spartanlabsxyz/simmer-sdk/polymarket-mert-sniper

Mert Sniper

Near-expiry conviction trading on Polymarket. The skill scans markets in their final minutes of pricing, filters for strongly-skewed splits, and places bounded trades against the under-priced side.

🚨 Framework, not a production trading system. Read DISCLAIMER.md before connecting to a wallet with real funds. Dry-run is the default; --live is required for any real-USDC trade. Defaults: $10 max per trade, 60/40 split minimum, 8-minute expiry window, 5 trades per scan cycle — adjust deliberately before scaling.

This is a template. The default logic (expiry + split filter) is a starting point — remix it with your own filters, timing rules, or market selection criteria. The skill handles all the plumbing (market discovery, trade execution, safeguards). Your agent provides the alpha.

Strategy attribution: @mert — see source thread for the original methodology (topic filter, near-expiry timing, strong-split entry).

News-recency veto. Optional guard that checks Simmer's macro-news schedule before order placement and skips matching news-resolution markets inside the first 30 seconds after CPI, BLS jobs/unemployment, FOMC, nonfarm payrolls, or quarterly earnings events. Continuous-feed crypto Up/Down markets are not blocked by this veto. Default is off until internal positive backfill coverage exists; set enable_news_veto=true to enable it.

Setup Flow

1. Install the Simmer SDK

``bash pip install simmer-sdk ``

1. Ask for Simmer API key

• Get it from simmer.markets/dashboard -> SDK tab
• Store in environment as SIMMER_API_KEY

1. Ask for wallet private key (required for live trading)

• This is the private key for their Polymarket wallet (the wallet that holds USDC)
• Store in environment as WALLET_PRIVATE_KEY
• The SDK uses this to sign orders client-side automatically — no manual signing needed

1. Ask about settings (or confirm defaults)

• Market filter: Which markets to scan (default: all)
• Max bet: Maximum per trade (default $10)
• Expiry window: How close to resolution (default 8 minutes)
• Min split: Minimum odds skew (default 60/40)

1. Save settings to config.json or environment variables

Configuration

Quick Commands

# Check account balance and positions
python scripts/status.py
 
# Detailed position list
python scripts/status.py --positions

API Reference:

• Base URL: https://api.simmer.markets
• Auth: Authorization: Bearer $SIMMER_API_KEY
• Portfolio: GET /api/sdk/portfolio
• Positions: GET /api/sdk/positions

Running the Skill

# Dry run (default -- shows opportunities, no trades)
python mert_sniper.py
 
# Execute real trades
python mert_sniper.py --live
 
# Filter to specific markets
python mert_sniper.py --filter solana
 
# Custom expiry window (5 minutes)
python mert_sniper.py --expiry 5
 
# With smart position sizing (uses portfolio balance)
python mert_sniper.py --live --smart-sizing
 
# Check positions only
python mert_sniper.py --positions
 
# View config
python mert_sniper.py --config
 
# Disable safeguards (not recommended)
python mert_sniper.py --no-safeguards

How It Works

Each cycle the script:

1. Fetches active markets from Simmer API (optionally filtered by tag/keyword)
2. Filters to markets resolving within the expiry window (default 8 minutes)
3. Checks the price split -- only trades when one side >= min_split (default 60%)
4. Determines direction: backs the favored side (higher probability)
5. Fee logging: prints entry-fee cost per market (POLY_FEE_RATE_CRYPTO × p × (1-p), entry only — redemption is free). If SIMMER_MERT_MIN_EDGE > 0, gates out markets where declared edge < entry fee + buffer
6. Safeguards: Checks context for flip-flop warnings, slippage, market status
7. Execution: Places trade on the favored side, capped at max bet
8. Reports summary of scanned, filtered, and traded markets

Example Output

🎯 Mert Sniper - Near-Expiry Conviction Trading
==================================================
 
  [DRY RUN] No trades will be executed. Use --live to enable trading.
 
  Configuration:
  Filter:        solana
  Max bet:       $10.00
  Expiry window: 8 minutes
  Min split:     60/40
  Max trades:    5
  Smart sizing:  Disabled
  Safeguards:    Enabled
 
  Fetching markets (filter: solana)...
  Found 12 active markets
 
  Markets expiring within 8 minutes: 2
 
  SOL highest price on Feb 10?
     Resolves in: 1m 34s
     Split: YES 72% / NO 28%
     Side: YES (72% >= 60%)
     [DRY RUN] Would buy $10.00 on YES
 
  Summary:
  Markets scanned: 12
  Near expiry:     2
  Strong split:    1
  Trades executed: 0
 
  [DRY RUN MODE - no real trades executed]

Troubleshooting

"No markets found"

• Check your filter -- try without a filter first
• Markets may not be available (check simmer.markets)

"No markets expiring within window"

• Increase expiry window: --expiry 10 (10 minutes)
• Or run more frequently (cron every minute)

"Split too narrow"

• Lower the min split: --set min_split=0.55
• This trades more often but with less conviction

"Resolves in: 17h" on 15-min markets

• Polymarket's endDate is the event-level end-of-day, not the individual market close time
• For 15-min crypto markets (e.g. "BTC Up or Down - Feb 8, 11PM ET"), the actual close time is in the question text but not in the API
• This is a Polymarket data limitation — widen the expiry window (--expiry 1080) as a workaround, or use the split filter to find conviction opportunities regardless of timing

"External wallet requires a pre-signed order"

• WALLET_PRIVATE_KEY is not set in the environment
• The SDK signs orders automatically when this env var is present — no manual signing code needed
• Fix: export WALLET_PRIVATE_KEY=0x<your-polymarket-wallet-private-key>
• Do NOT attempt to sign orders manually or modify the skill code — the SDK handles it

"Balance shows $0 but I have funds on Polygon"

• Polymarket V2 (live 2026-04-28) uses pUSD (PolyUSD, 1:1 backed by USDC.e). If your wallet holds USDC.e, migrate at simmer.markets/dashboard with one click (~30s)
• If you bridged native USDC (Circle), swap to USDC.e first, then migrate to pUSD
• Full migration guide: docs.simmer.markets/v2-migration

"API key invalid"

• Get new key from simmer.markets/dashboard -> SDK tab