Write the config file atomically - #5190
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The config file was written with os.WriteFile, which truncates before it writes. When the write then failed, for example on a full disk, the file was left empty, and an empty config reads back as a logged-out flyctl, so every token refresh on a full disk logged the user out. Write to a temporary file beside the config, sync it, and rename it into place, so a failed write leaves the previous contents untouched. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DMttEkUAVhL7YZFRFjhHwB
Go reports every file as 0666 on Windows, and a read-only directory there does not block creating files inside it, so the permission check and the simulated write failure only hold on Unix. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DMttEkUAVhL7YZFRFjhHwB
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The config file was written with os.WriteFile, which truncates before it writes. When the write then failed, for example on a full disk, the file was left empty, and an empty config reads back as a logged-out flyctl, so every token refresh on a full disk logged the user out.
Write to a temporary file beside the config, sync it, and rename it into place, so a failed write leaves the previous contents untouched.
Claude-Session: https://claude.ai/code/session_01DMttEkUAVhL7YZFRFjhHwB