diff --git a/CONVENTIONS.md b/CONVENTIONS.md
index ce4406a..090b51e 100644
--- a/CONVENTIONS.md
+++ b/CONVENTIONS.md
@@ -2,8 +2,20 @@
 
 ## Language & Dependencies
 
-- Go standard library only — no external dependencies.
 - Target the latest stable Go release.
+- Prefer Go standard library; approved third-party packages allowed (see below).
+
+### Approved Third-Party Packages
+
+| Package | Use Case | Notes |
+|---------|----------|-------|
+| `gopkg.in/yaml.v3` | YAML parsing | Persona files, config |
+| `github.com/google/go-cmp` | Test comparisons | `cmp.Diff` for readable diffs |
+
+To add a new dependency:
+1. Open a PR with justification (why stdlib is insufficient)
+2. Package must be well-maintained, widely used, minimal transitive deps
+3. Update this table when approved
 
 ## Error Handling