acl: hardening suite (+25) — diamonds, cycles, validation, audit save/restore

New adversarial/cross-phase coverage: diamond resource+group hierarchies
(deny wins per path), chain inheritance + leaf deny, cycle termination,
multi-peer delegation, fact validation, audit snapshot/restore round-trip.
Adds acl-validate-facts/acl-facts-valid? (schema) and acl-audit-snapshot/
restore!/copy (audit). Fixed acl-audit-restore! rebuilding the live log via
map (append! silently no-ops on map-derived lists).

Suite is prover-free: a substrate JIT bug loops the recursive proof
reconstructor on deep chains in warm processes (documented in Blockers);
acl-permit? is unaffected. 145/145.

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

lib/acl/audit.sx

@@ -3,12 +3,23 @@
 ;; Every decision routed through acl-audit-decide! is appended to an in-memory
 ;; log with a monotonic sequence number (no wall-clock — deterministic and
 ;; testable; a host can stamp time at the serializer boundary). The log is
-;; append-only: there is no mutate or delete, only append, tail, clear, and
+;; append-only: there is no mutate or delete, only append, tail, clear,
-;; serialize-for-disk.
+;; snapshot/restore, and serialize-for-disk.
 
 (define acl-audit-log (list))
 (define acl-audit-seq 0)
 
+;; Copy a list into a fresh, append!-able list. `map`/`rest`-derived lists are
+;; NOT extensible by append! in this runtime (it silently no-ops), so the live
+;; log must always be a list built with `list` + `append!`.
+(define
+  acl-audit-copy
+  (fn
+    (xs)
+    (let
+      ((fresh (list)))
+      (do (for-each (fn (e) (append! fresh e)) xs) fresh))))
+
 (define
   acl-audit-clear!
   (fn
@@ -57,8 +68,25 @@
     (xs k)
     (if (<= k 0) xs (acl-audit-drop (rest xs) (- k 1)))))
 
+;; Structured snapshot for save/restore — a {:seq :entries} value carrying a
+;; copy of the log (so later appends don't mutate a held snapshot).
+(define acl-audit-snapshot (fn () {:seq acl-audit-seq :entries (acl-audit-copy acl-audit-log)}))
+
+;; Replace the live log from a snapshot. Restores both entries and the seq
+;; counter so subsequent records continue numbering correctly. The log is
+;; rebuilt as a fresh append!-able list (see acl-audit-copy).
+(define
+  acl-audit-restore!
+  (fn
+    (snap)
+    (do
+      (set! acl-audit-log (acl-audit-copy (get snap :entries)))
+      (set! acl-audit-seq (get snap :seq))
+      nil)))
+
 ;; Serialize the whole log to a disk-ready string: one record per line,
-;; "seq\tsubj\tact\tres\tallowed?". A host writes this; reload is out of scope.
+;; "seq\tsubj\tact\tres\tallowed?". A host writes this; structured reload is via
+;; snapshot/restore.
 (define
   acl-audit-serialize
   (fn

lib/acl/conformance.conf

@@ -28,4 +28,5 @@ SUITES=(
   "inherit:lib/acl/tests/inherit.sx:(acl-inherit-tests-run!)"
   "explain:lib/acl/tests/explain.sx:(acl-explain-tests-run!)"
   "fed:lib/acl/tests/fed.sx:(acl-fed-tests-run!)"
+  "harden:lib/acl/tests/harden.sx:(acl-harden-tests-run!)"
 )

lib/acl/schema.sx

@@ -50,3 +50,22 @@
         (and
           (has-key? acl-edb-arity pred)
           (= (- (len f) 1) (get acl-edb-arity pred)))))))
+
+;; Return the sublist of facts that fail acl-fact-valid?. Empty list means the
+;; whole set is well-formed. acl-build-db stays lenient (Datalog accepts any
+;; tuple, and custom action symbols are allowed); callers opt in to checking.
+(define
+  acl-validate-facts
+  (fn
+    (facts)
+    (let
+      ((bad (list)))
+      (do
+        (for-each
+          (fn (f) (when (not (acl-fact-valid? f)) (append! bad f)))
+          facts)
+        bad))))
+
+(define
+  acl-facts-valid?
+  (fn (facts) (= (len (acl-validate-facts facts)) 0)))

lib/acl/scoreboard.json

@@ -1,13 +1,14 @@
 {
   "lang": "acl",
-  "total_passed": 120,
+  "total_passed": 145,
   "total_failed": 0,
-  "total": 120,
+  "total": 145,
   "suites": [
     {"name":"direct","passed":24,"failed":0,"total":24},
     {"name":"inherit","passed":30,"failed":0,"total":30},
     {"name":"explain","passed":35,"failed":0,"total":35},
-    {"name":"fed","passed":31,"failed":0,"total":31}
+    {"name":"fed","passed":31,"failed":0,"total":31},
+    {"name":"harden","passed":25,"failed":0,"total":25}
   ],
-  "generated": "2026-06-06T16:53:44+00:00"
+  "generated": "2026-06-06T22:43:27+00:00"
 }

lib/acl/scoreboard.md

@@ -1,6 +1,6 @@
 # acl scoreboard
 
-**120 / 120 passing** (0 failure(s)).
+**145 / 145 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -8,3 +8,4 @@
 | inherit | 30 | 30 | ok |
 | explain | 35 | 35 | ok |
 | fed | 31 | 31 | ok |
+| harden | 25 | 25 | ok |

lib/acl/tests/harden.sx

@@ -0,0 +1,228 @@
+;; lib/acl/tests/harden.sx — adversarial / cross-phase hardening.
+;;
+;; Diamond hierarchies, conflict resolution where deny must win through every
+;; path, chain inheritance, cycle termination, multi-peer delegation, fact
+;; validation, and audit save/restore.
+;;
+;; PROVER-FREE BY DESIGN: this suite calls only acl-permit? (which runs in
+;; compiled Datalog, safe at any depth) plus pure data ops — never acl-explain /
+;; acl-prove-d. The SX-side proof reconstructor recurses, and once the kernel
+;; JIT-compiles it (after the explain/fed suites warm the process) it loops on
+;; chains deeper than ~3 (substrate JIT bug — see plan Blockers). Proof
+;; reconstruction is covered by tests/explain.sx (and federated proofs by
+;; tests/fed.sx), both of which stay under the warm-process depth threshold.
+
+(define acl-hd-pass 0)
+(define acl-hd-fail 0)
+(define acl-hd-failures (list))
+
+(define
+  acl-hd-check!
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! acl-hd-pass (+ acl-hd-pass 1))
+      (do
+        (set! acl-hd-fail (+ acl-hd-fail 1))
+        (append!
+          acl-hd-failures
+          (str name "\n    expected: " expected "\n    got:      " got))))))
+
+(define acl-hd-p? (fn (db s a r) (acl-permit? db s a r)))
+
+(define
+  acl-hd-run-all!
+  (fn
+    ()
+    (do
+      (let
+        ((grant-deny (acl-build-db (list (acl-child-of (quote r) (quote p1)) (acl-child-of (quote r) (quote p2)) (acl-grant (quote u) (quote read) (quote p1)) (acl-deny (quote u) (quote read) (quote p2)))))
+          (both-grant
+            (acl-build-db
+              (list
+                (acl-child-of (quote r) (quote p1))
+                (acl-child-of (quote r) (quote p2))
+                (acl-grant (quote u) (quote read) (quote p1))
+                (acl-grant (quote u) (quote read) (quote p2))))))
+        (do
+          (acl-hd-check!
+            "diamond resource: grant+deny parents -> deny wins"
+            (acl-hd-p? grant-deny (quote u) (quote read) (quote r))
+            false)
+          (acl-hd-check!
+            "diamond resource: both grant -> permit"
+            (acl-hd-p? both-grant (quote u) (quote read) (quote r))
+            true)
+          (acl-hd-check!
+            "diamond resource: deny does not leak to other parent"
+            (acl-hd-p? grant-deny (quote u) (quote read) (quote p1))
+            true)))
+      (let
+        ((grant-deny (acl-build-db (list (acl-member-of (quote alice) (quote g1)) (acl-member-of (quote alice) (quote g2)) (acl-grant (quote g1) (quote read) (quote doc)) (acl-deny (quote g2) (quote read) (quote doc)))))
+          (both-grant
+            (acl-build-db
+              (list
+                (acl-member-of (quote alice) (quote g1))
+                (acl-member-of (quote alice) (quote g2))
+                (acl-grant (quote g1) (quote read) (quote doc))
+                (acl-grant (quote g2) (quote read) (quote doc))))))
+        (do
+          (acl-hd-check!
+            "diamond group: grant+deny groups -> deny wins"
+            (acl-hd-p? grant-deny (quote alice) (quote read) (quote doc))
+            false)
+          (acl-hd-check!
+            "diamond group: both grant -> permit"
+            (acl-hd-p? both-grant (quote alice) (quote read) (quote doc))
+            true)))
+      (let
+        ((chain (acl-build-db (list (acl-member-of (quote a0) (quote a1)) (acl-member-of (quote a1) (quote a2)) (acl-member-of (quote a2) (quote a3)) (acl-member-of (quote a3) (quote a4)) (acl-grant (quote a4) (quote read) (quote res)))))
+          (chain-deny
+            (acl-build-db
+              (list
+                (acl-member-of (quote a0) (quote a1))
+                (acl-member-of (quote a1) (quote a2))
+                (acl-member-of (quote a2) (quote a3))
+                (acl-member-of (quote a3) (quote a4))
+                (acl-grant (quote a4) (quote read) (quote res))
+                (acl-deny (quote a0) (quote read) (quote res))))))
+        (do
+          (acl-hd-check!
+            "chain: top-group grant reaches leaf member"
+            (acl-hd-p? chain (quote a0) (quote read) (quote res))
+            true)
+          (acl-hd-check!
+            "chain: intermediate also covered"
+            (acl-hd-p? chain (quote a2) (quote read) (quote res))
+            true)
+          (acl-hd-check!
+            "chain: leaf-member deny overrides top grant"
+            (acl-hd-p? chain-deny (quote a0) (quote read) (quote res))
+            false)
+          (acl-hd-check!
+            "chain: deny on leaf does not block sibling level"
+            (acl-hd-p? chain-deny (quote a1) (quote read) (quote res))
+            true)))
+      (let
+        ((self-member (acl-build-db (list (acl-member-of (quote a) (quote a)) (acl-grant (quote a) (quote read) (quote r)))))
+          (self-child
+            (acl-build-db
+              (list
+                (acl-child-of (quote r) (quote r))
+                (acl-grant (quote u) (quote read) (quote r)))))
+          (two-cycle
+            (acl-build-db
+              (list
+                (acl-member-of (quote x) (quote y))
+                (acl-member-of (quote y) (quote x))
+                (acl-grant (quote y) (quote read) (quote r))))))
+        (do
+          (acl-hd-check!
+            "self-membership cycle terminates and grants"
+            (acl-hd-p? self-member (quote a) (quote read) (quote r))
+            true)
+          (acl-hd-check!
+            "self-child cycle terminates and grants"
+            (acl-hd-p? self-child (quote u) (quote read) (quote r))
+            true)
+          (acl-hd-check!
+            "two-node membership cycle terminates"
+            (acl-hd-p? two-cycle (quote x) (quote read) (quote r))
+            true)))
+      (let
+        ((db (acl-build-db (list (acl-trust (quote alpha) (quote full)) (acl-level-covers (quote full) (quote read)) (acl-member-of (quote alice) (quote team)) (acl-delegate (quote alpha) (quote team) (quote read) (quote doc)) (acl-deny (quote alice) (quote read) (quote doc))))))
+        (acl-hd-check!
+          "federated group grant, local member deny -> deny wins"
+          (acl-hd-p? db (quote alice) (quote read) (quote doc))
+          false))
+      (let
+        ((db (acl-build-db (list (acl-trust (quote alpha) (quote full)) (acl-level-covers (quote full) (quote read)) (acl-delegate (quote alpha) (quote bob) (quote read) (quote doc)) (acl-delegate (quote beta) (quote bob) (quote read) (quote doc))))))
+        (acl-hd-check!
+          "two peers delegate, one trusted -> permit"
+          (acl-hd-p? db (quote bob) (quote read) (quote doc))
+          true))
+      (let
+        ((db (acl-build-db (list (acl-trust (quote alpha) (quote full)) (acl-trust (quote beta) (quote full)) (acl-level-covers (quote full) (quote read)) (acl-delegate (quote alpha) (quote bob) (quote read) (quote doc)) (acl-delegate (quote beta) (quote bob) (quote read) (quote doc))))))
+        (acl-hd-check!
+          "two peers both trusted -> permit"
+          (acl-hd-p? db (quote bob) (quote read) (quote doc))
+          true))
+      (let
+        ((empty (acl-build-db (list))))
+        (acl-hd-check!
+          "empty db: nothing permitted"
+          (acl-hd-p? empty (quote u) (quote read) (quote r))
+          false))
+      (do
+        (acl-hd-check!
+          "validate: clean set has no bad facts"
+          (len
+            (acl-validate-facts
+              (list
+                (acl-grant (quote u) (quote read) (quote p))
+                (acl-member-of (quote u) (quote g))
+                (acl-delegate (quote pe) (quote u) (quote read) (quote p)))))
+          0)
+        (acl-hd-check!
+          "validate: facts-valid? true on clean set"
+          (acl-facts-valid?
+            (list (acl-grant (quote u) (quote read) (quote p))))
+          true)
+        (acl-hd-check!
+          "validate: surfaces wrong-arity and unknown predicate"
+          (len
+            (acl-validate-facts
+              (list
+                (acl-grant (quote u) (quote read) (quote p))
+                (list (quote grant) (quote u))
+                (list (quote bogus) (quote x) (quote y)))))
+          2)
+        (acl-hd-check!
+          "validate: empty set is valid"
+          (acl-facts-valid? (list))
+          true))
+      (let
+        ((db (acl-build-db (list (acl-grant (quote u) (quote read) (quote p)) (acl-deny (quote u) (quote edit) (quote p))))))
+        (do
+          (acl-audit-clear!)
+          (acl-audit-decide! db (quote u) (quote read) (quote p))
+          (acl-audit-decide! db (quote u) (quote edit) (quote p))
+          (let
+            ((snap (acl-audit-snapshot)))
+            (do
+              (acl-audit-clear!)
+              (acl-hd-check!
+                "audit: cleared count is 0"
+                (acl-audit-count)
+                0)
+              (acl-audit-restore! snap)
+              (acl-hd-check!
+                "audit: restored count"
+                (acl-audit-count)
+                2)
+              (acl-hd-check!
+                "audit: restored last act"
+                (get (first (acl-audit-tail 1)) :act)
+                (quote edit))
+              (acl-audit-decide! db (quote u) (quote comment) (quote p))
+              (acl-hd-check!
+                "audit: seq continues after restore"
+                (get (first (acl-audit-tail 1)) :seq)
+                2)
+              (acl-hd-check!
+                "audit: snapshot is an immutable copy"
+                (len (get snap :entries))
+                2)
+              (acl-audit-clear!))))))))
+
+(define
+  acl-harden-tests-run!
+  (fn
+    ()
+    (do
+      (set! acl-hd-pass 0)
+      (set! acl-hd-fail 0)
+      (set! acl-hd-failures (list))
+      (acl-hd-run-all!)
+      {:failures acl-hd-failures :total (+ acl-hd-pass acl-hd-fail) :passed acl-hd-pass :failed acl-hd-fail})))

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` → **120/120** (all four phases complete)
+`bash lib/acl/conformance.sh` → **145/145** (all four phases + hardening)
 
 ## Ground rules
 
@@ -224,6 +224,58 @@ One engine rule carries federation:
     forms. `sx_write_file`, `sx_validate`, `sx_find_all`, `sx_summarise`,
     `sx_eval` all work; used full-file rewrites instead of path edits throughout.
 
+## Hardening (post-roadmap)
+
+- **`lib/acl/tests/harden.sx` (+25).** Adversarial / cross-phase coverage beyond
+  the per-phase suites. **Prover-free by design** (see JIT blocker below): only
+  `acl-permit?` (compiled Datalog, safe at any depth) + pure data ops, never
+  `acl-explain`/`acl-prove-d`.
+  - Diamond hierarchies (resource and group): grant on one path + deny on
+    another → deny wins; both-grant → permit; deny does not leak to siblings.
+  - Chain inheritance (literal 4-link): top-group grant reaches leaf member and
+    intermediates; leaf-member deny overrides the top grant; deny on the leaf
+    doesn't block a higher level.
+  - Cycle termination: self-membership, self-child, and 2-node membership cycles
+    all reach a fixpoint and decide correctly.
+  - Federation conflicts: federated group-grant with a locally-denied member →
+    deny; multi-peer delegation (one trusted, or both trusted) → permit.
+  - Degenerate inputs: empty db permits nothing.
+  - Fact validation: `acl-validate-facts` surfaces wrong-arity + unknown
+    predicates; `acl-facts-valid?` on clean/empty sets.
+  - Audit save/restore: snapshot → clear → restore round-trips entries + seq;
+    seq continues without collision after restore; snapshot is an immutable copy.
+  - Proof reconstruction itself is covered by tests/explain.sx + tests/fed.sx
+    (both stay under the warm-process JIT depth threshold); the depth-cap safety
+    net is verified manually in a warm REPL image but excluded from conformance.
+- **New API:** `acl-validate-facts`/`acl-facts-valid?` (schema.sx, opt-in — build
+  stays lenient); `acl-audit-snapshot`/`acl-audit-restore!`/`acl-audit-copy`
+  (audit.sx).
+- **Substrate gotcha (recorded):** `append!` extends a list built with `(list)`
+  but **silently no-ops on a `map`/`rest`-derived list** in this runtime. Bit the
+  first cut of `acl-audit-restore!` (rebuilt the live log via `map`, so later
+  records didn't append). Fix: always rebuild mutable lists via `(list)` +
+  `append!` (`acl-audit-copy`). Worth flagging to kernel owners; out of acl scope.
+
 ## Blockers
 
-(loop fills this in)
+- **JIT loops on deep proof reconstruction (substrate, not acl).** Once the
+  kernel JIT-compiles the mutually-recursive prover (`acl-prove-d`/
+  `acl-prove-rules`/`acl-prove-build` in `explain.sx`) — which happens after a
+  process has run enough explains to cross the compile threshold — the compiled
+  version **loops indefinitely** on a `member_of`/`child_of` chain deeper than
+  ~3. Symptoms: `acl-explain` over a 4+-deep chain returns instantly in a cold /
+  warm-REPL image but **hangs** in a long-lived process. The per-phase explain
+  and fed suites pass only because their proofs stay ≤3 deep; a 5th suite that
+  explained deeper chains hung the whole conformance run (no per-suite timeout
+  in dict mode). Matches `[[project_jit_bytecode_bug]]` (ACTIVE).
+  - *Impact beyond tests:* `acl-explain` is unsafe for deep hierarchies in a
+    warm production OCaml server. `acl-permit?` is unaffected (it reduces to
+    compiled Datalog, no SX-side recursion) — only the SX proof reconstructor is.
+  - *Workaround in acl:* harden suite is prover-free; explain is exercised only
+    at shallow depth. *Real fix is in the kernel JIT* (out of acl scope) — e.g.
+    the `_jit_compiling` guard / disabling JIT for the recursive prover, or
+    fixing the bytecode loop. Recommend the kernel owners reproduce with:
+    `acl-explain` over a 6-deep `member_of` chain after ~70 prior explains.
+  - *Minimal repro recorded.* Until fixed, callers needing explanations for
+    deep hierarchies should flatten or cap depth, or run explain in a cold
+    worker.