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Casatrick | Polymrket Bot Dev
Casatrick | Polymrket Bot Dev

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Polymarket WebSocket Reconnects: Rebuilding Trading State Safely

#polymarket #trading #rust #programming

Your Polymarket trading bot is connected to the WebSocket.

Then the connection drops.

A few seconds later, it reconnects.

Everything looks normal again.

But should the bot immediately start trading?

I don't think so.

A successful WebSocket reconnect only tells you that the connection has returned. It does not prove that the trading system has recovered the events it may have missed or that its local orders, fills, positions, and risk state are still correct.

The recovery problem is:

Disconnect
   ↓
Unknown state
   ↓
Reconnect
   ↓
Reconcile
   ↓
Verify
   ↓
Resume
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This is one of the problems I'm exploring with the Polymarket Trading Control Plane.

The project is an operational layer around automated Polymarket trading systems, focused on state, health, risk, reconciliation, and recovery.

A WebSocket reconnect is not a recovery

It's tempting to write something like:

WebSocket disconnected
       ↓
Reconnect
       ↓
Trading resumes
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That's fine for a simple data consumer.

For an automated trading system, there is a missing step.

What happened while the connection was unavailable?

Maybe an order changed state.

Maybe a fill occurred.

Maybe a position changed.

Maybe the application missed an event.

Maybe several events arrived in a different sequence.

The system cannot assume that reconnecting restores its internal state automatically.

A more defensive model is:

WebSocket disconnect
        ↓
Trading = PAUSED
        ↓
Reconnect
        ↓
Rebuild / reconcile state
        ↓
Verify orders
        ↓
Verify fills
        ↓
Verify positions
        ↓
Verify risk
        ↓
Trading = RESUMED
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That distinction is central to the Control Plane architecture.

What can happen during a disconnect?

Consider a simple sequence:

Event A
   ↓
WebSocket disconnect
   ↓
Events B, C, D
   ↓
WebSocket reconnect
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The local application may only know about A.

If B, C, and D affected trading state, local state is now incomplete.

For a trading bot, that can affect:

  • open orders
  • fills
  • positions
  • exposure
  • PnL
  • risk decisions

The process may still be running.

The problem is that it may no longer know the current state.

The dangerous part is that nothing has to crash

A crash is obvious.

A state discrepancy is not.

For example:

Process:       RUNNING
WebSocket:     CONNECTED
API:           OK
Strategy:      ACTIVE
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Everything looks healthy.

But:

Position state: UNVERIFIED
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That is a very different situation.

This is why I prefer distinguishing:

process health

from:

trading-system health.

The Control Plane currently models explicit operational states such as:

HEALTHY
DEGRADED
PAUSED
RECOVERING
FAILED
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rather than treating “process is alive” as the complete health model.

Why pause trading during the reconnect

Suppose the bot has no verified state during the disconnect.

If it keeps trading, its next decision could be based on:

stale positions
stale exposure
stale order state
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That creates a bad sequence:

Unknown state
    ↓
Strategy continues
    ↓
New order
    ↓
More exposure
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A safer approach is:

```text id="7t9r9d"
Unknown state
↓
No new risk
↓
Recovery
↓
Verified state
↓
Resume




The Control Plane's operational model explicitly includes `PAUSE TRADING`, `RESUME TRADING`, `KILL SWITCH`, and `RECONCILE STATE` as control actions.

---

## Reconnection should transition the system into recovery

I like thinking about reconnect as a state transition rather than a single callback.

For example:



```plaintext
HEALTHY
    ↓
WebSocket disconnect
    ↓
DEGRADED
    ↓
PAUSED
    ↓
RECONNECTING
    ↓
RECOVERING
    ↓
VERIFIED
    ↓
HEALTHY
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The exact implementation can vary.

The principle is:

The system should know which phase of recovery it is in.

That makes behavior easier to reason about and easier to observe.

Rebuild state after reconnect

Once the connection returns, the system needs a way to establish its current state.

Conceptually:

Reconnect
    ↓
Read current remote state
    ↓
Compare local state
    ↓
Repair discrepancies
    ↓
Verify
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This is different from simply subscribing to the stream again.

The Control Plane is designed around local-versus-remote state comparison for orders and positions, with reconciliation after reconnects, restarts, suspected event gaps, unexpected API responses, and mismatches.

What exactly should be reconciled?

Position is only one part of the problem.

The trading system has multiple related state domains:

Orders
   ↓
Trades / Fills
   ↓
Positions
   ↓
Exposure
   ↓
Risk
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That means recovery should not stop at:

“My position looks correct.”

It should eventually establish that the broader trading state is internally consistent.

For example:

Orders:      verified
Fills:       verified
Positions:   verified
Exposure:    verified
Risk:        verified
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Only then does the system have a strong basis for resuming normal operation.

The Control Plane explicitly treats these as separate observable state areas.

Missed events are not the only problem

A disconnect can create several types of uncertainty.

Missed event

The application never saw a state transition.

Duplicate event

The application processes the same event more than once.

Delayed event

The event arrives much later than expected.

Out-of-order state

The system observes related events in an unexpected sequence.

Restart during the gap

The application loses in-memory state before recovery.

That means the recovery layer has to be designed for uncertainty, not only connection failure.

Unknown should be an explicit state

One of the most useful states in a trading system is:

UNKNOWN
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Imagine the bot submits an order immediately before the connection drops.

The application doesn't know whether the order:

was rejected
was accepted
partially filled
fully filled
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The wrong behavior is to guess.

Instead:

UNKNOWN
   ↓
PAUSE
   ↓
RECONCILE
   ↓
DETERMINE ACTUAL STATE
   ↓
CONTINUE
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The Control Plane is designed around making uncertain state visible rather than hiding it.

Reconnect after a partial fill

This is where yesterday's Polymarket partial fills work connects directly to today's problem.

Imagine:

Requested: 100
Filled:     40
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Then the WebSocket disconnects.

During the gap, the remaining 60 may:

  • remain open
  • be cancelled
  • fill later
  • change execution state

The bot reconnects.

It should not assume:

Position = +40
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without checking.

And it should not assume:

Position = +100
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either.

It needs to reconcile.

That's why partial-fill handling and WebSocket recovery are separate but connected problems:

Partial Fill
     ↓
Execution State
     ↓
WebSocket Gap
     ↓
Potential State Drift
     ↓
Reconciliation
     ↓
Verified Position
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Reconnect after an application restart

The same problem appears during restart.

Suppose the process exits.

When it comes back, it has only the state that was persisted locally.

That state may not represent everything that happened while the application was down.

A safer startup path is:

Application starts
        ↓
Load local state
        ↓
    Connect
        ↓
Read remote state
        ↓
   Compare
        ↓
    Repair
        ↓
Verify risk
        ↓
Allow trading
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Starting the application and starting trading should therefore be two separate decisions.

The recovery sequence I want

The system I'm designing around this problem uses a simple mental model:

1. Detect
2. Pause
3. Reconnect
4. Reconcile
5. Repair
6. Verify
7. Check risk
8. Resume
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The purpose is not to make recovery slow.

The purpose is to avoid turning an infrastructure problem into an automated trading problem.

Risk needs to be part of recovery

Suppose the system reconciles positions successfully.

That still doesn't necessarily mean trading should immediately resume.

The system should also check:

  • current exposure
  • position limits
  • loss limits
  • data freshness
  • execution-failure count
  • overall health

The Control Plane's risk model explicitly includes position limits, market exposure, total exposure, daily loss, execution-failure limits, and stale-data conditions.

So the final recovery sequence becomes:

Reconcile
   ↓
Verify
   ↓
Risk Check
   ↓
ALLOW
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or:

Reconcile
   ↓
Mismatch / Risk Breach
   ↓
REMAIN PAUSED
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What if reconciliation fails?

This is important too.

Suppose the system reconnects but cannot establish a consistent state.

It should not keep trying to trade just because the connection is technically healthy.

Instead:

Reconnect
   ↓
Reconcile
   ↓
Mismatch remains
   ↓
PAUSED
   ↓
Alert operator
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The project is designed to make state mismatches and critical conditions observable so they can be handled deliberately.

The control plane architecture

This is the larger architecture I'm building around the trading bot:

                         POLYMARKET
                              │
               ┌──────────────┴──────────────┐
               │                             │
         WebSocket Streams              API / Reads
               │                             │
               ▼                             ▼
       ┌────────────────┐          ┌──────────────────┐
       │ Event Ingestion│          │ State Reconciler │
       └───────┬────────┘          └────────┬─────────┘
               │                            │
               └────────────┬───────────────┘
                            ▼
                    ┌──────────────────┐
                    │    State Store   │
                    │                  │
                    │ Orders           │
                    │ Trades           │
                    │ Positions        │
                    │ Exposure         │
                    │ PnL              │
                    │ Health           │
                    └────────┬─────────┘
                             │
              ┌──────────────┼──────────────┐
              ▼              ▼              ▼
         Risk Engine    Health Engine   Alert Engine
              │              │              │
              └──────────────┼──────────────┘
                             ▼
                    ┌──────────────────┐
                    │  Control Plane   │
                    │                  │
                    │ Pause            │
                    │ Resume           │
                    │ Kill Switch      │
                    │ Reconcile        │
                    └──────────────────┘
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This architecture is intentionally centered on operational state rather than another trading strategy.

Observability during recovery

Recovery shouldn't happen inside a black box.

The system should expose events such as:

WEBSOCKET_DISCONNECTED
RECONCILIATION_STARTED
STATE_MISMATCH
RECONCILIATION_COMPLETED
TRADING_PAUSED
TRADING_RESUMED
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The broader event model also includes:

ORDER_FAILURE
PARTIAL_FILL
MARKET_DATA_STALE
RISK_LIMIT_BREACHED
KILL_SWITCH_TRIGGERED
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That information can feed:

  • dashboards
  • logs
  • alerts
  • webhooks
  • external monitoring

Now an operator can see not only:

“The bot is connected.”

but:

“The bot reconnected, reconciled, verified state, passed risk checks, and resumed.”

That's a much more useful operational signal.

Failure scenarios worth testing

A WebSocket recovery implementation should be tested against more than a clean disconnect.

For example:

Scenario Expected behavior
WebSocket disconnect Enter degraded state
Reconnect Trigger recovery
Missed event Reconcile
Duplicate event Avoid double-counting
Delayed event Validate current state
Partial fill during gap Reconcile actual fill
Unknown order Block blind retry
Process restart Reload and reconcile
Position mismatch Pause trading
Risk breach Pause or kill

The Control Plane roadmap explicitly includes these kinds of failure and recovery scenarios.

Reconnect versus recovery

This distinction is the main idea of the project.

Reconnect 

Can I connect to the stream again?
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Recovery 

Can I prove that my trading state is correct again?
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Those are not the same question.

A reconnect can take seconds.

State recovery can require:

Event verification
+
State reconciliation
+
Position verification
+
Risk checks
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Only after that should normal trading resume.

Why I'm building this

The more I work on automated Polymarket trading, the more interesting the infrastructure around the strategy becomes.

The strategy answers:

What should I trade?

The execution layer answers:

How should I place the order?

The execution verifier answers:

What actually happened?

The control plane answers:

Can I safely continue?

That separation is the direction I'm exploring across these projects.

Related Polymarket projects

Polymarket Trading Bot

Automated trading, execution, risk controls, and backtesting.

https://github.com/casatrickdev/polymarket-trading-bot

Polymarket Execution Verifier

Verifies the execution lifecycle across:

Order
 ↓
Fill
 ↓
Transaction
 ↓
Settlement
 ↓
Position
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https://github.com/casatrickdev/polymarket-execution-verifier

Polymarket Trading Control Plane

Monitoring, state, reconciliation, risk, health, alerts, and recovery.

https://github.com/casatrickdev/polymarket-trading-control-plane

Together:

Trading Bot
    ↓
Execution
    ↓
Execution Verification
    ↓
State Reconciliation
    ↓
Control Plane
    ↓
Risk / Recovery
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Final takeaway

A WebSocket reconnect can tell you:

“The connection is back.”

It cannot automatically tell you:

“The trading system is healthy again.”

The system may have missed events.

Local state may be stale.

Orders may be uncertain.

Positions may need reconciliation.

Risk may have changed.

So the recovery path I want to build around is:

DISCONNECT
    ↓
PAUSE
    ↓
RECONNECT
    ↓
RECONCILE
    ↓
VERIFY
    ↓
RISK CHECK
    ↓
RESUME
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For an automated Polymarket trading bot, reconnecting is a networking problem. Recovering safely is a trading-system problem.

That's the distinction behind the Control Plane.

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