test(agent-eval): persist offload accuracy/adoption eval harness + front-load hook

Reproducible suite measuring the managed CodeGraph AI offload and the front-load
UserPromptSubmit hook (approach 1) vs raw codegraph and no-codegraph, across repo
sizes, on time / main-session tokens+cost / CodeGraph-AI tokens+cost / accuracy.
All agent arms run claude -p sonnet --effort high; eval-only, nothing shipped.

- offload-eval-setup.sh: clone + index 4 memory-probe-verified "not-trained-on" repos
  (mtkruto/postybirb/shapeshift/trezor — small→large) so the no-codegraph baseline is honest.
- offload-eval-3arm.sh / -frontload.sh: one repo, the arms (offload/raw/nocg, frontload).
- offload-eval-matrix.sh / -frontload-matrix.sh: drive all 4 tiers.
- offload-eval-hook.mjs: the front-load hook (self-locates its engine; CG_FRONTLOAD_DEBUG to log).
- offload-eval-metrics.mjs / -judge.mjs (Sonnet) / -summarize.mjs: extract, score, aggregate.
- offload-eval-ground-truth.json: source-verified canonical flows (the judge's reference).
- offload-eval.md: usage + the 2026-06 findings (raw = the win; offload least-accurate;
  front-load solves adoption but exposes explore's dynamic-dispatch gaps).

Scripts are path-portable (self-locating $HERE/$ENGINE; AGENT_EVAL_OUT scratch dir).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/agent-eval/offload-eval-matrix.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# Drive the 3-arm campaign (offload/raw/nocg) across all 4 tiers, n reps each, into one
+# results.jsonl. Reads the canonical question per repo from offload-eval-ground-truth.json.
+# Env: REPS (default 3)  AGENT_EVAL_OUT=<scratch dir>
+set -uo pipefail
+HERE="$(cd "$(dirname "$0")" && pwd)"
+OUT="${AGENT_EVAL_OUT:-/tmp/cg-offload-eval}"
+GT="$HERE/offload-eval-ground-truth.json"
+REPS="${REPS:-3}"
+export RESULTS="$OUT/results.jsonl"
+: > "$RESULTS"
+for repo in mtkruto postybirb shapeshift trezor; do
+  case "$repo" in mtkruto) tier=small;; postybirb) tier=medium;; shapeshift) tier=complex;; trezor) tier=large;; esac
+  Q=$(node -e "console.log(JSON.parse(require('fs').readFileSync(process.argv[1],'utf8'))[process.argv[2]].question)" "$GT" "$repo")
+  echo ""; echo "### $repo ($tier)  $(date +%H:%M:%S)"
+  bash "$HERE/offload-eval-3arm.sh" "$OUT/repos/$repo" "$tier" "$REPS" "$Q"
+done
+echo ""; echo "###### MATRIX DONE -> $RESULTS ($(wc -l < "$RESULTS") runs).  Judge + summarize with:"
+echo "  node $HERE/offload-eval-judge.mjs --results $RESULTS --truth $GT --out $OUT/judged.jsonl"
+echo "  node $HERE/offload-eval-summarize.mjs $OUT/judged.jsonl"