feat: ε-greedy v1 as active policy; dwell-time reward inference; offline sim framework

- Promote egreedy-v1 to active serving policy (ADR-0007): /score/egreedy + /reward/egreedy
  replaces linucb-v1 endpoints after offline sim shows +10.7% mean reward (−0.548 vs −0.606)
- Replace explicit helpful/not_helpful feedback with dwell-time inferred reward (inferReward):
  dismiss=−1.0, snooze=+0.1, done<15s=−0.3, done 15s–2min=+1.0, done 2–10min=+0.6, done>10min=+0.3
- Add ml/serving ε-greedy endpoints: /score/egreedy, /reward/egreedy, /stats/egreedy/{user_id}
  with d=7 feature vector (base 5 + sin/cos day-of-week encoding)
- Add offline simulation framework (ml/experiments/sim): rule/LLM/claude-code judges,
  two-phase score+reward, synthetic personas, task generator; results stored in sim_runs/sim_events
- Add /admin/simulations page: start runs, live-poll status, reward curve SVG, action/persona tables
- Fix egreedy day_of_week training skew: reward endpoint now uses actual dow instead of hardcoded 0
- Fix runner.py proxy bypass: httpx.Client(trust_env=False) for localhost ML calls
- Add dwellMs to TipFeedbackEvent contract and bus.test.ts fixture
- Schema: sim_runs, sim_events tables; tip_feedback gains dwell_ms, reward_milli columns
- ADR-0006: admin console framework; ADR-0007: egreedy-v1 policy selection rationale

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ml/experiments/sim/llm_judge.py

@@ -0,0 +1,204 @@
+"""
+LLM-based user reaction judge.
+
+Uses Claude Haiku when ANTHROPIC_API_KEY is set; falls back to a
+deterministic persona-based rule when it is not.
+"""
+
+from __future__ import annotations
+
+import os
+import random
+
+from personas import Persona
+
+ACTIONS = ["done", "snooze", "dismiss"]
+
+# Reward is NOT a fixed map anymore — it depends on action + simulated dwell time.
+# Use infer_reward() to compute the final reward after simulating dwell.
+_BASE_REWARDS: dict[str, float] = {
+    "done": 1.0,   # placeholder; real reward computed from dwell
+    "snooze": 0.1,
+    "dismiss": -1.0,
+}
+
+
+def infer_reward(action: str, dwell_ms: int) -> float:
+    """Mirror of production inferReward() in recommender.ts."""
+    if action == "dismiss":
+        return -1.0
+    if action == "snooze":
+        return 0.1
+    # done — dwell-based
+    if dwell_ms < 15_000:
+        return -0.3   # stale / reflex done
+    if dwell_ms < 120_000:
+        return 1.0    # magic zone
+    if dwell_ms < 600_000:
+        return 0.6    # good
+    return 0.3        # eventually done
+
+_HOUR_PERIODS = {
+    (5, 10): "morning",
+    (10, 14): "midday",
+    (14, 18): "afternoon",
+    (18, 22): "evening",
+}
+
+
+def _period(hour: int) -> str:
+    for (lo, hi), name in _HOUR_PERIODS.items():
+        if lo <= hour < hi:
+            return name
+    return "night"
+
+
+# ── Deterministic judge ────────────────────────────────────────────────────
+
+def _engagement_score(persona: Persona, tip: dict, hour: int) -> float:
+    """0–1 score of how well this tip fits this persona right now."""
+    features = tip.get("features", {})
+    priority = features.get("priority", 1)
+    is_overdue = features.get("is_overdue", False)
+
+    p = 0.35
+    priority_norm = (priority - 1) / 3.0
+    p += (priority_norm - 0.5) * persona.prefers_high_priority * 0.4
+    if is_overdue:
+        p += (persona.prefers_overdue - 0.5) * 0.3
+
+    is_morning = 5 <= hour < 10
+    is_evening = 18 <= hour < 22
+    if persona.morning_active and is_morning:
+        p += 0.15
+    elif persona.evening_active and is_evening:
+        p += 0.15
+    elif persona.morning_active and not is_morning and not is_evening:
+        p -= 0.10
+    elif persona.evening_active and not is_evening and not is_morning:
+        p -= 0.10
+
+    return max(0.05, min(0.90, p))
+
+
+def _simulate_dwell_ms(engagement: float, rng: random.Random) -> int:
+    """
+    Simulate how many milliseconds the user takes to act on a tip.
+
+    High engagement → quick action (magic zone, 15s–2min).
+    Medium engagement → slower (2–10min).
+    Low engagement → very slow (>10min) — tip helped eventually but not 'magic'.
+    For snooze/dismiss the dwell doesn't affect reward; return a short value.
+    """
+    if engagement >= 0.70:
+        # Strong match — magic zone: 15s–90s
+        return rng.randint(15_000, 90_000)
+    elif engagement >= 0.50:
+        # Moderate match — good zone: 2–8min
+        return rng.randint(120_000, 480_000)
+    else:
+        # Weak match but still done — eventually: 10–30min
+        return rng.randint(600_000, 1_800_000)
+
+
+def _rule_judge(persona: Persona, tip: dict, hour: int, rng: random.Random) -> tuple[str, int]:
+    """Return (action, dwell_ms) based on persona preferences and task features."""
+    engagement = _engagement_score(persona, tip, hour)
+
+    r = rng.random()
+    if r < engagement * 0.55:
+        # done — dwell depends on engagement
+        dwell = _simulate_dwell_ms(engagement, rng)
+        return "done", dwell
+    elif r < engagement:
+        return "snooze", rng.randint(3_000, 20_000)
+    else:
+        return "dismiss", rng.randint(1_000, 5_000)
+
+
+# ── LLM judge ─────────────────────────────────────────────────────────────
+
+_anthropic_client = None
+
+def _get_client():
+    global _anthropic_client
+    if _anthropic_client is None:
+        try:
+            import anthropic  # type: ignore
+            key = os.environ.get("ANTHROPIC_API_KEY", "")
+            if key:
+                _anthropic_client = anthropic.Anthropic(api_key=key)
+        except ImportError:
+            pass
+    return _anthropic_client
+
+
+def _llm_judge(
+    persona: Persona, tip: dict, hour: int, day_of_week: int, rng: random.Random,
+) -> tuple[str, int]:
+    client = _get_client()
+    if client is None:
+        return _rule_judge(persona, tip, hour, rng)
+
+    features = tip.get("features", {})
+    priority = features.get("priority", 1)
+    is_overdue = features.get("is_overdue", False)
+    age_days = features.get("task_age_days", 0)
+
+    priority_label = {1: "low", 2: "normal", 3: "high", 4: "urgent"}.get(priority, "normal")
+    overdue_str = f", overdue by {age_days:.0f} day(s)" if is_overdue else ""
+    days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
+    day_str = days[day_of_week % 7]
+
+    prompt = (
+        f"You are simulating how a specific user reacts to a task recommendation app.\n\n"
+        f"User persona: {persona.name}\n"
+        f"Persona: {persona.description}\n\n"
+        f'Recommended task: "{tip.get("content", "Unknown task")}"\n'
+        f"Task: priority={priority_label}{overdue_str}\n"
+        f"Current time: {_period(hour)} ({hour}:00, {day_str})\n\n"
+        f"How does this user react? Reply with exactly one word: done | snooze | dismiss\n\n"
+        f"- done: acts on this tip (marks task complete)\n"
+        f"- snooze: acknowledges but not now\n"
+        f"- dismiss: ignores or rejects it"
+    )
+
+    try:
+        message = client.messages.create(
+            model="claude-haiku-4-5-20251001",
+            max_tokens=10,
+            messages=[{"role": "user", "content": prompt}],
+        )
+        raw = message.content[0].text.strip().lower().split()[0]
+        action = raw if raw in ACTIONS else _rule_judge(persona, tip, hour, rng)[0]
+    except Exception:
+        action, _ = _rule_judge(persona, tip, hour, rng)
+
+    # Simulate dwell based on engagement level
+    engagement = _engagement_score(persona, tip, hour)
+    dwell = _simulate_dwell_ms(engagement, rng) if action == "done" else rng.randint(2_000, 15_000)
+    return action, dwell
+
+
+# ── Public API ─────────────────────────────────────────────────────────────
+
+def judge(
+    persona: Persona,
+    tip: dict,
+    hour: int,
+    day_of_week: int,
+    rng: random.Random,
+    use_llm: bool = True,
+) -> tuple[str, int, float]:
+    """Return (action, dwell_ms, reward).
+
+    action   — 'done' | 'snooze' | 'dismiss'
+    dwell_ms — simulated milliseconds between tip appearance and user action
+    reward   — inferred from action + dwell_ms via infer_reward()
+    """
+    if use_llm and os.environ.get("ANTHROPIC_API_KEY"):
+        action, dwell_ms = _llm_judge(persona, tip, hour, day_of_week, rng)
+    else:
+        action, dwell_ms = _rule_judge(persona, tip, hour, rng)
+
+    return action, dwell_ms, infer_reward(action, dwell_ms)

ml/experiments/sim/personas.py

@@ -0,0 +1,79 @@
+"""Synthetic user personas for simulation."""
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Persona:
+    name: str
+    description: str
+    # Feature preference weights — used by deterministic judge
+    prefers_high_priority: float  # 0–1: scales response to priority
+    prefers_overdue: float        # 0–1: scales response to overdue tasks
+    morning_active: bool          # higher engagement hours 6–10
+    evening_active: bool          # higher engagement hours 18–22
+    recency_bias: float           # 0–1: prefers recently-due tasks
+
+
+PERSONAS: list[Persona] = [
+    Persona(
+        name="deadline-driven",
+        description=(
+            "Responds urgently to overdue and high-priority tasks. "
+            "Most active in the morning. Dismisses low-priority tips."
+        ),
+        prefers_high_priority=0.9,
+        prefers_overdue=0.85,
+        morning_active=True,
+        evening_active=False,
+        recency_bias=0.3,
+    ),
+    Persona(
+        name="evening-relaxed",
+        description=(
+            "Reviews tasks in the evenings. Neutral on priority. "
+            "Snoozes morning recommendations."
+        ),
+        prefers_high_priority=0.5,
+        prefers_overdue=0.4,
+        morning_active=False,
+        evening_active=True,
+        recency_bias=0.5,
+    ),
+    Persona(
+        name="low-priority-first",
+        description=(
+            "Clears small tasks first. Snoozes urgent items until deadline. "
+            "Morning person."
+        ),
+        prefers_high_priority=0.2,
+        prefers_overdue=0.6,
+        morning_active=True,
+        evening_active=False,
+        recency_bias=0.7,
+    ),
+    Persona(
+        name="consistent-responder",
+        description=(
+            "Engages consistently across hours and days. "
+            "Acts on helpful tips regardless of priority."
+        ),
+        prefers_high_priority=0.6,
+        prefers_overdue=0.6,
+        morning_active=True,
+        evening_active=True,
+        recency_bias=0.5,
+    ),
+    Persona(
+        name="overdue-ignorer",
+        description=(
+            "Avoids overdue tasks (stress avoidance). "
+            "Focuses on future-due, high-priority items. Evening person."
+        ),
+        prefers_high_priority=0.8,
+        prefers_overdue=0.1,
+        morning_active=False,
+        evening_active=True,
+        recency_bias=0.2,
+    ),
+]

ml/experiments/sim/runner.py

@@ -0,0 +1,527 @@
+"""
+oO simulation runner — compares two recommendation policies.
+
+Judge modes:
+  rule         Deterministic persona-based rules (default, no external deps)
+  llm          Claude Haiku via Anthropic API (requires ANTHROPIC_API_KEY)
+  claude-code  Two-phase: Claude Code acts as the judge (you are the judge)
+
+Usage — rule/llm (single pass):
+  python runner.py --n-users 5 --n-rounds 10 --no-llm
+  python runner.py --n-users 5 --n-rounds 10
+
+Usage — claude-code judge (two phases):
+  # Phase 1: score candidates, write judgment requests
+  python runner.py --judge claude-code --phase score \\
+      --n-users 5 --n-rounds 10 --out /tmp/oo-cc-sim.json
+
+  # (Claude Code reads /tmp/oo-cc-sim-requests.json and writes /tmp/oo-cc-sim-responses.json)
+
+  # Phase 2: apply responses, run rewards, produce results
+  python runner.py --judge claude-code --phase reward --plan /tmp/oo-cc-sim-plan.json \\
+      --out /tmp/oo-cc-sim.json
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import random
+import sys
+import time
+import uuid
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent))
+
+import httpx
+
+from llm_judge import ACTIONS, infer_reward, judge
+from personas import PERSONAS, Persona
+from task_generator import generate_task_pool
+
+POLICY_SCORE_ENDPOINTS: dict[str, str] = {
+    "linucb-v1": "/score",
+    "egreedy-v1": "/score/egreedy",
+}
+POLICY_REWARD_ENDPOINTS: dict[str, str] = {
+    "linucb-v1": "/reward",
+    "egreedy-v1": "/reward/egreedy",
+}
+
+
+def _call_score(
+    client: httpx.Client, ml_url: str, policy: str,
+    user_id: str, tasks: list[dict], hour: int, dow: int,
+) -> dict | None:
+    endpoint = POLICY_SCORE_ENDPOINTS.get(policy, "/score")
+    body = {
+        "user_id": user_id,
+        "candidates": [
+            {
+                "id": t["id"], "content": t["content"], "source": t["source"],
+                "source_id": None,
+                "features": {
+                    "hour_of_day": hour,
+                    "is_overdue": t["features"]["is_overdue"],
+                    "task_age_days": t["features"]["task_age_days"],
+                    "priority": t["features"]["priority"],
+                },
+            }
+            for t in tasks
+        ],
+        "context": {"hour_of_day": hour, "day_of_week": dow},
+    }
+    try:
+        r = client.post(f"{ml_url}{endpoint}", json=body, timeout=5.0)
+        r.raise_for_status()
+        return r.json()
+    except Exception as e:
+        print(f"  [warn] score {policy}: {e}", file=sys.stderr)
+        return None
+
+
+def _call_reward(
+    client: httpx.Client, ml_url: str, policy: str,
+    user_id: str, tip_id: str, reward: float, features: dict,
+    day_of_week: int = 0,
+) -> None:
+    endpoint = POLICY_REWARD_ENDPOINTS.get(policy, "/reward")
+    try:
+        client.post(
+            f"{ml_url}{endpoint}",
+            json={"user_id": user_id, "tip_id": tip_id, "reward": reward,
+                  "features": features, "day_of_week": day_of_week},
+            timeout=5.0,
+        )
+    except Exception as e:
+        print(f"  [warn] reward {policy}: {e}", file=sys.stderr)
+
+
+# ── Standard single-pass runner (rule / llm modes) ─────────────────────────
+
+def run_simulation(
+    n_users: int, n_rounds: int, tasks_per_round: int,
+    ml_url: str, policies: list[str], use_llm: bool, seed: int,
+) -> dict:
+    rng = random.Random(seed)
+    run_id = str(uuid.uuid4())[:8]
+    started_at = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
+
+    user_personas = [
+        (f"sim-{run_id}-u{i}", PERSONAS[i % len(PERSONAS)])
+        for i in range(n_users)
+    ]
+
+    acc: dict[str, dict] = {
+        p: {
+            "total_reward": 0.0, "n_pulls": 0,
+            "cumulative_rewards": [],
+            "action_counts": {a: 0 for a in ACTIONS},
+        }
+        for p in policies
+    }
+    events: list[dict] = []
+
+    with httpx.Client(trust_env=False) as client:
+        for rnd in range(n_rounds):
+            hour = rng.randint(6, 22)
+            dow = rng.randint(0, 6)
+            round_rewards = {p: 0.0 for p in policies}
+
+            for user_id, persona in user_personas:
+                seed_tasks = rnd * 997 + abs(hash(user_id)) % 997
+                tasks = generate_task_pool(n=tasks_per_round, seed=seed_tasks)
+
+                for policy in policies:
+                    p_user = f"{user_id}-{policy}"
+                    scored = _call_score(client, ml_url, policy, p_user, tasks, hour, dow)
+                    if not scored:
+                        continue
+                    tip_id = scored.get("tip_id")
+                    tip = next((t for t in tasks if t["id"] == tip_id), None)
+                    if not tip:
+                        continue
+
+                    action, dwell_ms, reward = judge(persona, tip, hour, dow, rng, use_llm=use_llm)
+                    _call_reward(client, ml_url, policy, p_user, tip_id, reward, {
+                        "hour_of_day": hour,
+                        "is_overdue": tip["features"]["is_overdue"],
+                        "task_age_days": tip["features"]["task_age_days"],
+                        "priority": tip["features"]["priority"],
+                    }, day_of_week=dow)
+
+                    acc[policy]["total_reward"] += reward
+                    acc[policy]["n_pulls"] += 1
+                    acc[policy]["action_counts"][action] += 1
+                    round_rewards[policy] += reward
+                    events.append({
+                        "round": rnd, "user_id": user_id, "persona": persona.name,
+                        "policy": policy, "tip_content": tip["content"],
+                        "priority": tip["features"]["priority"],
+                        "is_overdue": tip["features"]["is_overdue"],
+                        "action": action, "dwell_ms": dwell_ms, "reward": reward,
+                        "hour": hour, "day_of_week": dow,
+                    })
+
+            for p in policies:
+                prev = acc[p]["cumulative_rewards"][-1] if acc[p]["cumulative_rewards"] else 0.0
+                acc[p]["cumulative_rewards"].append(prev + round_rewards[p])
+
+            mode = "llm" if use_llm else "rule"
+            print(f"  Round {rnd+1:>3}/{n_rounds} [{mode}]  " + "  ".join(
+                f"{p}={acc[p]['cumulative_rewards'][-1]:+.2f}" for p in policies
+            ))
+
+    return _build_result(run_id, started_at, policies, acc, events,
+                         n_users, n_rounds, tasks_per_round, use_llm, seed)
+
+
+# ── Claude Code judge — phase 1: score ─────────────────────────────────────
+
+def run_score_phase(
+    n_users: int, n_rounds: int, tasks_per_round: int,
+    ml_url: str, policies: list[str], seed: int, out_path: str,
+) -> None:
+    """Score all candidates and write judgment requests for Claude Code."""
+    rng = random.Random(seed)
+    run_id = str(uuid.uuid4())[:8]
+    started_at = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
+
+    user_personas = [
+        (f"sim-{run_id}-u{i}", PERSONAS[i % len(PERSONAS)])
+        for i in range(n_users)
+    ]
+
+    plan_rounds: list[dict] = []
+    judgment_requests: list[dict] = []
+
+    print(f"[Phase 1] Scoring {n_rounds} rounds × {n_users} users × {len(policies)} policies…")
+
+    with httpx.Client(trust_env=False) as client:
+        for rnd in range(n_rounds):
+            hour = rng.randint(6, 22)
+            dow = rng.randint(0, 6)
+            round_sessions: list[dict] = []
+
+            for user_id, persona in user_personas:
+                seed_tasks = rnd * 997 + abs(hash(user_id)) % 997
+                tasks = generate_task_pool(n=tasks_per_round, seed=seed_tasks)
+
+                for policy in policies:
+                    p_user = f"{user_id}-{policy}"
+                    scored = _call_score(client, ml_url, policy, p_user, tasks, hour, dow)
+                    if not scored:
+                        continue
+                    tip_id = scored.get("tip_id")
+                    tip = next((t for t in tasks if t["id"] == tip_id), None)
+                    if not tip:
+                        continue
+
+                    req_id = f"r{rnd}_{user_id.split('-')[-1]}_{policy}"
+                    round_sessions.append({
+                        "req_id": req_id,
+                        "p_user": p_user,
+                        "policy": policy,
+                        "user_id": user_id,
+                        "persona_name": persona.name,
+                        "tip_id": tip_id,
+                        "tip_features": tip["features"],
+                        "tip_content": tip["content"],
+                        "ml_score": scored.get("score"),
+                    })
+
+                    judgment_requests.append({
+                        "id": req_id,
+                        "round": rnd,
+                        "hour": hour,
+                        "day_of_week": dow,
+                        "policy": policy,
+                        "persona_name": persona.name,
+                        "persona_description": persona.description,
+                        "tip_content": tip["content"],
+                        "priority": tip["features"]["priority"],
+                        "is_overdue": tip["features"]["is_overdue"],
+                        "age_days": tip["features"]["task_age_days"],
+                        "ml_score": scored.get("score"),
+                    })
+
+            plan_rounds.append({
+                "round": rnd, "hour": hour, "dow": dow,
+                "sessions": round_sessions,
+            })
+            print(f"  Round {rnd+1:>3}/{n_rounds}: {len(round_sessions)} sessions scored")
+
+    plan = {
+        "run_id": run_id,
+        "started_at": started_at,
+        "config": {
+            "n_users": n_users, "n_rounds": n_rounds,
+            "tasks_per_round": tasks_per_round, "policies": policies,
+            "use_llm": False, "seed": seed,
+        },
+        "user_personas": [
+            {"user_id": uid, "persona_name": p.name, "persona_description": p.description}
+            for uid, p in user_personas
+        ],
+        "rounds": plan_rounds,
+    }
+
+    base = out_path.replace(".json", "")
+    plan_path = f"{base}-plan.json"
+    requests_path = f"{base}-requests.json"
+    responses_path = f"{base}-responses.json"
+
+    Path(plan_path).write_text(json.dumps(plan, indent=2))
+    Path(requests_path).write_text(json.dumps(judgment_requests, indent=2))
+
+    print()
+    print("=" * 60)
+    print(f"Phase 1 complete — {len(judgment_requests)} judgment requests.")
+    print()
+    print(f"  Requests : {requests_path}")
+    print(f"  Plan     : {plan_path}")
+    print()
+    print('Claude Code: read the requests file, judge each tip for the persona,')
+    print(f'then write your responses to: {responses_path}')
+    print()
+    print('Response format: { "<id>": "<action>" | { "action": "<action>", "dwell_ms": <int> } }')
+    print('Valid actions: done | snooze | dismiss')
+    print()
+    print('For "done", optionally specify dwell_ms (ms between tip appearing and user acting):')
+    print('  { "r0_u0_linucb-v1": { "action": "done", "dwell_ms": 45000 } }  # magic zone')
+    print('  { "r0_u0_linucb-v1": "snooze" }  # plain string also ok (uses default 60s dwell for done)')
+    print()
+    print('Reward is inferred from action + dwell_ms:')
+    print('  dismiss          → -1.0')
+    print('  snooze           →  0.1')
+    print('  done < 15s       → -0.3  (stale task)')
+    print('  done 15s–2min    →  1.0  (magic!)')
+    print('  done 2–10min     →  0.6  (good)')
+    print('  done > 10min     →  0.3  (eventually)')
+    print()
+    print('Then run Phase 2:')
+    print(f'  python runner.py --judge claude-code --phase reward \\')
+    print(f'    --plan {plan_path} --out {out_path}')
+
+
+# ── Claude Code judge — phase 2: reward ────────────────────────────────────
+
+def run_reward_phase(plan_path: str, out_path: str, ml_url: str) -> dict:
+    """Apply Claude Code judgments, send reward signals, compute metrics."""
+    plan = json.loads(Path(plan_path).read_text())
+    base = plan_path.replace("-plan.json", "")
+    responses_path = f"{base}-responses.json"
+
+    if not Path(responses_path).exists():
+        print(f"ERROR: responses file not found: {responses_path}", file=sys.stderr)
+        sys.exit(1)
+
+    raw_responses = json.loads(Path(responses_path).read_text())
+
+    # Responses can be either { id: "action" } or { id: { action, dwell_ms } }
+    def _parse_response(v) -> tuple[str, int]:
+        if isinstance(v, dict):
+            return v["action"], int(v.get("dwell_ms", 60_000))
+        return str(v), 60_000  # plain string → assume 60s dwell for "done"
+
+    responses: dict[str, tuple[str, int]] = {k: _parse_response(v) for k, v in raw_responses.items()}
+
+    invalid = {k: v[0] for k, v in responses.items() if v[0] not in ACTIONS}
+    if invalid:
+        print(f"ERROR: invalid actions in responses: {invalid}", file=sys.stderr)
+        sys.exit(1)
+
+    policies: list[str] = plan["config"]["policies"]
+    acc: dict[str, dict] = {
+        p: {
+            "total_reward": 0.0, "n_pulls": 0,
+            "cumulative_rewards": [],
+            "action_counts": {a: 0 for a in ACTIONS},
+        }
+        for p in policies
+    }
+    events: list[dict] = []
+    persona_map = {u["user_id"]: u["persona_name"] for u in plan["user_personas"]}
+    missing_responses = 0
+
+    print(f"[Phase 2] Applying {len(responses)} judgments → reward calls…")
+
+    with httpx.Client(trust_env=False) as client:
+        for rnd_data in plan["rounds"]:
+            rnd = rnd_data["round"]
+            round_rewards = {p: 0.0 for p in policies}
+
+            for session in rnd_data["sessions"]:
+                req_id = session["req_id"]
+                resp = responses.get(req_id)
+                if not resp:
+                    print(f"  [warn] no response for {req_id}, defaulting to snooze")
+                    action, dwell_ms = "snooze", 10_000
+                    missing_responses += 1
+                else:
+                    action, dwell_ms = resp
+
+                reward = infer_reward(action, dwell_ms)
+                _call_reward(
+                    client, ml_url, session["policy"], session["p_user"],
+                    session["tip_id"], reward,
+                    {"hour_of_day": rnd_data["hour"], **session["tip_features"]},
+                    day_of_week=rnd_data["dow"],
+                )
+
+                p = session["policy"]
+                acc[p]["total_reward"] += reward
+                acc[p]["n_pulls"] += 1
+                acc[p]["action_counts"][action] += 1
+                round_rewards[p] += reward
+
+                events.append({
+                    "round": rnd,
+                    "user_id": session["user_id"],
+                    "persona": persona_map.get(session["user_id"], "?"),
+                    "policy": p,
+                    "tip_content": session["tip_content"],
+                    "priority": session["tip_features"]["priority"],
+                    "is_overdue": session["tip_features"]["is_overdue"],
+                    "action": action,
+                    "dwell_ms": dwell_ms,
+                    "reward": reward,
+                    "hour": rnd_data["hour"],
+                    "day_of_week": rnd_data["dow"],
+                })
+
+            for p in policies:
+                prev = acc[p]["cumulative_rewards"][-1] if acc[p]["cumulative_rewards"] else 0.0
+                acc[p]["cumulative_rewards"].append(prev + round_rewards[p])
+
+            print(f"  Round {rnd+1:>3}/{plan['config']['n_rounds']} [cc]  " + "  ".join(
+                f"{p}={acc[p]['cumulative_rewards'][-1]:+.2f}" for p in policies
+            ))
+
+    if missing_responses:
+        print(f"  [warn] {missing_responses} requests had no response (defaulted to snooze)")
+
+    cfg = plan["config"]
+    result = _build_result(
+        plan["run_id"], plan["started_at"], policies, acc, events,
+        cfg["n_users"], cfg["n_rounds"], cfg["tasks_per_round"],
+        use_llm=False, seed=cfg["seed"],
+    )
+    result["judge_mode"] = "claude-code"
+    Path(out_path).write_text(json.dumps(result, indent=2))
+    return result
+
+
+# ── Shared result builder ───────────────────────────────────────────────────
+
+def _build_result(
+    run_id: str, started_at: str, policies: list[str],
+    acc: dict, events: list[dict],
+    n_users: int, n_rounds: int, tasks_per_round: int,
+    use_llm: bool, seed: int,
+) -> dict:
+    summary = {
+        p: {
+            "total_reward": acc[p]["total_reward"],
+            "mean_reward": (
+                acc[p]["total_reward"] / acc[p]["n_pulls"]
+                if acc[p]["n_pulls"] > 0 else 0.0
+            ),
+            "n_pulls": acc[p]["n_pulls"],
+            "cumulative_rewards": acc[p]["cumulative_rewards"],
+            "action_counts": acc[p]["action_counts"],
+        }
+        for p in policies
+    }
+    winner = max(policies, key=lambda p: summary[p]["total_reward"])
+
+    persona_breakdown: dict[str, dict] = {}
+    for ev in events:
+        pname = ev["persona"]
+        pol = ev["policy"]
+        persona_breakdown.setdefault(pname, {}).setdefault(pol, {"reward": 0.0, "n": 0})
+        persona_breakdown[pname][pol]["reward"] += ev["reward"]
+        persona_breakdown[pname][pol]["n"] += 1
+
+    return {
+        "run_id": run_id,
+        "started_at": started_at,
+        "finished_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+        "config": {
+            "n_users": n_users, "n_rounds": n_rounds,
+            "tasks_per_round": tasks_per_round, "policies": policies,
+            "use_llm": use_llm, "seed": seed,
+        },
+        "summary": summary,
+        "winner": winner,
+        "persona_breakdown": persona_breakdown,
+        "events": events,
+    }
+
+
+# ── CLI ─────────────────────────────────────────────────────────────────────
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="oO simulation runner")
+    parser.add_argument("--judge", choices=["rule", "llm", "claude-code"], default="rule")
+    parser.add_argument("--phase", choices=["score", "reward"], default=None,
+                        help="For --judge claude-code only")
+    parser.add_argument("--plan", default=None,
+                        help="Plan file path (for --judge claude-code --phase reward)")
+    parser.add_argument("--n-users", type=int, default=5)
+    parser.add_argument("--n-rounds", type=int, default=20)
+    parser.add_argument("--tasks-per-round", type=int, default=8)
+    parser.add_argument("--ml-url", default="http://localhost:5001")
+    parser.add_argument("--policies", nargs="+", default=["linucb-v1", "egreedy-v1"])
+    parser.add_argument("--no-llm", action="store_true",
+                        help="Alias for --judge rule (backwards compat)")
+    parser.add_argument("--seed", type=int, default=42)
+    parser.add_argument("--out", default=None)
+    args = parser.parse_args()
+
+    if args.no_llm:
+        args.judge = "rule"
+
+    out_path = args.out or f"/tmp/oo-sim-{int(time.time())}.json"
+
+    if args.judge == "claude-code":
+        if args.phase == "score":
+            run_score_phase(
+                n_users=args.n_users, n_rounds=args.n_rounds,
+                tasks_per_round=args.tasks_per_round, ml_url=args.ml_url,
+                policies=args.policies, seed=args.seed, out_path=out_path,
+            )
+        elif args.phase == "reward":
+            if not args.plan:
+                print("ERROR: --plan is required for --phase reward", file=sys.stderr)
+                sys.exit(1)
+            result = run_reward_phase(args.plan, out_path, args.ml_url)
+            print()
+            print(f"Winner : {result['winner']}")
+            for p, s in result["summary"].items():
+                print(f"  {p:20s}  total={s['total_reward']:+.2f}  mean={s['mean_reward']:+.4f}  pulls={s['n_pulls']}")
+            print(f"Results: {out_path}")
+        else:
+            print("ERROR: --judge claude-code requires --phase score or --phase reward",
+                  file=sys.stderr)
+            sys.exit(1)
+    else:
+        use_llm = (args.judge == "llm")
+        print(f"oO simulation: {args.n_users} users × {args.n_rounds} rounds")
+        print(f"Policies : {args.policies}")
+        print(f"ML URL   : {args.ml_url}")
+        print(f"Judge    : {args.judge}")
+        print()
+
+        result = run_simulation(
+            n_users=args.n_users, n_rounds=args.n_rounds,
+            tasks_per_round=args.tasks_per_round, ml_url=args.ml_url,
+            policies=args.policies, use_llm=use_llm, seed=args.seed,
+        )
+        Path(out_path).write_text(json.dumps(result, indent=2))
+        print()
+        print(f"Winner : {result['winner']}")
+        for p, s in result["summary"].items():
+            print(f"  {p:20s}  total={s['total_reward']:+.2f}  mean={s['mean_reward']:+.4f}  pulls={s['n_pulls']}")
+        print(f"Results: {out_path}")

ml/experiments/sim/task_generator.py

@@ -0,0 +1,62 @@
+"""Generate synthetic task pools for simulation."""
+
+from __future__ import annotations
+
+import random
+
+_TEMPLATES = [
+    "Send weekly report to team",
+    "Review pull request #{n}",
+    "Schedule meeting with {name}",
+    "Update project documentation",
+    "Fix bug in authentication module",
+    "Prepare presentation for stakeholders",
+    "Call back {name}",
+    "Submit expense report",
+    "Review quarterly goals",
+    "Clean up inbox",
+    "Follow up on proposal to {name}",
+    "Complete onboarding checklist",
+    "Write tests for feature #{n}",
+    "Deploy hotfix to production",
+    "Respond to support ticket #{n}",
+    "Draft release notes",
+    "Update dependencies",
+    "Review design mockups",
+    "Archive old tickets",
+    "Check in with {name}",
+]
+
+_NAMES = ["Alice", "Bob", "Carol", "David", "Eve", "Frank", "Grace"]
+
+
+def generate_task_pool(n: int = 10, seed: int | None = None) -> list[dict]:
+    """Return n synthetic tasks with randomly sampled features."""
+    rng = random.Random(seed)
+
+    tasks = []
+    for i in range(n):
+        priority = rng.choices([1, 2, 3, 4], weights=[0.3, 0.3, 0.25, 0.15])[0]
+        # age_days: most tasks fresh, a few stale
+        age_days = rng.choices(
+            [0.0, 0.5, 1.0, 3.0, 7.0, 14.0],
+            weights=[0.35, 0.20, 0.20, 0.12, 0.08, 0.05],
+        )[0] + rng.random() * 0.5
+        # is_overdue only meaningful when age > 0
+        is_overdue = age_days > 0.5 and rng.random() < 0.65
+
+        template = rng.choice(_TEMPLATES)
+        content = template.format(n=rng.randint(100, 999), name=rng.choice(_NAMES))
+
+        tasks.append({
+            "id": f"sim:{i}",
+            "content": content,
+            "source": "sim",
+            "features": {
+                "is_overdue": is_overdue,
+                "task_age_days": age_days if is_overdue else 0.0,
+                "priority": priority,
+            },
+        })
+
+    return tasks