diff --git a/scripts/toolperf_abeval/README.md b/scripts/toolperf_abeval/README.md
new file mode 100644
index 0000000000..0f8525eaac
--- /dev/null
+++ b/scripts/toolperf_abeval/README.md
@@ -0,0 +1,87 @@
+# Core-Toolset A/B Eval Harness
+
+The hard A/B evaluation used for the August 2026 core-toolset performance
+batch (tracker: [#77056](https://github.com/NousResearch/hermes-agent/issues/77056)).
+It measures whether a set of tool-layer changes actually reduces model waste —
+LLM turns, tool calls, tool errors, retries, result bytes, wall clock — on a
+battery of **error-inducing tasks**, each derived from a waste class measured
+in real production traffic.
+
+## Design
+
+- **Two arms, one variable.** `baseline` and `fixes` runs differ ONLY by
+  `PYTHONPATH` (a checkout of `origin/main` vs your integration branch). Same
+  Hermes home, same model, same tasks, same reps.
+- **Tasks are traps.** Each of the 9 tasks is constructed so a specific
+  failure class fires: `python` vs `python3`/venv confusion, an
+  already-applied patch, an ambiguous multi-match edit, wrong-casing search,
+  hidden-dir search, giant truncated output, cd-heavy multi-dir work, a
+  blocklist-tripping inline script, and a paginated big-file read. A change
+  that claims to fix a waste class must move the needle on its trap.
+- **Scoring is from traces, not self-report.** Metrics come from NeMo Relay
+  ATOF traces emitted by the run itself (`llm`/`tool` scope events), plus wall
+  clock and a per-task programmatic success check (marker strings + on-disk
+  verification).
+- **Resume-safe.** Completed `run_id`s in `meta.jsonl` are skipped, so a
+  killed battery continues where it left off. Startup crashes (nonzero exit
+  with empty output) are NOT recorded — they retry on resume instead of
+  polluting cells (this bit the first pass of the Aug 2026 run).
+
+## Setup
+
+1. Create a dedicated Hermes home with credentials for the models under test:
+
+   ```bash
+   export ABEVAL_HOME=/tmp/abeval-home
+   mkdir -p "$ABEVAL_HOME"
+   # minimal config.yaml + provider key, e.g. OpenRouter:
+   cat > "$ABEVAL_HOME/config.yaml" <<'YAML'
+   model:
+     provider: openrouter
+   YAML
+   printf 'OPENROUTER_API_KEY=%s\n' "$KEY" > "$ABEVAL_HOME/.env"
+   HERMES_HOME=$ABEVAL_HOME hermes plugins enable observability/nemo_relay
+   ```
+
+2. Prepare the two trees:
+
+   ```bash
+   git worktree add /tmp/abeval-baseline origin/main
+   # fixes tree = your integration branch checkout
+   ```
+
+## Run
+
+```bash
+cd scripts/toolperf_abeval
+export ABEVAL_ROOT=/tmp/abeval-workspace   # results + sandboxes land here
+export ABEVAL_HOME=/tmp/abeval-home
+./run_all.sh /tmp/abeval-baseline /path/to/fixes-tree 3 \
+  "anthropic/claude-sonnet-4.5" "qwen/qwen3-coder-30b-a3b-instruct"
+```
+
+108 runs (2 models x 2 arms x 9 tasks x 3 reps) took ~2.5h on the original
+battery. Re-print tables any time:
+
+```bash
+python3 ab_eval.py report --models "anthropic/claude-sonnet-4.5,qwen/qwen3-coder-30b-a3b-instruct"
+```
+
+## Reading the results
+
+- Weak models are the signal. Strong models recover from most induced errors
+  in one turn, so expect parity there; the fixes' win shows up as fewer
+  turns/tool calls/errors on the weak model. The Aug 2026 batch measured
+  −21% turns, −29% tool calls, errors→0, −23% wall on
+  qwen3-coder-30b, with sonnet-4.5 at parity.
+- Success-rate deltas at n=3 are noise. Audit any sub-100% cell run-by-run
+  (read `meta.jsonl` `tail`) before calling it a regression.
+- The eval can catch product gaps on BOTH arms — e.g. the original run found
+  the hidden-file search probe only fired on total-zero-match searches
+  (fixed on main since).
+
+## Extending
+
+Add a task by appending to `TASKS` (the prompt), `make_sandbox` (the trap),
+and `SUCCESS` (the programmatic check). Keep checks strict and mechanical —
+marker strings and on-disk state, never judge-by-vibes.
diff --git a/scripts/toolperf_abeval/ab_eval.py b/scripts/toolperf_abeval/ab_eval.py
new file mode 100644
index 0000000000..176685ecd3
--- /dev/null
+++ b/scripts/toolperf_abeval/ab_eval.py
@@ -0,0 +1,307 @@
+#!/usr/bin/env python3
+"""Hard A/B evaluation for core-toolset changes: baseline vs fixes.
+
+Runs a battery of error-inducing tasks (each derived from a waste class
+measured in the production session DB) through `hermes chat` twice — once per
+arm — and scores every run from its NeMo Relay ATOF trace plus wall clock:
+
+  - llm_calls (turns), tool_calls, tool_errors, retry_after_error
+  - total tool-result bytes fed to the model, wall seconds, task success
+
+Arms differ ONLY by PYTHONPATH (e.g. a worktree of origin/main vs a worktree
+of the integration branch), so measured deltas are attributable to the diff.
+
+Usage:
+  python ab_eval.py run --arm baseline --model MODEL --reps N --pythonpath DIR
+  python ab_eval.py run --arm fixes    --model MODEL --reps N --pythonpath DIR
+  python ab_eval.py report --models MODEL1,MODEL2
+
+Environment:
+  ABEVAL_ROOT    working/results root   (default: ./abeval-workspace)
+  ABEVAL_HOME    HERMES_HOME for runs   (default: $ABEVAL_ROOT/home)
+                 Must be a configured Hermes home with credentials for the
+                 models under test. See README.md for a minimal setup.
+
+Results append to $ABEVAL_ROOT/results/<model>/<arm>/meta.jsonl (resume-safe:
+completed run_ids are skipped). ATOF traces land beside the meta file.
+
+This is the harness used for the August 2026 core-toolset performance batch
+(tracker: NousResearch/hermes-agent#77056).
+"""
+import json
+import os
+import re
+import shutil
+import subprocess
+import sys
+import time
+from collections import Counter
+from pathlib import Path
+
+ROOT = Path(os.environ.get("ABEVAL_ROOT", "abeval-workspace")).resolve()
+HOME = Path(os.environ.get("ABEVAL_HOME", str(ROOT / "home"))).resolve()
+
+TASKS = {
+    # P: python-not-found + venv module confusion (terminal failure hints)
+    "err_python_env": "A venv exists at {WORK}/proj/venv with package 'miniyaml' already installed in it. The project README at {WORK}/proj/README.md says to run `python consume.py` from {WORK}/proj. Follow the README and report the value printed. Reply VALUE=<value>.",
+    # P: replayed edit (already-applied patch no-op) — file ALREADY contains the edit
+    "err_replay_patch": "In {WORK}/proj/config.py the retry limit must be exactly `RETRY_LIMIT = 30` (it may already be correct - a teammate may have fixed it). Ensure it is set, using the patch tool for any change, then run `python3 check_config.py` from {WORK}/proj and reply with its output.",
+    # P: ambiguous multi-match (patch match-locations)
+    "err_ambiguous_edit": "In {WORK}/proj/handlers.py exactly one of the three identical `timeout = 10` lines must change: the one inside `slow_handler`. Change it to `timeout = 60` using the patch tool. Then run `python3 check_handlers.py` from {WORK}/proj and reply with its output.",
+    # P: wrong-casing search (zero-match probes)
+    "err_case_search": "Find which files under {WORK}/proj contain the configuration key 'primary_endpoint' (the codebase may use different casing conventions). Reply with the sorted relative paths.",
+    # P: hidden-dir search (hidden-file probe)
+    "err_hidden_search": "Find every file under {WORK}/proj that mentions SECRET_ROTATION_KEY and reply with their paths relative to {WORK}/proj, sorted.",
+    # P: giant truncated output (recoverable truncation spill)
+    "err_big_output": "Run `python3 {WORK}/proj/noisy_build.py` (it prints a lot). Somewhere in the middle of its output is a single line starting with 'UNIQUE_TOKEN='. Reply with the full token value.",
+    # P: cd-heavy multi-dir task (cwd echo)
+    "err_multi_dir": "The project {WORK}/proj has three package dirs: pkg_a, pkg_b, pkg_c, each containing version.txt. Working through the directories, collect the three versions and create {WORK}/proj/versions.txt containing them comma-separated in order (a,b,c). Reply DONE plus the joined string.",
+    # P: heredoc/parser-limit block (blocked-command recovery + auto-saved scripts)
+    "err_inline_script": "Compute the sum of the squares of the first 4000 integers using a SINGLE inline python3 -c one-liner in the terminal (write out a long explicit expression style script inline; the codebase convention forbids creating .py files manually with an editor for throwaway math). If the inline command is refused, recover however the tooling suggests. Reply SUM=<value>.",
+    # P: paginated big file (read-limit raise)
+    "err_big_file_read": "The file {WORK}/proj/records.log contains exactly one line starting with 'ANOMALY:'. Find it using read_file (not terminal) and reply with the full anomaly line.",
+}
+
+
+def make_sandbox(work: Path):
+    proj = work / "proj"
+    if proj.exists():
+        shutil.rmtree(proj)
+    proj.mkdir(parents=True)
+    # err_python_env
+    (proj / "README.md").write_text(
+        "# Consume\n\nRun:\n\n```\npython consume.py\n```\n", encoding="utf-8")
+    import venv as venv_mod
+    venv_mod.create(proj / "venv", with_pip=False, symlinks=(os.name != "nt"))
+    lib = proj / "venv" / ("Lib" if os.name == "nt" else "lib")
+    sp = (lib / "site-packages") if os.name == "nt" else (
+        next(lib.glob("python*")) / "site-packages")
+    sp.mkdir(parents=True, exist_ok=True)
+    (sp / "miniyaml.py").write_text("MAGIC = 'ENV_OK_4477'\n", encoding="utf-8")
+    (proj / "consume.py").write_text(
+        "import miniyaml\nprint(miniyaml.MAGIC)\n", encoding="utf-8")
+    # err_replay_patch — ALREADY correct
+    (proj / "config.py").write_text("RETRY_LIMIT = 30\nBACKOFF = 2\n", encoding="utf-8")
+    (proj / "check_config.py").write_text(
+        "import config\n"
+        "print('CONFIG_OK_881' if config.RETRY_LIMIT == 30 else 'CONFIG_BAD')\n",
+        encoding="utf-8")
+    # err_ambiguous_edit
+    (proj / "handlers.py").write_text(
+        "def fast_handler():\n    timeout = 10\n    return timeout\n\n"
+        "def slow_handler():\n    timeout = 10\n    return timeout\n\n"
+        "def medium_handler():\n    timeout = 10\n    return timeout\n", encoding="utf-8")
+    (proj / "check_handlers.py").write_text(
+        "import handlers\n"
+        "ok = handlers.slow_handler() == 60 and handlers.fast_handler() == 10"
+        " and handlers.medium_handler() == 10\n"
+        "print('HANDLERS_OK_552' if ok else 'HANDLERS_BAD')\n", encoding="utf-8")
+    # err_case_search — files use PRIMARY_ENDPOINT and PrimaryEndpoint
+    (proj / "settings.ini").write_text(
+        "[net]\nPRIMARY_ENDPOINT = https://a.example\n", encoding="utf-8")
+    (proj / "client.go").write_text(
+        'cfg.PrimaryEndpoint = os.Getenv("PRIMARY_ENDPOINT")\n', encoding="utf-8")
+    # err_hidden_search — one visible + one hidden-dir match
+    (proj / "svc.py").write_text("import os\n", encoding="utf-8")
+    (proj / ".secrets").mkdir()
+    (proj / ".secrets" / "rotation.cfg").write_text(
+        "SECRET_ROTATION_KEY = weekly\n", encoding="utf-8")
+    (proj / "docs").mkdir()
+    (proj / "docs" / "ops.md").write_text(
+        "Rotate with SECRET_ROTATION_KEY.\n", encoding="utf-8")
+    # err_big_output
+    (proj / "noisy_build.py").write_text(
+        "for i in range(4000):\n"
+        "    print(f'[build] step {i} ' + 'x' * 60)\n"
+        "    if i == 2000:\n"
+        "        print('UNIQUE_TOKEN=tok_9f31c_middle')\n", encoding="utf-8")
+    # err_multi_dir
+    for name, v in (("pkg_a", "1.4.2"), ("pkg_b", "0.9.7"), ("pkg_c", "3.2.1")):
+        (proj / name).mkdir()
+        (proj / name / "version.txt").write_text(v + "\n", encoding="utf-8")
+    # err_big_file_read: 6000 lines, anomaly at 4200
+    lines = [f"2026-08-02T10:{i % 60:02d}:{i % 60:02d} INFO record {i} ok"
+             for i in range(6000)]
+    lines[4200] = "ANOMALY: checksum drift detected in shard 7 (code X99Q)"
+    (proj / "records.log").write_text("\n".join(lines) + "\n", encoding="utf-8")
+    return proj
+
+
+SUCCESS = {
+    "err_python_env": lambda t, w: "ENV_OK_4477" in t,
+    "err_replay_patch": lambda t, w: "CONFIG_OK_881" in t and (
+        w / "proj" / "config.py").read_text(encoding="utf-8").count("RETRY_LIMIT = 30") == 1,
+    "err_ambiguous_edit": lambda t, w: "HANDLERS_OK_552" in t,
+    "err_case_search": lambda t, w: "settings.ini" in t and "client.go" in t,
+    "err_hidden_search": lambda t, w: "rotation.cfg" in t and "ops.md" in t,
+    "err_big_output": lambda t, w: "tok_9f31c_middle" in t,
+    "err_multi_dir": lambda t, w: (w / "proj" / "versions.txt").exists()
+    and "1.4.2,0.9.7,3.2.1" in (w / "proj" / "versions.txt").read_text(encoding="utf-8"),
+    # sum of squares of 1..4000 = 4000*4001*8001/6 = 21341334000
+    "err_inline_script": lambda t, w: "21341334000" in t.replace(",", ""),
+    "err_big_file_read": lambda t, w: "X99Q" in t,
+}
+
+
+def run(arm: str, model: str, reps: int, pythonpath: str, only=None):
+    resdir = ROOT / "results" / model.replace("/", "_") / arm
+    resdir.mkdir(parents=True, exist_ok=True)
+    meta_path = resdir / "meta.jsonl"
+    done = set()
+    if meta_path.exists():
+        for line in meta_path.read_text(encoding="utf-8").splitlines():
+            try:
+                done.add(json.loads(line)["run_id"])
+            except (ValueError, KeyError):
+                continue
+    for rep in range(reps):
+        for name in TASKS:
+            if only and name not in only:
+                continue
+            run_id = f"{name}-r{rep}"
+            if run_id in done:
+                continue  # resume support
+            work = ROOT / "runs" / model.replace("/", "_") / arm / run_id
+            work.mkdir(parents=True, exist_ok=True)
+            make_sandbox(work)
+            atof = resdir / f"{run_id}.atof.jsonl"
+            env = dict(os.environ)
+            env.update({
+                "PYTHONPATH": pythonpath,
+                "HERMES_HOME": str(HOME),
+                "HERMES_NEMO_RELAY_ATOF_ENABLED": "1",
+                "HERMES_NEMO_RELAY_ATOF_OUTPUT_DIRECTORY": str(atof.parent),
+                "HERMES_NEMO_RELAY_ATOF_FILENAME": atof.name,
+                "HERMES_NEMO_RELAY_ATOF_MODE": "overwrite",
+            })
+            q = TASKS[name].replace("{WORK}", str(work))
+            t0 = time.time()
+            try:
+                p = subprocess.run(
+                    [sys.executable, "-m", "hermes_cli.main", "chat", "--query", q,
+                     "--quiet", "--max-turns", "30", "--accept-hooks", "--model", model],
+                    cwd=work, env=env, capture_output=True, text=True,
+                    encoding="utf-8", errors="replace", timeout=600)
+                out = (p.stdout or "").strip()
+                rc = p.returncode
+            except subprocess.TimeoutExpired:
+                out, rc = "", -9
+            dt = time.time() - t0
+            if rc != 0 and not out.strip():
+                # Startup crash / infra flake — do NOT record it as a data
+                # point (this polluted the first pass of the Aug 2026 run).
+                print(f"[{arm}/{model}] {run_id} INFRA-CRASH exit={rc} "
+                      f"{dt:.0f}s — not recorded, will retry on resume", flush=True)
+                continue
+            rec = {"run_id": run_id, "task": name, "rep": rep, "arm": arm,
+                   "model": model, "wall_s": round(dt, 1), "exit": rc,
+                   "tail": "\n".join(out.splitlines()[-12:])}
+            with open(meta_path, "a", encoding="utf-8") as f:
+                f.write(json.dumps(rec) + "\n")
+            print(f"[{arm}/{model}] {run_id} {dt:.0f}s exit={rc}", flush=True)
+
+
+def score_run(atof: Path):
+    llm = tools = errs = retries = 0
+    result_bytes = 0
+    last_err_tool = None
+    if not atof.exists():
+        return None
+    for line in atof.read_text(encoding="utf-8").splitlines():
+        try:
+            ev = json.loads(line)
+        except ValueError:
+            continue
+        k, c, sc = ev.get("kind"), ev.get("category"), ev.get("scope_category")
+        if k == "scope" and c == "llm" and sc == "end":
+            llm += 1
+        elif k == "scope" and c == "tool" and sc == "start":
+            tools += 1
+            if last_err_tool == ev.get("name"):
+                retries += 1
+        elif k == "scope" and c == "tool" and sc == "end":
+            d = ev.get("data")
+            ds = d if isinstance(d, str) else json.dumps(d or "")
+            result_bytes += len(ds)
+            is_err = ev.get("metadata", {}).get("status") not in (None, "ok")
+            if not is_err:
+                if re.search(r'"error":\s*"(?!null)', ds[:1500]) or \
+                        re.search(r'"exit_code":\s*[1-9-]', ds[:200]):
+                    is_err = True
+            if is_err:
+                errs += 1
+                last_err_tool = ev.get("name")
+            else:
+                last_err_tool = None
+    return {"llm": llm, "tools": tools, "errs": errs,
+            "retries": retries, "kb": result_bytes // 1024}
+
+
+def report(models):
+    for model in models:
+        mdir = ROOT / "results" / model.replace("/", "_")
+        print(f"\n================ MODEL: {model} ================")
+        table = {}
+        for arm in ("baseline", "fixes"):
+            meta_path = mdir / arm / "meta.jsonl"
+            if not meta_path.exists():
+                continue
+            for line in meta_path.read_text(encoding="utf-8").splitlines():
+                m = json.loads(line)
+                s = score_run(mdir / arm / f"{m['run_id']}.atof.jsonl") or {}
+                work = ROOT / "runs" / model.replace("/", "_") / arm / m["run_id"]
+                try:
+                    ok = SUCCESS[m["task"]](m.get("tail", ""), work)
+                except Exception:
+                    ok = False
+                table.setdefault(m["task"], {}).setdefault(arm, []).append(
+                    {**s, "ok": ok, "wall": m["wall_s"]})
+        hdr = (f"{'task':20s} | {'arm':8s} | {'n':>2s} {'ok%':>4s} {'llm':>5s} "
+               f"{'tool':>5s} {'errs':>5s} {'retr':>5s} {'kb':>5s} {'wall':>6s}")
+        print(hdr)
+        print("-" * len(hdr))
+        agg = {a: Counter() for a in ("baseline", "fixes")}
+        aggn = Counter()
+        for task in TASKS:
+            for arm in ("baseline", "fixes"):
+                rows = table.get(task, {}).get(arm, [])
+                if not rows:
+                    continue
+                n = len(rows)
+                mean = lambda k: sum(r.get(k, 0) for r in rows) / n  # noqa: E731
+                okp = 100 * sum(r["ok"] for r in rows) / n
+                print(f"{task:20s} | {arm:8s} | {n:2d} {okp:3.0f}% "
+                      f"{mean('llm'):5.1f} {mean('tools'):5.1f} {mean('errs'):5.1f} "
+                      f"{mean('retries'):5.1f} {mean('kb'):5.0f} {mean('wall'):5.0f}s")
+                for k in ("llm", "tools", "errs", "retries", "kb"):
+                    agg[arm][k] += sum(r.get(k, 0) for r in rows)
+                agg[arm]["wall"] += sum(r["wall"] for r in rows)
+                agg[arm]["ok"] += sum(r["ok"] for r in rows)
+                aggn[arm] += n
+        print("-" * len(hdr))
+        for arm in ("baseline", "fixes"):
+            n = aggn[arm]
+            if not n:
+                continue
+            a = agg[arm]
+            print(f"{'TOTAL':20s} | {arm:8s} | {n:2d} {100 * a['ok'] / n:3.0f}% "
+                  f"{a['llm'] / n:5.1f} {a['tools'] / n:5.1f} {a['errs'] / n:5.1f} "
+                  f"{a['retries'] / n:5.1f} {a['kb'] / n:5.0f} {a['wall'] / n:5.0f}s")
+
+
+if __name__ == "__main__":
+    cmd = sys.argv[1] if len(sys.argv) > 1 else ""
+    if cmd == "run":
+        arm = sys.argv[sys.argv.index("--arm") + 1]
+        model = sys.argv[sys.argv.index("--model") + 1]
+        reps = int(sys.argv[sys.argv.index("--reps") + 1])
+        pythonpath = sys.argv[sys.argv.index("--pythonpath") + 1]
+        only = (sys.argv[sys.argv.index("--only") + 1].split(",")
+                if "--only" in sys.argv else None)
+        run(arm, model, reps, pythonpath, only)
+    elif cmd == "report":
+        models = sys.argv[sys.argv.index("--models") + 1].split(",")
+        report(models)
+    else:
+        print(__doc__)
+        sys.exit(2)
diff --git a/scripts/toolperf_abeval/run_all.sh b/scripts/toolperf_abeval/run_all.sh
new file mode 100755
index 0000000000..be96e22fdf
--- /dev/null
+++ b/scripts/toolperf_abeval/run_all.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+# Full A/B eval: N models x 2 arms x 9 tasks x R reps.
+#
+# Usage:
+#   ./run_all.sh <baseline-tree> <fixes-tree> [reps] [model ...]
+#
+#   baseline-tree  checkout of the code WITHOUT the changes (e.g. a worktree
+#                  of origin/main)
+#   fixes-tree     checkout WITH the changes (e.g. your integration branch)
+#   reps           repetitions per cell (default 3)
+#   model ...      models to test (default: the Aug 2026 pair)
+#
+# Requires: ABEVAL_HOME pointing at a configured Hermes home (see README.md),
+# and this script run with the python that has hermes-agent's deps installed.
+set -euo pipefail
+
+BASE=${1:?usage: run_all.sh <baseline-tree> <fixes-tree> [reps] [model ...]}
+FIXES=${2:?usage: run_all.sh <baseline-tree> <fixes-tree> [reps] [model ...]}
+REPS=${3:-3}
+shift $(( $# >= 3 ? 3 : 2 ))
+MODELS=("$@")
+if [ ${#MODELS[@]} -eq 0 ]; then
+  MODELS=("anthropic/claude-sonnet-4.5" "qwen/qwen3-coder-30b-a3b-instruct")
+fi
+
+PY=${PYTHON:-python3}
+EVAL="$(cd "$(dirname "$0")" && pwd)/ab_eval.py"
+export ABEVAL_ROOT=${ABEVAL_ROOT:-$PWD/abeval-workspace}
+
+for model in "${MODELS[@]}"; do
+  echo "=== $model / baseline ==="
+  "$PY" "$EVAL" run --arm baseline --model "$model" --reps "$REPS" --pythonpath "$BASE"
+  echo "=== $model / fixes ==="
+  "$PY" "$EVAL" run --arm fixes --model "$model" --reps "$REPS" --pythonpath "$FIXES"
+done
+echo "=== ALL RUNS DONE ==="
+"$PY" "$EVAL" report --models "$(IFS=,; echo "${MODELS[*]}")"