diff --git a/codex-rs/.config/nextest.toml b/codex-rs/.config/nextest.toml
index 01f4a98dc..f3f3ca260 100644
--- a/codex-rs/.config/nextest.toml
+++ b/codex-rs/.config/nextest.toml
@@ -8,12 +8,20 @@ retries = 1
 [profile.default.junit]
 path = "junit.xml"
 
+[profile.local]
+inherits = "default"
+
 [test-groups.app_server_protocol_codegen]
 max-threads = 1
 
 [test-groups.app_server_integration]
 max-threads = 1
 
+# Higher concurrency causes integration test timeouts under resource contention
+# on common developer machines.
+[test-groups.app_server_integration_local]
+max-threads = 4
+
 [test-groups.core_apply_patch_cli_integration]
 max-threads = 1
 
@@ -42,6 +50,12 @@ test-group = 'app_server_protocol_codegen'
 filter = 'package(codex-app-server) & kind(test)'
 test-group = 'app_server_integration'
 
+[[profile.local.overrides]]
+# Use up to four app-server subprocesses locally. The global nextest pool still
+# limits this to the machine's logical CPU count.
+filter = 'package(codex-app-server) & kind(test)'
+test-group = 'app_server_integration_local'
+
 [[profile.default.overrides]]
 # These tests exercise full Codex turns and apply_patch execution, and they are
 # sensitive to Windows runner process-startup stalls when many cases launch at once.
diff --git a/justfile b/justfile
index 3b993b767..fa32a19e7 100644
--- a/justfile
+++ b/justfile
@@ -75,11 +75,11 @@ install:
 # there should be no need to add `--all-features`.
 [unix]
 test *args:
-    RUST_MIN_STACK={{ rust_min_stack }} cargo nextest run --no-fail-fast "$@"
+    RUST_MIN_STACK={{ rust_min_stack }} NEXTEST_PROFILE=local cargo nextest run --no-fail-fast "$@"
 
 [windows]
 test *args:
-    $env:RUST_MIN_STACK = "{{ rust_min_stack }}"; cargo nextest run --no-fail-fast @($args | Select-Object -Skip 1)
+    $env:RUST_MIN_STACK = "{{ rust_min_stack }}"; $env:NEXTEST_PROFILE = "local"; cargo nextest run --no-fail-fast @($args | Select-Object -Skip 1)
 
 # Run from the repository root so scripts that resolve paths from `cwd` see
 # the same layout they use in GitHub Actions.