Building Shoots: a hybrid event-driven agent system for photography

I created this article for the purposes of entering the All Things Agentic Hackathon. Shoots is an Android and web photography Companion. A photographer takes ordinary Shots. Shoots reviews them in the background, preserves the Evidence behind its reading, and can offer one optional Experiment when the record supports it. This is the technical version of the project. It is about how a file becomes a durable learning record, how the agents communicate, and where I deliberately refused to let a model make the decision. The design in one sentence The model panel reads a single Shot. The system around it does the work: it creates a durable Run, moves tiny events through independently retryable stages, re-reads state at every boundary, records every outcome, and only settles a Shoot after every member Run is accounted for. That distinction matters. I did not want a chain of agents passing prose to one another until it sounded convincing. I wanted constrained model calls inside a workflow whose state, retries, and outputs could be inspected later. Repository structure The codebase is deliberately split by responsibility rather than by screen or agent name: android/ phone/ # approved Camera media work/ # background upload and retry data/ # cache, API, identity ui/ # Android screens backend/app/ api/ # FastAPI ingress and push endpoints domain/ # pure rules and state transitions imaging/ # EXIF, pixels, visual artifacts agents/ # ADK agents and prompts services/ # workflow orchestration infra/ # storage, Pub/Sub, Drive, secrets frontend/src/ stores/ # API and SSE state pages/ # web audit desk components/ # receipts and visual Evidence infra/ # Google Cloud deployment and Scheduler The important boundary is domain/ . It has no I/O. It owns the rules that must be reproducible: grid-cell conversion, taxonomy validation, panel consensus, Criteria checks, Technique Map projections, and Run state transitions. services/ can call models and storage. domain/ cannot. Two kinds of orc