feat: custom fields per project

Text, number, date or option-list fields defined in the project settings
(archived, never removed; their type is fixed once saved). Tickets hold
them, edited in the side panel, listed under the title and filtered by
option in the list view; also over GraphQL, REST (?field=ID:value) and MCP.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/openapi.json

@@ -2424,6 +2424,21 @@
               "type": "string"
             }
           },
+          {
+            "name": "field",
+            "required": false,
+            "in": "query",
+            "description": "Custom values the tickets must hold, as FIELD:value. Repeat the parameter for several",
+            "schema": {
+              "example": [
+                "BROWSER:Safari"
+              ],
+              "type": "array",
+              "items": {
+                "type": "string"
+              }
+            }
+          },
           {
             "name": "sort",
             "required": false,
@@ -10460,6 +10475,54 @@
           "archived"
         ]
       },
+      "CustomFieldType": {
+        "type": "string",
+        "enum": [
+          "TEXT",
+          "NUMBER",
+          "DATE",
+          "SELECT"
+        ],
+        "description": "DATE values are YYYY-MM-DD"
+      },
+      "CustomFieldDefinitionDto": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "string",
+            "example": "BROWSER"
+          },
+          "name": {
+            "type": "string",
+            "example": "Navegador"
+          },
+          "type": {
+            "description": "DATE values are YYYY-MM-DD",
+            "allOf": [
+              {
+                "$ref": "#/components/schemas/CustomFieldType"
+              }
+            ]
+          },
+          "options": {
+            "description": "The choices of a SELECT field",
+            "type": "array",
+            "items": {
+              "type": "string"
+            }
+          },
+          "archived": {
+            "type": "boolean"
+          }
+        },
+        "required": [
+          "id",
+          "name",
+          "type",
+          "options",
+          "archived"
+        ]
+      },
       "ProjectSettingsDto": {
         "type": "object",
         "properties": {
@@ -10487,13 +10550,20 @@
             "items": {
               "$ref": "#/components/schemas/AreaOptionDto"
             }
+          },
+          "customFields": {
+            "type": "array",
+            "items": {
+              "$ref": "#/components/schemas/CustomFieldDefinitionDto"
+            }
           }
         },
         "required": [
           "statuses",
           "transitions",
           "issueTypes",
-          "areas"
+          "areas",
+          "customFields"
         ]
       },
       "ProjectDto": {
@@ -10799,6 +10869,50 @@
           "name"
         ]
       },
+      "CustomFieldDefinitionBodyDto": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "string",
+            "example": "BROWSER"
+          },
+          "name": {
+            "type": "string",
+            "example": "Navegador",
+            "maxLength": 40
+          },
+          "type": {
+            "description": "Cannot change once the field exists. DATE: YYYY-MM-DD",
+            "allOf": [
+              {
+                "$ref": "#/components/schemas/CustomFieldType"
+              }
+            ]
+          },
+          "options": {
+            "maxItems": 50,
+            "example": [
+              "Chrome",
+              "Safari",
+              "Firefox"
+            ],
+            "description": "The choices of a SELECT field",
+            "type": "array",
+            "items": {
+              "type": "string"
+            }
+          },
+          "archived": {
+            "type": "boolean",
+            "default": false
+          }
+        },
+        "required": [
+          "id",
+          "name",
+          "type"
+        ]
+      },
       "ProjectSettingsBodyDto": {
         "type": "object",
         "properties": {
@@ -10826,6 +10940,13 @@
             "items": {
               "$ref": "#/components/schemas/AreaOptionBodyDto"
             }
+          },
+          "customFields": {
+            "description": "Absent: unchanged. Fields cannot be removed: archive them.",
+            "type": "array",
+            "items": {
+              "$ref": "#/components/schemas/CustomFieldDefinitionBodyDto"
+            }
           }
         },
         "required": [
@@ -11216,6 +11337,16 @@
             "nullable": true,
             "format": "date"
           },
+          "customFields": {
+            "type": "object",
+            "additionalProperties": {
+              "type": "string"
+            },
+            "example": {
+              "BROWSER": "Safari"
+            },
+            "description": "Custom field id → value (only those set)"
+          },
           "links": {
             "type": "array",
             "items": {
@@ -11321,6 +11452,7 @@
           "storyPoints",
           "startDate",
           "dueDate",
+          "customFields",
           "links",
           "attachments",
           "watchers",
@@ -11823,6 +11955,17 @@
             "nullable": true,
             "format": "date"
           },
+          "customFields": {
+            "type": "object",
+            "additionalProperties": {
+              "type": "string",
+              "nullable": true
+            },
+            "example": {
+              "BROWSER": "Safari"
+            },
+            "description": "Custom field id → value. Only the fields to change; null or '' clears one"
+          },
           "type": {
             "type": "string",
             "example": "BUG",
@@ -11950,6 +12093,17 @@
             "nullable": true,
             "format": "date"
           },
+          "customFields": {
+            "type": "object",
+            "additionalProperties": {
+              "type": "string",
+              "nullable": true
+            },
+            "example": {
+              "BROWSER": "Safari"
+            },
+            "description": "Custom field id → value. Only the fields to change; null or '' clears one"
+          },
           "type": {
             "type": "string",
             "example": "FEATURE",