A desktop client reading /api/software had no way to learn that a title costs
money. There was nothing in the response to say so, no way to sign in, and no
way to be told "you do not own this" — so a store with paid titles could only
hand the client a 403 at download time and let it guess why.
The fix belongs here rather than in the client. A client serves more than one
store, so anything it knows about a particular one has to arrive from that
store's own API; a rule compiled into the client is a rule that breaks every
other catalog it reads. Three seams, each following the storage adapter's
shape — documented contract, default that is byte for byte the old behaviour,
one config key to replace it:
- **access policy** — visible_software_scope / access_for / authorize_download.
Every catalog entry now carries an `access` block (gated, entitled, price,
purchaseUrl, webUrl) and both /api/download and /file/* ask before serving.
The vocabulary is deliberately generic: a word from one host's domain would
make every client that reads it specific to that host.
- **client sign-in** — the device authorization grant (RFC 8628), over the
host's own user model. The approval page stays the host's, because approving
needs a session and HTML. Tokens are ApplicationTokens with a `catalog`
scope, so publishing and reading stay separable.
- **service descriptor** — GET /api/service says what this deployment is and
whether it has a sign-in at all, which is how a client stops guessing.
With no policy and no subject class configured — every deployment today — the
API is unchanged: /api/auth/* answers 404, /api/service reports auth: null, and
the 187 pre-existing examples pass untouched.
A policy that raises is treated as a refusal, not permission. An artifact
served because the gatekeeper crashed is the one failure mode this must not
have, so a broken policy empties the catalog and denies the download.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>