Let a human token carry the zone it is issued into, without relabelling anyone

KEY-WP-0013-T05's tenant blocker did not need the decision it was waiting on. The
two proposed resolutions differ in where a human's tenant comes from -- the
directory record, or the client registration -- and an implementation exists that
is correct under either, so the choice can be made later without another
migration.

A client registration may now declare a tenant. humanTenant() resolves it by four
rules: no declaration keeps the directory answer unchanged; a declared zone
applies where the directory has placed the user nowhere; agreement passes; and a
declared zone conflicting with a directory assignment refuses issuance rather
than relabelling the user.

The refusal is the design, not an edge case. A registration can bind a zone for
unplaced users and can never move a placed one, so this gets the approval chain
its tenant:platform without writing a general cross-tenant override into the
issuer. It fails closed rather than picking a winner, because either answer would
be a silent cross-tenant assertion, and it reports 403 with
error_type: tenant_binding so an operator can tell a misconfigured registration
from a rejected login. If the owners later populate directory tenants, the same
code stops supplying the zone and starts enforcing agreement with it.

Safe only because client registrations are static and deployment-owned. The
tenant contract records that this rule must be revisited if dynamic client
registration is ever admitted.

Tests cover all four rules; neutering the conflict check fails the relabel test
rather than passing silently.

T05 now waits on one thing only: the client_id and callback URI from
informed-decision once it has a deployed origin.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016uV8zoCKpA1WRAxsKRYbdH

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1182213@bnt-lap001
Assistant-Session: 966597b9-ae61-46a4-8b9e-1594ab3ec4ad

docs/approval-engine-provisioning-request.yaml

@@ -49,14 +49,18 @@ human_registration:
   client_type: public
   grant: authorization_code + S256 PKCE
   never: [approval:consume]
-  blocked_on_keycape_side: |
-    A human access token cannot carry tenant:platform today. The tenant claim on
-    a human token is resolved from the directory user (effectiveTenant in
-    src/internal/server/oidc/token.go), not from the client registration, and no
-    adapter populates User.Tenant -- so every human token defaults to
-    tenant:coulomb. approval-engine compares tenant by exact string equality and
-    refuses near-miss spellings, so an approver token would be rejected. This
-    must be resolved before the registration is issued, not after.
+  # Required. Without it the token carries tenant:coulomb from the directory
+  # default and approval-engine refuses it. See docs/tenant-claim-contract.md.
+  tenant: tenant:platform
+  keycape_side_resolved: |
+    2026-09-09: a human token can now carry tenant:platform. A client
+    registration may declare a tenant; humanTenant() supplies it when the
+    directory has not placed the user, requires agreement when it has, and
+    refuses issuance on conflict rather than relabelling. Safe only because
+    registrations are static and deployment-owned. Still outstanding from
+    elsewhere: the exact client_id and callback URI from informed-decision
+    (INFD-WP-0001-T07), and whether the owners prefer the directory-sourced
+    resolution instead, which this implementation degrades into cleanly.
 verification:
   # The first two lines are now one runnable command per client; see
   # docs/native-authentication.md, "Verifying a live registration". It writes