Reverse Engineering and Detailed Requirements Mapping in an Undocumented Application

From a formatting task to uncovering a critical scope gap: how we transformed an undocumented project through field immersion and reverse engineering.

01 Overview

The Context: Short-term freelance contract to structure use case documentation for a mature corporate application, lacking updated documentation and marked by accumulated maintenance from various developers over the years.

My Role: Initially hired for visual layout and aesthetic finishing of the documentation; organically expanded into Requirements Analysis, Process Mapping (Discovery), and Technical Writing of Use Cases in partnership with the QA analyst.

The Impact: Early identification of a critical scope misalignment (initial mapping covered less than 30% of the actual system), field immersion with multiple user profiles, and delivery of an extremely thorough document on schedule, receiving expressive praise from the client.

02 The Challenge and Initial Scenario

The client needed to consolidate application specifications to understand and organize their routines. However, the project presented an invisible challenge:

The Technical Scenario: Because the system had passed through several developers over time - each applying their own development standards - the application lacked unified, updated documentation.

The Partial Survey: One of the company's partners performed a preliminary macro survey and selected a limited set of use cases, categorizing them by complexity (simple, medium, and complex) to fit the client's available budget.

The Stipulated Role: I was hired alongside a QA analyst (with whom I had no prior connection) strictly to layout and provide visual finishing for the final document to be delivered.

03 The Turning Point: Field Investigation and Reality Alignment

Right in the first few days of on-site allocation alongside the QA analyst, we realized the documentary scenario was completely disconnected from the software reality:

Discovering the Gap: Within a few hours of analysis, it became clear that the initial list didn't cover even 30% of the application's actual scope. Furthermore, several complex routines had been underestimated as "simple."

Multi-User Ecosystem: The tool served a wide range of roles and hierarchical levels - from the factory floor to end-user support, passing through IT and commercial departments.

Proactive Action (Going to the Field): Instead of limiting myself to formatting a document according to the initial scope, I decided to embrace the problem's complexity because I understood the test analyst would need reinforcement. We requested and conducted direct interviews with users at their workstations: we visited the factory, talked with support, aligned with the IT team, and investigated commercial routines to truly understand how the tool was operated by everyone in practice.

04 Execution, Dependencies, and Technical Detail

To accurately describe each use case, it was necessary to navigate different system access perspectives.

Acquiring Skills: As a designer and front-end developer outside my traditional comfort zone, I quickly grasped use case writing methodologies and the technical terminologies needed to structure the document.

The Dependency Web: The work proved extremely complex because it was impossible to treat a use case in isolation without bumping into one or two related ones. Because flows crossed paths and failures in one routine directly impacted others, we developed highly detailed documentation to tie together all exceptions and dependencies.

05 Results and Value Generated

Despite all the challenges of hidden scope and lack of prior records, the project was an absolute success.

• Recognition: The delivered documentation far exceeded the original scope in terms of depth, precision, and practical utility, generating expressive praise from the client.
• Value Lesson (Soft Skills): The case demonstrates the value of systemic thinking and proactivity. An initially aesthetic task transformed into a high-complexity structural analysis that protected the technical clarity of the client's project.