How did Beethoven turn the coda of the Appassionata Piano Sonata into something like a second development section?

In musical composition, a coda is typically a concluding section that follows the recapitulation to round off a movement. While a coda is not an essential element of sonata form, Ludwig van Beethoven frequently expanded this section to such a significant degree that it functioned similarly to a second development section.12

In his Piano Sonata No. 23 in F Minor (1804–05), known as the Appassionata, Beethoven utilized this technique to create a large-scale conclusion that extended beyond a simple summary of thematic material. By significantly lengthening the coda, he allowed for further exploration and transformation of the movement's themes, effectively creating a space for additional musical development that balances the structural weight of the preceding sections. This approach reflects a broader trend in Beethoven's middle period, where he often favored shorter expositions while simultaneously increasing the length and complexity of both the development and the coda to achieve a more profound sense of musical resolution.234