diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index 07be345..b325189 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -1,13 +1,16 @@
-name: Core CI
+name: Linux CI
 on: [push, pull_request]
+# Gitea currently has Ubuntu runners only; native Windows/macOS are separate
+# release gates. Cancel obsolete branch runs instead of accumulating work.
+concurrency:
+  group: searchi-ci-${{ github.ref }}
+  cancel-in-progress: true
 env:
   SEARCHI_FORCE_CPU: "1"
 jobs:
   core:
-    strategy:
-      matrix:
-        os: [windows-latest, ubuntu-latest, macos-latest]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
@@ -17,10 +20,8 @@ jobs:
       - run: cargo clippy --workspace --all-targets -- -D warnings
       - run: cargo test --workspace --locked
   desktop:
-    strategy:
-      matrix:
-        os: [windows-latest, ubuntu-latest, macos-latest]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 25
     defaults:
       run:
         working-directory: apps/desktop
diff --git a/crates/searchi-core/tests/documents.rs b/crates/searchi-core/tests/documents.rs
index f6a51bc..6b983a6 100644
--- a/crates/searchi-core/tests/documents.rs
+++ b/crates/searchi-core/tests/documents.rs
@@ -145,9 +145,21 @@ fn real_pdf_and_docx_return_matching_locations_and_persist() -> Result<()> {
     assert_eq!(batch.len(), 2);
     let remainder = index.passage_batch(batch[1].id, 256)?;
     assert_eq!(remainder.len(), 2);
-    assert!(remainder
+    // Directory traversal order differs by OS/filesystem. Pagination must
+    // preserve every passage exactly once, regardless of which file was first.
+    assert!(batch
+        .iter()
+        .all(|first| remainder.iter().all(|next| first.id != next.id)));
+    let all = batch.iter().chain(&remainder).collect::<Vec<_>>();
+    assert!(all
         .iter()
         .any(|passage| passage.source.kind == "paragraph" && passage.source.number == 3));
+    assert!(all
+        .iter()
+        .any(|passage| passage.source.kind == "page" && passage.source.number == 2));
+    assert!(index
+        .passage_batch(remainder.last().unwrap().id, 256)?
+        .is_empty());
     assert!(index.contains_path(&result[0].path)?);
     assert!(!index.contains_path("unknown")?);
     drop(index);