# Equipment rental: Inventory manager using Django

## Summary
A inventory manager blueprint for equipment rental built with Django on Ample.

### Domain schema:
- **equipment** (sku, name, category, day_rate, serial_tracked): rental catalog;
- **stock_movements** (sku, unit_serial, delta, reason, moved_at): check-outs, returns and maintenance;
- **rentals** (rental_no, period_start, period_end, status): rentals with status transitions;
- **rental_lines** (rental_no, sku, unit_serial, rate): rental contents;
- **events** (seq, record_type, record_id, kind, at): application-owned history written in the same transaction.

Public information: equipment catalog and rates, availability calendar, deposit and insurance terms. Kept out of scope until handling is reviewed: renter identity documents, payment and deposit details. Identity verification and deposits are outside these flows; only availability and rental status are modeled.

Technical basis verified on Django: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected).

## Prerequisites
- A Django project (pip install into .ample/python from requirements.txt, then waitress serving project.wsgi from run.py reading PORT on the python-3.12 template)
- A PostgreSQL driver reading DATABASE_URL (auto-provisioned when omitted)
- Bucket credentials from `ample bucket create` passed as encrypted S3_* environment variables
- A review of which equipment rental data classes may be handled at all; this blueprint models public information only

## Framework and Resource Requirements
- **Framework**: Django
- **Workload**: Inventory manager
- **Industry**: Equipment rental
- **Resource Requirements**: 
  - **primitive:compute** 
  - **primitive:postgres** 
  - **primitive:s3-compatible-object-storage**

## Workflow Steps
1. **Model the equipment rental domain**: Create the tables equipment, stock_movements, rentals, rental_lines, events. Rental catalog lives in equipment; keep the sensitive classes (renter identity documents, payment and deposit details) out of this schema.
2. **Workflow step 1**: Model SKUs and stock movements; derive stock from movements  
3. **Workflow step 2**: Apply movements transactionally with an optimistic version check on the SKU  
4. **Workflow step 3**: Record an event per movement for history  
5. **Workflow step 4**: Deploy and verify history and rejected stale updates  
6. **Deploy**: Run the synchronous deploy once and read the result. Re-running with no change is a no-op.

## Examples
- **Title**: Django pattern fixture  
  **Description**: Verified transactional workflows basis for this blueprint.  
  **Source Ref**: tests/deploy-canaries/django-patterns

## Success Checks
- **app responds on its public URL**  
  **kind**: http_get  
  **path**: /  
  **expect**: ample canary django patterns  
- **transactional-workflows self-test from the example**  
  **kind**: http_get  
  **path**: /p/transactional-workflows  
  **expect**: see the pattern fixture checks

## Limitations
- The technical basis (transactional workflows on Django) was verified with the pattern fixture; the equipment rental schema and workflow are an original design for this blueprint and were not executed as a separate application.
- No health, financial, privacy or other compliance claim is made. Identity verification and deposits are outside these flows; only availability and rental status are modeled.
- Verified on the python-3.12 template at s-1vcpu-1gb; region, request-duration limits and other sizes are unknown or unverified.

## Cost Estimate
- **Currency**: USD  
- **Monthly Amount**: 10.0  
- **Basis**: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty  
- **Components**:  
  - **app server**: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0  
  - **managed PostgreSQL database**: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0

**Note**: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.