test: prove declared package import semantics

docs/spec.md

@@ -249,13 +249,25 @@ PackageClause = "package" ident ";" .
 ImportDecl    = "import" ident ";" .
 ```
 
-- Every source file begins with a package clause. A directory of `.ww`
-  files sharing one package name compiles as a single module.
-- `import foo;` makes module `foo`'s exported names available as
-  `foo.Name`. Self-import is rejected.
-- An executable's entry module is `package main;` with a `fn main`.
+- Every source file begins with a package clause. A directory of eligible
+  `.ww` files sharing one declared package name compiles as one package. The
+  declared name need not equal the directory name or the final component of its
+  canonical import 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. The import binding
+  is scoped to that source file. A sibling file must declare its own import.
+  The package dependency graph is the sorted, deduplicated union of the real
+  imports in all eligible files. Self-import is rejected.
+- An executable package is one declared `package main` and containing a
+  `fn main`; path and directory spelling do not classify commands. An ordinary
+  import of a package declared `main` is rejected, except for the toolchain's
+  colocated external-test wiring.
 - Only names marked `export` (§5) are visible across module boundaries.
 
+The implemented grammar remains dotted and unaliased. Quoted import paths,
+explicit aliases, dot imports, and blank imports are not currently accepted.
+
 ---
 
 ## 5. Declarations