feat(authz): GroupKvRead/GroupKvWrite capabilities (§11.6 C2)

The shared-scope authz refinement for group collections. Two group-scoped caps
resolved via the existing group ancestor walk (effective_group_role):
GroupKvRead = viewer+, GroupKvWrite = editor+. Wired into app_id() (None —
group caps carry no app_id, so a bound API key is denied at the binding layer),
required_scope() (ScriptRead / ScriptWrite), the Member→group_member_grants
route, and group_role_satisfies. Unit test covers viewer-reads-not-writes,
editor-writes, outsider-denied, bound-key-denied up the chain.

The reads-open/writes-authed trust split (anonymous read bypass; anonymous
write fail-closed) is enforced at the service layer in the next commit — these
caps are the authenticated-principal refinement on top of the structural
subtree boundary.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/manager-core/src/authz.rs

@@ -142,6 +142,18 @@ pub enum Capability {
     /// the group; maps to `script:write` — the same tier as `AppWriteScript`
     /// for an app, lifted to the group owner.
     GroupScriptsWrite(GroupId),
+    /// Read a group-owned shared KV collection (§11.6). Resolved via the group
+    /// ancestor walk; viewer+ on the owning group. Maps to `script:read`. The
+    /// reads-open trust model means a script with no principal (anonymous
+    /// public HTTP) bypasses this check — the structural subtree boundary
+    /// (the collection only resolves for apps under the owning group) is the
+    /// hard isolation; this cap refines access for authenticated callers.
+    GroupKvRead(GroupId),
+    /// Write a group-owned shared KV collection (§11.6). editor+ on the owning
+    /// group; maps to `script:write`. Unlike the read cap, a write FAILS CLOSED
+    /// for an anonymous principal — mutation of shared data always requires an
+    /// authenticated caller (enforced at the service layer, not by skipping).
+    GroupKvWrite(GroupId),
     /// Send an outbound email from a script in this app (v1.1.7). Maps
     /// to `script:write` on API keys (sending mail is an outbound
     /// side-effect like an HTTP request). Granted to `editor`+.
@@ -208,7 +220,9 @@ impl Capability {
             | Self::GroupSecretsRead(_)
             | Self::GroupSecretsWrite(_)
             | Self::GroupScriptsRead(_)
-            | Self::GroupScriptsWrite(_) => None,
+            | Self::GroupScriptsWrite(_)
+            | Self::GroupKvRead(_)
+            | Self::GroupKvWrite(_) => None,
             Self::AppRead(id)
             | Self::AppWriteScript(id)
             | Self::AppWriteRoute(id)
@@ -260,7 +274,8 @@ impl Capability {
             | Self::AppVarsRead(_)
             | Self::GroupRead(_)
             | Self::GroupVarsRead(_)
-            | Self::GroupScriptsRead(_) => Scope::ScriptRead,
+            | Self::GroupScriptsRead(_)
+            | Self::GroupKvRead(_) => Scope::ScriptRead,
             Self::AppWriteScript(_)
             | Self::AppKvWrite(_)
             | Self::AppDocsWrite(_)
@@ -279,6 +294,7 @@ impl Capability {
             // the admin tier below.
             | Self::GroupSecretsWrite(_)
             | Self::GroupScriptsWrite(_)
+            | Self::GroupKvWrite(_)
             | Self::AppInvoke(_) => Scope::ScriptWrite,
             Self::AppWriteRoute(_) => Scope::RouteWrite,
             Self::AppManageDomains(_) => Scope::DomainManage,
@@ -466,7 +482,9 @@ async fn role_grants(
             | Capability::GroupSecretsRead(g)
             | Capability::GroupSecretsWrite(g)
             | Capability::GroupScriptsRead(g)
-            | Capability::GroupScriptsWrite(g) => {
+            | Capability::GroupScriptsWrite(g)
+            | Capability::GroupKvRead(g)
+            | Capability::GroupKvWrite(g) => {
                 group_member_grants(repo, principal.user_id, cap, g).await
             }
             // Creating a root-level group is an instance act — members
@@ -526,15 +544,17 @@ async fn group_member_grants(
 /// viewer→read, editor→write, group_admin(=AppAdmin)→admin.
 const fn group_role_satisfies(role: AppRole, cap: Capability) -> bool {
     match cap {
-        // viewer+ reads group metadata, config vars, and scripts.
+        // viewer+ reads group metadata, config vars, scripts, and shared KV.
         Capability::GroupRead(_)
         | Capability::GroupVarsRead(_)
-        | Capability::GroupScriptsRead(_) => true,
-        // editor+ writes config vars/secrets/scripts.
+        | Capability::GroupScriptsRead(_)
+        | Capability::GroupKvRead(_) => true,
+        // editor+ writes config vars/secrets/scripts and shared KV.
         Capability::GroupWrite(_)
         | Capability::GroupVarsWrite(_)
         | Capability::GroupSecretsWrite(_)
-        | Capability::GroupScriptsWrite(_) => {
+        | Capability::GroupScriptsWrite(_)
+        | Capability::GroupKvWrite(_) => {
             matches!(role, AppRole::Editor | AppRole::AppAdmin)
         }
         // group_admin manages the group + reads secret VALUES (the
@@ -1215,6 +1235,65 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn group_kv_caps_resolve_by_role_up_the_chain() {
+        // §11.6: shared-KV read is viewer+, write is editor+, both resolved via
+        // the group ancestor walk; an outsider gets nothing.
+        let repo = InMemoryAuthzRepo::default();
+        let root = GroupId::new();
+        let team = GroupId::new();
+        repo.add_group(root, None).await;
+        repo.add_group(team, Some(root)).await;
+
+        // A viewer at root can READ a descendant group's shared KV but not write.
+        let viewer = principal(InstanceRole::Member);
+        repo.grant_group(viewer.user_id, root, AppRole::Viewer)
+            .await;
+        assert!(can(&repo, &viewer, Capability::GroupKvRead(team))
+            .await
+            .unwrap()
+            .is_allow());
+        assert_eq!(
+            can(&repo, &viewer, Capability::GroupKvWrite(team))
+                .await
+                .unwrap(),
+            Decision::Deny
+        );
+
+        // An editor at root can WRITE it.
+        let editor = principal(InstanceRole::Member);
+        repo.grant_group(editor.user_id, root, AppRole::Editor)
+            .await;
+        assert!(can(&repo, &editor, Capability::GroupKvWrite(team))
+            .await
+            .unwrap()
+            .is_allow());
+
+        // An unrelated member gets neither.
+        let outsider = principal(InstanceRole::Member);
+        assert_eq!(
+            can(&repo, &outsider, Capability::GroupKvRead(team))
+                .await
+                .unwrap(),
+            Decision::Deny
+        );
+
+        // Group caps carry no app_id, so a bound key is denied at the binding
+        // layer regardless of role.
+        let bound = Principal {
+            user_id: AdminUserId::new(),
+            instance_role: InstanceRole::Owner,
+            scopes: Some(vec![Scope::ScriptWrite]),
+            app_binding: Some(AppId::new()),
+        };
+        assert_eq!(
+            can(&repo, &bound, Capability::GroupKvWrite(team))
+                .await
+                .unwrap(),
+            Decision::Deny
+        );
+    }
+
     #[tokio::test]
     async fn admin_implicitly_manages_the_whole_group_tree() {
         let repo = InMemoryAuthzRepo::default();