📝 Document the tagged-union matcher

backlog.tasks

@@ -46,6 +46,9 @@ Matcher:
     → the fallback is now a second argument: `(handlers, (s) => …)`, `s: Exclude<T, keyof handlers>`
 ✔ A fallback for an already-exhaustive handler map must be a compile error @medium @done
     → rejected by an F-bounded constraint on `Handled` (checked *after* inference); a conditional in the fallback parameter is evaluated too early and breaks contextual typing
+✔ 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
 
 Bugs:
 ✔ TS 7 LSP server logs `context canceled` on stderr at shutdown @done
@@ -55,6 +58,8 @@ Enhancements:
 ✔ Allow boolean literals in primitive union patterns (e.g. `true: () => "yes"`) @medium @done
     ✔ Are there other primitive types that should be supported in union patterns? (e.g. `bigint`, `symbol`) @medium @done
         → added boolean, null and undefined; rejected `symbol` (compile-time brand, nothing at runtime) and `bigint` (not a property key)
+☐ Allow boolean, null and undefined discriminant values in tagged-union patterns @medium
+    → needs the primitive matcher's `PatternKey` / `PatternParam` projection; see development/library.md § Tagged-union matcher
 
 Documentation:
 ☐ Bring README.md back to its previous form — synopsis and examples restored, in the correct place