Campaign Approval Workflow Before Scheduled Execution

Problem Statement

Currently, after a campaign is scheduled by an operator, it will run automatically at the scheduled time without any review or approval step. This creates a quality risk and responsibility gap, especially in teams with this structure:

• Operator/Intern: creates and schedules the campaign
• Manager/QA: accountable for campaign content quality and results

There is no mechanism to ensure a campaign passes quality gates before publication.

Proposed Solution

Add a Campaign Approval Workflow feature with the following specifications:

1. Campaign Status Enhancement

   • Add new status: pending_approval (in addition to existing: draft, scheduled, running, completed)
   • When an operator schedules a campaign, status changes to pending_approval instead of directly to scheduled

2. Approval Role & Permission

   • Add new permission: campaigns.approve
   • Users with specific roles (e.g., Manager/Admin) can approve or reject campaigns
   • Multiple users can approve based on assigned role

3. Approval Interface

   • In campaign detail view, add "Approval Status" section:
     • Approve button (changes status to scheduled, campaign runs at scheduled time)
     • Reject button (reverts to draft, operator can revise and resubmit)
     • Optional reason/notes field for approval or rejection
     • Audit trail: who approved/rejected, when, and reason

4. Optional Flow Toggle

   • Add setting at campaign type or global level: require_approval (true/false)
   • If false, approval workflow is skipped (current behavior — schedule runs immediately)
   • This makes the feature opt-in and backward compatible

5. Notification

   • Email or in-app notification to approvers when a campaign is pending approval
   • Notification to operator when campaign is approved or rejected

Acceptance Criteria

• Campaign approval status is visible in campaign list and detail view
• Users with campaigns.approve permission can approve/reject pending campaigns
• Approved campaigns run at scheduled time; rejected campaigns revert to draft
• Audit log records who approved/rejected, timestamp, and reason
• Approval requirement can be toggled per campaign or globally
• Notifications are sent to approver and operator
• Existing campaigns and workflows are unaffected (backward compatible)

Use Case

1. An intern/operator creates a campaign "Summer Promo" and schedules it for Friday at 10 AM
2. Campaign status → pending_approval
3. Manager receives notification "Campaign pending approval"
4. Manager reviews the campaign (subject, content, recipient list) in the dashboard
5. Manager Approves → campaign status → scheduled, campaign runs Friday at 10 AM
   • Or Rejects with reason "Typo in subject line" → campaign reverts to draft, operator revises and resubmits

Implementation Considerations

• Approval workflow could be enforced per campaign template or campaign type
• Could be extended to scheduled list imports, template approval, etc. (future enhancement)
• Consider webhook/API integration for approval automation (future)
• Minimal storage overhead for audit trail; scheduler logic needs update to check approval status before execution

Related Issues

• Reference #2327 (subscriber approval workflow) — similar concept, different scope

Contribution Intent

I am interested in implementing this feature and would like to contribute to this project. Before I start development, I would appreciate feedback on:

1. Design Approval: Is the proposed approach (status workflow, permission structure, notification flow) aligned with Listmonk's architecture?
2. Implementation Approach: Any specific patterns or libraries I should follow? (e.g., for audit logging, permission checking)
3. Database Schema: Should I prepare a migration approach for backward compatibility?
4. Timeline: Any constraints or priorities that would affect development?

I'm ready to open a draft PR for discussion once there's feedback on the design.