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Ekklesia/docs/architecture/repository-boundaries.md
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ekklesiaandClaude Opus 5 c444ff570b feat: let one module contribute a browser renderer to another's capability
The platform has had a complete story for one module using another's
*backend* since ADR 0006 — capabilities, versioned ranges, provider
registration. It has had none at all for one module using another's *browser*
code, and every workaround is wrong in a way that matters: a consumer cannot
import a peer module, it cannot re-implement a renderer for a domain it does
not own, and a second `entrypoints` role would put the platform in charge of
deciding when a slot inside someone else's screen should be filled.

Add a generic browser contribution. `manifestVersion: 7` declares one:
namespaced id, its own version, a target capability, a compatible range, and
one artifact. That is the complete list, and the omissions are the decision —
no payload schema, slot, ordering, or rendering hint exists anywhere, so Core
cannot learn what a slide is because the declaration cannot express it.

Discovery resolves a contribution artifact through the *identical* loop every
other compiled entrypoint uses, inheriting the path, containment, symlink,
extension, and file-kind checks rather than getting a weaker copy of them. The
registry publishes one only when another eligible module provides the target
capability within the declared range; otherwise it is absent rather than
mounted and broken. `apps/api` serves it as a sibling of the artifact and
display routes, with the same policy: three lookup keys, one exact match, one
already-validated path, and one indistinguishable 404 for unknown, undeclared,
stale, and incompatible alike.

A consumer discovers through the host, never through a URL. Its descriptor
carries identity, version, and capability; the URL stays server-side and is
resolved exactly as `api.request("records")` is. A module can only ever see
contributions aimed at a capability it itself provides, and cannot name its
way to anything else — a mount for a withheld id fails without fetching.

The consumer owns the domain contract entirely. Input is opaque JSON, checked
structurally so a Date, a function, a cycle, or `undefined` fails at the
boundary rather than vanishing somewhere far from the mistake, and checked for
nothing else. A contributed renderer receives its own id and that input: no
API client, realtime, principal, configuration, database, storage, or
credential. Loading one grants its module nothing.

The contribution ABI is versioned separately from the module UI ABI, because
the two have different shapes and lifecycles and coupling them would force
every module to rebuild whenever either moved. It supports asynchronous
readiness, update-without-remount (a screen that remounted per tick would
restart animations and reload media), deterministic cleanup in a `finally`,
and sanitized failure that never carries the consumer's domain data. Each
renderer mounts in its own isolated root with its own stylesheet.

The template now declares a contribution, so `pnpm build` exercises the whole
authoring path, and the shell suite drives the full relationship — one module
discovering, mounting, updating, and unmounting another's React renderer with
neither importing the other.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-08-27 07:47:10 -05:00

13 KiB

Repository boundaries

These rules map platform ownership to filesystem and package boundaries. The executable check is pnpm boundaries; CI must reject violations.

Area Owns May depend on
apps/* Thin deployable composition roots Public Core APIs, generated bootstrap, or a surface as required by the app
core Feature-agnostic platform implementations Public contracts and external infrastructure libraries
modules/* Domain capability, data, and the module's own UI Module SDK, module UI SDK, the approved design packages, public contracts, React, and external backend libraries
surfaces/* The application shell, UI, renderers, navigation, and interaction Surface SDK, API/auth clients, the module UI SDK and host loader, design packages, and a browser framework
builders/* Declarative surface composition tooling Builder/surface SDKs and public contracts
packages/* Explicitly scoped SDKs, contracts, clients, design, testing, or tooling Only dependencies appropriate to the package's declared level
templates/module A small example backend module The same dependencies allowed for any module

Mandatory rules

  • Core never imports a feature module, surface, Builder implementation, or app.
  • A module never imports Core implementations, another module, a surface, Builder code, or an app.
  • A module may own UI (ADR 0021) and authors it in React and TypeScript (ADR 0022). A module may therefore contain .tsx source and depend on react, react-dom, and @ekklesia/module-ui-sdk. Since ADR 0040 it may also contain plain .css, but only inside a browser-artifact source root the canonical builder compiles (src/ui/, src/display/, src/contributions/); a stylesheet anywhere else in a module is a file no build reads and no host loads. It still cannot contain .jsx, other stylesheet dialects, single-file components, Astro/Marko/MDX/HTML views, or SVG presentation assets, and cannot depend on any other UI framework (including react-router-dom, react-native, and @vitejs/plugin-react) or on any shared role beyond the two approved design packages named below. A module needs no bundler plugin: @ekklesia/module-ui-build — a tooling package, a role modules could already depend on — owns the entire module UI build (ADR 0023). An unsupported framework aliased behind an allowed name is resolved and rejected by its real target.
  • Module UI source is subject to the identical layer rules as module backend source: it may not import Core, an app, a surface, a builder, or another module. It also may not import @ekklesia/module-ui-host: that package is host infrastructure, and a module bundling the loader would blur the author/host split (ADR 0024).
  • A module may consume exactly two shared design roles: design-tokens (@ekklesia/design-tokens) and ui (@ekklesia/ui), added by ADR 0039. This is a named allowlist, not a general "browser-safe shared packages are fine" relaxation: api-client, auth-client, surface-sdk, and module-ui-host remain rejected inside a module. Both approved packages are browser-safe by construction — design-tokens has no dependencies at all and ui depends only on it — so a module UI file that imports them still cannot typecheck process.env, proven by a real compile under the exact browser project a module uses. Both are also pinned at the bottom of the presentation stack by design-packages-depend-downward-only: neither may reach an implementation layer, an API/auth client, or the backend contracts barrel, because a design package that could would put all of it inside every module artifact that renders a button.
  • A module references registered global semantic tokens and may derive private, differently-prefixed aliases from them inside its own artifact. It may never define an --ekklesia-* custom property: that would invent a global theme variable outside the registry, which a future theme editor could not enumerate and another module could unknowingly depend on.
  • @ekklesia/module-ui-sdk has no dependencies at all, and @ekklesia/module-ui-host depends only on it. Both are browser-safe by construction: neither can pull a backend type graph — and with it Node's global declarations — into browser code. Core still owns the containing application shell and all platform policy, and module UI reaches the host only through @ekklesia/module-ui-sdk.
  • A module stylesheet is compiled into the one declared JavaScript artifact as text and installed by the host at mount; there is no sidecar file, no second publication route, and no manifest field for one. Every browser artifact is mounted inside its own Shadow DOM root the generic loader creates, so one module's styles cannot reach the Dashboard, another module, or another renderer, and the host's cannot reach in. That root is a correctness boundary for styles, never a sandbox: module code remains trusted, same-realm code. The browser mount ABI is versioned (MODULE_UI_ABI_VERSION) and a mismatched artifact fails closed rather than mounting under guessed semantics.
  • A module may declare browser contributions (manifest.contributions, v7): compiled renderers it offers to capabilities other modules provide (ADR 0041). Core validates identity, compatibility, and the artifact path through the identical resolution every other compiled entrypoint uses, and knows nothing about what a contribution renders — there is no payload schema, slot, ordering, or rendering hint anywhere in the platform. A contribution is published only when another eligible module provides its target capability within the declared range; otherwise it is absent rather than broken. A consuming module discovers contributions through ModuleUiHostContext.contributions and mounts them by id; it never constructs a publication URL, and it can only ever see contributions aimed at a capability it itself provides. A contributed renderer receives its own id and the consumer's opaque JSON input, and no database, storage, credential, session, or API client of its own.
  • Manifest v7 permits independently optional primary (entrypoints.ui) and full-viewport display (entrypoints.display) artifacts. Modules own both feature experiences; surfaces own their containers, routes, navigation/chrome, credentials, error states, and publication wiring. The fixed authoring sources are src/ui/index.tsx and src/display/index.tsx; both use the same role-neutral UI SDK ABI and neither may import a surface or host loader.
  • Module UI asset publication runs Core → apps/api, never the other way (ADR 0025). Core owns the policy (createModuleUiPublicationRegistry, built only from already-validated DiscoveredModule records); apps/api owns the HTTP route and the one canonical URL construction. Neither @ekklesia/module-ui-host nor @ekklesia/module-ui-sdk learns anything about how Ekklesia publishes artifacts — the loader takes a URL and stays host-neutral — and no module may reach publication internals. This introduced no new package and no boundary relaxation: apps/* could already depend on Core and on shared packages.
  • A publication helper accepts module identity only. Neither Core's registry nor the API's URL builder takes a filename, relative path, or any other artifact selector, so no caller can use one to reach a second file inside a module package.
  • A surface never imports Core or a feature module. It uses public API/client contracts, and reaches the server over HTTP.
  • A surface may depend only on browser-safe shared roles (api-client, auth-client, design-tokens, module-ui-host, module-ui-sdk, surface-sdk, ui) plus dev-time testing and tooling. @ekklesia/contracts is deliberately excluded, despite being a "public contract" package: its barrel pulls Drizzle's types, and with them Node's global declarations, into any program that imports it — measured in ADR 0024, which removed exactly that import from @ekklesia/module-ui-sdk to close the browser boundary. module-sdk re-exports the same barrel and is excluded for the same reason. A surface declares its own types for the wire and validates what arrives (ADR 0026).
  • Dashboard navigation configuration is Core-owned platform state, never module-owned: Core stores groups and placements and resolves the view, apps/api exposes it, and surfaces/shell renders it. A group is presentation configuration and never module structure — it has no manifest, version, artifact, or lifecycle, and nothing in discovery, dependency resolution, or module startup may ever read it (ADR 0027). A module's manifest declares its own display name and nothing about where it is presented.
  • The browser host (surfaces/shell) statically imports no module. Every installed module UI it can mount arrives at run time as a URL from the module UI inventory, is fetched by the generic loader, and is never bundled into the shell. Its own build (esbuild, owned by that package) is a separate concern from @ekklesia/module-ui-build, which compiles a module's declared artifact.
  • Dashboard login, logout, and session-transition UX are surface-owned (ADR 0034). They use the API over HTTP and must not add credentials, cookies, tokens, or auth methods to ModuleUiHostContext; modules keep receiving only the host-neutral principal and permission hints already in the UI SDK.
  • The display browser application is a separate surface entrypoint under surfaces/shell; it also statically imports no module and mounts only the exact display descriptor/artifact supplied by the API. It contains no Dashboard chrome and does not move display rendering into the surface—the module still owns that renderer.
  • Separate surfaces do not import each other's internals.
  • Builder code composes contracts and surface renderer identifiers; it does not import module or surface internals.
  • Contract and SDK packages cannot depend upward on implementations.
  • Workspace package consumers use declared exports, not private subpaths.
  • Every internal dependency uses a workspace: range and every imported workspace package is declared by the consumer.
  • Workspace aliases are forbidden because they obscure package ownership in the dependency graph.
  • Workspace package names are unique and shared packages declare a recognized architectural role.
  • Circular source and workspace-package dependencies are rejected.
  • Cross-module data access uses services, events, capabilities, or opaque identifiers rather than direct table imports and foreign keys. Modules may not import another module's Drizzle tables, columns, relations, schema entrypoint, or migration internals.

The design packages are covered the same way: one fixture proves a module may depend on both, one proves every other shared role stays rejected, and one proves neither design package may depend upward.

The boundary test suite includes intentionally invalid fixture graphs. This proves that the guard rejects every currently machine-checkable repository rule even before production packages fill every directory. The UI guard rejects component, view, template, stylesheet, shared UI-role, and common UI-framework dependencies inside modules. This deny list is defense in depth; package review remains required when adopting a new frontend technology. ADR 0022 narrowed the guard precisely rather than removing it: React was un-denied, every other framework stayed denied, and the layer rules were untouched.

The Phase 3 schema validator complements source boundaries by checking table ownership, foreign-key targets, and physical table namespaces in compiled Drizzle metadata. Offline migration validation checks each module's packaged Drizzle inventory and policy contract, while deliberately making no claim that opaque SQL ownership can be proven without PostgreSQL-aware analysis.

Generated code

Generated artifacts are reproducible outputs with a named generator and validation step. A generated module bootstrap under the root generated/ boundary may import discovered module entry points, and apps may import that generated bootstrap. Handwritten app and Core code still cannot import feature modules directly. Generated files are never an excuse for a hand-maintained central module registry.