fix(sync): batch inserts + normalize nulls to avoid SQLite param mismatch

- Batch repository inserts with dynamic sizing under SQLite 999-param limit
- Normalize undefined → null to keep multi-row insert shapes consistent
- De-duplicate owned + starred repos by fullName (prefer starred variant)
- Enforce uniqueness via (user_id, full_name) + onConflictDoNothing
- Handle starred name collisions (suffix/prefix) across mirror + metadata
- Add repo-utils helpers + tests; guard Octokit.plugin in tests
- Remove manual unique index from entrypoint; rely on drizzle-kit migrations

src/lib/repo-utils.test.ts

@@ -0,0 +1,75 @@
+import { describe, it, expect } from 'bun:test';
+import { mergeGitReposPreferStarred, normalizeGitRepoToInsert, calcBatchSizeForInsert } from '@/lib/repo-utils';
+import type { GitRepo } from '@/types/Repository';
+
+function sampleRepo(overrides: Partial<GitRepo> = {}): GitRepo {
+  const base: GitRepo = {
+    name: 'repo',
+    fullName: 'owner/repo',
+    url: 'https://github.com/owner/repo',
+    cloneUrl: 'https://github.com/owner/repo.git',
+    owner: 'owner',
+    organization: undefined,
+    mirroredLocation: '',
+    destinationOrg: null,
+    isPrivate: false,
+    isForked: false,
+    forkedFrom: undefined,
+    hasIssues: true,
+    isStarred: false,
+    isArchived: false,
+    size: 1,
+    hasLFS: false,
+    hasSubmodules: false,
+    language: null,
+    description: null,
+    defaultBranch: 'main',
+    visibility: 'public',
+    status: 'imported',
+    lastMirrored: undefined,
+    errorMessage: undefined,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+  };
+  return { ...base, ...overrides };
+}
+
+describe('mergeGitReposPreferStarred', () => {
+  it('keeps unique repos', () => {
+    const basic = [sampleRepo({ fullName: 'a/x', name: 'x' })];
+    const starred: GitRepo[] = [];
+    const merged = mergeGitReposPreferStarred(basic, starred);
+    expect(merged).toHaveLength(1);
+    expect(merged[0].fullName).toBe('a/x');
+  });
+
+  it('prefers starred when duplicate exists', () => {
+    const basic = [sampleRepo({ fullName: 'a/x', name: 'x', isStarred: false })];
+    const starred = [sampleRepo({ fullName: 'a/x', name: 'x', isStarred: true })];
+    const merged = mergeGitReposPreferStarred(basic, starred);
+    expect(merged).toHaveLength(1);
+    expect(merged[0].isStarred).toBe(true);
+  });
+});
+
+describe('normalizeGitRepoToInsert', () => {
+  it('sets undefined optional fields to null', () => {
+    const repo = sampleRepo({ organization: undefined, forkedFrom: undefined, language: undefined, description: undefined, lastMirrored: undefined, errorMessage: undefined });
+    const insert = normalizeGitRepoToInsert(repo, { userId: 'u', configId: 'c' });
+    expect(insert.organization).toBeNull();
+    expect(insert.forkedFrom).toBeNull();
+    expect(insert.language).toBeNull();
+    expect(insert.description).toBeNull();
+    expect(insert.lastMirrored).toBeNull();
+    expect(insert.errorMessage).toBeNull();
+  });
+});
+
+describe('calcBatchSizeForInsert', () => {
+  it('respects 999 parameter limit', () => {
+    const batch = calcBatchSizeForInsert(29);
+    expect(batch).toBeGreaterThan(0);
+    expect(batch * 29).toBeLessThanOrEqual(999);
+  });
+});
+