# OIDC browser-client registration — informed-decision approver surface

**Workplan task:** `INFD-WP-0001-T07`
**For:** `key-cape` (`KEY-WP-0013-T02`, `KEY-WP-0013-T05`)
**Status:** **draft — not yet submitted.** One input outstanding: the deployed
origin (§2). Everything else is fixed and stable.
**Rulings:** `GH-DEC-2026-012`, `GH-DEC-2026-013`
**Contracts cited:** `key-cape/docs/approval-engine-auth-contract.md`,
`key-cape/docs/tenant-claim-contract.md`,
`approval-engine/docs/approver-surface-requirements.md`

---

## 1. What this closes

On 2026-09-08 `key-cape` asked `approval-engine` for the human approver client's
`client_id` and full callback URI. `approval-engine` correctly declined to
invent them: it is a bearer-token resource server with no Ingress, no redirect
endpoint, and no browser client. It recorded that the two strings belong to
whichever browser-facing approver UI presents `approval:approve` tokens to it.

That component is this repository. These are the two strings.

---

## 2. The two strings

| Field | Value |
| --- | --- |
| `client_id` | `informed-decision-approver` |
| Redirect URI | `https://decisions.coulomb.social/auth/callback` |

**`client_id` is fixed and stable.** It will not change.

**The origin is settled.** 2026-09-10: the operator assigned
`decisions.coulomb.social` to this surface. It is not the
`decide.coulomb.social` this document proposed — the assigned name is the one
that counts, and it is recorded here rather than the proposal, because
redirects match exactly at `/authorize` and a near-miss fails closed. That
exactness is why `approval-engine` refused to guess in the first place, and it
is the reason the proposed name is corrected here before submission rather
than reconciled afterwards.

- **Assigned:** `decisions.coulomb.social`, giving
  `https://decisions.coulomb.social/auth/callback`.
- **Consistent with** the estate's existing pattern (`forgejo.coulomb.social`,
  `hub.coulomb.social`, `kc.coulomb.social`), Traefik `ingressClassName`, TLS
  secret per host.
- **DNS resolves** to the cluster address as of 2026-09-10.
- **Still requires, in `railiance-apps` rather than here:** an Ingress manifest
  and an issued certificate. Manifest written 2026-09-10
  (`manifests/informed-decision-ingress.yaml`); not yet applied.

**The host answers. This document is ready to submit.** 2026-09-10 14:32 UTC:
`railiance-apps` applied the Ingress and cert-manager issued a Let's Encrypt
certificate for `decisions.coulomb.social`;
`GET https://decisions.coulomb.social/auth/callback` returns `200` over a
verified chain. The condition this document set for its own submission —
that the origin be real rather than plausible — is met. The path component
`/auth/callback` was fixed ahead of the host, so nothing else in this
registration moved.

The path is currently served by a placeholder while
`INFD-WP-0001-T08` is built. That does not affect the registration: `key-cape`
matches the redirect URI as a string at `/authorize` and never fetches it.

---

## 3. Client shape

| Property | Value |
| --- | --- |
| Grant | Authorization code |
| PKCE | Required, `S256` |
| Client type | Public |
| Redirect matching | Exact |
| Scopes | `openid`, `approval:read`, `approval:approve` |
| `mfaRequired` | `true` |

**`approval:read` is required and was missing from the original specification.**
Without it this surface could submit an approval entry it was never able to
display — raised by `approval-engine`, confirmed by `key-cape`, now in their
published contract.

**`approval:consume` is never requested.** `approval-engine` refuses it for human
principals, and consumption belongs to the PEP that causes the side effect
(`GH-DEC-2026-003`).

---

## 4. Expected access token

Verified by `approval-engine` (RS256 against the issuer's `/jwks`):

| Claim | Value |
| --- | --- |
| `aud` | `approval-engine` — the resource server, never the OAuth client id |
| `tenant` | `tenant:platform` — **exact** string equality, no alias or prefix handling |
| `principal_type` | `human` |
| `sub` | non-empty; becomes the approver identity in the entry |
| `scope` | non-empty, containing the exact scope for the route |
| `assurance` | a non-null JSON object — shape below |
| `iss`, `exp`, `iat` | verified, 30s leeway |

The **access** token is the evidence. `id_token` is never presented to
`approval-engine` and appears nowhere in that codebase.

### `assurance`

The shape is **`key-cape`'s**, defined in their
`docs/approval-engine-auth-contract.md` — `level` (`aal1|aal2`), `methods`,
`mfa`, `source`, `at`. **Cited here rather than restated, so it cannot drift.**

Two properties matter to this surface and are recorded rather than assumed:

- `at` is the **authentication** time, not the token mint time. `key-cape` fixed
  a defect here on 2026-09-09; the two differ by hours when a browser session is
  reused, and `approval-engine` stores this object verbatim as the only
  downstream record that MFA happened. Freshness is judged by comparing `at`,
  never by assuming it.
- `key-cape` emits `assurance` on every human token and never empty. This
  surface nevertheless requires the object to carry authentication facts rather
  than relying on it always arriving populated — `approval-engine` *accepts* an
  empty object, so an empty one would produce an entry evidencing nothing.

---

## 5. Tenant provenance — declared, not assumed

**This registration declares a tenant the directory record does not carry, and
says so here rather than letting it read as a directory-asserted fact.**

`GH-DEC-2026-013` ruled directory-sourced tenancy the terminal state and granted
`key-cape`'s registration-bound shape (`329e48f`) as a **declared bounded gap** —
admissible because its distinguishing case fails closed: registration and
directory disagreeing refuses issuance with `403 tenant_binding` rather than
relabelling.

Nothing populates `domain.User.Tenant` for approver users. So a registration
declaring `tenant:platform` reaches the token by the **gap route by
construction**, not by accident. Gate House was explicit: do not declare a tenant
the directory does not carry unless prepared to say so in the record.

Consequences accepted here:

1. **This is transitional.** When the directory carries tenants, the same
   `key-cape` code stops supplying and starts enforcing agreement, with no second
   migration. This registration is expected to survive that unchanged.
2. **The claim is stored with its provenance.** `key-cape` emits `tenant` as a
   bare string, so a consumer cannot distinguish a directory-asserted tenant from
   a registration-supplied one. Until the claim carries its own provenance
   (`GH-DEC-2026-013` §5, second field deliberately undesigned), this surface
   records which route the value arrived by. See `PR-09`.
3. **The tenant claim is never used as the act-scope.** `binding.target` is the
   act-scope and is committed inside `view_hash`. Two different facts — which
   scope this act enters, and which tenant this person belongs to — must not
   share one field here just because they share one upstream. See
   `EvidenceModel.md` §8c and `PR-08`.

---

## 6. What this surface does with the token

- `GET /v1/approvals/{id}` and `/claim` — `approval:read`, to render.
- `POST /v1/approvals/{id}/entries` — `approval:approve`, to record a binding.
- **Never** `/consume`.
- **Never** any path containing `check` or ending `/authorize` — they 404 by
  design, and there is no "may this person approve" surface to call.

A `200` from `approval-engine` is not entitlement to view. A decision is
obtained from `access-engine` before an approval is rendered to a person
(`PR-05`) — noting that decision **attributability** is a declared open gap
(`GH-DEC-2026-010`, `FLEX-WP-0024`) and this path is not described as validated
while it stands.

---

## 7. Outstanding

| # | Item | Owner |
| --- | --- | --- |
| 1 | ~~DNS A record + Ingress + TLS for `decisions.coulomb.social`~~ — **done 2026-09-10**, cert issued, host answers 200 | `railiance-apps` / deployment |
| 2 | Submit this document to `key-cape`, closing `KEY-WP-0013-T02` | this repo, once 1 lands |
| 3 | Prove a token issued against the registration is accepted by `approval-engine` | `T08` |