Smoothing the on/off transition of mains LED lamps
There may be one big flaw but first the triac circuits....

It's tricky when using AC and triacs. Once you trigger a triac (with gate current) it stays "on" for the rest of the half power cycle of AC so there are two ways I see that may work: -


You get your micro to monitor the AC waveform and trigger the triac very late in positive and negative cycles to push smaller currents into the LED. Progressively move the trigger point closer to the start of each half cycle as you want brightness to increase
Similar to above but skip cycles of power completely.


And now the potential bad news. Dependent on your LED rectifier and current control circuit it may still try and push constant current into the LEDs until it can't do any more and then switches off. OR it may gracefully allow light intensity reductions below a certain a trigger point on the AC waveform but this may all be very cramped and difficult to control repeatedly. OR you might get smoke (hope not).