When I first finished the architecture for my Polymarket trading bot, everything looked clean on paper.
Data flowed through clear pipelines, execution was isolated, and state was fully event-driven.
Then I ran it in production.
That’s when the system stopped behaving like a design diagram and started behaving like a distributed system in the real world - noisy, inconsistent, and occasionally wrong in ways that were hard to detect.
This post breaks down the most important production issues I encountered and how they changed the way I think about building trading systems.
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1. WebSockets are fast, but not reliable
The system relied on WebSockets for real-time wallet activity and market updates.
Initially, I treated them as a real-time source of truth.
That assumption broke quickly.
What actually happened
- Connections dropped without clear errors
- Messages arrived out of order during volatility spikes
- Some updates were silently missing
- Reconnects caused short data gaps that went unnoticed
The worst part was not failure - it was partial correctness.
The system would look fine while quietly drifting out of sync.
Why this is dangerous
Missing a single event leads to:
- incorrect position reconstruction
- duplicated trades
- wrong exposure calculations
Small inconsistencies compound quickly in trading systems.
Fix
- WebSockets became a fast signal layer
- REST API became a reconciliation layer
- periodic full-state refresh added
- heartbeat monitoring introduced
- automatic resync on detected gaps
Key shift
WebSockets are for speed, not correctness.
2. Execution drift slowly corrupted position accuracy
Execution was not failing outright.
It was behaving slightly differently than expected.
What I observed
- orders filled at different prices
- partial fills were common in thin liquidity markets
- replication diverged from target wallets
- slippage accumulated over time
Why this matters
Prediction markets have:
- thin liquidity
- nonlinear price impact
- fast sentiment shifts
Small execution errors become meaningful quickly.
Fix
- slippage estimation before trades
- liquidity-aware sizing
- strict caps per trade
- post-fill reconciliation
Key insight
Execution is probabilistic, not deterministic.
3. Copy trading is not actually copying
Originally:
Copy every trade from wallets.
That breaks almost immediately.
What broke
- split transactions across multiple orders
- rapid position flipping
- partial fills causing mismatches
- timing differences between systems
Fix
- aggregate trades in time windows
- compute net position delta
- replicate exposure instead of raw actions
Key insight
You don’t copy trades - you copy intent.
4. APIs don’t fail - they degrade
What happened
- responses slowed under load
- stale data was returned
- silent throttling occurred
- no clear error signals
Fix
- freshness timestamps on all data
- staleness thresholds for trading decisions
- fallback caching layer
- latency monitoring
Key insight
Stale data is worse than missing data.
5. State drift is inevitable without correction
Even with good architecture, state divergence appeared over time.
Symptoms
- incorrect positions
- duplicate exposure
- mismatch with real Polymarket state
Fix
- periodic reconciliation loop
- full state rebuild from source
- diff-based correction system
Key insight
State must be continuously verified against reality.
6. Risk management failed because it was static
What failed
- fixed exposure limits
- static stop-loss rules
- rigid position sizing
Fix
- liquidity-aware sizing
- volatility-based adjustments
- dynamic exposure caps
Key insight
Risk must adapt to market conditions, not remain fixed.
7. The biggest lesson
Production failures are rarely visible.
They do not crash systems.
They slowly degrade correctness.
Closing thought
The system did not break - it drifted away from reality.
Next step
Event sourcing and deterministic state reconstruction.