Upgrade Qwen3-Coder model and refactor package-body prompt for child summaries

CLAUDE.md

@@ -353,6 +353,11 @@ See [`../workspace/policies/jqwik-prompt-injection.md`](../workspace/policies/jq
 
 See [`../workspace/policies/ci-test-diagnostics.md`](../workspace/policies/ci-test-diagnostics.md).
 
+## PIT Mutation Testing
+
+See [`../workspace/policies/pit-mutation-testing.md`](../workspace/policies/pit-mutation-testing.md).
+Run PIT with the lifecycle prefix — `mvn test-compile org.pitest:pitest-maven:mutationCoverage`.
+
 ## Lombok Config
 
 See [`../workspace/policies/lombok-config.md`](../workspace/policies/lombok-config.md).

README.md

@@ -178,7 +178,7 @@ src/site/ai/
 - Output quality depends on chosen model
 
 ## TODO
-- **Expand PIT mutation-testing scope.** PIT is wired in `pom.xml` and runs on every CI build with `<mutationThreshold>100</mutationThreshold>`, but `<targetClasses>` is currently narrowed to a single class (`AiCompletionParser`). The intent is to exercise the wiring and gate against regressions on that single class today; widen `<targetClasses>` incrementally as additional classes reach mutation-test parity (i.e., add tests until 100% mutation coverage holds on the candidate class, then add it to the list). Final target: `<param>net.ladenthin.maven.llamacpp.aiindex.*</param>` matching the streambuffer pattern.
+- **Expand PIT mutation-testing scope.** `<targetClasses>` in `pom.xml` lists an explicit subset of classes verified at 100% mutation parity; widen it incrementally toward the whole `net.ladenthin.maven.llamacpp.aiindex.*` tree (the streambuffer whole-package model) as more classes reach parity. Generic PIT setup and invocation: see the [PIT policy](../workspace/policies/pit-mutation-testing.md).
 ## Recommended Models
 - Qwen2.5 Coder (balanced quality and speed)
 - Smaller instruct models for faster indexing