Function isSpamComment

scripts/delete_spam_comments.ts:70–113

(body: string)

 * override or escape the system instructions.
 */
export async function isSpamComment(body: string): Promise<SpamCheckResult> {
  if (!body.trim()) {
    return { isSpam: false, reason: "Empty comment", confidence: 0 };
  }

  const client = createBedrockClient();

  // Sanitize and isolate the comment — never interpolate into the system prompt.
  const safeBody = sanitizeCommentBody(body);

  try {
    const responseBody = await retryWithBackoff(async () => {
      const command = new InvokeModelCommand({
        modelId: BEDROCK_MODEL_ID,
        contentType: "application/json",
        accept: "application/json",
        body: JSON.stringify({
          anthropic_version: "bedrock-2023-05-31",
          max_tokens: 256,
          temperature: 0.1,
          system: SPAM_DETECTION_PROMPT,
          // Comment is the sole user message — structurally isolated from instructions.
          messages: [{ role: "user", content: safeBody }],
        }),
      });
      const response = await client.send(command);
      return new TextDecoder().decode(response.body);
    });

    const parsed = JSON.parse(responseBody);
    const text = parsed.content?.find((c: any) => c.type === "text")?.text ?? "";
    const jsonMatch = text.match(/\{[\s\S]*\}/);
    if (!jsonMatch) throw new Error("No JSON in Bedrock response");

    const result = JSON.parse(jsonMatch[0]);
    const confidence = result.confidence ?? 0;
    const isSpam = result.is_spam === true && confidence >= CONFIDENCE_THRESHOLD;

    return { isSpam, reason: result.reason ?? "", confidence };
  } catch (err) {
    console.warn("Bedrock spam check failed, skipping:", err);
    return { isSpam: false, reason: "Bedrock check failed", confidence: 0 };
  }
}

/**
 * Run a second independent Bedrock call to confirm a spam verdict.