diff --git a/analysis/tests/test_foundry_run_showmap_args.py b/analysis/tests/test_foundry_run_showmap_args.py
index 43e02f1..f0e8f89 100644
--- a/analysis/tests/test_foundry_run_showmap_args.py
+++ b/analysis/tests/test_foundry_run_showmap_args.py
@@ -152,7 +152,7 @@ def test_showmap_replay_uses_explicit_corpus_override_only_when_set(self):
             corpus_idx = replay_args.index("--showmap-corpus-dir")
             self.assertEqual(replay_args[corpus_idx + 1], str(corpus_dir))
 
-    def test_showmap_replay_uses_bounded_default_timeout(self):
+    def test_showmap_replay_scales_timeout_with_fuzz_budget(self):
         def run_case(timeout: str, override: str | None = None) -> list[list[str]]:
             with tempfile.TemporaryDirectory() as tmp:
                 tmp_dir = Path(tmp)
@@ -179,14 +179,16 @@ def run_case(timeout: str, override: str | None = None) -> list[list[str]]:
                 lines = (log_dir / "commands.tsv").read_text(encoding="utf-8").splitlines()
                 return [line.split("\t") for line in lines]
 
+        # Replay budget scales with the fuzz budget, not a fixed cap.
         long_campaign = run_case("86400")
         self.assertEqual(long_campaign[0][1], "86400")
-        self.assertEqual(long_campaign[1][1], "1800")
+        self.assertEqual(long_campaign[1][1], "86400")
 
         short_campaign = run_case("60")
         self.assertEqual(short_campaign[0][1], "60")
         self.assertEqual(short_campaign[1][1], "60")
 
+        # Explicit override still wins.
         explicit_override = run_case("86400", "42")
         self.assertEqual(explicit_override[0][1], "86400")
         self.assertEqual(explicit_override[1][1], "42")
diff --git a/fuzzers/foundry/run.sh b/fuzzers/foundry/run.sh
index 09ce9dc..c05efa7 100644
--- a/fuzzers/foundry/run.sh
+++ b/fuzzers/foundry/run.sh
@@ -137,9 +137,14 @@ if [[ "${showmap_enabled}" == "1" || "${showmap_enabled_lc}" == "true" || "${sho
   original_timeout="${SCFUZZBENCH_TIMEOUT_SECONDS:-}"
   showmap_timeout="${SCFUZZBENCH_FOUNDRY_SHOWMAP_TIMEOUT_SECONDS:-}"
   if [[ -z "${showmap_timeout}" ]]; then
-    showmap_timeout=1800
-    if [[ "${original_timeout}" =~ ^[0-9]+$ ]] && [[ "${original_timeout}" -gt 0 ]] && [[ "${original_timeout}" -lt "${showmap_timeout}" ]]; then
+    # Replay cost grows with corpus size, which grows with the fuzz budget, so
+    # scale the budget rather than capping it: a fixed cap silently truncated
+    # the replay on slow targets and dropped their coverage. Replay is normally
+    # far faster than fuzzing, so the ceiling is only reached by slow targets.
+    if [[ "${original_timeout}" =~ ^[0-9]+$ ]] && [[ "${original_timeout}" -gt 0 ]]; then
       showmap_timeout="${original_timeout}"
+    else
+      showmap_timeout=1800
     fi
   fi
   SCFUZZBENCH_TIMEOUT_SECONDS="${showmap_timeout}"