build: omit named test source operands

docs/spec.md

@@ -326,15 +326,38 @@ ImportPath    = ident { "." ident } .
   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.
+  The prefix-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.
+- A visible single raw operand passed to `ww build` whose requested final
+  basename ends exactly `_test.ww` is test-only after its package clause and
+  contiguous initial import section have been read. Prefix exclusion remains
+  first, so a bare `_test.ww` is never opened. Header read, package-clause, and
+  initial-import syntax errors retain their ordinary precedence; after a valid
+  header the sole root is omitted. Its dotted imports are not resolved, and a
+  late import, body parse/type error, or runtime behavior is not observed. The
+  first ordinary body token is not lexed, so an immediately following malformed
+  UTF-8 byte or non-leading BOM is outside the header. A raw NUL reached while
+  locating that token and an unterminated comment in header trivia remain load
+  errors. Go's byte reader probes a following `i` as a possible `import`; the
+  corresponding WW boundary is the exact lexical `import` token, so an ordinary
+  WW identifier merely beginning with `i` is body syntax. This named-source
+  rule retains all-files platform behavior: a
+  visible `x_windows_test.ww` is still test-only. It classifies the requested
+  basename of a visible symlink, not its target name; a symlink whose target is
+  a directory remains a directory request.
+- Omission creates no canonical package, command-line package node, import
+  binding or edge, graph/action, symbol, initializer, executable, archive,
+  interface, publication, transaction, default `.sepwork`, or work-state
+  mutation. It does not alter `ww test`, `ww test -c`, `ww test -S`, logical
+  operands, directory/recursive selection, multiple named-source support,
+  imports, or `ww run`. Physical directory and symlink-target data remain
+  observation metadata, never package, import, graph, action, artifact,
+  symbol, `.wwi`, publication, or persistence identity. Build workdir format
+  remains 18, test workdir format remains 19, and semantic storage format
+  remains 3.
 - `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
@@ -467,6 +490,15 @@ ImportPath    = ident { "." ident } .
   Output paths and directory metadata never become package, import, graph, action,
   symbol, artifact, `.wwi`, or persistence identity.
 
+  A valid omitted single raw `*_test.ww` build has an empty selection. With no
+  effective `-o`, including an assembly-only request, and with exact
+  `-o /dev/null`, it succeeds silently. A non-directory effective output fails
+  with `ww: no packages to build`; an output-directory effective output fails
+  with `ww: no main packages to build`. These empty-selection outcomes occur
+  only after the raw test source's header has loaded successfully, create no
+  output path or parent, and preserve every pre-existing output and work-state
+  byte unchanged.
+
   Every caller-visible build installation checks its destination after all
   applicable compile, assemble, archive, and link producers finish. Ordinary
   `stat` follows symlinks. An existing directory rejects as