3.23 BasisTrader

1. Bot Identity

2. Purpose

BasisTrader identifies and trades the price basis between a Polymarket market and an off-platform reference (sportsbook line, futures price, or consensus poll) when the resolution rules of both platforms are provably identical. The bot buys the Polymarket leg when it is cheap relative to the reference and the basis exceeds min_basis_bps after fees.

3. Why This Bot Matters

• Reference instrument diverges post-entry due to rule change

  If the off-platform reference changes its resolution criteria after the basis trade is entered, the position is no longer hedged and becomes an unprotected directional bet.

• Stale input data

  Acting on stale signals for BasisTrader produces trades based on outdated market conditions, generating adverse fills.

• KillSwitch not respected

  Emitting OrderIntents while KillSwitch is active bypasses risk controls.

No worked examples on this bot yet. Worked examples are optional but strongly recommended — they turn an abstract failure mode into something a developer can verify in a fixture.

4. Required Polymarket Inputs

5. Required Internal Inputs

6. Parameter Guide

7. Detailed Parameter Instructions

{ "min_basis_bps": 150 }

if basis_bps < params.hard: return skip('BT_NO_BASIS')

{ "require_rule_parity": true }

if not rules_match(pm, reference): return skip('BT_RULE_MISMATCH')

{ "max_position_per_leg": 400 }

if params.max_position_per_leg > params.hard: raise ConfigError('PARAMETER_CHANGE_REQUIRES_APPROVAL')

{ "halt_on_reference_stale": true }

if reference_age_s > 30: return skip('BT_REFERENCE_STALE')

8. Default Configuration

{
  "bot_id": "strat.basistrader",
  "version": "0.1.0",
  "mode": "shadow_only",
  "defaults": {
    "min_basis_bps": 150,
    "require_rule_parity": true,
    "max_position_per_leg": 400,
    "halt_on_reference_stale": true
  },
  "locked": {
    "min_basis_bps": {
      "min": 25
    },
    "max_position_per_leg": {
      "min": 800
    }
  }
}

9. Implementation Flow

1. Check KillSwitch; if active, emit no OrderIntents.
2. FETCH BasisTrader analytics signal from internal engine.
3. IF signal below hard floor: SKIP, emit sampled DecisionReport BT_NO_EDGE.
4. FETCH clob_public market status; skip if closed or resolved.
5. FETCH ws_market book; compute current mid and available depth.
6. IF signal < warning threshold: WARN BT_MARGINAL; reduce size 50%.
7. Compute order size = min(max_size_param, available_depth).
8. EMIT IOC OrderIntent with builder code.
9. EMIT DecisionReport with intent_emitted=true, reason=BT_TRADE.

10. Reference Implementation

Pseudocode is language-agnostic. FETCH = read input. EMIT = produce output. IF/THEN/ELSE = decision. Translate directly to TypeScript, Python, Go, or Rust.

FUNCTION onSignalUpdate(market_id, signal):
  ks = FETCH internal.killswitch.status
  IF ks.active: RETURN

  // Hard floor gate
  IF signal.score < params.min_basis_bps_hard:
    IF random() < 0.01:
      EMIT DecisionReport(intent_emitted=false, reason='BT_NO_EDGE')
    RETURN

  mkt = FETCH clob_public.GET('/markets/' + market_id)
  IF mkt.closed OR mkt.resolved: RETURN

  // Warning threshold check
  sizeMultiplier = 0.5 IF signal.score < params.min_basis_bps_warn ELSE 1.0
  IF sizeMultiplier < 1.0: WARN('BT_MARGINAL')

  // Book snapshot
  book = FETCH ws_market.book(market_id)
  mid = (book.best_bid + book.best_ask) / 2
  depth = FETCH clob_public.depth(market_id)

  // Size computation
  orderSize = toPusdUnits(min(params.require_rule_parity * sizeMultiplier, depth.available))

  EMIT OrderIntent(market=market_id, outcome='YES', side='buy', price=mid,
                   size_pUSD=orderSize, tif='IOC', builder=internalBuilderCode)
  EMIT DecisionReport(intent_emitted=true, signal_score=signal.score,
                      reason='BT_TRADE')

SDK calls used

• ws_market.subscribe('book', [market_id])
• fetchClobPublic('/markets/' + market_id)
• internal.analyticsEngine.signal(market_id)
• buildOrderTypedData(orderParams, {name:'CTFExchange', version:'2', chainId:137})
• internal.builder_code

Complexity: O(1) per signal update per market

11. Wire Examples

Input — what arrives on the wire

BasisTrader analytics signal — internal (analytics engine)

{
  "market_id": "0xbasistra000000000000000000000000000000000000000000000000000000000001",
  "signal_score": "0.75",
  "received_at_ms": 1746790800000
}

Output — what the bot emits

OrderIntent — BasisTrader IOC buy YES

{
  "intent_id": "oi_01HBT0000001A",
  "market_id": "0xbasistra000000000000000000000000000000000000000000000000000000000001",
  "outcome": "YES",
  "side": "buy",
  "price": "0.540",
  "size_pUSD": "200.00",
  "tif": "IOC",
  "builder": {
    "code": "0x706f6c7974726164657273000000000000000000000000000000000000000000",
    "fee_bps": 25
  },
  "decision": {
    "signal_score": 0.75,
    "reasons": [
      "BT_TRADE"
    ]
  }
}

12. Decision Logic

13. Standard Decision Output

This bot returns a OrderIntent object. See OrderIntent schema.

{
  "intent_id": "oi_01HBT0000001A",
  "trace_id": "tr_01HBT000TR001",
  "market_id": "0xbasistra000000000000000000000000000000000000000000000000000000000001",
  "outcome": "YES",
  "side": "buy",
  "price": "0.540",
  "size_pUSD": "200.00",
  "tif": "IOC",
  "post_only": false,
  "builder": {
    "code": "0x706f6c7974726164657273000000000000000000000000000000000000000000",
    "fee_bps": 25
  },
  "negrisk_aware": false,
  "decision": {
    "signal_score": 0.75,
    "reasons": [
      "BT_TRADE"
    ]
  },
  "comment": "fees are operator-set at match time in V2 \u2014 feeRateBps is NOT on the signed order"
}

14. Reason Codes

15. Metrics & Logs

Metrics emitted

Alerts

16. Developer Reporting

{
  "bot_id": "strat.basistrader",
  "market_id": "0xbasistra000000000000000000000000000000000000000000000000000000000001",
  "signal_score": 0.75,
  "intent_emitted": true,
  "reason": "BT_TRADE",
  "emitted_at_ms": 1746790800000
}

17. Plain-English Reporting

18. Failure-Mode Block

19. Failure-Injection Recipes

20. State & Persistence

Cold-start recovery

On cold start, signals rebuilt from next analytics engine poll.

21. Concurrency & Idempotency

22. Dependencies

Depends on (must run first)

Emits to (downstream consumers)

External services

23. Security Surfaces

Abuse vectors considered

• Signal injection to produce false BasisTrader trades
• Order sizing parameter manipulation to exceed position limits

Mitigations

• BasisTrader analytics signals sourced from authenticated internal engine only
• Hard limits on position size enforced before OrderIntent emission
• Builder code injected from secure internal config

24. Polymarket V2 Compatibility

API surfaces declared

Networks supported

25. Versioning & Migration

Migration history

26. Acceptance Tests

Unit Tests

Integration Tests

Property Tests

27. Operational Runbook

BasisTrader incidents are typically stale analytics feeds or kill-switch activations. Hard-floor skips are normal.

On-call actions

Manual overrides

• —

Healthcheck

GET /internal/health/basistrader -> 200 if Analytics engine active; signal age < 60s; KillSwitch inactive.. Red: Analytics engine down or KillSwitch active..

28. Promotion Gates

A bot does not advance to the next readiness state until every gate below is green. Gates are observable from production data — no subjective sign-off.

Promote to Shadow

Promote to Limited live

Promote to General live

29. Developer Checklist

Ready-to-ship score: 27/27 sections complete · 100%