Slice 3 Part A — hub v0.118.0 / v0.118.1, live evidence (2026-09-18)

Method: endpoint-level, plus one real e-mail read in the operator's own inbox. No browser on DooPlex. Nothing was installed, nothing removed; the deploy endpoint was never touched.

1. The wire already worked — measured BEFORE writing any code

Read-only copy of the live hub.db (+ -wal, or it is hours stale):

demo-felhom  14:12 UTC  language='hu'   controller 0.255.0
demo-hp      14:09 UTC  language='en'   controller 0.255.0
drill-r50 / peti-felhom / tester-1      language=<ABSENT>  (0.213.0 / 0.115.0 / 0.245.0)

The positive and the negative control in one read: every box on ≥ 0.247.0 publishes the field, every older one sends nothing at all — which is the case the empty default exists for.

2. The migration applied

reports.language          present: True
customer_configs.language present: True
customer_configs.language = 'hu' for all five customers (the default backfill)

The first reports written by the NEW hub, minutes after the sync, carry the denormalised value:

demo-felhom  id=25717  14:22:59  language='hu'
demo-hp      id=25718  14:23:00  language='en'

Rollback, written before the sync: revert the manifest tag to 0.117.0 and sync. The two columns stay and need no undo — v0.117.0 neither reads nor writes them and both carry a DEFAULT, so every INSERT the old binary performs still succeeds. Rolling back the image is the whole rollback.

3. One real e-mail, both directions, 74 seconds apart

The path is the product's own: sign in to the box, press Send test notification on the notifications page (POST /settings/notifications/test) — which is what a customer's own click does. The box POSTs event_type=test to the hub, and the hub composes the mail.

Box reporting en — 14:30:43 UTC, to the household address drill@felhom.eu:

Subject: [Felhom] Test notification
         Dear Customer,
         This is a test notification from the Felhom monitoring system.
         Notifications are working correctly.
         Best regards,
         Felhom.eu monitoring

The same button, box switched to hu — 14:31:57 UTC, same address:

Subject: [Felhom] Teszt értesítés
         Kedves Ügyfél! Ez egy teszt értesítés a Felhom monitoring rendszerből.
         Az értesítések megfelelően működnek. Üdvözlettel, Felhom.eu monitoring

The Hungarian is byte-for-byte the literal that shipped in v0.117.0 — it was extracted into the bundle by script, never retyped.

The operator's copy is identical in both, to admin@felhom.eu: [Felhom] ✅ demo-hp: teszt / operator channel OK. That is the half worth stating: the household's language changed twice and nothing the operator reads moved.

4. What this did NOT prove

message_customer has no live proof yet. No box sends it until controller v0.256.0 (Part B). The hub half is covered by tests only.
The test mail bypasses FormatCustomerEmail, so this proof exercises the bundle and the language resolution, not the event-mail wrapper. The wrapper's live proof waits for Part B.
Nobody looked at these mails in a mail CLIENT. They are plain text; the bytes above are what was sent.

5. A lapse, recorded

Earlier in this same session (slice 2 releases B/C/D) I left five probe scripts in the guest's /tmp — probeB.sh, probeB2.sh, probeB3.sh, probeC.sh, probeD.sh — and they carried the controller password inline. The standing rule says a credential-bearing helper is deleted from /tmp on both host and guest when done; they sat there for hours instead. Found while cleaning up after this proof, by grepping my own litter for secret-shaped strings before deleting it. All are now shredded, along with this run's password file on the host, the guest and DooPlex. This run used a file→file password (never an inline literal), which is why its own scripts were clean.

6. State at the end

Hub 0.118.1, Synced/Healthy, clean startup log. demo-hp back on Hungarian. Nothing installed, nothing removed, no floor change, no golden. Guest /tmp clean.