diff --git a/src/Storages/MergeTree/KeyCondition.cpp b/src/Storages/MergeTree/KeyCondition.cpp
index d58dd37232b5..6e1b8ed25ed1 100644
--- a/src/Storages/MergeTree/KeyCondition.cpp
+++ b/src/Storages/MergeTree/KeyCondition.cpp
@@ -5180,8 +5180,11 @@ bool KeyCondition::matchesExactContinuousRange() const
                 Constraint & constraint = column_constraints.at(mapping.key_index);
                 /// For Constraint::POINT, we need to check if the function chain is strict.
                 /// For example, `toDate(event_time) in ('2025-06-03')` means a range of `event_time`: ['2025-06-03 00:00:00','2025-06-04 00:00:00')
-                /// So, POINT needs to be converted to a RANGE
-                if (is_chain_strict)
+                /// So, POINT needs to be converted to a RANGE.
+                /// Only an empty chain yields an exact point. A non-empty chain (e.g. a widening CAST for
+                /// a wider-typed constant) is applied to granule bounds with forced-closed bounds, so it
+                /// cannot promise exact continuity across a boundary granule; treat it as a RANGE (#90461).
+                if (is_chain_strict && mapping.functions.empty())
                     constraint = Constraint::POINT;
                 else
                 {
@@ -5205,8 +5208,11 @@ bool KeyCondition::matchesExactContinuousRange() const
             {
                 /// For Constraint::POINT, we need to check if the function chain is strict.
                 /// For example, `toDate(event_time) = '2025-06-03'` means a range of `event_time`: ['2025-06-03 00:00:00','2025-06-04 00:00:00')
-                /// So, POINT needs to be converted to a RANGE
-                if (is_chain_strict)
+                /// So, POINT needs to be converted to a RANGE.
+                /// Only an empty chain yields an exact point. A non-empty chain (e.g. a widening CAST for
+                /// a wider-typed constant) is applied to granule bounds with forced-closed bounds, so it
+                /// cannot promise exact continuity across a boundary granule; treat it as a RANGE (#90461).
+                if (is_chain_strict && element.monotonic_functions_chain.empty())
                     constraint = Constraint::POINT;
             }
 
diff --git a/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.reference b/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.reference
new file mode 100644
index 000000000000..ad603edbaace
--- /dev/null
+++ b/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.reference
@@ -0,0 +1,31 @@
+1
+1
+13
+13
+13
+13
+13
+13
+1
+13
+13
+13
+1
+1
+3
+3
+3
+3
+3
+1
+1
+3
+3
+3
+1
+1
+10
+10
+10
+10
+10
diff --git a/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.sh b/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.sh
new file mode 100755
index 000000000000..c737db974b41
--- /dev/null
+++ b/tests/queries/0_stateless/04493_key_condition_wide_type_exact_range.sh
@@ -0,0 +1,141 @@
+#!/usr/bin/env bash
+# Regression for the debug-only "Inconsistent KeyCondition behavior" logical error (#90461 canary).
+#
+# Comparing the first key column against a wider-typed constant (e.g. UInt64 key vs toUInt256(...))
+# inserts a widening CAST into the monotonic function chain. matchesExactContinuousRange used to
+# classify such a column as an exact POINT because the CAST is strictly monotonic, but checkInRange
+# applies the chain to granule bounds with forced-closed bounds, so a granule straddling a key
+# boundary is honestly reported as can_be_false. The exact continuous-range (implicit count
+# projection) path then contradicted that and aborted in debug builds.
+#
+# The trigger needs the parts read fresh from disk in a separate process, so use clickhouse-local
+# with a persisted table: build the data in one invocation, then run the count queries in a second.
+# In release builds the broken exact range is dropped and read normally, so the count stays correct;
+# here we check the queries do not abort and return the same value as the bare (native-typed) comparison.
+
+CUR_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CUR_DIR"/../shell_config.sh
+
+DB_DIR="${CLICKHOUSE_TMP}/04493_${CLICKHOUSE_DATABASE}"
+rm -rf "${DB_DIR}"
+mkdir -p "${DB_DIR}"
+
+# Build a multi-column-key table with a tiny granularity and several distinct first-key values, so
+# granules straddle the team_id boundary. Persist it to disk.
+${CLICKHOUSE_LOCAL} --path="${DB_DIR}" --multiquery --query "
+CREATE TABLE t (team_id UInt64, k UInt8, s String)
+ENGINE = MergeTree ORDER BY (team_id, k, s) SETTINGS index_granularity = 4;
+SYSTEM STOP MERGES t;
+INSERT INTO t SELECT 1, number % 5, toString(number) FROM numbers(50);
+INSERT INTO t SELECT 2, number % 5, toString(number) FROM numbers(50);
+INSERT INTO t SELECT number % 3, number % 5, toString(number) FROM numbers(50);
+"
+
+# Query the persisted table in a separate process. Each of these used to abort with
+# "Inconsistent KeyCondition behavior" in debug builds; all must equal the native-typed count (13).
+# Pin the projection settings so the exact-count path is exercised regardless of their defaults.
+${CLICKHOUSE_LOCAL} --path="${DB_DIR}" --multiquery --query "
+SET optimize_use_projections = 1;
+SET optimize_use_implicit_projections = 1;
+-- Assert the wide-typed comparison is routed through the exact-count projection (the abort path); count alone passes even if it is silently declined.
+SELECT count() > 0 FROM (EXPLAIN SELECT count() FROM t WHERE team_id = toUInt256(1) AND k = 0) WHERE explain ILIKE '%_exact_count_projection%';
+-- Assert the wide-typed comparison forces generic-exclusion index search: the fix demotes the leading key from POINT to RANGE. This distinguishes fixed from reverted code even in release, where the debug abort is compiled out.
+SELECT count() > 0 FROM (EXPLAIN indexes = 1 SELECT count() FROM t WHERE team_id = toUInt256(1) AND k = 0) WHERE explain ILIKE '%generic exclusion search%';
+SELECT count() FROM t WHERE team_id = 1 AND k = 0;
+SELECT count() FROM t WHERE team_id = toUInt256(1) AND k = 0;
+SELECT count() FROM t WHERE team_id = toInt256(1) AND k = 0;
+SELECT count() FROM t WHERE team_id = toUInt128(1) AND k = 0;
+SELECT count() FROM t WHERE team_id = toInt128(1) AND k = 0;
+SELECT count() FROM t WHERE team_id IN (toUInt256(1)) AND k = 0;
+-- A wider-typed cast applied to the key inside IN (not a bare key) populates the set-index function chain,
+-- so this exercises the changed non-empty mapping.functions branch; it must also route through generic exclusion.
+SELECT count() > 0 FROM (EXPLAIN indexes = 1 SELECT count() FROM t WHERE toUInt256(team_id) IN (toUInt256(1)) AND k = 0) WHERE explain ILIKE '%generic exclusion search%';
+SELECT count() FROM t WHERE toUInt256(team_id) IN (toUInt256(1)) AND k = 0;
+SELECT count() FROM t WHERE team_id = toUInt256(1) AND k = toUInt256(0);
+SELECT count() FROM t WHERE team_id = toUInt256(1) AND k = 0 SETTINGS force_primary_key = 1;
+"
+
+rm -rf "${DB_DIR}"
+
+# Issue #111421 (qoega): composite (x, y, z) key at index_granularity = 1, a count() with the wider-typed
+# equality on the leading key AND range conditions on the rest, over a multi-x dataset. This is the
+# aggregate-projection exact-count path with the mark layout fine enough to disagree with the analyzer's
+# continuous-range claim; it aborted in debug and read normally (correct count) in release. Correct count
+# is 3: rows (3,55,1235),(3,55,2791),(3,55,5786), all with z <= 5786.
+DB_DIR2="${CLICKHOUSE_TMP}/04493b_${CLICKHOUSE_DATABASE}"
+rm -rf "${DB_DIR2}"
+mkdir -p "${DB_DIR2}"
+
+${CLICKHOUSE_LOCAL} --path="${DB_DIR2}" --multiquery --query "
+CREATE TABLE pk (x UInt64, y UInt64, z UInt64)
+ENGINE = MergeTree ORDER BY (x, y, z) SETTINGS index_granularity = 1;
+INSERT INTO pk VALUES
+  (1, 11, 1235), (1, 11, 4395), (1, 22, 3545), (1, 22, 6984), (1, 33, 4596),
+  (2, 11, 3572), (2, 11, 4563), (2, 11, 4578), (2, 22, 2791), (2, 22, 2791),
+  (2, 22, 5786), (2, 22, 5786), (3, 33, 1235), (3, 33, 2791), (3, 33, 2791),
+  (3, 44, 4578), (3, 44, 4935), (3, 55, 1235), (3, 55, 2791), (3, 55, 5786);
+"
+
+# Query in a separate process. Used to abort in debug; must return 3 (matching the native-typed comparison).
+# Pin the projection settings so the exact-count path is exercised regardless of their defaults.
+${CLICKHOUSE_LOCAL} --path="${DB_DIR2}" --multiquery --query "
+SET optimize_use_projections = 1;
+SET optimize_use_implicit_projections = 1;
+-- Assert the wide-typed comparison is routed through the exact-count projection (the abort path); count alone passes even if it is silently declined.
+SELECT count() > 0 FROM (EXPLAIN SELECT count() FROM pk WHERE (x = toUInt256(3)) AND (y = 55) AND (5786 >= z)) WHERE explain ILIKE '%_exact_count_projection%';
+-- Assert generic-exclusion index search (leading key demoted POINT -> RANGE by the fix); distinguishes fixed from reverted code in release too.
+SELECT count() > 0 FROM (EXPLAIN indexes = 1 SELECT count() FROM pk WHERE (x = toUInt256(3)) AND (y = 55) AND (5786 >= z)) WHERE explain ILIKE '%generic exclusion search%';
+SELECT count() FROM pk WHERE (x = 3) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = toUInt256(3)) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = toInt256(3)) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = toUInt128(3)) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = toUInt256(3)) AND (y = 55) AND (5786 >= z) SETTINGS optimize_use_implicit_projections = 0;
+"
+
+# A native exact-point atom and a widened-cast atom on the same key column (x = 3 AND x = toUInt256(3)).
+# enable_analyzer = 0 keeps both atoms in the key condition (the analyzer folds them into one); the
+# column is then pinned POINT by the native equality while the redundant cast atom stays in the rpn. This
+# must still yield an exact, consistent range: expect the native count (3), the exact-count path live, no abort.
+${CLICKHOUSE_LOCAL} --path="${DB_DIR2}" --multiquery --query "
+SET enable_analyzer = 0;
+SET optimize_use_projections = 1;
+SET optimize_use_implicit_projections = 1;
+SELECT count() > 0 FROM (EXPLAIN SELECT count() FROM pk WHERE (x = 3) AND (x = toUInt256(3)) AND (y = 55) AND (5786 >= z)) WHERE explain ILIKE '%_exact_count_projection%';
+-- The native x = 3 atom must keep the leading key at POINT (binary search); the redundant widened-cast
+-- atom must not overwrite it into a RANGE. Generic exclusion also yields exact ranges, so assert the
+-- search algorithm directly, otherwise the count/exact-count assertions pass even if the point were lost.
+SELECT count() > 0 FROM (EXPLAIN indexes = 1 SELECT count() FROM pk WHERE (x = 3) AND (x = toUInt256(3)) AND (y = 55) AND (5786 >= z)) WHERE explain ILIKE '%binary search%';
+SELECT count() FROM pk WHERE (x = 3) AND (x = toUInt256(3)) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = 3) AND (x = toInt256(3)) AND (y = 55) AND (5786 >= z);
+SELECT count() FROM pk WHERE (x = 3) AND (x = toUInt128(3)) AND (y = 55) AND (5786 >= z);
+"
+
+rm -rf "${DB_DIR2}"
+
+# Same wider-typed cast on the leading key, now with a DESCending key column (ORDER BY (g, r DESC)):
+# the fix is order-independent, so this must also return the native count (10), not abort.
+DB_DIR3="${CLICKHOUSE_TMP}/04493c_${CLICKHOUSE_DATABASE}"
+rm -rf "${DB_DIR3}"
+mkdir -p "${DB_DIR3}"
+
+${CLICKHOUSE_LOCAL} --path="${DB_DIR3}" --multiquery --query "
+CREATE TABLE t_rev (g UInt32, r UInt32) ENGINE = MergeTree ORDER BY (g, r DESC) SETTINGS index_granularity = 4;
+INSERT INTO t_rev SELECT number % 10, 1000 - number FROM numbers(1000);
+"
+
+${CLICKHOUSE_LOCAL} --path="${DB_DIR3}" --multiquery --query "
+SET optimize_use_projections = 1;
+SET optimize_use_implicit_projections = 1;
+-- Exact-count projection path live (the abort path) and generic-exclusion index search (leading key
+-- demoted POINT -> RANGE by the fix); the second assertion distinguishes fixed from reverted code in release too.
+SELECT count() > 0 FROM (EXPLAIN SELECT count() FROM t_rev WHERE (g = toUInt256(5)) AND (toInt64(r) >= 900)) WHERE explain ILIKE '%_exact_count_projection%';
+SELECT count() > 0 FROM (EXPLAIN indexes = 1 SELECT count() FROM t_rev WHERE (g = toUInt256(5)) AND (toInt64(r) >= 900)) WHERE explain ILIKE '%generic exclusion search%';
+SELECT count() FROM t_rev WHERE (g = 5) AND (toInt64(r) >= 900);
+SELECT count() FROM t_rev WHERE (g = toUInt256(5)) AND (toInt64(r) >= 900);
+SELECT count() FROM t_rev WHERE (g = toInt256(5)) AND (toInt64(r) >= 900);
+SELECT count() FROM t_rev WHERE (g = toUInt128(5)) AND (toInt64(r) >= 900);
+SELECT count() FROM t_rev WHERE (g = toUInt256(5)) AND (toInt64(r) >= 900) SETTINGS optimize_use_implicit_projections = 0;
+"
+
+rm -rf "${DB_DIR3}"