Dist White Hat Dedup

# apps/distribution/services.py
from apps.distribution.models import ShareJob

def create_job_if_not_exists(
    *, post, account, channel: str, plan=None, payload: dict | None = None,
) -> ShareJob | None:
    """Create a ShareJob only if no completed/pending job exists."""
    existing = ShareJob.objects.filter(
        post=post,
        account=account,
        channel=channel,
        status__in=["pending", "completed", "retrying"],
    ).exists()

    if existing:
        return None  # Already distributed or in progress

    return ShareJob.objects.create(
        post=post,
        account=account,
        channel=channel,
        plan=plan,
        payload=payload or {},
    )

Idempotent Execution Guard

def execute_job_idempotent(*, job: ShareJob) -> dict:
    """Execute job with idempotency — safe to call multiple times."""
    if job.status == "completed" and job.external_post_id:
        return {"status": "already_completed", "id": job.external_post_id}

    # Mark as in-progress to prevent concurrent execution
    updated = ShareJob.objects.filter(
        pk=job.pk, status="pending",
    ).update(status="in_progress")

    if updated == 0:
        # Another worker already picked this up
        return {"status": "already_processing"}

    job.refresh_from_db()
    return dispatch_to_connector(job=job)

Content Hash for Near-Duplicate Detection

import hashlib

def content_hash(text: str) -> str:
    """Generate hash of content for dedup comparison."""
    normalized = " ".join(text.lower().split())
    return hashlib.sha256(normalized.encode()).hexdigest()[:16]

def is_near_duplicate(*, post, channel: str) -> bool:
    """Check if similar content was recently posted to this channel."""
    recent_jobs = ShareJob.objects.filter(
        channel=channel, status="completed",
        created_at__gte=timezone.now() - timedelta(hours=24),
    )
    new_hash = content_hash(post.title + post.meta_description)
    for job in recent_jobs:
        old_hash = content_hash(job.payload.get("text", ""))
        if old_hash == new_hash:
            return True
    return False

Anti-Patterns

• No dedup — same blog post shared to Twitter 5 times on retries
• Relying on DB unique constraint alone — doesn't catch near-duplicates
• No external_post_id check — can't verify if post exists on platform
• Deleting failed jobs before retry — loses error context

Quality Gate

& .\.venv\Scripts\python.exe -m ruff check . --fix
& .\.venv\Scripts\python.exe -m ruff format .
& .\.venv\Scripts\python.exe manage.py check --settings=app.settings_dev