fix(snapshot): changed insert to upsert when concurrent identical child workflows are running

[waleedlatif1]

Summary

• changed insert to upsert when concurrent identical child workflows are running to avoid insertion conflicts

Type of Change

• Bug fix

Testing

Tested manually

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Feb 19, 2026 9:13pm

[greptile-apps]

Greptile Summary

Fixes race condition in concurrent snapshot creation by replacing SELECT-then-INSERT pattern with atomic upsert operation.

Key changes:

• Removed getSnapshotByHash query + manual UPDATE in favor of INSERT ... ON CONFLICT DO UPDATE
• Added logic to detect if snapshot is new by comparing returned ID with generated ID
• Enhanced logging to differentiate between new and reused snapshots
• Added comprehensive tests covering concurrent execution scenarios
• Simplified code by eliminating separate SELECT query

Confidence Score: 5/5

• Safe to merge - solid race condition fix with comprehensive tests
• Clean implementation that replaces problematic check-then-act pattern with atomic upsert. Well-tested with concurrent execution scenarios.
• No files require special attention

Important Files Changed

Filename	Overview
apps/sim/lib/logs/execution/snapshot/service.ts	Replaced SELECT-then-INSERT pattern with atomic upsert to prevent race conditions
apps/sim/lib/logs/execution/snapshot/service.test.ts	Added comprehensive tests for upsert behavior including concurrency scenarios

Sequence Diagram

sequenceDiagram
    participant C1 as Concurrent Request 1
    participant C2 as Concurrent Request 2
    participant DB as PostgreSQL Database
    
    Note over C1,C2: Both compute same stateHash for identical workflows
    
    C1->>DB: INSERT with UUID-1<br/>ON CONFLICT (workflowId, stateHash)<br/>DO UPDATE SET stateData
    C2->>DB: INSERT with UUID-2<br/>ON CONFLICT (workflowId, stateHash)<br/>DO UPDATE SET stateData
    
    Note over DB: Unique index on (workflowId, stateHash)<br/>ensures atomicity
    
    alt First request wins
        DB-->>C1: Returns snapshot with UUID-1
        DB-->>C2: Returns existing snapshot with UUID-1
        Note over C1: isNew = true (UUID matches)
        Note over C2: isNew = false (UUID differs)
    else Second request wins
        DB-->>C2: Returns snapshot with UUID-2
        DB-->>C1: Returns existing snapshot with UUID-2
        Note over C2: isNew = true (UUID matches)
        Note over C1: isNew = false (UUID differs)
    end

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[waleedlatif1]

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