diff --git a/.github/workflows/README.md b/.github/workflows/README.md
new file mode 100644
index 00000000..c56be3f2
--- /dev/null
+++ b/.github/workflows/README.md
@@ -0,0 +1,23 @@
+# rust-miniscript workflow notes
+
+We are attempting to run max 20 parallel jobs using GitHub actions (usage limit for free tier).
+
+ref: https://docs.github.com/en/actions/learn-github-actions/usage-limits-billing-and-administration
+
+The minimal/recent lock files are handled by CI (`rust.yml`).
+
+## Jobs
+
+Run from `rust.yml` unless stated otherwise. Total 11 jobs.
+
+1.  `Stable - minimal`
+2.  `Stable - recent`
+3.  `Nightly - minimal`
+4.  `Nightly - recent`
+5.  `MSRV - minimal`
+6.  `Integration - 0.18.0`
+7.  `Integration - 0.18.1`
+8.  `Integration - 0.19.0.1`
+9.  `Integration - 0.19.1`
+10. `Integration - 0.20.0`
+11. `Integration - 0.21.0`
diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 377f3ff2..d75c33fa 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -1,42 +1,91 @@
-on: [push, pull_request]
+---   # rust-bitcoincore-rpc CI: If you edit this file please update README.md
+on:   # yamllint disable-line rule:truthy
+  push:
+    branches:
+      - master
+      - 'test-ci/**'
+  pull_request:
 
 name: Continuous integration
 
 jobs:
-  tests:
-    name: Tests
+  Stable:                       # 2 jobs, one per lock file.
+    name: Test - stable toolchain
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
-        include:
-          - rust: stable
-            env:
-              RUSTFMTCHK: true
-          - rust: nightly
-            env:
-              RUSTFMTCHK: false
-          - rust: 1.56.1
-            env:
-              RUSTFMTCHK: false
+        dep: [minimal, recent]
     steps:
-      - name: Checkout Crate
-        uses: actions/checkout@v2
-      - name: Checkout Toolchain
-        uses: actions-rs/toolchain@v1
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Checkout maintainer tools"
+        uses: actions/checkout@v4
         with:
-          profile: minimal
-          toolchain: ${{ matrix.rust }}
-          override: true
-      - name: Running test script
-        env: ${{ matrix.env }}
-        run: ./contrib/test.sh
+          repository: rust-bitcoin/rust-bitcoin-maintainer-tools
+          rev: b2ac115
+          path: maintainer-tools
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@stable
+      - name: "Set dependencies"
+        run: cp Cargo-${{ matrix.dep }}.lock Cargo.lock
+      - name: "Run test script"
+        run: ./maintainer-tools/ci/run_task.sh stable
 
-  integrations-tests:
-    name: Integration Tests
+  Nightly:                      #  2 jobs, one per lock file.
+    name: Test - nightly toolchain
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
+      matrix:
+        dep: [minimal, recent]
+    steps:
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Checkout maintainer tools"
+        uses: actions/checkout@v4
+        with:
+          repository: rust-bitcoin/rust-bitcoin-maintainer-tools
+          rev: b2ac115
+          path: maintainer-tools
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@nightly
+      - name: "Set dependencies"
+        run: cp Cargo-${{ matrix.dep }}.lock Cargo.lock
+      - name: "Run test script"
+        run: ./maintainer-tools/ci/run_task.sh nightly
+
+  MSRV:          # 2 jobs, one per lock file.
+    name: Test - 1.56.1 toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        dep: [minimal, recent]
+    steps:
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Checkout maintainer tools"
+        uses: actions/checkout@v4
+        with:
+          repository: rust-bitcoin/rust-bitcoin-maintainer-tools
+          rev: b2ac115
+          path: maintainer-tools
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: "1.56.1"
+      - name: "Set dependencies"
+        run: cp Cargo-${{ matrix.dep }}.lock Cargo.lock
+      - name: "Run test script"
+        run: ./maintainer-tools/ci/run_task.sh msrv
+
+  Integration:                  # 1 job for each Bitcoin Core version.
+    name: Integration tests - stable toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
       matrix:
-        rust: [stable]
         bitcoinversion:
           [
             "0.18.0",
@@ -48,15 +97,11 @@ jobs:
             "0.21.0",
           ]
     steps:
-      - name: Checkout Crate
-        uses: actions/checkout@v2
-      - name: Checkout Toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: ${{ matrix.rust }}
-          override: true
-      - name: Running test script
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@stable
+      - name: "Run integration tests"
         env:
           BITCOINVERSION: ${{ matrix.bitcoinversion }}
-        run: ./contrib/test.sh
+        run: ./contrib/integration_test.sh
diff --git a/Cargo-minimal.lock b/Cargo-minimal.lock
new file mode 100644
index 00000000..ee88a8ee
--- /dev/null
+++ b/Cargo-minimal.lock
@@ -0,0 +1,525 @@
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diff --git a/client/contrib/test_vars.sh b/client/contrib/test_vars.sh
new file mode 100644
index 00000000..6ff05eab
--- /dev/null
+++ b/client/contrib/test_vars.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+# Test all these features with "std" enabled.
+FEATURES_WITH_STD=""
+
+# Test all these features without "std" enabled.
+FEATURES_WITHOUT_STD="verifymessage"
+
+# Run these examples.
+EXAMPLES="retry_client:verifymessage"
diff --git a/contrib/crates.sh b/contrib/crates.sh
new file mode 100755
index 00000000..88955c6b
--- /dev/null
+++ b/contrib/crates.sh
@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+# Crates in this workspace to test (excl. fuzz an integration-tests).
+CRATES=("json" "client")
diff --git a/contrib/integration_test.sh b/contrib/integration_test.sh
new file mode 100755
index 00000000..1522d404
--- /dev/null
+++ b/contrib/integration_test.sh
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+#
+# Run the integration test optionally downloading Bitcoin Core binary if BITCOINVERSION is set.
+
+set -euo pipefail
+
+REPO_DIR=$(git rev-parse --show-toplevel)
+
+# Make all cargo invocations verbose.
+export CARGO_TERM_VERBOSE=true
+
+main() {
+    # If a specific version of Bitcoin Core is set then download the binary.
+    if [ -n "${BITCOINVERSION+x}" ]; then
+        download_binary
+    fi
+
+    need_cmd bitcoind
+
+    cd integration_test
+    ./run.sh
+}
+
+download_binary() {
+    wget https://bitcoincore.org/bin/bitcoin-core-$BITCOINVERSION/bitcoin-$BITCOINVERSION-x86_64-linux-gnu.tar.gz
+    tar -xzvf bitcoin-$BITCOINVERSION-x86_64-linux-gnu.tar.gz
+    export PATH=$PATH:$(pwd)/bitcoin-$BITCOINVERSION/bin
+}
+
+err() {
+    echo "$1" >&2
+    exit 1
+}
+
+need_cmd() {
+    if ! command -v "$1" > /dev/null 2>&1
+    then err "need '$1' (command not found)"
+    fi
+}
+
+#
+# Main script
+#
+main "$@"
+exit 0
diff --git a/contrib/test.sh b/contrib/test.sh
deleted file mode 100755
index 2aa5a279..00000000
--- a/contrib/test.sh
+++ /dev/null
@@ -1,38 +0,0 @@
-
-set -xe
-
-MSRV="1\.56"
-
-# Just echo all the relevant env vars to help debug Travis.
-echo "RUSTFMTCHECK: \"$RUSTFMTCHECK\""
-echo "BITCOINVERSION: \"$BITCOINVERSION\""
-echo "PATH: \"$PATH\""
-
-if [ -n "$RUSTFMTCHECK" ]; then
-  rustup component add rustfmt
-  cargo fmt --all -- --check
-fi
-
-# Test pinned versions.
-if cargo --version | grep ${MSRV}; then
-    cargo update -p tempfile --precise 3.3.0
-    cargo update -p cc --precise 1.0.79
-    cargo update -p log --precise 0.4.18
-    cargo update -p serde_json --precise 1.0.96
-    cargo update -p serde --precise 1.0.156
-fi
-
-# Integration test.
-if [ -n "$BITCOINVERSION" ]; then
-    wget https://bitcoincore.org/bin/bitcoin-core-$BITCOINVERSION/bitcoin-$BITCOINVERSION-x86_64-linux-gnu.tar.gz
-    tar -xzvf bitcoin-$BITCOINVERSION-x86_64-linux-gnu.tar.gz
-    export PATH=$PATH:$(pwd)/bitcoin-$BITCOINVERSION/bin
-    cd integration_test
-    ./run.sh
-    exit 0
-else
-  # Regular build/unit test.
-  cargo build --verbose
-  cargo test --verbose
-  cargo build --verbose --examples
-fi
diff --git a/json/Cargo.toml b/json/Cargo.toml
index 8f3d67cc..0bb6b4d6 100644
--- a/json/Cargo.toml
+++ b/json/Cargo.toml
@@ -24,3 +24,4 @@ serde = { version = "1", features = [ "derive" ] }
 serde_json = "1"
 
 bitcoin = { version = "0.31.0", features = ["serde", "rand-std"]}
+
diff --git a/json/contrib/test_vars.sh b/json/contrib/test_vars.sh
new file mode 100644
index 00000000..0c25edc7
--- /dev/null
+++ b/json/contrib/test_vars.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+# Test all these features with "std" enabled.
+FEATURES_WITH_STD=""
+
+# Test all these features without "std" enabled.
+FEATURES_WITHOUT_STD=""
+
+# Run these examples.
+EXAMPLES=""