> ## Documentation Index
> Fetch the complete documentation index at: https://docs.barndoor.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Compare Policy Revisions

> Compare two revisions of a policy.

Returns the before/after state, a diff of changes, change categories,
and the union of resolved_refs from both endpoint revisions.
The before/after are always normalized so before is the older revision.



## OpenAPI

````yaml /api-reference/openapi.yaml get /api/policy/v2/policies/{policy_id}/revisions/compare
openapi: 3.1.0
info:
  title: Barndoor.ai Public API
  description: Unified public API specification for Barndoor.ai platform
  version: 2.18.0
servers:
  - url: https://{host}
    description: Barndoor public API
    variables:
      host:
        default: platform.barndoor.ai
        description: >-
          The host serving your Barndoor deployment. Defaults to production;
          override it for another environment or a dedicated deployment.
security:
  - ApiKey: []
  - OAuth2:
      - openid
      - profile
      - email
tags:
  - name: dlp
    x-group: Data Control Center
  - name: identity
    x-group: Identity
  - name: llm-gateway
    x-group: LLM Gateway
  - name: notification
    x-group: Notifications
  - name: policy
    x-group: Policies
  - name: registry
    x-group: MCP Gateway
  - name: system-management
    x-group: Log Exports
paths:
  /api/policy/v2/policies/{policy_id}/revisions/compare:
    get:
      tags:
        - policy
      summary: Compare Policy Revisions
      description: |-
        Compare two revisions of a policy.

        Returns the before/after state, a diff of changes, change categories,
        and the union of resolved_refs from both endpoint revisions.
        The before/after are always normalized so before is the older revision.
      operationId: compare_policy_revisions
      parameters:
        - name: policy_id
          in: path
          required: true
          schema:
            type: string
            title: Policy Id
        - name: from
          in: query
          required: true
          schema:
            type: string
            title: From
        - name: to
          in: query
          required: true
          schema:
            type: string
            title: To
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PolicyRevisionCompareResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
components:
  schemas:
    PolicyRevisionCompareResponse:
      properties:
        before:
          $ref: '#/components/schemas/PolicyRevisionCompareSide'
        after:
          $ref: '#/components/schemas/PolicyRevisionCompareSide'
        changes:
          additionalProperties: true
          type: object
          title: Changes
        categories:
          items:
            type: string
          type: array
          title: Categories
        resolved_refs:
          additionalProperties:
            $ref: '#/components/schemas/ResolvedRef'
          type: object
          title: Resolved Refs
        rule_titles:
          additionalProperties:
            type: string
          type: object
          title: Rule Titles
      type: object
      required:
        - before
        - after
        - changes
      title: PolicyRevisionCompareResponse
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    PolicyRevisionCompareSide:
      properties:
        revision_id:
          type: string
          format: uuid
          title: Revision Id
        revised_at:
          type: string
          format: date-time
          title: Revised At
        revised_by:
          type: string
          title: Revised By
        revised_by_name:
          anyOf:
            - type: string
            - type: 'null'
          title: Revised By Name
        triggered_by:
          anyOf:
            - type: string
            - type: 'null'
          title: Triggered By
        triggered_by_name:
          anyOf:
            - type: string
            - type: 'null'
          title: Triggered By Name
        version_number:
          type: integer
          title: Version Number
      type: object
      required:
        - revision_id
        - revised_at
        - revised_by
        - version_number
      title: PolicyRevisionCompareSide
    ResolvedRef:
      properties:
        name:
          type: string
          title: Name
        type:
          type: string
          enum:
            - mcp_server
            - application
          title: Type
      type: object
      required:
        - name
        - type
      title: ResolvedRef
      description: Aligns with design §4 — only two ref types are ever stored.
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    ApiKey:
      type: http
      scheme: bearer
      description: >-
        A Barndoor API key, sent as `Authorization: Bearer <key>`. Keys are
        prefixed `bdai_` and are opaque — do not attempt to decode one.
        Interchangeable with an OAuth 2.0 access token.
    OAuth2:
      type: oauth2
      x-issuer: https://auth.barndoor.ai/realms/barndoor
      description: >-
        An OAuth 2.0 access token from Barndoor's identity provider, sent as
        `Authorization: Bearer <token>`. Public clients must use PKCE.
        Interchangeable with an API key.
      flows:
        authorizationCode:
          authorizationUrl: >-
            https://auth.barndoor.ai/realms/barndoor/protocol/openid-connect/auth
          tokenUrl: >-
            https://auth.barndoor.ai/realms/barndoor/protocol/openid-connect/token
          scopes:
            openid: Issue an OIDC ID token identifying the caller.
            profile: Read the caller's basic profile claims.
            email: Read the caller's email address.
            offline_access: Issue a refresh token. Optional — no operation requires it.
        clientCredentials:
          tokenUrl: >-
            https://auth.barndoor.ai/realms/barndoor/protocol/openid-connect/token
          scopes:
            openid: Issue an OIDC ID token identifying the caller.
            profile: Read the caller's basic profile claims.
            email: Read the caller's email address.
            offline_access: Issue a refresh token. Optional — no operation requires it.

````

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