fix: ignore hidden named source operands

docs/spec.md

@@ -319,6 +319,22 @@ ImportPath    = ident { "." ident } .
   delegated graph-import scan or tools. An ordinary build compares production
   names only; one test product compares its production, same-package test, and
   external-test selections without merging their units.
+- A single existing raw `.ww` operand is also subject to the unconditional
+  leading-name rule: if its final requested basename begins `.` or `_`, it is
+  ignored before the source is opened. Named raw sources otherwise retain their
+  existing all-files behavior, so a visible wrong-platform suffix remains
+  eligible. Only the requested basename participates: a hidden parent does not
+  hide visible `main.ww`, a hidden symlink spelling stays hidden for any
+  existing non-directory target, and a visible symlink spelling stays eligible.
+  The excluded operand creates no package, declaration, import binding/edge,
+  action, artifact, initialization, test,
+  publication, or persistent state. `ww build` reports the existing
+  `directory contains no WW package sources` condition; an explicit running
+  raw `ww test` also emits its command-owned `FAIL`, while `-c` and `-S` do not.
+  This rule does not add multiple named-source package support, does not change
+  visible `*_test.ww` handling, and does not apply to logical operands,
+  directory/recursive requests, imports, or `ww run`. The diagnostic parent is
+  presentation metadata and never canonical identity.
 - `import acme.codec;` loads the canonical package `acme.codec`. If that
   package declares `package wire;`, the importing file sees its exported names
   as `wire.Name`; `codec.Name` is not an additional binding. An explicit alias