diff --git a/.github/workflows/opencode-review-dispatch.yml b/.github/workflows/opencode-review-dispatch.yml
index 6870be9384..26308e1a58 100644
--- a/.github/workflows/opencode-review-dispatch.yml
+++ b/.github/workflows/opencode-review-dispatch.yml
@@ -611,6 +611,20 @@ jobs:
           if ! reclaim; then
             echo "::warning::Could not reclaim stale coverage images; continuing."
           fi
+          # The sandbox writes workspaces as root, so the runner's own temp
+          # cleanup cannot remove them; sweep ones older than two hours that
+          # a cancelled or pre-cleanup run left behind, never this run's.
+          if [ -d "${RUNNER_TEMP:-}" ]; then
+            # Only run-numbered directories; shared ones (artifact, source,
+            # sandbox-result, tool-build) are never swept.
+            if ! find "$RUNNER_TEMP" -mindepth 1 -maxdepth 1 -type d \
+              \( -name 'opencode-coverage-[0-9]*-[0-9]*' -o -name 'opencode-coverage-tool-build-[0-9]*-[0-9]*' \) \
+              -mmin +120 ! -name "opencode-coverage-${GITHUB_RUN_ID}-*" \
+              ! -name "opencode-coverage-tool-build-${GITHUB_RUN_ID}-*" -print0 |
+              xargs -0 -r sudo rm -rf --; then
+              echo "::warning::Could not reclaim stale coverage workspaces; continuing."
+            fi
+          fi
 
       - name: Expose runner Rust toolchain
         # Self-hosted runners keep rustup's cargo in ~/.cargo/bin, which the
diff --git a/CHANGELOG.d/20260930-coverage-workspace-reclaim.md b/CHANGELOG.d/20260930-coverage-workspace-reclaim.md
new file mode 100644
index 0000000000..4e99d05c99
--- /dev/null
+++ b/CHANGELOG.d/20260930-coverage-workspace-reclaim.md
@@ -0,0 +1,6 @@
+## Fixed
+
+- Coverage jobs also remove run-numbered coverage workspaces older than two
+  hours. The sandbox writes them as root, so the runner's own temp cleanup
+  could not, and they refilled the self-hosted runner's disk. Shared coverage
+  directories are never removed.
diff --git a/tests/test_opencode_coverage_runner_hygiene.py b/tests/test_opencode_coverage_runner_hygiene.py
index a1c1f74dcd..a8910eac79 100644
--- a/tests/test_opencode_coverage_runner_hygiene.py
+++ b/tests/test_opencode_coverage_runner_hygiene.py
@@ -95,3 +95,33 @@ def test_missing_cargo_warns_readably(tmp_path: Path) -> None:
     result = _run(_step("Expose runner Rust toolchain")["run"], tmp_path, home=tmp_path / "home", path_dirs=[])
     assert result.returncode == 0
     assert "::warning::cargo is not installed" in result.stdout
+
+
+def test_reclaim_removes_only_old_coverage_workspaces(tmp_path: Path) -> None:
+    """Root-owned sandbox workspaces left by earlier jobs are swept with sudo."""
+    fake_bin = tmp_path / "bin"
+    _fake(fake_bin, "docker", "exit 0\n")
+    _fake(fake_bin, "sudo", 'exec "$@"\n')
+    runner_temp = tmp_path / "runner_temp"
+    old = runner_temp / "opencode-coverage-111-1"
+    old_build = runner_temp / "opencode-coverage-tool-build-111-1"
+    fresh = runner_temp / "opencode-coverage-222-1"
+    current = runner_temp / "opencode-coverage-333-1"
+    unrelated = runner_temp / "other-old"
+    shared = [runner_temp / f"opencode-coverage-{n}" for n in ("artifact", "sandbox-result", "source", "tool-build")]
+    for d in (old, old_build, fresh, current, unrelated, *shared):
+        (d / "x").mkdir(parents=True)
+    for d in (old, old_build, current, unrelated, *shared):
+        os.utime(d, (0, 0))
+    script = _step("Reclaim stale coverage images")["run"]
+    result = subprocess.run(
+        ["bash", "-c", script],
+        env={"PATH": f"{fake_bin}:/usr/bin:/bin", "RUNNER_TEMP": str(runner_temp),
+             "GITHUB_RUN_ID": "333", "HOME": str(tmp_path)},
+        capture_output=True, text=True,
+    )
+    assert result.returncode == 0, result.stderr
+    assert not old.exists() and not old_build.exists()
+    assert fresh.exists() and current.exists() and unrelated.exists()
+    # Shared, non-run directories are never swept, however old.
+    assert all(d.exists() for d in shared)
diff --git a/tests/test_pr_review_autofix_nvidia_nim_contract.py b/tests/test_pr_review_autofix_nvidia_nim_contract.py
index 5b045089d5..6e1918ed42 100644
--- a/tests/test_pr_review_autofix_nvidia_nim_contract.py
+++ b/tests/test_pr_review_autofix_nvidia_nim_contract.py
@@ -17,7 +17,7 @@
 DOCTORING_RECORD = Path("docs/doctoring/hourly-nvidia-nim-autofix.md")
 CHANGELOG = Path("CHANGELOG.md")
 REVIEW_DISPATCH_WORKFLOW = Path(".github/workflows/opencode-review-dispatch.yml")
-REVIEW_DISPATCH_BLOB_SHA = "6870be9384a5e6abfea0074ad310c58329feec2a"
+REVIEW_DISPATCH_BLOB_SHA = "26308e1a58f37f8aa15b3dd6d0453002ea1f50e8"
 
 
 def _workflow_text(path: Path) -> str: