diff --git a/codex-rs/.config/nextest.toml b/codex-rs/.config/nextest.toml
index 05ab6d6dd8..eb53c1d239 100644
--- a/codex-rs/.config/nextest.toml
+++ b/codex-rs/.config/nextest.toml
@@ -51,6 +51,7 @@ test-group = 'core_apply_patch_cli_integration'
 # each other and trip nextest's per-test timeout.
 filter = 'package(codex-core) & kind(test) & (test(remote_env) | test(view_image_routes_to_selected_remote_environment) | test(unified_exec_network_denial_emits_failed_background_end_event) | test(unified_exec_short_lived_network_denial_emits_failed_end_event))'
 test-group = 'core_remote_environment_integration'
+threads-required = "num-test-threads"
 slow-timeout = { period = "30s", terminate-after = 6 }
 
 [[profile.default.overrides]]
@@ -58,6 +59,7 @@ slow-timeout = { period = "30s", terminate-after = 6 }
 # other while waiting for append-only history rewrites on saturated CI runners.
 filter = 'package(codex-core) & kind(test) & (test(snapshot_rollback_followup_turn_trims_context_updates) | test(snapshot_rollback_past_compaction_replays_append_only_history) | test(thread_rollback_after_generated_image_drops_entire_image_turn_history))'
 test-group = 'core_thread_rollback_integration'
+threads-required = "num-test-threads"
 slow-timeout = { period = "30s", terminate-after = 6 }
 
 [[profile.default.overrides]]