test: accept empty skip reasons

docs/spec.md

@@ -930,6 +930,22 @@ and accounting in its product-local capture; a retained binary invoked directly
 keeps the warning on standard error, its accounting on standard output, and has
 no coordinator package result.
 
+Calling `test.skip(reason)` from an active test records a successful skip and
+stops that test body. The empty string is a valid reason: `test.skip("")` is
+not a malformed harness result. Its ordinary result line is exactly the
+qualified test name, ` ... SKIP: `, and a newline, with no reason bytes after
+the space. It increments skipped accounting once, increments neither failed nor
+harness-error accounting, and permits later selected tests to run. The same
+classification applies to raw single-file, same-package, external-package, and
+honest test-only descriptors; an active-test call reached through production
+package code; filtered execution; a coordinator-run retained binary; and later
+direct execution of a retained binary. Production files do not acquire a test
+descriptor. A nonempty reason keeps the same presentation with its bytes after
+`SKIP: `. An oversized reason remains an invalid control result, and
+`test.skip` outside an active test still aborts. This result rule does not
+change the current per-test process boundary, list mode, filtering language,
+package initialization, or package/import/action identity.
+
 After those ordered results, an ordinary explicit `ww test` request that records
 an attributable setup, build, or execution failure emits exactly one standalone
 `FAIL\n` on standard output. The line is command-owned: it follows even a later