Eder Gutiérrez

Selected engineering work

Systems, pipelines, and tools built to solve concrete engineering problems.

Flagship: GTFS Realtime Stream Engine

A real-time transit data pipeline that transforms raw vehicle telemetry into validated, enriched event streams.

Consumes the MBTA's raw binary GTFS-Realtime VehiclePositions protobuf feed on a 15-second interval. Decodes the binary payload, validates telemetry integrity, enriches each ping against GTFS-static stop/trip metadata, and publishes normalized JSON events to Apache Kafka. Downstream DuckDB analytics perform deduplication, data-quality scoring, and temporal validation of schedule adherence.

┌─────────────┐   ┌──────────────────┐   ┌───────────────┐   ┌────────────────┐
│   INPUT     │   │   PROCESSING     │   │   STREAMING   │   │   ANALYTICS    │
├─────────────┤   ├──────────────────┤   ├───────────────┤   ├────────────────┤
│ MBTA Feed   │──→│ Protobuf Decoder │──→│ Kafka Producer│──→│  DuckDB        │
│ .pb payload │   │ gtfs-realtime    │   │ raw.vehicle   │   │  deduplication │
│ 15s poll    │   │ bindings         │   │ -positions    │   │  data quality  │
└─────────────┘   │ TypeScript/Node  │   │ 4 partitions  │   │  temporal val  │
                  └──────────────────┘   │ KRaft mode    │   └────────────────┘
                                         └───────────────┘

[TypeScript] [Apache Kafka] [DuckDB] [Protobuf] [GTFS] [Docker] [Vitest]

Repository

Autonomous AI Code Agent

An experimental CLI agent that uses an LLM with tool calling to read, write, and execute code in a sandboxed workspace.

A Python CLI that bridges a large language model to real filesystem operations. The agent receives a task, calls Gemini's function-calling API to decide which tool to invoke, executes the tool in a confined working directory, and feeds the result back into the loop — repeating until the model signals completion or an iteration cap is reached.

USER TASK
     │
     ▼
 ┌───────────────────────────────┐
 │  LLM  Gemini API              │
 │  function-calling enabled     │
 │  iterative loop               │
 │  memory of prior tool results │
 └───────────────┬───────────────┘
                 │ selects tool
                 ▼
        ┌──────────────────┐
        │  TOOL SELECTION  │
        │  read / write /  │
        │  execute         │
        └──────┬───────────┘
               │
               ▼
        ┌────────────────────────┐
        │ SANDBOX EXECUTION      │
        │ working-directory      │
        │ isolation              │
        │ read file · write file │
        │ run command · list dir │
        └──────────┬─────────────┘
                   │
                   ▼
              ┌──────────┐
              │  RESULT  │
              │ + prior  │
              │ context  │
              └────┬─────┘
                   │
        feedback ↺─┘
configurable iteration cap prevents runaway loops

[Python] [Gemini API] [Bash] [Git]

Repository

From scratch: Static Site Generator

A custom-built Python SSG — written from scratch to understand how tools like Jekyll and Hugo work under the hood.

Transforms a directory of Markdown files and static assets into a complete HTML website. The entire engine — block parsing, inline conversion, an intermediate TextNode representation, and a Composite-Pattern HTML node tree — was built from the ground up as a learning project. No third-party SSG libraries.

Markdown Files        Block Parser        Inline Converter      TextNode IR       HTML Renderer        HTML output
(content/)           (md-blocks.py)     (md-inline-          (textnode.py)     (htmlnode.py)       (docs/)
                     ┌──────┐             converter.py)                       ┌──────────┐
                     │head- │             ┌──────────────┐                    │Leaf-     │
                     │ings  │             │bold · italic │                    │Node ·    │
                     │lists │             │code · links  │                    │Parent    │
                     │code  │             │· images      │                    │Node      │
                     │block-│             └──────────────┘                    │recursive │
                     │quotes│                                                 │rendering │
                     │parags│                                                 └──────────┘
                     └──┬───┘
                        │
                        ▼
              recursive directory walk → mirrors source tree
this portfolio is generated by the same SSG

[Python] [unittest] [Regex] [Composite Pattern]

Repository