Add Buf required annotations to standalone Nexus APIs

CONTRIBUTING.md

@@ -0,0 +1,14 @@
+# Contributing
+
+## Field validation
+
+Field constraints use standard [Buf Protovalidate annotations](buf/validate/validate.proto):
+
+```proto
+import "buf/validate/validate.proto";
+
+// Inside a message:
+string namespace = 1 [(buf.validate.field).required = true];
+```
+
+`required` rejects zero-valued ordinary proto3 scalars and empty lists/maps. Fields with explicit presence only require presence. Consuming applications enforce the annotations with Protovalidate. The upstream schema is vendored alongside the Google and Nexus dependencies and pinned in `buf.lock`.

README.md

@@ -8,6 +8,8 @@ Install as git submodule to the project.
 
 ## Contribution
 
+See [CONTRIBUTING.md](CONTRIBUTING.md) for field validation guidance.
+
 Make your change to the temporal/proto files, and run `make` to update the openapi definitions.
 Rust is also required because `make` installs and runs `nex-gen` when regenerating system Nexus WIT files.
 

buf.lock

@@ -1,6 +1,9 @@
 # Generated by buf. DO NOT EDIT.
 version: v2
 deps:
+  - name: buf.build/bufbuild/protovalidate
+    commit: 435963d1631043e694e56e6bcc3c79c3
+    digest: b5:f4ea07ad2dd94bd7243562f9908b9fb104feef8076040c89d9f7c1dedc074de4d4ce2b997686ef4400f3eccb765a7cfc20ed4acdd70b9a3699351245c61dba97
   - name: buf.build/googleapis/googleapis
     commit: 004180b77378443887d3b55cabc00384
     digest: b5:e8f475fe3330f31f5fd86ac689093bcd274e19611a09db91f41d637cb9197881ce89882b94d13a58738e53c91c6e4bae7dc1feba85f590164c975a89e25115dc

buf.yaml

@@ -6,7 +6,9 @@ modules:
       # Vendored for api-linter (can't read the BSR); excluded so buf sees them once.
       - google
       - nexusannotations
+      - buf
 deps:
+  - buf.build/bufbuild/protovalidate
   - buf.build/googleapis/googleapis
   - buf.build/temporalio/nexus-annotations
 lint: