diff --git a/lib/acl/api.sx b/lib/acl/api.sx
new file mode 100644
index 00000000..d0ec64a2
--- /dev/null
+++ b/lib/acl/api.sx
@@ -0,0 +1,31 @@
+;; lib/acl/api.sx — public ACL surface over an implicit current db.
+;;
+;; Callers load a fact set once, then issue decisions without threading the db
+;; through every call. The current db is module state; (acl/load! facts) rebuilds
+;; it. This is the boundary the rest of rose-ash imports.
+
+(define acl-current-db nil)
+
+;; Replace the current fact base. Rebuilds the Datalog db under the active
+;; ruleset (see lib/acl/engine.sx).
+(define
+  acl/load!
+  (fn
+    (facts)
+    (do (set! acl-current-db (acl-build-db facts)) acl-current-db)))
+
+;; Ensure a db exists, building an empty one on first use.
+(define
+  acl-ensure-db!
+  (fn
+    ()
+    (do
+      (when
+        (= acl-current-db nil)
+        (set! acl-current-db (acl-build-db (list))))
+      acl-current-db)))
+
+;; Public decision against the current db.
+(define
+  acl/permit?
+  (fn (subj act res) (acl-permit? (acl-ensure-db!) subj act res)))
diff --git a/lib/acl/conformance.conf b/lib/acl/conformance.conf
new file mode 100644
index 00000000..4338be18
--- /dev/null
+++ b/lib/acl/conformance.conf
@@ -0,0 +1,25 @@
+# ACL conformance config — sourced by lib/guest/conformance.sh.
+
+LANG_NAME=acl
+MODE=dict
+
+PRELOADS=(
+  lib/datalog/tokenizer.sx
+  lib/datalog/parser.sx
+  lib/datalog/unify.sx
+  lib/datalog/db.sx
+  lib/datalog/builtins.sx
+  lib/datalog/aggregates.sx
+  lib/datalog/strata.sx
+  lib/datalog/eval.sx
+  lib/datalog/api.sx
+  lib/datalog/magic.sx
+  lib/acl/schema.sx
+  lib/acl/facts.sx
+  lib/acl/engine.sx
+  lib/acl/api.sx
+)
+
+SUITES=(
+  "direct:lib/acl/tests/direct.sx:(acl-direct-tests-run!)"
+)
diff --git a/lib/acl/conformance.sh b/lib/acl/conformance.sh
new file mode 100755
index 00000000..225bea24
--- /dev/null
+++ b/lib/acl/conformance.sh
@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+# Thin wrapper — see lib/guest/conformance.sh and lib/acl/conformance.conf.
+exec bash "$(dirname "$0")/../guest/conformance.sh" "$(dirname "$0")/conformance.conf" "$@"
diff --git a/lib/acl/engine.sx b/lib/acl/engine.sx
new file mode 100644
index 00000000..ee58fd63
--- /dev/null
+++ b/lib/acl/engine.sx
@@ -0,0 +1,29 @@
+;; lib/acl/engine.sx — ACL ruleset + decision reducer over lib/datalog/.
+;;
+;; The engine is a thin layer: it owns the permit ruleset (SX data rules) and
+;; reduces a (subject, action, resource) decision to a Datalog query against a
+;; db built from EDB facts. The rule engine itself is Datalog's.
+;;
+;; Phase 1 policy — direct grants with deny-overrides:
+;;
+;;   permit(S, A, R) :- grant(S, A, R), not deny(S, A, R).
+;;
+;; A grant permits unless an explicit deny names the same (S, A, R). Deny wins:
+;; the negated literal {:neg (deny S A R)} stratifies cleanly because deny is an
+;; EDB relation (no rule derives it), so the fixpoint is well-defined.
+
+(define
+  acl-phase1-rules
+  (quote ((permit S A R <- (grant S A R) {:neg (deny S A R)}))))
+
+;; Build a Datalog db from a list of EDB facts under the Phase 1 ruleset.
+(define acl-build-db (fn (facts) (dl-program-data facts acl-phase1-rules)))
+
+;; Core decision: does the db permit subject S to perform action A on
+;; resource R? Reduces to a ground Datalog query on the derived `permit`
+;; relation — non-empty result means permitted.
+(define
+  acl-permit?
+  (fn
+    (db subj act res)
+    (> (len (dl-query db (list (quote permit) subj act res))) 0)))
diff --git a/lib/acl/facts.sx b/lib/acl/facts.sx
new file mode 100644
index 00000000..68990f72
--- /dev/null
+++ b/lib/acl/facts.sx
@@ -0,0 +1,13 @@
+;; lib/acl/facts.sx — EDB fact constructors.
+;;
+;; Each constructor returns a Datalog fact tuple (a list whose head is the
+;; predicate symbol). These are the only shapes lib/acl/engine.sx feeds to
+;; lib/datalog/. Phase 1 covers actor/resource/grant/deny.
+
+(define acl-actor (fn (id kind) (list (quote actor) id kind)))
+
+(define acl-resource-fact (fn (id kind) (list (quote resource) id kind)))
+
+(define acl-grant (fn (subj act res) (list (quote grant) subj act res)))
+
+(define acl-deny (fn (subj act res) (list (quote deny) subj act res)))
diff --git a/lib/acl/schema.sx b/lib/acl/schema.sx
new file mode 100644
index 00000000..9bf0a618
--- /dev/null
+++ b/lib/acl/schema.sx
@@ -0,0 +1,48 @@
+;; lib/acl/schema.sx — ACL sorts and EDB predicate vocabulary.
+;;
+;; Datalog is untyped; this module is the schema-as-data layer. It declares
+;; the subject/resource/action sorts and the arity of every EDB predicate the
+;; ACL engine recognises, plus light validators. Facts that pass these checks
+;; are well-formed inputs to lib/acl/engine.sx.
+
+(define acl-subject-kinds (quote (user group role service)))
+(define acl-resource-kinds (quote (page post thread peer)))
+
+;; Actions are open-ended (a grant may name any action symbol), but these are
+;; the platform's well-known verbs.
+(define acl-actions (quote (read edit comment moderate federate)))
+
+;; EDB predicate name -> arity. Phase 1 uses actor/resource/grant/deny;
+;; member_of and child_of are reserved for Phase 2 inheritance.
+(define acl-edb-arity {:child_of 2 :actor 2 :member_of 2 :deny 3 :grant 3 :resource 2})
+
+(define
+  acl-member?
+  (fn
+    (x xs)
+    (cond
+      ((= (len xs) 0) false)
+      ((= (first xs) x) true)
+      (else (acl-member? x (rest xs))))))
+
+(define acl-subject-kind? (fn (k) (acl-member? k acl-subject-kinds)))
+
+(define acl-resource-kind? (fn (k) (acl-member? k acl-resource-kinds)))
+
+(define acl-known-action? (fn (a) (acl-member? a acl-actions)))
+
+;; A fact is a list whose head is a predicate symbol. Valid when the predicate
+;; is known and the argument count matches the declared arity.
+(define
+  acl-fact-valid?
+  (fn
+    (f)
+    (and
+      (list? f)
+      (> (len f) 0)
+      (symbol? (first f))
+      (let
+        ((pred (symbol->string (first f))))
+        (and
+          (has-key? acl-edb-arity pred)
+          (= (- (len f) 1) (get acl-edb-arity pred)))))))
diff --git a/lib/acl/scoreboard.json b/lib/acl/scoreboard.json
new file mode 100644
index 00000000..52b81beb
--- /dev/null
+++ b/lib/acl/scoreboard.json
@@ -0,0 +1,10 @@
+{
+  "lang": "acl",
+  "total_passed": 24,
+  "total_failed": 0,
+  "total": 24,
+  "suites": [
+    {"name":"direct","passed":24,"failed":0,"total":24}
+  ],
+  "generated": "2026-06-06T16:31:36+00:00"
+}
diff --git a/lib/acl/scoreboard.md b/lib/acl/scoreboard.md
new file mode 100644
index 00000000..8ba9fd0b
--- /dev/null
+++ b/lib/acl/scoreboard.md
@@ -0,0 +1,7 @@
+# acl scoreboard
+
+**24 / 24 passing** (0 failure(s)).
+
+| Suite | Passed | Total | Status |
+|-------|--------|-------|--------|
+| direct | 24 | 24 | ok |
diff --git a/lib/acl/tests/direct.sx b/lib/acl/tests/direct.sx
new file mode 100644
index 00000000..279f6ba8
--- /dev/null
+++ b/lib/acl/tests/direct.sx
@@ -0,0 +1,170 @@
+;; lib/acl/tests/direct.sx — Phase 1: direct grants + deny-overrides.
+
+(define acl-dt-pass 0)
+(define acl-dt-fail 0)
+(define acl-dt-failures (list))
+
+(define
+  acl-dt-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! acl-dt-pass (+ acl-dt-pass 1))
+      (do
+        (set! acl-dt-fail (+ acl-dt-fail 1))
+        (append!
+          acl-dt-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+;; A small fixture used by most cases: alice can read page1, is denied edit on
+;; page1, and a service may federate peer1.
+(define
+  acl-dt-fixture
+  (fn
+    ()
+    (acl-build-db
+      (list
+        (acl-actor (quote alice) (quote user))
+        (acl-actor (quote svc1) (quote service))
+        (acl-resource-fact (quote page1) (quote page))
+        (acl-resource-fact (quote peer1) (quote peer))
+        (acl-grant (quote alice) (quote read) (quote page1))
+        (acl-grant (quote alice) (quote edit) (quote page1))
+        (acl-deny (quote alice) (quote edit) (quote page1))
+        (acl-grant (quote svc1) (quote federate) (quote peer1))))))
+
+(define
+  acl-dt-run-all!
+  (fn
+    ()
+    (let
+      ((db (acl-dt-fixture)))
+      (do
+        (acl-dt-check!
+          "direct grant permits"
+          (acl-permit? db (quote alice) (quote read) (quote page1))
+          true)
+        (acl-dt-check!
+          "service grant permits federate"
+          (acl-permit? db (quote svc1) (quote federate) (quote peer1))
+          true)
+        (acl-dt-check!
+          "missing action denied"
+          (acl-permit? db (quote alice) (quote comment) (quote page1))
+          false)
+        (acl-dt-check!
+          "missing resource denied"
+          (acl-permit? db (quote alice) (quote read) (quote page2))
+          false)
+        (acl-dt-check!
+          "missing subject denied"
+          (acl-permit? db (quote bob) (quote read) (quote page1))
+          false)
+        (acl-dt-check!
+          "wrong subject for service grant denied"
+          (acl-permit? db (quote alice) (quote federate) (quote peer1))
+          false)
+        (acl-dt-check!
+          "grant plus deny -> deny wins"
+          (acl-permit? db (quote alice) (quote edit) (quote page1))
+          false)
+        (acl-dt-check!
+          "deny alone still denies"
+          (acl-permit?
+            (acl-build-db
+              (list (acl-deny (quote alice) (quote read) (quote page1))))
+            (quote alice)
+            (quote read)
+            (quote page1))
+          false)
+        (acl-dt-check!
+          "deny on edit does not block read"
+          (acl-permit? db (quote alice) (quote read) (quote page1))
+          true)
+        (acl-dt-check!
+          "empty db denies"
+          (acl-permit?
+            (acl-build-db (list))
+            (quote alice)
+            (quote read)
+            (quote page1))
+          false)
+        (let
+          ((db2 (acl-build-db (list (acl-grant (quote a) (quote read) (quote r)) (acl-grant (quote b) (quote read) (quote r)) (acl-deny (quote b) (quote read) (quote r))))))
+          (do
+            (acl-dt-check!
+              "subject a allowed"
+              (acl-permit? db2 (quote a) (quote read) (quote r))
+              true)
+            (acl-dt-check!
+              "subject b denied by override"
+              (acl-permit? db2 (quote b) (quote read) (quote r))
+              false)))
+        (let
+          ((db3 (acl-build-db (list (acl-actor (quote editors) (quote role)) (acl-grant (quote editors) (quote edit) (quote post1))))))
+          (acl-dt-check!
+            "role subject direct grant"
+            (acl-permit? db3 (quote editors) (quote edit) (quote post1))
+            true))
+        (do
+          (acl/load!
+            (list
+              (acl-grant (quote carol) (quote moderate) (quote thread1))))
+          (acl-dt-check!
+            "api permit via current db"
+            (acl/permit? (quote carol) (quote moderate) (quote thread1))
+            true)
+          (acl-dt-check!
+            "api deny via current db"
+            (acl/permit? (quote carol) (quote read) (quote thread1))
+            false))
+        (do
+          (acl/load! (list))
+          (acl-dt-check!
+            "api reload clears prior grants"
+            (acl/permit? (quote carol) (quote moderate) (quote thread1))
+            false))
+        (acl-dt-check!
+          "schema grant arity valid"
+          (acl-fact-valid? (acl-grant (quote x) (quote read) (quote y)))
+          true)
+        (acl-dt-check!
+          "schema bad arity invalid"
+          (acl-fact-valid? (list (quote grant) (quote x)))
+          false)
+        (acl-dt-check!
+          "schema unknown predicate invalid"
+          (acl-fact-valid? (list (quote frobnicate) (quote x)))
+          false)
+        (acl-dt-check!
+          "schema subject kind known"
+          (acl-subject-kind? (quote service))
+          true)
+        (acl-dt-check!
+          "schema resource kind unknown"
+          (acl-resource-kind? (quote galaxy))
+          false)
+        (acl-dt-check!
+          "schema known action"
+          (acl-known-action? (quote moderate))
+          true)
+        (acl-dt-check!
+          "grant constructor shape"
+          (acl-grant (quote u) (quote read) (quote p))
+          (list (quote grant) (quote u) (quote read) (quote p)))
+        (acl-dt-check!
+          "actor constructor shape"
+          (acl-actor (quote u) (quote user))
+          (list (quote actor) (quote u) (quote user)))))))
+
+(define
+  acl-direct-tests-run!
+  (fn
+    ()
+    (do
+      (set! acl-dt-pass 0)
+      (set! acl-dt-fail 0)
+      (set! acl-dt-failures (list))
+      (acl-dt-run-all!)
+      {:failures acl-dt-failures :total (+ acl-dt-pass acl-dt-fail) :passed acl-dt-pass :failed acl-dt-fail})))
diff --git a/plans/acl-on-sx.md b/plans/acl-on-sx.md
index 898c8138..c4facd8f 100644
--- a/plans/acl-on-sx.md
+++ b/plans/acl-on-sx.md
@@ -15,7 +15,7 @@ and federation extension. Reuses `lib/datalog/` evaluator and term model where p
 
 ## Status (rolling)
 
-`bash lib/acl/conformance.sh` → **0/0** (not yet started)
+`bash lib/acl/conformance.sh` → **24/24** (Phase 1 complete)
 
 ## Ground rules
 
@@ -57,15 +57,15 @@ lib/acl/facts.sx                  — builds Datalog query
 
 ## Phase 1 — Direct grants
 
-- [ ] `lib/acl/schema.sx` — sorts: subject {user, group, role, service}, action,
+- [x] `lib/acl/schema.sx` — sorts: subject {user, group, role, service}, action,
   resource {page, post, thread, peer}
-- [ ] `lib/acl/facts.sx` — `actor`, `resource`, `grant`, `deny` predicates as Datalog
+- [x] `lib/acl/facts.sx` — `actor`, `resource`, `grant`, `deny` predicates as Datalog
   EDB
-- [ ] `lib/acl/engine.sx` — `(permit? subj act res db)` reduces to Datalog query
-- [ ] `lib/acl/api.sx` — public `(acl/permit? ...)` taking implicit current db
-- [ ] `lib/acl/tests/direct.sx` — 15+ cases: direct grant, missing grant, explicit deny
-- [ ] `lib/acl/scoreboard.{json,md}` baseline
-- [ ] `lib/acl/conformance.sh` runs the suite
+- [x] `lib/acl/engine.sx` — `(permit? subj act res db)` reduces to Datalog query
+- [x] `lib/acl/api.sx` — public `(acl/permit? ...)` taking implicit current db
+- [x] `lib/acl/tests/direct.sx` — 15+ cases: direct grant, missing grant, explicit deny
+- [x] `lib/acl/scoreboard.{json,md}` baseline
+- [x] `lib/acl/conformance.sh` runs the suite
 
 ## Phase 2 — Inheritance
 
@@ -95,7 +95,34 @@ lib/acl/facts.sx                  — builds Datalog query
 
 ## Progress log
 
-(loop fills this in)
+- **Phase 1 complete (24/24).** ACL is a thin layer over `lib/datalog/`:
+  - `schema.sx` — sorts (subject/resource kinds, well-known actions) + EDB
+    predicate arity table + `acl-fact-valid?` validator. Schema is data, since
+    Datalog is untyped.
+  - `facts.sx` — `acl-actor`/`acl-resource-fact`/`acl-grant`/`acl-deny`
+    constructors returning Datalog fact tuples.
+  - `engine.sx` — owns the ruleset `acl-phase1-rules` and reduces decisions to
+    `dl-query`. `acl-build-db` = `dl-program-data facts rules`; `acl-permit?` =
+    non-empty `(permit S A R)` query.
+  - `api.sx` — `acl/load!` rebuilds an implicit current db; `acl/permit?` queries
+    it. (Slash-symbols like `acl/permit?` parse fine as single tokens.)
+  - **deny-overrides** encoded as `permit(S,A,R) :- grant(S,A,R), not deny(S,A,R)`.
+    Stratifies cleanly because `deny` is EDB-only (no rule derives it). Verified:
+    grant+deny on same (S,A,R) → denied.
+  - Conformance: `conformance.conf` (datalog preloads + acl modules) + thin
+    `conformance.sh` wrapper over `lib/guest/conformance.sh`. Scoreboard
+    generated by the shared driver.
+  - **Shared-plumbing note (for eventual `lib/guest/rules/`):** the
+    `build-db = dl-program-data(facts, rules)` + `decide = non-empty ground query`
+    shape is exactly what mod-sx (Prolog moderation) will also need. The reusable
+    seam is engine.sx's two functions — facts→db and ground-query→bool — both
+    pure pass-throughs to the rule engine. Not extracting yet (wait for mod-sx as
+    second consumer per ground rules).
+  - **Tooling note:** sx-tree path-based edit tools (`sx_replace_node`,
+    `sx_read_subtree` with a path) ignored the path argument in this worktree
+    (always resolved to index 0 / `[0,..]`). `sx_write_file`, `sx_validate`,
+    `sx_find_all`, `sx_eval` all work; used full-file rewrites instead of path
+    edits.
 
 ## Blockers