Implementation Strategy and Parallel Work

Core idea

Good architecture creates safe parallelism. When modules, interfaces, responsibilities, and dependencies are defined clearly, implementation can be divided across engineers, teams, or AI agents without colliding.

Solution Strategy
        ↓
Building Blocks
        ↓
Interfaces
        ↓
Implementation Lanes
        ↓
Implementation Slices
        ↓
Parallel Work
        ↓
Integration
        ↓
Verification

AIDD-17 turns architecture into implementation lanes.

Why parallel work fails without boundaries

AI can generate software quickly. The hard part is coordination. When multiple agents work against vague boundaries, they collide — editing the same files, inventing different interfaces, duplicating responsibilities, changing architecture decisions, expanding scope, and breaking integration.

AIDD-17 reduces this by defining work boundaries before implementation begins.

Implementation strategy

The implementation strategy explains how the system will be built. It should describe:

the chosen implementation approach
module boundaries
dependency order
which work can run in parallel
which contracts must be defined first
how integration will happen
how verification will happen

Example:

The system will be implemented by module boundary. The web application, backend POST /documents endpoint, and document storage adapter may be implemented in parallel once the POST /documents contract and the document record are defined.

The text processing worker depends on stored document records. The search index depends on processed text. Question answering depends on indexed chunks.

No module may change a shared interface without updating the interface definition and notifying dependent slices.

Module breakdown

A module is an implementation boundary. Each module should have one clear responsibility.

Responsibility:
  Accept document save requests, validate content, create document records,
  and coordinate document storage.

Inputs:
  POST /documents request.

Outputs:
  Document ID, save status, controlled error responses.

Depends on:
  Document storage service, application database.

Can be implemented in parallel with:
  Web application document input, if the POST /documents contract is stable.

Must not implement:
  Text processing, indexing, or question answering.

Dependency map

The dependency map defines what must happen before other work can begin. It tells humans and AI what can safely happen at the same time.

Shared contracts required first:

Document record
POST /documents
Save error response format

Parallel after contracts:

Web application document input
Backend Document API
Document storage adapter

Sequential dependencies:

Text processing worker depends on stored document records.
Search indexing depends on processed text.
Question answering depends on indexed chunks.

Implementation lanes

An implementation lane is a stream of work aligned to a module, component, service, or boundary. Each lane can be assigned to a person, team, or AI agent.

Lane: Web Application Document Input
  Module:    Web application
  Depends on: POST /documents contract
  Produces:  Document input component, client validation, UI tests

Lane: Backend Document API
  Module:    Backend API
  Depends on: Document record definition
  Produces:  Save endpoint, backend validation, API tests

Lane: Storage Adapter
  Module:    Document storage service
  Depends on: Storage configuration
  Produces:  Storage implementation and storage tests

Parallel slices

Implementation slices can run in parallel when their dependencies and interfaces are clear.

IMP-001: Define save contracts
  Blocks:
    - IMP-002 Web Application Document Input
    - IMP-003 Backend Document API
    - IMP-004 Storage Adapter

IMP-002: Web Application Document Input
  Depends on: IMP-001 Define save contracts
  Can run in parallel with:
    - IMP-003 Backend Document API
    - IMP-004 Storage Adapter
  Integration point: POST /documents contract

Integration plan

Parallel work requires an integration plan. Without one, parallel work creates merge risk and behavioural drift.

Define shared contracts.
Implement modules in parallel.
Run module-level tests.
Merge the storage adapter.
Merge the backend API.
Merge the web application changes.
Run end-to-end save verification.
Update the AIDD-17 project definition if contracts changed.

Rules for parallel AI work

When multiple AI agents work in parallel:

each agent receives one implementation slice
each slice has a defined module or lane
each slice lists expected files or areas to change
each slice lists files or areas not to change
each slice defines shared contracts
each slice defines dependencies
each slice defines verification
no agent may change another lane’s contract without explicit approval
no agent may implement out-of-scope work
each agent must return assumptions, files changed, tests added or changed, and verification performed

Summary

AIDD-17 is not just documentation — it is a way to create controlled implementation boundaries. When modules, contracts, dependencies, and slices are defined, software can be implemented in parallel without losing control.