diff --git a/core/test.py b/core/test.py
index f56582e9..3785a511 100644
--- a/core/test.py
+++ b/core/test.py
@@ -130,6 +130,13 @@ def _exec_run(self, tree, thing, result_dir):
if hasattr(thing, 'first_in_series'):
env["FIRST_IN_SERIES"] = str(int(thing.first_in_series))
+ if hasattr(thing, 'pw_series'):
+ pw_series = thing.pw_series
+ if pw_series['cover_letter']:
+ env["MSGID"] = str(pw_series['cover_letter']['msgid'])
+ elif pw_series['patches']:
+ env["MSGID"] = str(pw_series['patches'][0]['msgid'])
+
out, err = CMD.cmd_run(self.info["run"], include_stderr=True, cwd=tree.path,
pass_fds=[wfd], add_env=env)
except core.cmd.CmdError as e:
diff --git a/docker/build/Dockerfile b/docker/build/Dockerfile
index 20a0a58b..684182e2 100644
--- a/docker/build/Dockerfile
+++ b/docker/build/Dockerfile
@@ -7,7 +7,7 @@ LABEL name=nipa-build
RUN sudo dnf install -y \
clang llvm lld \
- ruff pylint yamllint jsonschema shellcheck \
+ b4 ruff pylint yamllint jsonschema shellcheck \
dwarves libasan libasan-static glibc-devel.i686 \
rustc \
perl-Git lei \
diff --git a/tests/series/diff/diff.sh b/tests/series/diff/diff.sh
new file mode 100755
index 00000000..33901f04
--- /dev/null
+++ b/tests/series/diff/diff.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2026 Matthieu Baerts
+
+if [ -z "${MSGID}" ]; then
+ echo "MSGID not set" >&"${DESC_FD}"
+ exit 0
+fi
+
+OUT="${RESULTS_DIR}/b4-diff.ansi"
+
+# ignore errors, we just want to see the diff if available
+b4 diff --color --output-diff "${OUT}" "${MSGID}" || true
+
+if [ -s "${OUT}" ]; then
+ echo "Diff with the previous version in $(basename "${OUT}")" >&"${DESC_FD}"
+else
+ echo "No diff available" >&"${DESC_FD}"
+fi
diff --git a/tests/series/diff/info.json b/tests/series/diff/info.json
new file mode 100644
index 00000000..20870b77
--- /dev/null
+++ b/tests/series/diff/info.json
@@ -0,0 +1,3 @@
+{
+ "run": ["diff.sh"]
+}
diff --git a/ui/ansiview.html b/ui/ansiview.html
new file mode 100644
index 00000000..0a72f27d
--- /dev/null
+++ b/ui/ansiview.html
@@ -0,0 +1,438 @@
+
+
+
+
+
+NIPA log viewer
+
+
+
+
+
+
+
+
+