fix(node): owner-gate create_task repo_id against hosted repos

crates/gitlawb-node/src/api/mod.rs

@@ -223,6 +223,11 @@ mod authz_guard {
             (events, "list_repo_events", "authorize_repo_read("),
             // Bucket C — signer-self: the acting DID is matched/bound to auth.0
             (tasks, "create_task", "did_matches("),
+            // #496: create_task is signer-self AND owner-when-repo-scoped — a
+            // repo_id naming a hosted repo admits tasks only from its owner.
+            // Both halves are pinned: the did_matches row guards the signer
+            // binding, this one the repo-ownership gate.
+            (tasks, "create_task", "require_repo_owner("),
             (tasks, "claim_task", "did_matches("),
             (tasks, "complete_task", "did_matches("),
             (tasks, "fail_task", "did_matches("),

crates/gitlawb-node/src/api/tasks.rs

@@ -101,6 +101,40 @@ pub async fn create_task(
     if !crate::api::did_matches(&auth.0, &body.delegator_did) {
         return Err(forbidden("delegator_did must be the authenticated signer"));
     }
+    // #496: a caller-supplied repo_id must name a repo the caller owns. Without
+    // this, any signed caller can plant a task — payload and UCAN included —
+    // under a foreign repo id, where repo-gated task reads surface it exactly
+    // to that repo's readers and the named assignee can claim it. Resolve the
+    // id against hosted repos: a hosted, non-quarantined repo admits tasks
+    // only from its owner. An id naming no hosted repo (unknown, or
+    // quarantined — which is hidden as if it did not exist, so 403ing it
+    // would confirm a real id) is kept as an opaque label with no existence
+    // oracle either way; such ids resolve to no hosted repo, so repo-scoped
+    // task read gates treat them as unscoped (delegator/assignee-only under
+    // the #268/#464 visibility contract). Repo-less tasks are unaffected.
+    if let Some(repo_id) = body.repo_id.as_deref() {
+        let record = state.db.get_repo_by_id(repo_id).await.map_err(|e| {
+            (
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json(json!({ "error": e.to_string() })),
+            )
+        })?;
+        if let Some(record) = record {
+            let quarantined = state
+                .db
+                .is_repo_quarantined(&record.id)
+                .await
+                .map_err(|e| {
+                    (
+                        StatusCode::INTERNAL_SERVER_ERROR,
+                        Json(json!({ "error": e.to_string() })),
+                    )
+                })?;
+            if !quarantined && crate::api::require_repo_owner(&record, &auth.0).is_err() {
+                return Err(forbidden("only the repo owner can file tasks against it"));
+            }
+        }
+    }
     let now = Utc::now().to_rfc3339();
     let task = AgentTask {
         id: Uuid::new_v4().to_string(),

crates/gitlawb-node/src/graphql/mutation.rs

@@ -36,6 +36,27 @@ impl MutationRoot {
         }
         let delegator_did = caller.to_string();
         let db = ctx.data_unchecked::<Arc<Db>>();
+        // #496: same repo-ownership gate as the REST handler — a repo_id
+        // naming a hosted, non-quarantined repo admits tasks only from its
+        // owner, so a stranger cannot file under a foreign repo id. Unknown
+        // or quarantined ids stay oracle-free opaque labels (unscoped under
+        // the #268/#464 read contract); repo-less tasks unaffected.
+        if let Some(repo_id) = input.repo_id.as_deref() {
+            let record = db
+                .get_repo_by_id(repo_id)
+                .await
+                .map_err(crate::graphql::graphql_db_err)?;
+            if let Some(record) = record {
+                let quarantined = db
+                    .is_repo_quarantined(&record.id)
+                    .await
+                    .map_err(crate::graphql::graphql_db_err)?;
+                if !quarantined {
+                    crate::api::require_repo_owner(&record, caller)
+                        .map_err(crate::graphql::graphql_app_err)?;
+                }
+            }
+        }
         let now = Utc::now().to_rfc3339();
         let task = AgentTask {
             id: Uuid::new_v4().to_string(),
@@ -332,4 +353,63 @@ mod tests {
             errors(&resp)
         );
     }
+
+    /// #496 (GraphQL): createTask applies the same repo-ownership gate as the
+    /// REST handler — a stranger naming a hosted repo is rejected, while the
+    /// owner files.
+    #[sqlx::test]
+    async fn create_task_rejects_foreign_repo_id(pool: PgPool) {
+        let state = crate::test_support::test_state(pool).await;
+        let owner = "did:key:zGQLTASKOWNERAAAAAAAAAAAAAAAAAAAAAAAAAA";
+        let stranger = "did:key:zGQLTASKSTRANGERBBBBBBBBBBBBBBBBBBBBBB";
+        let now = chrono::Utc::now();
+        let repo = crate::db::RepoRecord {
+            id: uuid::Uuid::new_v4().to_string(),
+            name: "gql-task-gate-repo".to_string(),
+            owner_did: owner.to_string(),
+            description: None,
+            is_public: true,
+            default_branch: "main".to_string(),
+            created_at: now,
+            updated_at: now,
+            disk_path: "/tmp/gql-task-gate-repo".to_string(),
+            forked_from: None,
+            machine_id: None,
+        };
+        state.db.create_repo(&repo).await.expect("seed repo");
+        let schema = state.graphql_schema.as_ref();
+
+        let q = |actor: &str| {
+            format!(
+                r#"mutation {{ createTask(delegatorDid: "{actor}", input: {{ kind: "build", capability: "repo:write", repoId: "{}" }}) {{ id }} }}"#,
+                repo.id
+            )
+        };
+
+        // Stranger signs as themselves (so the signer binding passes) but
+        // names the victim's repo → rejected by the ownership gate, leaking
+        // nothing about the repo.
+        let resp = schema
+            .execute(Request::new(q(stranger)).data(AuthenticatedDid(stranger.into())))
+            .await;
+        let errs = errors(&resp);
+        assert!(
+            errs.contains("repo owner"),
+            "a non-owner must not file under a foreign repo id: {errs}"
+        );
+        assert!(
+            !errs.contains(&repo.id) && !errs.contains(owner),
+            "denial must leak nothing about the repo: {errs}"
+        );
+
+        // The owner files under their own repo id.
+        let resp = schema
+            .execute(Request::new(q(owner)).data(AuthenticatedDid(owner.into())))
+            .await;
+        assert!(
+            errors(&resp).is_empty(),
+            "the owner should file against their repo: {}",
+            errors(&resp)
+        );
+    }
 }

crates/gitlawb-node/src/test_support.rs

@@ -590,6 +590,112 @@ mod tests {
         );
     }
 
+    /// #496: create_task must not bind a caller-supplied repo_id verbatim. A
+    /// signed caller naming a hosted repo it does not own is rejected (403,
+    /// leaking nothing about the repo); the owner files (201); repo-less and
+    /// unknown-id tasks stay allowed (unknown ids are oracle-free opaque
+    /// labels, unscoped under the #268/#464 read contract); and a quarantined
+    /// repo id is treated as unknown (no 403 oracle on quarantined existence).
+    #[sqlx::test]
+    async fn create_task_rejects_foreign_repo_id(pool: PgPool) {
+        let owner = "did:key:zTASKREPOOWNERAAAAAAAAAAAAAAAAAAAAAAAAAA";
+        let stranger = "did:key:zTASKREPOSTRANGERBBBBBBBBBBBBBBBBBBBBBB";
+        let state = test_state(pool).await;
+        let repo = seed_repo(owner, "task-gate-repo");
+        state.db.create_repo(&repo).await.expect("seed repo");
+
+        let router = || {
+            Router::new()
+                .route(
+                    "/api/v1/tasks",
+                    axum::routing::post(crate::api::tasks::create_task),
+                )
+                .with_state(state.clone())
+        };
+        let post_as = |signer: &str, body: String| {
+            router().oneshot(signed_request_as(
+                signer,
+                Method::POST,
+                "/api/v1/tasks",
+                Body::from(body),
+            ))
+        };
+        let body_with = |signer: &str, repo_id: Option<&str>| {
+            let repo_field = repo_id
+                .map(|id| format!(r#","repo_id":"{id}""#))
+                .unwrap_or_default();
+            format!(
+                r#"{{"kind":"build","capability":"repo:write","delegator_did":"{signer}"{repo_field}}}"#
+            )
+        };
+
+        // Stranger filing under the victim's repo id → exact 403.
+        let resp = post_as(stranger, body_with(stranger, Some(&repo.id)))
+            .await
+            .unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::FORBIDDEN,
+            "a non-owner must not file tasks against a foreign repo id"
+        );
+        let bytes = axum::body::to_bytes(resp.into_body(), usize::MAX)
+            .await
+            .unwrap();
+        let text = String::from_utf8_lossy(&bytes);
+        assert!(
+            text.contains(r#""error":"forbidden""#),
+            "denial must keep the forbidden envelope: {text}"
+        );
+        assert!(
+            !text.contains(&repo.id) && !text.contains(owner),
+            "denial must leak nothing about the repo: {text}"
+        );
+
+        // Owner filing under their own repo id → 201.
+        let resp = post_as(owner, body_with(owner, Some(&repo.id)))
+            .await
+            .unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::CREATED,
+            "the owner must be able to file tasks against their repo"
+        );
+
+        // Repo-less task → 201 (unaffected).
+        let resp = post_as(stranger, body_with(stranger, None)).await.unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::CREATED,
+            "repo-less task creation must keep working"
+        );
+
+        // Unknown repo id → 201 as an opaque label.
+        let resp = post_as(stranger, body_with(stranger, Some("no-such-repo-id")))
+            .await
+            .unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::CREATED,
+            "an id naming no hosted repo stays an opaque label"
+        );
+
+        // Quarantined repo id → treated as unknown (201), never a 403 that
+        // would confirm the id names a real repo.
+        state
+            .db
+            .set_repo_quarantine(&repo.id, true)
+            .await
+            .expect("quarantine");
+        let resp = post_as(stranger, body_with(stranger, Some(&repo.id)))
+            .await
+            .unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::CREATED,
+            "a quarantined repo id must not 403 (existence oracle)"
+        );
+    }
+
     /// N3: get_tree gates on the REQUESTED subtree, not the repo root. A caller
     /// denied a withheld subtree is rejected there (404) but passes the gate on a
     /// non-withheld path (so the rejection is path-scoped, not repo-wide).