diff --git a/CHANGELOG.md b/CHANGELOG.md
index d26b31639..31808fbe8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - **Rule queries with a literal argument return every row** (#608). Magic-sets rewriting restricts a rule to the facts its callers demand, but it took each rule's bound arguments from the first call it saw and assumed every other call matched. A call that did not — the same rule called with free arguments elsewhere in the query, a call inside `or` or `not`, a call from a rule the query calls with free arguments, or a rule-body call whose argument nothing bound yet — either failed with `INT-022` (`(chain ?x :c)` with `(chain ?x ?y) :- (link ?x ?m) (chain ?m ?y)`) or silently returned too few rows (`(link ?x :c) (link ?p ?q)` returned only the `:c` edges for `?p ?q`). A query with both arguments literal next to another rule call also lost its rows. The demand on each rule is now the one every call site supplies, and a rule some call site reads in full is evaluated in full. Present since v1.2.0.
+- **A `:db/valid-at` pattern in a `not-join` body binds the query's valid time on every path** (#615). When the body also held an expression, sat in an `or` branch, or ran in a query that invokes a rule, the body bound `nil`, so `(not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)])` never matched and excluded nothing; without the expression the same body excluded every entity. It now binds the query's `:valid-at` value (or the current time) as the other paths do. Present since v0.13.1; v2.x is affected too.
 - **An `or` that shares no variable with the earlier clauses returns its cross product** (#610). Such an `or` — `[?x :edge ?z] (or [?p :edge :b] [?p :edge :c])` — returned no rows when no branch had `not`, `not-join` or a pseudo-attribute, because the incoming rows were replaced by the branch results. Each incoming row now joins every branch row, in queries and rule bodies. `or-join` still refuses a join variable no earlier clause binds (INT-018): it filters, it does not bind.
 - **A prepared query keeps a literal `:as-of`, `:valid-at` or `:any-valid-time`** (#603). Binding a prepared query's slots dropped any `:as-of` or `:valid-at` that was not itself a slot, so `PreparedQuery::execute` and `PreparedQuery::query` ran at the current transaction time and valid now: `(query [:find ?v :as-of 1 :where [:a :n ?v]])` prepared returned the current rows, not those at transaction 1, and a prepared per-fact pseudo-attribute query with `:any-valid-time` failed with `INT-026`. Slot forms (`:as-of $tx`, `:valid-at $t`) were not affected. Present since 2026-04-04; fixed on v2.x too.
 - **The wasm32 builds are tested again, and the browser layer no longer panics or drops pages.** The repo split (#231) moved the browser and WASI CI jobs to minigraf-wasm, which only builds the package, so core's own wasm tests stopped running and the wasm32 test build broke unnoticed. A new `wasm.yml` workflow runs the `wasm-bindgen` tests in headless Firefox and Chrome, runs the unit and integration tests on `wasm32-wasip1` under Wasmtime, and lints both targets with `clippy -D warnings`. Fixes found on the way: `BrowserDb` skipped any dirty page it could not read when flushing to IndexedDB and still reported success, and now returns the error (also fixed in v2.0.4, #470). The IndexedDB upgrade callback, the IndexedDB backend handle and the page-buffer lock no longer `unwrap()` (on wasm32 a panic aborts the whole instance). IndexedDB keys that are not whole page numbers are rejected instead of truncated. The nine `BrowserBufferBackend` tests used `#[test]`, which the wasm test runner never runs, and now run. File-only modules (`wal`, `storage::verify`, `storage::dir_sync`) are no longer compiled for wasm32, so the wasm32 builds have no warnings.
diff --git a/src/query/datalog/evaluator.rs b/src/query/datalog/evaluator.rs
index 6f0aae6fc..43da454de 100644
--- a/src/query/datalog/evaluator.rs
+++ b/src/query/datalog/evaluator.rs
@@ -507,13 +507,15 @@ pub(crate) fn rule_invocation_to_pattern(predicate: &str, args: &[EdnValue]) ->
 ///    - Pattern → substitute join_vars via substitute_pattern.
 ///    - RuleInvocation → convert to Pattern via rule_invocation_to_pattern, then substitute.
 ///      Rule-derived facts are already present in `storage` (accumulated) from lower strata.
-/// 3. Run PatternMatcher::match_patterns on all resulting patterns against `storage`.
+/// 3. Run PatternMatcher::match_patterns on all resulting patterns against `storage`,
+///    with `valid_at` as the value a `:db/valid-at` pattern binds (#615).
 /// 4. Any complete match → body is satisfiable → return true (reject outer binding).
 pub fn evaluate_not_join(
     join_vars: &[String],
     clauses: &[WhereClause],
     binding: &Bindings,
     storage: Arc<[Fact]>,
+    valid_at: Value,
     functions: &FunctionRegistry,
 ) -> bool {
     // Build a partial binding containing only the join variables
@@ -542,7 +544,7 @@ pub fn evaluate_not_join(
         .filter(|c| matches!(c, WhereClause::Expr { .. }))
         .collect();
 
-    let matcher = PatternMatcher::from_slice(storage.clone());
+    let matcher = PatternMatcher::from_slice_with_valid_at(storage.clone(), valid_at);
     let mut not_bindings: Vec<Bindings> = if substituted.is_empty() {
         // Expr-only not-join body: seed with the partial binding so variables resolve.
         vec![partial.clone()]
@@ -985,6 +987,7 @@ impl StratifiedEvaluator {
                             nj_clauses,
                             &binding,
                             accumulated_facts.clone(),
+                            Value::Null,
                             &fn_guard,
                         ) {
                             continue 'binding;
@@ -1411,6 +1414,7 @@ mod tests {
             &[expr_clause],
             &binding,
             facts,
+            Value::Null,
             &FunctionRegistry::with_builtins(),
         );
         assert!(
diff --git a/src/query/datalog/executor.rs b/src/query/datalog/executor.rs
index 16eaeb5b3..062c5abca 100644
--- a/src/query/datalog/executor.rs
+++ b/src/query/datalog/executor.rs
@@ -953,6 +953,7 @@ impl DatalogExecutor {
                         &join_vars,
                         &clauses,
                         derived_facts.clone(),
+                        valid_at_value.clone(),
                         &registry,
                     );
                 }
@@ -998,6 +999,7 @@ impl DatalogExecutor {
                     &join_vars,
                     &clauses,
                     derived_facts.clone(),
+                    valid_at_value.clone(),
                     &registry,
                 ),
                 _ => bindings,
@@ -1252,7 +1254,14 @@ fn apply_not_join_clause(
         return bindings
             .into_iter()
             .filter(|b| {
-                !evaluate_not_join(join_vars, nj_clauses, b, filtered_facts.clone(), registry)
+                !evaluate_not_join(
+                    join_vars,
+                    nj_clauses,
+                    b,
+                    filtered_facts.clone(),
+                    valid_at_value.clone(),
+                    registry,
+                )
             })
             .collect();
     }
@@ -1307,6 +1316,7 @@ fn apply_not_join_clause(
                 nj_clauses,
                 binding,
                 filtered_facts.clone(),
+                valid_at_value.clone(),
                 registry,
             )
         })
@@ -1448,11 +1458,21 @@ fn apply_not_join_clause_derived(
     join_vars: &[String],
     nj_clauses: &[WhereClause],
     derived_facts: Arc<[Fact]>,
+    valid_at_value: Value,
     registry: &FunctionRegistry,
 ) -> Vec<Binding> {
     bindings
         .into_iter()
-        .filter(|b| !evaluate_not_join(join_vars, nj_clauses, b, derived_facts.clone(), registry))
+        .filter(|b| {
+            !evaluate_not_join(
+                join_vars,
+                nj_clauses,
+                b,
+                derived_facts.clone(),
+                valid_at_value.clone(),
+                registry,
+            )
+        })
         .collect()
 }
 
@@ -2056,8 +2076,14 @@ pub(crate) fn evaluate_branch(
                     }
                 }
                 for (join_vars, nj_clauses) in &not_join_clauses {
-                    if evaluate_not_join(join_vars, nj_clauses, binding, storage.clone(), registry)
-                    {
+                    if evaluate_not_join(
+                        join_vars,
+                        nj_clauses,
+                        binding,
+                        storage.clone(),
+                        branch_valid_at_value.clone(),
+                        registry,
+                    ) {
                         return false;
                     }
                 }
diff --git a/tests/not_join_test.rs b/tests/not_join_test.rs
index 07f339430..62c0810d9 100644
--- a/tests/not_join_test.rs
+++ b/tests/not_join_test.rs
@@ -446,3 +446,111 @@ fn test_not_join_coexists_with_not_in_query() {
         "only charlie must pass: alice excluded by (not), bob excluded by (not-join)"
     );
 }
+
+/// #615: a `:db/valid-at` pattern in a `not-join` body binds the query's valid
+/// time on every path, not `nil` on the per-row one (body with an expression).
+#[test]
+fn test_not_join_valid_at_with_expr_binds_query_valid_time() {
+    let db = in_memory_db();
+    db.execute("(transact [[:a :n 1] [:b :n 2]])").unwrap();
+
+    let plain = db
+        .execute(
+            r#"(query [:find ?e :valid-at "2030-01-01"
+                       :where [?e :n _] (not-join [?e] [?e :db/valid-at ?t])])"#,
+        )
+        .unwrap();
+    assert_eq!(result_count(&plain), 0, "exclusion-set path excludes both");
+
+    let with_expr = db
+        .execute(
+            r#"(query [:find ?e :valid-at "2030-01-01"
+                       :where [?e :n _] (not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)])])"#,
+        )
+        .unwrap();
+    assert_eq!(result_count(&with_expr), 0, "per-row path excludes both");
+}
+
+/// #615: the same inside an `or` branch, where `not-join` always runs per row.
+#[test]
+fn test_not_join_valid_at_in_or_branch_binds_query_valid_time() {
+    let db = in_memory_db();
+    db.execute("(transact [[:a :n 1] [:b :n 2]])").unwrap();
+
+    let result = db
+        .execute(
+            r#"(query [:find ?e :valid-at "2030-01-01"
+                       :where [?e :n _]
+                              (or (and [?e :n 1] (not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)]))
+                                  (and [?e :n 2] (not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)])))])"#,
+        )
+        .unwrap();
+    assert_eq!(result_count(&result), 0, "or-branch not-join excludes both");
+}
+
+/// #615: the same in a query that invokes a rule (rules query path).
+#[test]
+fn test_not_join_valid_at_in_rule_query_binds_query_valid_time() {
+    let db = in_memory_db();
+    db.execute("(transact [[:a :n 1] [:b :n 2]])").unwrap();
+    db.execute("(rule [(numbered ?e) [?e :n _]])").unwrap();
+
+    let result = db
+        .execute(
+            r#"(query [:find ?e :valid-at "2030-01-01"
+                       :where (numbered ?e) (not-join [?e] [?e :db/valid-at ?t])])"#,
+        )
+        .unwrap();
+    assert_eq!(
+        result_count(&result),
+        0,
+        "rule-query not-join excludes both"
+    );
+
+    let with_expr = db
+        .execute(
+            r#"(query [:find ?e :valid-at "2030-01-01"
+                       :where (numbered ?e) (not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)])])"#,
+        )
+        .unwrap();
+    assert_eq!(
+        result_count(&with_expr),
+        0,
+        "rule-query not-join with expr excludes both"
+    );
+}
+
+/// #615: a `not-join` whose `?e` only an `or` binds runs after the `or`, on
+/// the rules query path's deferred pass, and binds the query's valid time too.
+#[test]
+fn test_not_join_valid_at_deferred_in_rule_query_binds_query_valid_time() {
+    let db = in_memory_db();
+    db.execute("(transact [[:a :n 1] [:b :n 2]])").unwrap();
+    db.execute("(rule [(numbered ?e) [?e :n _]])").unwrap();
+
+    let result = db
+        .execute(
+            r#"(query [:find ?x ?e :valid-at "2030-01-01"
+                       :where (numbered ?x)
+                              (or [?e :n 1] [?e :n 2])
+                              (not-join [?e] [?e :db/valid-at ?t] [(> ?t 0)])])"#,
+        )
+        .unwrap();
+    assert_eq!(
+        result_count(&result),
+        0,
+        "deferred not-join excludes every ?e"
+    );
+}
+
+/// A `not-join` body holding only an expression filters on the join variables.
+#[test]
+fn test_not_join_expression_only_body() {
+    let db = in_memory_db();
+    db.execute("(transact [[:a :n 1] [:b :n 2]])").unwrap();
+
+    let result = db
+        .execute("(query [:find ?e :where [?e :n ?v] (not-join [?v] [(> ?v 1)])])")
+        .unwrap();
+    assert_eq!(result_count(&result), 1, "only :a has ?v <= 1");
+}