After 1889, there is no attempt to even pretend to institute a liberal constitution. A general quickly takes over, displaces the rest of the republican leadership, and makes himself dictator.
Its pretty similar to the contemporary Diaz regime in Mexico. In fact the economic development policies are very similar. There may be a republican, federal, and liberal constitution on paper, but the dictator at the time gets re-elected in every election, with a guaranteed majority in Congress and all the state legislatures, and he decides who the governors are.
At some point, this ends. It may be something similar to Vargas coming to power. It may be Vargas coming to power. It may be something similar to the Mexican revolution, or to the end of the military rule in Brazil in 1984. However, the transition happens sometime between 1910 and 1950.
The new regime is run by something similar to the Mexican PRI, however the economic policies are much sounder than the OTL twentieth century Brazil economic policies. The Brazilian version of the PRI gradually liberalizes and doesn't cling to power as long as its Mexican counterpart did.
This avoids much of the oligarchy, since the dictator cuts it down to size before it really develops, and when liberalization happens, the institutions and culture of the country are ready for it. I have referenced Mexico, and I think if you match twentieth century Mexican political history to Brazil's strategic situation and economic potential, you get a better result than both countries IOTL. But this also follows the South Korean development.
I would add no attempt to construct Brasilia, largely to avoid the additional debt and the isolation of the political class. If the center of Rio is too crowded, build a new government center in Barra de Tijuca and put the new government buildings there.
