mistral-upgrade-migration

What this skill does

# Mistral AI Upgrade & Migration

## Current State

!`npm list @mistralai/mistralai 2>/dev/null || echo 'not installed'`
!`pip show mistralai 2>/dev/null | grep -E "^(Name|Version)" || echo 'not installed'`

## Overview

Guide for upgrading the Mistral AI SDK between major versions. The TypeScript SDK (`@mistralai/mistralai`) moved from CommonJS to ESM-only in v1.x, with significant API surface changes. This skill covers version detection, breaking change migration, automated code transforms, and rollback.

## Prerequisites

- Current Mistral AI SDK installed
- Git for version control
- Test suite available

## Instructions

### Step 1: Check Versions

```bash
set -euo pipefail
# Current version
npm list @mistralai/mistralai 2>/dev/null

# Latest available
npm view @mistralai/mistralai version

# All versions
npm view @mistralai/mistralai versions --json | jq '.[-5:]'

# Python
pip show mistralai 2>/dev/null | grep Version
```

### Step 2: Known Breaking Changes (v0.x to v1.x)

| Change | v0.x (old) | v1.x (current) |
|--------|-----------|----------------|
| Module format | CommonJS + ESM | **ESM only** |
| Import | `import MistralClient from '...'` | `import { Mistral } from '...'` |
| Constructor | `new MistralClient(apiKey)` | `new Mistral({ apiKey })` |
| Chat method | `client.chat(params)` | `client.chat.complete(params)` |
| Streaming | `client.chatStream(params)` | `client.chat.stream(params)` |
| Stream events | `for await (const chunk of stream)` | `for await (const event of stream)` access `.data` |
| Embeddings | `client.embeddings(params)` | `client.embeddings.create(params)` |
| Response types | Longer names | Shorter type names |
| Enum values | String constants | Forward-compatible unions |

### Step 3: Automated Migration Script

```typescript
// scripts/migrate-mistral-v1.ts
import { readFileSync, writeFileSync } from 'fs';
import { glob } from 'glob';

const TRANSFORMS = [
  // Import statement
  {
    find: /import\s+MistralClient\s+from\s+['"]@mistralai\/mistralai['"]/g,
    replace: "import { Mistral } from '@mistralai/mistralai'",
  },
  // Constructor
  {
    find: /new\s+MistralClient\((\w+)\)/g,
    replace: 'new Mistral({ apiKey: $1 })',
  },
  // Chat method (careful: only top-level .chat(), not .chat.complete())
  {
    find: /\.chat\((?!\.)/g,
    replace: '.chat.complete(',
  },
  // Streaming
  {
    find: /\.chatStream\(/g,
    replace: '.chat.stream(',
  },
  // Embeddings
  {
    find: /\.embeddings\((?!\.)/g,
    replace: '.embeddings.create(',
  },
];

async function migrate() {
  const files = await glob('src/**/*.{ts,js}');
  let totalChanges = 0;

  for (const file of files) {
    let content = readFileSync(file, 'utf-8');
    let changes = 0;

    for (const { find, replace } of TRANSFORMS) {
      const newContent = content.replace(find, replace);
      if (newContent !== content) {
        changes++;
        content = newContent;
      }
    }

    if (changes > 0) {
      writeFileSync(file, content);
      console.log(`Migrated: ${file} (${changes} changes)`);
      totalChanges += changes;
    }
  }

  console.log(`\nTotal: ${totalChanges} changes across ${files.length} files`);
}

migrate();
```

### Step 4: Upgrade Procedure

```bash
set -euo pipefail
# Create branch
git checkout -b upgrade/mistral-sdk-v1

# Backup lock file
cp package-lock.json package-lock.json.bak

# Upgrade
npm install @mistralai/mistralai@latest

# Ensure package.json has "type": "module"
node -e "const p=require('./package.json'); if(p.type!=='module') console.warn('WARNING: Add \"type\": \"module\" to package.json for ESM')"

# Run migration script
npx tsx scripts/migrate-mistral-v1.ts

# Verify
npm run typecheck
npm test
```

### Step 5: Model Name Updates

Model names change over time. Update hardcoded references:

```typescript
// Model alias mapping — update when models deprecate
const MODEL_ALIASES: Record<string, string> = {
  // Deprecated → Current
  'mistral-tiny': 'mistral-small-latest',
  'mistral-medium': 'mistral-small-latest', // Deprecated Q1 2025
  'open-mistral-7b': 'mistral-small-latest',
  'open-mixtral-8x7b': 'mistral-small-latest',

  // Current (no change needed)
  'mistral-small-latest': 'mistral-small-latest',
  'mistral-large-latest': 'mistral-large-latest',
  'codestral-latest': 'codestral-latest',
  'mistral-embed': 'mistral-embed',
};

function resolveModel(model: string): string {
  const resolved = MODEL_ALIASES[model];
  if (resolved && resolved !== model) {
    console.warn(`Model "${model}" is deprecated, using "${resolved}"`);
  }
  return resolved ?? model;
}
```

### Step 6: Validation Tests

```typescript
import { describe, it, expect } from 'vitest';
import { Mistral } from '@mistralai/mistralai';

describe('SDK Upgrade Validation', () => {
  it('should import Mistral correctly', () => {
    expect(Mistral).toBeDefined();
    expect(typeof Mistral).toBe('function');
  });

  it('should construct client', () => {
    const client = new Mistral({ apiKey: 'test-key' });
    expect(client.chat).toBeDefined();
    expect(client.chat.complete).toBeDefined();
    expect(client.chat.stream).toBeDefined();
    expect(client.embeddings).toBeDefined();
    expect(client.embeddings.create).toBeDefined();
    expect(client.models).toBeDefined();
    expect(client.models.list).toBeDefined();
  });
});
```

### Step 7: Rollback

```bash
set -euo pipefail
# Quick rollback
npm install @mistralai/[email protected] --save-exact
git checkout -- src/  # Restore pre-migration code
npm test

# Or just revert the branch
git checkout main
git branch -D upgrade/mistral-sdk-v1
```

## Error Handling

| Error After Upgrade | Cause | Solution |
|---------------------|-------|----------|
| `ERR_REQUIRE_ESM` | Missing "type": "module" | Add to package.json |
| `Mistral is not a constructor` | Old import style | Use `import { Mistral }` |
| `.chat is not a function` | Old method call | Use `.chat.complete()` |
| Type errors | Interface changes | Update types to match v1.x |
| Test failures | Response shape changed | Update assertions and mocks |

## Resources

- [TypeScript SDK Releases](https://github.com/mistralai/client-ts/releases)
- [Python SDK Releases](https://github.com/mistralai/client-python/releases)
- [Changelog](https://docs.mistral.ai/getting-started/changelog/)
- [Models Deprecation](https://docs.mistral.ai/getting-started/models/)

## Output

- Updated SDK to latest version
- Automated code migration applied
- Model name references updated
- Test suite passing after upgrade
- Rollback procedure documented