2026-09-05 10:27:11 +00:00
1 changed files with 41 additions and 0 deletions
@@ -96,6 +96,47 @@ grants clients, a mail server grants mailboxes. It is a facet, not a kind.
 **A module may also declare what it claims**, because some things cannot coexist and that is a
 fact about the module rather than about a particular node. What that means precisely is below.

+### Where the answer to a requirement is allowed to live
+
+*Written 2026-08-29, from building it. The table above distinguishes **presence** from
+**instantiation** and this is the half of that distinction nobody had noticed was missing: not
+what the edge hands over, but **where the thing on the other end is.***
+
+Two different things were both being written as a requirement:
+
+| | *a shell*, *a display server*, *a private network* | *a database*, *an object store*, *an identity provider* |
+|---|---|---|
+| where the answer lives | **this machine** | **somewhere in the mesh** |
+| how it is answered | install another module here | find the node already running it |
+| what is missing if absent | a module to assign here | **a decision about where**, which is nobody's to make silently |
+
+Answering the second like the first installs a database on every machine that uses one, which is
+what it did.
+
+**So a provided name carries a scope**, the same idea a claim already has, and written short in
+the ordinary case so the few that are not node-scoped stand out rather than drowning. Scope is a
+property of **the name, not of each provider**: two modules disagreeing about whether a database
+is local would make one requirement mean two things depending on which happened to answer it, so
+that is refused.
+
+**A requirement answered from the mesh is never satisfied by installing it here.** Nothing, and
+the mesh refuses and says which module to assign somewhere. Two, and it refuses and says how to
+choose — the same rule as everywhere else, for the same reason: picking is guessing, and the wrong
+guess puts somebody's data on a machine they did not choose.
+
+**Choosing is recorded per node**, because that is the granularity the choice actually has — two
+machines may reasonably use two different databases and a mesh-wide answer could not say so. A
+choice pointing at a machine that does not provide the thing is refused rather than quietly
+replaced by one that does, and a single available provider does not override a choice either.
+**Both are the same rule: the mesh does not overrule a person, and it does not move data without
+being told to.**
+
+**What this is a prerequisite for.** Knowing *which node* answers is the first half of handing a
+credential back — you cannot be given a database's password before it is settled whose database it
+is. So a node's resolution now records what it takes from elsewhere, which is both the only part
+of its set that stops working when a *different* machine goes away, and the place a credential
+will hang.
+
 ### An edge has two directions, and only one of them is built

 *Written 2026-08-29, from building it. The row above already says a consumer **supplies a target