diff --git a/lib/lua/runtime.sx b/lib/lua/runtime.sx
index 68c70de6..28f0b23f 100644
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -730,14 +730,76 @@
 
 ;; Match a single "pattern atom" (char or class) at src position — returns true or false.
 ;; pat-pos is position of the atom start. Returns the atom's length in pat (1 or 2).
+(define
+  lua-pat-set-end
+  (fn (pat pat-pos)
+    (let ((i (+ pat-pos 1)))
+      (begin
+        (when (and (< i (len pat)) (= (char-at pat i) "^"))
+          (set! i (+ i 1)))
+        (when (and (< i (len pat)) (= (char-at pat i) "]"))
+          (set! i (+ i 1)))
+        (define
+          se-loop
+          (fn ()
+            (when (< i (len pat))
+              (let ((c (char-at pat i)))
+                (cond
+                  ((= c "]") nil)
+                  ((= c "%")
+                    (begin (set! i (+ i 2)) (se-loop)))
+                  (else
+                    (begin (set! i (+ i 1)) (se-loop))))))))
+        (se-loop)
+        i))))
+
 (define
   lua-pat-atom-len
   (fn (pat pat-pos)
     (cond
       ((>= pat-pos (len pat)) 0)
       ((= (char-at pat pat-pos) "%") 2)
+      ((= (char-at pat pat-pos) "[")
+        (let ((end (lua-pat-set-end pat pat-pos)))
+          (- (+ end 1) pat-pos)))
       (else 1))))
 
+(define
+  lua-pat-set-match
+  (fn (pat set-start sc)
+    (let ((i (+ set-start 1)) (negated false) (matched false))
+      (begin
+        (when (and (< i (len pat)) (= (char-at pat i) "^"))
+          (begin (set! negated true) (set! i (+ i 1))))
+        (define
+          sm-loop
+          (fn ()
+            (when (and (< i (len pat)) (not (= (char-at pat i) "]")))
+              (let ((c (char-at pat i)))
+                (cond
+                  ((= c "%")
+                    (cond
+                      ((< (+ i 1) (len pat))
+                        (begin
+                          (when (lua-pat-class-match (char-at pat (+ i 1)) sc)
+                            (set! matched true))
+                          (set! i (+ i 2))
+                          (sm-loop)))
+                      (else (set! i (+ i 1)))))
+                  ((and (< (+ i 2) (len pat)) (= (char-at pat (+ i 1)) "-") (not (= (char-at pat (+ i 2)) "]")))
+                    (begin
+                      (when (and (>= sc c) (<= sc (char-at pat (+ i 2))))
+                        (set! matched true))
+                      (set! i (+ i 3))
+                      (sm-loop)))
+                  (else
+                    (begin
+                      (when (= sc c) (set! matched true))
+                      (set! i (+ i 1))
+                      (sm-loop))))))))
+        (sm-loop)
+        (if negated (not matched) matched)))))
+
 (define
   lua-pat-atom-match
   (fn (pat pat-pos s s-pos)
@@ -752,6 +814,7 @@
               (cond
                 ((>= (+ pat-pos 1) (len pat)) false)
                 (else (lua-pat-class-match (char-at pat (+ pat-pos 1)) sc))))
+            ((= pc "[") (lua-pat-set-match pat pat-pos sc))
             (else (= pc sc))))))))
 
 ;; Match pattern against string starting at s-pos and pat-pos. Returns end-pos (inclusive+1) or -1 on no-match.
diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index 8a6acc38..8a4dae70 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "totals": {
     "pass": 1,
-    "fail": 11,
-    "timeout": 4,
+    "fail": 8,
+    "timeout": 7,
     "skip": 8,
     "total": 24,
     "runnable": 16,
@@ -10,11 +10,11 @@
   },
   "top_failure_modes": [
     [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      6
+      "timeout",
+      7
     ],
     [
-      "timeout",
+      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
       4
     ],
     [
@@ -28,10 +28,6 @@
     [
       "undefined symbol: fat\\",
       1
-    ],
-    [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
-      1
     ]
   ],
   "results": [
@@ -51,7 +47,7 @@
       "name": "attrib.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: module 'C' not found\\\\\\\"\\",
-      "ms": 6133
+      "ms": 6895
     },
     {
       "name": "big.lua",
@@ -63,7 +59,7 @@
       "name": "calls.lua",
       "status": "fail",
       "reason": "undefined symbol: fat\\",
-      "ms": 5786
+      "ms": 5736
     },
     {
       "name": "checktable.lua",
@@ -75,7 +71,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8008
+      "ms": 8007
     },
     {
       "name": "code.lua",
@@ -85,9 +81,9 @@
     },
     {
       "name": "constructs.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
-      "ms": 7418
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8008
     },
     {
       "name": "db.lua",
@@ -99,13 +95,13 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4168
+      "ms": 3826
     },
     {
       "name": "events.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 7884
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8007
     },
     {
       "name": "files.lua",
@@ -123,13 +119,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 1796
+      "ms": 2748
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 1655
+      "ms": 2339
     },
     {
       "name": "main.lua",
@@ -141,7 +137,7 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 5457
+      "ms": 6042
     },
     {
       "name": "nextvar.lua",
@@ -151,33 +147,33 @@
     },
     {
       "name": "pm.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6576
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8010
     },
     {
       "name": "sort.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8008
+      "ms": 8007
     },
     {
       "name": "strings.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4708
+      "ms": 6167
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2227
+      "ms": 3432
     },
     {
       "name": "verybig.lua",
       "status": "pass",
       "reason": "",
-      "ms": 959
+      "ms": 1659
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 9612c3aa..5dab9f84 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -1,16 +1,15 @@
 # Lua-on-SX conformance scoreboard
 
 **Pass rate:** 1/16 runnable (6.2%)
-fail=11 timeout=4 skip=8 total=24
+fail=8 timeout=7 skip=8 total=24
 
 ## Top failure modes
 
-- **6x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
-- **4x** timeout
+- **7x** timeout
+- **4x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
 - **2x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio
 - **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\
 - **1x** undefined symbol: fat\
-- **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat
 
 ## Per-test results
 
@@ -18,25 +17,25 @@ fail=11 timeout=4 skip=8 total=24
 |---|---|---|---:|
 | all.lua | skip | driver uses dofile to chain other tests | 0 |
 | api.lua | skip | requires testC (C debug library) | 0 |
-| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6133 |
+| attrib.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: module 'C' not found\\\"\ | 6895 |
 | big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | undefined symbol: fat\ | 5786 |
+| calls.lua | fail | undefined symbol: fat\ | 5736 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8008 |
+| closure.lua | timeout | per-test timeout | 8007 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
-| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat | 7418 |
+| constructs.lua | timeout | per-test timeout | 8008 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4168 |
-| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7884 |
+| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3826 |
+| events.lua | timeout | per-test timeout | 8007 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 1796 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1655 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2748 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 2339 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 5457 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 6042 |
 | nextvar.lua | timeout | per-test timeout | 8007 |
-| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6576 |
-| sort.lua | timeout | per-test timeout | 8008 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4708 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2227 |
-| verybig.lua | pass | - | 959 |
+| pm.lua | timeout | per-test timeout | 8010 |
+| sort.lua | timeout | per-test timeout | 8007 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6167 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3432 |
+| verybig.lua | pass | - | 1659 |
diff --git a/lib/lua/test.sh b/lib/lua/test.sh
index deebeb57..bc846a73 100755
--- a/lib/lua/test.sh
+++ b/lib/lua/test.sh
@@ -986,6 +986,14 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1902)
 (eval "(lua-eval-ast \"if tonumber('99', 8) == nil then return 1 else return 0 end\")")
 
+;; ── Pattern character sets [...] ──────────────────────────────
+(epoch 1910)
+(eval "(lua-eval-ast \"return string.match(\\\"hello123\\\", \\\"[a-z]+\\\")\")")
+(epoch 1911)
+(eval "(lua-eval-ast \"return string.match(\\\"hello123\\\", \\\"[0-9]+\\\")\")")
+(epoch 1912)
+(eval "(lua-eval-ast \"return string.match(\\\"abc\\\", \\\"[^a]+\\\")\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1495,6 +1503,11 @@ check 1900 "tonumber('1010', 2)"            '10'
 check 1901 "tonumber('FF', 16)"             '255'
 check 1902 "tonumber('99', 8) → nil"        '1'
 
+# ── Pattern character sets [...] ─────────────────────────────
+check 1910 "[a-z]+ on hello123"             '"hello"'
+check 1911 "[0-9]+ on hello123"             '"123"'
+check 1912 "[^a]+ on abc"                   '"bc"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL Lua-on-SX tests passed"
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 879b0e15..6f76ba17 100644
--- a/plans/lua-on-sx.md
+++ b/plans/lua-on-sx.md
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-24: lua: scoreboard iteration — **pattern character sets** `[...]` and `[^...]`. New `lua-pat-set-end`/`lua-pat-set-match` helpers handle ranges (`[a-z]`), classes inside sets (`[%d%a]`), negation (`[^abc]`), and `[]...]`/`[^]...]` (literal `]` as first char). Asserts 6→4, but timeouts 3→7 — many tests now reach loop-heavy code. 387/387 green (+3 charset tests).
 - 2026-04-24: lua: scoreboard iteration — `tonumber(s, base)` for bases 2-36. Validates digit ranges per base, supports leading `+`/`-`, trims whitespace. `math.lua` past assert #21. Asserts 8→6, timeouts 3→4. 384/384 green.
 - 2026-04-24: lua: scoreboard iteration — added `lua-unwrap-final-return` (post-processor that rewrites top-level `(raise (list 'lua-ret V))` → `V` so top-level defines leak to SX top and loadstring closures can see them). Tried dropping the function-guard at top level, but too many tests use `if x then return 0 else return err end` at chunk tail, whose returns aren't at the *statement-list* tail — guard still needed. Kept guard + unwrap-as-no-op. Scoreboard unchanged.
 - 2026-04-24: lua: scoreboard iteration — `lua-pat-strip-captures` helper lets patterns with `(...)` capture parens at least match (captures themselves aren't returned yet — match returns whole match). Unblocks common Lua pattern idioms like `(%a+)=(%d+)`. Scoreboard unchanged.