# `react-doctor/duplicate-jsx-subtree`
Substantial JSX structure repeats across distinct React composition roots and may belong in a shared component
- **Status:** Active
- **Category:** Maintainability
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context, product intent
- **Default configuration:** Enabled
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** React projects
- **Priority:** 52 (P2)
- **Source:** react-doctor-core
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://www.react.doctor/docs/overview/react-maintainability)
## Validation prompt
Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.
This project-level check fingerprints JSX trees with at least 6 nodes and depth 3, groups structurally equivalent trees across distinct component roots, and reports maximal families with at least two occurrences. It normalizes data leaves while preserving component names, expression structure, member paths, and operators. Confirm the copies represent the same UI concept and would benefit from one interface. Reject when the resemblance is incidental, the variants are likely to evolve independently, or extraction would require a broad prop surface. Use the related locations and lexical composition paths to inspect every copy before deciding.
## Evidence boundary
The diagnostic proves only that the detector's modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.
Establish the environment, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.
Default severity is registry metadata. Use the occurrence's JSON severity after repository configuration when ordering real findings.
Record one outcome:
- **Confirmed failure:** The required evidence establishes the violation.
- **Rejected:** A documented exception or false-positive predicate applies.
- **Needs evidence:** Named evidence can still be collected.
- **Unavailable:** Required evidence cannot be collected in this run.
- **Waived with evidence:** An authorized, scoped exception applies to an established failure.
- **Observation:** The review records an optional tradeoff without claiming a defect.
A waiver records its scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.
## Review a candidate correction
Apply this candidate correction only after the required evidence confirms the risk.
### Reported pattern
```tsx
const RevenueCard = () => (
);
const OrdersCard = () => (
);
```
### Candidate corrected pattern
```tsx
const MetricCard = ({ title, value }: MetricCardProps) => (
);
const Dashboard = () => (
<>
);
```
## Fix prompt
Apply this candidate correction only after the required evidence confirms the risk.
Extract one shared component only after confirming the copies represent the same UI concept. Choose props for meaningful data or behavior differences, keep composition points explicit, and replace every reported copy without changing rendering, event behavior, semantics, or accessibility. Re-run React Doctor across the project to confirm the duplicate family is gone and no new diagnostics were introduced.
## Repository-wide copy prompt
Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.
````text
Fix every confirmed `react-doctor/duplicate-jsx-subtree` diagnostic in the current repository.
Required change:
- Extract one shared component only after confirming the copies represent the same UI concept. Choose props for meaningful data or behavior differences, keep composition points explicit, and replace every reported copy without changing rendering, event behavior, semantics, or accessibility. Re-run React Doctor across the project to confirm the duplicate family is gone and no new diagnostics were introduced.
Validation before editing:
This project-level check fingerprints JSX trees with at least 6 nodes and depth 3, groups structurally equivalent trees across distinct component roots, and reports maximal families with at least two occurrences. It normalizes data leaves while preserving component names, expression structure, member paths, and operators. Confirm the copies represent the same UI concept and would benefit from one interface. Reject when the resemblance is incidental, the variants are likely to evolve independently, or extraction would require a broad prop surface. Use the related locations and lexical composition paths to inspect every copy before deciding.
Constraints:
- Confirm every occurrence independently.
- Make the smallest change that addresses the root cause.
- Preserve unrelated behavior, interfaces, content, and semantics.
- Reuse existing project conventions and components.
- Do not suppress the rule merely to clear the report.
Assessment:
- Record detector evidence, applicability, missing evidence, and one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
Verification:
- Run focused tests and every repository-mandated check.
- Run React Doctor and confirm the diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report checks that were not run instead of claiming they passed.
````