Stackone Unified Connectors

StackOne Unified Connectors

Build connectors that transform provider-specific data into standardized schemas with consistent field names, enum values, and pagination.

Skill Architecture

This is a baseline skill that provides the core workflow and patterns for building unified connectors. It is designed to work alongside domain-specific schema skills that you create for your organization's specific use cases.

Recommended approach:

1. Use this skill as your foundation for all unified connector work
2. Create domain-specific skills for each category you build connectors for (e.g., unified-hris-schema, unified-messaging-schema, unified-crm-schema)
3. Your domain-specific skills provide the schema definitions, field naming conventions, and enum value standards
4. This baseline skill provides the implementation patterns, CLI commands, and troubleshooting guidance

This separation allows you to maintain consistent schemas across all providers within a category while leveraging the shared technical patterns from this baseline skill.

Important

Before building unified connectors:

1. Read the CLI documentation: https://docs.stackone.com/guides/connector-engine/cli-reference
2. Use stackone help <command> for command-specific details
3. Always verify response structures with --debug before configuring mappings

Core Principles

These principles apply to ALL unified connector work. Violations cause silent failures or broken mappings.

1. All Config Field Names Use camelCase

Every YAML configuration field uses camelCase, not snake_case:

# CORRECT
scopeDefinitions:      fieldConfigs:         targetFieldKey:
enumMapper:            matchExpression:      dataKey:
nextKey:               pageSize:             indexField:
stepFunction:          functionName:         dataSource:

# WRONG - causes validation errors or silent failures
scope_definitions:     field_configs:        target_field_key:

2. Schema Field Names Use YOUR Naming Convention

While config fields are camelCase, targetFieldKey values match YOUR schema (often snake_case):

fieldConfigs:
  - targetFieldKey: first_name    # YOUR schema field
    expression: $.firstName       # Provider's field

3. Always Use Version '2' for map_fields and typecast

stepFunction:
  functionName: map_fields
  version: '2'          # REQUIRED - omitting causes empty results

4. Use Inline Fields in map_fields Parameters

Pass fields directly in map_fields step parameters rather than action-level fieldConfigs. This avoids schema inference issues that cause build failures.

# RECOMMENDED - Inline fields
- stepId: map_data
  stepFunction:
    functionName: map_fields
    version: '2'
    parameters:
      fields:
        - targetFieldKey: email
          expression: $.email           # Direct reference, NO step prefix
          type: string
      dataSource: $.steps.get_data.output.data

5. Expression Context Depends on Location

6. Never Suggest User-Side Mapping

The entire purpose of unified connectors is standardized output. Never suggest users handle mapping in application code.

7. Verify Every Path Against Raw Response

Never assume response structure. Always run with --debug first:

stackone run --debug --connector <file> --credentials <file> --action-id <action>

Instructions

Step 1: Resolve Schema

Check for a domain-specific schema skill first.

Domain-specific schema skills (e.g., unified-hris-schema, unified-crm-schema) should define your organization's standard schema for that category. These skills complement this baseline skill by providing:

• Target field names and types
• Enum values and their meanings
• Required vs optional fields
• Nested object structures

If schema skill exists:

• Use the schema definitions from that skill immediately
• Confirm which resource you're building (e.g., "employees", "contacts")
• Proceed to Step 2

If no schema skill exists:

• Ask user for schema in any format (YAML, JSON, markdown table, field list)
• Recommend creating a domain-specific schema skill for future builds in this category
• This ensures consistency across all providers you integrate

What a schema skill should contain:

# Example: unified-hris-schema skill structure
# - Field definitions with types
# - Enum values (e.g., employment_status: active, inactive, terminated)
# - Required fields marked
# - Nested structures documented

Creating domain-specific schema skills prevents drift between providers and reduces repeated schema discussions.

Step 2: Research Provider Endpoints (MANDATORY)

Do not skip this step. Research ALL available endpoints before proceeding.

For each endpoint, document:

• Field Coverage: Which schema fields does it return?
• Performance: Pagination support, rate limits
• Permissions: Required scopes (narrower is better)
• Deprecation: Never use deprecated endpoints

Step 3: Present Options to User (CHECKPOINT)

Present a comparison table and get explicit user approval before implementing:

| Option | Endpoint | Field Coverage | Permissions | Status |
|--------|----------|----------------|-------------|--------|
| A | GET /v2/employees | 70% | Narrow | Active |
| B | POST /reports | 100% | Moderate | Active |
| C | POST /v1/data | 100% | Broad | Deprecated |

Recommendation: Option B - Full coverage, not deprecated

Do not proceed without user selection.

Step 4: Configure Scopes

Use scopeDefinitions (not scope_definitions):

scopeDefinitions:
  employees:read:
    description: Read employee data
  employees:extended:read:
    description: Extended employee data
    includes: employees:read  # Scope inheritance

Principles:

• Narrower scopes always preferred
• Never use deprecated endpoints
• Document trade-offs explicitly

See references/scope-patterns.md for detailed patterns.

Step 5: Map Fields to Schema

Use inline fields in map_fields parameters:

steps:
  - stepId: map_data
    stepFunction:
      functionName: map_fields
      version: '2'
      parameters:
        fields:
          - targetFieldKey: id
            expression: $.id
            type: string
          - targetFieldKey: email
            expression: $.email
            type: string
          - targetFieldKey: department
            expression: $.work.department  # Nested field
            type: string
          - targetFieldKey: status
            expression: $.status
            type: enum
            enumMapper:
              matcher:
                - matchExpression: '{{$.status == "Active"}}'
                  value: active
                - matchExpression: '{{$.status == "Inactive"}}'
                  value: inactive
                - matchExpression: '{{$.status == null}}'
                  value: unknown
        dataSource: $.steps.get_data.output.data

  - stepId: typecast_data
    stepFunction:
      functionName: typecast
      version: '2'
      parameters:
        fields:
          - targetFieldKey: id
            type: string
          - targetFieldKey: email
            type: string
          - targetFieldKey: department
            type: string
          - targetFieldKey: status
            type: enum
        dataSource: $.steps.map_data.output.data

result:
  data: $.steps.typecast_data.output.data

See references/field-mapping-patterns.md for enum mapping, nested objects, and transformations.

Step 6: Configure Pagination

For list endpoints, use cursor pagination with the request function:

cursor:
  enabled: true
  pageSize: 50

inputs:
  - name: page_size
    type: number
    in: query
    required: false
  - name: cursor
    type: string
    in: query
    required: false

steps:
  - stepId: get_data
    stepFunction:
      functionName: request
      parameters:
        url: /items
        method: get
        args:
          # Dual-condition pattern for defaults
          - name: limit
            value: $.inputs.page_size
            in: query
            condition: "{{present(inputs.page_size)}}"
          - name: limit
            value: 50
            in: query
            condition: "{{!present(inputs.page_size)}}"
          - name: cursor
            value: $.inputs.cursor
            in: query
            condition: "{{present(inputs.cursor)}}"

result:
  data: $.steps.get_data.output.data
  next: $.steps.get_data.output.data.meta.nextCursor

Important: Use request function (not paginated_request) when you need dynamic inputs like page_size. The paginated_request function can have issues with $.inputs.* resolving to undefined.

See references/pagination-patterns.md for detailed configuration.

Step 7: Validate Configuration

stackone validate connectors/<provider>/<provider>.connector.s1.yaml

Step 8: Test Mappings

Phase 1: Raw Response

stackone run --debug --connector <file> --credentials <file> --action-id <action>

Phase 2: Field Mapping - Verify all fields use YOUR schema names, not provider names

Phase 3: Pagination - Test first page, next page, last page, empty results

Phase 4: Schema Completeness - All required fields present and populated

Step 9: Document Coverage

Create a coverage document listing:

• Required fields: mapped status
• Optional fields: mapped or documented why not
• Scopes required
• Limitations

Examples

Example 1: Building a unified employee connector (with schema skill)

User says: "start unified build for BambooHR"

Actions:

1. Check for domain-specific schema skill (e.g., unified-hris-schema)
2. If skill exists: Load employee schema from skill, confirm fields, proceed
3. If no skill: Ask for schema, recommend creating unified-hris-schema skill for consistency across HRIS providers
4. Research BambooHR endpoints: /v1/employees, /v1/employees/directory, custom reports
5. Present options with trade-offs (field coverage, scopes, deprecation)
6. After user selects, implement map_fields with inline fields using schema from skill
7. Configure pagination with cursor support
8. Test with --debug, verify field names match schema
9. Document coverage

Result: Working unified connector with standardized employee schema that matches other HRIS connectors.

Example 2: First connector in a new category

User says: "build a unified messaging connector for Slack"

Actions:

1. Check for unified-messaging-schema skill - none exists
2. Ask: "I don't see a messaging schema skill. What fields do you need for messages? I recommend we create a unified-messaging-schema skill so future messaging connectors (Teams, Discord) use the same schema."
3. Collaborate on schema definition
4. Suggest creating the schema skill before proceeding
5. Once schema is defined, proceed with standard workflow

Result: New schema skill created, connector built, future messaging connectors will use same schema.

Example 3: Debugging field mapping issues

User says: "My unified connector returns provider field names instead of my schema"

Actions:

1. Check if targetFieldKey uses YOUR schema names (not provider names)
2. Verify version: '2' is specified on map_fields and typecast
3. Check expression context - inline fields should NOT have step prefix
4. Run with --debug to see raw response structure
5. Verify dataSource path is correct

Result: Fields correctly mapped to user's schema.

Example 4: Pagination not working

User says: "Pagination cursor isn't being passed correctly"

Actions:

1. Run with --debug to see raw response structure
2. Verify dataKey path matches actual response (e.g., data.employees not just employees)
3. Verify nextKey path points to cursor value
4. Check if using paginated_request with dynamic inputs - switch to request with dual-condition pattern
5. Verify result.next returns the cursor value

Result: Working pagination with correct cursor handling.

Troubleshooting

Fields return provider names instead of schema names

Cause: Missing or incorrect field mapping configuration. Fix: Ensure targetFieldKey uses YOUR schema field names, not provider names. Verify map_fields step is present and dataSource is correct.

Mapping produces empty results

Cause: Missing version: '2' or wrong expression context. Fix: Add version: '2' to map_fields and typecast. For inline fields, use direct references ($.email) without step prefix.

Enum values not translating

Cause: matchExpression doesn't match provider values (case-sensitive). Fix: Check exact provider values with --debug. Use .toLowerCase() for case-insensitive matching. Always include null/unknown fallback.

Pagination returns same records

Cause: Cursor not being sent or extracted correctly. Fix: Verify iterator.key matches API's expected parameter name. Check nextKey path against raw response. Verify iterator.in is correct (query/body/headers).

Build fails with schema inference errors

Cause: Action-level fieldConfigs triggering unwanted schema inference. Fix: Use inline fields in map_fields parameters instead of action-level fieldConfigs.

Dynamic inputs resolve to undefined

Cause: Using paginated_request which doesn't handle $.inputs.* well. Fix: Use standard request function with dual-condition pattern for defaults.

Key URLs

Creating Domain-Specific Schema Skills

To maintain consistency across providers, create schema skills for each category you work with. A domain-specific schema skill should include:

Required content:

• Field definitions with types (string, number, boolean, datetime_string, enum)
• Enum value definitions with descriptions
• Required vs optional field indicators
• Nested object structures

Example skill structure:

# Unified HRIS Schema

## Employee Resource

### Required Fields
| Field | Type | Description |
|-------|------|-------------|
| id | string | Unique identifier |
| email | string | Primary email address |
| first_name | string | Employee first name |
| last_name | string | Employee last name |
| employment_status | enum | Current employment status |

### Enum: employment_status
| Value | Description |
|-------|-------------|
| active | Currently employed |
| inactive | On leave or suspended |
| terminated | No longer employed |

### Optional Fields
| Field | Type | Description |
|-------|------|-------------|
| department | string | Department name |
| hire_date | datetime_string | Date of hire |

Naming convention: unified-{category}-schema (e.g., unified-hris-schema, unified-crm-schema, unified-messaging-schema)

Related Skills

• stackone-cli: For deploying connectors and CLI commands
• stackone-connectors: For discovering existing connector capabilities
• stackone-agents: For building AI agents that use connectors
• Your domain-specific schema skills: For category-specific schemas (create as needed)