Add agent rehearsal harness, findings, and per-run evidence for split-loop-with-lambda

Six scripted pi sub-agent runs (3 tool regimes × 2 models) rehearsed the
exercise; deterministic gate = solution test + approved file. Key results:
mandated CLI triples cost on the strong model (4:06 vs 0:39, PASS both);
weak model fails only under the mandate (A+Q), passes when free or optional.
Drift documented with code: scorer.updateSelection left inside the extracted
method (A+Q, C+Q). Harness in tools/rehearse; summary in
rehearsal-findings.md; per-run evidence in rehearsal-runs/; cheat sheet in
rehearse-with-agent.md corrected (lambda-typed parameters unsupported).

tools/rehearse/setup.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+# Stage 1 — one-time setup: build java-refactoring-mcp, install the CLI wrapper,
+# create the pristine kata workspace, and smoke-test the CLI.
+# Idempotent: safe to re-run. Artifacts live in /tmp/rehearsal (scratch space).
+set -euo pipefail
+
+MCP_REPO=/tmp/java-refactoring-mcp
+KATA=/tmp/IceCreamForecasting-Refactoring-Kata
+SCRATCH=/tmp/rehearsal
+MVN=/tmp/apache-maven-3.9.9/bin/mvn
+# Temurin JDK downloaded to /tmp by this script (system has JRE only, no javac)
+if [ ! -x /tmp/jdk21/bin/javac ]; then
+  echo "== 0. Downloading Temurin JDK 21 to /tmp/jdk21 (system has no javac) =="
+  curl -sL -o /tmp/jdk21.tar.gz \
+    "https://api.adoptium.net/v3/binary/latest/21/ga/linux/x64/jdk/hotspot/normal/eclipse"
+  mkdir -p /tmp/jdk21
+  tar -xzf /tmp/jdk21.tar.gz -C /tmp/jdk21 --strip-components=1
+fi
+export JAVA_HOME=/tmp/jdk21
+export PATH="$JAVA_HOME/bin:$PATH"
+
+mkdir -p "$SCRATCH/bin"
+
+echo "== 1. Build the tool (skip if fat jars exist) =="
+CLI_JAR=$(ls "$MCP_REPO"/refactor-cli/target/refactor-cli-*-fat.jar 2>/dev/null | head -1 || true)
+MCP_JAR=$(ls "$MCP_REPO"/refactor-mcp/target/refactor-mcp-*-fat.jar 2>/dev/null | head -1 || true)
+if [ -z "${CLI_JAR:-}" ]; then
+  (cd "$MCP_REPO" && "$MVN" -q package -DskipTests)
+fi
+CLI_JAR=$(ls "$MCP_REPO"/refactor-cli/target/refactor-cli-*-fat.jar | head -1)
+MCP_JAR=$(ls "$MCP_REPO"/refactor-mcp/target/refactor-mcp-*-fat.jar | head -1)
+echo "   CLI jar: $CLI_JAR"
+echo "   MCP jar: $MCP_JAR (for reference; not needed by this rehearsal)"
+echo "   JAVA_HOME: $JAVA_HOME"
+
+echo "== 2. Install CLI wrapper =="
+cat > "$SCRATCH/bin/java-refactor" <<EOF
+#!/usr/bin/env bash
+exec "$JAVA_HOME/bin/java" -jar "$CLI_JAR" "\$@"
+EOF
+chmod +x "$SCRATCH/bin/java-refactor"
+
+echo "== 3. Pristine kata workspace (never touched by runs) =="
+rm -rf "$SCRATCH/pristine"
+cp -r "$KATA/java" "$SCRATCH/pristine"
+rm -rf "$SCRATCH/pristine/target"
+
+echo "== 4. Baseline: pristine compiles (tests EXPECTED to fail — Scorer is flaky by design) =="
+( cd "$SCRATCH/pristine" \
+  && PATH="$JAVA_HOME/bin:/tmp/apache-maven-3.9.9/bin:$PATH" \
+     mvn -q test-compile ) \
+  && echo "   test-compile OK" \
+  || { echo "   test-compile FAILED"; exit 1; }
+# Demonstrate the expected baseline failure (flaky approval via Scorer's Random + today's date):
+( cd "$SCRATCH/pristine" \
+  && PATH="$JAVA_HOME/bin:/tmp/apache-maven-3.9.9/bin:$PATH" \
+     mvn -q test ) > "$SCRATCH/baseline-test.log" 2>&1 \
+  && echo "   NOTE: pristine tests unexpectedly PASSED" \
+  || echo "   pristine tests fail as expected (untestable Scorer dependency) — see baseline-test.log"
+
+echo "== 5. Smoke test: java-refactor --help =="
+PATH="$SCRATCH/bin:$PATH" java-refactor --help > "$SCRATCH/smoke-help.txt" 2>&1 \
+  && head -3 "$SCRATCH/smoke-help.txt"
+
+echo "== 6. Smoke test: dry-run extract of the weather loop =="
+# LongRangeForecasts.java lines 29-36: the for-loop over interestingDates.
+rm -rf "$SCRATCH/smoke"
+cp -r "$SCRATCH/pristine" "$SCRATCH/smoke"
+( cd "$SCRATCH/smoke" \
+  && PATH="$SCRATCH/bin:$PATH" java-refactor extract \
+       --file src/main/java/codingdojo/LongRangeForecasts.java \
+       --start-line 29 --start-column 9 \
+       --end-line 36 --end-column 10 \
+       --name collectExpectedWeather --dry-run ) \
+  > "$SCRATCH/smoke-extract.txt" 2>&1 \
+  && echo "   dry-run OK (see /tmp/rehearsal/smoke-extract.txt)" \
+  || { echo "   dry-run FAILED — inspect /tmp/rehearsal/smoke-extract.txt"; exit 1; }
+
+echo
+echo "Stage 1 done. Artifacts in $SCRATCH:"
+ls -la "$SCRATCH"