Keychain access
If CapMeter is showing "Keychain unavailable — data is saved without encryption", this page has the fix. It takes about a minute and nothing is lost.
What happened
CapMeter stores your Claude session locally, encrypted with a key that lives in your macOS Keychain. Something made that key unreadable — usually a denied permission prompt, but it can also happen after a macOS upgrade or if the keychain item was removed.
The app keeps working. Two things change while this lasts: it may look like you have been signed out, because the previous session could no longer be decrypted; and anything it saves in the meantime is written without encryption. Your usage history, settings and purchase are not affected.
The fix
1. Quit CapMeter — click its menu bar icon, then Quit.
2. Open Keychain Access (Applications → Utilities, or press ⌘ Space and type its name).
3. Search for CapMeter Safe Storage.
4. Right-click that item and choose Delete. This removes only CapMeter's encryption key, nothing else.
5. Open CapMeter again.
The app creates a fresh key on the next launch. If macOS asks for permission at that point, choose Always Allow — picking Allow only grants access once, so the prompt would come back on every launch.
After the fix
You may need to sign in to Claude once more, because the old session could no longer be decrypted. Your history, preferences and purchase are untouched — the app is not asking you to pay again.
If it comes back
A prompt that reappears on every launch usually means Allow was chosen instead of Always Allow. If the warning persists after following the steps above, please get in touch and mention your macOS version — that is a case worth looking at.