feat: give display devices their own paired identity

ADR 0033 gave Ekklesia a display host and ADR 0034 gave it a login page.
Together, the only way to light a television in a foyer was to sign a
human being into it and leave that session running on a screen anyone can
walk up to: a person's credentials on a wall, a person's session as the
thing signage depends on, and the display going dark when they are
revoked or their session simply expires.

A screen is not a person. Ekklesia now recognizes three principal classes
— anonymous, authenticated human, and managed device — and a device is a
first-class principal with its own credential and its own explicit
permissions. It has no email, no password, and no row in the identity
tables, and it satisfies the `authenticated` baseline never, so every
route that settles for "somebody is signed in" stays closed to it.

Device permissions live in their own table because
ekklesia_core_grant.user_id is a non-null foreign key into the user table
and making it polymorphic would rewrite the platform's central
authorization record to serve one narrow case. That is a schema decision,
not a second decision point: the evaluator gained one branch, so a device
is allowed or denied by the same function, with the same deny-by-default,
as anyone else — with no owner path it could reach and no baseline that
stands in for a grant.

The six-digit code is not the credential. It is printed across a screen in
a public hallway, so it is treated as public: it identifies a request to
an administrator and is worth nothing alone. Collecting the credential
also requires a 256-bit claim secret held only in the requesting browser's
HttpOnly cookie, and approving requires the restricted core.devices.manage
permission. Without that split, reading a code off a wall would hand over
the screen's identity.

The permission a pairing asks for is read from the module's validated
display declaration, never from the request, so a browser cannot ask to be
granted core.devices.manage or another module's permission. Approval
grants exactly that one permission.

Credentials are stored only as SHA-256; the raw value exists in the
Set-Cookie that issues it and the device's own cookie jar, and is never
logged, returned in JSON, or placed in a URL. The cookie is HttpOnly, so
the module display code running in that same page cannot read it.
Revocation is a server-side column checked on every principal resolution,
and re-pairing mints a new identity so an old credential can never come
back. State transitions are conditional updates, so one code cannot be
approved twice or claimed into two credentials under a race.

/api/v1/principal still reports a device as anonymous: it is what the
Dashboard uses to decide whether a person is signed in. Displays read
their viewer from the descriptor instead, which already performed the
authorization — so displays are descriptor-first while the Dashboard stays
principal-first, and neither infers an identity by elimination.

Proven end to end against real PostgreSQL and real HTTP: an unpaired
screen shows a code, an owner approves it, the device opens the display
descriptor and a realtime stream, and revocation closes both while the
device still holds its cookie. An already-open SSE stream is bounded by
realtime's existing five-minute reconnect rather than closed instantly,
and that bound is documented rather than called immediate.

Co-Authored-By: Claude Opus 5 <[email protected]>

docs/development/api.md

@@ -826,6 +826,43 @@ still the right choice when the response must be computed, transformed, or autho
 There are no signed **write** URLs: uploads go through a module route, where the module can validate
 what it is accepting.
 
+## Display device pairing and management
+
+Host-owned, and reachable by no module
+([ADR 0036](../architecture/decisions/0036-managed-device-identity-and-pairing.md)). Two sibling
+prefixes: `/api/v1/device-pairing` and `/api/v1/devices`.
+
+**The screen's side** (no identity required; authority is the HttpOnly claim cookie the first call
+sets, never the code):
+
+| route | purpose |
+| --- | --- |
+| `POST /api/v1/device-pairing/requests` | Body `{moduleId}`. Returns `{code, expiresAt, pollIntervalMs}` and sets `ekklesia_device_pairing`. The permission is read from that module's validated display declaration — a request cannot name one. |
+| `POST /api/v1/device-pairing/claims` | Polls. Returns `{status}`; on `paired` it sets `ekklesia_device_session` and clears the pairing cookie. |
+
+**The administrator's side** (requires the restricted `core.devices.manage` and an exact trusted
+`Origin`):
+
+| route | purpose |
+| --- | --- |
+| `POST /api/v1/device-pairing/lookups` | Body `{code}`. Shows the module and permission a screen is asking for, before approving. |
+| `POST /api/v1/device-pairing/approvals` | Body `{code, deviceName}`. The administrator names the screen; the screen never names itself. |
+| `GET /api/v1/devices` | Paired devices: name, permissions, created, last seen, revoked. Never a credential. |
+| `POST /api/v1/devices/:deviceId/revoke` | `204`. Server-side revocation, checked on every principal resolution. |
+
+The pairing code travels in request **bodies**, never a path or query, so it does not land in access
+logs, browser history, or a `Referer`. Expired, consumed, mistyped, and never-existed codes all
+answer the same way.
+
+`/api/v1/principal` deliberately reports a device as `anonymous`: it answers a question about
+*people*, and the Dashboard depends on that. A display reads its viewer from the display descriptor
+instead, which now carries `viewer: {kind: "authenticated", userId} | {kind: "device", deviceId}`.
+
+**Cookies.** `ekklesia_device_session` is `HttpOnly`, `SameSite=Strict`, host-only, `Path=/`, and
+`Secure` when the identity base URL is https. Deployment note: because it is host-only and
+`SameSite=Strict`, a display must be served from the same origin as the API — which the platform's
+own `/display/<module-id>` route is.
+
 ## Module HTTP routes
 
 An installed module's routes (declared via `http.route(...)` in its `register` hook — see

docs/development/authorization.md

@@ -275,6 +275,30 @@ unregistered target permission instead receives the identical sanitized
 `403 {"code":"AUTHORIZATION_DENIED"}` a genuinely denied caller would, so that response never
 reveals whether the caller was denied or the permission was simply never registered.
 
+## Device permissions
+
+A paired display device holds explicit permissions of its own, in `ekklesia_core_device_permission`
+rather than in `ekklesia_core_grant`
+([ADR 0036](../architecture/decisions/0036-managed-device-identity-and-pairing.md)). That table's
+`user_id` is a non-null foreign key into the user table, and making it polymorphic would rewrite the
+platform's central authorization record to serve one narrow case.
+
+**It is a separate table, not a separate decision.** `createAuthorizationEvaluator` consults exactly
+one authority per call, chosen by principal kind, and a device reaches `allowed` only by holding the
+exact permission being checked:
+
+- `public` — allowed, as for any principal.
+- `authenticated` — **denied**, always. A device is not a person.
+- `restricted` — allowed only with an active, unrevoked permission for that exact device.
+
+A device is never a platform owner, and the owner and user-grant ports are not consulted for one at
+all. A deployment that composed no device support denies every device. Revoking a device revokes its
+permissions with it, and the permission lookup joins the device row so a revoked device has no
+permissions even if a row were left behind.
+
+Approving a pairing grants exactly the one display permission the host derived from the module's
+validated display declaration — never a bundle, never a permission the browser named.
+
 ## Platform-owner bootstrap
 
 There is no "first user becomes owner" inference anywhere in this repository, and no HTTP

docs/development/identity.md

@@ -265,6 +265,20 @@ registry) is covered separately in [Authorization](authorization.md). Its bootst
 an existing identity; it does not create one. Creating the *first* identity on a fresh installation
 is what `pnpm identity:create-initial-owner` is for — see below.
 
+## Three principal classes
+
+Ekklesia recognizes **anonymous**, **authenticated** (a person), and **device** (a paired display)
+([ADR 0036](../architecture/decisions/0036-managed-device-identity-and-pairing.md)).
+
+A device is not a user: it has no row in the identity tables, no email, no password, and no human
+session. `isAuthenticatedPrincipal` returns `false` for it, which is what keeps every "somebody is
+signed in" route closed to a screen on a wall. Its credential is a separate HttpOnly cookie
+(`ekklesia_device_session`), resolved after Better Auth has been asked first — a human session always
+wins, so a browser holding both remains a person.
+
+`/api/v1/principal` reports a device as `anonymous` on purpose. It is the endpoint the Dashboard uses
+to decide whether a person is signed in, and a device is not one.
+
 ## Creating the first platform owner
 
 A fresh installation has a login page and nothing to log in to. Public registration is disabled by

docs/development/security.md

@@ -544,6 +544,44 @@ is **where it can be invoked**, not a weaker policy:
 It deliberately does not solve creating *additional* users or owners. That is user administration,
 which does not exist yet.
 
+### A display device is a principal, not a person and not a shortcut
+
+An unattended screen has its own identity, paired by an administrator and revocable by one
+([ADR 0036](../architecture/decisions/0036-managed-device-identity-and-pairing.md)). What makes that
+safe is what it is *not* allowed to be:
+
+- **Not a user.** No device row exists in the identity tables and no device has an email or a
+  password. A device satisfies the `authenticated` baseline **never**, so every route that settles
+  for "somebody is signed in" stays closed to a television.
+- **Not a bypass.** Device authority is decided by the same `createAuthorizationEvaluator` as
+  everyone else's, with the same deny-by-default. There is no device branch that returns allowed
+  before consulting an explicit permission, and no device is ever a platform owner.
+- **Not broadly granted.** Approval grants exactly the one display permission the host derived from
+  the module's own validated display declaration. A browser cannot ask for a permission of its
+  choosing, and a device paired for one display has no authority over another.
+- **Not a Dashboard login.** `/api/v1/principal` reports a device as anonymous, and the shell tests
+  for `=== "authenticated"` rather than "not anonymous". A device cookie cannot open the Dashboard.
+- **Not the pairing code.** The six-digit code is displayed on a wall and is treated as public. It
+  identifies a request to an administrator; it never yields a credential. Collecting the credential
+  additionally requires the HttpOnly claim cookie only the requesting browser holds, so reading a
+  code off a screen is worth nothing.
+- **Not stored in a usable form.** The server keeps SHA-256 of the credential. The raw value exists
+  only in the `Set-Cookie` that issues it and in the device's own cookie jar; it is never logged, put
+  in a query string, returned in JSON, or written to `localStorage`. The cookie is `HttpOnly`, so the
+  module display code running in that very page cannot read it.
+- **Not revocable only at the browser.** Revocation is a server-side column checked on every
+  principal resolution. A revoked screen keeps its cookie and stops working; re-pairing creates a
+  **new** identity, so an old credential can never be reactivated.
+
+Approval, listing, and revocation require the restricted `core.devices.manage` permission and an
+exact trusted `Origin`, exactly like every other Core mutation. A device cannot approve a pairing —
+including its own.
+
+**Bounded, not instantaneous.** A revoked device fails its next request and its next realtime
+connection immediately, but an already-open SSE stream is not torn down at that moment: realtime's
+five-minute forced reconnect is the upper bound on how long a just-revoked screen can keep receiving
+a channel. That window is stated rather than described as instant.
+
 ### Rate limiting is per-process today
 
 Better Auth's authentication rate limiter is **in-memory and per API process**. That is acceptable

docs/development/testing.md

@@ -351,6 +351,30 @@ password arriving on standard input and never in `argv`, `--password` refused, a
 `DATABASE_URL`, and an unmigrated database refused rather than silently migrated — with assertions
 that neither stdout nor stderr contains the password or the connection string.
 
+A further suite (`apps/api/tests/device-pairing.integration.ts`, same harness) proves display device
+pairing end to end against real PostgreSQL and the real HTTP transport
+([ADR 0036](../architecture/decisions/0036-managed-device-identity-and-pairing.md)). None of it is
+mocked: a screen with no identity is refused the descriptor but served the page it needs, asks to be
+paired, and receives a code; a real platform owner — created by the Pass 1B bootstrap and signed in
+through the real login transport — looks the code up and approves it by name; the screen collects its
+credential from a real `Set-Cookie` and then opens the real display descriptor and a real realtime
+stream; and the owner revokes it, after which both fail while the device still holds its cookie.
+
+The suite also pins the properties that make the design safe rather than merely working: that the
+raw credential appears nowhere in the database or in any response body, that the permission is taken
+from the display declaration and not from a request that tried to name `core.devices.manage`, that
+someone who knows only the code (an onlooker reading a television) is issued nothing, that anonymous
+callers, a paired device, and a cross-origin administrator are all refused approval, that one code
+cannot be approved twice or claimed into two credentials under a race, that re-pairing produces a
+fresh identity while the old credential stays dead, and that a browser holding both a human session
+and a device cookie remains a person.
+
+Device authority itself is proven without a database in `core/tests/authorization-device.test.ts`,
+which is mostly a list of things a device must *not* acquire: authority from being a principal, from
+an `authenticated` baseline, from platform ownership, or from a user grant. Its ports are wired to
+answer "yes" to every human question, so any accidental fall-through into a human path would flip
+those assertions.
+
 ### Which kind of timing proof lives where
 
 Pass 4 introduced several deadlines, and their tests deliberately differ in kind: