fix: add lock on config.yaml to prevent TOCTOU coruption#50
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Zack (Zackaryia)
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Add race_test.go that demonstrates IIP-20714: multiple concurrent read-modify-write cycles on config.yaml without file locking causes invalid YAML, empty file reads, and silent data loss.
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Concurrent CLI invocations race on config.yaml through the non-atomic read-modify-write in New() (viper.WriteConfig + addDocCommentsToYAML). Wrap the entire critical section in an exclusive flock via gofrs/flock.
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This change is because the file lock fails before writing fails, so we need to edit the error message. Permission denied makes more sense in context.
…test Falls back to t.TempDir() when RACE_DATA_DIR is not set, so the test no longer skips/fatals when run individually or in CI outside of the race suite.
Ben Schwartz (btschwartz12)
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May 26, 2026
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Add race_test.go that demonstrates IIP-20714: multiple concurrent read-modify-write cycles on config.yaml without file locking causes invalid YAML, empty file reads, and silent data loss.