diff --git a/.config/nextest.toml b/.config/nextest.toml
new file mode 100644
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+# Nextest configuration for Turborepo
+# See https://nexte.st/book/configuration.html
+
+[test-groups]
+# turborepo-process tests should run serially to avoid resource contention
+# and timing issues, especially on macOS where PTY devices are limited
+turborepo-process-serial = { max-threads = 1 }
+
+# Integration tests that spawn turbo binaries should run serially to avoid
+# race conditions with binary detection and stdout/stderr capture
+turborepo-integration-serial = { max-threads = 1 }
+
+[[profile.default.overrides]]
+# Run all tests in the turborepo-process crate serially
+filter = 'package(turborepo-process)'
+test-group = 'turborepo-process-serial'
+
+[[profile.default.overrides]]
+# Run integration tests that use check_json_output! serially
+# These tests spawn turbo processes and parse JSON from stdout
+filter = 'package(turbo) and (test(boundaries) or test(query) or test(ls))'
+test-group = 'turborepo-integration-serial'