feat: close the browser boundary and add the generic UI host loader #18
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Reference: Zayin/Ekklesia#18
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Two gaps stood between the module UI contract and a host that could use
it. ADR 0023 recorded the first honestly but never diagnosed it: a module
UI file compiled with
"types": []could still typecheckprocess.env.The second was simply missing — nothing imported a compiled artifact,
checked its identity, mounted it, or tore it down.
The leak was one type-only import, bisected against the real type graph
rather than guessed.
@ekklesia/module-ui-sdkimportedtype { EkklesiaPrincipal } from "@ekklesia/contracts". Importingcontracts/identity alone is clean and importing Zod alone is clean, but
contracts exposes a single barrel entry, so that one import reached
module-database, whose Drizzle types re-introduce Node's globals. The
runtime was never affected — the import was erased and host-context.js is
export {}— but a type-graph leak is still a real boundary failure,because it silently permits code that cannot run in its target
environment.
The fix is not a narrower import path. The SDK now has no dependencies at
all, so there is no graph to leak through and no future contracts change
can reopen this. It owns
ModuleUiPrincipal: the same shape ADR 0022chose, with the Zod brand dropped. That brand encodes a server-side
parsing guarantee a browser cannot produce, and it is the same reason
permissions.hasalready took a plain string. An Ekklesia host stillpasses its own
EkklesiaPrincipalstraight through — a branded string isassignable to
string— while a standalone host builds the literal.Proven the way an author experiences it: two fixtures compiled under the
exact project a module uses, one supported and one deliberately reaching
for
process, with the second required to fail on that specific name.@ekklesia/module-ui-hostis the generic loader, in its own packagebecause the SDK is bundled into every module artifact and host-only
loader code has no business shipping there. The boundary checker enforces
both directions: modules may not depend on the loader, and the loader may
depend only on the SDK plus dev-time tooling.
The distinction that shaped the design: Core resolves
entrypoints.uitoan absolute path on the server's disk, and a browser needs a URL. A
loader that accepted the path would test green on a server and fail in
every real host, and would quietly own asset publication. So the loader
takes a browser-loadable URL and knows nothing about how one is obtained.
Ekklesia has no route that publishes installed artifacts, so this is
precisely: loader complete, publication deferred. Nothing can mount an
installed module UI yet, and the docs say so rather than implying
otherwise.
Dynamic import is
(url) => import(url)with a non-analyzable specifier,kept as a runtime import so a host does not statically bundle every
installed module or need a hardcoded registry. It is injectable for
bundlers needing their own escape hatch, and deliberately not
evalornew Function, which would cost a hostunsafe-evalin its CSP.Identity is validated through the SDK's existing parser before
mountruns, so a stale or mismatched bundle never renders. Contract violations
propagate unwrapped; the loader adds only import and mount failure codes,
sanitized, with the cause attached. Unmount is idempotent, safe when a
module returned no cleanup, and marks an instance unmounted before
running cleanup so a throwing cleanup surfaces once and never re-runs. A
failed mount registers no cleanup. Each instance owns its own state, so
two mounts coexist. The loader never mutates the host's container — not
on success, failure, or unmount.
Tests prove all of it against real module URLs (
data:, which bothbrowsers and Node import natively) rather than filesystem paths,
including one artifact built by the canonical Pass 2 pipeline and run
under both an Ekklesia-shaped and a standalone-shaped context. Core,
apps/api, and the contracts package are untouched; discovery remains
inert.
Co-Authored-By: Claude Opus 5 [email protected]
Two gaps stood between the module UI contract and a host that could use it. ADR 0023 recorded the first honestly but never diagnosed it: a module UI file compiled with `"types": []` could still typecheck `process.env`. The second was simply missing — nothing imported a compiled artifact, checked its identity, mounted it, or tore it down. The leak was one type-only import, bisected against the real type graph rather than guessed. `@ekklesia/module-ui-sdk` imported `type { EkklesiaPrincipal } from "@ekklesia/contracts"`. Importing contracts/identity alone is clean and importing Zod alone is clean, but contracts exposes a single barrel entry, so that one import reached module-database, whose Drizzle types re-introduce Node's globals. The runtime was never affected — the import was erased and host-context.js is `export {}` — but a type-graph leak is still a real boundary failure, because it silently permits code that cannot run in its target environment. The fix is not a narrower import path. The SDK now has no dependencies at all, so there is no graph to leak through and no future contracts change can reopen this. It owns `ModuleUiPrincipal`: the same shape ADR 0022 chose, with the Zod brand dropped. That brand encodes a server-side parsing guarantee a browser cannot produce, and it is the same reason `permissions.has` already took a plain string. An Ekklesia host still passes its own `EkklesiaPrincipal` straight through — a branded string is assignable to `string` — while a standalone host builds the literal. Proven the way an author experiences it: two fixtures compiled under the exact project a module uses, one supported and one deliberately reaching for `process`, with the second required to fail on that specific name. `@ekklesia/module-ui-host` is the generic loader, in its own package because the SDK is bundled into every module artifact and host-only loader code has no business shipping there. The boundary checker enforces both directions: modules may not depend on the loader, and the loader may depend only on the SDK plus dev-time tooling. The distinction that shaped the design: Core resolves `entrypoints.ui` to an absolute path on the server's disk, and a browser needs a URL. A loader that accepted the path would test green on a server and fail in every real host, and would quietly own asset publication. So the loader takes a browser-loadable URL and knows nothing about how one is obtained. Ekklesia has no route that publishes installed artifacts, so this is precisely: loader complete, publication deferred. Nothing can mount an installed module UI yet, and the docs say so rather than implying otherwise. Dynamic import is `(url) => import(url)` with a non-analyzable specifier, kept as a runtime import so a host does not statically bundle every installed module or need a hardcoded registry. It is injectable for bundlers needing their own escape hatch, and deliberately not `eval` or `new Function`, which would cost a host `unsafe-eval` in its CSP. Identity is validated through the SDK's existing parser before `mount` runs, so a stale or mismatched bundle never renders. Contract violations propagate unwrapped; the loader adds only import and mount failure codes, sanitized, with the cause attached. Unmount is idempotent, safe when a module returned no cleanup, and marks an instance unmounted before running cleanup so a throwing cleanup surfaces once and never re-runs. A failed mount registers no cleanup. Each instance owns its own state, so two mounts coexist. The loader never mutates the host's container — not on success, failure, or unmount. Tests prove all of it against real module URLs (`data:`, which both browsers and Node import natively) rather than filesystem paths, including one artifact built by the canonical Pass 2 pipeline and run under both an Ekklesia-shaped and a standalone-shaped context. Core, apps/api, and the contracts package are untouched; discovery remains inert. Co-Authored-By: Claude Opus 5 <[email protected]>