Changes

|Feature status note=Product Management needs to flesh out has updated the feature page so that development can be . Team please review and set to unblockedif sufficient.

|Feature open issues and risks=* Is this only for desktop to desktop add-on syncing? Like AdBlock Plus. If this works across devices great! If not the priority is first to get desktop to desktop working and then worry about mobile. I need to understand the work involved. * Why does Sync need to be used for updating Add-ons? Would the user not be prompted to update the add-on through the browser? * Do we need some prompts or feedback when add-ons are synced, at all? * Are there any problems with large sets of add-on state being updated at once? Say the user has not used a device for a while and they use it again and a whole bunch of add-ons need to be updated.|Feature overview=Sync is a service to keep the Firefox experience consistent across multiple devices by ensuring user data is synced across various devices. This feature will enable add-ons to be synced across devices. Add-ons are synchronized between Sync clientssmall pieces of software that add new features or functionality to an installation of Firefox. Add-ons can augment Firefox with new features, foreign language dictionaries, or change its visual appearance. Through add-ons, you can customize Firefox to meet your needs and tastes.  Sync will ensure that add-ons are installed, uninstalled, updated, and enabled as they are changed on each client.|Feature users and use cases=Use cases:; Desktop browser to browser add-on install** A user has sync set up his work and home desktops** He goes to AMO and installs an add-on on his work computer** When he goes home and starts his Firefox browser the new add-on will be usable and shows up in the add-on tab ; Desktop browser to browser add-on uninstall** A user has sync set up his work and home desktops** At work, he goes to the add-on tab in the browser and removes the add-on** When he goes home and starts his Firefox browser this add-on will remove itself and not show up in the add-on tab ; Desktop browser to browser add-on disable** A user has sync set up his work and home desktops** At work, he goes to the add-on tab in the browser and disables an add-on** When he goes home and starts his Firefox browser this add-on will disable itself and not show up in the add-on tab ; Desktop browser to browser add-on enable** A user has sync set up his work and home desktops** At work, he goes to the add-on tab in the browser and enables a disabled add-on** When he goes home and starts his Firefox browser this add-on will enable itself and not show up in the add-on tab ;Not sure about the update case ;LEFT THESE USE CASES HERE TO MAKE SURE I COVERED EVERYTHING ; Install propagation : User installs an add-on on one browser. When a sync occurs, this add-on record is uploaded to the Sync server. When another browser in the Sync profile connects, the add-on is installed automatically.

; User enabled state propagation : User opens add-on manager and disables an add-on. Sync will propagate this change to other clients. Ditto for enabling. Sync should not propagate the enabled state if it is due to application compatibility (e.g. version upgrades causing incompatibilities). Only the user's explicit enabling and disabling of an add-on should be propagated. 

|Feature requirements=*When a user installs an add-on, the add-on will be installed on all the user's devices connected with Sync.*When a user uninstalls an add-on, the add-on will be uninstalled on all the user's devices connected with Sync*When a user disables an add-on, the add-on will be disabled on all the user's devices connected with Sync*When a user enables an add-on, the add-on will be enabled on all the user's devices connected with Sync*Not sure about the update version requirement.   ; Non-impact on add-on manager metrics : The presence of Sync should not skew the metrics in the add-on manager and addons.mozilla.org. Currently, some APIs on the AddonManager upload metrics.