app.py

"""
FastAPI server exposing the Content Moderation Queue OpenEnv environment.

Each call to /reset creates an isolated session with its own state.
Pass the returned session_id to /step and /state to avoid interference
between concurrent users or test runs.
"""

import uuid
from typing import Optional, Dict
from fastapi import FastAPI, HTTPException, Query
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import HTMLResponse

from environment import ContentModerationEnv
from environment.models import Action, Observation, StepResult, EnvironmentState

# ═══════════════════════════════════════════════════════════════════════════
# Swagger CSS — warm cozy theme
# ═══════════════════════════════════════════════════════════════════════════

SWAGGER_CSS = """
body { background: #fdf0dc !important; }

.swagger-ui .topbar {
  background: linear-gradient(135deg, #f4a833, #e8923a) !important;
  border-bottom: 2px solid #e8923a !important;
  padding: 10px 0 !important;
}
.swagger-ui .topbar a { color: #fff !important; }
.swagger-ui .topbar .download-url-wrapper .select-label select {
  border-color: rgba(255,255,255,0.3) !important;
  color: #fff !important;
}

.swagger-ui { color: #5a4530 !important; font-family: 'Inter', system-ui, sans-serif !important; }
.swagger-ui .info .title { color: #3d2b1a !important; font-weight: 700 !important; }
.swagger-ui .info .description p { color: #7a6550 !important; }
.swagger-ui .info .title small.version-stamp {
  background: #f4a833 !important;
  color: #fff !important;
  border: none !important;
  border-radius: 12px !important;
}

.swagger-ui .scheme-container {
  background: #fbe8c8 !important;
  border: 1px solid #f0d4a0 !important;
  border-radius: 14px !important;
  box-shadow: 0 2px 8px rgba(180,140,80,0.08) !important;
}

/* Operation blocks */
.swagger-ui .opblock {
  border-radius: 14px !important;
  box-shadow: 0 2px 10px rgba(180,140,80,0.08) !important;
  margin-bottom: 14px !important;
  overflow: hidden !important;
}
.swagger-ui .opblock .opblock-summary { border: none !important; }
.swagger-ui .opblock .opblock-summary-method { border-radius: 8px !important; font-weight: 700 !important; }
.swagger-ui .opblock .opblock-summary-description { color: #7a6550 !important; }
.swagger-ui .opblock .opblock-summary-path { color: #3d2b1a !important; }

/* GET blocks — warm teal */
.swagger-ui .opblock-get {
  background: #fef9f0 !important;
  border: 1.5px solid #b8d8c8 !important;
}
.swagger-ui .opblock-get .opblock-summary-method {
  background: #5baa8a !important;
  color: #fff !important;
}
.swagger-ui .opblock-get .opblock-summary { border-color: transparent !important; }

/* POST blocks — warm orange */
.swagger-ui .opblock-post {
  background: #fef6ed !important;
  border: 1.5px solid #f0c880 !important;
}
.swagger-ui .opblock-post .opblock-summary-method {
  background: #f4a833 !important;
  color: #fff !important;
}
.swagger-ui .opblock-post .opblock-summary { border-color: transparent !important; }

/* Body */
.swagger-ui .opblock-body { background: #fdf5e8 !important; }
.swagger-ui .opblock-body pre {
  background: #fef9f0 !important;
  color: #5a4530 !important;
  border: 1px solid #f0d4a0 !important;
  border-radius: 10px !important;
}
.swagger-ui .opblock-description-wrapper p { color: #7a6550 !important; }

/* Tables */
.swagger-ui table thead tr td, .swagger-ui table thead tr th {
  color: #7a6550 !important;
  border-color: #f0d4a0 !important;
}
.swagger-ui table tbody tr td {
  color: #5a4530 !important;
  border-color: #f5e0c0 !important;
}

/* Parameters */
.swagger-ui .parameter__name { color: #3d2b1a !important; }
.swagger-ui .parameter__type { color: #5baa8a !important; }
.swagger-ui .parameter__name.required::after { color: #e86040 !important; }
.swagger-ui .parameters-col_description p { color: #7a6550 !important; }

/* Inputs */
.swagger-ui input[type=text], .swagger-ui textarea, .swagger-ui select {
  background: #fef9f0 !important;
  color: #3d2b1a !important;
  border: 1.5px solid #f0d4a0 !important;
  border-radius: 10px !important;
  font-family: 'JetBrains Mono', monospace !important;
}
.swagger-ui input[type=text]:focus, .swagger-ui textarea:focus {
  border-color: #f4a833 !important;
  box-shadow: 0 0 0 3px rgba(244,168,51,0.15) !important;
}

/* Execute button */
.swagger-ui .btn.execute {
  background: linear-gradient(135deg, #f4a833, #e8923a) !important;
  color: #fff !important;
  border: none !important;
  border-radius: 10px !important;
  box-shadow: 0 3px 12px rgba(244,168,51,0.3) !important;
  font-weight: 600 !important;
  padding: 8px 24px !important;
}
.swagger-ui .btn.execute:hover {
  box-shadow: 0 5px 20px rgba(244,168,51,0.4) !important;
  transform: translateY(-1px);
}

/* Try-out button */
.swagger-ui .try-out__btn {
  color: #f4a833 !important;
  border-color: #f0c880 !important;
  border-radius: 10px !important;
}
.swagger-ui .try-out__btn:hover { background: rgba(244,168,51,0.08) !important; }

/* Cancel */
.swagger-ui .btn-group .cancel { color: #7a6550 !important; border-color: #e0c8a0 !important; }

/* Responses */
.swagger-ui .responses-inner { background: transparent !important; }
.swagger-ui .response-col_status { color: #5baa8a !important; font-weight: 600 !important; }
.swagger-ui .response-col_description { color: #7a6550 !important; }

/* Live response */
.swagger-ui .microlight {
  background: #fef9f0 !important;
  color: #5a4530 !important;
  border-radius: 10px !important;
  border: 1px solid #f0d4a0 !important;
}

/* Models */
.swagger-ui section.models {
  border: 1.5px solid #f0d4a0 !important;
  border-radius: 14px !important;
  background: #fef6ed !important;
}
.swagger-ui section.models h4 { color: #3d2b1a !important; border-color: #f0d4a0 !important; }
.swagger-ui .model-title { color: #3d2b1a !important; }
.swagger-ui .model { color: #5a4530 !important; }
.swagger-ui .model .property { color: #7a6550 !important; }
.swagger-ui .model .property.primitive { color: #5baa8a !important; }
.swagger-ui .prop-type { color: #c47830 !important; }
.swagger-ui .model-box { background: #fdf5e8 !important; border-radius: 10px !important; }
.swagger-ui section.models .model-container {
  background: #fdf5e8 !important;
  border-radius: 10px !important;
  margin: 4px 0 !important;
}

/* Links */
.swagger-ui a { color: #e08030 !important; }
.swagger-ui a:hover { color: #c06020 !important; }

/* Section tags */
.swagger-ui .opblock-tag { color: #3d2b1a !important; border-color: #f0d4a0 !important; }

/* Expand arrows */
.swagger-ui .expand-operation svg, .swagger-ui .expand-methods svg { fill: #c4a070 !important; }

/* Markdown */
.swagger-ui .markdown p, .swagger-ui .renderedMarkdown p { color: #7a6550 !important; }
.swagger-ui .markdown li, .swagger-ui .renderedMarkdown li { color: #7a6550 !important; }
.swagger-ui .markdown code {
  background: #fbe8c8 !important;
  color: #c47830 !important;
  border-radius: 6px !important;
  padding: 1px 6px !important;
}

/* Scrollbar */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: #fdf0dc; }
::-webkit-scrollbar-thumb { background: #e0c8a0; border-radius: 3px; }
"""

# ═══════════════════════════════════════════════════════════════════════════
# App setup
# ═══════════════════════════════════════════════════════════════════════════

app = FastAPI(
    title="Content Moderation Queue — OpenEnv",
    description=(
        "A real-world content moderation environment where AI agents learn "
        "to triage social media posts using a tiered policy framework. "
        "Implements the full OpenEnv spec: step() / reset() / state(). "
        "Each /reset call creates an isolated session — pass session_id to /step and /state."
    ),
    version="1.0.0",
    docs_url=None,
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

_sessions: Dict[str, ContentModerationEnv] = {}
MAX_SESSIONS = 200
_shared_env = ContentModerationEnv()


def _get_session(session_id: str) -> ContentModerationEnv:
    if session_id not in _sessions:
        raise HTTPException(
            status_code=404,
            detail=f"Session '{session_id}' not found. Call POST /reset first to create a session."
        )
    return _sessions[session_id]


def _new_session() -> tuple[str, ContentModerationEnv]:
    sid = str(uuid.uuid4())[:8]
    if len(_sessions) >= MAX_SESSIONS:
        oldest = next(iter(_sessions))
        del _sessions[oldest]
    env = ContentModerationEnv()
    _sessions[sid] = env
    return sid, env


# ═══════════════════════════════════════════════════════════════════════════
# Landing page — warm cozy theme
# ═══════════════════════════════════════════════════════════════════════════

LANDING_HTML = """
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Content Moderation Queue — OpenEnv</title>
  <link href="https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap" rel="stylesheet">
  <style>
    :root {
      --cream: #fdf0dc;
      --cream2: #fbe8c8;
      --card: #fef6ed;
      --card2: #fef9f0;
      --border: #f0d4a0;
      --border2: #e8c890;
      --text: #3d2b1a;
      --text2: #5a4530;
      --muted: #9a8060;
      --orange: #f4a833;
      --orange2: #e8923a;
      --peach: #f8c06a;
      --teal: #5baa8a;
      --red-soft: #e86040;
      --rose: #e88070;
      --sand: #d4b888;
    }

    * { margin: 0; padding: 0; box-sizing: border-box; }

    body {
      font-family: 'Inter', system-ui, sans-serif;
      background: var(--cream);
      color: var(--text2);
      min-height: 100vh;
      background-image:
        radial-gradient(ellipse at 30% 0%, rgba(244,168,51,0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 100%, rgba(232,146,58,0.06) 0%, transparent 50%);
    }

    /* ═══ HERO ═══ */
    .hero {
      background: linear-gradient(160deg, #fbe8c8 0%, #f8d8a4 40%, #f4c87a 100%);
      padding: 52px 24px 44px;
      text-align: center;
      position: relative;
      overflow: hidden;
      border-bottom: 2px solid var(--border);
    }
    .hero::before {
      content: '';
      position: absolute;
      bottom: -2px; left: 0; right: 0;
      height: 40px;
      background: url("data:image/svg+xml,%3Csvg viewBox='0 0 1200 40' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0,20 Q150,0 300,20 Q450,40 600,20 Q750,0 900,20 Q1050,40 1200,20 V40 H0 Z' fill='%23fdf0dc'/%3E%3C/svg%3E") no-repeat center;
      background-size: cover;
    }

    .hero-icon {
      width: 72px; height: 72px;
      background: rgba(255,255,255,0.6);
      border: 2px solid rgba(255,255,255,0.8);
      border-radius: 20px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-size: 2.2rem;
      margin-bottom: 16px;
      box-shadow: 0 4px 16px rgba(200,150,60,0.15);
    }

    .hero h1 {
      font-size: 2rem;
      font-weight: 800;
      color: var(--text);
      letter-spacing: -0.5px;
      margin-bottom: 10px;
    }

    .badges { display: flex; gap: 8px; justify-content: center; margin-bottom: 16px; }
    .badge {
      padding: 4px 14px;
      border-radius: 20px;
      font-size: 0.68rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.8px;
    }
    .b-env { background: var(--orange); color: #fff; }
    .b-live { background: var(--teal); color: #fff; }
    .b-ver { background: rgba(255,255,255,0.6); color: var(--muted); border: 1px solid var(--border); }

    .hero-desc {
      max-width: 520px;
      margin: 0 auto;
      color: var(--text2);
      font-size: 0.92rem;
      line-height: 1.65;
      opacity: 0.85;
    }

    .container { max-width: 900px; margin: 0 auto; padding: 32px 24px; }

    /* ═══ CARD BASE ═══ */
    .card {
      background: var(--card);
      border: 1.5px solid var(--border);
      border-radius: 16px;
      box-shadow: 0 2px 10px rgba(180,140,80,0.06);
    }

    /* ═══ STATS ═══ */
    .stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin-bottom: 32px; }
    .stat { padding: 20px 14px; text-align: center; }
    .stat-val {
      font-size: 1.8rem;
      font-weight: 800;
      color: var(--orange2);
    }
    .stat-lbl {
      font-size: 0.7rem;
      color: var(--muted);
      text-transform: uppercase;
      letter-spacing: 0.8px;
      margin-top: 4px;
      font-weight: 500;
    }

    /* ═══ SECTION TITLE ═══ */
    .stitle {
      font-size: 0.72rem;
      font-weight: 700;
      color: var(--muted);
      text-transform: uppercase;
      letter-spacing: 1.5px;
      margin-bottom: 14px;
      display: flex;
      align-items: center;
      gap: 12px;
    }
    .stitle::after {
      content: '';
      flex: 1;
      height: 1.5px;
      background: linear-gradient(90deg, var(--border), transparent);
    }

    /* ═══ HOW IT WORKS ═══ */
    .flow { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-bottom: 32px; }
    .flow-card {
      padding: 20px 14px;
      text-align: center;
      position: relative;
      overflow: hidden;
    }
    .flow-card::before {
      content: '';
      position: absolute;
      top: 0; left: 0; right: 0;
      height: 3px;
      background: linear-gradient(90deg, var(--orange), var(--peach));
      border-radius: 16px 16px 0 0;
    }
    .flow-n {
      display: inline-flex;
      width: 32px; height: 32px;
      align-items: center;
      justify-content: center;
      background: var(--orange);
      color: #fff;
      border-radius: 10px;
      font-size: 0.85rem;
      font-weight: 700;
    }
    .flow-t { font-size: 0.88rem; font-weight: 600; color: var(--text); margin-top: 8px; }
    .flow-d { font-size: 0.75rem; color: var(--muted); margin-top: 4px; }
    .flow-c {
      display: inline-block;
      margin-top: 8px;
      font-family: 'JetBrains Mono', monospace;
      font-size: 0.67rem;
      color: var(--teal);
      background: var(--cream2);
      padding: 3px 10px;
      border-radius: 8px;
      border: 1px solid var(--border);
      font-weight: 500;
    }

    /* ═══ TASKS ═══ */
    .tasks { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-bottom: 32px; }
    .task { padding: 22px 18px; position: relative; overflow: hidden; }
    .task::before {
      content: '';
      position: absolute;
      left: 0; top: 0; bottom: 0;
      width: 4px;
      border-radius: 16px 0 0 16px;
    }
    .t-easy::before { background: var(--teal); }
    .t-med::before { background: var(--orange); }
    .t-hard::before { background: var(--red-soft); }
    .task-diff {
      font-size: 0.62rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 1.2px;
      margin-bottom: 6px;
    }
    .t-easy .task-diff { color: var(--teal); }
    .t-med .task-diff { color: var(--orange2); }
    .t-hard .task-diff { color: var(--red-soft); }
    .task-name { font-size: 0.92rem; font-weight: 700; color: var(--text); margin-bottom: 6px; }
    .task-desc { font-size: 0.78rem; color: var(--muted); line-height: 1.5; margin-bottom: 12px; }
    .chips { display: flex; gap: 6px; flex-wrap: wrap; }
    .chip {
      font-size: 0.65rem;
      font-weight: 500;
      padding: 3px 10px;
      border-radius: 8px;
      background: var(--cream2);
      border: 1px solid var(--border);
      color: var(--muted);
    }

    /* ═══ ACTIONS ═══ */
    .actions { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-bottom: 32px; }
    .act { padding: 14px 16px; transition: transform 0.2s; }
    .act:hover { transform: translateY(-2px); }
    .act-name {
      font-family: 'JetBrains Mono', monospace;
      font-size: 0.82rem;
      font-weight: 600;
      margin-bottom: 3px;
    }
    .act-desc { font-size: 0.72rem; color: var(--muted); }
    .a-approve .act-name { color: var(--teal); }
    .a-warn .act-name { color: var(--orange); }
    .a-remove .act-name { color: var(--orange2); }
    .a-bant .act-name { color: var(--red-soft); }
    .a-banp .act-name { color: #c43030; }
    .a-esc .act-name { color: #9070b0; }

    /* ═══ ENDPOINTS ═══ */
    .ep-table { margin-bottom: 32px; overflow: hidden; }
    .ep {
      display: flex;
      align-items: center;
      padding: 12px 18px;
      gap: 14px;
      border-bottom: 1px solid rgba(240,212,160,0.5);
    }
    .ep:last-child { border-bottom: none; }
    .ep-m {
      font-size: 0.64rem;
      font-weight: 700;
      padding: 4px 10px;
      border-radius: 8px;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      min-width: 48px;
      text-align: center;
    }
    .ep-g { background: rgba(91,170,138,0.12); color: var(--teal); border: 1px solid rgba(91,170,138,0.25); }
    .ep-p { background: rgba(244,168,51,0.12); color: var(--orange2); border: 1px solid rgba(244,168,51,0.25); }
    .ep-path {
      font-family: 'JetBrains Mono', monospace;
      font-size: 0.8rem;
      color: var(--text);
      flex: 1;
      font-weight: 500;
    }
    .ep-info { font-size: 0.78rem; color: var(--muted); }

    /* ═══ REWARD ═══ */
    .reward { padding: 22px 20px; margin-bottom: 32px; }
    .reward h3 { font-size: 0.95rem; font-weight: 700; color: var(--text); margin-bottom: 14px; }
    .r-item { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; font-size: 0.82rem; color: var(--text2); }
    .r-dot { width: 10px; height: 10px; border-radius: 50%; flex-shrink: 0; }
    .rg { background: var(--teal); }
    .ry { background: var(--orange); }
    .rb { background: #5a9ac0; }
    .rr { background: var(--rose); }

    /* ═══ BASELINE ═══ */
    .baseline { padding: 22px 20px; margin-bottom: 32px; }
    .baseline h3 { font-size: 0.92rem; font-weight: 700; color: var(--text); margin-bottom: 6px; }
    .bl-sub { font-size: 0.73rem; color: var(--muted); margin-bottom: 16px; }
    .sc-row { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; }
    .sc-lbl { font-size: 0.78rem; width: 72px; font-weight: 600; }
    .sc-bg {
      flex: 1; height: 24px; border-radius: 12px;
      background: var(--cream2);
      border: 1px solid var(--border);
      overflow: hidden;
    }
    .sc-bar { height: 100%; border-radius: 11px; }
    .sc-bar-g { background: linear-gradient(90deg, #4a9a7a, var(--teal)); }
    .sc-bar-y { background: linear-gradient(90deg, #d4922a, var(--orange)); }
    .sc-bar-r { background: linear-gradient(90deg, #c84830, var(--red-soft)); }
    .sc-val { font-size: 0.82rem; font-weight: 700; width: 48px; text-align: right; color: var(--text); }

    /* ═══ CTA ═══ */
    .ctas { display: flex; gap: 12px; margin-bottom: 36px; }
    .cta {
      flex: 1;
      display: block;
      text-align: center;
      padding: 14px 20px;
      border-radius: 12px;
      text-decoration: none;
      font-weight: 600;
      font-size: 0.88rem;
      transition: all 0.25s ease;
    }
    .cta:hover { transform: translateY(-2px); }
    .cta-1 {
      background: linear-gradient(135deg, var(--orange), var(--orange2));
      color: #fff;
      box-shadow: 0 4px 16px rgba(244,168,51,0.25);
    }
    .cta-1:hover { box-shadow: 0 6px 24px rgba(244,168,51,0.35); }
    .cta-2 {
      background: var(--card);
      color: var(--teal);
      border: 1.5px solid rgba(91,170,138,0.3);
    }
    .cta-2:hover { background: rgba(91,170,138,0.06); }
    .cta-3 {
      background: var(--card);
      color: var(--text2);
      border: 1.5px solid var(--border);
    }

    /* ═══ FOOTER ═══ */
    .footer {
      text-align: center;
      padding: 28px 0;
      border-top: 1.5px solid var(--border);
      color: var(--muted);
      font-size: 0.75rem;
    }
    .footer a { color: var(--orange2); text-decoration: none; }
    .footer a:hover { text-decoration: underline; }

    /* ═══ DECORATIVE BLOBS ═══ */
    .blob {
      position: absolute;
      border-radius: 50%;
      opacity: 0.12;
      pointer-events: none;
    }
    .blob-1 { width: 200px; height: 200px; background: var(--orange); top: -60px; right: -40px; }
    .blob-2 { width: 140px; height: 140px; background: var(--peach); bottom: -30px; left: -30px; }

    @media (max-width: 720px) {
      .stats, .flow { grid-template-columns: repeat(2, 1fr); }
      .tasks, .actions { grid-template-columns: 1fr; }
      .ctas { flex-direction: column; }
    }
  </style>
</head>
<body>

  <div class="hero">
    <div class="blob blob-1"></div>
    <div class="blob blob-2"></div>
    <div class="hero-icon">&#128737;&#65039;</div>
    <h1>Content Moderation Queue</h1>
    <div class="badges">
      <span class="badge b-env">OpenEnv</span>
      <span class="badge b-live">Live</span>
      <span class="badge b-ver">v1.0.0</span>
    </div>
    <p class="hero-desc">A real-world RL environment simulating Trust &amp; Safety moderation.
    AI agents triage social media posts, handle appeals, detect crisis content,
    and apply graduated policy enforcement.</p>
  </div>

  <div class="container">

    <div class="stats">
      <div class="card stat"><div class="stat-val">30</div><div class="stat-lbl">Labeled Posts</div></div>
      <div class="card stat"><div class="stat-val">3</div><div class="stat-lbl">Difficulty Levels</div></div>
      <div class="card stat"><div class="stat-val">6</div><div class="stat-lbl">Action Types</div></div>
      <div class="card stat"><div class="stat-val">9</div><div class="stat-lbl">Violation Types</div></div>
    </div>

    <div class="stitle">How It Works</div>
    <div class="flow">
      <div class="card flow-card"><div class="flow-n">1</div><div class="flow-t">Reset</div><div class="flow-d">Start episode, pick difficulty</div><div class="flow-c">POST /reset</div></div>
      <div class="card flow-card"><div class="flow-n">2</div><div class="flow-t">Observe</div><div class="flow-d">Read post, history, context</div><div class="flow-c">session_id</div></div>
      <div class="card flow-card"><div class="flow-n">3</div><div class="flow-t">Decide</div><div class="flow-d">Choose action + violation</div><div class="flow-c">POST /step</div></div>
      <div class="card flow-card"><div class="flow-n">4</div><div class="flow-t">Score</div><div class="flow-d">Get reward 0.0 - 1.0</div><div class="flow-c">GET /state</div></div>
    </div>

    <div class="stitle">Tasks</div>
    <div class="tasks">
      <div class="card task t-easy">
        <div class="task-diff">Easy</div>
        <div class="task-name">Binary Content Moderation</div>
        <div class="task-desc">Classify 8 posts as safe or harmful. Clear signals: spam, hate speech vs everyday content.</div>
        <div class="chips"><span class="chip">8 posts</span><span class="chip">2 actions</span><span class="chip">Binary</span></div>
      </div>
      <div class="card task t-med">
        <div class="task-diff">Medium</div>
        <div class="task-name">Tiered Policy Enforcement</div>
        <div class="task-desc">Apply 5-level severity. Harsh criticism, repeat offenders, political content, zero-tolerance.</div>
        <div class="chips"><span class="chip">10 posts</span><span class="chip">5 actions</span><span class="chip">Partial credit</span></div>
      </div>
      <div class="card task t-hard">
        <div class="task-diff">Hard</div>
        <div class="task-name">Full Queue + Appeals</div>
        <div class="task-desc">Appeals, gaming slang vs threats, crisis escalation, repeat offenders, second-appeal denials.</div>
        <div class="chips"><span class="chip">12 posts</span><span class="chip">6 actions</span><span class="chip">Context bonus</span></div>
      </div>
    </div>

    <div class="stitle">Action Space</div>
    <div class="actions">
      <div class="card act a-approve"><div class="act-name">approve</div><div class="act-desc">Safe, policy-compliant content</div></div>
      <div class="card act a-warn"><div class="act-name">warn</div><div class="act-desc">Minor first-time violation</div></div>
      <div class="card act a-remove"><div class="act-name">remove</div><div class="act-desc">Clear policy violation</div></div>
      <div class="card act a-bant"><div class="act-name">ban_temporary</div><div class="act-desc">Repeat or serious offense</div></div>
      <div class="card act a-banp"><div class="act-name">ban_permanent</div><div class="act-desc">Zero-tolerance or 5+ violations</div></div>
      <div class="card act a-esc"><div class="act-name">escalate</div><div class="act-desc">Ambiguous, appeals, or crisis</div></div>
    </div>

    <div class="stitle">API Endpoints</div>
    <div class="card ep-table">
      <div class="ep"><span class="ep-m ep-g">GET</span><span class="ep-path">/health</span><span class="ep-info">Liveness check</span></div>
      <div class="ep"><span class="ep-m ep-g">GET</span><span class="ep-path">/tasks</span><span class="ep-info">List all tasks</span></div>
      <div class="ep"><span class="ep-m ep-p">POST</span><span class="ep-path">/reset?task_id=task_easy</span><span class="ep-info">Start episode, get session_id</span></div>
      <div class="ep"><span class="ep-m ep-p">POST</span><span class="ep-path">/step?session_id=abc123</span><span class="ep-info">Submit action, get reward</span></div>
      <div class="ep"><span class="ep-m ep-g">GET</span><span class="ep-path">/state?session_id=abc123</span><span class="ep-info">Full state + score</span></div>
    </div>

    <div class="stitle">Reward Design</div>
    <div class="card reward">
      <div class="r-item"><div class="r-dot rg"></div><div><strong>Non-sparse:</strong> every post scores independently (0.0 - 1.0)</div></div>
      <div class="r-item"><div class="r-dot ry"></div><div><strong>Partial credit:</strong> one severity level off scores ~0.65 instead of 0.0</div></div>
      <div class="r-item"><div class="r-dot rb"></div><div><strong>Context bonus:</strong> +0.3 for history-dependent or context-dependent posts</div></div>
      <div class="r-item"><div class="r-dot rr"></div><div><strong>Violation ID:</strong> correctly identifying the violation category earns bonus</div></div>
    </div>

    <div class="stitle">Baseline Scores</div>
    <div class="card baseline">
      <h3>Meta Llama 3 8B Instruct</h3>
      <div class="bl-sub">temperature=0 | seed=42 | reproducible</div>
      <div class="sc-row"><span class="sc-lbl" style="color:var(--teal)">Easy</span><div class="sc-bg"><div class="sc-bar sc-bar-g" style="width:50%"></div></div><span class="sc-val">0.500</span></div>
      <div class="sc-row"><span class="sc-lbl" style="color:var(--orange2)">Medium</span><div class="sc-bg"><div class="sc-bar sc-bar-y" style="width:53%"></div></div><span class="sc-val">0.533</span></div>
      <div class="sc-row"><span class="sc-lbl" style="color:var(--red-soft)">Hard</span><div class="sc-bg"><div class="sc-bar sc-bar-r" style="width:42%"></div></div><span class="sc-val">0.423</span></div>
    </div>

    <div class="ctas">
      <a class="cta cta-1" href="/docs">Interactive API Docs</a>
      <a class="cta cta-2" href="/tasks">View Tasks</a>
      <a class="cta cta-3" href="/health">Health Check</a>
    </div>

    <div class="footer">
      Content Moderation Queue &mdash; OpenEnv v1.0.0<br>
      Built for the Meta AI Hackathon | <a href="/docs">API Docs</a>
    </div>

  </div>
</body>
</html>
"""

@app.get("/", response_class=HTMLResponse, include_in_schema=False)
def root():
    return LANDING_HTML


@app.get("/docs", include_in_schema=False)
def custom_docs():
    return HTMLResponse(f"""
<!DOCTYPE html>
<html><head>
<title>Content Moderation Queue — API Docs</title>
<meta charset="utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/swagger-ui-dist@5/swagger-ui.css">
<style>{SWAGGER_CSS}</style>
</head><body>
<div id="swagger-ui"></div>
<script src="https://cdn.jsdelivr.net/npm/swagger-ui-dist@5/swagger-ui-bundle.js"></script>
<script>
SwaggerUIBundle({{
    url: '/openapi.json',
    dom_id: '#swagger-ui',
    presets: [SwaggerUIBundle.presets.apis, SwaggerUIBundle.SwaggerUIStandalonePreset],
    layout: "BaseLayout",
    defaultModelsExpandDepth: 1,
    docExpansion: "list",
}})
</script>
</body></html>
""")


# ═══════════════════════════════════════════════════════════════════════════
# API Endpoints
# ═══════════════════════════════════════════════════════════════════════════

@app.get("/health")
def health():
    """Liveness probe — returns 200 when server is ready."""
    return {"status": "ok", "environment": "content-moderation-queue", "version": "1.0.0"}


@app.get("/tasks")
def list_tasks():
    """List all available tasks with metadata."""
    return {"tasks": _shared_env.list_tasks()}


@app.post("/reset", response_model=Observation)
def reset(
    task_id: str = Query(default="task_easy", description="One of: task_easy, task_medium, task_hard"),
    seed: Optional[int] = Query(default=None, description="Seed for post order. None=random each episode, integer=fixed reproducible order"),
):
    """
    Start a new episode. Creates an **isolated session** for you.

    - **task_id**: Which task to run (task_easy | task_medium | task_hard)
    - **seed**: Optional. Omit for random post order (RL training). Pass integer (e.g. 42) for reproducible order.

    The response includes a **session_id** — copy it and pass it to every `/step` and `/state` call.
    """
    try:
        sid, env = _new_session()
        obs = env.reset(task_id=task_id, seed=seed, session_id=sid)
        return obs
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))


@app.post("/step", response_model=StepResult)
def step(
    action: Action,
    session_id: str = Query(..., description="session_id from /reset response"),
):
    """
    Submit a moderation decision for the current post in your session.

    **Action fields:**
    - `action_type`: One of approve / warn / remove / ban_temporary / ban_permanent / escalate
    - `reasoning`: Optional explanation (logged, not graded)
    - `violation_type`: Optional — spam / hate_speech / harassment / misinformation / csam / illegal_services / doxxing / self_harm_risk / none

    Returns the next Observation, reward (0.0-1.0), done flag, and info dict.
    """
    env = _get_session(session_id)
    try:
        return env.step(action)
    except RuntimeError as e:
        raise HTTPException(status_code=400, detail=str(e))


@app.get("/state", response_model=EnvironmentState)
def state(
    session_id: str = Query(..., description="session_id from /reset response"),
):
    """
    Return a full snapshot of your session's current state.
    Includes step count, cumulative reward, all decisions, and final_score once done.
    """
    env = _get_session(session_id)
    return env.state()