fix(core): honor wildcard capabilities in Ucan::can, matching is_attenuated_by (#200)

* fix(core): honor wildcard capabilities in Ucan::can, matching is_attenuated_by

Ucan::can did strict equality on both resource and action, so a validly
delegated wildcard capability (with: "*", or can: "*" / "repo/admin") could
never match a concrete runtime request even though is_attenuated_by treats
those same values as wildcards during delegation-chain verification.

Not a security issue: the mismatch only produces false negatives (denying a
capability the delegation chain actually grants), never false positives.
Dormant today since no production code path calls can() yet — auth's
caller_authorized_to_push is pure did_matches(), with the UCAN-capability
check noted as future (Phase 2) work.

Makes can() mirror is_attenuated_by's semantics: the stored capability plays
the "parent" role, so with == "*" matches any resource and can == "*" or
"repo/admin" matches any action.

Closes #199

* test: add can_honors_action_wildcard unit test for Ucan::can

Author: euxaristia

crates/gitlawb-core/src/ucan.rs

@@ -187,11 +187,17 @@ impl Ucan {
     }
 
     /// Check if this UCAN grants a specific capability on a resource.
+    ///
+    /// Mirrors `Capability::is_attenuated_by`'s wildcard semantics: a stored
+    /// capability of `with: "*"` or `can: "*"` / `"repo/admin"` covers any
+    /// requested resource/action, since a valid delegation chain can produce
+    /// exactly that capability (see `is_attenuated_by`).
     pub fn can(&self, resource: &str, action: &str) -> bool {
-        self.payload
-            .att
-            .iter()
-            .any(|cap| cap.with == resource && cap.can == action)
+        self.payload.att.iter().any(|cap| {
+            let resource_ok = cap.with == resource || cap.with == "*";
+            let action_ok = cap.can == action || cap.can == "*" || cap.can == caps::REPO_ADMIN;
+            resource_ok && action_ok
+        })
     }
 
     /// Encode to a compact JSON string (the wire format).
@@ -312,6 +318,63 @@ mod tests {
         assert!(!ucan.can("gitlawb://repos/test/repo", caps::PR_MERGE));
     }
 
+    #[test]
+    fn can_honors_resource_wildcard() {
+        let issuer = Keypair::generate();
+        let audience = Keypair::generate().did();
+
+        let ucan = Ucan::issue(
+            &issuer,
+            audience,
+            vec![Capability::new("*", caps::GIT_PUSH)],
+            None,
+        )
+        .unwrap();
+
+        assert!(ucan.can("gitlawb://repos/test/repo", caps::GIT_PUSH));
+        assert!(ucan.can("gitlawb://repos/other/repo", caps::GIT_PUSH));
+        assert!(!ucan.can("gitlawb://repos/test/repo", caps::PR_MERGE));
+    }
+
+    #[test]
+    fn can_honors_repo_admin_action_wildcard() {
+        let issuer = Keypair::generate();
+        let audience = Keypair::generate().did();
+
+        let ucan = Ucan::issue(
+            &issuer,
+            audience,
+            vec![Capability::new(
+                "gitlawb://repos/test/repo",
+                caps::REPO_ADMIN,
+            )],
+            None,
+        )
+        .unwrap();
+
+        assert!(ucan.can("gitlawb://repos/test/repo", caps::GIT_PUSH));
+        assert!(ucan.can("gitlawb://repos/test/repo", caps::PR_MERGE));
+        assert!(!ucan.can("gitlawb://repos/other/repo", caps::GIT_PUSH));
+    }
+
+    #[test]
+    fn can_honors_action_wildcard() {
+        let issuer = Keypair::generate();
+        let audience = Keypair::generate().did();
+
+        let ucan = Ucan::issue(
+            &issuer,
+            audience,
+            vec![Capability::new("gitlawb://repos/test/repo", "*")],
+            None,
+        )
+        .unwrap();
+
+        assert!(ucan.can("gitlawb://repos/test/repo", caps::GIT_PUSH));
+        assert!(ucan.can("gitlawb://repos/test/repo", caps::PR_MERGE));
+        assert!(!ucan.can("gitlawb://repos/other/repo", caps::GIT_PUSH));
+    }
+
     #[test]
     fn bootstrap_ucan() {
         let issuer = Keypair::generate();