# Swap an SDK at every call site behind an existing interface

One SDK replaced with another behind an interface that already exists, verified by the same interface tests.

Category: Vendor and third-party migrations
Source: https://letsship.ai/use-cases/swap-an-sdk-behind-an-interface
Published: 2026-08-25

## Goal

Replace an SDK with an alternative behind the existing interface.

## Acceptance criteria

- The same interface tests pass against the new implementation
- No caller imports the SDK directly
- The old dependency is removed
- Behaviour the new SDK cannot match is raised rather than silently dropped

## What lands as proof

An unchanged interface test suite passing against the new implementation.

## Prompt

Copy this to an agent to open the ticket:

```text
Create a Linear issue in my team and assign it to the SHIP agent.

Title: Swap {old} for {new}

Description: Replace an SDK with an alternative behind the existing interface.

Acceptance criteria:
- The same interface tests pass against the new implementation
- No caller imports the SDK directly
- The old dependency is removed
- Behaviour the new SDK cannot match is raised rather than silently dropped

Before you create the issue, confirm this repository already has an interface in front of the SDK. If it does not, that seam is a prerequisite ticket.
```

## Questions

### What does the agent actually change?

The ticket is scoped to one outcome: replace an SDK with an alternative behind the existing interface. Work that serves that outcome is in scope, and anything outside it is left for a separate ticket, so the pull request stays reviewable.

### How do I know the work is done?

The pull request carries the evidence, not only the diff. Here that means the same interface tests pass against the new implementation, so a reviewer can confirm the result without reproducing the work locally.

### How much oversight does this need?

The run stops once the plan is written. Somebody reads the approach and approves it before any code exists, which is the cheapest moment to redirect the work.