diff --git a/docs/source/conf.py b/docs/source/conf.py
index 81d249c..e18817c 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -2,6 +2,8 @@
 import sys
 import os
 
+sys.path.append(os.path.abspath(f"{__file__}/../../../sbysrc"))
+
 project = 'YosysHQ SBY'
 author = 'YosysHQ GmbH'
 copyright = '2023 YosysHQ GmbH'
@@ -43,5 +45,3 @@ html_theme_options = {
 
 extensions = ['sphinx.ext.autosectionlabel']
 extensions += ['sphinxarg.ext']
-
-sys.path.append(os.path.abspath(f"{__file__}/../../../sbysrc"))
diff --git a/sbysrc/sby_autotune.py b/sbysrc/sby_autotune.py
index 771a9a0..1d6f102 100644
--- a/sbysrc/sby_autotune.py
+++ b/sbysrc/sby_autotune.py
@@ -402,7 +402,7 @@ class SbyAutotune:
 
         self.build_candidates()
         if not self.active_candidates:
-            self.error("no supported engines found for the current configuration and design")
+            self.task.error("no supported engines found for the current configuration and design")
         self.log(f"testing {len(self.active_candidates)} engine configurations...")
 
         self.start_engines()
diff --git a/sbysrc/sby_core.py b/sbysrc/sby_core.py
index 1213fb7..48a4c2a 100644
--- a/sbysrc/sby_core.py
+++ b/sbysrc/sby_core.py
@@ -1154,7 +1154,7 @@ class SbyTask(SbyConfig):
                 self,
                 model_name,
                 self.model("aig"),
-                f"""cd {self.workdir}/model; {self.exe_paths["abc"]} -c 'read_aiger design_aiger.aig; fold; strash; write_aiger design_aiger_fold.aig'""",
+                f"""cd {self.workdir}/model; {self.exe_paths["abc"]} -c 'read_aiger design_aiger.aig; fold{" -s" if self.opt_aigfolds else ""}; strash; write_aiger design_aiger_fold.aig'""",
                 logfile=open(f"{self.workdir}/model/design_aiger_fold.log", "w")
             )
             proc.checkretcode = True
@@ -1236,6 +1236,7 @@ class SbyTask(SbyConfig):
         self.handle_bool_option("fst", False)
 
         self.handle_bool_option("witrename", True)
+        self.handle_bool_option("aigfolds", False)
         self.handle_bool_option("aigvmap", False)
         self.handle_bool_option("aigsyms", False)
 
diff --git a/sbysrc/sby_engine_abc.py b/sbysrc/sby_engine_abc.py
index 1cb84b5..639a7ff 100644
--- a/sbysrc/sby_engine_abc.py
+++ b/sbysrc/sby_engine_abc.py
@@ -42,7 +42,7 @@ def run(mode, task, engine_idx, engine):
     elif abc_command[0] == "pdr":
         if mode != "prove":
             task.error("ABC command 'pdr' is only valid in prove mode.")
-        abc_command[0] += f" -v"
+        abc_command[0] += f" -v -I engine_{engine_idx}/invariants.pla"
 
     else:
         task.error(f"Invalid ABC command {abc_command[0]}.")
@@ -66,7 +66,9 @@ def run(mode, task, engine_idx, engine):
         task,
         f"engine_{engine_idx}",
         task.model("aig"),
-        f"""cd {task.workdir}; {task.exe_paths["abc"]} -c 'read_aiger model/design_aiger.aig; fold; strash; {" ".join(abc_command)}; write_cex -a engine_{engine_idx}/trace.aiw'""",
+        f"""cd {task.workdir}; {task.exe_paths["abc"]} -c 'read_aiger model/design_aiger.aig; fold{
+                " -s" if task.opt_aigfolds or (abc_command[0].startswith("pdr ") and "-d" in abc_command[1:]) else ""
+                }; strash; {" ".join(abc_command)}; write_cex -a engine_{engine_idx}/trace.aiw'""",
         logfile=open(f"{task.workdir}/engine_{engine_idx}/logfile.txt", "w")
     )
     proc.checkretcode = True
diff --git a/sbysrc/sby_engine_smtbmc.py b/sbysrc/sby_engine_smtbmc.py
index c5f348e..7558c09 100644
--- a/sbysrc/sby_engine_smtbmc.py
+++ b/sbysrc/sby_engine_smtbmc.py
@@ -69,8 +69,6 @@ def run(mode, task, engine_idx, engine):
                 task.error("smtbmc options --basecase and --induction are exclusive.")
             induction_only = True
         elif o == "--keep-going":
-            if mode not in ("bmc", "prove", "prove_basecase", "prove_induction"):
-                task.error("smtbmc option --keep-going is only supported in bmc and prove mode.")
             keep_going = True
         elif o == "--seed":
             random_seed = a
@@ -134,7 +132,8 @@ def run(mode, task, engine_idx, engine):
 
     if keep_going and mode != "prove_induction":
         smtbmc_opts.append("--keep-going")
-        trace_prefix += "%"
+        if mode != "cover":
+            trace_prefix += "%"
 
     if dumpsmt2:
         smtbmc_opts += ["--dump-smt2", trace_prefix.replace("%", "") + ".smt2"]
diff --git a/sbysrc/sby_jobserver.py b/sbysrc/sby_jobserver.py
index a350133..57d751d 100644
--- a/sbysrc/sby_jobserver.py
+++ b/sbysrc/sby_jobserver.py
@@ -80,7 +80,16 @@ def process_jobserver_environment():
 
 def jobserver_helper(jobserver_read_fd, jobserver_write_fd, request_fd, response_fd):
     """Helper process to handle blocking jobserver pipes."""
+    def handle_sigusr1(*args):
+        # Since Python doesn't allow user code to handle EINTR anymore, we replace the
+        # jobserver fd with an fd at EOF to interrupt a blocking read in a way that
+        # cannot lose any read data
+        r, w = os.pipe()
+        os.close(w)
+        os.dup2(r, jobserver_read_fd)
+        os.close(r)
     signal.signal(signal.SIGINT, signal.SIG_IGN)
+    signal.signal(signal.SIGUSR1, handle_sigusr1)
     pending = 0
     while True:
         try:
@@ -110,6 +119,8 @@ def jobserver_helper(jobserver_read_fd, jobserver_write_fd, request_fd, response
             except BlockingIOError:
                 select.select([jobserver_read_fd], [], [])
                 continue
+            if not token:
+                break
 
             pending -= 1
 
@@ -240,6 +251,10 @@ class SbyJobClient:
             # Closing the request pipe singals the helper that we want to exit
             os.close(self.request_write_fd)
 
+            # Additionally we send a signal to interrupt a blocking read within the
+            # helper
+            self.helper_process.send_signal(signal.SIGUSR1)
+
             # The helper might have been in the process of sending us some tokens, which
             # we still need to return
             while True: