systems shared backend workflows

Shared backend workflows

Active contributors: Douwe de Vries

Purpose

The shared backend workflow layer coordinates CSV loading, mapping suggestions, comparisons, export, pair-order files, and comparison snapshots. It is the main API called by both Axum handlers and Tauri commands.

Directory layout

src/backend/
├── workflow.rs
├── requests.rs
├── validation.rs
├── error.rs
├── store.rs
└── session.rs

Key abstractions

Name	File	Description
load_csv_workflow	src/backend/workflow.rs	Parses bytes or paths, enforces file size, builds file-load metadata.
apply_loaded_csv_for_session	src/backend/workflow.rs	Stores loaded CSV data and clears stale results.
suggest_mappings_for_session	src/backend/workflow.rs	Suggests column mappings using headers and loaded values.
run_comparison_for_session	src/backend/workflow.rs	Validates request, executes comparison, writes results if inputs are still current.
CsvAlignError	src/backend/error.rs	Shared error type serialized through HTTP and Tauri.

How it works

graph TD
    Adapter[HTTP handler or Tauri command] --> Workflow[src/backend/workflow.rs]
    Workflow --> Validation[src/backend/validation.rs]
    Workflow --> Store[src/backend/store.rs]
    Workflow --> Csv[src/data/csv_loader.rs]
    Workflow --> Mapping[src/comparison/mapping.rs]
    Workflow --> Engine[src/comparison/engine.rs]
    Workflow --> Responses[src/presentation/responses.rs]

Loading

Workflow functions keep expensive work outside long store locks where possible. run_comparison_for_session reads the current Arc<CsvData> inputs and data_revision, runs comparison, then writes results only if the session still points at the same inputs.

Integration points

src/api/handlers.rs wraps blocking workflow calls for Axum. src-tauri/src/commands.rs calls the same functions directly for desktop. Frontend state expects response shapes from src/presentation/responses.rs and src/backend/requests.rs.

Entry points for modification

New product behavior should usually start here. Add a workflow function, keep validation in src/backend/validation.rs if it is request-specific, add integration tests under tests/, and only then wire HTTP, Tauri, and frontend UI.

Key source files

File	Purpose
src/backend/workflow.rs	Shared workflow orchestration.
src/backend/requests.rs	Request and persistence DTOs.
src/backend/validation.rs	Comparison request validation.
src/backend/error.rs	Error shape and status mapping.
src/presentation/responses.rs	Public response DTOs.