxrate:
  *           type: number
- *           description: tax.rate (manifestarticle.taxrate)
+ *           description: Tax rate in percent (e.g. 19)
  *         comment:
  *           type: string
  *           nullable: true
  *     ManifestLineInput:
  *       type: object
- *       required: [amount, net, tax]
+ *       required: [amount, net, taxrate]
  *       description: Line item input. Requires `sku` or `name`.
  *       properties:
  *         sku:
@@ -378,9 +422,9 @@
  *           type: number
  *         net:
  *           type: number
- *         tax:
+ *         taxrate:
  *           type: number
- *           description: Tax rate (resolved via tax.ensure)
+ *           description: Tax rate in percent (resolved via tax.ensure)
  *         rebate:
  *           type: number
  *           description: Defaults to 0
diff --git a/src/api/routes/articlesupplier.js b/src/api/routes/articlesupplier.js
new file mode 100644
index 0000000..da6040f
--- /dev/null
+++ b/src/api/routes/articlesupplier.js
@@ -0,0 +1,487 @@
+import * as db from '../../db/articlesupplier.js';
+import { emit } from '../sse.js';
+
+function requireSelectedCompany(req) {
+    const companyId = req.user?.selectedCompanyId;
+    if (companyId == null) {
+        return { error: 'No company selected' };
+    }
+    return { companyId };
+}
+
+function parseSku(value) {
+    const sku = typeof value === 'string' ? value.trim() : '';
+    if (!sku) return { error: 'sku is required' };
+    return { sku: decodeURIComponent(sku) };
+}
+
+function parsePositiveInt(value, field) {
+    const id = Number(value);
+    if (!Number.isInteger(id) || id <= 0) {
+        return { error: `${field} is required` };
+    }
+    return { id };
+}
+
+function emitArticleSignal(req, sku) {
+    const companyId = req.user?.selectedCompanyId;
+    if (companyId == null) return;
+    emit(`article-${sku}`, { companyId });
+}
+
+function articleSupplierErrorStatus(error) {
+    if (error.message === 'No company selected') return 400;
+    if (error.message === 'Not authorized') return 403;
+    if (error.message === 'Company not found') return 404;
+    if (error.message === 'Article not found') return 404;
+    if (error.message === 'Supplier not found') return 404;
+    if (error.message === 'Supplier assignment not found') return 404;
+    if (error.message === 'Supplier already assigned') return 409;
+    if (error.message === 'Supplier required' || error.message === 'entityId is required') return 400;
+    if (error.message === 'Invalid pu' || error.message === 'pu must be greater than 0') return 400;
+    if (error.message === 'Invalid stock') return 400;
+    if (error.message === 'Invalid price') return 400;
+    if (error.message === 'sku is required') return 400;
+    if (error.message === 'id is required') return 400;
+    return 500;
+}
+
+/**
+ * Registers article supplier routes under `/article/:sku/supplier`.
+ * @param {import('express').Application} app
+ * @param {string} [basePath='']
+ */
+export function register(app, basePath = '') {
+    /**
+     * @openapi
+     * /article/{sku}/supplier:
+     *   get:
+     *     tags: [Article]
+     *     summary: List article suppliers
+     *     description: Fetches all suppliers linked to the specified article SKU.
+     *     security:
+     *       - cookieAuth: []
+     *     x-markdown: article/supplier/list.md
+     *     parameters:
+     *       - in: path
+     *         name: sku
+     *         required: true
+     *         schema:
+     *           type: string
+     *         description: Article SKU
+     *     responses:
+     *       200:
+     *         description: List of suppliers linked to the article
+     *         content:
+     *           application/json:
+     *             schema:
+     *               type: object
+     *               properties:
+     *                 suppliers:
+     *                   type: array
+     *                   items:
+     *                     $ref: '#/components/schemas/ArticleSupplier'
+     *       400:
+     *         description: No company selected or invalid sku
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       401:
+     *         description: Unauthorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       403:
+     *         description: Not authorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       404:
+     *         description: Article or company not found
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *   post:
+     *     tags: [Article]
+     *     summary: Assign supplier to article
+     *     description: |
+     *       Assigns a supplier to an article with optional purchase price, stock, and supplier SKU.
+     *     security:
+     *       - cookieAuth: []
+     *     x-signals: [article-<sku>]
+     *     x-markdown: article/supplier/create.md
+     *     parameters:
+     *       - in: path
+     *         name: sku
+     *         required: true
+     *         schema:
+     *           type: string
+     *         description: Article SKU
+     *     requestBody:
+     *       required: true
+     *       content:
+     *         application/json:
+     *           schema:
+     *             type: object
+     *             required: [entityId]
+     *             properties:
+     *               entityId:
+     *                 type: integer
+     *                 description: Supplier entity ID (in Lieferanten group)
+     *               sku:
+     *                 type: string
+     *                 nullable: true
+     *                 description: Supplier's item number
+     *               pu:
+     *                 type: number
+     *                 default: 1
+     *                 description: Packaging unit (VPE)
+     *               stock:
+     *                 type: number
+     *                 nullable: true
+     *                 description: Supplier stock
+     *               netPrice:
+     *                 type: number
+     *                 nullable: true
+     *                 description: Net purchase price
+     *               taxId:
+     *                 type: integer
+     *                 nullable: true
+     *                 description: Tax ID for purchase price
+     *               taxRate:
+     *                 type: number
+     *                 nullable: true
+     *                 description: Tax rate in percent
+     *             example:
+     *               entityId: 88
+     *               sku: MET-44910
+     *               pu: 1
+     *               stock: 140
+     *               netPrice: 4.20
+     *               taxId: 1
+     *     responses:
+     *       201:
+     *         description: Created supplier assignment
+     *         content:
+     *           application/json:
+     *             schema:
+     *               type: object
+     *               properties:
+     *                 supplier:
+     *                   $ref: '#/components/schemas/ArticleSupplier'
+     *       400:
+     *         description: entityId required, invalid pu, invalid stock, invalid price, or no company selected
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       401:
+     *         description: Unauthorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       403:
+     *         description: Not authorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       404:
+     *         description: Article, supplier, or company not found
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       409:
+     *         description: Supplier already assigned
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     */
+    app.get(`${basePath}/article/:sku/supplier`, async (req, res) => {
+        const selected = requireSelectedCompany(req);
+        if (selected.error) {
+            return res.status(400).json({ error: selected.error });
+        }
+
+        const skuParsed = parseSku(req.params.sku);
+        if (skuParsed.error) {
+            return res.status(400).json({ error: skuParsed.error });
+        }
+
+        try {
+            const suppliers = await db.listByArticleSku(req.user.id, skuParsed.sku);
+            res.status(200).json({ suppliers });
+        } catch (error) {
+            const status = articleSupplierErrorStatus(error);
+            if (status === 500) console.error('List article suppliers failed:', error);
+            res.status(status).json({ error: error.message });
+        }
+    });
+
+    app.post(`${basePath}/article/:sku/supplier`, async (req, res) => {
+        const selected = requireSelectedCompany(req);
+        if (selected.error) {
+            return res.status(400).json({ error: selected.error });
+        }
+
+        const skuParsed = parseSku(req.params.sku);
+        if (skuParsed.error) {
+            return res.status(400).json({ error: skuParsed.error });
+        }
+
+        const { entityId, sku: supplierSku, pu, stock, netPrice, taxId, taxRate } = req.body ?? {};
+        if (entityId == null || !Number.isFinite(entityId)) {
+            return res.status(400).json({ error: 'entityId is required' });
+        }
+        if (pu !== undefined && pu !== null && (!Number.isFinite(pu) || pu <= 0)) {
+            return res.status(400).json({ error: 'pu must be greater than 0' });
+        }
+        if (stock !== undefined && stock !== null && !Number.isFinite(stock)) {
+            return res.status(400).json({ error: 'Invalid stock' });
+        }
+        if (netPrice !== undefined && netPrice !== null && !Number.isFinite(netPrice)) {
+            return res.status(400).json({ error: 'Invalid price' });
+        }
+
+        try {
+            const supplier = await db.create(req.user.id, skuParsed.sku, {
+                entityId,
+                sku: supplierSku,
+                pu,
+                stock,
+                netPrice,
+                taxId,
+                taxRate,
+            });
+            emitArticleSignal(req, skuParsed.sku);
+            res.status(201).json({ supplier });
+        } catch (error) {
+            const status = articleSupplierErrorStatus(error);
+            if (status === 500) console.error('Create article supplier failed:', error);
+            res.status(status).json({ error: error.message });
+        }
+    });
+
+    /**
+     * @openapi
+     * /article/{sku}/supplier/{id}:
+     *   patch:
+     *     tags: [Article]
+     *     summary: Update article supplier assignment
+     *     description: |
+     *       Updates an existing article-supplier association (supplier SKU, packaging unit, stock, purchase price).
+     *     security:
+     *       - cookieAuth: []
+     *     x-signals: [article-<sku>]
+     *     x-markdown: article/supplier/update.md
+     *     parameters:
+     *       - in: path
+     *         name: sku
+     *         required: true
+     *         schema:
+     *           type: string
+     *         description: Article SKU
+     *       - in: path
+     *         name: id
+     *         required: true
+     *         schema:
+     *           type: integer
+     *         description: articlesupplier assignment ID
+     *     requestBody:
+     *       required: true
+     *       content:
+     *         application/json:
+     *           schema:
+     *             type: object
+     *             properties:
+     *               sku:
+     *                 type: string
+     *                 nullable: true
+     *               pu:
+     *                 type: number
+     *               stock:
+     *                 type: number
+     *                 nullable: true
+     *               netPrice:
+     *                 type: number
+     *                 nullable: true
+     *               taxId:
+     *                 type: integer
+     *                 nullable: true
+     *               taxRate:
+     *                 type: number
+     *                 nullable: true
+     *             example:
+     *               sku: MET-44910-B
+     *               pu: 6
+     *               stock: 95
+     *               netPrice: 22.50
+     *     responses:
+     *       200:
+     *         description: Updated supplier assignment
+     *         content:
+     *           application/json:
+     *             schema:
+     *               type: object
+     *               properties:
+     *                 supplier:
+     *                   $ref: '#/components/schemas/ArticleSupplier'
+     *       400:
+     *         description: Invalid pu, invalid stock, invalid price, invalid id, or no company selected
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       401:
+     *         description: Unauthorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       403:
+     *         description: Not authorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       404:
+     *         description: Supplier assignment, article, or company not found
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *   delete:
+     *     tags: [Article]
+     *     summary: Remove supplier assignment from article
+     *     description: |
+     *       Removes a supplier assignment from the article and cleans up its associated purchase price.
+     *     security:
+     *       - cookieAuth: []
+     *     x-signals: [article-<sku>]
+     *     x-markdown: article/supplier/delete.md
+     *     parameters:
+     *       - in: path
+     *         name: sku
+     *         required: true
+     *         schema:
+     *           type: string
+     *         description: Article SKU
+     *       - in: path
+     *         name: id
+     *         required: true
+     *         schema:
+     *           type: integer
+     *         description: articlesupplier assignment ID
+     *     responses:
+     *       204:
+     *         description: Deleted
+     *       400:
+     *         description: Invalid id, invalid sku, or no company selected
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       401:
+     *         description: Unauthorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       403:
+     *         description: Not authorized
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     *       404:
+     *         description: Supplier assignment or article not found
+     *         content:
+     *           application/json:
+     *             schema:
+     *               $ref: '#/components/schemas/Error'
+     */
+    app.patch(`${basePath}/article/:sku/supplier/:id`, async (req, res) => {
+        const selected = requireSelectedCompany(req);
+        if (selected.error) {
+            return res.status(400).json({ error: selected.error });
+        }
+
+        const skuParsed = parseSku(req.params.sku);
+        if (skuParsed.error) {
+            return res.status(400).json({ error: skuParsed.error });
+        }
+
+        const idParsed = parsePositiveInt(req.params.id, 'id');
+        if (idParsed.error) {
+            return res.status(400).json({ error: idParsed.error });
+        }
+
+        const body = req.body ?? {};
+        const patch = {};
+        if (body.sku !== undefined) patch.sku = body.sku;
+        if (body.pu !== undefined) {
+            if (body.pu === null || !Number.isFinite(body.pu) || body.pu <= 0) {
+                return res.status(400).json({ error: 'pu must be greater than 0' });
+            }
+            patch.pu = body.pu;
+        }
+        if (body.stock !== undefined) {
+            if (body.stock !== null && !Number.isFinite(body.stock)) {
+                return res.status(400).json({ error: 'Invalid stock' });
+            }
+            patch.stock = body.stock;
+        }
+        if (body.netPrice !== undefined) {
+            if (body.netPrice !== null && !Number.isFinite(body.netPrice)) {
+                return res.status(400).json({ error: 'Invalid price' });
+            }
+            patch.netPrice = body.netPrice;
+        }
+        if (body.taxId !== undefined) patch.taxId = body.taxId;
+        if (body.taxRate !== undefined) patch.taxRate = body.taxRate;
+
+        try {
+            const supplier = await db.update(req.user.id, skuParsed.sku, idParsed.id, patch);
+            emitArticleSignal(req, skuParsed.sku);
+            res.status(200).json({ supplier });
+        } catch (error) {
+            const status = articleSupplierErrorStatus(error);
+            if (status === 500) console.error('Update article supplier failed:', error);
+            res.status(status).json({ error: error.message });
+        }
+    });
+
+    app.delete(`${basePath}/article/:sku/supplier/:id`, async (req, res) => {
+        const selected = requireSelectedCompany(req);
+        if (selected.error) {
+            return res.status(400).json({ error: selected.error });
+        }
+
+        const skuParsed = parseSku(req.params.sku);
+        if (skuParsed.error) {
+            return res.status(400).json({ error: skuParsed.error });
+        }
+
+        const idParsed = parsePositiveInt(req.params.id, 'id');
+        if (idParsed.error) {
+            return res.status(400).json({ error: idParsed.error });
+        }
+
+        try {
+            await db.remove(req.user.id, skuParsed.sku, idParsed.id);
+            emitArticleSignal(req, skuParsed.sku);
+            res.sendStatus(204);
+        } catch (error) {
+            const status = articleSupplierErrorStatus(error);
+            if (status === 500) console.error('Delete article supplier failed:', error);
+            res.status(status).json({ error: error.message });
+        }
+    });
+}
diff --git a/src/api/routes/delivery.js b/src/api/routes/delivery.js
index 74d5aa9..1d65ced 100644
--- a/src/api/routes/delivery.js
+++ b/src/api/routes/delivery.js
@@ -82,7 +82,7 @@ export function register(app, basePath = '') {
      *       The manifest `number` is allocated automatically via
      *       `nextNumber('delivery')`; the user-supplied reference is stored as
      *       `externalNumber`. Each line requires `sku` or `name`, `amount`, `net`, and
-     *       `tax` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.
+     *       `taxrate` (rate). `pu` defaults to `1`; `rebate` defaults to `0`.
      *     security:
      *       - cookieAuth: []
      *     x-markdown: delivery/create.md
@@ -117,7 +117,7 @@ export function register(app, basePath = '') {
      *                   pu: 1
      *                   amount: 10
      *                   net: 99.5
-     *                   tax: 19
+     *                   taxrate: 19
      *     responses:
      *       201:
      *         description: Created delivery
diff --git a/src/api/routes/order.js b/src/api/routes/order.js
index 7771326..241a9d0 100644
--- a/src/api/routes/order.js
+++ b/src/api/routes/order.js
@@ -81,7 +81,7 @@ export function register(app, basePath = '') {
      *       Creates a sales order with header and lines in one transaction.
      *       `date` is the document date (expected delivery).
      *       `entityId` must be a company customer (not Lieferanten/POS), or null.
-     *       Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
+     *       Each line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
      *     security:
      *       - cookieAuth: []
      *     x-markdown: order/create.md
@@ -117,7 +117,7 @@ export function register(app, basePath = '') {
      *                   pu: 1
      *                   amount: 10
      *                   net: 99.5
-     *                   tax: 19
+     *                   taxrate: 19
      *     responses:
      *       201:
      *         description: Created order
diff --git a/src/api/routes/quote.js b/src/api/routes/quote.js
index 11c8678..b1bc861 100644
--- a/src/api/routes/quote.js
+++ b/src/api/routes/quote.js
@@ -81,7 +81,7 @@ export function register(app, basePath = '') {
      *       Creates a quote with header and lines in one transaction.
      *       `date` is the document date (valid-until).
      *       `entityId` must be a company customer (not Lieferanten/POS), or null.
-     *       Each line requires `sku` or `name`, `amount`, `net`, and `tax` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
+     *       Each line requires `sku` or `name`, `amount`, `net`, and `taxrate` (rate); `pu` defaults to `1`; `rebate` defaults to `0`.
      *     security:
      *       - cookieAuth: []
      *     x-markdown: quote/create.md
@@ -117,7 +117,7 @@ export function register(app, basePath = '') {
      *                   pu: 1
      *                   amount: 10
      *                   net: 99.5
-     *                   tax: 19
+     *                   taxrate: 19
      *     responses:
      *       201:
      *         description: Created quote
diff --git a/src/db/articlesupplier.js b/src/db/articlesupplier.js
new file mode 100644
index 0000000..6150506
--- /dev/null
+++ b/src/db/articlesupplier.js
@@ -0,0 +1,21 @@
+import { getStore } from './store.js';
+
+export async function listByArticleSku(googleAuthId, sku) {
+    const store = await getStore();
+    return store.articlesupplier.listByArticleSku(googleAuthId, sku);
+}
+
+export async function create(googleAuthId, sku, data) {
+    const store = await getStore();
+    return store.articlesupplier.create(googleAuthId, sku, data);
+}
+
+export async function update(googleAuthId, sku, id, data) {
+    const store = await getStore();
+    return store.articlesupplier.update(googleAuthId, sku, id, data);
+}
+
+export async function remove(googleAuthId, sku, id) {
+    const store = await getStore();
+    return store.articlesupplier.delete(googleAuthId, sku, id);
+}
diff --git a/src/db/store.js b/src/db/store.js
index 3e16611..0ed663b 100644
--- a/src/db/store.js
+++ b/src/db/store.js
@@ -29,6 +29,7 @@ const STORE_NAMESPACES = [
     'order',
     'numbers',
     'companysetting',
+    'articlesupplier',
 ];
 
 /**