The layout should be based on #5 and should deliver the following functionality:

• Draggable on the icon area.
• Simple, solid borders.
• White-on-black ability names present below icon.

Currently the predicate functions from the spec priority queues are called like this:

for index, ability in ipairs(spec) do
    local name = ability[1]
    local valid = ability[2]
    if valid() then
        return name
    end
end

It would be easy to inject the API:

for index, ability in ipairs(spec) do
    local name = ability[1]
    local valid = ability[2]
    if valid(API) then  -- Notice the argument.
        return name
    end
end

Currently you have to specifically refer to Protipper.API to hook into the API.

• Figure out which abilities to use as a Huntsman.
• Figure out their respective priorities.
• Figure out their respective conditions.

The AddOn should be able to:

• Figure out the next ability to use based on a (for now fixed as "Huntsman") priority list.

The addon needs to figure out if the player is using a known spec and if so load its priority list.

• Determine the key abilities for a known spec and check whether the player currently has these abilities.
• On role switch (or when gaining or losing abilities) find and load a matching spec.
• Have an empty fallback spec for unknown specs.

Make a sketch for the upcoming UI. It seems prudent to consider including the following information somewhere in the UI:

• The icon of the next ability to use.
• The name of the next ability to use.
• The keybinding of the next ability to use.
• Optional health and mana bars.

The AddOn should be able to:

• Update its ability suggestion whenever the following change for you, your target, or your pet:
  • Vitality/resources (health, mana, charge, etc.)
  • Buffs/debuffs
  • Stats (dexterity, strength, etc.)

The AddOn should be able to:

• Provide graceful fall backs for misspelled abilities, empty priority lists, etc.
• Not present the end user with a raw Lua error in any of the above circumstances.