Phase 1.1 of the work breakdown. The finding that shaped it came before
any code: **the control plane special-cases nothing.** provides,
requires, contributes and grants are entirely name-agnostic, so asking
for a bucket needed no change to the mesh at all — only a provider that
answers. What was missing was the last step, where something on the
machine turns a delivered secret into a key that works.
Named `s3-bucket` by ADR 0027's test: a consumer's code is written
against the S3 API, and swapping one store for another does not break
it, so the coupling is to the protocol rather than the product — which
is what the substrate design already said about AMQP, S3 and OCI.
Proven on a real store, 7 assertions: a generated secret becomes a
working key; rotation makes the new one work and the old one stop; a
consumer that goes away loses its key; a key nobody here made is left
alone; a manifest naming a credential that was never written is refused;
an unusable bucket name is refused naming the consumer that asked.
**And the one a database does not need.** One PostgreSQL server holds
separate databases and the product enforces the boundary; one object
store holds every bucket behind one endpoint, so a consumer being unable
to reach another's is a policy somebody wrote. A policy granting
arn:aws:s3:::* would pass every other test in the file, so the unit
tests assert what the policy does NOT say.
It drives the vendor's command line rather than an SDK: the admin API
encrypts its request bodies, which is why a separate admin library
exists, and pulling that in would add a system-metrics dependency tree
to a repository with none in order to create a user.
