persist: Phase 1 — log + kv facets on injectable in-memory backend + 28 tests

event/backend/log/kv/api over one injected backend protocol (mem default).
log: append/read/read-from, sequential per-stream seq, stream isolation.
kv: get/put/delete/has?/keys/get-or/update. conformance.sh + 3 suites, 28/28.

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

plans/persist-on-sx.md

@@ -42,7 +42,7 @@ read models (feeds, indices, audit logs) update incrementally.
 
 ## Status (rolling)
 
-`bash lib/persist/conformance.sh` → **0/0** (not yet started)
+`bash lib/persist/conformance.sh` → **28/28** (Phase 1 done)
 
 ## Ground rules
 
@@ -87,11 +87,11 @@ lib/persist/backend.sx              lib/persist/api.sx
 ```
 
 ## Phase 1 — Log + kv + in-memory backend
-- [ ] `event.sx` — event record, stream/seq helpers
-- [ ] `backend.sx` — injectable protocol + in-memory impl (log + kv)
-- [ ] `log.sx` — `append` (optimistic seq), `read`, `read-from`
-- [ ] `kv.sx` — `get`/`put`/`delete` current-state
-- [ ] `api.sx` + tests + scoreboard + conformance.sh
+- [x] `event.sx` — event record, stream/seq helpers
+- [x] `backend.sx` — injectable protocol + in-memory impl (log + kv)
+- [x] `log.sx` — `append` (optimistic seq), `read`, `read-from`
+- [x] `kv.sx` — `get`/`put`/`delete` current-state
+- [x] `api.sx` + tests + scoreboard + conformance.sh
 
 ## Phase 2 — Projections + subscriptions
 - [ ] `project.sx` — `(project stream step seed)`, incremental fold
@@ -113,7 +113,19 @@ feed/-log, flow store, mod/audit, search index, acl grants, identity sessions al
 become `persist` log or kv. Track each migration in that subsystem's plan.
 
 ## Progress log
-(loop fills this in)
+- **Phase 1 complete (28/28).** `event.sx` (event record + accessors),
+  `backend.sx` (injectable protocol + in-memory log/kv impl, closure state via
+  set!), `log.sx` (append/read/read-from, sequential per-stream seq, stream
+  isolation), `kv.sx` (get/put/delete/has?/keys/get-or/update), `api.sx`
+  (`persist/open` — mem default, backend injectable). conformance.sh + three
+  suites (event/log/kv). Gotcha logged in Blockers: `map` returns an
+  array-backed list not `equal?` to a `(list ...)` literal — assertions build
+  compared lists with list/nth.
 
 ## Blockers
-(loop fills this in)
+- **Not a blocker, a testing convention:** `map` returns an array-backed list
+  that is NOT `equal?` to a `(list ...)` cons-literal (two `map` results do
+  compare equal to each other). When asserting list-shaped results against a
+  `(list ...)` literal, build the compared value with `list`/`nth`/`cons`, not
+  `map`. `into`/list-coercion needs the IO bridge and is unusable in the
+  pure-eval harness.