Reverse Engineering Your Software program Structure with Claude Code to Assist Claude Code – O’Reilly

I’ve been utilizing Claude Code for a wide range of functions, and one factor I’ve realized is that the extra it understands concerning the performance of the system (the area, the use instances, the end-to-end flows), the extra it might assist me.

For instance, after I paste a manufacturing error log, Claude can learn the stack hint, determine the affected code, and inform me if there’s a bug. However when the problem is extra advanced, like a buyer help ticket, and there’s no stack hint, Claude is much less helpful.

The primary problem is that end-to-end processes are lengthy and complicated, spanning many code repositories. So simply asking Claude Code to research a single repository wasn’t going to work (and the default /init wasn’t producing ample element even for this single codebase).

So I made a decision to make use of Claude Code to research the system to map out the end-to-end flows related to the area I work in in order that Claude Code (and people) can use this to deal with extra advanced challenges.

This publish shares what I knocked collectively in in the future, constructing on information and tooling I’ve already gained from actual work examples and experiments.

That is one publish in a collection. You’ll find the opposite posts right here.

This publish was written 100% by me. I requested Claude to generate the anonymized instance on the finish mirroring the kind of content material and elegance utilized in the true examples I created.

Setting the Preliminary Context

To start my challenge, I created a really gentle necessities doc:

# AI Structure Evaluation

This doc accommodates the directions for an essential job - utilizing AI to outline the structure of this technique, in order that it may be utilized by people and AI brokers to extra simply perceive the system.

## Goal

Map out the entire flows that this software is concerned in (use sub brokers the place essential to work in parallel). A stream ought to map out the end-to-process from an motion within the UI (within the [readacted] repo) to a BFF, to backend APIs, or flows which are triggered by occasions.

Flows needs to be documented in Mermaid format to permit AI brokers to grasp, for versioning (in git), and for simple visualization.

## Necessities

Every stream ought to have a descriptive title and may embody:

1. The URL path of the web page the place the interplay is triggered
2. The URL path of the BFF endpoint (and the repository it lives in)
3. The URL path of calls made to downstream companies
4. Any database interactions
5. Any occasions produced or consumed (full title of occasion e.g. orders.orderPlaced)
6. Shoppers of occasions (if straightforward to determine)
7. Any workflows triggered (just like the synchronizeOrder)

To do that, you have to to look in different repositories, which could be discovered within the mum or dad folder. The GitHub shopper will also be used if obligatory.

The listing of flows ought to reside in ../flows/index.md and every particular person stream needs to be outlined in a separate folder.

# The place to search out info

- /docs/structure accommodates numerous folders describing the design of this technique and area information
- Every API challenge on this repository ([redacted], [redacted]) has an openapi.json. This should be used to determine all flows and validate. The [redacted] and [redacted] repositories even have openapi spec information
- The entities within the area [redacted], [redacted] [redacted] have technique that clearly describe the area operations that may be carried out on them. Equally, every operation is invoke from a use case that clearly describes the use case

The output I need is end-to-end flows like:
UI -> BFF -> API -> replace DB -> publish occasion -> handler -> use case -> publish occasion -> …

I don’t need 10 completely different sorts of structure diagrams and completely different ranges of element. I need Claude Code to grasp the habits of the system so it might determine anomalies (by taking a look at manufacturing knowledge and logs) and analyze the affect of potential modifications.

I additionally created some gentle details about the system in these two information:

The area ideas file explains the entities within the system. Very transient clarification. The system overview file explains the connection between this codebase and different repositories, which is essential. Once more, it’s very gentle—a bullet listing of repository names and one or two sentences describing their relationship to this one.

Looking out throughout a number of repositories

The directions for this job reside inside the primary repository of the area I work in. That is the middle of the universe for this agent, but it surely wants to have the ability to learn different repositories to affix up the end-to-end stream.

The answer I take advantage of for that is within the description above:

To do that, you have to to look in different repositories which could be discovered within the mum or dad folder. The GitHub shopper will also be used if obligatory.

I give Claude the next permissions in .claude/settings.native.json and it might then entry all of the repositories on machine or use the GitHub shopper if it thinks there are repositories I don’t have obtainable regionally:

"permissions": {
   "permit": [
     ...
     "Read(//Users/nicktune/code/**)",
     ...

Telling Claude where to look

You’ll notice the requirements also give Claude tips on where to look for key information like Open API spec files, which are like an index of the operations the application supports.

This is useful as a validation mechanism later in the flow. I would ask Claude, “List all of the API endpoints and events produced or consumed by this application—are there any that aren’t part of any flows.” I can then see if we may have missed anything important.

Mapping the First Flow

I put Claude in plan mode and asked it to read the file. It then popped up a short questionnaire asking me about my needs and preferences. One of the questions it asked was process related: Should we map out the whole system in parallel, work step-by-step, etc.?

I said, let’s do the first one together and use this as a template for the others to follow.

It took about two hours to build the first flow as I reviewed what Claude produced and gave feedback on what I needed. For example, at first it created a sequence diagram which looked nice but was too hard to read for complex flows that involve many repositories.

Eventually, we settled on horizontal flow diagrams where each repository is a container and we defined what steps could be. At first, it went too granular with the steps adding individual method calls.

### diagram.mermaid Requirements
**CRITICAL RULES:**
1. **File Format**: Must be pure Mermaid syntax with `.mermaid` extension- NO markdown headers
 - NO markdown code fences (no ` ```mermaid ` wrapper)
 - Starts directly with `flowchart LR`
2. **Use Swimlane Format**: `flowchart LR` (left-to-right with horizontal swimlanes)
 - Each repository is a horizontal swimlane (subgraph)
 - Flow progresses left to right
 - Swimlane labels should be prominent (use emoji for visibility)
 - Example: `subgraph systemA["🔧 systemA"]`
3. **Techniques as Containers**:
 - Every repository MUST be a `subgraph` (horizontal swimlane)
 - Repository title is the subgraph label
 - Operations are nodes contained in the subgraph
 - Use `path LR` inside every subgraph
4. **Legitimate Step Varieties** - A step within the diagram can ONLY be one of many following:
 - **HTTP Endpoint**: Full endpoint path (e.g., `POST /blah/{blahId}/subblah`)
 - **Mixture Methodology Name**: Area technique on an combination (e.g., `Order.place`, `Delivery.organiz`)
 - **Database Operation**: Proven with cylinder form `[(Database: INSERT order)]`
 - **Occasion Publication**: (e.g., `Publish: personal.ordering.order.positioned`)
 - **Workflow Set off**: Have to be labeled as workflow (e.g., `⚙️ Workflow: syncOrders`)
 - **Workflow Step**: Any step inside a workflow MUST embody the workflow title as prefix (e.g., `syncOrderWorkflow: Replace legacy order`, `updateOrderInfo: POST /legacy/fill-order`)
 - **Lambda Invocation**: (e.g., `Lambda: blah-blah-lambda-blah-blah`)
 - **UI Actions**: Person interactions (e.g., `Present modal kind`, `Person enters firstName, lastName`)

I’ve added an anonymized stream on the finish of this doc.

I additionally had so as to add some corrections to Claude to make sure it was wanting in all the fitting locations and understanding what sure ideas imply in different components of our system; we weren’t simply iterating on the diagram for 2 hours.

Selecting the Subsequent Stream

After the primary stream, the subsequent flows went a lot sooner. I verified the output of every stream and gave Claude suggestions, however usually round quarter-hour, and more often than not it was working so I may do different issues whereas ready.

One of many fascinating challenges was deciding which flows are literally wanted? What’s a stream? The place ought to a stream begin and finish? What about relationships between flows?

Right here I used to be within the driving seat fairly a bit. I requested Claude to suggest flows (simply listing them earlier than analyzing) after which I requested it to point out me how every API endpoint and occasion match into the flows, and we used that to iterate a bit.

One of many issues I needed to do after Claude had produced the primary draft is to ask, “Are you positive there are not any different shoppers for these occasions that aren’t listed right here?” It could then do a extra thorough search and generally discover shoppers in repositories I didn’t have regionally. (It could use GitHub search.)

Studying worth

As I reviewed every use case, I used to be studying issues concerning the system that I didn’t totally perceive or possibly there have been nuances I wasn’t conscious of. This alone would have justified all the trouble I spent on this.

Then I began to think about the worth for people who find themselves new to a codebase or a legacy system that no one understands anymore. Or possibly somebody who works in a unique workforce and wishes to determine how a bug or a change of their area is expounded to different domains.

Evolving the Necessities

As we went via the method, I often instructed Claude to replace the necessities file. So after we’d completed the primary stream we had directions like this added to the file:

## Documentation Construction

Every stream should be documented in a separate folder with the next construction:

```
docs/structure/flows/[flow-name]/
├── README.md              # Full documentation (all content material in a single file)
└── diagram.mermaid        # Mermaid diagram
```

**IMPORTANT**: Use ONLY these two information. Do NOT create separate diagram-notes.md or different information. Maintain all documentation consolidated in README.md for simpler upkeep.

### README.md Contents

**Use the blueprint as a template**: `docs/structure/flows/[redacted]/`

The file is now 449 traces lengthy.

One of many causes I did this was in order that I may begin a brand new Claude session, now or sooner or later, with out a utterly clear context window and execute the method to get related outcomes.

I did truly use a brand new session to map every new stream to validate that the necessities had been considerably repeatable. Usually they had been, however usually Claude would ignore some components of the necessities. So on the finish, I instructed it to evaluation the necessities and examine the outputs, and it might normally determine a lot of the errors it had made and repair them.

Right here’s an instance of among the guidelines that began to construct up. Some had been to make sure Claude produced the fitting sort of output, and a few had been to assist Claude keep away from frequent errors like Mermaid syntax errors.

### 2. Hint Workflows to Their Last Occasion
**Drawback**: Lacking occasions since you do not learn the precise workflow implementation.
**Rule**: While you encounter a workflow, you MUST:
1. Discover the workflow definition file (normally `.asl.json` for AWS Step Features)
2. Learn the ENTIRE workflow to see ALL occasions it publishes
3. Doc EVERY occasion in sequence
**Instance from our blueprint**:
- We initially thought `[readacted]` ended with `[readacted]`
- Studying `[redacted].asl.json` revealed it truly ends with `[readacted]`
- This occasion was CRITICAL to the stream persevering with
**File areas**:
- Integrations workflows: `[another-repo]/domains/*/workflows/*.asl.json`
- Search for `SendEvent` or `publish` actions within the workflow steps

Claude Code by no means follows each instruction as described. However including these guidelines does appear to extend the standard and scale back the variety of iterations wanted.

Testing the Output

After I mapped out 4 or 5 of the flows, I made a decision it was time to try it out—Does this info truly assist Claude Code, or is it primarily only a human viewers that advantages from the outputs?

So I went into our help ticket system and picked a ticket that appeared advanced. I requested my investigation agent to have a look at the ticket and determine the issue. However this time I added an additional step into its directions:

4. Establish the affected flows in /docs/structure/flows

As a part of its evaluation, it mentioned:

Let me discover the structure flows to grasp how [redacted] and [redacted] needs to be dealt with:

Then it produced its evaluation accurately figuring out the stream and anticipated behaviors:

## Affected Stream

**[BlahA Upload and BlahB History Thing](../structure/flows/[redacted]/README.md)**

The [redacted] workflow ought to populate [redacted] knowledge through:
- [redacted] choice ([redacted] normal OR [redacted] enhanced primarily based on `[redacted]` flag)
- Parallel execution of: DomainA, DomainB, DomainC, DomainD
- Publishing `order.blahBlahed` occasion on completion
…

And for the subsequent steps, it needed to question the occasions revealed by the system to confirm that what truly occurred matched the anticipated behaviors outlined within the stream:

### Step 1: Question [redacted] Occasions for Each [redacted]
**Goal:** Examine occasion historical past to determine what occurred otherwise between outdated and new [redacted]
**What to search for:**
- `[redacted event name]` - Did [redacted] full for brand spanking new [redacted]?
- `[redacted event name]` - Had been [redacted] created?
- `[redacted event name]` - Had been [redacted] created?
- `[redacted event name]` - Did workflow full for brand spanking new [redacted]?
- `[redacted event name]` - Last affirmation occasion
- Any error/failure occasions associated to the workflow

Beforehand, Claude would have needed to analyze the codebase to work out what ought to have occurred. It takes a very long time and takes up loads of context window for advanced duties, and the evaluation must be verified.

Now, Claude is aware of instantly concerning the particular workflow and affected behaviors and might instantly start planning an investigation (if the documentation is correct sufficient). This evaluation is structured with the important thing info that I must see. I don’t must iterate with Claude to provide an evaluation within the format I would like.

On this case, Claude didn’t resolve the issue instantly, however the dialog was extra like I may need with a workforce member—somebody who has a deeper understanding of how the system works and what could be fallacious right here moderately than simply utilizing Claude to research patterns in knowledge, learn stack traces, or summarize textual content descriptions of the issue.

Accuracy and Hallucinations

I do suppose it’s proper to be involved about accuracy. We don’t need to make essential decisions about our system primarily based on incomplete or incorrect particulars. And there have been important inaccuracies that I needed to spot and proper. (Think about if I didn’t know they had been fallacious.)

I explored the problem of accuracy in this later publishdisplaying how we will use deterministic instruments like ts-morph to construct the mannequin that people and AI can each profit from.

So right here’s what I’m pondering:

1. Typically we don’t want excellent accuracy. So long as the agent picks the fitting path, it might reinspect sure particulars or dive deeper as wanted.
2. We will construct checks and steps in into our CI pipelines to replace issues.
3. Repeatedly destroy and regenerate the flows (as soon as 1 / 4?).
4. Construct verification brokers or swarms.

Once I noticed an error and requested a brand new agent to research the stream for inaccuracies, it rescanned the code and located what I noticed. So I believe choice 4 may be very credible—it’s simply extra effort to construct a verification system (which may make the general effort not value it).

However I’m undecided that is the optimum means of approaching the state of affairs. As an alternative…

The Subsequent Section of Platform Engineering

Avoiding the necessity to reverse engineer these flows can be key. And I’m beginning to suppose this can develop into the primary problem for platform engineering groups: How can we construct frameworks and tooling that expose our system as a graph of dependencies? Constructed into our platform in order that AI brokers don’t must reverse engineer; they will simply seek the advice of the supply of reality.

Issues ought to all occur transparently for software program engineers—you observe the platform paved path, and all the pieces simply works. Corporations that do that, and particularly startups with no legacy, may immensely revenue from AI brokers.

Instruments like EventCatalog are in a powerful place right here.

Instance Stream

I simply requested Claude to translate one in all my firm’s area flows right into a boring ecommerce instance. The design and naming shouldn’t be essential; the kind of info and the visualization is what I’m attempting to convey.

Bear in mind, that is primarily based on in the future of hacking round. I’m positive there are many enchancment alternatives right here. Let me know if in case you have seen something higher.

The README

# Place Order with Fee and Success

**Standing**: Energetic
**Kind**: Write Operation
**Complexity**: Excessive
**Final Up to date**: 2025-10-19

## Overview

This stream paperwork the method of putting an order in an ecommerce system, together with cost authorization, stock reservation, and cargo creation. That is the baseline order placement expertise the place:
- Orders begin with `standing: 'pending'`
- Fee is permitted earlier than stock reservation
- Stock is reserved upon profitable cost
- Cargo is created after stock reservation

## Stream Boundaries

**Begin**: Buyer clicks "Place Order" button on checkout web page

**Finish**: Publication of `transport.shipment-created` occasion (public occasion with `DOMAIN` scope)

**Scope**: This stream covers your entire course of from preliminary order submission via cost authorization, stock reservation, cargo creation, and all asynchronous unintended effects triggered by these operations.

## Fast Reference

### API Endpoints

| Endpoint | Methodology | Repository | Objective |
|----------|--------|------------|---------|
| `/checkout` | GET | storefront-app | Checkout web page |
| `/api/orders` | POST | order-api | Creates order |
| `/api/funds/authorize` | POST | payment-api | Authorizes cost |
| `/api/stock/reserve` | POST | inventory-api | Reserves stock |
| `/api/shipments` | POST | shipping-api | Creates cargo |
| `/api/orders/{orderId}/standing` | GET | order-api | Frontend polls for order standing |

### Occasions Reference

| Occasion Identify | Area | Topic | Objective | Shoppers |
|------------|--------|---------|---------|-----------|
| `personal.orders.order.created` | ORDERS | order | Order creation | PaymentHandler, AnalyticsHandler |
| `personal.funds.cost.licensed` | PAYMENTS | cost | Fee licensed | InventoryReservationHandler |
| `personal.funds.cost.failed` | PAYMENTS | cost | Fee failed | OrderCancellationHandler |
| `personal.stock.inventory.reserved` | INVENTORY | inventory | Stock reserved | ShipmentCreationHandler |
| `personal.stock.inventory.inadequate` | INVENTORY | inventory | Inadequate inventory | OrderCancellationHandler |
| `personal.transport.cargo.created` | SHIPPING | cargo | Cargo created | NotificationHandler |
| `transport.shipment-created` | SHIPPING | cargo | **PUBLIC** Cargo created | Exterior shoppers |

### Database Tables

| Desk | Operation | Key Fields | Objective |
|-------|-----------|------------|---------|
| `orders` | INSERT | orderId, customerId, standing="pending", totalAmount | Order combination storage |
| `order_items` | INSERT | orderItemId, orderId, productId, amount, worth | Order line objects |
| `funds` | INSERT | paymentId, orderId, quantity, standing="licensed" | Fee combination storage |
| `inventory_reservations` | INSERT | reservationId, orderId, productId, amount | Stock reservation monitoring |
| `shipments` | INSERT | shipmentId, orderId, trackingNumber, standing="pending" | Cargo combination storage |

### Area Operations

| Mixture | Methodology | Objective |
|-----------|--------|---------|
| Order | `Order.create()` | Creates new order with pending standing |
| Order | `Order.confirmPayment()` | Marks cost as confirmed |
| Order | `Order.cancel()` | Cancels order attributable to cost or stock failure |
| Fee | `Fee.authorize()` | Authorizes cost for order |
| Fee | `Fee.seize()` | Captures licensed cost |
| Stock | `Stock.reserve()` | Reserves inventory for order |
| Cargo | `Cargo.create()` | Creates cargo for order |

## Key Traits

| Side | Worth |
|--------|-------|
| Order Standing | Makes use of `standing` area: `'pending'` → `'confirmed'` → `'shipped'` |
| Fee Standing | Makes use of `standing` area: `'pending'` → `'licensed'` → `'captured'` |
| Stock Technique | Reserve-on-payment method |
| Cargo Standing | Makes use of `standing` area: `'pending'` → `'prepared'` → `'shipped'` |

## Stream Steps

1. **Buyer** navigates to checkout web page in storefront-app (`/checkout`)
2. **Buyer** evaluations order particulars and clicks "Place Order" button
3. **storefront-app UI** reveals loading state with order affirmation message
4. **storefront-app** sends POST request to order-api (`/api/orders`)
  - Request consists of: customerId, objects (productId, amount, worth), shippingAddress, billingAddress
5. **order-api** creates Order combination with `standing: 'pending'` and persists to database
6. **order-api** creates OrderItem data for every merchandise within the order
7. **order-api** publishes `personal.orders.order.created` occasion
8. **order-api** returns orderId and order particulars to storefront-app
9. **storefront-app** redirects buyer to order affirmation web page

### Asynchronous Facet Results - Fee Processing

10. **order-events-consumer** receives `personal.orders.order.created` occasion
11. **PaymentHandler** processes the occasion
   - Calls payment-api to authorize cost
12. **payment-api** calls exterior cost gateway (Stripe, PayPal, and so on.)
13. **payment-api** creates Fee combination with `standing: 'licensed'` and persists to database
14. **payment-api** publishes `personal.funds.cost.licensed` occasion (on success)
   - OR publishes `personal.funds.cost.failed` occasion (on failure)

### Asynchronous Facet Results - Stock Reservation

15. **payment-events-consumer** receives `personal.funds.cost.licensed` occasion
16. **InventoryReservationHandler** processes the occasion
   - Calls inventory-api to order inventory
17. **inventory-api** hundreds Stock combination for every product
18. **inventory-api** calls `Stock.reserve()` for every order merchandise
   - Validates ample inventory obtainable
   - Creates reservation file
   - Decrements obtainable inventory
19. **inventory-api** creates InventoryReservation data and persists to database
20. **inventory-api** publishes `personal.stock.inventory.reserved` occasion (on success)
   - OR publishes `personal.stock.inventory.inadequate` occasion (on failure)

### Asynchronous Facet Results - Cargo Creation

21. **inventory-events-consumer** receives `personal.stock.inventory.reserved` occasion
22. **ShipmentCreationHandler** processes the occasion
   - Calls shipping-api to create cargo
23. **shipping-api** creates Cargo combination with `standing: 'pending'` and persists to database
24. **shipping-api** calls exterior transport provider API to generate monitoring quantity
25. **shipping-api** updates Cargo with trackingNumber
26. **shipping-api** publishes `personal.transport.cargo.created` occasion
27. **shipping-events-consumer** receives `personal.transport.cargo.created` occasion
   - **ShipmentCreatedPublicHandler** processes the occasion
   - Masses cargo from repository to get full cargo particulars
   - Publishes public occasion: `transport.shipment-created`
   - **This marks the END of the stream**

### Order Standing Updates

28. All through the stream, order-api receives occasions and updates order standing:
   - On `personal.funds.cost.licensed`: Updates order with paymentId
   - On `personal.stock.inventory.reserved`: Updates order to `standing: 'confirmed'`
   - On `personal.transport.cargo.created`: Updates order to `standing: 'shipped'`

### Failure Eventualities

**Fee Failure**:
- On `personal.funds.cost.failed`: OrderCancellationHandler cancels order
- Order standing up to date to `'cancelled'`
- Buyer notified through e-mail

**Stock Failure**:
- On `personal.stock.inventory.inadequate`: OrderCancellationHandler cancels order
- Fee authorization is voided
- Order standing up to date to `'cancelled'`
- Buyer notified through e-mail with choice to backorder

## Repositories Concerned

- **storefront-app**: Frontend UI
- **order-api**: Order area
- **payment-api**: Fee area
- **inventory-api**: Stock area
- **shipping-api**: Delivery and success area
- **notification-api**: Buyer notifications

## Associated Flows

- **Course of Refund**: Stream for dealing with order refunds and returns
- **Replace Cargo Standing**: Stream for monitoring cargo supply standing
- **Stock Reconciliation**: Stream for syncing stock counts with warehouse methods

## Occasions Produced

| Occasion | Objective |
|-------|---------|
| `personal.orders.order.created` | Notifies {that a} new order has been created |
| `personal.funds.cost.licensed` | Notifies that cost has been licensed |
| `personal.funds.cost.failed` | Notifies that cost authorization failed |
| `personal.stock.inventory.reserved` | Notifies that stock has been reserved |
| `personal.stock.inventory.inadequate` | Notifies that inadequate stock is out there |
| `personal.transport.cargo.created` | Inside occasion that cargo has been created |
| `transport.shipment-created` | **Public occasion** that cargo is created and prepared for provider pickup |

## Occasion Shoppers

### `personal.orders.order.created` Shoppers

#### 1. order-events-consumer

**Handler**: `PaymentHandler`

**Objective**: Initiates cost authorization course of

**Actions**:
- Subscribes to occasion
- Calls `AuthorizePayment` use case
- Invokes payment-api to authorize cost with cost gateway
- Publishes cost end result occasion

#### 2. order-events-consumer

**Handler**: `AnalyticsHandler`

**Objective**: Tracks order creation for analytics

**Actions**:
- Subscribes to occasion
- Sends order knowledge to analytics platform
- Updates conversion monitoring

### `personal.funds.cost.licensed` Client

#### payment-events-consumer

**Handler**: `InventoryReservationHandler`

**Objective**: Reserves stock after profitable cost

**Actions**:
- Subscribes to occasion
- Calls `ReserveInventory` use case
- Masses order particulars
- Calls inventory-api to order inventory for every merchandise
- Publishes stock reservation end result occasion

### `personal.funds.cost.failed` Client

#### payment-events-consumer

**Handler**: `OrderCancellationHandler`

**Objective**: Cancels order when cost fails

**Actions**:
- Subscribes to occasion
- Calls `CancelOrder` use case
- Updates order standing to 'cancelled'
- Triggers buyer notification

### `personal.stock.inventory.reserved` Client

#### inventory-events-consumer

**Handler**: `ShipmentCreationHandler`

**Objective**: Creates cargo after stock reservation

**Actions**:
- Subscribes to occasion
- Calls `CreateShipment` use case
- Calls shipping-api to create cargo file
- Integrates with transport provider API for monitoring quantity
- Publishes cargo created occasion

### `personal.stock.inventory.inadequate` Client

#### inventory-events-consumer

**Handler**: `OrderCancellationHandler`

**Objective**: Cancels order when stock is inadequate

**Actions**:
- Subscribes to occasion
- Calls `CancelOrder` use case
- Voids cost authorization
- Updates order standing to 'cancelled'
- Triggers buyer notification with backorder choice

### `personal.transport.cargo.created` Client

#### shipping-events-consumer

**Handler**: `ShipmentCreatedPublicHandler`

**Objective**: Converts personal cargo occasion to public occasion

**Actions**:
- Subscribes to `personal.transport.cargo.created` occasion
- Masses cargo from repository
- Publishes public occasion: `transport.shipment-created`

**Handler**: `NotificationHandler`

**Objective**: Notifies buyer of cargo creation

**Actions**:
- Subscribes to occasion
- Sends affirmation e-mail with monitoring quantity
- Sends SMS notification (if opted in)

## Database Operations

### orders Desk
- **Operation**: INSERT (through upsert)
- **Key Fields**: orderId, customerId, standing="pending", totalAmount, createdAt
- **Repository**: `OrderRepository`

### order_items Desk
- **Operation**: INSERT (batch)
- **Key Fields**: orderItemId, orderId, productId, amount, worth
- **Repository**: `OrderItemRepository`

### funds Desk
- **Operation**: INSERT (through upsert)
- **Key Fields**: paymentId, orderId, quantity, standing="licensed", gatewayTransactionId
- **Repository**: `PaymentRepository`

### inventory_reservations Desk
- **Operation**: INSERT (through upsert)
- **Key Fields**: reservationId, orderId, productId, amount, reservedAt
- **Repository**: `InventoryReservationRepository`

### shipments Desk
- **Operation**: INSERT (through upsert)
- **Key Fields**: shipmentId, orderId, trackingNumber, standing="pending", provider
- **Repository**: `ShipmentRepository`

## Exterior Integrations

- **Fee Gateway Integration**: Authorizes and captures funds through Stripe API
 - Endpoint: `/v1/payment_intents`
 - Synchronous name throughout cost authorization

- **Delivery Service Integration**: Generates monitoring numbers through provider API
 - Endpoint: `/api/v1/shipments`
 - Synchronous name throughout cargo creation

## What Occurs After This Stream

This stream ends with the publication of the `transport.shipment-created` public occasion, which marks the order as totally processed and prepared for provider pickup.

### State at Stream Completion
- Order: `standing: 'shipped'`
- Fee: `standing: 'licensed'` (can be captured on precise cargo)
- Stock: Inventory reserved and decremented
- Cargo: `standing: 'pending'`, trackingNumber assigned

### Subsequent Steps
After this stream completes:
- Warehouse workforce picks and packs the order
- Service picks up the cargo
- Delivery standing updates stream tracks supply
- Fee is captured upon confirmed cargo
- Buyer can monitor order through monitoring quantity

### Exterior System Integration
As soon as the `transport.shipment-created` occasion is revealed:
- Warehouse administration system begins decide/pack course of
- Buyer notification system sends monitoring updates
- Logistics companions obtain cargo manifest
- Analytics methods monitor success metrics

## Diagram

See [diagram.mermaid](./diagram.mermaid) for the entire visible stream displaying the development via methods with horizontal swim lanes for every service.

The Mermaid:

flowchart LR
   Begin([Customer clicks Place Order
on checkout page])

   subgraph storefront["🌐 storefront-app"]
       path LR
       ShowCheckout[Show checkout page]
       CustomerReview[Customer reviews order]
       ShowConfirmation[Show order
confirmation page]
   finish

 CustomerWaitsForShipment([Customer receives
shipment notification])

subgraph orderService["📦 order-api"]
       path LR
       CreateOrderEndpoint["POST /api/orders"]
       OrderCreate[Order.create]
       OrderDB[(Database:
INSERT orders,
order_items)]
       PublishOrderCreated["Publish: private.orders
.order.created"]
       ReceivePaymentAuth["Receive: private.payments
.payment.authorized"]
       UpdateOrderPayment[Update order
with paymentId]
       ReceiveStockReserved["Receive: private.inventory
.stock.reserved"]
       OrderConfirm[Order.confirmPayment]
       UpdateOrderConfirmed[(Database:
UPDATE orders
status="confirmed")]
       ReceiveShipmentCreated["Receive: private.shipping
.shipment.created"]
       UpdateOrderShipped[(Database:
UPDATE orders
status="shipped")]
   finish

 subgraph paymentService["💳 payment-api"]
       path LR
       ReceiveOrderCreated["Receive: private.orders
.order.created"]
       AuthorizeEndpoint["POST /api/payments/
authorize"]
       PaymentGateway["External: Payment
Gateway API
(Stripe)"]
       PaymentAuthorize[Payment.authorize]
       PaymentDB[(Database:
INSERT payments)]
       PublishPaymentAuth["Publish: private.payments
.payment.authorized"]
   finish

 subgraph inventoryService["📊 inventory-api"]
       path LR
       ReceivePaymentAuth2["Receive: private.payments
.payment.authorized"]
       ReserveEndpoint["POST /api/inventory/
reserve"]
       InventoryReserve[Inventory.reserve]
       InventoryDB[(Database:
INSERT inventory_reservations
UPDATE product stock)]
       PublishStockReserved["Publish: private.inventory
.stock.reserved"]
   finish

 subgraph shippingService["🚚 shipping-api"]
       path LR
       ReceiveStockReserved2["Receive: private.inventory
.stock.reserved"]
       CreateShipmentEndpoint["POST /api/shipments"]
       CarrierAPI["External: Shipping
Carrier API
(FedEx/UPS)"]
       ShipmentCreate[Shipment.create]
       ShipmentDB[(Database:
INSERT shipments)]
       PublishShipmentCreated["Publish: private.shipping
.shipment.created"]
       ReceiveShipmentCreatedPrivate["Receive: private.shipping
.shipment.created"]
       LoadShipment[Load shipment
from repository]
       PublishPublicEvent["Publish: shipping
.shipment-created"]
       FlowEnd([Flow End:
Public event published])
   finish

   Begin --> ShowCheckout
   ShowCheckout --> CustomerReview
   CustomerReview --> CreateOrderEndpoint
   CreateOrderEndpoint --> OrderCreate
   OrderCreate --> OrderDB
   OrderDB --> PublishOrderCreated
   PublishOrderCreated --> ShowConfirmation

   PublishOrderCreated -.-> ReceiveOrderCreated
   ReceiveOrderCreated --> AuthorizeEndpoint
   AuthorizeEndpoint --> PaymentGateway
   PaymentGateway --> PaymentAuthorize
   PaymentAuthorize --> PaymentDB
   PaymentDB --> PublishPaymentAuth

   PublishPaymentAuth -.-> ReceivePaymentAuth
   ReceivePaymentAuth --> UpdateOrderPayment

   PublishPaymentAuth -.-> ReceivePaymentAuth2
   ReceivePaymentAuth2 --> ReserveEndpoint
   ReserveEndpoint --> InventoryReserve
   InventoryReserve --> InventoryDB
   InventoryDB --> PublishStockReserved

   PublishStockReserved -.-> ReceiveStockReserved
   ReceiveStockReserved --> OrderConfirm
   OrderConfirm --> UpdateOrderConfirmed

   PublishStockReserved -.-> ReceiveStockReserved2
   ReceiveStockReserved2 --> CreateShipmentEndpoint
   CreateShipmentEndpoint --> CarrierAPI
   CarrierAPI --> ShipmentCreate
   ShipmentCreate --> ShipmentDB
   ShipmentDB --> PublishShipmentCreated

   PublishShipmentCreated -.-> ReceiveShipmentCreated
   ReceiveShipmentCreated --> UpdateOrderShipped

   PublishShipmentCreated -.-> ReceiveShipmentCreatedPrivate
   ReceiveShipmentCreatedPrivate --> LoadShipment
   LoadShipment --> PublishPublicEvent
   PublishPublicEvent --> FlowEnd

   FlowEnd -.-> CustomerWaitsForShipment

   type Begin fill:#e1f5e1
   type FlowEnd fill:#ffe1e1
   type CustomerWaitsForShipment fill:#e1f5e1
   type PublishOrderCreated fill:#fff4e1
   type PublishPaymentAuth fill:#fff4e1
   type PublishStockReserved fill:#fff4e1
   type PublishShipmentCreated fill:#fff4e1
   type PublishPublicEvent fill:#fff4e1
   type OrderDB fill:#e1f0ff
   type PaymentDB fill:#e1f0ff
   type InventoryDB fill:#e1f0ff
   type ShipmentDB fill:#e1f0ff
   type UpdateOrderConfirmed fill:#e1f0ff
   type UpdateOrderShipped fill:#e1f0ff
   type PaymentGateway fill:#ffe1f5
   type CarrierAPI fill:#ffe1f5