diff --git a/README.md b/README.md
index 848dd9fd3..60f36fef9 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@ built as a plugin on top of [DMTCP](https://github.com/dmtcp/dmtcp).
 
 For details of installing and using MANA, please see:
 - [MANA Manual](https://github.com/mpickpt/mana/wiki)
+  * [Distributed MPICH/Hydra checkpoint and restart](doc/distributed-mpich-hydra.md)
 
 Older documentation:
 - [MANA documentation (https://mana-doc.readthedocs.io/en/latest/) ](https://mana-doc.readthedocs.io/en/latest/)
diff --git a/doc/distributed-mpich-hydra.md b/doc/distributed-mpich-hydra.md
new file mode 100644
index 000000000..787f9b6ba
--- /dev/null
+++ b/doc/distributed-mpich-hydra.md
@@ -0,0 +1,569 @@
+# Distributed MPICH/Hydra checkpoint and restart
+
+This guide describes an opt-in, multi-node MANA workflow using MPICH's
+Hydra process manager and SSH launch.
+
+Paths and node names below are examples. Unless a directory is stored on
+shared storage, every participating node must use the same absolute paths for:
+
+- MANA;
+- MPICH;
+- the MPI application;
+- the working directory;
+- temporary files;
+- checkpoint files;
+- the isolated test home containing `.mana.rc`.
+
+## 1. Prerequisites
+
+Each node needs:
+
+- the same MANA revision and build;
+- the same MPICH installation;
+- passwordless SSH from the launch node;
+- a working C and C++ compiler toolchain;
+- compatible runtime libraries;
+- write access to the selected working, checkpoint, temporary, and log
+  directories;
+- loader debug symbols when required by the lower half.
+
+The launch node also needs a Hydra hostfile containing one host or host
+specification per line.
+
+Do not store private SSH keys, scheduler credentials, checkpoint images,
+status files, or cluster-specific hostfiles in the MANA repository.
+
+## 2. Build MANA against the intended MPICH
+
+Do not rely on whichever `mpicc` happens to be first in the system path.
+An accidental Open MPI build can instantiate incompatible `ompi_*` handle
+types.
+
+```bash
+export MPICH_HOME=/opt/mpich-mana
+
+export PATH="$MPICH_HOME/bin:$PATH"
+export LD_LIBRARY_PATH="$MPICH_HOME/lib:${LD_LIBRARY_PATH:-}"
+
+CFLAGS="-O2 -fno-stack-protector" \
+CXXFLAGS="-O2 -fno-stack-protector" \
+MPI_BIN="$MPICH_HOME/bin" \
+MPI_INCLUDE="$MPICH_HOME/include" \
+MPI_LIB="$MPICH_HOME/lib" \
+MPICC="$MPICH_HOME/bin/mpicc" \
+MPICXX="$MPICH_HOME/bin/mpicxx" \
+MPIFORTRAN="$MPICH_HOME/bin/mpifort" \
+MPIRUN="$MPICH_HOME/bin/mpirun" \
+MPI_LD_FLAG="-lmpich" \
+MPI_CFLAGS="" \
+MPI_CXXFLAGS="" \
+MPI_LDFLAGS="" \
+MAKE=/usr/bin/make \
+./configure
+
+/usr/bin/make -j"$(nproc)" mana
+```
+
+Confirm that the generated configuration refers to the selected MPICH:
+
+```bash
+grep -E \
+  '^(MPI_BIN|MPI_INCLUDE|MPI_LIB|MPICC|MPICXX|MPIFORTRAN|MPIRUN|MPI_LD_FLAG)' \
+  mpi-proxy-split/Makefile_config
+```
+
+Check the lower-half linkage:
+
+```bash
+ldd bin/lower-half |
+grep -E 'libmpi|not found'
+```
+
+The MPI library should resolve under `$MPICH_HOME/lib`, and no library should
+be reported as `not found`.
+
+The file below is a generated executable and must not be committed:
+
+```text
+mpi-proxy-split/lower-half/lower-half
+```
+
+## 3. Define the distributed test environment
+
+For example:
+
+```bash
+export MANA_HOME=/opt/mana
+export MPICH_HOME=/opt/mpich-mana
+
+export HOSTFILE=/path/to/hosts.txt
+export REMOTE_USER="$USER"
+
+export WORKDIR=/tmp/mana-distributed-test
+export TEST_HOME="$WORKDIR/home"
+export CKPTDIR="$WORKDIR/checkpoints"
+export TMPDIR="$WORKDIR/tmp"
+export LOGDIR="$WORKDIR/logs"
+
+export STATUS_FILE="$TEST_HOME/.mana.rc"
+```
+
+`TEST_HOME` is intentionally separate from the user's normal home directory.
+MANA launch and restart commands read coordinator information from:
+
+```text
+$HOME/.mana.rc
+```
+
+The MPI ranks will therefore receive:
+
+```bash
+-genv HOME "$TEST_HOME"
+```
+
+The same absolute `TEST_HOME` path must exist on every node.
+
+## 4. Validate SSH, paths, and runtime libraries
+
+For every unique host:
+
+```bash
+while IFS= read -r node || [[ -n "$node" ]]; do
+    node="${node%%[[:space:]]*}"
+
+    [[ -z "$node" || "$node" == \#* ]] && continue
+
+    ssh -n "$REMOTE_USER@$node" "
+      set -e
+
+      test -x '$MANA_HOME/bin/mana_launch'
+      test -x '$MANA_HOME/bin/mana_restart'
+      test -x '$MANA_HOME/bin/lower-half'
+      test -x '$MPICH_HOME/bin/hydra_pmi_proxy'
+
+      mkdir -p \
+        '$WORKDIR' \
+        '$TEST_HOME' \
+        '$CKPTDIR' \
+        '$TMPDIR' \
+        '$LOGDIR'
+    "
+done < "$HOSTFILE"
+```
+
+Use `ssh -n` in loops that read standard input. Without `-n`, SSH can consume
+the remaining hostfile lines.
+
+Check unresolved libraries on each node:
+
+```bash
+while IFS= read -r node || [[ -n "$node" ]]; do
+    node="${node%%[[:space:]]*}"
+
+    [[ -z "$node" || "$node" == \#* ]] && continue
+
+    echo "===== $node ====="
+
+    ssh -n "$REMOTE_USER@$node" "
+      export LD_LIBRARY_PATH='$MANA_HOME/lib:$MANA_HOME/lib/dmtcp:$MPICH_HOME/lib'
+
+      unresolved=\$(
+        ldd '$MANA_HOME/bin/lower-half' |
+        grep 'not found' || true
+      )
+
+      if [[ -n \"\$unresolved\" ]]; then
+        printf '%s\n' \"\$unresolved\"
+        exit 1
+      fi
+
+      ldd '$MANA_HOME/bin/lower-half' |
+      grep -E 'libmpi|libatomic' || true
+    "
+done < "$HOSTFILE"
+```
+
+A copied binary can fail remotely when a runtime package exists only on the
+build node. Resolve all missing libraries before testing MANA.
+
+## 5. Run a native MPICH/Hydra smoke test
+
+Hydra normally propagates the launch node's current directory. Supply `-wdir`
+explicitly so remote ranks do not inherit a directory that exists only on the
+launch node.
+
+```bash
+"$MPICH_HOME/bin/mpiexec" \
+  -launcher ssh \
+  -launcher-exec /usr/bin/ssh \
+  -wdir "$WORKDIR" \
+  -f "$HOSTFILE" \
+  -n 2 \
+  /absolute/path/to/mpi_application
+```
+
+Confirm that every expected host and rank appears before involving MANA.
+
+The native application should execute at least one MPI collective and terminate
+normally.
+
+## 6. Start the coordinator
+
+For an externally launched Hydra job, the coordinator can briefly have zero
+clients before the MPI ranks connect.
+
+Current `mana_coordinator` invokes DMTCP with `--exit-on-last`. A current-main
+workflow can therefore start the underlying coordinator directly without that
+option:
+
+```bash
+mkdir -p \
+  "$WORKDIR" \
+  "$TEST_HOME" \
+  "$CKPTDIR" \
+  "$TMPDIR" \
+  "$LOGDIR"
+
+COORD_LOG="$LOGDIR/coordinator.log"
+
+"$MANA_HOME/bin/dmtcp_coordinator" \
+  --port 7780 \
+  --interval 0 \
+  --ckptdir "$CKPTDIR" \
+  --coord-logfile "$COORD_LOG" \
+  --daemon \
+  --status-file "$STATUS_FILE"
+```
+
+Inspect the generated status file:
+
+```bash
+cat "$STATUS_FILE"
+```
+
+Copy it to the same absolute path on every node when the path is not shared:
+
+```bash
+while IFS= read -r node || [[ -n "$node" ]]; do
+    node="${node%%[[:space:]]*}"
+
+    [[ -z "$node" || "$node" == \#* ]] && continue
+
+    ssh -n "$REMOTE_USER@$node" \
+      "mkdir -p '$TEST_HOME'"
+
+    scp -q \
+      "$STATUS_FILE" \
+      "$REMOTE_USER@$node:$STATUS_FILE" \
+      </dev/null
+done < "$HOSTFILE"
+```
+
+A proposed persistent-coordinator wrapper option can replace the direct
+`dmtcp_coordinator` invocation if accepted.
+
+## 7. Run a finite MANA smoke test
+
+```bash
+"$MPICH_HOME/bin/mpiexec" \
+  -launcher ssh \
+  -launcher-exec /usr/bin/ssh \
+  -wdir "$WORKDIR" \
+  -f "$HOSTFILE" \
+  -n 2 \
+  -genv HOME "$TEST_HOME" \
+  -genv MANA_HOME "$MANA_HOME" \
+  -genv MPICH_HOME "$MPICH_HOME" \
+  -genv PATH "$MANA_HOME/bin:$MPICH_HOME/bin:$PATH" \
+  -genv LD_LIBRARY_PATH "$MANA_HOME/lib:$MANA_HOME/lib/dmtcp:$MPICH_HOME/lib:${LD_LIBRARY_PATH:-}" \
+  "$MANA_HOME/bin/mana_launch" \
+  --ckptdir "$CKPTDIR" \
+  --tmpdir "$TMPDIR" \
+  /absolute/path/to/finite_mpi_application
+```
+
+The finite application should:
+
+- execute at least one MPI collective;
+- print all expected ranks;
+- terminate normally.
+
+Using `TEST_HOME` prevents the test from reading or overwriting the user's
+normal `~/.mana.rc`.
+
+## 8. Launch a long-running MANA application
+
+Launch the longer application with the same Hydra and MANA environment:
+
+```bash
+"$MPICH_HOME/bin/mpiexec" \
+  -launcher ssh \
+  -launcher-exec /usr/bin/ssh \
+  -wdir "$WORKDIR" \
+  -f "$HOSTFILE" \
+  -n 2 \
+  -genv HOME "$TEST_HOME" \
+  -genv MANA_HOME "$MANA_HOME" \
+  -genv MPICH_HOME "$MPICH_HOME" \
+  -genv PATH "$MANA_HOME/bin:$MPICH_HOME/bin:$PATH" \
+  -genv LD_LIBRARY_PATH "$MANA_HOME/lib:$MANA_HOME/lib/dmtcp:$MPICH_HOME/lib:${LD_LIBRARY_PATH:-}" \
+  "$MANA_HOME/bin/mana_launch" \
+  --ckptdir "$CKPTDIR" \
+  --tmpdir "$TMPDIR" \
+  /absolute/path/to/long_running_mpi_application
+```
+
+Save original-execution output separately from restart output so rollback can
+be measured accurately.
+
+Before requesting a checkpoint, wait until:
+
+```bash
+"$MANA_HOME/bin/dmtcp_command" \
+  --coord-host "$(
+    awk '/^Host:/ {print $2; exit}' "$STATUS_FILE"
+  )" \
+  --coord-port "$(
+    awk '/^Port:/ {print $2; exit}' "$STATUS_FILE"
+  )" \
+  --status
+```
+
+reports the expected number of peers.
+
+## 9. Request a blocking checkpoint
+
+Always apply a timeout:
+
+```bash
+coord_host="$(
+  awk '/^Host:/ {print $2; exit}' "$STATUS_FILE"
+)"
+
+coord_port="$(
+  awk '/^Port:/ {print $2; exit}' "$STATUS_FILE"
+)"
+
+timeout \
+  --signal=TERM \
+  --kill-after=20s \
+  300s \
+  "$MANA_HOME/bin/dmtcp_command" \
+  --coord-host "$coord_host" \
+  --coord-port "$coord_port" \
+  --bcheckpoint
+```
+
+A successful command return code is not sufficient. Verify:
+
+- at least one non-empty `.dmtcp` image per rank;
+- no `.tmp` files remain;
+- the coordinator returns to a running state;
+- application output continues after checkpoint creation.
+
+For example:
+
+```bash
+find "$CKPTDIR" \
+  -type f \
+  -name '*.dmtcp' \
+  -size +0c \
+  -print
+```
+
+Reject incomplete checkpoint attempts:
+
+```bash
+find "$CKPTDIR" \
+  -type f \
+  -name '*.tmp' \
+  -print
+```
+
+The final command should produce no output.
+
+## 10. Stop and restart
+
+Stop only the test-owned MPI execution while preserving the checkpoint images.
+
+Start a fresh persistent coordinator and redistribute its status file to:
+
+```text
+$TEST_HOME/.mana.rc
+```
+
+Current-main `mana_restart` validates entries returned from `--restartdir`
+relative to its current working directory. It also replaces the
+`--restartdir DIR` pair with the rank image in place.
+
+Until the restart-directory proposal is accepted:
+
+- use the checkpoint directory as Hydra's working directory;
+- keep `--restartdir` as the final restart option.
+
+```bash
+"$MPICH_HOME/bin/mpiexec" \
+  -launcher ssh \
+  -launcher-exec /usr/bin/ssh \
+  -wdir "$CKPTDIR" \
+  -f "$HOSTFILE" \
+  -n 2 \
+  -genv HOME "$TEST_HOME" \
+  -genv MANA_HOME "$MANA_HOME" \
+  -genv MPICH_HOME "$MPICH_HOME" \
+  -genv PATH "$MANA_HOME/bin:$MPICH_HOME/bin:$PATH" \
+  -genv LD_LIBRARY_PATH "$MANA_HOME/lib:$MANA_HOME/lib/dmtcp:$MPICH_HOME/lib:${LD_LIBRARY_PATH:-}" \
+  -genv DMTCP_LOG_LEVEL trace \
+  "$MANA_HOME/bin/mana_restart" \
+  --verbose \
+  --ckptdir "$CKPTDIR" \
+  --tmpdir "$TMPDIR" \
+  --restartdir "$CKPTDIR"
+```
+
+After the restart-directory fix, restart should work from an unrelated working
+directory and should not depend on option ordering.
+
+## 11. Verify correctness after restart
+
+A useful validation application prints, for every iteration:
+
+```text
+rank
+communicator size
+hostname
+PID
+iteration
+collective result
+```
+
+Verify all of the following:
+
+1. The first post-restart iteration is no greater than the maximum
+   pre-checkpoint iteration.
+2. Post-restart iteration numbers continue increasing.
+3. Every expected rank reconnects.
+4. Collective results match the mathematically expected value.
+5. The application continues making forward progress.
+6. A second checkpoint can be created after restart when chained
+   checkpoint/restart is under test.
+
+## 12. Loader debug symbols
+
+On distributions that install detached loader symbols under GNU build-ID paths,
+identify the loader and its debug file with:
+
+```bash
+loader=/lib64/ld-linux-x86-64.so.2
+real_loader="$(readlink -f "$loader")"
+
+build_id="$(
+  readelf -n "$real_loader" |
+  awk '/Build ID:/ {print $3; exit}'
+)"
+
+debug_file="/usr/lib/debug/.build-id/${build_id:0:2}/${build_id:2}.debug"
+
+printf 'Loader: %s\n' "$real_loader"
+printf 'Debug:  %s\n' "$debug_file"
+
+test -f "$debug_file"
+```
+
+Check the required symbols:
+
+```bash
+readelf -sW "$debug_file" |
+awk '$NF == "mmap" || $NF == "munmap"'
+```
+
+A proposed lower-half change adds native lookup of this standard build-ID
+location.
+
+Do not treat a compatibility symlink created under `/usr/lib/debug` as the
+preferred final upstream solution.
+
+## 13. MPICH/Hydra PMI descriptor handling
+
+In the validated MPICH/Hydra environment, complete checkpoint and restart also
+required DMTCP socket handling to recognize `PMI_FD` alongside the existing
+Hydra descriptor condition.
+
+This dependency changes code inside MANA's DMTCP submodule and should therefore
+be reviewed separately from unrelated MANA changes.
+
+Do not silently modify or commit a dirty DMTCP submodule as part of another
+pull request.
+
+When diagnosing an environment where native MPI and MANA launch succeed but
+checkpoint or restart does not complete, record:
+
+```bash
+env |
+grep -E '^(HYDI_CONTROL_FD|PMI_FD)=' || true
+```
+
+Locate the existing DMTCP Hydra handling:
+
+```bash
+git -C "$MANA_HOME/dmtcp" grep -n -C 5 \
+  'HYDI_CONTROL_FD' \
+  -- '*socketconnlist.cpp'
+```
+
+The validated condition included both:
+
+```cpp
+(getenv("HYDI_CONTROL_FD")) ||
+(getenv("PMI_FD"))
+```
+
+The final ownership of this correction may be:
+
+- a DMTCP upstream change;
+- a temporary MANA-maintained compatibility patch;
+- an equivalent MANA-side solution;
+- another approach preferred by the maintainers.
+
+## 14. Safe cleanup
+
+Avoid broad commands such as:
+
+```text
+pkill -9 -f mana
+killall dmtcp_coordinator
+```
+
+on shared systems.
+
+Record launcher PIDs and match only processes whose command line contains a
+unique test directory.
+
+Stop the coordinator through `dmtcp_command` when possible:
+
+```bash
+"$MANA_HOME/bin/dmtcp_command" \
+  --coord-host "$coord_host" \
+  --coord-port "$coord_port" \
+  --quit
+```
+
+Keep logs, status files, hostfiles, checkpoint images, and generated binaries
+outside the Git working tree.
+
+## 15. Opt-in regression test
+
+When the accompanying multi-node test is available in the checked-out branch
+or release, run:
+
+```bash
+export MANA_HOME=/path/to/built/mana
+export MANA_TEST_MPICH_HOME=/path/to/mpich
+export MANA_TEST_HOSTFILE=/path/to/hosts.txt
+export MANA_TEST_WORKDIR=/absolute/path/on/all/nodes
+export MANA_TEST_REMOTE_USER="$USER"
+
+bash ci/multinode/run-mpich-hydra.sh
+```
+
+The test skips successfully when `MANA_TEST_HOSTFILE` is unset.