Sarvam TTS engine is broken: `default` export is undefined, constructor is `SarvamAIClient`

[shreyaskarnik]

Found by @Joilence during review of #36. Pre-existing on main, unrelated to that PR's packaging work.

The bug

src/tts/engines/sarvam.ts destructures the default export:

({ default: SarvamAI } = await import('sarvamai'));
// ...
const client = new SarvamAI({ apiSubscriptionKey: this.resolveApiKey() });

sarvamai@1.1.8 has no default export, and SarvamAI is a namespace object, not a constructor. The client class is exported as SarvamAIClient:

$ node --input-type=module -e "const m = await import('sarvamai'); \
    console.log('default:', typeof m.default); \
    console.log('SarvamAI:', typeof m.SarvamAI); \
    console.log('SarvamAIClient:', typeof m.SarvamAIClient)"

default:         undefined
SarvamAI:        object
SarvamAIClient:  function

So new SarvamAI(...) throws SarvamAI is not a constructor for every user who has the package correctly installed. The engine has never worked.

Why it went unnoticed

The try/catch around the import only wraps the import() itself, and reports any failure as "requires the 'sarvamai' package". The new call is outside it, so the actual failure is a bare TypeError at a line that looks unrelated to the import. Nothing in the suite covers it — sarvamai isn't installed on main, so there's no test that could have caught it.

Fix

Destructure the named export instead:

const { SarvamAIClient } = await import('sarvamai');
const client = new SarvamAIClient({ apiSubscriptionKey: this.resolveApiKey() });

Not yet verified

Whether the convert() call underneath is also wrong — that needs a live Sarvam API key to exercise. The constructor fix is necessary but may not be sufficient.

Once #36 lands, sarvamai becomes a devDependency and is mockable, so this should ship with a test asserting the client is constructed and convert() receives the expected payload — the same shape as tests/tts/mlx-audio.test.ts.