fix: Handle missing segments from ImpactedFileComparison response

[calvin-codecov]

Related to problem happening in: https://sentry.zendesk.com/agent/tickets/171579 where the customer's pull request has coverage data showing but displays a 400 error on the page with no useful information.

Our query ImpactedFileComparison is getting a 404 when trying to request the source code from the git provider for a specific file when expanding in the UI. This PR is adding better handling of the response from the query when it does not return segments of type SegmentComparisons (what we need to display the snippets with coverage) but instead UnknownPath or ProviderError. We are getting UnknownPath in this customer's case. These changes add UI components that mirror what we show for CommitDiff that get UnknownPath/ProviderError responses. Other files change include newly checking the segments part of the GQL response data to dictate behavior as opposed to moving straight segments?.results and dealing with undefineds.

---

Note

Improves robustness of impacted-file diff rendering when GraphQL segments isn’t SegmentComparisons.

• Updates schemas to a discriminated union for segments (SegmentComparisons | UnknownPath | ProviderError) in services/pull/fragments and preserves full segments in transform utils
• Guards all segment-to-line-data mappers to check segments.__typename === 'SegmentComparisons' before using .results
• Pull request views (PullFileDiff for FilesChanged/IndirectChanges) now handle UnknownPath with a user-facing message and ProviderError with a generic error; similar handling added/confirmed for commit views
• useSingularImpactedFileComparison returns raw impactedFile (no early transform); consumers call transformImpactedPullFileToDiff
• Tests added/updated to cover UnknownPath and new data shape expectations

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[sentry]

❌ 5 Tests Failed:

Tests completed	Failed	Passed	Skipped
1783	5	1778	0

View the top 3 failed test(s) by shortest run time

src/services/pull/utils/transformImpactedPullFileToDiff.test.ts > transformImpactedPullFileToDiff > returns file information

Stack Traces | 0.00953s run time

AssertionError: expected { fileLabel: null, …(3) } to strictly equal { fileLabel: null, …(3) }

- Expected
+ Received

  Object {
    "fileLabel": null,
    "hashedPath": "hashedPath",
    "headName": "headName",
-   "segments": Array [
+   "segments": Object {
+     "results": Array [
        Object {
          "hasUnintendedChanges": false,
          "header": "header",
          "lines": Array [
            Object {
              "baseCoverage": "M",
              "baseNumber": "1",
              "content": "content",
              "headCoverage": "H",
              "headNumber": "1",
            },
          ],
        },
      ],
+   },
  }

 ❯ .../pull/utils/transformImpactedPullFileToDiff.test.ts:40:18

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a renamed file > queries the api

Stack Traces | 0.0172s run time

AssertionError: expected undefined to strictly equal { fileLabel: 'Renamed', …(3) }

- Expected: 
Object {
  "fileLabel": "Renamed",
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:283:22

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a unchanged file label > queries the api

Stack Traces | 0.019s run time

AssertionError: expected undefined to strictly equal { fileLabel: null, …(3) }

- Expected: 
Object {
  "fileLabel": null,
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:353:22

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a deleted file > queries the api

Stack Traces | 0.0267s run time

AssertionError: expected undefined to strictly equal { fileLabel: 'Deleted', …(3) }

- Expected: 
Object {
  "fileLabel": "Deleted",
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:318:22

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a normal pull diff > queries the api

Stack Traces | 0.0976s run time

AssertionError: expected undefined to strictly equal { fileLabel: 'New', …(3) }

- Expected: 
Object {
  "fileLabel": "New",
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:248:22

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[codecov-public-qa]

❌ 5 Tests Failed:

Tests completed	Failed	Passed	Skipped
1783	5	1778	0

View the top 3 failed test(s) by shortest run time

src/services/pull/utils/transformImpactedPullFileToDiff.test.ts > transformImpactedPullFileToDiff > returns file information

Stack Traces | 0.00953s run time

AssertionError: expected { fileLabel: null, …(3) } to strictly equal { fileLabel: null, …(3) }

- Expected
+ Received

  Object {
    "fileLabel": null,
    "hashedPath": "hashedPath",
    "headName": "headName",
-   "segments": Array [
+   "segments": Object {
+     "results": Array [
        Object {
          "hasUnintendedChanges": false,
          "header": "header",
          "lines": Array [
            Object {
              "baseCoverage": "M",
              "baseNumber": "1",
              "content": "content",
              "headCoverage": "H",
              "headNumber": "1",
            },
          ],
        },
      ],
+   },
  }

 ❯ .../pull/utils/transformImpactedPullFileToDiff.test.ts:40:18

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a renamed file > queries the api

Stack Traces | 0.0172s run time

AssertionError: expected undefined to strictly equal { fileLabel: 'Renamed', …(3) }

- Expected: 
Object {
  "fileLabel": "Renamed",
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:283:22

src/services/pull/usePrefetchSingleFileComp.test.tsx > usePrefetchSingleFileComp > successful request > when called with a unchanged file label > queries the api

Stack Traces | 0.019s run time

AssertionError: expected undefined to strictly equal { fileLabel: null, …(3) }

- Expected: 
Object {
  "fileLabel": null,
  "hashedPath": "hashed-path",
  "headName": "file A",
  "segments": Array [],
}

+ Received: 
undefined

 ❯ .../services/pull/usePrefetchSingleFileComp.test.tsx:353:22

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Identical component duplicated across multiple files

Low Severity

The UnknownPathErrorDisplayMessage component is defined identically in two separate PullFileDiff.tsx files in this PR. The same component also already exists in the CommitFileDiff files, resulting in four total copies of identical code. This increases maintenance burden and risks inconsistent bug fixes if the error message or styling needs to change. While this follows an existing pattern in the codebase (similar to ErrorDisplayMessage), extracting it to a shared location would reduce duplication.

Additional Locations (1)

• src/pages/PullRequestPage/PullCoverage/routes/IndirectChangesTab/PullFileDiff/PullFileDiff.tsx#L136-L166