[Fusion] Fixed satisfiability issue with fields on the Query type

[glen-84]

Summary of the changes (Less than 80 chars)

• [Fusion] Fixed satisfiability issue with fields on the Query type.

[Copilot]

Pull request overview

This PR fixes a bug in the satisfiability validator that caused validation to fail when fields on the Query type (root type) had @require directives. The issue occurred because the code attempted to peek at the path stack when it was empty for root-level fields.

Changes:

• Fixed null handling when validating requirements on root Query type fields
• Made the parentPathItem parameter nullable throughout the validation chain
• Added test coverage for the root requirement scenario

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
SatisfiabilityValidator.cs	Changed to pass previousPathItem (which is null-safe) instead of calling context.Path.Peek() when validating requirements
RequirementsValidator.cs	Updated Validate method signature to accept nullable parentPathItem and modified constructor to conditionally push parent path item only when non-null
SatisfiabilityValidatorTests.cs	Added RootRequirement test case that verifies a Query field with @require directive referencing another Query field validates successfully

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[github-actions]

🚀 Fusion Gateway Performance Results

Simple Composite Query

Constant Load (50 VUs)

Requests/sec	Error Rate
5807.28 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
0.81ms	7.18ms	162.52ms	8.46ms	13.07ms	18.81ms

Ramping Load (0→50→500→50 VUs)

Requests/sec	Error Rate
4562.65 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
0.84ms	38.84ms	261.40ms	48.66ms	108.27ms	125.66ms

Executed Query

fragment User on User {
  id
  username
  name
}

fragment Review on Review {
  id
  body
}

fragment Product on Product {
  inStock
  name
  price
  shippingEstimate
  upc
  weight
}

query TestQuery {
  topProducts(first: 5) {
    ...Product
    reviews {
      ...Review
      author {
        ...User
      }
    }
  }
}

Deep Recursion Query

Constant Load (50 VUs)

Requests/sec	Error Rate
269.47 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
13.02ms	174.32ms	752.09ms	179.91ms	224.72ms	248.36ms

Ramping Load (0→50→500→50 VUs)

Requests/sec	Error Rate
299.87 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
3.09ms	706.18ms	1687.66ms	704.99ms	1401.17ms	1507.93ms

Executed Query

fragment User on User {
  id
  username
  name
}

fragment Review on Review {
  id
  body
}

fragment Product on Product {
  inStock
  name
  price
  shippingEstimate
  upc
  weight
}

query TestQuery {
  users {
    ...User
    reviews {
      ...Review
      product {
        ...Product
        reviews {
          ...Review
          author {
            ...User
            reviews {
              ...Review
              product {
                ...Product
              }
            }
          }
        }
      }
    }
  }
  topProducts(first: 5) {
    ...Product
    reviews {
      ...Review
      author {
        ...User
        reviews {
          ...Review
          product {
            ...Product
          }
        }
      }
    }
  }
}

Variable Batching Throughput

Constant Load (50 VUs)

Requests/sec	Error Rate
23708.81 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
0.09ms	1.70ms	45.78ms	2.06ms	3.92ms	4.80ms

Ramping Load (0→50→500→50 VUs)

Requests/sec	Error Rate
18672.75 req/s	0.00%

📊 Response Time Metrics

Min	Med	Max	Avg	P90	P95
0.09ms	9.28ms	107.79ms	11.26ms	23.16ms	27.94ms

Executed Query

query TestQuery_8f7a46ce_2(
  $__fusion_1_upc: ID!
  $__fusion_2_price: Long!
  $__fusion_2_weight: Long!
) {
  productByUpc(upc: $__fusion_1_upc) {
    inStock
    shippingEstimate(weight: $__fusion_2_weight, price: $__fusion_2_price)
  }
}

Variables (5 sets batched in single request)

[
  { "__fusion_1_upc": "1", "__fusion_2_price": 899, "__fusion_2_weight": 100 },
  { "__fusion_1_upc": "2", "__fusion_2_price": 1299, "__fusion_2_weight": 1000 },
  { "__fusion_1_upc": "3", "__fusion_2_price": 15, "__fusion_2_weight": 20 },
  { "__fusion_1_upc": "4", "__fusion_2_price": 499, "__fusion_2_weight": 100 },
  { "__fusion_1_upc": "5", "__fusion_2_price": 1299, "__fusion_2_weight": 1000 }
]

No baseline data available for comparison.

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Run 21479822483 • Commit 4233a58 • Thu, 29 Jan 2026 13:41:29 GMT