refactor(P060): drop createField from the copilot bridge

Removes the bridge.createField method, CreateFieldArgs type, the
CREATE_FIELD BridgeRequestType variant, and the matching timeout-bucket
arm. The copilot demo never invoked it: create_field is not a registered
LLM tool (CLIENT_TOOL_NAMES omits it) and there are no direct
non-dispatcher consumers. Cleanup of dead surface — the iframe contract
itself still exposes CREATE_FIELD for SDK consumers, this only trims the
copilot's internal bridge.

Author: bendersej

copilot/src/lib/embed-bridge/bridge.ts

@@ -3,7 +3,6 @@ import {
   type BridgeRequestType,
   type BridgeResult,
   type BridgeState,
-  type CreateFieldArgs,
   type DocumentContentResult,
   type FieldRecord,
   type IframeBridge,
@@ -34,7 +33,6 @@ const getRequestTimeoutMs = (requestType: BridgeRequestType): number => {
     case 'DETECT_FIELDS':
     case 'GET_DOCUMENT_CONTENT':
       return HEAVY_REQUEST_TIMEOUT_MS
-    case 'CREATE_FIELD':
     case 'DELETE_FIELDS':
     case 'DELETE_PAGES':
     case 'FOCUS_FIELD':
@@ -389,16 +387,6 @@ export const createBridge = ({
     getFields: () => sendRequest<{ fields: FieldRecord[] }>('GET_FIELDS', {}),
     setFieldValue: ({ fieldId, value }) => sendRequest('SET_FIELD_VALUE', { field_id: fieldId, value }),
     focusField: ({ fieldId }) => sendRequest('FOCUS_FIELD', { field_id: fieldId }),
-    createField: ({ type, x, y, width, height, page, value }: CreateFieldArgs) =>
-      sendRequest<{ field_id: string }>('CREATE_FIELD', {
-        type,
-        x,
-        y,
-        width,
-        height,
-        page,
-        value: value ?? null,
-      }),
     submit: ({ downloadCopy }) => sendRequest('SUBMIT', { download_copy: downloadCopy }),
     download: () => sendRequest('DOWNLOAD', {}),
     movePage: ({ fromPage, toPage }) => sendRequest('MOVE_PAGE', { from_page: fromPage, to_page: toPage }),

copilot/src/lib/embed-bridge/index.ts

@@ -6,7 +6,6 @@ export type {
   BridgeRequestType,
   BridgeResult,
   BridgeState,
-  CreateFieldArgs,
   DeleteFieldsArgs,
   DocumentContentPage,
   DocumentContentResult,

copilot/src/lib/embed-bridge/types.ts

@@ -68,16 +68,6 @@ export type LoadDocumentArgs = {
   initialPage?: number
 }
 
-export type CreateFieldArgs = {
-  type: SupportedFieldType
-  x: number
-  y: number
-  width: number
-  height: number
-  page: number
-  value?: string | null
-}
-
 export type DeleteFieldsArgs = {
   fieldIds?: unknown
   page?: unknown
@@ -104,7 +94,6 @@ export type BridgeRequestType =
   | 'GET_FIELDS'
   | 'SET_FIELD_VALUE'
   | 'FOCUS_FIELD'
-  | 'CREATE_FIELD'
   | 'SUBMIT'
   | 'DOWNLOAD'
   | 'MOVE_PAGE'
@@ -131,7 +120,6 @@ export type IframeBridge = {
   focusField: (args: {
     fieldId: unknown
   }) => Promise<BridgeResult<{ hint: { type: 'user_action_expected'; message: string } } | null>>
-  createField: (args: CreateFieldArgs) => Promise<BridgeResult<{ field_id: string }>>
   submit: (args: { downloadCopy: boolean }) => Promise<BridgeResult>
   download: () => Promise<BridgeResult>
   movePage: (args: { fromPage: unknown; toPage: unknown }) => Promise<BridgeResult>