radar: pass 10 — W6 guarded lifecycle FSM (mod+identity): shared principle, divergent structure (SX table vs Erlang gen_server), not a lib

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plans/abstractions.md

@@ -12,6 +12,11 @@ Anything short → _Watching_ (what's missing) or _Rejected_ (why).
 
 ## Last scan
 
+- **Date:** 2026-06-07 (radar loop, pass 10)
+- **Pass 10:** commerce/content/events/identity advancing (content 238/238). Probed a
+  shape outside the routing table — **guarded lifecycle state machines** (mod/lifecycle +
+  identity/membership) → new W6: shared *design principle*, divergent *structure*
+  (SX transition-table vs Erlang gen_server), NOT an extraction target. No gate-clearer.
 - **Date:** 2026-06-07 (radar loop, pass 9)
 - **Pass 9:** `commerce` + `content` reached Phase 2 (`content` 162/162). **Key find:
   `content` built its op log directly on `persist/log`** (backend-injected, append+replay-
@@ -227,6 +232,24 @@ Anything short → _Watching_ (what's missing) or _Rejected_ (why).
 
 ---
 
+### W6 · Guarded lifecycle state machine (illegal transition = explicit error)
+- Recurs as a **design principle**, NOT a shared structure (found pass 10):
+  - `mod/lib/mod/lifecycle.sx` — pure SX: immutable case `{:state :error :history …}`,
+    explicit transition table `mod/lc-transitions` (:31), illegal transition returns the
+    case unchanged with `:error` set. States open→triaged→decided→appealed→final.
+  - `identity/lib/identity/membership.sx` — an **Erlang `gen_server`** fragment (identity
+    runs on erlang-on-sx): a `receive` loop with `case find(...) of … {error, St}` guards.
+    States none→pending→active→lapsed→revoked.
+- **Both share the guideline** ("invalid transitions are explicit errors, never silent
+  no-ops") but **implement it substrate-idiomatically** — SX transition-table over
+  immutable values vs an Erlang process loop with per-message case guards. Same W1/`api.sx`
+  trap: shared *idea*, divergent *structure*.
+- **Disposition:** not an extraction target — the FSM mechanism is ~10 substrate-specific
+  lines; the value is in each domain's state graph, not the plumbing. At most a **design
+  guideline** ("model lifecycle as a guarded FSM with explicit-error transitions"). Watch
+  whether commerce-checkout / events-booking add their own — if so it confirms the
+  *guideline*, still not a lib. Do not propose extracting a shared state-machine lib.
+
 ## Rejected (considered, declined — do not re-propose)
 
 - **"Continuous auto-implementing abstractor loop."** Rejected at design time: an