Ekklesia/docs/architecture/platform-architecture.md

# Platform architecture

Ekklesia is a long-lived platform from which churches can compose many applications and user
experiences. It begins as a modular monolith so contracts can stabilize before distribution is
introduced.

> **Trust boundary.** Installed modules are trusted compiled code, not sandboxed plugins: a module
> runs arbitrary JavaScript in the API process and shares its PostgreSQL role. The layering
> described below is a correctness and ownership boundary, not hostile-code isolation. A module that
> ships its own UI ([ADR 0021](decisions/0021-modules-as-hostable-products.md)) is exactly as
> trusted as one that does not. See
> [Security model and deployment trust boundaries](../development/security.md).

## Dependency model

The arrows below mean "depends on." Presentation and composition depend on stable lower-level
contracts; infrastructure never learns individual feature names.

```text
Surface Builder configuration -> Surfaces -> public capability contracts
                                      ^
                                      |
                         HTTP/API and client contracts
                                      |
Feature Modules -> Module SDK / platform contracts <- Core implementations
```

The four ownership layers are:

1. **Core** orchestrates generic platform infrastructure: startup, identity, permissions,
   configuration, database connectivity, storage, events, jobs, module discovery, and lifecycle.
2. **Modules** own domain behavior, data schemas, resources, actions, routes, events, permissions,
   jobs — and, per [ADR 0021](decisions/0021-modules-as-hostable-products.md), their own UI, authored
   in React against `@ekklesia/module-ui-sdk`
   ([ADR 0022](decisions/0022-module-ui-authoring-and-host-contract.md)). A module
   is an independently versioned product, not only a backend capability. It does not own the
   containing application shell or any platform policy.
3. **Surfaces** own the presentation concerns a module does not: the containing application shell,
   layout, navigation, accessibility, interaction, branding, and client state — including the shell
   that hosts a module's own UI.
4. **Surface Builder** stores validated declarative composition. It selects capabilities and
   surface-owned renderers but contains neither executable code nor module business logic.

A module owns its own product experience. Calendar data, actions, permissions, and its own
management UI live in `modules/calendar`; the dashboard or public-website shell that hosts it —
navigation, theme, layout, and platform chrome — lives in a surface. The module supplies the screen
for its feature; the surface supplies the application around it.

Modules are flat peers. `video`, `livestream`, `announcements`, and `calendar` are independent
first-class modules with no parent/child relationship. A Dashboard may group them into folders such
as `Media` or `Sunday Production`, but those groups are presentation configuration an administrator
can reorganize, never module ownership and never a dependency. Genuine module and capability
dependencies remain the only way one module may require another.

## Stable seams

- Modules use public SDK ports and injected Core services, never undocumented Core internals.
- Modules do not import another module's schema or private code. Integrations use public service
  contracts, capabilities, events, or APIs.
- Surfaces consume API/client and capability contracts, never feature-module packages.
- Core discovers feature modules generically. It contains no feature-specific imports or
  conditional branches.
- Deployable apps are thin composition roots and do not become domain-logic owners.
- Generated bootstrap artifacts may connect discovered entry points at the application edge;
  they do not become manually maintained Core registries.

## Security invariants

- Authorization is enforced server-side.
- Secrets are isolated from public configuration and logs.
- Authentication tokens, private form content, prayer requests, and pastoral information are not
  logged.
- Sensitive actions are designed for auditability without copying sensitive content into audit
  records.
- Private objects use signed access and namespaced storage paths.
- Every network service starts from least-privilege and local-only development defaults.

## Current implementation status

Implemented now: the Phase 1 repository and infrastructure foundation plus public module contracts,
static versioned manifests, independent capability versions and dependency ranges, automatic
filesystem discovery, compiled server loading, runtime-definition verification, staged capability
registration, dependency-ordered startup and reverse shutdown, rollback, and a backend-only module
template. Optional compiled schema entrypoints now contribute validated, namespaced module-owned
Drizzle tables to a deterministic aggregate without connecting to a database. Optional module-owned
Drizzle migration directories now produce an atomic dependency-ordered offline inventory with
validated metadata, explicit destructive-change declarations, and exact SHA-256 checksums. Core can
now compare that inventory with its fixed PostgreSQL history table, produce a read-only plan, and
apply the complete pending batch under a session advisory lock and one transaction. Destructive
migrations require an exact externally supplied approval bound to module, identity, and checksum.
Hermetic integration coverage now exercises those contracts through the production adapter against
the pinned PostgreSQL container, including real DDL rollback and advisory-lock concurrency. The
Core-owned Doctor composes those existing services into a deterministic terminal readiness report:
static module, schema, and migration validation always run when their prerequisites succeed, while
PostgreSQL history planning runs only when configured. Schema inspection evaluates compiled schema
definition entrypoints, which the module contract requires to be side-effect-free; Doctor never
imports or starts module server entrypoints. It does not apply migrations or modify PostgreSQL, and
it honestly skips object storage because no production Core storage service exists yet.

Phase 4A added the Core identity foundation. Core owns a Better Auth-backed identity schema
(`ekklesia_core_user`, `ekklesia_core_session`, `ekklesia_core_account`,
`ekklesia_core_verification`) reachable only through Ekklesia-owned contracts and an explicit
Core-owned Better Auth construction boundary; modules never import Better Auth or receive a raw
database client. That schema ships as a first-class Core-owned migration source that reuses the
exact migration format, checksum rule, planner, and transactional runner Phase 3 already
established, ordered before module migrations in the same aggregate. See
[ADR 0010](decisions/0010-core-identity-and-better-auth-adoption.md).

Phase 4B adds identity HTTP transport: a minimal Hono-based `apps/api` composition root mounts
Better Auth at `/api/auth/*` and exposes one Ekklesia-owned route, `GET /api/v1/principal`, behind
Core's own Fetch-compatible identity runtime (`@ekklesia/core/identity`) — Core still does not
depend on Hono. Public email/password registration is the intended eventual product policy — every
account receives identical lowest-privilege baseline status, and signup order never grants
elevation — but is disabled by default as of Phase 5D pass 1, below. See
[ADR 0011](decisions/0011-identity-http-transport-and-public-enrollment.md) and
[the API guide](../development/api.md), and
[the identity development guide](../development/identity.md) for the underlying schema and
contracts. It is now possible to publicly register, sign in, resolve a principal, and sign out.

Phase 4C is complete: Core's authorization foundation — a schema, evaluator, and store for
platform owners, explicit grants, and relationship-derived grants, plus an immutable permission
registry — and an explicit, single-use, auditable platform-owner bootstrap command, plus reusable
Hono enforcement and an `/api/v1/grants` HTTP API in `apps/api`. See
[ADR 0013](decisions/0013-core-authorization-and-owner-bootstrap.md) and
[the authorization guide](../development/authorization.md).

Phase 5A wired module-declared permissions into that same authorization system — a version-3
manifest, one composed platform permission registry spanning Core's own declarations and every
installed module's, enforced through the identical middleware Core's own routes use. Phase 5B let a
module mount its own framework-neutral HTTP routes in production, under
`/api/v1/modules/<module-id>`, enforced and response-sanitized exactly like Core's own routes. Phase
5C added typed module database access (`context.services.database`) for a module's lifecycle hooks
and authorized HTTP handlers, over the platform's one existing PostgreSQL pool.
See [ADR 0014](decisions/0014-module-permission-declarations-and-platform-registry.md),
[ADR 0015](decisions/0015-static-module-http-routing-and-runtime-lifecycle.md),
[ADR 0016](decisions/0016-module-database-access.md), and the repository root
[README](../../README.md#current-status) for the complete, current status of every phase.

**Phase 5D is complete.** Five passes hardened the platform against an independent security audit of
the Phase 5C checkpoint, and an independent whole-repository re-audit closed the phase:

1. the public request perimeter — a server-owned client-address resolution boundary for the
   authentication rate limiter, public sign-up disabled by default behind an explicit typed opt-in,
   an enforced request-body ceiling on every public route (including a module route's own declared
   contract), and finite Node header/request timeouts;
2. identity session resolution, and a mandatory certificate- **and** hostname-verified PostgreSQL
   transport with no plaintext or `rejectUnauthorized: false` exception;
3. durable authorization history that survives user deletion, a one-time owner bootstrap that
   deleting a user cannot reopen, and bounded, unambiguous explicit-grant management;
4. module route-overlap rejection at registration, finite startup rollback and shutdown deadlines,
   and hardened migration command timeouts and SQL execution;
5. deployment and supply-chain closure plus the final re-audit.

See [ADR 0017](decisions/0017-public-request-perimeter-hardening.md),
[ADR 0018](decisions/0018-identity-session-resolution-and-database-transport.md),
[ADR 0019](decisions/0019-durable-authorization-history-and-grant-management.md), and
[ADR 0020](decisions/0020-module-runtime-and-migration-execution-hardening.md).

These guarantees hold under a **trusted-contributor, not-yet-deployed** threat model. The remaining
limitations are operational rather than architectural: CI is a trusted-code-only boundary whose
runner topology and job-token authority are unverified, and Ekklesia is not deployed, so the origin,
proxy, and throttling properties a public launch requires are unproven. Neither set of requirements
blocks Phase 6. Read
[Security model and deployment trust boundaries](../development/security.md) for what each boundary
does and does not protect against, and the repository root
[README](../../README.md#current-status) for the current status of every phase.

**Phase 6A established the module product contract.**
[ADR 0021](decisions/0021-modules-as-hostable-products.md) replaces the backend-only module model:
a module is an independently versioned product that may own its own UI, hostable inside Ekklesia and
— later, from the same implementation — as a standalone application. Core keeps the host shell and
every platform policy, the module graph stays flat, and Dashboard grouping stays presentation
configuration.

What that pass implemented is the **static contract only**: `manifestVersion: 4` adds one optional
`entrypoints.ui` field, validated during discovery exactly like the server and schema entrypoints —
package-relative, inside the package, compiled ESM. Discovery remains inert; nothing imports, mounts,
or renders that entrypoint.

**Phase 6B pass 1 defines the module UI authoring model and host contract.**
[ADR 0022](decisions/0022-module-ui-authoring-and-host-contract.md) selects React and TypeScript as
the supported way to author module UI, and defines what a compiled `entrypoints.ui` artifact exports
and what a host provides it. React is the authoring model but deliberately not the contract: an
artifact default-exports `defineModuleUi({ id, version, mount })`, and `mount(container, context)`
takes a DOM element and returns an unmount function, so a module's framework and a host's stay
independent.

The contract lives in `@ekklesia/module-ui-sdk`, a browser-safe shared package with no runtime
dependencies, consumed by module authors and hosts alike. Its host context is four members —
`moduleId`, `api`, `principal`, `permissions`. Module UI reaches its own backend through
`api.request(path)` with a path relative to the module's own API root, never by constructing
Ekklesia's `/api/v1/modules/<module-id>` prefix, which is what keeps a standalone host possible.
Client-side permission hints are presentation only; server-side enforcement remains the sole
authority. Module UI is trusted code in the host's browser realm — there is no sandbox, matching the
backend trust model rather than overstating it.

Core is untouched by this: discovery still validates the `entrypoints.ui` path and never evaluates
it, and hosts perform their own dynamic import.

**Phase 6B pass 2 makes that contract buildable.**
[ADR 0023](decisions/0023-module-ui-build-pipeline.md) selects esbuild, compiles a module's
`src/ui/index.tsx` into the browser ESM artifact its manifest declares, and puts every bundler
option in one `tooling` package so module authors write no build configuration. React is bundled
rather than externalized, keeping `mount()` the ABI and a module artifact hostable by any host;
styling is inline style objects only, and a stylesheet import fails the build rather than emitting an
asset nothing declares. Building remains an authoring step — Core never builds, and discovery still
only validates the artifact a module shipped. The Dashboard shell, a UI runtime, a design system, a
stylesheet loading contract, the standalone host, and every feature module remain future work.

**Phase 6B pass 3 makes the browser boundary real and adds the generic host loader.**
[ADR 0024](decisions/0024-browser-safe-ui-sdk-and-host-loader.md) removes the UI SDK's last
dependency — one type-only import of the contracts barrel that pulled Drizzle's types, and Node's
globals, into browser programs — so the SDK now depends on nothing and defines its own plain
`ModuleUiPrincipal`. `@ekklesia/module-ui-host` is the loader both Ekklesia and a future standalone
host will use: dynamic import from a browser URL, identity validated against the manifest before
mounting, a host-owned container the loader never mutates, and an idempotent unmount. Modules may not
depend on it.

**Phase 6C pass 1 publishes a validated module UI artifact at a browser URL.**
[ADR 0025](decisions/0025-trusted-module-ui-asset-publication.md) closes the gap the previous pass
named: Core resolves `entrypoints.ui` to a **server filesystem path**, and a browser needs a **URL**.

Core owns the policy and `apps/api` owns the transport. `createModuleUiPublicationRegistry`
(`core/src/modules/ui-publication.ts`) answers "may this be published, and which exact file is it?"
from the discovered, started module inventory — publishable means the module survived discovery
*and* declares `entrypoints.ui`, no new lifecycle state and no installer. `apps/api` serves
`GET /api/v1/module-ui/<module-id>/<version>`, where both segments are **lookup keys, not path
components**: an exact match yields the canonical artifact path discovery already validated, and no
request value is ever composed into a filesystem path. There is no wildcard segment, so traversal,
sibling chunks, package-root files, and source maps are unreachable by construction — an installed
module directory never becomes a static file root. The prefix is a sibling of `/api/v1/modules/`
rather than a child because `ui` is a legal module route segment and a module could otherwise collide
with the platform.

The route requires no authentication: the bundle confers no authority, every module API stays behind
`requirePermission`, and a cookie-gated route would break cross-origin `import()`, which sends none.
The disclosure that buys — a caller who knows a module id and its exact version can download that
bundle — is stated rather than papered over, and the three failure modes are made indistinguishable
so the route is not an enumeration oracle. Caching is `no-cache` with a strong `ETag`, not
`immutable`, because without an installer a version can be rebuilt with different bytes. The server
reads and writes bytes; it never imports, evaluates, or transforms the artifact.

**A host could now obtain a URL, and nothing uses one.** There is no Dashboard shell, no navigation,
no module metadata endpoint, and no code that calls the URL helper outside its own tests. A design
system, stylesheet and general asset publication, and the standalone host remain future work.
Restart-based discovery, explicit operator-invoked migrations, and the trusted compiled-module model
are all unchanged.

Target architecture not yet implemented includes production approval-provider
composition, physical storage-bucket provisioning, jobs/workflow automation, richer public resource
and action contracts, a Dashboard, a Builder, and reference feature modules; none of these are
scheduled by this document.