Implement `notifications/src/delivery/telegram.ts` for Telegram alerts

[Levi-Ojukwu]

Description
Telegram is widely used by DeFi communities. A Telegram notification channel lets users receive invoice lifecycle alerts directly in their Telegram channels or DMs without setting up a webhook.

Requirements and context

• POST /subscriptions/telegram — register a Telegram bot token and chat ID
• Use the Telegram Bot API to send messages
• Message format: Markdown with key invoice details and a deep link to the dApp
• Support events: invoice.submitted, invoice.funded, invoice.paid, invoice.expiring_soon, invoice.disputed
• Write tests with mocked Telegram Bot API

Suggested execution

git checkout -b feat/notifications-telegram

• Implement in notifications/src/delivery/telegram.ts
• Create message templates
• Write tests

Example commit message
feat(notifications): add Telegram notification channel

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[GiftedGiftB]

@GiftedGiftB has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I can get this work done in less than 30 minutes.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @GiftedGiftB to this issue.

[Killerjunior]

@Killerjunior has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I have read and understood the issue requirements and checked the necessary documentation. I’m confident I can work on this task effectively and deliver a proper solution.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Killerjunior to this issue.

[neyij]

@neyij has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

hi, i would like to work on this.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @neyij to this issue.

[Ultra-Tech-code]

@Ultra-Tech-code has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

hello, I'd like to work on this issue.

I'll implement the Telegram notification delivery channel in notifications/src/delivery/telegram.ts. I'll add support for registering Telegram subscriptions through POST /subscriptions/telegram, integrate with the Telegram Bot API for sending alerts, create Markdown message templates with invoice details and dApp deep links, support the required invoice lifecycle events, and add tests using a mocked Telegram Bot API.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Ultra-Tech-code to this issue.

[thisstk]

@thisstk has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer can I work on this. I can get the issue solved under 20 minutes

ℹ️ Repo Maintainers: To accept this application, review their application or assign @thisstk to this issue.

[drips-wave]

Congratulations, @Ultra-Tech-code! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Ultra-Tech-code: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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[grantfox-oss]

🦊 GrantFox — @Ultra-Tech-code has been assigned to this issue!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #384)
2. Your PR will be reviewed by the Invoice-Liquidity-Network maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@Ultra-Tech-code's PR #392 was approved and merged by @Nursca.

🏆 @Ultra-Tech-code: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (751 total points). Track your full progress on GrantFox.

👏 Great work, @Ultra-Tech-code! Keep contributing to Invoice-Liquidity-Network.