[WIP] Fix fail-closed logic in isDisposable function

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Improvement 2: The "Fail-Closed" Logic
The Flaw: In your D1 isDisposable function, you have if (!activeTableResult) { return false; }. This is a "fail open" scenario. If your state table fails to read, you return false (meaning "not disposable"), and a disposable email is marked as isValid: true. This is a critical bug.

The "Pro" Fix: We must "fail closed". If anything goes wrong in the check, we must assume the email is disposable to protect your customer.

Action: My new isDisposable function from Improvement 1 already fixes this by having a safe default. But to make your original D1 code safer, the fix would be:

TypeScript

// In your original D1-only code...
if (!activeTableResult) {
console.error("CRITICAL: active_table not found or uninitialized.");
return true; // <-- FAIL CLOSED. Assume disposable if state is broken.
}

Improvement 3: The "Bulletproof" Cron Safety Check
The Flaw: Your safety check in handleScheduled is if (domains.length < 100000). This is good. I am glad you have this. But it's brittle. What if the list shrinks to 99,000 domains? Your cron will fail forever.

The "Pro" Fix: Use a more reasonable threshold to only check for catastrophic failure (e.g., the source URL returning 0 results).

Action:

TypeScript

// myprojectsravi/email_validation_api/myProjectsRavi-email_validation_api-990fb5cbb616a226739b939d82af1c8e240d200a/src/index.ts

// ... inside handleScheduled ...
if (domains.length < 50000) { // Safety check
console.error(Fetched list is too small (${domains.length}). Aborting update to prevent data loss.);
return;
}

The Flaw: Your API (...990fb5c) makes two D1 reads for every single validation request. Look at your isDisposable function:

D1 Read 1: SELECT live_table FROM active_table... (To find out if we should use "blue" or "green")

D1 Read 2: SELECT domain FROM disposable_domains_blue... (To actually check the domain)

This is an unnecessary double-dip. We are storing the state (the pointer) in the same place as the data (the domains). We can make this faster.

The "God Mode" Solution: The data (millions of domains) belongs in D1. The state (a single string: "blue" or "green") belongs in KV.

By combining D1 and KV, we use each for its perfect job. This removes a D1 query from every API call, making your API even faster and more efficient.

Here are the exact changes to make your API truly "god-mode."

1. New wrangler.toml
   We need to re-introduce a KV binding, but only for storing the state.

Ini, TOML

name = "email-validation-api"
main = "src/index.ts"
compatibility_date = "2025-10-31"

[handlers]
fetch = "fetch"
scheduled = "scheduled"

1. The DATA (Millions of domains)

[[d1_databases]]
binding = "DB"
database_name = "email-validation-db"
database_id = "<YOUR_D1_DATABASE_ID_GOES_HERE>"

2. The STATE (A single key: 'live_table' = 'blue' or 'green')

[[kv_namespaces]]
binding = "API_STATE"
id = "<YOUR_NEW_KV_NAMESPACE_ID>"
preview_id = "<YOUR_NEW_KV_PREVIEW_ID>"

[triggers]
crons = ["0 0 * * 0"]
2. Updated schema.sql
We no longer need the active_table in D1. KV is handling that.

SQL

-- schema.sql
DROP TABLE IF EXISTS disposable_domains_blue;
CREATE TABLE disposable_domains_blue (
domain TEXT PRIMARY KEY NOT NULL
);

DROP TABLE IF EXISTS disposable_domains_green;
CREATE TABLE disposable_domains_green (
domain TEXT PRIMARY KEY NOT NULL
);

-- The 'active_table' is NO LONGER NEEDED.
-- We will store this pointer in a KV binding named 'API_STATE'
After you run this, you must manually seed your KV namespace one time: wrangler kv:key put --binding=API_STATE "live_table" "blue"

3. Updated src/index.ts (The Final Code)
   This code is now faster, cleaner, and uses the best of both worlds.

TypeScript

// src/index.ts
import { Hono } from 'hono';

// === TYPE DEFINITIONS ===

export interface Env {
DB: D1Database;
API_STATE: KVNamespace; // <-- The state pointer
}

// (DnsQueryResponse and ValidationResult are unchanged)
interface DnsQueryResponse {
Status: number;
Answer?: { type: number; data: string }[];
}
interface ValidationResult {
email: string;
isValid: boolean;
reason: 'valid' | 'invalid_syntax' | 'disposable' | 'no_mx_record';
checks: {
syntax: boolean;
disposable: boolean;
mx_record: boolean;
};
}

// === CONFIGURATION ===

const DISPOSABLE_LIST_URL = 'https://raw.githubusercontent.com/disposable-email-domains/disposable-email-domains/master/list.txt';

// === VALIDATION HELPERS ===

function isEmailSyntaxValid(email: string): boolean {
const emailRegex = /^[a-zA-Z0-9.!#$%&'+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:.[a-zA-Z0-9-]+)$/;
return emailRegex.test(email);
}

/**

• [Check 2] High-speed disposable domain check.
• This is now the "God Mode" version.
• 1. Read the 'live_table' pointer from KV (fastest read)
• 2. Query that D1 table.
• This is now ONE KV read and ONE D1 read, not two D1 reads.
  */
  async function isDisposable(domain: string, env: Env): Promise {
  // 1. Get pointer from KV
  const live...

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