Versioning

The REST API has a version named by a date. The current version is 2026-10-07.

Pin the version

Send the Passion-Version header to say which version your code expects:

curl https://api.passion.io/v1/apps/12345/overview \
  -H "Authorization: Bearer psn_key_…" \
  -H "Passion-Version: 2026-10-07"

• Every REST response has a Passion-Version header with the version it answers with.
• When you do not send the header, you get the current version.
• When you send a version that does not exist, the request is refused with 400 and the code unknown_version. The message names the current version.

What changes a version

• Additive changes keep the version. A new route, a new optional input field or a new field in a response does not change the date. Write your code so that it ignores fields it does not know.
• Breaking changes get a new date. Removing or renaming a field, or changing what a field means, gets a new version.

The MCP

The version header is for the REST API. MCP clients agree on the MCP protocol version when they connect; see MCP.