diff --git a/backlog.tasks b/backlog.tasks
index 055b79e..dc6eff8 100644
--- a/backlog.tasks
+++ b/backlog.tasks
@@ -51,6 +51,10 @@ Matcher:
 ✔ Implement matcher with similar API like matcher from primitive.ts @high @done
     → `getTaggedUnionMatcher` / `getTaggedUnionMatcherW`, curried on the discriminant key
     → fallback is the second argument; `_` removed
+☐ Rename `primitive` to `primitive-union` and `getMatcher` to `getPrimitiveMatcher` @medium
+    → `src/primitive.ts` / `src/primitive.test.ts` → `primitive-union.*`
+    → `getMatcherW` → `getPrimitiveMatcherW` for symmetry with the tagged-union pair
+    → update `src/index.ts`, `development/library.md` and any README references
 
 Bugs:
 ✔ TS 7 LSP server logs `context canceled` on stderr at shutdown @done