Update documentation

docs/policy/development.md

@@ -70,6 +70,32 @@ Use fixtures, local test servers, and package-level tests.
 - Prefer explicit registries and small package-level constructors over hidden
   global behavior.
 
+## Architecture-Preserving Changes
+
+When changing `weatherfeeder`, preserve the split between feedkit
+infrastructure and weather-domain behavior.
+
+Do:
+
+- keep generic scheduling, dispatch, processor, config, and sink mechanics in
+  feedkit;
+- keep weather provider rules in source adapters, provider helpers, and
+  normalizers;
+- keep canonical weather payloads in `model` and schema/wire identifiers in
+  `standards`;
+- keep Postgres table and row mapping under `internal/sinks/postgres`;
+- use explicit registries for built-in sources and normalizers.
+
+Do not:
+
+- move provider parsing, WMO mapping, or canonical weather policy into
+  `cmd/weatherfeeder`;
+- move weather-specific constants, schemas, or validation rules into feedkit;
+- put database column metadata or sink-specific tags on canonical model structs;
+- replace explicit registries with dynamic plugin loading;
+- introduce broad abstractions when a small provider-specific helper preserves
+  clarity.
+
 ## Dependency Policy
 
 Prefer the Go standard library unless a dependency materially improves