Add sandbox work-folder persistence and shared lifecycle

Introduce company-scoped task, agent, user and project files, recoverable trash, object-backed repository checkpoints, and a shared 180-second lifecycle for sandbox execution. Wire file browsing and save status into the owner surfaces. This is an implementation checkpoint; staging acceptance and the complete merge gate remain outstanding.

server/src/services/work-folder-garbage.ts

@@ -0,0 +1,44 @@
+import { and, eq, sql } from "drizzle-orm";
+import { workFolderObjects, workFiles, taskRepositoryBindings, type Db } from "@paperclipai/db";
+import type { StorageProvider } from "../storage/types.js";
+
+/** Record an upload before contacting storage, so abandoned bytes remain collectible. */
+export async function registerWorkFolderObject(db: Db, storage: StorageProvider, input: {
+  objectKey: string; companyId: string; folderId?: string; repositoryBindingId?: string;
+}) {
+  await db.insert(workFolderObjects).values({ ...input, provider: storage.id,
+    deleteAfter: new Date(Date.now() + 24 * 60 * 60 * 1000) }).onConflictDoUpdate({
+      target: workFolderObjects.objectKey,
+      set: { deleteAfter: sql`case when ${workFolderObjects.deleteAfter} is null then null else ${new Date(Date.now() + 24 * 60 * 60 * 1000).toISOString()}::timestamptz end` },
+    });
+}
+
+/** Bounded, retryable cleanup. Committed trash stays referenced until explicit purge. */
+export async function collectWorkFolderGarbage(db: Db, storage: StorageProvider, now = new Date(), limit = 100) {
+  // Polymorphic owners cannot use a single foreign key. Permanent deletion is
+  // detected against the authoritative owner tables, including auth users.
+  await db.execute(sql`delete from work_folders f where
+    (f.scope = 'task' and not exists (select 1 from issues i where i.id::text = f.owner_id and i.company_id = f.company_id)) or
+    (f.scope = 'agent' and not exists (select 1 from agents a where a.id::text = f.owner_id and a.company_id = f.company_id)) or
+    (f.scope = 'project' and not exists (select 1 from projects p where p.id::text = f.owner_id and p.company_id = f.company_id)) or
+    (f.scope = 'user' and not exists (select 1 from "user" u where u.id = f.owner_id))`);
+  let deleted = 0;
+  await db.transaction(async (tx) => {
+    const candidates = await tx.select().from(workFolderObjects).where(and(eq(workFolderObjects.provider, storage.id),
+      sql`(${workFolderObjects.deleteAfter} <= ${now.toISOString()}::timestamptz or (${workFolderObjects.deleteAfter} is null and (
+        (${workFolderObjects.folderId} is not null and not exists (select 1 from ${workFiles} where ${workFiles.objectKey} = ${workFolderObjects.objectKey})) or
+        (${workFolderObjects.repositoryBindingId} is not null and not exists (select 1 from ${taskRepositoryBindings} where ${taskRepositoryBindings.id} = ${workFolderObjects.repositoryBindingId}))
+      )))`,
+      sql`not exists (select 1 from ${workFiles} where ${workFiles.objectKey} = ${workFolderObjects.objectKey})`,
+    )).limit(Math.max(1, Math.min(limit, 1000))).for("update", { skipLocked: true });
+    for (const object of candidates) {
+      const prefix = object.folderId ? `${object.companyId}/work-folders/${object.folderId}/`
+        : `${object.companyId}/task-repositories/${object.repositoryBindingId}/`;
+      if (!object.objectKey.startsWith(prefix)) throw new Error("Work folder garbage ownership mismatch");
+      await storage.deleteObject({ objectKey: object.objectKey });
+      await tx.delete(workFolderObjects).where(eq(workFolderObjects.objectKey, object.objectKey));
+      deleted++;
+    }
+  });
+  return { deleted };
+}