diff --git a/changes.d/6404.fix.md b/changes.d/6404.fix.md
new file mode 100644
index 00000000000..6944919508e
--- /dev/null
+++ b/changes.d/6404.fix.md
@@ -0,0 +1 @@
+Use opts.against_source to pass rundir to plugins
diff --git a/cylc/flow/scripts/config.py b/cylc/flow/scripts/config.py
index aa7144a934d..830eae46e9a 100755
--- a/cylc/flow/scripts/config.py
+++ b/cylc/flow/scripts/config.py
@@ -52,6 +52,7 @@
 import asyncio
 
 import os.path
+from pathlib import Path
 from typing import List, Optional, TYPE_CHECKING
 
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
@@ -202,6 +203,11 @@ async def _main(
         print("\n".join(get_config_file_hierarchy(workflow_id)))
         return
 
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    if options.against_source:
+        options.against_source = Path(get_workflow_run_dir(workflow_id))
+
     config = WorkflowConfig(
         workflow_id,
         flow_file,
diff --git a/cylc/flow/scripts/graph.py b/cylc/flow/scripts/graph.py
index 56a60b6cced..6438e8de476 100644
--- a/cylc/flow/scripts/graph.py
+++ b/cylc/flow/scripts/graph.py
@@ -37,6 +37,7 @@
 
 import asyncio
 from difflib import unified_diff
+from pathlib import Path
 from shutil import which
 from subprocess import Popen, PIPE
 import sys
@@ -53,6 +54,7 @@
     CylcOptionParser as COP,
     icp_option,
 )
+from cylc.flow.pathutil import get_workflow_run_dir
 from cylc.flow.templatevars import get_template_vars
 from cylc.flow.terminal import cli_function
 
@@ -558,6 +560,11 @@ async def _main(
         constraint='workflows',
     )
 
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    if opts.against_source:
+        opts.against_source = Path(get_workflow_run_dir(workflow_id))
+
     if opts.diff:
         return await graph_diff(
             opts, workflow_id, opts.diff, start, stop, flow_file)
diff --git a/cylc/flow/scripts/list.py b/cylc/flow/scripts/list.py
index c0f1ed18ab7..c9702bea3dd 100755
--- a/cylc/flow/scripts/list.py
+++ b/cylc/flow/scripts/list.py
@@ -32,6 +32,7 @@
 
 import asyncio
 import os
+from pathlib import Path
 import sys
 from typing import TYPE_CHECKING
 
@@ -43,6 +44,7 @@
     CylcOptionParser as COP,
     icp_option,
 )
+from cylc.flow.workflow_files import get_workflow_run_dir
 from cylc.flow.templatevars import get_template_vars
 from cylc.flow.terminal import cli_function
 
@@ -151,6 +153,12 @@ async def _main(parser: COP, options: 'Values', workflow_id: str) -> None:
             [options.all_tasks, options.all_namespaces, options.mro]):
         print("WARNING: -t chosen, ignoring non-tree options.",
               file=sys.stderr)
+
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    if options.against_source:
+        options.against_source = Path(get_workflow_run_dir(workflow_id))
+
     config = WorkflowConfig(
         workflow_id,
         flow_file,
diff --git a/cylc/flow/scripts/validate.py b/cylc/flow/scripts/validate.py
index ee359b51847..76ba2ce28ff 100755
--- a/cylc/flow/scripts/validate.py
+++ b/cylc/flow/scripts/validate.py
@@ -28,6 +28,7 @@
 import asyncio
 from ansimarkup import parse as cparse
 from copy import deepcopy
+from pathlib import Path
 import sys
 from typing import TYPE_CHECKING
 
@@ -55,6 +56,7 @@
 from cylc.flow.templatevars import get_template_vars
 from cylc.flow.terminal import cli_function
 from cylc.flow.scheduler_cli import RUN_MODE
+from cylc.flow.workflow_files import get_workflow_run_dir
 from cylc.flow.workflow_status import RunMode
 
 if TYPE_CHECKING:
@@ -153,6 +155,12 @@ async def run(
         src=True,
         constraint='workflows',
     )
+
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    if getattr(options, 'against_source', False):
+        options.against_source = Path(get_workflow_run_dir(workflow_id))
+
     cfg = WorkflowConfig(
         workflow_id,
         flow_file,
diff --git a/cylc/flow/scripts/validate_reinstall.py b/cylc/flow/scripts/validate_reinstall.py
index 1385ad20bc1..4e78d673d7e 100644
--- a/cylc/flow/scripts/validate_reinstall.py
+++ b/cylc/flow/scripts/validate_reinstall.py
@@ -40,6 +40,7 @@
 """
 
 import asyncio
+from pathlib import Path
 import sys
 from typing import TYPE_CHECKING, Union
 
@@ -75,7 +76,10 @@
     run as cylc_reload
 )
 from cylc.flow.terminal import cli_function
-from cylc.flow.workflow_files import detect_old_contact_file
+from cylc.flow.workflow_files import (
+    detect_old_contact_file,
+    get_workflow_run_dir,
+)
 
 CYLC_ROSE_OPTIONS = COP.get_cylc_rose_options()
 VR_OPTIONS = combine_options(
@@ -186,8 +190,9 @@ async def vr_cli(
     ):
         return False
 
-    # Force on the against_source option:
-    options.against_source = True
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    options.against_source = Path(get_workflow_run_dir(workflow_id))
 
     # Run cylc validate
     log_subcommand('validate --against-source', workflow_id)
diff --git a/cylc/flow/scripts/view.py b/cylc/flow/scripts/view.py
index 3fe5c59e49d..6eaa2bd6bb1 100644
--- a/cylc/flow/scripts/view.py
+++ b/cylc/flow/scripts/view.py
@@ -34,6 +34,7 @@
 """
 
 import asyncio
+from pathlib import Path
 from typing import TYPE_CHECKING
 
 from cylc.flow.id_cli import parse_id_async
@@ -42,6 +43,7 @@
     WORKFLOW_ID_OR_PATH_ARG_DOC,
     CylcOptionParser as COP,
 )
+from cylc.flow.pathutil import get_workflow_run_dir
 from cylc.flow.parsec.fileparse import read_and_proc
 from cylc.flow.templatevars import get_template_vars
 from cylc.flow.terminal import cli_function
@@ -122,6 +124,12 @@ async def _main(options: 'Values', workflow_id: str) -> None:
         src=True,
         constraint='workflows',
     )
+
+    # Save the location of the existing workflow run dir in the
+    # against source option:
+    if options.against_source:
+        options.against_source = Path(get_workflow_run_dir(workflow_id))
+
     # read in the flow.cylc file
     for line in read_and_proc(
         flow_file,