docs(status): record the first end-to-end three-party observation

An auth token from sandbox.personserver.dev opened whoami.aauth.dev —
agent to Agent Provider to Person Server to a resource written by
neither team, on released artefacts. The directed sub is identical
across the person, resource and auth tokens, so the identity survived
every hop.

Recorded with attribution rather than as our own result: psd observed
it, and reproducing it from their written description is still pending.
Two implementations agreeing is only evidence about the protocol when
both actually ran.

The artefact versions are stated because they are uneven. The Person
Server was the released psd:0.2.0; the Agent Provider was apd 0.2.0,
since the sandbox roll waits on the release — confirmed by
accept_signature_algs still absent from its metadata at 04:14 UTC,
inside the window of the run. The apd half of this result belongs to a
three-release-old artefact and will be re-run against 0.5.0.

Claude-Session: https://claude.ai/code/session_01By4kRh2Tj2HAgfqKjv8zSj

Author: AndriiTsok

docs/STATUS.md

@@ -112,6 +112,24 @@ of it no live counterparty exists yet.
   Worth recording because I got this wrong twice by probing unauthenticated:
   the resource states its requirements only *after* a signature verifies, so
   what a resource supports is not discoverable without first being someone.
+- **The full three-party chain, observed end to end** — agent → Agent Provider →
+  Person Server → a resource written by neither team. `psd` ran it on
+  2026-08-16, 04:11–04:15 UTC: an auth token minted by `sandbox.personserver.dev`
+  opened `whoami.aauth.dev`, which answered `200` with
+
+  ```json
+  {"iss":"https://sandbox.personserver.dev","sub":"<directed sub>"}
+  ```
+
+  The same directed `sub` appears in the person token, the resource token and the
+  auth token, so the identity survived every hop.
+
+  **Attribution and artefacts:** observed by the psd maintainers, not by apd, and
+  reproduction from their written description is pending. The Person Server was
+  the released `psd:0.2.0`; the Agent Provider was `apd` **0.2.0** — the sandbox
+  had not been rolled, confirmed by `accept_signature_algs` still being absent
+  from its metadata at 04:14 UTC. The apd half of this result therefore belongs
+  to a three-release-old artefact, and will be re-run against `0.5.0`.
 - Cross-implementation conformance against psd: 27/27.
 - The sandbox deployment itself, and every runnable example in the docs.