adityamukho · Nov 4, 2026 · Nov 4, 2026
@@ -147,8 +147,10 @@ The #723 ancestor tests also cover empty deltas, the 128-row demand cap, the eig
 The evaluator fuzz guard has a separate regression suite in
 `fuzz/tests/datalog_eval_guard.rs`, run by the nightly fuzz workflow. It checks
 scope isolation, join-variable declarations, selective joins and cross-product
-rejection, including the timeout input from #802. These harness-only tests are
-not included in the engine test count. Run them without building the engine:
+rejection, including the timeout input from #802 and all three artifacts from #835.
+The #835 cases cover EDN comma separators, adjacent symbol/keyword tokens,
+and the per-visible-fact multiplication of `:db/valid-at` patterns. These
+harness-only tests are not included in the engine test count. Run them without building the engine:
 
 ```bash
 rustc --edition=2021 --test fuzz/tests/datalog_eval_guard.rs -o /tmp/datalog-eval-guard-tests

@@ -19,7 +19,8 @@ pub(crate) const MAX_JOIN_ROWS: u64 = 50_000;
 /// independently or once per outer binding: outer constraints must not shrink
 /// their estimate (#802). Each group's join is counted against `FACTS`, and the
 /// groups multiply, including groups in different scopes. Join-variable declaration
-/// vectors are excluded because they are not fact patterns.
+/// vectors are excluded because they are not fact patterns. `:db/valid-at`
+/// scans are counted as `[entity _ _]`, one row per visible fact (#835).
 /// A group with no matches counts as 1, so an empty pattern never hides a cross
 /// product that the planner may build before reaching it.
 pub(crate) fn join_rows_bound(s: &str) -> u64 {
@@ -100,11 +101,18 @@ fn patterns(s: &str) -> Vec<(usize, [&str; 3])> {
             }
             ']' => {
                 if let Some((from, scope)) = start.take() {
-                    let mut tokens = s[from..i].split_whitespace();
+                    let mut tokens = pattern_tokens(&s[from..i]);
                     if let (Some(e), Some(a), Some(v)) =
                         (tokens.next(), tokens.next(), tokens.next())
                     {
-                        out.push((scope, [e, a, v]));
+                        // Valid-at scans every visible fact of the entity; its
+                        // value is query metadata, not the stored fact's value.
+                        let p = if a == ":db/valid-at" {
+                            [e, "_", "_"]
+                        } else {
+                            [e, a, v]
+                        };
+                        out.push((scope, p));
                     }
                 }
             }
@@ -114,6 +122,42 @@ fn patterns(s: &str) -> Vec<(usize, [&str; 3])> {
     out
 }
 
+/// Lex the pattern's atoms without requiring whitespace between a symbol and
+/// keyword/string. EDN commas separate tokens, including before a variable
+/// (#835). Keep strings whole so their contents cannot become join variables.
+fn pattern_tokens(mut s: &str) -> impl Iterator<Item = &str> {
+    std::iter::from_fn(move || {
+        s = s.trim_start_matches(|c: char| c.is_whitespace() || c == ',');
+        if s.is_empty() {
+            return None;
+        }
+        let mut end = s.len();
+        if s.starts_with('"') {
+            let mut escaped = false;
+            for (i, c) in s.char_indices().skip(1) {
+                if escaped {
+                    escaped = false;
+                } else if c == '\\' {
+                    escaped = true;
+                } else if c == '"' {
+                    end = i + 1;
+                    break;
+                }
+            }
+        } else {
+            for (i, c) in s.char_indices().skip(1) {
+                if c.is_whitespace() || matches!(c, ',' | ':' | '"') {
+                    end = i;
+                    break;
+                }
+            }
+        }
+        let (token, rest) = s.split_at(end);
+        s = rest;
+        Some(token)
+    })
+}
+
 fn is_wildcard(t: &str) -> bool {
     t == "_" || t.starts_with("?_")
 }

@@ -76,3 +76,44 @@ fn sibling_branches_have_separate_scopes() {
         2
     );
 }
+
+#[test]
+fn rejects_issue_835_artifacts() {
+    for input in [
+        include_str!("fixtures/835-slow.edn"),
+        include_str!("fixtures/835-slow-2.edn"),
+        include_str!("fixtures/835-timeout.edn"),
+    ] {
+        assert!(join_rows_bound(input) > MAX_JOIN_ROWS);
+    }
+}
+
+#[test]
+fn commas_do_not_hide_expanding_joins() {
+    let input = format!(
+        "[?e ?a ,?v] {}",
+        (0..16)
+            .map(|i| format!("[?e ?a{i} ?v{i}] "))
+            .collect::<String>()
+    );
+    assert!(join_rows_bound(&input) > MAX_JOIN_ROWS);
+}
+
+#[test]
+fn valid_at_patterns_multiply_visible_facts() {
+    for pattern in ["[?e :db/valid-at ?t] ", "[?e:db/valid-at ?t] "] {
+        let input = format!("[?e :age ?v] {}", pattern.repeat(16));
+        assert!(join_rows_bound(&input) > MAX_JOIN_ROWS);
+    }
+}
+
+#[test]
+fn separators_preserve_selective_pattern_counts() {
+    for input in ["[?e,:name,?v]", "[?e:name ?v]"] {
+        assert_eq!(join_rows_bound(input), 2);
+    }
+    assert_eq!(join_rows_bound(r#"[?e:name"Alice"]"#), 1);
+    assert_eq!(join_rows_bound("[?e:db/valid-at ?t]"), 3);
+    assert_eq!(join_rows_bound(r#"[_ _ "Alice, :name ?e"]"#), 1);
+    assert_eq!(join_rows_bound(r#"[_ _ "Alice\", :name ?e"]"#), 1);
+}
@@ -0,0 +1 @@
+(query [:find ?n :where [?e ?nmjFqfnEEufn ?a]  [?e ?ynsfzun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ,?c]  [?e ?nynEEEEEEEFEEhEEEEEEEEEEEEqfn ?cfalse]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ?c]  [?e ?nynEEEEEEEFEEhEEqfn ?g]  [?e ?lynufn ?q]  [?e ?lynnueFF-nnyneFFFufn ?s]  [?e ?lynnue ?]  [?e ?l3fn ?k ] [?d ?lynEEEGEEMEAEOEEufn ?aUUUUUUUUUUUUUUUUUUUUUUU]  [?0e ?ynstfun ?h]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueF1EEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue00000EEqfn ?c]  [?_?e ?lysnun ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNN?l?nn?eqfnNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNN]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ?c]  [?e ?nynEEEEEEEFEEhEEqfn ?g]  [?e ?lynufn ?q]  [?e ?lynnueFF-nnyneFFFufn ?s]  [?e ?lynnue ?]  [?e ?l3fn ?k ] [?d ? ?aUUUUUUUUUUUUUUUUUUUUUUU]  [?0e ?ynsufun ?h]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueF1EEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue0000000sufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue000000sufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEfn ?c]  [?e ?lynnueFFnrue666666666nufn ?Sc]  [?e ?lynnueFFnnue000000001306772764176710315e ?n] [(>=?n "e")]])

@@ -0,0 +1 @@
+(query [:find ?n :where [?e ?nmjFqfnEEufn ?a]  [?e ?ynsfzun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ,?c]  [?e ?nynEEEEEEEFEEhEEEEEEEEEEEEqfn ?cfalse]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ?c]  [?e ?nynEEEEEEEFEEhEEqfn ?g]  [?e ?lynufn ?q]  [?e ?lynnueFF-nnyneFFFufn ?s]  [?e ?lynnue ?]  [?e ?l3fn ?k ] [?d ?lynEEEGEEMEAEOEEufn ?aUUUUUUUUUUUUUUUUUUUUUUU]  [?0e ?ynstfun ?h]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueF1EEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue00000EEqfn ?c]  [?_?e ?lysnun ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNN?l?nn?eqfnNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNN]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?lu?ueFEEEEEEEEEEEqfn ?c]  [?_?e ?ljFqfn ?c]  [?e ?nynEEEEEEEFEEhEEqfn ?g]  [?e ?lynufn ?q]  [?e ?lynnueFF-nnyneFFFufn ?s]  [?e ?lynnue ?]  [?e ?l3fn ?k ] [?d ? ?aUUUUUUUUUUUUUUUUUUUUUUU]  [?0e ?ynsufun ?h]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEEEEn ?cor-join]  [?_?e ?lysnufnc ?]  [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a]  [?e ?ynsufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueF1EEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue0000000sufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue000000sufun ?c]  [?e ?lunufn ?a]  [?e ?lynnueFFnnueFEEEEfn ?c]  [?e ?lynnueFFnnue666666666nufn ?Sc]  [?e ?lynnueFFnnue000000001306772764176710315e ?n] [(>=?n "e")]])

@@ -0,0 +1,15 @@
+(query [:find ?n :where [?e ?nmjFqfn ?y]  [?e ?nynEEEEEEEEEEEEEEEEqfcn  ?] [?_?e ?lysnufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznufn ?c]  [?e ?lunufn ?c]  [?e ?lynnu875nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEEEd?eEEqfn ?k?g]
+ [?e ?lynnfnqfn ?y]  [?e ?nynEEEEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznufn ?c]  [?e ?lunufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznEEEEEEEqfcn  ?] [?_?e ?lysnufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznufn ?c]  [?e ?lunufn ?c]  [?e ?lynnu875nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEEEd?eEEqfn ?k?g]
+ [?e ?lynnfnqfn ?y]  [?e ?nynEEEEEEEEEEEEEEqfn ?c]  [?_?e ?lysnufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznufn ?c]  [?e ?lunufn ?c]  [?e ?luEEEEEEEEEEEqfn ?c]  [?_?e ?lyznufn ?c]  [?e ?lunufn ?c]  [?e ?lynnu877nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEEEdEEqn?fe ?k?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?g?e?nEfn ?g]
+ [?e ?lynn ?g]  [?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?nEEEEEEq7nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEd?eEEqfn ?k5g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynn ?g]  [?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?ufn ?c]  [?e ?lunufn ?c]  [?e ?lynnu877nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEEEdEEqn?fe ?k?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?g?e?nEfn ?g]
+ [?e ?lynn ?g]  
5618
[?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?nEEEEEEq7nufn ?c]  [?e ?FFFqfn ?k]  [?e ?lynEEEEd?eEEq?lynEEd?eEEqfn ?k5g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynn ?g]  [?e:db/valid-at ?s]  [?e ?nEfn ?g]
+ [?e ?lynnfn ?g]  [?e:db/valid-at ?s]  [?e ?nEEEEEEqff ?c]  [?_?e ?3e ?n] [(>=?n "e")]])
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		(query [:find ?n :where [?e ?nmjFqfnEEufn ?a] [?e ?ynsfzun ?c] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c] [?_?e ?lysnufn ?c] [?e ?lu?ueFEEEEEEEEEEEqfn ?c] [?_?e ?ljFqfn ,?c] [?e ?nynEEEEEEEFEEhEEEEEEEEEEEEqfn ?cfalse] [?_?e ?lysnufn ?c] [?e ?lu?ueFEEEEEEEEEEEqfn ?c] [?_?e ?ljFqfn ?c] [?e ?nynEEEEEEEFEEhEEqfn ?g] [?e ?lynufn ?q] [?e ?lynnueFF-nnyneFFFufn ?s] [?e ?lynnue ?] [?e ?l3fn ?k ] [?d ?lynEEEGEEMEAEOEEufn ?aUUUUUUUUUUUUUUUUUUUUUUU] [?0e ?ynstfun ?h] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEEEEn ?cor-join] [?_?e ?lysnufnc ?] [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a] [?e ?ynsufun ?c] [?e ?lunufn ?a] [?e ?lynnueFFnnueF1EEEfn ?c] [?e ?lynnueFFnnue666666666nufn ?Sc] [?e ?lynnueFFnnue00000EEqfn ?c] [?_?e ?lysnun ?c] [?_?e ?lysnufn ?c] [?e ?lu?ueFEEEEEEEEEEEqfn ?c] [?_?e ?ljueFEEEEEEEn ?cor-join] [?_?e ?lysnufnc ?] [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNN?l?nn?eqfnNNNNNNNN?a] [?e ?ynsufun ?c] [?e ?lunufn ?a] [?_?e ?lysnufnc ?] [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNN] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEEEEEEEEqfn ?c] [?_?e ?lysnufn ?c] [?e ?lu?ueFEEEEEEEEEEEqfn ?c] [?_?e ?ljFqfn ?c] [?e ?nynEEEEEEEFEEhEEqfn ?g] [?e ?lynufn ?q] [?e ?lynnueFF-nnyneFFFufn ?s] [?e ?lynnue ?] [?e ?l3fn ?k ] [?d ? ?aUUUUUUUUUUUUUUUUUUUUUUU] [?0e ?ynsufun ?h] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEEEEn ?cor-join] [?_?e ?lysnufnc ?] [?m ?l0m ?n] [(>=?n "e")?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?a] [?e ?ynsufun ?c] [?e ?lunufn ?a] [?e ?lynnueFFnnueF1EEEfn ?c] [?e ?lynnueFFnnue666666666nufn ?Sc] [?e ?lynnueFFnnue0000000sufun ?c] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEfn ?c] [?e ?lynnueFFnnue666666666nufn ?Sc] [?e ?lynnueFFnnue000000sufun ?c] [?e ?lunufn ?a] [?e ?lynnueFFnnueFEEEEfn ?c] [?e ?lynnueFFnrue666666666nufn ?Sc] [?e ?lynnueFFnnue000000001306772764176710315e ?n] [(>=?n "e")]])
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