diff --git a/.gitea/workflows/gitea-build.yaml b/.gitea/workflows/gitea-build.yaml
index 5639d70..73ab746 100644
--- a/.gitea/workflows/gitea-build.yaml
+++ b/.gitea/workflows/gitea-build.yaml
@@ -30,18 +30,23 @@ jobs:
       - name: Test
         run: just test
 
+      - name: Debug Segfault
+        if: failure()
+        run: |
+          uname -a
+          cat /etc/os-release || true
+          clang --version
+          ulimit -a
+          free -h || true
+          SUDO=""; command -v sudo >/dev/null && SUDO=sudo
+          $SUDO apt-get install -y --no-install-recommends gdb >/dev/null
+          gdb -batch -ex run -ex bt -ex "info registers" build/tests
+
       - name: Build
         run: just release
 
-  # Cross-compiles for Windows so link breakages show up before a release.
-  # Runs after `build`: both jobs land on the same self-hosted runner, and the
-  # first run segfaulted `odin test` in `build` while `windows` was doing its
-  # (uncached) SDK download/splat at the same time - resource contention, not
-  # a code or toolchain bug (odin check passed; the test suite reproduces fine
-  # in isolation). Sequencing avoids that contention at the cost of a longer
-  # total run.
+  # Cross-compiles for Windows so link breakages show up before a release
   windows:
-    needs: build
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repository
diff --git a/AGENTS.md b/AGENTS.md
index d4ab144..efe0811 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -38,7 +38,7 @@ Commands (see `justfile`): `just run`, `just check`, `just test`, `just package
 6. **Windows builds are cross-compiled**: Odin can't link Windows binaries on Linux, so `just windows` builds objects with `-build-mode:obj` and links with `lld-link` against an xwin SDK. The VC runtime is linked statically; only Windows system DLLs are needed. New Odin core usage can need new import libs (e.g. `ole32.lib` for `os.user_data_dir`); the CI `windows` job catches this. Not yet tested on a real Windows machine.
 7. **Odin constant arrays can't be indexed at runtime**: lookup tables (`DECKS`, `LAYOUTS`, …) are `@(rodata)` globals instead of `::` constants.
 8. **Profile memory**: `profile` always allocates from the heap allocator, because the test runner frees each test's allocator afterwards.
-9. **CI jobs share one self-hosted runner**: `build` and `windows` in `gitea-build.yaml` land on the same machine. Running them concurrently once segfaulted `odin test` while `windows` was mid-SDK-download, so `windows` now runs with `needs: build` to avoid the contention.
+9. **CI's `build` job segfaults on `odin test`** (exit 139) on the self-hosted runner, even running alone — reproduces every push so far. Does not reproduce locally or in a plain `ubuntu:24.04` container with the same Odin version, so it's specific to the runner's actual job image/environment, not the test code. Under investigation; see the `Debug Segfault` diagnostic step in `gitea-build.yaml`.
 
 ## File Structure
 ```