# The short version

An inventory manager blueprint for independent retailers built with Django on Ample. Domain schema: products (sku, name, category, price, active): the SKU catalog; stock_movements (sku, location, delta, reason, moved_at): receipts, sales and adjustments; orders (order_no, customer_reference, status, placed_at): orders with status transitions; order_lines (order_no, sku, qty, unit_price): order contents; events (seq, record_type, record_id, kind, at): application-owned history written in the same transaction. Public information: product catalog and availability, store locations and hours, returns policy. Kept out of scope until handling is reviewed: customer contact and payment details, supplier cost prices. Payment details belong to your payment provider; only order status and public catalog data are modeled here. 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).

# INFRASTRUCTURE

## What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [Postgres](/content/discover/primitive/postgres/index.html): verified (Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.)
- [S3-compatible object storage](/content/discover/primitive/s3-compatible-object-storage/index.html): verified (Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.)

# PREREQUISITES

## Before you start

- 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 independent retailers data classes may be handled at all; this blueprint models public information only

# STEP BY STEP

## How to do it

1. **Model the independent retailers domain**  
   Create the tables products, stock_movements, orders, order_lines, events. The sku catalog lives in products; keep the sensitive classes (customer contact and payment details, supplier cost prices) 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.
   
   ```  
   ample deploy . --name <app-name> --public --start "python3 run.py" --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...
   ```

7. **Verify**  
   Run the pattern self-test(s) from the example (/p/transactional-workflows) and your own acceptance checks for the independent retailers workflow.
   
   ```
   ample logs <deployment_id> --kind build
   ```

# EXAMPLES

## Tested examples

- **Django pattern fixture** (`tests/deploy-canaries/django-patterns`): Verified transactional workflows basis for this blueprint.

# SUCCESS CHECKS

## How to know it worked

- app responds on its public URL (`/` on the live URL, expect ample canary django patterns)
- transactional-workflows self-test from the example (`/p/transactional-workflows` on the live URL, expect see the pattern fixture checks)

# COST

## Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision ca0b484a7a9957c573a88d3a32dc603c3c10135a).
- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Upper-bound monthly price of the tested sizes. Buckets are allocation-priced per quota and not included.

# EVIDENCE

## Verification evidence

- canary_run on 2026-09-20T03:31:44Z at revision `03b6402b1b3e19178985f08ea4033804521d85d4 (CLI b75e104)`: Django pattern fixture deployed on Ample (pip install into .ample/python from requirements.txt, then waitress serving project.wsgi from run.py reading PORT on the python-3.12 template); the transactional workflows checks passed: 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). The blueprint's Independent retailers schema and workflow below build on that verified basis and were not separately executed. (expires 2027-03-19T03:31:44Z)

# EXECUTION

## Execution binding

MCP tool `ample_deploy` (registry `mcp:ample_deploy`), schema hash `876465fce906da0c` observed 2026-09-22T00:31:22.774679+00:00 at revision `e6446ceea69b`. Binding state at export: schema_changed. Required scopes: servers:write, databases:read, buckets:read.

# NEXT ACTIONS

## Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse Independent retailers (`GET /v1/catalog/nodes/industry%3Aindependent-retailers` on the api origin; authentication not required, approval not required)
- Browse Inventory manager (`GET /v1/catalog/nodes/workload%3Ainventory-manager` on the api origin; authentication not required, approval not required)
- Browse Django (`GET /v1/catalog/nodes/stack%3Aframework-django` on the api origin; authentication not required, approval not required)
- Browse Deploy web app (`GET /v1/catalog/nodes/intent%3Adeploy-web-app` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

# ABOUT THIS RECIPE

## Identifiers and status

Recipe `page:blueprints:independent-retailers:inventory-manager:django`. Revision r1.

release **published** support **verified** execution **blocked (schema_changed: live tool schema differs from the recorded binding)**

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