What is the Buddhist interpretation of the flow state? Rephrased question:
Sometimes we become absorbed in an activity, such as writing an article, with intense focus and absorption (intentionally). How would Buddhist principles address this state?

Previous question as definition of mindfulness incorrect:
In being mindful we are aware of our thoughts, feelings, emotions and physical sensations
Sometimes we become absorbed in an activity, such as writing an article, with intense focus and absorption (intentionally). On the surface this appears to be in conflict with mindfulness. Is this the case?
Although meditation/immersion is, in general, unification of the mind, one must be careful.

“Yā kho, āvuso visākha, cittassa ekaggatā ayaṁ samādhi;


“Unification of the mind is immersion. MN44

One must be careful here because there is Right Immersion and Wrong Immersion. Flow unifies the mind with a feeling of effortless, peaceful, and expansive limitlessness in the pursuit of an activity. Yet flow always ends and is therefore unsatisfactory. One can actually crave flow--let's go surfing (or whatever) for the rest of our lives. So flow can lead to suffering. A flowing surfer who cannot surf due to old age and illness is suffering. Although flow is peaceful, it is incomplete. We need to look beyond flow.
If we observe any well-practiced Buddhist monk, we see something quite interesting. The robes of a monk flow, but the monk is invariably steady, imperturbable, radiant, and equanimous. The world flows around the monk without clinging.
What is that monk doing?

That mendicant feels inspired by the meaning and the teaching in that Dhamma, no matter how the Teacher or a respected spiritual companion teaches it. Feeling inspired, joy springs up. Being joyful, rapture springs up. When the mind is full of rapture, the body becomes tranquil. When the body is tranquil, one feels bliss.
And when blissful, the mind becomes immersed in samādhi. AN5.26

Although this sounds &quot;flowy&quot;, notice that the focus is the Dhamma, not some random activity.
Read the suttas, study the Dhamma, learn from good teachers and good friends. May that flow lead to peace.