Lossy protocol conversions

Any shipped inbound protocol can reach any shipped outbound protocol. That pivot is not always lossless. The cases below are known; claiming fidelity outside this list is how a bridge gets trusted more than it deserves.

Same-protocol requests keep provider field shapes. Cross-protocol requests translate through a shared request shape, request, response, and stream chunks, and only the fields both wires can express survive.

What it looks like

An OpenAI client can call acme/claude even when that alias resolves to Anthropic. The caller keeps speaking chat completions (or responses); the gateway translates. Worked examples are on Calling the gateway.

await client.chat.completions.create({
  model: "acme/claude",
  messages: [{ role: "user", content: "Say hello" }],
})

await client.messages.create({
  model: "acme/gpt",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Say hello" }],
})

await client.models.generateContent({
  model: "acme/gpt",
  contents: "Say hello",
})

curl https://<app>.gw.ourseams.com/v1/chat/completions \
  -H "Authorization: Bearer ak_acme_…" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "acme/claude",
    "messages": [{ "role": "user", "content": "Say hello" }]
  }'

Known losses