In Jainism, Siddhi Tap refers to a particular type of austerity (tap) performed to attain spiritual achievements or "siddhi" (perfection, accomplishment, or spiritual success). The Agamas, which are canonical scriptures primarily in the Śvetāmbara tradition, describe various types of vrata (vows) and tap (austerities), but the term "Siddhi Tap" as a specific practice is not explicitly mentioned in the primary Agamas by that exact name.

However, the Agamas do discuss tapas (austerities) in general, both external (bāhya tap) and internal (abhyantara tap), which are means to achieve siddhi (spiritual accomplishments and ultimately liberation).

References from the Agamas:

1. Uttarādhyayana Sūtra, Chapter 30 (Tapasādhyayana)

This chapter lists and describes various austerities: - "There are two kinds of austerities: external and internal. External austerities are fasting, eating less than one's normal, giving up stimulating or tasty food, practicing bodily endurance, etc. Internal austerities are atonement, humility, service, study, renunciation, and meditation." _(Uttarādhyayana Sūtra 30.9-11)_

1. Ācāranga Sūtra, Book 1, Lecture 7 (Tapasādhyayana)

- The text describes the significance of austerities in purifying the soul: "By the performance of austerities, by knowledge, by right conduct, by carefulness, a wise man, after cutting off the fetters of his actions, becomes free from pain." _(Ācāranga Sūtra 1.7.13)_

Understanding Siddhi Through Tapas

The Agamas state that siddhi (spiritual perfection or liberation) is attained through the right combination of knowledge, faith, conduct, and especially tapas (austerity). While there is no direct mention of a "Siddhi Tap" as a named practice, the pursuit of tap is always for attaining siddhi.

Summary

• The Agamas do not mention "Siddhi Tap" specifically by name.
• They extensively discuss tapas (austerities) as essential for achieving siddhi (spiritual accomplishments and liberation).
• Key references are found in Uttarādhyayana Sūtra 30 and Ācāranga Sūtra 1.7.

If you are seeking a particular modern practice or tradition identified as "Siddhi Tap," it may be a later development or a traditional practice not directly named in the earliest Agama texts, but inspired by their teachings on tapas.