chore: Update JSON importer to use zip streaming (#12380)

* chore: Update JSON importer to use zip streaming, new importer flow

* chore: Drop teamId from import urlId collision check and remove unused internal-id scaffolding

urlId is globally unique on Document/Collection so the team scope was wrong.
Also removes leftover internal-id generation in JSONAPIImportTask that was
never used in task input/output.

* Restore classes used upstream

shared/schema.ts

@@ -1,5 +1,9 @@
 import { z } from "zod";
-import type { IntegrationService, ProsemirrorDoc } from "./types";
+import type {
+  IntegrationService,
+  ProsemirrorData,
+  ProsemirrorDoc,
+} from "./types";
 import {
   CollectionPermission,
   type ImportableIntegrationService,
@@ -28,12 +32,20 @@ export type MarkdownImportInput = z.infer<
   typeof MarkdownImportInputItemSchema
 >[];
 
+export const JSONImportInputItemSchema = BaseImportInputItemSchema.extend({
+  externalId: z.string(),
+});
+
+export type JSONImportInput = z.infer<typeof JSONImportInputItemSchema>[];
+
 export type ImportInput<T extends ImportableIntegrationService> =
   T extends IntegrationService.Notion
     ? NotionImportInput
     : T extends IntegrationService.Markdown
       ? MarkdownImportInput
-      : BaseImportInput;
+      : T extends IntegrationService.JSON
+        ? JSONImportInput
+        : BaseImportInput;
 
 export const BaseImportTaskInputItemSchema = z.object({
   externalId: z.string(),
@@ -82,6 +94,36 @@ export interface MarkdownImportScratch {
   manifest?: MarkdownAttachmentManifestItem[];
 }
 
+/**
+ * Manifest entry describing a single attachment discovered during the JSON
+ * zip bootstrap phase. `externalId` is the attachment's original id from the
+ * export — used to rewrite `/api/attachments.redirect?id=<externalId>`
+ * references in document/collection content into new redirect URLs that point
+ * at the freshly created Attachment row (`id`).
+ */
+export const JSONAttachmentManifestItemSchema = z.object({
+  id: z.uuid(),
+  externalId: z.string(),
+  name: z.string(),
+  mimeType: z.string(),
+  pathInZip: z.string(),
+});
+
+export type JSONAttachmentManifestItem = z.infer<
+  typeof JSONAttachmentManifestItemSchema
+>;
+
+/**
+ * JSON importer scratch state. `storageKey` is set at import creation (it's
+ * the only durable handle on the uploaded zip). `manifest` is added by the
+ * bootstrap phase so the completion phase can re-download the zip and create
+ * Attachment rows without re-parsing the JSON files.
+ */
+export interface JSONImportScratch {
+  storageKey: string;
+  manifest?: JSONAttachmentManifestItem[];
+}
+
 /**
  * Per-importer scratch shape stored on `Import.scratch`. Holds cross-phase
  * state that the importer needs between bootstrap and completion but that
@@ -89,7 +131,11 @@ export interface MarkdownImportScratch {
  * `Processed`.
  */
 export type ImportScratch<T extends ImportableIntegrationService> =
-  T extends IntegrationService.Markdown ? MarkdownImportScratch : never;
+  T extends IntegrationService.Markdown
+    ? MarkdownImportScratch
+    : T extends IntegrationService.JSON
+      ? JSONImportScratch
+      : never;
 
 /**
  * Per-page task input. Generated by the bootstrap task and consumed by
@@ -124,22 +170,71 @@ export type MarkdownImportTaskInput = (
   | MarkdownPageImportTaskInputItem
 )[];
 
+/**
+ * Per-page task input for the JSON importer. Generated by the bootstrap task
+ * once the zip has been parsed; consumed by subsequent JSONAPIImportTask runs.
+ * `children` carries this document's direct descendants so each tree-depth
+ * runs as its own task wave, preserving parent-before-child ordering during
+ * persistence (createdAt of child tasks is strictly later than parents'). The
+ * type is defined as a TypeScript interface rather than via z.infer because
+ * it is only consumed internally — never validated at an API boundary — and
+ * zod's recursive-schema ergonomics aren't worth the cost here.
+ */
+export interface JSONPageImportTaskInputItem {
+  externalId: string;
+  parentExternalId?: string;
+  collectionExternalId?: string;
+  title: string;
+  urlId?: string;
+  icon?: string | null;
+  color?: string | null;
+  data: ProsemirrorData;
+  createdById?: string;
+  createdByName?: string;
+  createdByEmail?: string | null;
+  createdAt?: string;
+  updatedAt?: string;
+  publishedAt?: string | null;
+  /** Map of external attachment id → manifest entry id, scoped to this doc. */
+  attachmentIdMap: Record<string, string>;
+  children?: JSONPageImportTaskInputItem[];
+}
+
+/**
+ * JSON import task input — a bootstrap row carrying only the base placeholder
+ * item (the zip's `storageKey` lives on `Import.scratch`), or a page row
+ * carrying per-document content.
+ */
+export type JSONImportTaskInput = (
+  | BaseImportTaskInput[number]
+  | JSONPageImportTaskInputItem
+)[];
+
 export type ImportTaskInput<T extends ImportableIntegrationService> =
   T extends IntegrationService.Notion
     ? NotionImportTaskInput
     : T extends IntegrationService.Markdown
       ? MarkdownImportTaskInput
-      : BaseImportTaskInput;
+      : T extends IntegrationService.JSON
+        ? JSONImportTaskInput
+        : BaseImportTaskInput;
 
 // No reason to be here except for co-location with import task input.
 export type ImportTaskOutput = {
   externalId: string;
   title: string;
-  icon?: string;
+  icon?: string | null;
+  color?: string | null;
+  urlId?: string;
   author?: string;
+  /** Original author's id in the source system, used for user remapping. */
+  createdById?: string;
+  /** Original author's email in the source system, used for user remapping. */
+  createdByEmail?: string | null;
   content: ProsemirrorDoc;
   createdAt?: Date;
   updatedAt?: Date;
+  publishedAt?: Date | null;
 }[];
 
 export const IssueSource = z.object({

shared/types.ts

@@ -167,16 +167,20 @@ export enum IntegrationService {
   Figma = "figma",
   Notion = "notion",
   Markdown = "markdown",
+  JSON = "json",
 }
 
 export type ImportableIntegrationService = Extract<
   IntegrationService,
-  IntegrationService.Notion | IntegrationService.Markdown
+  | IntegrationService.Notion
+  | IntegrationService.Markdown
+  | IntegrationService.JSON
 >;
 
 export const ImportableIntegrationService = {
   Notion: IntegrationService.Notion,
   Markdown: IntegrationService.Markdown,
+  JSON: IntegrationService.JSON,
 } as const;
 
 export type IssueTrackerIntegrationService = Extract<