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Emmanuel Cousin

Senior Software Engineer
Technical Lead & Engineering Mentor
Payments and AI at Circle
I orchestrate AI workflows to ship faster and help teams build better software.

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Projects

I build tools for Even G2 glasses and Ruby applications, alongside my payments and AI work at Circle and earlier contributions to Gumroad.

Even G2 glasses

Even Terminal OpenCode

AI sessions on Even G2 glasses

Node.js OpenCode

Connects Even Terminal directly to OpenCode so I can follow AI sessions, approve actions, and answer agents’ questions from Even G2 glasses. Shows live responses and compact summaries of what the agent is doing.

Keeps session history available while agents work and restores pending questions and approvals after a disconnect. Each approval stays tied to its session. A missing or invalid answer never grants permission.

GitHub MIT license

Glint G2

Messaging and email on Even G2 glasses

Node.js Whisper

Read Signal, WhatsApp, and HEY conversations on Even G2 glasses and reply by voice. A bridge running on your own computer connects the glasses to each service over a private network and transcribes spoken replies.

Built a shared runtime for the glasses and mobile companion, with a single app that lets you switch between all three services.

GitHub

Ruby Gems

Ruby

Use jsonapi-serializer with Grape. Provides formatters and a model parser for automatic Swagger response documentation via grape-swagger.

GitHub RubyGems
Ruby

Store and access deeply nested data structures within ActiveRecord columns. Generates accessors for every level of nested hashes with automatic typecasting. 

deep_store :settings, {
  notifications: { push: true, email: true }
}
user.push_notifications_settings # => true
GitHub RubyGems
Ruby

Object-level caching for ActiveModel. Cache strings, integers, decimals, datetimes, lists, and JSON directly on your models with a simple DSL. 

class User
  include ActiveModel::Caching
  cache_string :session_token
  cache_integer :view_count
end
GitHub RubyGems
Ruby

A fluent Ruby DSL for building InfluxDB Flux queries. Chainable API for constructing queries with measurements, fields, tags, aggregations, and more. 

InfluxDB2::QueryBuilder.new(bucket: 'sensors')
  .measurement('device_metrics')
  .fields('cpu', 'memory')
  .range(start: 24.hours.ago)
  .aggregate_window(every: '5m', fn: 'mean')
  .to_flux
View PR
Ruby

A Ruby client for the ProvetCloud API, used by veterinary practices for practice management.

GitHub RubyGems

Applications

Parkour Paris (pkp)

Live application

Rails Hotwire

Back-office platform for Parkour Paris, enabling members to register for parkour classes across Paris. Full-featured scheduling, payments, and member management.

Live Site GitHub

ActivityPub Engine

Rails Engine

Rails

A Rails engine implementing the ActivityPub protocol for federated social networking. Enables Rails apps to join the Fediverse with customizable authentication and actor management.

GitHub

Contributions

Circle

Payments platform · March 2026 to present

AI + payments

I’ve worked on checkout security, AI tools that help admins manage payments, and Stripe account setup inside Circle. I also contribute to the team’s AI agent instructions and review process.

Selected work Click to expand
  • Safer checkout: protected payment details from unauthorized changes and prevented duplicate purchases when someone clicks or retries more than once.
  • Membership management with AI: business owners can change subscriptions through a conversation and confirm the changes before they take effect.
  • Stripe setup inside Circle: business owners can connect payments without leaving Circle, with AI help to explain missing account details.
  • Payment reliability: fixed unfinished purchases that left unwanted subscriptions behind and billing records that no longer matched Stripe.
  • Paywalls AI: ported the team’s internal AI framework to OpenCode, giving the team a choice of AI providers without depending on Claude.

Gumroad

73 merged PRs

Rails React

Major contributor to Gumroad's open-source codebase. Led the frontend migration from ERB/React on Rails to Inertia.js/React, migrated the admin panel, and shipped features including Black Friday 2025 and subscription lifecycle improvements.

Notable PRs Click to expand
View all PRs