The summary.
THE SERVICE WORKER TERMINATES WHEN IDLE
Anything held in a variable is lost. Persist state in storage and read it on each event.
REQUEST THE NARROWEST PERMISSIONS THAT WORK
Broad requests deter installation and increase review scrutiny. Prefer specific sites, optional permissions requested at the moment of need, and temporary access to the current tab.
Remove permissions no longer used — they remain declared and continue deterring installation.
AN EXTENSION CAN READ EVERYTHING ON PAGES IT REACHES, INCLUDING WHAT USERS TYPE
It is among the most privileged positions in a browser. Collect only what the feature requires, disclose it accurately, and treat page content and incoming messages as untrusted input.
NEVER INCLUDE SECRETS IN THE PACKAGE
It is downloadable and readable by anyone.
JUSTIFY EACH PERMISSION AGAINST A SPECIFIC FEATURE
Vague justification is a common cause of rejection.
EXTENSIONS THAT MODIFY SPECIFIC SITES BREAK WHEN THOSE SITES CHANGE
Maintenance is continuous, not occasional.
