Roadmap: correct the eSIM trust model (COTS UEs ARE in scope)

Earlier framing wrongly treated the eUICC as immutable and put consumer phones
out of scope. Corrected: we supply a controllable eUICC (removable sysmoEUICC
with SGP.26/private root) that trusts our local osmo-smdpp, so any COTS phone/
modem works via its LPA (EasyEUICC/OpenEUICC or lpac) with no GSMA involvement.
Update the trust-model section, architecture, Phase 3, and open questions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plan/roadmap.md

@@ -19,26 +19,39 @@ link to the core exists, it can also register new subscribers dynamically.
 - Available for testing: **srsRAN gNB + Open5GS running**, a **test eUICC / phone**.
 - Deployment targets **Pi and Android**, equally.
 
-## The hard constraint that shapes everything
+## The trust model (and how we work with it — not against it)
 
-Consumer eSIM (GSMA SGP.22 RSP) does **not** let you sideload a profile file into
-an eUICC. The device's LPA downloads the profile from an **SM-DP+** identified by
-an activation code, and **the eUICC will only trust an SM-DP+ whose certificate
-chains to the GSMA CI root**.
+Consumer eSIM (GSMA SGP.22 RSP) doesn't let you sideload a profile file into an
+eUICC: the device's LPA downloads it from an **SM-DP+**, and the eUICC only
+installs profiles from an SM-DP+ whose certificate chains to a **CI root the
+eUICC trusts**.
 
-A field-local SM-DP+ (e.g. Osmocom `osmo-smdpp`) uses **test CI keys**, which only
-**test eUICCs** accept. Therefore:
+The key realization: **we control which eUICC the device uses.** We do *not* need
+to defeat a phone's soldered factory eUICC (that would need GSMA CI accreditation).
+Instead we supply a **controllable eUICC** whose root-of-trust is ours/test — and
+then any COTS UE works with our own local SM-DP+, with **no GSMA involvement**.
+This is a productized, well-trodden path (sysmocom sells the cards and runs a
+test SM-DP+ for them).
+
+Concretely, three ingredients:
+
+1. **A controllable eUICC**, e.g. **sysmoEUICC1** — a removable eUICC in 2FF/3FF/4FF
+   plastic (or MFF2 solder) form, loaded with **test (SGP.26) or private roots**
+   instead of GSMA keys. Plugs into virtually any COTS phone/modem with a SIM slot.
+2. **A local SM-DP+** — Osmocom **`osmo-smdpp`** (proof-of-concept, ships with
+   pySim), serving *our* SAIP profiles, using SGP.26 test / private-root certs that
+   match the eUICC.
+3. **An LPA on the device** — **EasyEUICC / OpenEUICC** (Android, via UICC Carrier
+   Privileges; needs the eUICC's ISD-R to grant an ARA-M rule) or **`lpac`** for
+   modems / CLI. The LPA consumes an activation-code **QR** and drives the install.
+
+Delivery tracks:
 
 - ✅ **Software UE** — loads a profile/credential file directly. Works today, no RSP.
-- ✅ **Test eUICCs** (dev eUICC cards / test modems) — can install from a local
-  `osmo-smdpp`. This is the realistic "real eSIM" demo path.
-- ❌ **Arbitrary consumer phones with factory eUICCs** — will reject a local
-  SM-DP+. Not achievable in an ad-hoc/offline deployment without a GSMA-accredited
-  SM-DP+ (out of scope for emergency/NTN).
-
-**Implication:** target the **software UE** and **test-eUICC modems**. Treat
-generic consumer-phone eSIM as explicitly out of scope until/unless a real
-SM-DP+ relationship exists.
+- ✅ **COTS UE + controllable eUICC** — removable sysmoEUICC (test/private root) in a
+  COTS phone/modem + LPA + our local `osmo-smdpp`. The real eSIM path.
+- ⚠️ **A phone's untouched factory eUICC** — would reject a local SM-DP+ (needs GSMA
+  CI accreditation). We sidestep this by supplying the eUICC, so it's not a blocker.
 
 ## Where we are (done)
 
@@ -59,7 +72,9 @@ Drop device (Pi / Android)
 
 Two delivery tracks:
   Track S — Software UE:      profile file → soft-UE → attach       (Phase 1)
-  Track E — Test eUICC:   QR activation code → LPA → local SM-DP+
+  Track E — COTS UE + eUICC:  COTS phone/modem with a controllable
+                              (removable/private-root) eUICC + LPA:
+                              QR activation code → LPA → local SM-DP+
                               → eUICC installs SAIP profile → attach (Phase 3)
 ```
 
@@ -89,15 +104,20 @@ a test eUICC) on srsRAN+Open5GS; confirm authentication succeeds.
   queue dynamic registrations for when the core link returns.
 - Deliverable: a drop that works fully offline from a pre-loaded batch.
 
-### Phase 3 — Test-eUICC via local SM-DP+ (the real eSIM last mile)
-- Stand up `osmo-smdpp` on the drop; wire our SAIP profiles into it; manage the
-  (test) CI cert chain.
+### Phase 3 — COTS UE via local SM-DP+ (the real eSIM last mile)
+- Obtain **controllable eUICCs** (removable sysmoEUICC1 with SGP.26/private root, or
+  equivalent) and confirm an **LPA** on the target UEs (EasyEUICC/OpenEUICC on
+  Android; `lpac` for modems). Verify the eUICC's ISD-R grants the ARA-M rule the
+  LPA needs.
+- Stand up **`osmo-smdpp`** on the drop; wire our SAIP profiles into it; manage the
+  matching (SGP.26/private) CI cert chain.
 - Complete the SAIP profile to an installable one (PIN/PUK, ARR, security domain,
-  remaining mandatory PEs) — **validated against the test eUICC** (this is where
+  remaining mandatory PEs) — **validated against the real eUICC** (this is where
   the deferred SAIP PE work finally gets card-validated rather than guessed).
-- Captive portal renders the LPA activation-code **QR**; test device installs and
-  attaches.
-- Deliverable: test-eUICC device → scan QR → eSIM installed → on the network.
+  Cross-check against pySim's known-good test profiles.
+- Captive portal renders the LPA activation-code **QR**; a COTS phone/modem (with
+  the controllable eUICC) installs and attaches.
+- Deliverable: COTS UE + controllable eUICC → scan QR → eSIM installed → on the network.
 
 ### Phase 4 — Field hardening (Pi + Android, first-class)
 Offline/power/thermal, monitoring/observability, capacity, subscriber
@@ -117,7 +137,10 @@ revoke/expire/resync, backhaul-aware dynamic registration, secure batch loading.
 - **Open5GS access** — reachable from the dev environment, or do you run sync?
   MongoDB URI, slice SST/SD, APN/DNN, PLMN to match the gNB.
 - **SM-DP+** — OK to vendor/run `osmo-smdpp` on the drop, or a different RSP?
-- **Test eUICCs** — which test eUICC(s)/modems are the real targets (so Phase 3
-  profile completion is validated against them)?
+- **Controllable eUICCs** — which eUICC do we standardize on (sysmoEUICC1 with
+  SGP.26 vs private root)? Do the current "test eUICC/phone" you have match the
+  SGP.26 root osmo-smdpp ships, or do we need a private-root batch?
+- **LPA** — EasyEUICC/OpenEUICC (Android) and/or `lpac` (modems) as the on-device
+  LPA? Any UEs whose SIM slot / carrier-privilege behavior needs checking?
 - **Batch model** — expected batch size per drop; how batches are provisioned and
   loaded (offline media vs one-time backhaul).