feat(cfold): canonicalize custom test layout

tests/matrix-synapse/PARITY.md

@@ -8,7 +8,7 @@ messages, federation) in Python tests adapted to the ephemeral per-run-deploy mo
 
 | recipe-maintainer file | cc-ci file | what's verified | status |
 |---|---|---|---|
-| (no health_check.py in the recipe-maintainer corpus) | `tests/matrix-synapse/functional/test_health_check.py` | HTTP 200 + JSON document from `/_matrix/client/versions` (the synapse client API). | **Phase-2 health_check** (aligned with the parity-port convention; the corpus has no health_check.py to port from). |
+| (no health_check.py in the recipe-maintainer corpus) | `tests/matrix-synapse/custom/test_health_check.py` | HTTP 200 + JSON document from `/_matrix/client/versions` (the synapse client API). | **Phase-2 health_check** (aligned with the parity-port convention; the corpus has no health_check.py to port from). |
 | `recipe-info/matrix-synapse/tests/compress_state.sh` | (deferred to Q4 follow-up — synapse_auto_compressor + state-group bloat) | The original creates state groups WITHOUT edges (full snapshots — Synapse's bloat pattern), runs the synapse_auto_compressor, asserts row counts drop. Requires per-run admin user pre-seeded + a long-running synapse + access to the synapse_auto_compressor binary. | **deferred** (operational complexity; needs custom install_steps.sh + admin user pre-seeding) |
 | `recipe-info/matrix-synapse/tests/test_complexity_limit.sh` | (deferred to Q4 follow-up — rate-limit behaviour) | Exercises Synapse's complexity-limit rejection of huge events. | **deferred** (load-test class; needs many-event setup) |
 | `recipe-info/matrix-synapse/tests/test_purge.sh` | (deferred to Q4 follow-up — admin purge commands) | Tests the abra.sh `db purge_history`, `db purge_room` etc. helpers. Operational tests against the recipe's helper shell wrappers. | **deferred** (recipe-helper-script tests, not synapse-behavior tests; orthogonal to Phase-2 P3) |
@@ -28,8 +28,8 @@ Three specific tests landed (beyond parity health_check):
 
 | cc-ci file | what's verified | rationale |
 |---|---|---|
-| `tests/matrix-synapse/functional/test_federation_version.py` | GET `/_matrix/federation/v1/version` → 200, JSON with `server.name == "Synapse"`, non-empty `server.version`. | Plan §4.3 prescribed. Federation discovery endpoint — the recipe's "is this a real Synapse, federation-ready" surface. Non-vacuous: a Dendrite or misconfigured federation subsystem fails. |
-| `tests/matrix-synapse/functional/test_register_and_message.py` | **Plan §4.3 prescribed create-and-read-back.** Reads the abra-generated `registration` shared secret from the synapse container; registers two users (alice + bob) via `/_synapse/admin/v1/register` (HMAC-SHA1 nonce flow); both login via `/_matrix/client/v3/login`; alice creates a private_chat room; invites bob; bob joins; alice sends a uniquely-marked m.room.message; bob reads the room's messages and finds the marker. | The canonical Matrix create-and-read-back, exercising registration + login + room create/invite/join + send/receive across the full client API. Non-vacuous: each step fails at the level it's broken (admin API, login, room ops, send/receive); marker assertion confirms the message actually round-tripped across two users. |
+| `tests/matrix-synapse/custom/test_federation_version.py` | GET `/_matrix/federation/v1/version` → 200, JSON with `server.name == "Synapse"`, non-empty `server.version`. | Plan §4.3 prescribed. Federation discovery endpoint — the recipe's "is this a real Synapse, federation-ready" surface. Non-vacuous: a Dendrite or misconfigured federation subsystem fails. |
+| `tests/matrix-synapse/custom/test_register_and_message.py` | **Plan §4.3 prescribed create-and-read-back.** Reads the abra-generated `registration` shared secret from the synapse container; registers two users (alice + bob) via `/_synapse/admin/v1/register` (HMAC-SHA1 nonce flow); both login via `/_matrix/client/v3/login`; alice creates a private_chat room; invites bob; bob joins; alice sends a uniquely-marked m.room.message; bob reads the room's messages and finds the marker. | The canonical Matrix create-and-read-back, exercising registration + login + room create/invite/join + send/receive across the full client API. Non-vacuous: each step fails at the level it's broken (admin API, login, room ops, send/receive); marker assertion confirms the message actually round-tripped across two users. |
 
 Media upload/download deferred — would add a fourth specific test (`media_upload_roundtrip`)
 using `/_matrix/media/v3/upload` + `/_matrix/media/v3/download/<server>/<media_id>`. Not in this