Was it true that Stalin was planning to invade Germany?

u/UnknownEel is referencing a comment by u/Georgy_K_Zhukov which in turn references a notable article by Viktor Suvorov that enforces the idea of Stalin's planned offensive against Nazi Germany. However, this article is highly disputed and both the author and specific article is accused of historical revisionism and cherrypicked sources. I read it a while ago and (As an example of some unsubstantiated claims) recall him referencing many Soviet offensive technologies to support his point, but he mostly relies on experimental and non-mass produced machinery as evidence (I remember him using a conceptual flying tank as a solid example for this). There are also numerous scholarly articles that refute much of Suvorov's claims that are a google search away.

In any case, I'll be using Richard Overy's Russia's War (Presents a good overview of the eastern front, would recommend anybody interested to read it), and specifically its 2nd chapter which focuses on pre-war Soviet policies, to say that Stalin was expecting an coming war with Nazi Germany and a subsequent one with the west, but did not find an immediate invasion in the early 1940's feasible due to limited resources.

The USSR and the West

Prior to the forming of the Molotov Ribbentrop pact, the USSR was actually in negotiations for a proposed alliance between itself, France, and the UK, to surround Nazi Germany. However, these never reached any solid agreement for several reasons. The west never took the USSR seriously and did not agree to any commitments. Poland would have outright refused any Soviet military movements into its borders to stop Hitler which in turn prevented the western allies to allow such actions. Another aspect of this was that the western diplomats actively showed disrespect. Overy makes an interesting note of how the French and British delegations traveled by sea instead of airliner which delayed negotiations. A more concrete note of this is that the British ambassadors did not have the proper authorities to make a military alliance whereas the French and Soviet representatives did. Moreover, the talks revealed that the Soviet army size (120 divisions and many more tanks than both sides combined) was severely greater than what the British could muster (16 divisions at the time), and somewhat larger than French strength (110 divisions). As a result, Stalin concluded that an alliance with the west was both impossible to attain and not as beneficial as he would have hoped. And if you contrast this with the Molotov-Ribbentrop negotiations, which Germany quite actively pursued, one could see why the USSR was more keen to negotiate with Germany. However, the elimination of collective security for the USSR meant that Germany's aggressive foreign policy was a much greater threat.

The Molotov-Ribbentrop Pact

It's no question that the USSR, Nazi Germany, and the West were each ideological enemies of each other, and armed conflict was a clear outcome to this feud. From this, the Molotov-Ribbentrop pact was an agreement out of Realpolitik and it is often argued that Stalin wanted this pact so that the Axis and western Allies could weaken each other for him to declare a war for revolution. However, Stalin certainly honored his side of the pact. Soviet supplies (Oil, timber, minerals, grain) crossed the border into Germany while its resources at times assisted Nazi operations, such as Soviet meteorological reports being given in preparation for the Battle of Britain and Soviet icebreakers helping Nazi naval attacks. Internally, the pact with the Nazis was honored with cultural works conveniently omitting the villainy of fascism and instead opting for the demonization of the western capitalists. On the German side however, supplies were less in quantity, especially immediately before the invasion expectedly. Again, Stalin still saw a war with Germany a likely reality in the coming future but believed the Molotov-Ribbentrop pact to be a reliable time cushion for him to improve the Soviet military, which would explain the cooperation between the two states from the pact.

Improving the Soviet Military and Plans for War

As I said numerous times earlier, the USSR was expecting war first with the Nazis and later with the west. Consequently, the Soviets used the perceived time given by its pact with Germany to prepare for the approaching conflicts. Consolidation with nearby states was one of the first policies pursued by Stalin, namely in the acquiring of military access with the Baltic states, and more infamously in the Winter War with Finland.

Modernization of the army was also the main strategy the state improvements that Stalin had in mind. The embarrassments of the Winter War prompted Stalin to replace the defense minister Voroshilov with Timoshenko, who pursued the ideas of Tukhachevsky in creating a professional army. We don't need to go into what was improved. What is important however is that he reassessments that these improvements incurred promptly revealed that the Soviet military was in no shape to conduct warfare with the other major powers. At the same time, Hitler found success across Europe and Khrushchev (Take him with a grain of salt) writes that Stalin was even struck with a great episode of anger when he heard that France capitulated in a matter of weeks. More importantly, these developments meant that Stalin had a shortening window of time to prepare the USSR for war. In response to this, the original line of defenses (The Stalin Line) was abandoned in favor of a new, more forward line, but this meant weeks of being open to a possible Nazi invasion.

While the army was not ready for war yet, Soviet doctrine certainly reflected this. While the original plans were for a solid defense and consequential push back of Nazi forces, these plans were obviously fantastical. Exercises in the winter of 1940 revealed numerous holes in the plan which Soviet command was aware of. Most of the planning during the months before the German invasion were spent in increased production to supply the air force, armored divisions, and the new Molotov Line. However, production for all of these were less than projected by the invasion (19 of the planned 106 air regiments, half of the planned 20 mechanized corps, and the Molotov Line was simply unfinished) while training for all of these bodies were insufficient.

From all this, you can see that the USSR was certainly not ready for war practically, nor did they really foresee an immediate war due to the Molotov-Ribbentrop Pact. Thus, while the Soviets did picture a war between itself and Germany, they're main strategy by 1941 was to professionalize its army rather than go on any offensives that the question suggests.