Adaptive-GEPA: Make Your Harness Fit Heterogeneous Requests

Reflective optimizers such as GEPA improve language-model prompts from execution traces and evaluator feedback; full-program extensions can also rewrite tools and control flow. In practice, a user hands the same endpoint heterogeneous requests whose effective solutions require different tools, reasoning modes, and control flow. Optimizing one shared program leaves this division of work implicit in source-code search, while optimizing a separate program per request family fixes it beforehand. We introduce Adaptive-GEPA, which learns both how to divide requests and how to solve them. It evolves a router and a library of specialist programs under one search budget. The router's instructions, each specialist's description, and its program code are plain, human-readable text, edited from feedback. To combine branches, it aligns specialists by the requests they handle and inherits descriptions together with programs. On a fixed mixture of four task families, the reported Qwen3-8B run evolves four experts without supplying family labels to the router or reflection model; its routing matches the task partition on all 651 test requests. Its family-mean test score ($\times 100$) rises from $52.6$ to $70.6$, compared with $62.5$ for GEPA's full-program adapter and $54.0$ for GRPO at a nominal budget of 18,000 scored calls. Figure 1 summarizes the learning curves, final test scores, and routing agreement.