# Monica Application Modular Monolith > DDD modular monolith architecture guidance for Monica application projects. Use when creating or extending a bounded context under Domains, planning the strict solution-project dependency chain across Platform layers, placing project-common versus subdomain-only library references, shaping Platform.Protocol/PublishedLanguages, defining domain-owned Application layout, merged domain packages, and… - **Type:** Skill - **Install:** `agentstack add skill-tairitsua-monica-monica-application-modular-monolith` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [Tairitsua](https://agentstack.voostack.com/s/tairitsua) - **Installs:** 0 - **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [Tairitsua](https://github.com/Tairitsua) - **Source:** https://github.com/Tairitsua/Monica/tree/dev/.claude/skills/monica-application-modular-monolith - **Website:** https://monica.dpdns.org/ ## Install ```sh agentstack add skill-tairitsua-monica-monica-application-modular-monolith ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Monica Application Modular Monolith ## Overview Use this skill to structure a Monica application solution as a modular monolith with explicit subdomain boundaries. It keeps the deployment single while preserving contract-first collaboration and clear ownership per bounded context. ## Workflow 1. Read [00-solution-layout.md](references/00-solution-layout.md) to understand the target domain-first structure. 2. Use [01-create-subdomain-and-domain.md](references/01-create-subdomain-and-domain.md) when adding a new bounded context. 3. Use [02-protocol-platform-and-internal-collaboration.md](references/02-protocol-platform-and-internal-collaboration.md) before introducing cross-domain requests, DTOs, or events. 4. Use [03-boundaries-dependencies-and-persistence.md](references/03-boundaries-dependencies-and-persistence.md) to keep host composition and persistence ownership coherent. 5. Hand unit implementation to `monica-application-project-unit-development`, then finish with [04-delivery-checklist.md](references/04-delivery-checklist.md). ## Core Rules - Split the solution by bounded context under `Domains/`, not by global `Application`, `Domain`, or `Infrastructure` buckets. - Each bounded context under `Domains/` uses a single `Domains.{Subdomain}.csproj` that keeps `Application`, domain models, and domain-owned infrastructure together. - Keep the shared platform split explicit: `Platform.BuildingBlocks` for project-agnostic infrastructure extensions, `Platform.Infrastructure` for solution-owned infrastructure wiring, and `Platform.Protocol` for shared business language. - Use the strict solution-project reference chain `AppHost -> Domains.{Subdomain} -> Platform.Infrastructure -> Platform.Protocol -> Platform.BuildingBlocks`. - Put project-common library references in `Platform.BuildingBlocks`. Keep subdomain-only package references in the owning `Domains.{Subdomain}.csproj`. - Keep cross-domain dependencies pointed at `Shared/Platform.Protocol/PublishedLanguages`, consuming shared `Contracts/` and only the deliberate `Implementations/*` surfaces exposed there. Do not reference another domain's internal implementation directly. - Keep domain-owned application units in `Application/HandlersCommand`, `Application/HandlersQuery`, `Application/HandlersEvent`, and `Application/BackgroundWorkers`. - Keep repository implementations and `DbContext`-related files in `Repository/`, and keep pure helper code in `Utilities/` with `Utils*` names. - When a domain exposes `ApplicationService` HTTP endpoints through default routing, keep one assembly-level `AutoControllerConfig(DefaultRoutePrefix = "api/v1", DomainName = "{Subdomain}")` file in the domain project root instead of repeating class-level `Route` attributes on every handler. - AppHost entry projects are composition-only entry points. Keep them down to the project file and `Program.cs`; do not place business ProjectUnits there. - When AppHost composition needs a `Configuration` ProjectUnit during registration, register `Mo.AddConfiguration(...)` first and call `Mo.RegisterInstantly(builder)` before later registrations depend on those options. - Keep `.slnx` solution folders aligned with the physical layout under `src/AppHost`, `src/Shared`, and `src/Domains`. - Treat the modular monolith as one deployment, not as hidden microservices in the same repository. ## Reference Navigation - Solution structure: [00-solution-layout.md](references/00-solution-layout.md) - New subdomain/domain workflow: [01-create-subdomain-and-domain.md](references/01-create-subdomain-and-domain.md) - Protocol platform and collaboration: [02-protocol-platform-and-internal-collaboration.md](references/02-protocol-platform-and-internal-collaboration.md) - Boundaries, dependencies, and persistence: [03-boundaries-dependencies-and-persistence.md](references/03-boundaries-dependencies-and-persistence.md) - Completion checklist: [04-delivery-checklist.md](references/04-delivery-checklist.md) ## Scope Notes - This skill defines domain boundaries and composition rules inside one deployment. - Use `monica-application-project-unit-development` whenever the next step is to implement requests, handlers, entities, repositories, events, configurations, or jobs. ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [Tairitsua](https://github.com/Tairitsua) - **Source:** [Tairitsua/Monica](https://github.com/Tairitsua/Monica) - **License:** MIT - **Homepage:** https://monica.dpdns.org/ Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-tairitsua-monica-monica-application-modular-monolith - Seller: https://agentstack.voostack.com/s/tairitsua - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.