Buyer journey
Discover → Choose → Purchase
Search the catalog, inspect condition and images, add an item to the cart, then use guest or account checkout with shipping and tax in the order totals.
Engineering case / 02 / Columbus Direct Edge
Marketplace commerce.
Connected operations.
Columbus Direct Edge connects resale catalog discovery, buyer accounts, auctions, checkout, inventory reservation and seller operations in a layered commerce application. Its engineering focuses on the transitions that matter: validating bids, reserving stock against the correct order, verifying payment events, finalizing purchases and keeping fulfillment and reporting connected.
Functional scope
The working depth behind the storefront.
Twelve capability areas connect the buyer’s purchase to the seller’s daily work. Explore the functions, follow the transaction, then inspect the engineering and measured scope.
Connected workflows
From discovery to operating records.
Auction journey
Verify → Bid → Checkout
A verified buyer places a bid through a guarded transaction. Winning-bid and buy-now workflows connect the auction result to checkout.
Inventory & payment
Reserve → Verify → Finalize
Stock is reserved against the intended order. Payment-event checks and record locks coordinate finalization, repeats and expiration handling.
Seller journey
Publish → Fulfill → Review
Maintain listings, review orders and update fulfillment. Sales, shipping and tax reporting keep the seller’s operating records connected.
Engineering decisions
The hard part is the state change.
Catalog & repositories
A listing-repository contract separates storefront behavior from database and snapshot catalog implementations. Image inspection and import commands support a changing resale inventory.
Auctions & concurrency
Authenticated, verified bidding is rate-limited. Bid handling uses a database transaction and row lock; auction checkout connects the winning-bid state to a purchase workflow.
Stock reservation & retries
Checkout reserves listing inventory against an order. Open-session reuse and reservation ownership keep retries tied to the intended purchase. Expiration handling checks ownership before releasing stock.
Payment events & finalization
The webhook verifies an HMAC signature, timestamp, canonical event shape and configured mode. Paid-state handling verifies totals and locks the relevant records; repeat delivery and late events have explicit paths.
Seller operations
Protected tools support creating, editing, duplicating and publishing listings; reviewing orders; updating fulfillment; and inspecting sales, shipping and tax records.
Buyer experience & protection
Buyer accounts, email verification, order history, shipping estimates, tax calculation and cart flows are supported by request guards and contextual status messages.
Source architecture
A layered commerce application.
58
Declared HTTP route definitions
21
Controller source files
9
Schema migration files
01 / EXPERIENCECatalog · Buyer account · Seller workspace
02 / APPLICATIONRoute guards → Controllers → Repositories & services
03 / STATEListings · Bids · Orders · Users · Import records
04 / PAYMENT BOUNDARYCheckout gateway → Signed event → Guarded order transition
Maintained stack: PHP ^8.3, Laravel locked at 13.12.0, Blade templates, JavaScript/CSS and MySQL/MariaDB migrations. Source structure includes six model classes and 37 Blade views excluding the framework welcome template. Route definitions are a source count, not a load-capacity measure.
Measured scope
Marketplace workflows behind the storefront.
The census separates application logic, views, assets, schema migrations and delivery scripts from the automated verification source.
15,004
Nonblank implementation lines
128
Unique implementation files
10,180
Separate verification-source lines
Physical source lines excluding blank lines; includes comments, templates and styles. Third-party packages, generated outputs, evidence archives and exact duplicate files are excluded. Verification code is counted separately.
Inspect the component breakdown
| Area | Unique files | Nonblank lines |
|---|---|---|
| App | 49 | 5,374 |
| Bootstrap | 2 | 34 |
| Config | 15 | 1,249 |
| Database | 10 | 400 |
| Public | 4 | 1,859 |
| Resources | 39 | 5,164 |
| Routes | 2 | 138 |
| Scripts | 6 | 763 |
| Vite.Config.Js | 1 | 23 |
Inspect the language breakdown
| Language / file type | Unique files | Nonblank lines |
|---|---|---|
| CSS | 2 | 1,164 |
| JavaScript | 4 | 748 |
| PHP / templates | 117 | 12,523 |
| PowerShell | 5 | 569 |
Current rebuild assessment / USD
$187K–$459K
Estimated engineering replacement cost
The work to reproduce equivalent functionality, integration and delivery discipline with a competent team using established frameworks and contemporary development tools.
- Lower scenario
- 1,700 hours × $110
- Central scenario
- $309,400
- Upper scenario
- 3,060 hours × $150
September 5, 2026 · AI-assisted rebuild estimate, published by Bennett Edge Group. Measures replacement effort, not historical spending or company market value. Inspect the methodology →
Recorded verification / September 5, 2026
Inspect the confirmed behaviors.
Selected passing suites from an isolated copy of the maintained code, using an in-memory database and fixture payment gateways. The complete result is shown below, with the detailed accounting in the methodology.
| Confirmed suite group | Tests | Assertions | Scope |
|---|---|---|---|
| Checkout & inventory | 28 passed | 777 | Checkout totals, repeat-session reuse, reservation ownership, payment finalization and stale-event handling. |
| Auctions | 3 passed | 421 | Bidding, buy-now behavior and winning-bid checkout in database-backed fixtures. |
| Payment event verification | 17 passed | 155 | Signature checks, timestamp rejection, mode matching, malformed events, idempotent delivery and guarded diagnostic forwarding. |
| Seller operations | 59 passed | 1836 | Listing management, order workflows, report reconciliation, tax views, access gates and safe failure presentation. |
| Buyer access & cart | 34 passed | 596 | Cart behavior, account registration, guest checkout, signed-in order association and email verification. |
| Security, contact & imports | 32 passed | 265 | Security headers, request guards, isolated contact behavior, catalog-import command fixtures and deployment-source checks. |
| Calculation & image units | 11 passed | 29 | Image validation and shipping/tax calculation under configured fixtures. |
These groups contain 184 passing tests. They demonstrate behavior under the stated fixtures; assertion counts are not a coverage percentage. View the complete test accounting →
Complete recorded run: 226 tests · 224 passed · 2 assertion failures · 0 errors · 4,725 assertions. The two follow-ups concern payment-setup guidance and configurable parent attribution in Terms. The run used an isolated application copy, SQLite in memory, fixture gateways and mail, and disabled outbound socket/cURL functions. Application tests were not rerun for this content update.
Let’s talk
Discuss the marketplace engineering.
Review catalog architecture, seller workflows, payment-state handling or the work required to reproduce equivalent capability.