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BACKEND & PLATFORM ENGINEERING

Summary: Built a ~42,000-file, framework-free PHP backend from first principles, including a hand-rolled database abstraction layer, ID-generation and encoding schemes, schema-introspecting guards, soft-delete + audit conventions, and the shared system primitives (sanitization, error handling, caching, encoding) that the entire platform is built on.

Monolith

Description: Designed and sustained a very large PHP codebase without a web framework or ORM, relying instead on explicit, uniform conventions and a shared primitive library.

Characteristics

Engineering Judgment

Data Layer

Description: Engineered a raw-SQL abstraction layer (~2,300 lines) that provides safety, routing, and audit without an ORM.

Features

Connection Routing: Database-code convention {schema}_{tier} resolves to per-environment config; primary / read-replica / analytics-replica tiers.

Connection Pooling: Persistent connections cached per database code within a request.

Crud Family: A uniform get/insert/update/delete/restore/value function family passed a shared context object.

Schema Guard: First-write column introspection auto-filters unknown fields and auto-detects the primary key and JSON columns (skipping double-escaping on JSON payloads).

Query Modes: Echo / trace / verbose / dry-run modes for safe debugging in non-production.

Multi Db Transactions: Cross-database transactions with named savepoints (start / commit / rollback per identifier).

Data Integrity Conventions

Description: Established platform-wide conventions that make destructive operations safe and every mutation auditable.

Soft Delete: Rows are never physically dropped, a status column marks active vs. deleted vs. inactive; delete and restore are status toggles.

Status State Machines: Multi-field status precedence (current > cancel > operate > reserve) supports complex booking lifecycles without ambiguous state.

Audit Stamping: Every insert/update stamps creator and modifier identity from the request context.

Entity Tracking: A dedicated entity-tracking scheme pre-allocates platform-wide unique IDs before domain rows are written, enabling cross-domain dedup and reconciliation (parent/uncle linkage for multi-level relationships).

Identifiers

Description: Designed the platform's identifier and encoding schemes to keep internal keys off the wire and IDs collision-free at scale.

Schemes

Primitives

Description: Built the shared system layer that every domain relies on.

Modules

Sanitization: Global input cleanup with HTML-entity encoding on the way in and decode on the way out; SQL-safety applied inside the write path.

Error Handling: Custom error handler with per-datastore failure handlers and environment-gated verbosity.

Caching Helpers: Cache get/set/increment/hash/TTL helpers over the external cache tier.

Encoding Helpers: Bidirectional numeric↔alpha, key↔ID, and public-code generation utilities.

Response Builder: A single response structure serialized to any supported wire format.

Domain Breadth

Description: Implemented business logic across a wide functional surface, all on the shared primitives above.

Domains

Cross Reference

Modern Backend

Description: Beyond the framework-free PHP monolith, architected a separate production backend on a modern, opinionated TypeScript stack - proving the same platform-engineering instincts transfer across paradigms.

Stack

Conventions Carried Across

Engineering Judgment: Chose a batteries-included framework here (vs. the deliberately framework-free monolith) because a small / AI-executed team benefits from strong conventions and guard-rails baked in. See COMP-21 for the surrounding distributed architecture.

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