Issue 163 (was 161): another record took 161 on main first

ADR 0110 decided each assignment records where its requirements are answered
from; the control plane keeps only a per-machine pin (none recorded) and
resolves every requirement implicitly. Harmless with one provider; a second
one silently moves consumers' data.

04-ISSUES/163-an-assignment-does-not-record-which-provider-answers-it/00-report.md

@@ -0,0 +1,63 @@
+---
+status: open
+opened: 2026-09-30
+located-in:
+  - mesh-controller cmd/mesh-controller/modules.go (assign takes no provider; pin is a separate, per-machine command)
+  - mesh-controller internal/inventory (provision_pin keyed by (node, name))
+fixed-by:
+amended-design:
+---
+
+# 163 — An assignment does not record which provider answers it
+
+## What was observed
+
+Planning ace's modules that need a database (baserow, letta, n8n, and the apps using ace's
+predecessor postgres). The operator's model — and ADR 0110's — is that **an assignment states where
+each of its requirements is answered from**: gitea's assignment on novox says its `postgres-database`
+comes from novox; an app assigned to ace says whether its database comes from ace or from novox.
+
+The mesh holds no such statement for any assignment. Read on novox (2026-09-30):
+
+```
+select … from provision_pin;   -- 0 rows
+```
+
+Every requirement in the mesh resolves implicitly, each time, by ADR 0084's order (a pin, then the
+provider on the consumer's own node, then the only provider).
+
+## What was decided, and what exists
+
+[ADR 0110](../../02-DECISIONS/0110-a-seat-is-a-module-assignment-from-a-closed-set.md):
+
+> Where several remain and none is local, **a person chooses when the module is assigned**.
+> Assignment lists the candidates, with the holder of a seat that delivers the provision suggested
+> first, and records the answer on the assignment as its pin. Without an answer the module is not
+> assigned.
+
+What the control plane implements:
+
+| decided | implemented |
+|---|---|
+| the answer is recorded **on the assignment** | `provision_pin` is keyed `(node, name)` — one answer per machine per provision, shared by every module on it |
+| chosen **at assignment** | `assign <node> <module>` takes no provider; `pin <node> <provision> <from-node>` is a separate command |
+| an assignment may be answered from its own machine (gitea ← novox) | `pin` refuses a machine pinning to itself ("does not need saying") |
+| every assignment has an answer | none recorded; resolution guesses the same answer every time |
+
+## Consequence
+
+Nothing is wrong *today* — with one postgres provider, every guess is the intended answer. But the
+answer is not a fact anyone stated, so:
+
+- **it changes silently** the day a second provider appears (e.g. a postgres assigned on ace): every
+  unpinned consumer re-resolves — a consumer on ace moves from novox's database to an empty one on ace
+  at the next push, which is data a module stops seeing without anything saying so;
+- two modules on one machine cannot take one provision from different providers;
+- a person reading an assignment cannot see where its data lives.
+
+## What would be right
+
+ADR 0110 as written: `assign` records, per requirement, the node that answers it (its own node
+included), offering the candidates and refusing an assignment without an answer where several exist;
+the per-machine `provision_pin` becomes a per-assignment record, with existing assignments backfilled
+from what they resolve to now so nothing moves.