One reading answered three ways, holding nothing and touching no context's
store — which is the constraint the whole document is about, and the thing the
board being replaced gets wrong.
A page nobody had thought to ask for turns out to be the one a person
opens first: what is not doing what it was told. Recorded with the order
that matters — broken, then quiet, then out of date — because a page
leading with the last would bury the first.
And refused stays distinct from failed all the way to the page. They are
fixed in different places, so one word for both sends half its readers to
the wrong one.
Two additions to the module-repository design, both from building it.
A build machine has its own credential and it is not a node's: read the
build queue, write the mesh exchange, nothing else. A node's queue
carries that node's declarations.
The answer goes through the exchange and never the default one, because
permission there is per exchange rather than per queue — anything allowed
to use it can publish into any node's queue. The price is that every
asker sees every result and filters by correlation, which is cheap
against a builder never needing that permission.
And every result is kept, failures included, because one that leaves no
trace is indistinguishable from a build nobody asked for. That is what a
builds view reads; the board page is corrected to say so.
A build is work, not state, and that is why it does not travel as a
declaration: as one it would either rebuild on every reconcile or carry
"and I already did this", which is state about an event rather than about
a machine. So it has its own queue and the answer comes back correlated.
Three properties recorded because they are decisions: acknowledge only
once the answer is away, one build at a time, and a failure is a result
rather than silence.
And the board page is corrected. A build result today is answered to
whoever asked and kept nowhere, so a builds view has nothing to read. A
record of past builds is the missing piece, not the builder.
Read from the board that exists. Eight sections; four are about work and
workers and are held back with that domain. The other four are the mesh
itself, and everything behind the main one already exists here — it is a
reader, not a second source of truth.
The constraint is the point of writing this down now. The existing board
is one service that reads every context's database, because that is the
shortest path to a page showing all of them at once. That is ADR 0008
violated by the one component with a reason to violate it, and the cost
is the same one the shared library has: a boundary nothing may cross is a
boundary that can move, and one thing crossing it is enough to freeze it.
So a board reads through interfaces and stores nothing. If a question is
slow, the answer belongs in the context that owns it, where everything
else asking gets it too.
jschoubben