docs: scope AGENTS instructions by directory (#2083)

crates/kms/AGENTS.md

@@ -0,0 +1,27 @@
+# KMS Crate Instructions
+
+Applies to `crates/kms/`.
+
+## Change Coordination
+
+When changing key-management behavior, verify compatibility with:
+
+- `rustfs/src/storage/ecfs.rs`
+- `rustfs/src/admin/handlers/kms.rs`
+- `rustfs/src/admin/handlers/kms_dynamic.rs`
+- `rustfs/src/admin/handlers/kms_keys.rs`
+- `rustfs/src/admin/handlers/kms_management.rs`
+
+## Security
+
+- Never log plaintext keys, key material, or sensitive request payloads.
+- Prefer explicit error propagation over panic paths.
+
+## Testing
+
+For local KMS end-to-end tests, keep proxy bypass settings:
+
+```bash
+NO_PROXY=127.0.0.1,localhost HTTP_PROXY= HTTPS_PROXY= http_proxy= https_proxy= \
+cargo test --package e2e_test test_local_kms_end_to_end -- --nocapture --test-threads=1
+```