1637, part 1
Depiction of a drawloom from the Tiangong Kaiwu, published in 1637
For some months, the emperor refuses to leave his private quarters.
This goes unnoticed by most of his subjects. The ordinary peasant farmer, city-dweller, even low-ranking members of the imperial bureaucracy have gotten used to a mostly distant and impersonal sovereign. The emperor’s grandfather had pretty much codified that practice, although it cannot have been said that emperors were especially hands-on even then.
Still, the extent of the emperor’s seclusion was apparently notable even to his contemporaries. The episode is mostly minimized in official chronicles, but historians are in agreement from other primary sources that the emperor was experiencing a severe depressive episode in response to the death of Yuan Chonghuan in battle.
Meanwhile, outside of the imperial palaces, events continue to turn. The four Oirats are sufficiently impressed by the Ming military expeditions to send embassies to Beijing pledging -- well, not submission, but something closer to friendship and also please don’t kill us. Ejei Khan, despite arguably “winning” the recent battle, takes a good look at the frankly unsustainable casualty figures that result from waging war with the Ming. During the following campaign seasons, he instead falls upon the Manchu, leaving China’s northern frontier mostly undisturbed for now.
In Dongshan, the announcement is officially made that gold has been discovered along the eastern coast. The reaction from the Portuguese, Dutch, and Spanish is one of grumbling at the missed opportunity -- or, at least, it would have been, but those nations are distracted by their quarrels with each other. The Dutch have been fighting the Spanish for generations over freedom and have been fighting the Portuguese for almost as long over colonial possessions. There’s intrigues afoot in Japan (where the conflict sometimes adopts religious overtones). Dutch and English cooperation was probably one of the factors that led to the merchant John Weddell being rebuffed from Chinese ports; he did not, apparently, endear himself to the Portuguese merchants who had already secured a foothold in the region.
Further afield, the great emperor of the Mughals, Shah Jahan, reacts with some bemusement to a letter from the Ming court. Having heard rumors of Shah Jahan’s persecution of the Jesuits in his realm, the Tianqi Emperor had apparently dictated a suitably disapproving response (although historians disagree on the exact wording of the authentic letter). Shah Jahan shrugs his shoulders and continues with his life. After all, his forces have just taken the stronghold of Nagpur and he’s got some neat ideas for building projects. Life is good.
Song Yingxing, an amateur scientist and failed exam candidate (seriously he made at least five different attempts at the jinshi degree before giving up), publishes his Tiangong Kaiwu (天工開物, “Explanation of Works Under Heaven”), one of the more interesting of the Ming-era encyclopedias. The text is very useful to historians, as it provides an extremely in-depth view of all aspects of the Ming economy circa 1637. Song includes an inscription thanking the gunpowder enthusiast Sun Yuanhua for his contributions to the book, although the Tiangong Kaiwu nonetheless includes some curious references to archaic but awesome-sounding gunpowder weapons (e.g. a description which greatly resembles the “thunder crash bomb” invented some hundreds of years earlier).
In Joseon, the king Injo (or, at least, whichever ministers are presently manipulating him) orders a massive offensive against the Manchus to the north. Some figures within the Joseon court dream of pushing far enough to restore the old frontiers of Balhae, one of the predecessor states to Goryeo (which was itself the immediate predecessor of the ruling Joseon dynasty). That’s probably a little bit out of reach, though. Injo finds himself in the curious position of sorta-technically cooperating with the Northern Yuan, who are encroaching on the Jurchens from the west as Joseon’s armies do so from the east. A formal agreement between Ejei Khan and King Injo is nowhere to be had, of course. Injo favors closer relations with the Ming and is not about to get in trouble by negotiating with the wrong people, even if the enemy of my enemy is my friend.
All these things happen, and then, as summer rolls around, the Tianqi Emperor finally emerges from seclusion...
 John Weddell was a real guy who existed IOTL and who failed to make much of an impression in China on account of the Portuguese already being there. (It’s honestly amazing how little success the English / British had in China literally up until the Opium Wars. Then again, their ambitions were generally focused elsewhere.)
 Song Yingxing was also a real person from OTL. ITTL he has managed to get a bit more expert insight on his writing, so his description of gunpowder weapons is a little less anachronistic than IOTL. But only a little bit. Dude really liked his long-obsolete explosives.
 This is in sharp contrast with OTL, where Hong Taiji had proclaimed himself founding emperor of the Qing dynasty and then launched another invasion of Joseon, in which (predictably) the Qing won handily.