📝 Check off the LSP shutdown bug

Record the cause (Session.updateWatches raced against exit) and the
stdin-EOF fix now that npm run verify is green with no context-canceled
output.

backlog.tasks

@@ -48,7 +48,9 @@ Matcher:
     → `{ a, b, _ }` for `T = "a" | "b"` is accepted today; the redundant `_` should be rejected
 
 Bugs:
-
+✔ TS 7 LSP server logs `context canceled` on stderr at shutdown @done
+    → `handleExit` returns `io.EOF`, cancelling the background context while `Session.updateWatches` is still in flight; the bare error is flushed to stderr and the server exits 1
+    → close stdin after `shutdown` instead of sending `exit`; the server exits cleanly (code 0, no output), kill kept as a fallback
 Enhancements:
 ☐ Allow boolean literals in primitive union patterns (e.g. `true: () => "yes"`) @medium
 ☐ Are there other primitive types that should be supported in union patterns? (e.g. `bigint`, `symbol`) @medium