CANP-WP-0002 T02: registry-scoped identity and namespace ownership

Section 17 already defined what a registry does when the same id@version is
republished; nothing defined what a *consumer* does. That is where namespace
conflict actually bites — in the catalog, after installing from two
registries.

Identity is now registry-scoped: an id names a package within a registry, the
way a path names a file within a repository. A local-first format with no
signing, no federation and no central authority cannot enforce global
uniqueness, and an unenforceable guarantee is worse than none — it invites
consumers to conflate two packages that merely share a name. A qualified
`<registry>:<id>` reference distinguishes them, and `:` is now barred from ids
so the separator stays available.

Installing the same id from two registries is therefore not a conflict. The
catalog is namespaced by registry and keeps both.

Ownership is registry policy, not package data. An optional `registry.yaml`
names a registry and records namespace claims. Those claims are explicitly
descriptive — a filesystem registry cannot authenticate a publisher, and
`publish` says so rather than implying it checked. Keeping the claim out of
packages leaves artifacts free of unverifiable assertions of authority, and
means package semantics do not change when a hosted registry appears later.

Spec: 3.2 (registry-scoped identity, qualified references), 17 (immutability
scoped to a registry), 20.1 and 20.2 (new), 18 (registry-manifest
validation), 21 (qualified references, reserved `local` name).

Reference CLI: parse_reference, check_registry_name, read_registry_manifest,
registry_name, namespace_policy; registry_package_path and
catalog_package_path split; resolve_installed reports ambiguity and returns
the source registry; iter_catalog; `add --as`; closed-namespace warning on
publish. Tests 11 -> 21.

The catalog layout changed. An existing catalog is detected and reported with
instructions rather than failing as "package not found". Signing, trust
scoring and federation remain non-goals and were not touched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bjefh8NUiEiahN4JLwoSKM

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 388925@bnt-lap001
Assistant-Session: 3507023f-e0fd-4a1e-9d90-a0d4217d1502

reference/tests/test_canned_prompts.py

@@ -220,3 +220,119 @@ inputs:
     )
     with pytest.raises(cp.CannedPromptError, match="cannot also reference"):
         cp.validate_package(pkg)
+
+
+MINIMAL = """\
+format: canned-prompt/v0.1
+id: practice/thing
+name: Thing
+version: 1.0.0
+summary: A thing.
+template: prompt.md
+inputs:
+  - name: greeting
+    required: false
+    default: hi
+"""
+
+
+def test_parse_reference() -> None:
+    assert cp.parse_reference("practice/thing") == (None, "practice/thing")
+    assert cp.parse_reference("house:practice/thing") == ("house", "practice/thing")
+    with pytest.raises(cp.CannedPromptError, match="malformed reference"):
+        cp.parse_reference("house:")
+
+
+def test_registry_name_falls_back_to_basename(tmp_path: Path) -> None:
+    registry = tmp_path / "upstream"
+    registry.mkdir()
+    assert cp.registry_name(registry) == "upstream"
+
+
+def test_registry_name_from_manifest(tmp_path: Path) -> None:
+    registry = tmp_path / "some-dir"
+    registry.mkdir()
+    (registry / "registry.yaml").write_text(
+        "format: canned-prompt-registry/v0.1\nname: house\n", encoding="utf-8"
+    )
+    assert cp.registry_name(registry) == "house"
+
+
+def test_registry_manifest_rejects_bad_format(tmp_path: Path) -> None:
+    registry = tmp_path / "r"
+    registry.mkdir()
+    (registry / "registry.yaml").write_text(
+        "format: something-else\nname: house\n", encoding="utf-8"
+    )
+    with pytest.raises(cp.CannedPromptError, match="unsupported registry format"):
+        cp.read_registry_manifest(registry)
+
+
+def test_registry_manifest_rejects_bad_policy(tmp_path: Path) -> None:
+    registry = tmp_path / "r"
+    registry.mkdir()
+    (registry / "registry.yaml").write_text(
+        "format: canned-prompt-registry/v0.1\n"
+        "name: house\n"
+        "namespaces:\n  practice:\n    policy: maybe\n",
+        encoding="utf-8",
+    )
+    with pytest.raises(cp.CannedPromptError, match="policy must be"):
+        cp.read_registry_manifest(registry)
+
+
+def test_namespace_policy(tmp_path: Path) -> None:
+    registry = tmp_path / "r"
+    registry.mkdir()
+    (registry / "registry.yaml").write_text(
+        "format: canned-prompt-registry/v0.1\n"
+        "name: house\n"
+        "namespaces:\n  practice:\n    owner: Ada\n    policy: closed\n",
+        encoding="utf-8",
+    )
+    assert cp.namespace_policy(registry, "practice/thing")[0] == "closed"
+    assert cp.namespace_policy(registry, "scratch/thing")[0] == "open"
+
+
+def install_into(catalog: Path, registry: str) -> None:
+    """Place a package in the catalog under a given registry name."""
+    dst = cp.catalog_package_path(catalog, registry, "practice/thing", "1.0.0")
+    dst.mkdir(parents=True)
+    (dst / "prompt.yaml").write_text(MINIMAL, encoding="utf-8")
+    (dst / "prompt.md").write_text("{{ greeting }}\n", encoding="utf-8")
+
+
+def test_same_id_from_two_registries_coexists(tmp_path: Path) -> None:
+    catalog = tmp_path / "catalog"
+    install_into(catalog, "house")
+    install_into(catalog, "upstream")
+    assert cp.catalog_registries(catalog) == ["house", "upstream"]
+
+    package_dir, registry = cp.resolve_installed(catalog, "house:practice/thing", None)
+    assert registry == "house"
+    assert package_dir.is_dir()
+
+
+def test_bare_id_in_two_registries_is_ambiguous(tmp_path: Path) -> None:
+    catalog = tmp_path / "catalog"
+    install_into(catalog, "house")
+    install_into(catalog, "upstream")
+    with pytest.raises(cp.CannedPromptError, match="more than one registry"):
+        cp.resolve_installed(catalog, "practice/thing", None)
+
+
+def test_bare_id_in_one_registry_resolves(tmp_path: Path) -> None:
+    catalog = tmp_path / "catalog"
+    install_into(catalog, "house")
+    _, registry = cp.resolve_installed(catalog, "practice/thing", None)
+    assert registry == "house"
+
+
+def test_legacy_catalog_layout_is_reported(tmp_path: Path) -> None:
+    catalog = tmp_path / "catalog"
+    legacy = catalog / "practice" / "thing" / "1.0.0"
+    legacy.mkdir(parents=True)
+    (legacy / "prompt.yaml").write_text(MINIMAL, encoding="utf-8")
+    (legacy / "prompt.md").write_text("{{ greeting }}\n", encoding="utf-8")
+    with pytest.raises(cp.CannedPromptError, match="pre-registry-scoped"):
+        cp.resolve_installed(catalog, "practice/thing", None)