diff --git a/ml/experiments/bench/README.md b/ml/experiments/bench/README.md
new file mode 100644
index 0000000..c08fb48
--- /dev/null
+++ b/ml/experiments/bench/README.md
@@ -0,0 +1,89 @@
+# `bench/` — combined model + prompt evaluation harness
+
+Combines the work of issues **#93** (model benchmark) and **#95** (prompt
+A/B) into one MLflow-tracked experiment. Each evaluation cell is one
+``(model × prompt_version × scenario)`` triple; we vary models and prompt
+versions on the same fixed scenario set so quality differences are
+attributable rather than confounded.
+
+## Pieces
+
+| File | Purpose |
+|------|---------|
+| `rubric.md`         | The scoring rubric (`tip-v1`). Anchor for the human judge across sessions. |
+| `scenarios.py`      | Deterministic ``(persona × time-slot × tasks)`` contexts; same input across all cells. |
+| `mlflow_client.py`  | Thin httpx-based MLflow REST wrapper. Handles the local ``--allowed-hosts`` quirk and the file-only artifact backend. |
+| `collect.py`        | **Phase A.** Generates candidates per cell, logs MLflow runs with `judge_pending=true`. |
+| `judge_cli.py`      | **Phase B.** `--export` pulls pending runs into one JSON file; the Claude Code session fills in scores; `--apply` writes them back. |
+| `compare.py`        | **Phase C.** Leaderboard per ``(model, prompt)`` cell. |
+
+## RAM safety (#93 hard requirement)
+
+* Models > 4B are **rejected up front** by `collect.py --max-model-b 4.0`.
+* Calls to Ollama include ``keep_alive=0``, which unloads the model from
+  VRAM as soon as the response returns. We never hold two LLM weights
+  concurrently.
+* No mock/embedded judges hold weights either: the human judge is the
+  Claude Code session, RAM cost zero.
+
+The pipeline can run on a 15 GiB / 8 GiB-VRAM box (1070-class GPU) end
+to end without paging.
+
+## Quick start
+
+```bash
+# 1. Generate candidates for the (model × prompt) grid
+python ml/experiments/bench/collect.py \
+    --models qwen2.5:0.5b,qwen2.5:1.5b,gemma3:1b,llama3.2:3b \
+    --prompts v1,v2-mentor,v3-few-shot \
+    --experiment tip-bench-2026-04-27 \
+    --n-tips 5 \
+    --diversity
+
+# 2. Export pending runs for Claude Code to score
+python ml/experiments/bench/judge_cli.py \
+    --experiment tip-bench-2026-04-27 \
+    --export /tmp/oo-bench-judge.json
+
+# 3. (Claude Code edits /tmp/oo-bench-judge.json, fills scores per rubric.md.)
+
+# 4. Push scores back to MLflow
+python ml/experiments/bench/judge_cli.py \
+    --experiment tip-bench-2026-04-27 \
+    --apply /tmp/oo-bench-judge.json
+
+# 5. Leaderboard
+python ml/experiments/bench/compare.py --experiment tip-bench-2026-04-27
+```
+
+## Why the rubric matters
+
+Different judging sessions need to be comparable. `rubric.md` pins down
+what ``relevance=4`` means with calibrated examples, so a tip scored 4
+today is equivalent to a tip scored 4 next week. Without the rubric, the
+"lazy human-in-the-loop" judge drifts.
+
+## Accessing results in MLflow
+
+Each run's quality scores (relevance, actionability, tone, composite) are
+stored as **metrics** on the MLflow run — accessible via:
+
+1. **MLflow UI**: experiment `tip-bench-2026-04-27` → click any run → **Metrics** section
+2. **Leaderboard**: `python ml/experiments/bench/compare.py --experiment tip-bench-2026-04-27`
+3. **Raw API**: `mlflow_client.search_runs()` filters and pulls metrics in bulk
+
+Candidate tips, prompts, and raw responses are stored as **tags** with
+keys `artifact:candidates.json`, `artifact:prompt.txt`, `artifact:raw.txt`
+(tag fallback because the MLflow server uses a file:// artifact backend
+not accessible via REST from the host).
+
+## Integrating with Airflow (#95)
+
+A future DAG `ml/pipelines/prompt_ab_eval.py` will wrap `collect.py`
+exactly as shown in the quick-start, triggered on-demand from the admin
+UI or manually. The results feed into the admin leaderboard view.
+
+For now, the pipeline is runnable standalone on any machine with:
+- Ollama models ≤4B
+- MLflow tracking server
+- Python 3.10+
diff --git a/ml/experiments/bench/__init__.py b/ml/experiments/bench/__init__.py
new file mode 100644
index 0000000..824ea95
--- /dev/null
+++ b/ml/experiments/bench/__init__.py
@@ -0,0 +1,18 @@
+"""oO tip-generation benchmark harness.
+
+Combines model evaluation (#93) and prompt A/B testing (#95) into one
+MLflow-tracked experiment. Each evaluation cell is one (model × prompt ×
+scenario) triple; we vary models and prompts on the same fixed scenario
+set so quality differences are attributable rather than confounded.
+
+The pipeline follows the lazy-judge pattern: collect candidates with
+deterministic metrics (latency, format_ok), export to a JSON file for
+Claude Code to score per the rubric, apply scores back to MLflow, and
+generate a leaderboard.
+
+RAM safety is enforced: models >4B are rejected, Ollama calls use
+keep_alive=0 to unload VRAM immediately, and the human judge (Claude Code
+session) has zero inference cost.
+
+See README.md for usage.
+"""
diff --git a/ml/experiments/bench/collect.py b/ml/experiments/bench/collect.py
new file mode 100644
index 0000000..2e68928
--- /dev/null
+++ b/ml/experiments/bench/collect.py
@@ -0,0 +1,338 @@
+"""Phase A — collect tip candidates per (model × prompt × scenario) cell.
+
+Each cell produces one MLflow run with:
+
+  params:   model, prompt_version, scenario_id, persona, hour_of_day,
+            n_tips_requested, temperature
+  tags:     judge_pending=true, judge_kind=claude-code, rubric=tip-v1
+  metrics:  latency_ms, prompt_tokens (best effort), completion_tokens,
+            n_parsed, format_ok, mean_diversity (cosine, optional)
+  artifacts (as tags via mlflow_client.log_text):
+            prompt.txt          system + user prompt as sent
+            candidates.json     parsed candidate array
+            raw.txt             the model's raw response (for triage)
+
+Models are called **sequentially** with ``keep_alive=0`` so Ollama unloads
+the previous model from VRAM before loading the next — keeps the box
+within RAM/VRAM budget. Models > 4B are rejected up front.
+
+Usage:
+
+    python collect.py \\
+        --models qwen2.5:0.5b,qwen2.5:1.5b,gemma3:1b,llama3.2:3b \\
+        --prompts v1,v2-mentor,v3-few-shot \\
+        --n-tips 5 \\
+        --experiment tip-bench-2026-04-27
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import math
+import os
+import re
+import sys
+import time
+from dataclasses import asdict
+from pathlib import Path
+
+import httpx
+
+_BENCH = Path(__file__).resolve().parent
+_ML = _BENCH.parent.parent
+sys.path.insert(0, str(_BENCH))
+sys.path.insert(0, str(_BENCH.parent / "sim"))
+sys.path.insert(0, str(_ML / "serving"))
+
+from mlflow_client import MLflowClient  # type: ignore
+from prompts import get_prompt, PROMPTS  # type: ignore
+from scenarios import build_scenarios  # type: ignore
+
+
+# Hard cap mirrors the issue #93 comment: "don't use models larger than 4b
+# locally because of RAM limits". A regex cheap-match on the tag handles
+# the common ``name:Nb`` and ``name:N.Mb`` forms; anything that doesn't
+# match the pattern is allowed (cloud aliases, embeddings, etc.).
+_SIZE_TAG = re.compile(r":(\d+(?:\.\d+)?)b\b", re.IGNORECASE)
+
+
+def _model_too_big(model: str, max_b: float = 4.0) -> bool:
+    m = _SIZE_TAG.search(model)
+    if not m:
+        return False
+    return float(m.group(1)) > max_b
+
+
+def _parse_json_array(raw: str) -> list[dict] | None:
+    """Best-effort parse — strip markdown fences, then ``json.loads``."""
+    text = raw.strip()
+    if text.startswith("```"):
+        parts = text.split("```")
+        text = parts[1] if len(parts) > 1 else text
+        if text.lstrip().lower().startswith("json"):
+            text = text.lstrip()[4:]
+    # Sometimes models prefix with garbage — try to slice from the first ``[``.
+    if not text.lstrip().startswith("["):
+        i = text.find("[")
+        if i >= 0:
+            text = text[i:]
+    try:
+        v = json.loads(text)
+        return v if isinstance(v, list) else None
+    except (json.JSONDecodeError, ValueError):
+        return None
+
+
+def _embed(text: str, ollama_url: str) -> list[float] | None:
+    """Use nomic-embed-text via Ollama for diversity scoring. ~250MB,
+    safe to load alongside any 4B chat model thanks to ``keep_alive=0``.
+    """
+    try:
+        with httpx.Client(trust_env=False, timeout=30.0) as c:
+            r = c.post(
+                f"{ollama_url}/api/embeddings",
+                json={"model": "nomic-embed-text", "prompt": text, "keep_alive": 0},
+            )
+            r.raise_for_status()
+            return r.json().get("embedding")
+    except Exception:
+        return None
+
+
+def _mean_pairwise_cosine(vecs: list[list[float]]) -> float:
+    if len(vecs) < 2:
+        return 0.0
+
+    def cos(a: list[float], b: list[float]) -> float:
+        na = math.sqrt(sum(x * x for x in a))
+        nb = math.sqrt(sum(x * x for x in b))
+        if na == 0 or nb == 0:
+            return 0.0
+        return sum(x * y for x, y in zip(a, b)) / (na * nb)
+
+    n = len(vecs)
+    total, count = 0.0, 0
+    for i in range(n):
+        for j in range(i + 1, n):
+            total += cos(vecs[i], vecs[j])
+            count += 1
+    return total / count if count else 0.0
+
+
+def _call_ollama(
+    *,
+    model: str,
+    system: str,
+    user: str,
+    ollama_url: str,
+    temperature: float = 0.7,
+) -> tuple[str, dict]:
+    """Direct call to Ollama. Returns (raw_text, telemetry).
+
+    ``keep_alive=0`` is the key RAM-safety lever: the model is unloaded
+    immediately after the response. The next model in the loop loads
+    fresh, so we never hold two models in VRAM at once.
+    """
+    t0 = time.perf_counter()
+    body = {
+        "model": model,
+        "messages": [
+            {"role": "system", "content": system},
+            {"role": "user", "content": user},
+        ],
+        "stream": False,
+        "keep_alive": 0,
+        "options": {"temperature": temperature},
+    }
+    with httpx.Client(trust_env=False, timeout=180.0) as c:
+        r = c.post(f"{ollama_url}/api/chat", json=body)
+        r.raise_for_status()
+        data = r.json()
+    elapsed_ms = (time.perf_counter() - t0) * 1000.0
+    raw = data.get("message", {}).get("content", "")
+    telemetry = {
+        "latency_ms": elapsed_ms,
+        # Ollama exposes token counts at top-level of the response when
+        # ``stream=false``; missing on some older versions, hence the
+        # ``.get`` defaults.
+        "prompt_tokens": float(data.get("prompt_eval_count", 0) or 0),
+        "completion_tokens": float(data.get("eval_count", 0) or 0),
+    }
+    return raw, telemetry
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="oO tip-generation benchmark — Phase A")
+    parser.add_argument("--models", required=True,
+                        help="Comma-separated model tags (Ollama-side names).")
+    parser.add_argument("--prompts", default=",".join(PROMPTS.keys()),
+                        help="Comma-separated prompt versions from ml/serving/prompts.py.")
+    parser.add_argument("--experiment", default="tip-bench-v1",
+                        help="MLflow experiment name.")
+    parser.add_argument("--n-tips", type=int, default=5,
+                        help="Tips to request per scenario.")
+    parser.add_argument("--temperature", type=float, default=0.7)
+    parser.add_argument("--ollama-url", default=os.environ.get("OLLAMA_URL", "http://localhost:11434"))
+    parser.add_argument("--mlflow-url", default=os.environ.get("MLFLOW_TRACKING_URI", "http://localhost:5000"))
+    parser.add_argument("--diversity", action="store_true",
+                        help="Embed each candidate for cosine-diversity metric (~+1s/call).")
+    parser.add_argument("--max-model-b", type=float, default=4.0,
+                        help="Reject models tagged larger than this many billion params.")
+    parser.add_argument("--n-scenarios", type=int, default=0,
+                        help="Cap scenario count (0 = use all from scenarios.py).")
+    parser.add_argument("--rubric", default=str(_BENCH / "rubric.md"),
+                        help="Rubric file logged once per experiment.")
+    args = parser.parse_args()
+
+    models = [m.strip() for m in args.models.split(",") if m.strip()]
+    prompts = [p.strip() for p in args.prompts.split(",") if p.strip()]
+    too_big = [m for m in models if _model_too_big(m, args.max_model_b)]
+    if too_big:
+        print(f"ERROR: models exceed --max-model-b={args.max_model_b}: {too_big}", file=sys.stderr)
+        return 2
+    unknown_prompts = [p for p in prompts if p not in PROMPTS]
+    if unknown_prompts:
+        print(f"ERROR: unknown prompt versions: {unknown_prompts}. "
+              f"Available: {list(PROMPTS)}", file=sys.stderr)
+        return 2
+
+    scenarios = build_scenarios()
+    if args.n_scenarios and args.n_scenarios < len(scenarios):
+        scenarios = scenarios[:args.n_scenarios]
+    n_cells = len(models) * len(prompts) * len(scenarios)
+    print(f"Models    : {models}")
+    print(f"Prompts   : {prompts}")
+    print(f"Scenarios : {len(scenarios)}")
+    print(f"Cells     : {n_cells}  ({len(models)} × {len(prompts)} × {len(scenarios)})")
+    print()
+
+    client = MLflowClient(
+        tracking_uri=args.mlflow_url,
+        username=os.environ.get("MLFLOW_TRACKING_USERNAME") or "admin",
+        password=os.environ.get("MLFLOW_TRACKING_PASSWORD") or "password",
+    )
+    exp_id = client.get_or_create_experiment(args.experiment)
+    print(f"MLflow experiment: {args.experiment}  (id={exp_id})")
+
+    rubric_text = Path(args.rubric).read_text(encoding="utf-8")
+
+    # Outer loop is *model* so each model loads once-per-pass instead of
+    # once-per-cell. With ``keep_alive=0`` that's 1 load per (model ×
+    # scenario × prompt) but Ollama caches recently-touched models for
+    # the duration of a single HTTP burst — practically each model is
+    # warm-loaded throughout its sub-loop.
+    cell_idx = 0
+    for model in models:
+        print(f"── model {model} ──")
+        for prompt_v in prompts:
+            prompt = get_prompt(prompt_v)
+            for sc in scenarios:
+                cell_idx += 1
+                ctx = sc.to_prompt_context()
+
+                class _Ctx:
+                    pass
+                _ctx = _Ctx()
+                _ctx.tasks = ctx["tasks"]
+                _ctx.hour_of_day = ctx["hour_of_day"]
+                _ctx.day_of_week = ctx["day_of_week"]
+                _ctx.extra = ctx["extra"]
+                user_msg = prompt.build_user(_ctx, args.n_tips)
+
+                run_id = client.create_run(
+                    exp_id,
+                    run_name=f"{model}__{prompt_v}__{sc.id}",
+                    tags={
+                        "judge_pending": "true",
+                        "judge_kind": "claude-code",
+                        "rubric": "tip-v1",
+                        "model": model,
+                        "prompt_version": prompt_v,
+                        "scenario_id": sc.id,
+                        "persona": sc.persona.name,
+                    },
+                )
+                client.log_params(run_id, {
+                    "model": model,
+                    "prompt_version": prompt_v,
+                    "scenario_id": sc.id,
+                    "persona": sc.persona.name,
+                    "hour_of_day": sc.hour_of_day,
+                    "day_of_week": sc.day_of_week,
+                    "n_tips_requested": args.n_tips,
+                    "temperature": args.temperature,
+                })
+
+                try:
+                    raw, telemetry = _call_ollama(
+                        model=model,
+                        system=prompt.system,
+                        user=user_msg,
+                        ollama_url=args.ollama_url,
+                        temperature=args.temperature,
+                    )
+                except Exception as e:
+                    print(f"  [{cell_idx}/{n_cells}] {model} {prompt_v} {sc.id}: ERROR {e}")
+                    client.set_tag(run_id, "error", str(e)[:500])
+                    client.end_run(run_id, status="FAILED")
+                    continue
+
+                items = _parse_json_array(raw)
+                format_ok = 1.0 if items is not None else 0.0
+                items = items or []
+
+                # Filter to dict-shaped items only (some models return string lists).
+                cand_dicts = [
+                    {
+                        "id": str(it.get("id", f"tip-{i}")),
+                        "content": str(it.get("content", "")),
+                        "rationale": str(it.get("rationale", "")),
+                    }
+                    for i, it in enumerate(items)
+                    if isinstance(it, dict)
+                ]
+                n_parsed = float(len(cand_dicts))
+
+                metrics = {
+                    "latency_ms": telemetry["latency_ms"],
+                    "prompt_tokens": telemetry["prompt_tokens"],
+                    "completion_tokens": telemetry["completion_tokens"],
+                    "n_parsed": n_parsed,
+                    "format_ok": format_ok,
+                }
+
+                if args.diversity and len(cand_dicts) >= 2:
+                    embs = []
+                    for c in cand_dicts:
+                        e = _embed(c["content"], args.ollama_url)
+                        if e:
+                            embs.append(e)
+                    if len(embs) >= 2:
+                        # Cosine *similarity* — lower means more diverse, so
+                        # we report ``mean_diversity = 1 - sim``.
+                        sim = _mean_pairwise_cosine(embs)
+                        metrics["mean_diversity"] = 1.0 - sim
+
+                client.log_metrics(run_id, metrics)
+                client.log_text(run_id, prompt.system + "\n\n---\n\n" + user_msg, "prompt.txt")
+                client.log_text(run_id, json.dumps(cand_dicts, indent=2), "candidates.json")
+                client.log_text(run_id, raw[:9_000], "raw.txt")
+                # Persist the rubric exactly once per experiment as a parameter
+                # of every run — cheap, but means every run is self-describing.
+                client.set_tag(run_id, "rubric_md", rubric_text[: client._TAG_VALUE_LIMIT])
+
+                client.end_run(run_id)
+                print(f"  [{cell_idx:>3}/{n_cells}] {model:18s} {prompt_v:12s} {sc.id:24s}  "
+                      f"lat={metrics['latency_ms']:>6.0f}ms  parsed={int(n_parsed)}/{args.n_tips}  "
+                      f"fmt={int(format_ok)}")
+
+    print()
+    print(f"Phase A complete. Run judge_cli.py --export to score pending runs.")
+    print(f"  python ml/experiments/bench/judge_cli.py --experiment {args.experiment} \\")
+    print(f"      --export /tmp/oo-bench-judge-requests.json")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/ml/experiments/bench/compare.py b/ml/experiments/bench/compare.py
new file mode 100644
index 0000000..bec3751
--- /dev/null
+++ b/ml/experiments/bench/compare.py
@@ -0,0 +1,144 @@
+"""Phase C — leaderboard from judged MLflow runs.
+
+Pulls every judged run (``judge_pending=false`` or any run with the
+composite metric set) from the experiment, groups by (model, prompt)
+cell, and prints a leaderboard sorted by mean composite score.
+
+Also reports the deterministic-only metrics (latency, format_ok) so
+cells with great prose but broken JSON are visible.
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import statistics
+import sys
+from collections import defaultdict
+from pathlib import Path
+
+_BENCH = Path(__file__).resolve().parent
+sys.path.insert(0, str(_BENCH))
+from mlflow_client import MLflowClient  # type: ignore
+
+
+def _params(run: dict) -> dict[str, str]:
+    return {p["key"]: p["value"] for p in run["data"].get("params", [])}
+
+
+def _metrics(run: dict) -> dict[str, float]:
+    return {m["key"]: m["value"] for m in run["data"].get("metrics", [])}
+
+
+def _tags(run: dict) -> dict[str, str]:
+    return {t["key"]: t["value"] for t in run["data"].get("tags", [])}
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="oO bench — Phase C (leaderboard)")
+    parser.add_argument("--experiment", required=True)
+    parser.add_argument("--mlflow-url", default=os.environ.get("MLFLOW_TRACKING_URI", "http://localhost:5000"))
+    parser.add_argument("--include-pending", action="store_true",
+                        help="Also include rows with no quality scores (latency/format only).")
+    args = parser.parse_args()
+
+    client = MLflowClient(
+        tracking_uri=args.mlflow_url,
+        username=os.environ.get("MLFLOW_TRACKING_USERNAME") or "admin",
+        password=os.environ.get("MLFLOW_TRACKING_PASSWORD") or "password",
+    )
+    exp_id = client.get_or_create_experiment(args.experiment)
+    runs = client.search_runs(exp_id, max_results=2000)
+
+    # Group key = (model, prompt_version)
+    cells: dict[tuple[str, str], list[dict]] = defaultdict(list)
+    for r in runs:
+        params = _params(r)
+        metrics = _metrics(r)
+        tags = _tags(r)
+        if r["info"].get("status") != "FINISHED":
+            continue
+        if not args.include_pending and "composite" not in metrics:
+            continue
+        cells[(params.get("model", "?"), params.get("prompt_version", "?"))].append({
+            "metrics": metrics,
+            "scenario": params.get("scenario_id", "?"),
+            "judged": tags.get("judge_pending") == "false",
+        })
+
+    if not cells:
+        print("No judged runs found. Did you run judge_cli.py --apply?")
+        return 1
+
+    rows = []
+    for (model, prompt), records in cells.items():
+        n = len(records)
+        comp = [r["metrics"]["composite"] for r in records if "composite" in r["metrics"]]
+        rel  = [r["metrics"]["relevance"] for r in records if "relevance" in r["metrics"]]
+        act  = [r["metrics"]["actionability"] for r in records if "actionability" in r["metrics"]]
+        tone = [r["metrics"]["tone"] for r in records if "tone" in r["metrics"]]
+        lat  = [r["metrics"]["latency_ms"] for r in records if "latency_ms" in r["metrics"]]
+        fmt  = [r["metrics"]["format_ok"] for r in records if "format_ok" in r["metrics"]]
+        div  = [r["metrics"]["mean_diversity"] for r in records if "mean_diversity" in r["metrics"]]
+
+        rows.append({
+            "model": model,
+            "prompt": prompt,
+            "n": n,
+            "composite": statistics.mean(comp) if comp else None,
+            "relevance": statistics.mean(rel) if rel else None,
+            "actionability": statistics.mean(act) if act else None,
+            "tone": statistics.mean(tone) if tone else None,
+            "format_ok": statistics.mean(fmt) if fmt else None,
+            "latency_p50": statistics.median(lat) if lat else None,
+            "latency_p95": _p95(lat) if lat else None,
+            "diversity": statistics.mean(div) if div else None,
+        })
+
+    rows.sort(key=lambda r: r["composite"] if r["composite"] is not None else -1, reverse=True)
+
+    # Width-fitted printer — keeps output legible in a 100-col terminal.
+    print()
+    print(f"Experiment: {args.experiment}  (id={exp_id})")
+    print(f"Cells     : {len(rows)}")
+    print()
+    header = (
+        f"{'#':>2}  {'model':18s} {'prompt':12s} {'n':>3s}  "
+        f"{'comp':>5s} {'rel':>4s} {'act':>4s} {'tone':>4s} "
+        f"{'fmt':>4s} {'p50':>6s} {'p95':>6s} {'div':>5s}"
+    )
+    print(header)
+    print("─" * len(header))
+    for i, r in enumerate(rows, 1):
+        comp = f"{r['composite']:.2f}" if r["composite"] is not None else "  -- "
+        rel  = f"{r['relevance']:.1f}" if r["relevance"] is not None else " -- "
+        act  = f"{r['actionability']:.1f}" if r["actionability"] is not None else " -- "
+        tone = f"{r['tone']:.1f}" if r["tone"] is not None else " -- "
+        fmt  = f"{r['format_ok']:.2f}" if r["format_ok"] is not None else " -- "
+        p50  = f"{r['latency_p50']:.0f}" if r["latency_p50"] is not None else "  --  "
+        p95  = f"{r['latency_p95']:.0f}" if r["latency_p95"] is not None else "  --  "
+        div  = f"{r['diversity']:.2f}" if r["diversity"] is not None else " -- "
+        print(
+            f"{i:>2}  {r['model']:18s} {r['prompt']:12s} {r['n']:>3d}  "
+            f"{comp:>5s} {rel:>4s} {act:>4s} {tone:>4s} "
+            f"{fmt:>4s} {p50:>6s} {p95:>6s} {div:>5s}"
+        )
+
+    if rows[0]["composite"] is not None:
+        winner = rows[0]
+        print()
+        print(f"Winner: {winner['model']} × {winner['prompt']}  "
+              f"(composite={winner['composite']:.2f}, n={winner['n']})")
+    return 0
+
+
+def _p95(xs: list[float]) -> float:
+    if not xs:
+        return 0.0
+    s = sorted(xs)
+    idx = max(0, int(round(0.95 * (len(s) - 1))))
+    return s[idx]
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/ml/experiments/bench/judge_cli.py b/ml/experiments/bench/judge_cli.py
new file mode 100644
index 0000000..fd809fe
--- /dev/null
+++ b/ml/experiments/bench/judge_cli.py
@@ -0,0 +1,191 @@
+"""Phase B — Claude Code as the lazy MLflow judge.
+
+Two sub-commands, both keyed to MLflow tags so the same run cycles
+through ``judge_pending=true`` → judged → ``judge_pending=false`` exactly
+once.
+
+  --export PATH
+      Pull every run with ``judge_pending=true`` and ``judge_kind=claude-code``
+      from the experiment, bundle the prompt + parsed candidates + the
+      rubric into a single JSON file the Claude Code session can read.
+
+  --apply PATH
+      Read the responses (same shape as the request, with ``scores`` filled in)
+      and log ``relevance``, ``actionability``, ``tone``, ``overlong`` as
+      MLflow metrics on the corresponding runs. Sets ``judge_pending=false``
+      and stamps ``judged_at`` / ``judged_by`` so the run won't be picked up
+      twice.
+
+The request file is intentionally one big JSON document, so the human
+judge sees the full set in one place and can score consistently.
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import sys
+import time
+from pathlib import Path
+
+_BENCH = Path(__file__).resolve().parent
+sys.path.insert(0, str(_BENCH))
+from mlflow_client import MLflowClient  # type: ignore
+
+
+_DIMENSIONS = ("relevance", "actionability", "tone")
+_BIN_FLAGS = ("overlong",)
+
+
+def _tags_dict(run: dict) -> dict[str, str]:
+    return {t["key"]: t["value"] for t in run.get("data", {}).get("tags", [])}
+
+
+def _params_dict(run: dict) -> dict[str, str]:
+    return {p["key"]: p["value"] for p in run.get("data", {}).get("params", [])}
+
+
+def export(client: MLflowClient, experiment: str, out_path: str) -> int:
+    exp_id = client.get_or_create_experiment(experiment)
+    runs = client.search_runs(
+        exp_id,
+        filter_string="tags.judge_pending = 'true' and tags.judge_kind = 'claude-code'",
+    )
+    if not runs:
+        print("No pending runs.")
+        Path(out_path).write_text(json.dumps({
+            "experiment": experiment,
+            "exported_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+            "rubric": "tip-v1",
+            "items": [],
+        }, indent=2))
+        return 0
+
+    rubric_text = (_BENCH / "rubric.md").read_text(encoding="utf-8")
+
+    items: list[dict] = []
+    for run in runs:
+        run_id = run["info"]["run_id"]
+        tags = _tags_dict(run)
+        params = _params_dict(run)
+        candidates_json = client.get_artifact_text(run_id, "candidates.json")
+        prompt_text = client.get_artifact_text(run_id, "prompt.txt")
+        try:
+            candidates = json.loads(candidates_json) if candidates_json else []
+        except json.JSONDecodeError:
+            candidates = []
+
+        items.append({
+            "run_id": run_id,
+            "model": params.get("model") or tags.get("model"),
+            "prompt_version": params.get("prompt_version") or tags.get("prompt_version"),
+            "scenario_id": params.get("scenario_id") or tags.get("scenario_id"),
+            "persona": params.get("persona") or tags.get("persona"),
+            "hour_of_day": int(params.get("hour_of_day", "12")),
+            "day_of_week": int(params.get("day_of_week", "0")),
+            "prompt": prompt_text,
+            "candidates": candidates,
+            # Per-run scoring slot — judge fills these in.
+            "scores": {
+                "relevance": None,        # 1–5, integer
+                "actionability": None,    # 1–5, integer
+                "tone": None,             # 1–5, integer
+                "overlong": None,         # 0/1
+                "notes": "",              # short comment, optional
+            },
+        })
+
+    out = {
+        "experiment": experiment,
+        "exported_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+        "rubric": "tip-v1",
+        "rubric_md": rubric_text,
+        "items": items,
+    }
+    Path(out_path).write_text(json.dumps(out, indent=2, ensure_ascii=False))
+    print(f"Exported {len(items)} pending runs → {out_path}")
+    return 0
+
+
+def apply(client: MLflowClient, experiment: str, in_path: str) -> int:
+    exp_id = client.get_or_create_experiment(experiment)
+    payload = json.loads(Path(in_path).read_text(encoding="utf-8"))
+    items = payload.get("items", [])
+    if not items:
+        print("No items in response file.")
+        return 0
+
+    judged_at = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
+    n_applied, n_skipped = 0, 0
+    for item in items:
+        run_id = item["run_id"]
+        scores = item.get("scores") or {}
+
+        missing = [d for d in _DIMENSIONS if scores.get(d) in (None, "")]
+        if missing:
+            print(f"  [skip] {run_id}: missing {missing}")
+            n_skipped += 1
+            continue
+
+        metrics = {d: float(scores[d]) for d in _DIMENSIONS}
+        for f in _BIN_FLAGS:
+            v = scores.get(f)
+            if v not in (None, ""):
+                metrics[f] = float(int(bool(int(v))))
+
+        # Composite mirrors rubric.md: relevance + actionability + tone
+        # + 2 * format_ok - overlong.  format_ok is already a metric on
+        # the run from collect.py; re-fetching is cheap and keeps this
+        # script idempotent if format compliance was retroactively fixed.
+        run = client._get("/runs/get", {"run_id": run_id})["run"]
+        existing_metrics = {m["key"]: m["value"] for m in run["data"].get("metrics", [])}
+        format_ok = float(existing_metrics.get("format_ok", 0.0))
+        overlong = metrics.get("overlong", 0.0)
+        composite = (
+            metrics["relevance"] + metrics["actionability"] + metrics["tone"]
+            + 2 * format_ok - overlong
+        )
+        metrics["composite"] = composite
+
+        client.log_metrics(run_id, metrics)
+        client.set_tags(run_id, {
+            "judge_pending": "false",
+            "judged_at": judged_at,
+            "judged_by": "claude-code-session",
+        })
+        if scores.get("notes"):
+            client.set_tag(run_id, "judge_notes", str(scores["notes"])[:1000])
+
+        n_applied += 1
+        print(f"  [ok]   {run_id}: rel={metrics['relevance']:.1f} "
+              f"act={metrics['actionability']:.1f} tone={metrics['tone']:.1f} "
+              f"comp={composite:.2f}")
+
+    print(f"Applied {n_applied}, skipped {n_skipped}.")
+    return 0
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="oO bench — Phase B (Claude Code judge)")
+    parser.add_argument("--experiment", required=True)
+    parser.add_argument("--mlflow-url", default=os.environ.get("MLFLOW_TRACKING_URI", "http://localhost:5000"))
+    grp = parser.add_mutually_exclusive_group(required=True)
+    grp.add_argument("--export", metavar="PATH",
+                     help="Write pending runs as a judgment-request JSON file.")
+    grp.add_argument("--apply", metavar="PATH",
+                     help="Read filled-in responses and write metrics back to MLflow.")
+    args = parser.parse_args()
+
+    client = MLflowClient(
+        tracking_uri=args.mlflow_url,
+        username=os.environ.get("MLFLOW_TRACKING_USERNAME") or "admin",
+        password=os.environ.get("MLFLOW_TRACKING_PASSWORD") or "password",
+    )
+    if args.export:
+        return export(client, args.experiment, args.export)
+    return apply(client, args.experiment, args.apply)
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/ml/experiments/bench/mlflow_client.py b/ml/experiments/bench/mlflow_client.py
new file mode 100644
index 0000000..9eaa2ac
--- /dev/null
+++ b/ml/experiments/bench/mlflow_client.py
@@ -0,0 +1,202 @@
+"""Thin MLflow REST wrapper.
+
+Why not the official ``mlflow`` SDK? Two reasons specific to the oO setup:
+
+1. The MLflow server (3.11) ships with ``--allowed-hosts localhost`` but
+   curl / requests / urllib3 send ``Host: localhost:5000`` — the port
+   suffix fails the DNS-rebinding check. We override the Host header per
+   request, which the SDK doesn't expose.
+2. The collect/judge phases only need ~6 endpoints (create/search/log).
+   Pulling a 200MB SDK transitively for that is excess weight.
+
+All calls are synchronous httpx with explicit ``Host`` so the script can
+run from the host shell, from inside docker, or from Airflow workers
+without further config.
+"""
+
+from __future__ import annotations
+
+import os
+import time
+from dataclasses import dataclass
+from typing import Any
+
+import httpx
+
+
+def _strip_path(uri: str) -> tuple[str, str]:
+    """Return (origin, path_prefix) — handles both /mlflow and / roots.
+
+    ``http://mlflow:5000/mlflow``  → ("http://mlflow:5000", "/mlflow")
+    ``http://localhost:5000``      → ("http://localhost:5000", "")
+    """
+    uri = uri.rstrip("/")
+    if "/" not in uri.split("://", 1)[1]:
+        return uri, ""
+    scheme_host, _, rest = uri.partition("://")
+    host, _, path = rest.partition("/")
+    return f"{scheme_host}://{host}", "/" + path if path else ""
+
+
+@dataclass
+class MLflowClient:
+    tracking_uri: str
+    username: str | None = None
+    password: str | None = None
+    host_header: str | None = None  # override for DNS-rebinding sidestep
+    timeout: float = 30.0
+
+    def __post_init__(self) -> None:
+        self._origin, self._ui_prefix = _strip_path(self.tracking_uri)
+        # MLflow 3.x exposes the REST API at the root, *not* under the
+        # ``/mlflow`` UI prefix. Empirically verified against the running
+        # ghcr.io/mlflow/mlflow:v3.11.1 container.
+        self._api = f"{self._origin}/api/2.0/mlflow"
+        self._auth = (self.username, self.password) if self.username else None
+        # If user did not pass a host header, derive from origin. Strip
+        # the port if present — the server's allowed-hosts check rejects
+        # ``localhost:5000`` even when ``localhost`` is allowed.
+        if self.host_header is None:
+            host = self._origin.split("://", 1)[1]
+            self.host_header = host.split(":", 1)[0]
+
+    @classmethod
+    def from_env(cls) -> "MLflowClient":
+        return cls(
+            tracking_uri=os.environ.get("MLFLOW_TRACKING_URI", "http://localhost:5000"),
+            username=os.environ.get("MLFLOW_TRACKING_USERNAME") or "admin",
+            password=os.environ.get("MLFLOW_TRACKING_PASSWORD") or "password",
+            host_header=os.environ.get("MLFLOW_HOST_HEADER"),
+        )
+
+    def _headers(self) -> dict[str, str]:
+        return {"Host": self.host_header or "localhost"}
+
+    def _post(self, path: str, body: dict) -> dict:
+        with httpx.Client(trust_env=False, timeout=self.timeout) as c:
+            r = c.post(f"{self._api}{path}", json=body, headers=self._headers(), auth=self._auth)
+            r.raise_for_status()
+            return r.json()
+
+    def _get(self, path: str, params: dict | None = None) -> dict:
+        with httpx.Client(trust_env=False, timeout=self.timeout) as c:
+            r = c.get(f"{self._api}{path}", params=params or {}, headers=self._headers(), auth=self._auth)
+            r.raise_for_status()
+            return r.json()
+
+    # ── Experiments ────────────────────────────────────────────────────
+
+    def get_or_create_experiment(self, name: str) -> str:
+        try:
+            r = self._get("/experiments/get-by-name", {"experiment_name": name})
+            return r["experiment"]["experiment_id"]
+        except httpx.HTTPStatusError as e:
+            if e.response.status_code not in (404, 400):
+                raise
+        r = self._post("/experiments/create", {"name": name})
+        return r["experiment_id"]
+
+    # ── Runs ───────────────────────────────────────────────────────────
+
+    def create_run(
+        self,
+        experiment_id: str,
+        run_name: str,
+        tags: dict[str, str] | None = None,
+    ) -> str:
+        body: dict[str, Any] = {
+            "experiment_id": experiment_id,
+            "start_time": int(time.time() * 1000),
+            "run_name": run_name,
+            "tags": [
+                {"key": k, "value": str(v)}
+                for k, v in (tags or {}).items()
+            ],
+        }
+        r = self._post("/runs/create", body)
+        return r["run"]["info"]["run_id"]
+
+    def log_param(self, run_id: str, key: str, value: Any) -> None:
+        self._post("/runs/log-parameter", {"run_id": run_id, "key": key, "value": str(value)})
+
+    def log_params(self, run_id: str, params: dict[str, Any]) -> None:
+        for k, v in params.items():
+            self.log_param(run_id, k, v)
+
+    def log_metric(self, run_id: str, key: str, value: float, step: int = 0) -> None:
+        self._post("/runs/log-metric", {
+            "run_id": run_id,
+            "key": key,
+            "value": float(value),
+            "timestamp": int(time.time() * 1000),
+            "step": step,
+        })
+
+    def log_metrics(self, run_id: str, metrics: dict[str, float]) -> None:
+        for k, v in metrics.items():
+            self.log_metric(run_id, k, v)
+
+    def set_tag(self, run_id: str, key: str, value: str) -> None:
+        self._post("/runs/set-tag", {"run_id": run_id, "key": key, "value": str(value)})
+
+    def set_tags(self, run_id: str, tags: dict[str, str]) -> None:
+        for k, v in tags.items():
+            self.set_tag(run_id, k, v)
+
+    # MLflow tag values are capped at 5000 chars by the server (RESOURCE_DOES_NOT_EXIST
+    # below that, INVALID_PARAMETER_VALUE above). 4500 leaves headroom for
+    # internal metadata MLflow may append on its own.
+    _TAG_VALUE_LIMIT = 4500
+
+    def log_text(self, run_id: str, text: str, artifact_path: str) -> None:
+        """Persist short text alongside the run.
+
+        The MLflow server in this deployment uses a ``file://`` artifact
+        backend, which is only reachable from inside the container — not
+        via the REST proxy. We instead stash short payloads as tags
+        keyed ``artifact:<path>``. Anything longer than 4500 chars is
+        chunked into ``artifact:<path>:0``, ``:1`` …; ``get_artifact_text``
+        re-stitches them in order.
+        """
+        key_base = f"artifact:{artifact_path}"
+        if len(text) <= self._TAG_VALUE_LIMIT:
+            self.set_tag(run_id, key_base, text)
+            return
+        # chunk
+        for i in range(0, len(text), self._TAG_VALUE_LIMIT):
+            self.set_tag(run_id, f"{key_base}:{i // self._TAG_VALUE_LIMIT}",
+                          text[i:i + self._TAG_VALUE_LIMIT])
+
+    def get_artifact_text(self, run_id: str, artifact_path: str) -> str:
+        run = self._get("/runs/get", {"run_id": run_id})["run"]
+        tags = {t["key"]: t["value"] for t in run["data"].get("tags", [])}
+        key_base = f"artifact:{artifact_path}"
+        if key_base in tags:
+            return tags[key_base]
+        # chunked form
+        chunks = sorted(
+            (k for k in tags if k.startswith(f"{key_base}:")),
+            key=lambda k: int(k.rsplit(":", 1)[1]),
+        )
+        return "".join(tags[k] for k in chunks)
+
+    def end_run(self, run_id: str, status: str = "FINISHED") -> None:
+        self._post("/runs/update", {
+            "run_id": run_id,
+            "status": status,
+            "end_time": int(time.time() * 1000),
+        })
+
+    def search_runs(
+        self,
+        experiment_id: str,
+        filter_string: str = "",
+        max_results: int = 1000,
+    ) -> list[dict]:
+        body = {
+            "experiment_ids": [experiment_id],
+            "filter": filter_string,
+            "max_results": max_results,
+        }
+        r = self._post("/runs/search", body)
+        return r.get("runs", [])
diff --git a/ml/experiments/bench/rubric.md b/ml/experiments/bench/rubric.md
new file mode 100644
index 0000000..633c09b
--- /dev/null
+++ b/ml/experiments/bench/rubric.md
@@ -0,0 +1,85 @@
+# Tip-quality rubric — `tip-v1`
+
+This file is the consistency anchor for the Claude Code judge. The same
+rubric is used across every judging session so verdicts are comparable
+across runs (per the lazy-judge pattern in #95).
+
+Each candidate tip is scored on three independent 1–5 dimensions, plus
+two binary flags. Score the **content of the tip itself** for the given
+persona/context — do not score the rationale.
+
+## Dimensions
+
+### relevance — 1 to 5
+How well does the tip respond to *this specific persona at this specific
+time*? A generic productivity platitude is 1; a tip that hooks into the
+persona's stated preferences and the actual hour-of-day is 5.
+
+| score | description |
+|-------|-------------|
+| 1 | Boilerplate. Could apply to any user, any time. |
+| 2 | Vaguely fits the persona but ignores context. |
+| 3 | Fits the persona OR the time, not both. |
+| 4 | Fits both persona and time, with one specific anchor (a task, an hour, a habit). |
+| 5 | Specific to the persona's preferences AND respects the hour, with a clear hook into a candidate task or routine. |
+
+### actionability — 1 to 5
+Could the user *do this in the next 10 minutes* without further planning?
+"Try to focus more" is 1; "Spend 12 minutes on the Call dentist task and
+stop when the timer ends" is 5.
+
+| score | description |
+|-------|-------------|
+| 1 | Pure encouragement, no action. |
+| 2 | Action exists but vague ("review your tasks"). |
+| 3 | Concrete verb + object, but missing the time/duration handle. |
+| 4 | Concrete action with a duration or trigger ("for 10 minutes", "before lunch"). |
+| 5 | Micro-action with explicit start, duration, and a stop condition. |
+
+### tone — 1 to 5
+Does the tip sound like a calm, specific mentor (the product voice) or
+like a generic chatbot/coach? Penalize emoji-spam, exclamation marks,
+hype words ("amazing!", "let's crush it!"), and corporate jargon.
+
+| score | description |
+|-------|-------------|
+| 1 | Hype, jargon, or motivational-poster tone. |
+| 2 | Polite chatbot tone, no warmth. |
+| 3 | Neutral, businesslike. |
+| 4 | Quiet and specific, like a coach who knows you. |
+| 5 | Earned. Reads like a mentor who has seen this exact stuck-pattern before. |
+
+## Binary flags
+
+### format_ok — 0 or 1
+1 if the *whole response* parsed as a JSON array of objects with the
+required keys (`id`, `content`, `rationale`). 0 otherwise. **This is
+computed automatically by `collect.py`** — judges should not override it.
+
+### overlong — 0 or 1
+1 if `content` exceeds the documented 2-sentence cap (count sentence-
+ending punctuation `. ! ?`). Judges may flag this as a tiebreaker.
+
+## Composite score
+
+`compare.py` ranks cells by:
+
+```
+composite = relevance + actionability + tone + 2*format_ok - overlong
+```
+
+i.e. format compliance is a doubled weight (a malformed JSON is a hard
+production failure regardless of how good the prose is).
+
+## Calibration examples
+
+(Shared with judges so a 4 means the same thing across sessions.)
+
+**Persona**: deadline-driven (responds to overdue/high-priority,
+morning-active). **Hour**: 09:00. **Tasks include**: an overdue
+"Call dentist", priority 4.
+
+- "Stay focused and make today count!" — relevance 1, actionability 1, tone 1.
+- "Review your tasks and pick one that matters." — relevance 2, actionability 2, tone 3.
+- "Spend the next 12 minutes on Call dentist — set a timer and stop when it rings." — relevance 5, actionability 5, tone 4.
+- "It's 09:00 — you respond to overdue items best now. Block 12 minutes for Call dentist before your first meeting." — relevance 5, actionability 5, tone 5.
diff --git a/ml/experiments/bench/scenarios.py b/ml/experiments/bench/scenarios.py
new file mode 100644
index 0000000..35947b5
--- /dev/null
+++ b/ml/experiments/bench/scenarios.py
@@ -0,0 +1,80 @@
+"""Fixed contexts for the tip-generation benchmark.
+
+Every cell of the (model × prompt) grid is evaluated on the *same* set of
+scenarios so quality differences are attributable to the model/prompt,
+not to context variance.
+
+A scenario is one (persona, hour-of-day, candidate-task-pool) tuple. The
+hour and the task pool are seeded deterministically from the persona's
+name so the bench is reproducible across machines.
+"""
+
+from __future__ import annotations
+
+import sys
+from dataclasses import dataclass
+from pathlib import Path
+
+# Reuse personas from sim — same source of truth for user archetypes.
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "sim"))
+from personas import PERSONAS, Persona  # type: ignore
+from task_generator import generate_task_pool  # type: ignore
+
+
+@dataclass(frozen=True)
+class Scenario:
+    id: str           # stable id used as MLflow tag — keep ASCII safe
+    persona: Persona
+    hour_of_day: int  # 0–23
+    day_of_week: int  # 0=Mon
+    tasks: list[dict]
+
+    def to_prompt_context(self) -> dict:
+        """Shape expected by ml/serving/prompts.PromptContext."""
+        return {
+            "tasks": [
+                {
+                    "content": t["content"],
+                    "priority": t["features"]["priority"],
+                    "is_overdue": t["features"]["is_overdue"],
+                    "due_date": t.get("due_date", "no due date"),
+                }
+                for t in self.tasks
+            ],
+            "hour_of_day": self.hour_of_day,
+            "day_of_week": self.day_of_week,
+            "extra": {
+                "persona": self.persona.name,
+                "persona_hint": self.persona.description,
+            },
+        }
+
+
+# Two time-slots probe whether the model adapts its tone to the hour.
+# Morning (09) and evening (21) are picked because most personas have
+# strong directional preferences there.
+_TIME_SLOTS = [(9, 1), (21, 3)]   # (hour_of_day, day_of_week)
+
+
+def build_scenarios(tasks_per_scenario: int = 6) -> list[Scenario]:
+    """Return a deterministic list of scenarios.
+
+    With 4 personas × 2 time-slots = 8 scenarios. Task pools are seeded
+    by ``hash(persona.name) + hour`` so runs are reproducible and each
+    persona sees the same tasks at the same hour across cells.
+    """
+    out: list[Scenario] = []
+    for persona in PERSONAS[:4]:
+        for hour, dow in _TIME_SLOTS:
+            seed = (abs(hash(persona.name)) % 9973) + hour
+            tasks = generate_task_pool(n=tasks_per_scenario, seed=seed)
+            out.append(
+                Scenario(
+                    id=f"{persona.name}-h{hour:02d}",
+                    persona=persona,
+                    hour_of_day=hour,
+                    day_of_week=dow,
+                    tasks=tasks,
+                )
+            )
+    return out