fix(knowledge): refuse a projection backfill page size that is not a positive integer

The page size is interpolated into the page statement and a page of
nothing would report the projection filled, so a payload that asks for
either is refused before the first page rather than quietly reshaped.

Claude-Session: https://claude.ai/code/session_01XU6c7pKRpa5CMoMHKDdqxX

Author: waleedlatif1

packages/db/script-migrations/0021_embedding_search_connector.test.ts

@@ -0,0 +1,28 @@
+/**
+ * @vitest-environment node
+ */
+import { backfillProjectionSourceAcl } from '@sim/db/script-migrations/0021_embedding_search_connector'
+import type { Sql } from 'postgres'
+import { describe, expect, it, vi } from 'vitest'
+
+/** A session that must never be reached: every case below is refused before the first page. */
+const untouched = { begin: vi.fn() } as unknown as Sql
+
+describe('backfillProjectionSourceAcl', () => {
+  it.each([0, -1, 1.5, Number.NaN, Number.POSITIVE_INFINITY])(
+    'refuses a page size of %s instead of reporting the projection filled',
+    async (pageSize) => {
+      await expect(
+        backfillProjectionSourceAcl(untouched, 'embedding_search', { pageSize })
+      ).rejects.toThrow('page size must be a positive integer')
+      expect(untouched.begin).not.toHaveBeenCalled()
+    }
+  )
+
+  it.each([-1, Number.NaN])('refuses a pause of %s', async (pauseMs) => {
+    await expect(
+      backfillProjectionSourceAcl(untouched, 'embedding_search', { pauseMs })
+    ).rejects.toThrow('pause must be a non-negative number')
+    expect(untouched.begin).not.toHaveBeenCalled()
+  })
+})

packages/db/script-migrations/0021_embedding_search_connector.ts

@@ -121,6 +121,16 @@ export async function backfillProjectionSourceAcl(
 ): Promise<ProjectionSourceAclBackfillProgress> {
   const pageSize = options.pageSize ?? PROJECTION_SOURCE_ACL_PAGE_SIZE
   const pauseMs = options.pauseMs ?? PROJECTION_SOURCE_ACL_PAGE_PAUSE_MS
+  /**
+   * The page size is interpolated into the statement and a page of nothing would report the
+   * projection filled; a payload that asks for either is refused rather than quietly reshaped.
+   */
+  if (!Number.isSafeInteger(pageSize) || pageSize < 1) {
+    throw new Error(`Projection backfill page size must be a positive integer, got ${pageSize}`)
+  }
+  if (!Number.isFinite(pauseMs) || pauseMs < 0) {
+    throw new Error(`Projection backfill pause must be a non-negative number, got ${pauseMs}`)
+  }
   const startedAt = Date.now()
   const deadline =
     options.budgetMs === undefined ? Number.POSITIVE_INFINITY : startedAt + options.budgetMs