linshenkx/prompt-optimizer · error · EvaluationValidationError

${label} #${index + 1} must not provide both assetId and b64

Error message

${label} #${index + 1} must not provide both assetId and b64.

What it means

The mirror of the previous rule: a media item must not supply both assetId and b64, because the service cannot decide which source of truth to use for the image. Validation throws when both fields are non-empty on the same item.

Source

Thrown at packages/core/src/services/evaluation/service.ts:1685

  private validateMediaItems(mediaItems: EvaluationMediaItem[], label: string): void {
    mediaItems.forEach((item, index) => {
      const itemLabel = item?.label?.trim() || '';
      const assetId = item?.assetId?.trim() || '';
      const b64 = item?.b64?.trim() || '';

      if (!itemLabel) {
        throw new EvaluationValidationError(`${label} #${index + 1} label must not be empty.`);
      }

      if (!assetId && !b64) {
        throw new EvaluationValidationError(
          `${label} #${index + 1} must provide either assetId or b64.`
        );
      }

      if (assetId && b64) {
        throw new EvaluationValidationError(
          `${label} #${index + 1} must not provide both assetId and b64.`
        );
      }
    });
  }

  private validateContentBlock(
    block: EvaluationContentBlock | undefined,
    label: string
  ): void {
    if (!block) {
      throw new EvaluationValidationError(`${label} must not be empty.`);
    }
    if (!block.label?.trim()) {
      throw new EvaluationValidationError(`${label} label must not be empty.`);
    }
    const hasContent = !!block.content?.trim();
    const hasMedia = this.hasBlockMedia(block);

View on GitHub (pinned to 3e677b1d9f)

Solutions

1. Keep exactly one of assetId or b64 on the media item and delete the other
2. Prefer assetId for large/stored images and b64 only for small inline payloads
3. Strip the unused field in a pre-submit sanitizer

Example fix

// before
media: [{ label: 'img', assetId: 'img-1', b64: base64String }]

// after
media: [{ label: 'img', assetId: 'img-1' }]

function pickOneSource(item: { label: string; assetId?: string; b64?: string }) {
  return item.assetId?.trim()
    ? { label: item.label, assetId: item.assetId }
    : { label: item.label, b64: item.b64 };
}
const sanitized = media.map(pickOneSource);

null

try {
  await evaluationService.create(request);
} catch (err) {
  if (err instanceof EvaluationValidationError && /must not provide both/.test(err.message)) {
    request = stripConflictingFields(request); // keep assetId, drop b64
  } else throw err;
}

When it happens

Trigger: A media item whose assetId and b64 are both non-empty strings. Typically introduced when code sets b64 as a default and then also assigns an assetId (or vice versa).

Common situations: Migrating from b64 to assetId-based flow without clearing the old field; spread-merging objects that accidentally combine both; form UI that populates both inputs.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• ${label} #${index + 1} label must not be empty.
• ${label} #${index + 1} must provide either assetId or b64.
• Result evaluation snapshot testCaseId must match testCase.id
• Image result evaluation requires at least one output image e
• Compare evaluation requires at least one test case.

AI-assisted analysis of linshenkx/prompt-optimizer@3e677b1d9f (2026-08-27). Data as JSON: /api/errors/3219ef89d51b45c0. Report an issue: GitHub.