---
phase: 29
plan: 04
type: backend
wave: 2
depends_on: [01]
files_modified:
  - scripts/backfill-dominant-colors.ts
autonomous: true
requirements: []
---

<objective>
Create a one-time backfill script that processes all existing images in the database to extract and store their dominant color. Handles items, globalItems, and threadCandidates with imageFilename, plus globalItems with external imageUrl.
</objective>

<tasks>

### Task 1: Create backfill script
<task type="code">
<read_first>
- src/db/schema.ts
- src/server/services/storage.service.ts
- src/server/services/image.service.ts
</read_first>
<action>
Create `scripts/backfill-dominant-colors.ts`:

```ts
/**
 * Backfill dominant colors for all existing images.
 * Run with: bun run scripts/backfill-dominant-colors.ts
 *
 * Idempotent — skips records that already have dominantColor set.
 * Processes in batches of 10 concurrent requests.
 */

import { GetObjectCommand, S3Client } from "@aws-sdk/client-s3";
import { drizzle } from "drizzle-orm/postgres-js";
import { isNull } from "drizzle-orm";
import postgres from "postgres";
import sharp from "sharp";
import * as schema from "../src/db/schema";

const DATABASE_URL = process.env.DATABASE_URL;
if (!DATABASE_URL) throw new Error("DATABASE_URL required");

const client = postgres(DATABASE_URL);
const db = drizzle(client, { schema });

const s3 = new S3Client({
  endpoint: process.env.S3_ENDPOINT,
  region: process.env.S3_REGION ?? "us-east-1",
  credentials: {
    accessKeyId: process.env.S3_ACCESS_KEY!,
    secretAccessKey: process.env.S3_SECRET_KEY!,
  },
  forcePathStyle: true,
});
const bucket = process.env.S3_BUCKET ?? "gearbox-images";

async function extractColor(buffer: Buffer): Promise<string | null> {
  try {
    const { data } = await sharp(buffer).resize(1, 1).raw().toBuffer({ resolveWithObject: true });
    return `#${data[0].toString(16).padStart(2, "0")}${data[1].toString(16).padStart(2, "0")}${data[2].toString(16).padStart(2, "0")}`;
  } catch {
    return null;
  }
}

async function fetchFromS3(filename: string): Promise<Buffer | null> {
  try {
    const response = await s3.send(new GetObjectCommand({ Bucket: bucket, Key: filename }));
    const bytes = await response.Body?.transformToByteArray();
    return bytes ? Buffer.from(bytes) : null;
  } catch {
    return null;
  }
}

async function fetchFromUrl(url: string): Promise<Buffer | null> {
  try {
    const response = await fetch(url, { signal: AbortSignal.timeout(10000) });
    if (!response.ok) return null;
    return Buffer.from(await response.arrayBuffer());
  } catch {
    return null;
  }
}

async function processBatch<T extends { id: number }>(
  items: T[],
  getBuffer: (item: T) => Promise<Buffer | null>,
  updateFn: (id: number, color: string) => Promise<void>,
  label: string,
) {
  const BATCH_SIZE = 10;
  let processed = 0;
  let updated = 0;
  let failed = 0;

  for (let i = 0; i < items.length; i += BATCH_SIZE) {
    const batch = items.slice(i, i + BATCH_SIZE);
    const results = await Promise.allSettled(
      batch.map(async (item) => {
        const buffer = await getBuffer(item);
        if (!buffer) { failed++; return; }
        const color = await extractColor(buffer);
        if (!color) { failed++; return; }
        await updateFn(item.id, color);
        updated++;
      })
    );
    processed += batch.length;
    console.log(`  ${label}: ${processed}/${items.length} processed, ${updated} updated, ${failed} failed`);
  }
}

async function main() {
  console.log("=== Backfill Dominant Colors ===\n");

  // Items with imageFilename but no dominantColor
  const { eq, and, isNotNull } = await import("drizzle-orm");

  const itemsToProcess = await db
    .select({ id: schema.items.id, imageFilename: schema.items.imageFilename })
    .from(schema.items)
    .where(and(isNotNull(schema.items.imageFilename), isNull(schema.items.dominantColor)));

  console.log(`Items: ${itemsToProcess.length} need processing`);
  await processBatch(
    itemsToProcess as { id: number; imageFilename: string }[],
    (item) => fetchFromS3(item.imageFilename),
    async (id, color) => {
      const { eq } = await import("drizzle-orm");
      await db.update(schema.items).set({ dominantColor: color }).where(eq(schema.items.id, id));
    },
    "Items",
  );

  // GlobalItems with imageSourceUrl (external URLs stored in S3)
  const globalWithFile = await db
    .select({ id: schema.globalItems.id, imageSourceUrl: schema.globalItems.imageSourceUrl })
    .from(schema.globalItems)
    .where(and(isNotNull(schema.globalItems.imageSourceUrl), isNull(schema.globalItems.dominantColor)));

  console.log(`\nGlobal Items (with source URL): ${globalWithFile.length} need processing`);
  await processBatch(
    globalWithFile as { id: number; imageSourceUrl: string }[],
    (item) => fetchFromUrl(item.imageSourceUrl),
    async (id, color) => {
      const { eq } = await import("drizzle-orm");
      await db.update(schema.globalItems).set({ dominantColor: color }).where(eq(schema.globalItems.id, id));
    },
    "Global Items",
  );

  // GlobalItems with imageUrl (direct URLs)
  const globalWithUrl = await db
    .select({ id: schema.globalItems.id, imageUrl: schema.globalItems.imageUrl })
    .from(schema.globalItems)
    .where(and(isNotNull(schema.globalItems.imageUrl), isNull(schema.globalItems.dominantColor)));

  console.log(`\nGlobal Items (with image URL): ${globalWithUrl.length} need processing`);
  await processBatch(
    globalWithUrl as { id: number; imageUrl: string }[],
    (item) => fetchFromUrl(item.imageUrl),
    async (id, color) => {
      const { eq } = await import("drizzle-orm");
      await db.update(schema.globalItems).set({ dominantColor: color }).where(eq(schema.globalItems.id, id));
    },
    "Global Items (URL)",
  );

  // Thread candidates
  const candidatesToProcess = await db
    .select({ id: schema.threadCandidates.id, imageFilename: schema.threadCandidates.imageFilename })
    .from(schema.threadCandidates)
    .where(and(isNotNull(schema.threadCandidates.imageFilename), isNull(schema.threadCandidates.dominantColor)));

  console.log(`\nCandidates: ${candidatesToProcess.length} need processing`);
  await processBatch(
    candidatesToProcess as { id: number; imageFilename: string }[],
    (item) => fetchFromS3(item.imageFilename),
    async (id, color) => {
      const { eq } = await import("drizzle-orm");
      await db.update(schema.threadCandidates).set({ dominantColor: color }).where(eq(schema.threadCandidates.id, id));
    },
    "Candidates",
  );

  console.log("\n=== Backfill Complete ===");
  process.exit(0);
}

main().catch((err) => {
  console.error("Backfill failed:", err);
  process.exit(1);
});
```

Note: The exact import patterns for drizzle-orm may need adjustment based on the project's existing database connection setup. Check `src/db/` for the actual connection pattern used and replicate it in the script.
</action>
<verify>
<automated>test -f scripts/backfill-dominant-colors.ts && grep "extractColor" scripts/backfill-dominant-colors.ts && grep "processBatch" scripts/backfill-dominant-colors.ts && echo "PASS" || echo "FAIL"</automated>
</verify>
<acceptance_criteria>
- `scripts/backfill-dominant-colors.ts` exists
- Script queries items, globalItems, threadCandidates with images but no dominantColor
- Processes in batches of 10 concurrent
- Extracts dominant color via Sharp resize(1,1)
- Updates database records with extracted color
- Skips records that already have dominantColor (idempotent)
- Logs progress: `Items: 45/123 processed, 42 updated, 3 failed`
- Handles errors gracefully (skips failed images, logs them)
- Exits with 0 on success, 1 on fatal error
</acceptance_criteria>
</task>

### Task 2: Add npm script for backfill
<task type="code">
<read_first>
- package.json
</read_first>
<action>
Add to `scripts` section in `package.json`:
```json
"backfill:colors": "bun run scripts/backfill-dominant-colors.ts"
```
</action>
<verify>
<automated>grep "backfill:colors" package.json && echo "PASS" || echo "FAIL"</automated>
</verify>
<acceptance_criteria>
- package.json contains `"backfill:colors"` script
- Script points to `scripts/backfill-dominant-colors.ts`
</acceptance_criteria>
</task>

</tasks>

<verification>
1. `bun run lint` passes (script follows project conventions)
2. Script is syntactically valid: `bun run scripts/backfill-dominant-colors.ts --help` or `bun check scripts/backfill-dominant-colors.ts`
3. Script handles missing S3 credentials gracefully (error message, not crash)
</verification>

<success_criteria>
- Backfill script exists and processes all 3 tables
- Script is idempotent (safe to re-run)
- Batch processing limits concurrency to 10
- Progress logging shows processing status
- npm script shortcut available
</success_criteria>

<threat_model>
| Threat | Severity | Mitigation |
|--------|----------|------------|
| S3 credential exposure in script | Low | Uses env vars from process.env, no hardcoded credentials |
| SSRF via globalItems imageUrl | Medium | Script only processes URLs already stored in the database (previously validated on ingestion); fetch has 10s timeout |
| Database overload from bulk updates | Low | Batch size of 10 limits concurrent DB writes |
</threat_model>

<must_haves>
- [ ] Backfill script at scripts/backfill-dominant-colors.ts
- [ ] Processes items, globalItems, threadCandidates
- [ ] Idempotent (skips existing dominantColor)
- [ ] Batch processing with concurrency limit
- [ ] Progress logging
- [ ] npm script shortcut
</must_haves>