# Architecture > Reuse org catalog resources when deriving or enriching a component's design — deciding the component decomposition, filling a scaffolded design.json (language, dependencies, description, pinned skills), or resolving/reconsidering any dependency. - Skill: `wso2/architecture` (Agent Skill) - Install (CLI): `npx skillmds@latest add wso2/architecture` - Raw SKILL.md: https://api.skillmd.com/api/skills/wso2/architecture/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Web & Frontend - Author: wso2 (https://skillmd.com/u/wso2) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/wso2/architecture --- # Architecture Component decomposition and per-component facts. The cell (`cell-design` skill) declares WHAT exists; this skill owns deciding the decomposition and ENRICHING each component's `design.json`. ## Scaffold first, enrich second When the cell is saved, the platform scaffolds `specs/design/components//design.json` for every deployable component — the mechanical fields (name, type, version, buildpack, appPath, entrypoint, a default exposure) plus a `"language": "TBD"` sentinel. Your job is the JUDGMENT fields, and the build gate refuses a deployable component left unenriched: - **language** — **Language is decided in this order**: the organization skill's Tech stack default first, then a language the requirements name, then the platform default — **Ballerina** for backend services, TypeScript for web apps. Replace the scaffold's `"language": "TBD"` sentinel with the decided value; the build gate refuses a component whose language is still TBD. That choice is a fact you record, not a preference you re-derive per component: write it as the component's `language` and pin the matching stack skill in `skillsPinned`. - **stories** — the PRD story numbers this component serves, as an integer array (e.g. `"stories": [1, 2, 4]`). Claim every story the component actually serves: the build gate refuses the tag while any PRD story is claimed by no component. - **dependencies** — the playbook below. - **description** — one paragraph: single responsibility, port/entrypoint expectations, and what it explicitly does NOT do. - **skillsPinned** — After emitting or changing a component's design, record the skills that component's build actually needs as a `skillsPinned` array **inside that component's `specs/design/components//design.json`** — use the exact catalog names, e.g. a Ballerina API service → `["openapi-conventions", "ballerina"]` (a Go one → `["openapi-conventions", "go"]`); a web-application → `["wireframes", "react-webapp", ]`, where `` is the skill name in the **UI design system** section of the Organization defaults block in your instructions. A web app's UI toolkit is a settled organization decision, so pin it on **every** web-application rather than leaving it to a description to trigger — and read the name from that section every time instead of remembering one, because it differs per organization. If that section is absent or empty, pin only the two stack skills. Never substitute a design system the organization defaults do not name. **Pin the design system; do not consult it.** A design system is built against, not designed with — it is the coding run's to load, and its theming is a settled organization decision that no design-time question reopens. Never ask the user about colors, themes, or look and feel. Add `"api-management"` to any service that sits behind the gateway, and `"thunder-authentication"` to **both** sides of sign-in — the SPA *and* every protected backend it calls, since that skill owns how each resolves the caller's role. It is a JSON key on the component's design object, so include it when you write that `design.json` (addFile/editFile) — `design.json` is its only home. Each component carries only the skills its own build needs. Writing the whole enriched file yourself (removeFile + addFile with every field) is equally valid — the scaffold is a safety net, not a required intermediate. ## Deriving components — deployment units the requirements justify A component is one independently deployable unit, NOT a domain concept. The right number comes from the requirements: for every component you must be able to say "this deploys and evolves independently because ". Write that justification into the component's `description`. A requirement justifies a SEPARATE component when it shows: - a distinct user-facing surface — e.g. an internal admin portal AND a customer-facing app with different users and lifecycles → two web-applications; - a genuinely different runtime or scaling profile — e.g. an async worker/batch processor beside an interactive API, or a long-running AI/inference service; - a technology the rest of the system doesn't share — e.g. a Python ML service beside a Ballerina API; - an explicitly separate lifecycle or ownership stated in the requirements. Do NOT split by: - entity or domain concept — claims-service, users-service, receipts-service... is a domain model dressed as a topology; those are modules of ONE service; - layer — auth, notifications, file storage as own services when they are modules of the API; a single frontend split into `ui-shell` + `ui-pages` when it is one bundle; - infrastructure — api-gateway, database, queue, auth server are NEVER components; the platform provides them; - periodic work — a nightly digest or a cleanup sweep is a background task the owning service starts, not a component of its own. Only a genuinely different runtime or scaling profile (above) justifies splitting one off. When nothing above forces a split, a small system naturally lands at one service + one web-application — that is an outcome of the rule, not a target. Name components in kebab-case after their responsibility (`expense-api`, `expense-webapp`, `report-worker`). **Component `type` is a fixed vocabulary — use the EXACT string.** A backend is `"service"`; a browser app is `"web-application"` (OpenChoreo's own term). Write `"web-application"` verbatim — NOT `"webapp"`, `"web-app"`, or `"webApplication"` (those are rejected, and a wrong value silently breaks the app's deployment and runtime config). The `-webapp` in a component NAME is fine; the `type` is still `"web-application"`. Other kinds the requirements imply (`"scheduled-task"`, `"worker"`, …) are captured verbatim, but the platform installs component types for `service` and `web-application` ONLY — anything else records intent and does not deploy, so reach for one when the requirements truly force it, never as the default home for periodic work. ## Per-component design.json Each component's structured facts live in ONE JSON document (no markdown, no frontmatter). The platform validates each write against this schema and rejects violations: ```json { "name": "expense-api", // MUST equal the directory name "type": "service", // EXACT kind: "service" or "web-application" (NEVER "webapp"/"web-app"), or another the requirements imply ("scheduled-task", "worker", ...) "version": "0.1.0", // semantic version; 0.1.0 for a new component "language": "Ballerina", // implementation language — "Ballerina" for a service unless the requirements say otherwise; "TypeScript" for a web-application "buildpack": "docker", // always "docker" "appPath": "expense-api", // repo-relative source dir — the component name "entrypoint": "deployment/service", // deploy entry — PAIRS with `type`: "deployment/service" for a service, "deployment/web-application" for a web-application "exposure": "internet", // "internet" (public) | "intranet" (internal only) "dependencies": [ /* see below — every dependency edge touching this component appears here */ ], "description": "One paragraph: single responsibility, port/entrypoint expectations, and what it explicitly does NOT do.", "stories": [1, 2, 4], // PRD story numbers THIS component serves — the build gate refuses the tag while any story is claimed by nobody "skillsPinned": ["openapi-conventions", "ballerina"], // the skills this component's build needs — see the field above "endpoint": { "name": "http" } // optional; see below } ``` `name`, `type`, `version`, `language`, `buildpack`, `appPath`, `entrypoint`, `exposure`, `description`, `dependencies`, `stories` and `skillsPinned` are required — `stories` and `skillsPinned` are as required as the rest, and a component missing either fails the build gate, so emit them in the SAME write rather than as a follow-up edit. To CHANGE a design.json, re-emit the whole corrected file (removeFile + addFile) — never patch JSON with anchored edits. On INVALID_JSON or SCHEMA_VIOLATION, fix what the message lists and re-emit. `endpoint` is optional: omit it and a service's endpoint takes the default name `"http"`. Declare `{ "name": "" }` only when the endpoint must be named otherwise — `name` is the single source of truth the coding agent copies into `workload.yaml` and the managed-API gateway binds to. The port lives in `workload.yaml`, not here. **Platform-owned fields you never author**, in two kinds: - **Preserved verbatim** where the platform has already written them: `exposesAPI`, `componentAgentInstructions`, and any dependency `status`/`reason`. - **Recomputed and overwritten** on every save: a dependency's `wiring` object. The platform derives its `ref` and its env-var names from the dependency's name and its resource type's declared outputs, so anything you write there is discarded. `stories` is NOT in this class — it is yours to author, per the **stories** field above. ### dependencies — one entry per design.cell edge `dependencies` mirrors the DEPENDENCY edges of design.cell: every arrow between this component and another node appears here and vice versa — a mismatch is a defect. The `north ->` / `west ->` gateway arrows are **exposure**, not dependencies: they live in this component's `exposure` field and never become entries here. The platform enforces the membership half as you write: a dependency whose `name` is not a node the cell declares is refused (`UNKNOWN_DEPENDENCY`) with the cell statement to add. A resource you discover here — a database, a cache — is a cell node too: `editFile` `specs/design/design.cell` to add `component as "…" database` inside the cell before the design.json that depends on it, or the diagram will not draw what the build provisions. Each entry is a `kind` plus a `name`, and you pick the kind by WHAT the target is. The kind-only fields below are exhaustive: one of them on another kind is a schema violation that both the zod write-gate and the Go fold gate reject. ### The four kinds | `kind` | The target is | `name` comes from | Kind-only fields | Discover with | |---|---|---|---|---| | `component` | a SIBLING in this design that this component CALLS | the sibling's own name | — | this design | | `org-service` | a service ANOTHER project publishes for cross-project use | the provider's exact name, **copied verbatim** | — | `list_org_endpoints`, then `list_org_component_endpoints` | | `platform-resource` | a backing resource the platform provisions (database, cache, IDP) | **your choice** — it becomes the env-var prefix | `resourceType` (a registered type), `parameters` | `list_platform_resource_types` | | `external` | a system OUTSIDE the platform (a SaaS API, a legacy service) | a **Registered External resource**'s exact name, else a **new** name for a **Project External resource** | none on the component — the definition is the dependency's own file (below) | `list_external_resources` + `get_external_resource_schema`, else `web_search` | **Reuse.** Call that last column's tool before authoring the entry, and take the name and schema from the matching row rather than from the requirement's wording — a **Registered External resource** described as "transactional email delivery" is the right reuse for an "email" need even when its name (`sendgrid`) doesn't echo the requirement. When several rows could fill the role, the org-level one wins (a Registered External over a new Project External name; an org-service over a sibling you would otherwise add; a listed cluster resource type for `resourceType`). This step is done when every `external`, `org-service`, and `platform-resource` emitted this turn is taken from this turn's matching `list_*` result (exact `name` or `resourceType`), unless this turn is a user-asked reconsider. When nothing the catalog returns fills the role, omit the entry and list the gap under **Needs your input** rather than coining a name: a `resourceType` that was not in this turn's `list_platform_resource_types` result fails Build. ```json "dependencies": [ { "kind": "component", "name": "expense-api" }, { "kind": "platform-resource", "name": "orders-db", "resourceType": "postgres-cnpg" }, { "kind": "external", "name": "github", "description": "Call GitHub issues + PRs for the sync story." } ] ``` The `github` entry is a REFERENCE: its definition — provider, style, contract, config keys — is `specs/design/dependencies/github/dependency.json`, written once and shared by every component that uses it. A component's `description` on the edge says why THIS component uses it; the dependency's own description says what the system is. #### Reading a provider's real contract Once you have an `org-service` provider's name, call `list_org_component_endpoints` and base that dependency's `description` on the operations its contract actually exposes: | `spec.availability` | Where the contract is | |---|---| | `inline` | `spec.inlineContent` IS the OpenAPI document — read it directly | | `repo` | the row's `owner`/`repo`/`subdir`/`branch` locate the source: `search_remote_git_code` under that `subdir`, then `get_remote_git_file_contents` | | `none` | nothing resolvable — say so plainly in the `description`, never invent a shape | ### Traps - **Never the reverse edge.** Declare a dependency ONLY on the caller, naming the callee: a web-app depends on the API it calls; the API does not depend on the web-app. A component this one doesn't call is not a dependency of it — don't list one "for reference". - **A role is not a name.** The requirement says "the organization's directory service"; the provider is usually called something else (`employee-service`). The same for a `platform-resource`: the PRD names a capability, `resourceType` is the catalog row's `name` from this turn's `list_platform_resource_types`. Copy that `name`. Look it up — a name coined from the role or capability words matches no provider or type and hard-fails the build. - **A `platform-resource`'s `name` becomes the env-var prefix** for every one of its outputs (`orders-db` → `ORDERS_DB_HOST`, and for a SPA `window._env_.ORDERS_DB_*`), so pick a clear one: renaming it later renames the component's whole config surface. - **Secret-bearing dependencies belong on a `service`, not a `web-application`.** A web-application ships to the browser, so anything it holds is visible in dev tools — and *every* output of a `platform-resource` it declares is emitted into `window._env_`, so a database dependency on a SPA publishes its password. The secure default: attach the dependency to a backend `service` and give the web-app a `component` edge to it, so the service proxies and the SPA never sees the credential. A web-application may declare an `external` dependency directly only when NONE of its `config` keys need `secret: true` — a genuinely public API, or one the END USER authenticates with their own in-browser OAuth. The one exception is `thunder-app` (next bullet): its outputs are public OIDC client config by design. The schema does not reject a secret on a web-application, so apply this as the architect's judgment call, not a rule to route around. - **`thunder-app` is how sign-in happens, and nothing else provisions it.** When the spec implies users sign in, declare it on BOTH the SPA and each protected service under the SAME dependency `name` — that shared name is what ties sign-in to token-carrying API calls. With no such dependency the SPA deploys unable to sign in. `thunder-app` takes no `parameters`: `security-design` authors the Thunder client on `security.json`, and the platform registers the callback URI (`redirectUris` — platform-managed, never proposed here). `thunder-authentication` owns the coding-time rule, and `security-design` owns which roles sign in through it. ### Resolving an `external` dependency **One dependency, one definition.** An external dependency lives in its own directory, `specs/design/dependencies//`, and a component only references it by `name`. The write-gate refuses a component that names an external dependency whose directory has no `dependency.json` yet, so write the dependency file BEFORE the component that uses it (a `declare_plan` entry per dependency keeps the rail honest). The name is the same identifier everywhere: the directory, the cell's `south` node, the component's reference, and — for a reuse — the org registry. `dependency.json`: ```json { "name": "payment-provider", "description": "Charges the customer for shipping once a box is priced.", "provider": "Stripe", "style": "rest-api", "contract": "openapi.yaml", "provenance": { "sourceUrl": "https://…/spec3.json", "sha256": "…", "fetchedAt": "…", "sliced": true }, "config": [ { "key": "PAYMENT_API_KEY", "secret": true, "description": "Stripe secret API key" } ] } ``` Work each one in order: 1. **Reuse first.** Call `list_external_resources`. When a **Registered External resource** fits, write the stub `{ "name": "", "source": "org" }` — the platform fills provider, contract and config from the org record, and the build collects no values for it, because org values stay on the Registered name. Write consumption instructions into the dependency `description` — the row's consumption instructions and its org resource docs pointers, as the tool returns them — because the coding agent reads them there and never calls the catalog. Then stop. A user-asked reconsider may switch to a different Registered name, or create a **Project External resource** under a **new** name. 2. **The PRD names the service, or nobody has.** The user chooses providers; you never do. Two outcomes, never a `status`: - **The PRD's Product Decisions name a service for this capability** ("Payments: Stripe") → write `provider` + `style` and go on to the contract (step 3). An org or platform skill that mandates a vendor counts the same way. Nothing else does: "the requirement implies it", "this one is popular", "there is only one real option" are guesses, and a guess is the user's to make. - **No provider named** → write the NEED only: `name`, `description`, and `suggestions` — providers commonly used for this capability, from what you know, any number, each `{ "name", "style"?, "description"? }` with the one distinction that matters for THIS product. No `web_search`, no `provider`, no `style`, no `contract`, no `config` — the config keys follow the provider, and none is chosen. The definition then offers **Select a provider**, which runs the `resolve-dependency` flow: it asks the user, with your suggestions as the options, and does the research. This is the EXPECTED outcome for a choosable dependency; do not force a pick the PRD does not make. The dependency IS the service the product needs, so name it `-service` (`currency-service`, `payment-service`, `email-service`); the chosen system is its provider. 3. **Get the contract on disk — for a named provider only.** `style` says how: `rest-api` and `graphql` need a document in the directory (`openapi.yaml` / `schema.graphql`), `sdk` needs `sdk.json` (and the API slice beside it when the provider has one). The contract is a SLICE: name the operations the design's flows actually call and let `slice_openapi_spec` cut them from the provider's published document with their referenced schemas — it fetches outside your context, so the document's size does not matter — then `addFile` the returned content as `openapi.yaml` and copy the returned `provenance` into `dependency.json`. A user-supplied document goes through the same tool. With no document to be found, climb one rung: **derive** the interface from the provider's OWN developer reference when it names every operation the design calls with parameters and responses — `openapi.yaml` with `x-aep-derived: true` at the root and `x-aep-source: ` on every operation, `provenance. sourceUrl` = the reference's root page. That needs no permission: the dependency reads resolved, flagged *derived*. With no such documentation either, never guess during the design turn: leave `contract` unset, say so under **Needs your input**, and the `resolve-dependency` flow takes it from there (it may write an ASSUMED contract, but only under the user's authorization). This rung is for a NAMED provider only — an open capability gets no interface search at all. 4. **Derive `config` keys** from the contract — a `rest-api`'s `components.securitySchemes`, an `sdk`'s auth documentation — for a named provider only; a definition with no provider carries no keys (the gate refuses them). A reused Registered row already named the keys — keep them. 5. **Reference it** from each consuming component: `{ "kind": "external", "name": "", "description": "" }`. `style`, `package`, `specPath`, `suggestions`, `config` on the component are refused — they belong in the dependency file. ### Config-key conventions `config` is the env-var schema the consuming component codes against. Use `SCREAMING_SNAKE_CASE` keys and keep them minimal — only what the component reads. `secret` is opt-in: set `"secret": true` ONLY for credentials (they route through the secret path), and OMIT it entirely otherwise. Give each key a `description` saying what the value is and where the user finds it (`{ "key": "STRIPE_API_KEY", "secret": true, "description": "Your Stripe secret API key" }`) — the Build dependency drawer shows it under the field. For a NON-secret key whose sensible default you can infer, add `defaultValue` and the drawer pre-fills it (`{ "key": "AWS_REGION", "defaultValue": "us-east-1" }`). NEVER set `defaultValue` on a secret — a credential has no default to invent. An `external` dependency should almost always carry at least one key: the value-collection gate needs something to collect. #### How the platform derives status/reason You never author `status`/`reason`. The platform reads them off the dependency file at read time, first match wins: 1. `source: "org"`, or `name` matches a registered external resource → `resolved` (flagged `registered`) 2. no `provider` (`suggestions` open or not) → `unresolved`/`needs-input` — the user has not chosen a service; the definition asks them 3. a `style` whose contract is not on disk (no `openapi.yaml` / `schema.graphql` for `rest-api` / `graphql`; no `sdk.json` for `sdk`) → `unresolved`/`needs-contract` 4. a contract marked assumed with no user acceptance → `unresolved`/ `needs-acceptance` 5. otherwise → `resolved` — flagged `assumed` when the contract was accepted as an assumption, `derived` when it was written from the provider's own documentation, `sdk-only` when an `sdk` dependency has no API slice `component` is always `resolved` here. A `platform-resource` is too — once emitted — so only emit one whose `resourceType` is a `name` from this turn's `list_platform_resource_types`. An `org-service` resolves on catalog visibility, and is `blocked`/`access-required` when the provider exists but this project cannot see it. `needsSpec`, `specPath` and the other definition fields are gone from the component's schema — a draft carrying them fails the write-gate with a message naming the dependency file they moved to. ### Narrating the design turn The design-generate turn runs in the chat panel, so your turn text is what the user watches live. **Narrate each dependency decision in one plain-prose line as you settle it**, before moving to the next: - resolved → `✓ : using ` (say `, contract sliced` when you cut one, `, interface derived from docs` when you wrote it from the provider's reference, `, registered` for an org reuse) - needs-input → `: your choice — A / B / C are common; select a provider on its definition` - needs-contract → `: chosen, no published contract found — you can upload one or let me assume it, from the dependency's definition in the spec view` Never block the design on an unresolved dependency — print the line and keep emitting the rest; the user replies in the same chat to steer it, now or later. Then **close with three parts and nothing more**: one line per component (name, type, one-clause role); a **"Needs your input"** block listing ONLY the dependencies still unresolved, each as a LINK to its definition — `[currency-service](aep://spec/specs/design/dependencies/currency-service/dependency.json)` — followed by the single thing you need (the console opens the definition from the link; this link form is the one place a repo path is allowed in your prose); and a one-line pointer to `specs/design/`. The narration already carried the play-by-play, so a file-by-file recap would only bury the user's next action. Each **Needs your input** line names the dependency the way its definition in the spec view does, so the user can click through and press **Resolve** — that runs the `resolve-dependency` flow, which is where the contract gets provided or assumed; the design turn never waits for it. ### Resolving or reconsidering a named dependency on request `/resolve-dependency ` runs the `resolve-dependency` skill — the guided flow that takes one dependency from open to resolved; read that skill when the instruction names it. A plain chat turn may still point you at a dependency ("reconsider `stripe`"): read `specs/design/dependencies//dependency.json` from the snapshot and act on its current state. - **No service chosen — it carries `suggestions`, or nothing.** The user's answer, if the instruction carries one (a service name or a document URL), IS the choice: set `provider` + `style`, remove `suggestions`, and go for the contract (step 3). With no answer, put the choice to them — the suggestions, or what your research finds, each with a one-line distinction, plus that they may name another — and write nothing until they answer. - **Already resolved — reconsider.** This is the only branch that may leave a catalog row that still fills the role. Present fresh alternatives in the conversation, or repin to the Registered name the user picks, or start a **Project External resource** under a **new** name. Edit ONLY that dependency's file: re-emit the whole `dependency.json` (never a patch) with every field you are not changing carried over exactly. The components' references do not change. Never write or alter `assumed` — that is the user's record; the write-gate refuses it. ### Descriptions, and the per-component artifacts Every dependency carries a one-line `description`: what the target is and how this component uses it. Source it per kind — an `external`'s definition file carries what the system is (the consumption instructions when the name is a Registered External resource) and the component's reference why this component calls it; an `org-service`'s says the specific operations it calls from the discovered contract, or plainly that no contract was resolvable, never a guess; a `platform-resource`'s says what it stores. The console shows it in the dependency drawer and the coding agent relies on it to integrate correctly. One component per directory. Every `web-application` gets a `wireframes.dsl` (`wireframes` governs it); every `service` gets an `openapi.yaml` (`openapi-conventions` governs it), emitted after domain-model.md's ER model. Other kinds (scheduled tasks, workers, …) carry no extra artifact yet — capture their behaviour fully in `description` and `dependencies`.