diff --git a/src/libstore-test-support/include/nix/store/tests/protocol.hh b/src/libstore-test-support/include/nix/store/tests/protocol.hh
index 5b57c6585..0f774df0e 100644
--- a/src/libstore-test-support/include/nix/store/tests/protocol.hh
+++ b/src/libstore-test-support/include/nix/store/tests/protocol.hh
@@ -6,6 +6,7 @@
 
 #include "nix/store/tests/libstore.hh"
 #include "nix/util/tests/characterization.hh"
+#include "nix/util/tests/json-characterization.hh"
 
 namespace nix {
 
@@ -16,12 +17,30 @@ class ProtoTest : public CharacterizationTest
 
     std::filesystem::path goldenMaster(std::string_view testStem) const override
     {
-        return unitTestData / (std::string{testStem + ".bin"});
+        return unitTestData / testStem;
     }
 
 public:
     Path storeDir = "/nix/store";
     StoreDirConfig store{storeDir};
+
+    /**
+     * Golden test for `T` JSON reading
+     */
+    template<typename T>
+    void readJsonTest(PathView testStem, const T & expected)
+    {
+        nix::readJsonTest(*this, testStem, expected);
+    }
+
+    /**
+     * Golden test for `T` JSON write
+     */
+    template<typename T>
+    void writeJsonTest(PathView testStem, const T & decoded)
+    {
+        nix::writeJsonTest(*this, testStem, decoded);
+    }
 };
 
 template<class Proto, const char * protocolDir>
@@ -34,7 +53,7 @@ public:
     template<typename T>
     void readProtoTest(PathView testStem, typename Proto::Version version, T expected)
     {
-        CharacterizationTest::readTest(testStem, [&](const auto & encoded) {
+        CharacterizationTest::readTest(std::string{testStem + ".bin"}, [&](const auto & encoded) {
             T got = ({
                 StringSource from{encoded};
                 Proto::template Serialise<T>::read(
@@ -55,7 +74,7 @@ public:
     template<typename T>
     void writeProtoTest(PathView testStem, typename Proto::Version version, const T & decoded)
     {
-        CharacterizationTest::writeTest(testStem, [&]() {
+        CharacterizationTest::writeTest(std::string{testStem + ".bin"}, [&]() {
             StringSink to;
             Proto::template Serialise<T>::write(
                 this->store,
@@ -69,14 +88,25 @@ public:
     }
 };
 
-#define VERSIONED_CHARACTERIZATION_TEST(FIXTURE, NAME, STEM, VERSION, VALUE) \
-    TEST_F(FIXTURE, NAME##_read)                                             \
-    {                                                                        \
-        readProtoTest(STEM, VERSION, VALUE);                                 \
-    }                                                                        \
-    TEST_F(FIXTURE, NAME##_write)                                            \
-    {                                                                        \
-        writeProtoTest(STEM, VERSION, VALUE);                                \
+#define VERSIONED_CHARACTERIZATION_TEST_NO_JSON(FIXTURE, NAME, STEM, VERSION, VALUE) \
+    TEST_F(FIXTURE, NAME##_read)                                                     \
+    {                                                                                \
+        readProtoTest(STEM, VERSION, VALUE);                                         \
+    }                                                                                \
+    TEST_F(FIXTURE, NAME##_write)                                                    \
+    {                                                                                \
+        writeProtoTest(STEM, VERSION, VALUE);                                        \
+    }
+
+#define VERSIONED_CHARACTERIZATION_TEST(FIXTURE, NAME, STEM, VERSION, VALUE)     \
+    VERSIONED_CHARACTERIZATION_TEST_NO_JSON(FIXTURE, NAME, STEM, VERSION, VALUE) \
+    TEST_F(FIXTURE, NAME##_json_read)                                            \
+    {                                                                            \
+        readJsonTest(STEM, VALUE);                                               \
+    }                                                                            \
+    TEST_F(FIXTURE, NAME##_json_write)                                           \
+    {                                                                            \
+        writeJsonTest(STEM, VALUE);                                              \
     }
 
 } // namespace nix
diff --git a/src/libstore-tests/common-protocol.cc b/src/libstore-tests/common-protocol.cc
index 7c40e8cdb..fa676eb7f 100644
--- a/src/libstore-tests/common-protocol.cc
+++ b/src/libstore-tests/common-protocol.cc
@@ -3,6 +3,7 @@
 #include <nlohmann/json.hpp>
 #include <gtest/gtest.h>
 
+#include "nix/util/json-utils.hh"
 #include "nix/store/common-protocol.hh"
 #include "nix/store/common-protocol-impl.hh"
 #include "nix/store/build-result.hh"
@@ -22,7 +23,7 @@ public:
     template<typename T>
     void readProtoTest(PathView testStem, const T & expected)
     {
-        CharacterizationTest::readTest(testStem, [&](const auto & encoded) {
+        CharacterizationTest::readTest(std::string{testStem + ".bin"}, [&](const auto & encoded) {
             T got = ({
                 StringSource from{encoded};
                 CommonProto::Serialise<T>::read(store, CommonProto::ReadConn{.from = from});
@@ -38,7 +39,7 @@ public:
     template<typename T>
     void writeProtoTest(PathView testStem, const T & decoded)
     {
-        CharacterizationTest::writeTest(testStem, [&]() -> std::string {
+        CharacterizationTest::writeTest(std::string{testStem + ".bin"}, [&]() -> std::string {
             StringSink to;
             CommonProto::Serialise<T>::write(store, CommonProto::WriteConn{.to = to}, decoded);
             return to.s;
@@ -54,6 +55,14 @@ public:
     TEST_F(CommonProtoTest, NAME##_write)        \
     {                                            \
         writeProtoTest(STEM, VALUE);             \
+    }                                            \
+    TEST_F(CommonProtoTest, NAME##_json_read)    \
+    {                                            \
+        readJsonTest(STEM, VALUE);               \
+    }                                            \
+    TEST_F(CommonProtoTest, NAME##_json_write)   \
+    {                                            \
+        writeJsonTest(STEM, VALUE);              \
     }
 
 CHARACTERIZATION_TEST(
diff --git a/src/libstore-tests/data/common-protocol/content-address.json b/src/libstore-tests/data/common-protocol/content-address.json
new file mode 100644
index 000000000..9a0d57154
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/content-address.json
@@ -0,0 +1,26 @@
+[
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+    },
+    "method": "text"
+  },
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  },
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+    },
+    "method": "nar"
+  }
+]
diff --git a/src/libstore-tests/data/common-protocol/drv-output.json b/src/libstore-tests/data/common-protocol/drv-output.json
new file mode 100644
index 000000000..2668d70c9
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/drv-output.json
@@ -0,0 +1,4 @@
+[
+  "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+  "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux"
+]
diff --git a/src/libstore-tests/data/common-protocol/optional-content-address.json b/src/libstore-tests/data/common-protocol/optional-content-address.json
new file mode 100644
index 000000000..6cdaa59a5
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/optional-content-address.json
@@ -0,0 +1,11 @@
+[
+  null,
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  }
+]
diff --git a/src/libstore-tests/data/common-protocol/optional-store-path.json b/src/libstore-tests/data/common-protocol/optional-store-path.json
new file mode 100644
index 000000000..58519a4d2
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/optional-store-path.json
@@ -0,0 +1,4 @@
+[
+  null,
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/common-protocol/realisation.json b/src/libstore-tests/data/common-protocol/realisation.json
new file mode 100644
index 000000000..c784e500d
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/realisation.json
@@ -0,0 +1,22 @@
+[
+  {
+    "dependentRealisations": {},
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  },
+  {
+    "dependentRealisations": {
+      "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo"
+    },
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  }
+]
diff --git a/src/libstore-tests/data/common-protocol/set.json b/src/libstore-tests/data/common-protocol/set.json
new file mode 100644
index 000000000..acd123082
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/set.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "bar",
+    "foo"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/data/common-protocol/store-path.json b/src/libstore-tests/data/common-protocol/store-path.json
new file mode 100644
index 000000000..16459245b
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/store-path.json
@@ -0,0 +1,4 @@
+[
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/common-protocol/string.json b/src/libstore-tests/data/common-protocol/string.json
new file mode 100644
index 000000000..d3db4f3b4
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/string.json
@@ -0,0 +1,7 @@
+[
+  "",
+  "hi",
+  "white rabbit",
+  "大白兔",
+  "oh no "
+]
diff --git a/src/libstore-tests/data/common-protocol/vector.json b/src/libstore-tests/data/common-protocol/vector.json
new file mode 100644
index 000000000..2b8cc1b3a
--- /dev/null
+++ b/src/libstore-tests/data/common-protocol/vector.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "foo",
+    "bar"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/data/serve-protocol/build-result-2.2.json b/src/libstore-tests/data/serve-protocol/build-result-2.2.json
new file mode 100644
index 000000000..b52b6fad5
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/build-result-2.2.json
@@ -0,0 +1,28 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "not deterministic",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "builtOutputs": {},
+    "startTime": 0,
+    "status": "built",
+    "stopTime": 0,
+    "success": true,
+    "timesBuilt": 0
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/build-result-2.3.json b/src/libstore-tests/data/serve-protocol/build-result-2.3.json
new file mode 100644
index 000000000..66b3ca082
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/build-result-2.3.json
@@ -0,0 +1,28 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": true,
+    "startTime": 30,
+    "status": "not deterministic",
+    "stopTime": 50,
+    "success": false,
+    "timesBuilt": 3
+  },
+  {
+    "builtOutputs": {},
+    "startTime": 30,
+    "status": "built",
+    "stopTime": 50,
+    "success": true,
+    "timesBuilt": 0
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/build-result-2.6.json b/src/libstore-tests/data/serve-protocol/build-result-2.6.json
new file mode 100644
index 000000000..b64f1109d
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/build-result-2.6.json
@@ -0,0 +1,41 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": true,
+    "startTime": 30,
+    "status": "not deterministic",
+    "stopTime": 50,
+    "success": false,
+    "timesBuilt": 3
+  },
+  {
+    "builtOutputs": {
+      "bar": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!bar",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+        "signatures": []
+      },
+      "foo": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!foo",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+        "signatures": []
+      }
+    },
+    "startTime": 30,
+    "status": "built",
+    "stopTime": 50,
+    "success": true,
+    "timesBuilt": 1
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/content-address.json b/src/libstore-tests/data/serve-protocol/content-address.json
new file mode 100644
index 000000000..9a0d57154
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/content-address.json
@@ -0,0 +1,26 @@
+[
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+    },
+    "method": "text"
+  },
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  },
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+    },
+    "method": "nar"
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/drv-output.json b/src/libstore-tests/data/serve-protocol/drv-output.json
new file mode 100644
index 000000000..2668d70c9
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/drv-output.json
@@ -0,0 +1,4 @@
+[
+  "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+  "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux"
+]
diff --git a/src/libstore-tests/data/serve-protocol/optional-content-address.json b/src/libstore-tests/data/serve-protocol/optional-content-address.json
new file mode 100644
index 000000000..6cdaa59a5
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/optional-content-address.json
@@ -0,0 +1,11 @@
+[
+  null,
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/optional-store-path.json b/src/libstore-tests/data/serve-protocol/optional-store-path.json
new file mode 100644
index 000000000..58519a4d2
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/optional-store-path.json
@@ -0,0 +1,4 @@
+[
+  null,
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/serve-protocol/realisation.json b/src/libstore-tests/data/serve-protocol/realisation.json
new file mode 100644
index 000000000..c784e500d
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/realisation.json
@@ -0,0 +1,22 @@
+[
+  {
+    "dependentRealisations": {},
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  },
+  {
+    "dependentRealisations": {
+      "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo"
+    },
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/set.json b/src/libstore-tests/data/serve-protocol/set.json
new file mode 100644
index 000000000..acd123082
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/set.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "bar",
+    "foo"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/data/serve-protocol/store-path.json b/src/libstore-tests/data/serve-protocol/store-path.json
new file mode 100644
index 000000000..16459245b
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/store-path.json
@@ -0,0 +1,4 @@
+[
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/serve-protocol/string.json b/src/libstore-tests/data/serve-protocol/string.json
new file mode 100644
index 000000000..d3db4f3b4
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/string.json
@@ -0,0 +1,7 @@
+[
+  "",
+  "hi",
+  "white rabbit",
+  "大白兔",
+  "oh no "
+]
diff --git a/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.3.json b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.3.json
new file mode 100644
index 000000000..3b532c0e8
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.3.json
@@ -0,0 +1,32 @@
+[
+  {
+    "ca": null,
+    "deriver": null,
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
+    },
+    "narSize": 34878,
+    "references": [],
+    "registrationTime": null,
+    "signatures": [],
+    "ultimate": false
+  },
+  {
+    "ca": null,
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
+    },
+    "narSize": 34878,
+    "references": [
+      "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo.drv"
+    ],
+    "registrationTime": null,
+    "signatures": [],
+    "ultimate": false
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.4.json b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.4.json
new file mode 100644
index 000000000..07de33932
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.4.json
@@ -0,0 +1,45 @@
+[
+  {
+    "ca": null,
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "references": [
+      "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo.drv"
+    ],
+    "registrationTime": null,
+    "signatures": [],
+    "ultimate": false
+  },
+  {
+    "ca": {
+      "hash": {
+        "algorithm": "sha256",
+        "format": "base64",
+        "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      },
+      "method": "nar"
+    },
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "references": [
+      "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+      "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    ],
+    "registrationTime": null,
+    "signatures": [
+      "fake-sig-1",
+      "fake-sig-2"
+    ],
+    "ultimate": false
+  }
+]
diff --git a/src/libstore-tests/data/serve-protocol/vector.json b/src/libstore-tests/data/serve-protocol/vector.json
new file mode 100644
index 000000000..2b8cc1b3a
--- /dev/null
+++ b/src/libstore-tests/data/serve-protocol/vector.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "foo",
+    "bar"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/data/worker-protocol/build-mode.json b/src/libstore-tests/data/worker-protocol/build-mode.json
new file mode 100644
index 000000000..2ef158f87
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/build-mode.json
@@ -0,0 +1,5 @@
+[
+  0,
+  1,
+  2
+]
diff --git a/src/libstore-tests/data/worker-protocol/build-result-1.27.json b/src/libstore-tests/data/worker-protocol/build-result-1.27.json
new file mode 100644
index 000000000..b52b6fad5
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/build-result-1.27.json
@@ -0,0 +1,28 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "not deterministic",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "builtOutputs": {},
+    "startTime": 0,
+    "status": "built",
+    "stopTime": 0,
+    "success": true,
+    "timesBuilt": 0
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/build-result-1.28.json b/src/libstore-tests/data/worker-protocol/build-result-1.28.json
new file mode 100644
index 000000000..ce6507452
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/build-result-1.28.json
@@ -0,0 +1,41 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "not deterministic",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "builtOutputs": {
+      "bar": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!bar",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+        "signatures": []
+      },
+      "foo": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!foo",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+        "signatures": []
+      }
+    },
+    "startTime": 0,
+    "status": "built",
+    "stopTime": 0,
+    "success": true,
+    "timesBuilt": 0
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/build-result-1.29.json b/src/libstore-tests/data/worker-protocol/build-result-1.29.json
new file mode 100644
index 000000000..b64f1109d
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/build-result-1.29.json
@@ -0,0 +1,41 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": true,
+    "startTime": 30,
+    "status": "not deterministic",
+    "stopTime": 50,
+    "success": false,
+    "timesBuilt": 3
+  },
+  {
+    "builtOutputs": {
+      "bar": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!bar",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+        "signatures": []
+      },
+      "foo": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!foo",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+        "signatures": []
+      }
+    },
+    "startTime": 30,
+    "status": "built",
+    "stopTime": 50,
+    "success": true,
+    "timesBuilt": 1
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/build-result-1.37.json b/src/libstore-tests/data/worker-protocol/build-result-1.37.json
new file mode 100644
index 000000000..7edc02f44
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/build-result-1.37.json
@@ -0,0 +1,43 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": true,
+    "startTime": 30,
+    "status": "not deterministic",
+    "stopTime": 50,
+    "success": false,
+    "timesBuilt": 3
+  },
+  {
+    "builtOutputs": {
+      "bar": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!bar",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+        "signatures": []
+      },
+      "foo": {
+        "dependentRealisations": {},
+        "id": "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!foo",
+        "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+        "signatures": []
+      }
+    },
+    "cpuSystem": 604000000,
+    "cpuUser": 500000000,
+    "startTime": 30,
+    "status": "built",
+    "stopTime": 50,
+    "success": true,
+    "timesBuilt": 1
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/content-address.json b/src/libstore-tests/data/worker-protocol/content-address.json
new file mode 100644
index 000000000..9a0d57154
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/content-address.json
@@ -0,0 +1,26 @@
+[
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+    },
+    "method": "text"
+  },
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  },
+  {
+    "hash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+    },
+    "method": "nar"
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/derived-path-1.29.json b/src/libstore-tests/data/worker-protocol/derived-path-1.29.json
new file mode 100644
index 000000000..f0efe4a35
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/derived-path-1.29.json
@@ -0,0 +1,16 @@
+[
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+  {
+    "drvPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "outputs": [
+      "*"
+    ]
+  },
+  {
+    "drvPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "outputs": [
+      "x",
+      "y"
+    ]
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/derived-path-1.30.json b/src/libstore-tests/data/worker-protocol/derived-path-1.30.json
new file mode 100644
index 000000000..7a67e4761
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/derived-path-1.30.json
@@ -0,0 +1,17 @@
+[
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv",
+  {
+    "drvPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "outputs": [
+      "*"
+    ]
+  },
+  {
+    "drvPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "outputs": [
+      "x",
+      "y"
+    ]
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/drv-output.json b/src/libstore-tests/data/worker-protocol/drv-output.json
new file mode 100644
index 000000000..2668d70c9
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/drv-output.json
@@ -0,0 +1,4 @@
+[
+  "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+  "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux"
+]
diff --git a/src/libstore-tests/data/worker-protocol/keyed-build-result-1.29.json b/src/libstore-tests/data/worker-protocol/keyed-build-result-1.29.json
new file mode 100644
index 000000000..2b23eb08c
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/keyed-build-result-1.29.json
@@ -0,0 +1,27 @@
+[
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": false,
+    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-xxx",
+    "startTime": 0,
+    "status": "output rejected",
+    "stopTime": 0,
+    "success": false,
+    "timesBuilt": 0
+  },
+  {
+    "errorMsg": "no idea why",
+    "isNonDeterministic": true,
+    "path": {
+      "drvPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+      "outputs": [
+        "out"
+      ]
+    },
+    "startTime": 30,
+    "status": "not deterministic",
+    "stopTime": 50,
+    "success": false,
+    "timesBuilt": 3
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/optional-content-address.json b/src/libstore-tests/data/worker-protocol/optional-content-address.json
new file mode 100644
index 000000000..6cdaa59a5
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/optional-content-address.json
@@ -0,0 +1,11 @@
+[
+  null,
+  {
+    "hash": {
+      "algorithm": "sha1",
+      "format": "base64",
+      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+    },
+    "method": "flat"
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/optional-store-path.json b/src/libstore-tests/data/worker-protocol/optional-store-path.json
new file mode 100644
index 000000000..58519a4d2
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/optional-store-path.json
@@ -0,0 +1,4 @@
+[
+  null,
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/worker-protocol/optional-trusted-flag.json b/src/libstore-tests/data/worker-protocol/optional-trusted-flag.json
new file mode 100644
index 000000000..2f3c092f8
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/optional-trusted-flag.json
@@ -0,0 +1,5 @@
+[
+  null,
+  true,
+  false
+]
diff --git a/src/libstore-tests/data/worker-protocol/realisation.json b/src/libstore-tests/data/worker-protocol/realisation.json
new file mode 100644
index 000000000..c784e500d
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/realisation.json
@@ -0,0 +1,22 @@
+[
+  {
+    "dependentRealisations": {},
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  },
+  {
+    "dependentRealisations": {
+      "sha256:6f869f9ea2823bda165e06076fd0de4366dead2c0e8d2dbbad277d4f15c373f5!quux": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo"
+    },
+    "id": "sha256:15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527!baz",
+    "outPath": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+    "signatures": [
+      "asdf",
+      "qwer"
+    ]
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/set.json b/src/libstore-tests/data/worker-protocol/set.json
new file mode 100644
index 000000000..acd123082
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/set.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "bar",
+    "foo"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/data/worker-protocol/store-path.json b/src/libstore-tests/data/worker-protocol/store-path.json
new file mode 100644
index 000000000..16459245b
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/store-path.json
@@ -0,0 +1,4 @@
+[
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo",
+  "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo-bar"
+]
diff --git a/src/libstore-tests/data/worker-protocol/string.json b/src/libstore-tests/data/worker-protocol/string.json
new file mode 100644
index 000000000..d3db4f3b4
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/string.json
@@ -0,0 +1,7 @@
+[
+  "",
+  "hi",
+  "white rabbit",
+  "大白兔",
+  "oh no "
+]
diff --git a/src/libstore-tests/data/worker-protocol/unkeyed-valid-path-info-1.15.json b/src/libstore-tests/data/worker-protocol/unkeyed-valid-path-info-1.15.json
new file mode 100644
index 000000000..b123a5b8f
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/unkeyed-valid-path-info-1.15.json
@@ -0,0 +1,32 @@
+[
+  {
+    "ca": null,
+    "deriver": null,
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "references": [],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": false
+  },
+  {
+    "ca": null,
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "references": [
+      "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo.drv"
+    ],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": false
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/valid-path-info-1.15.json b/src/libstore-tests/data/worker-protocol/valid-path-info-1.15.json
new file mode 100644
index 000000000..9e398e82e
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/valid-path-info-1.15.json
@@ -0,0 +1,35 @@
+[
+  {
+    "ca": null,
+    "deriver": null,
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "references": [],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": false
+  },
+  {
+    "ca": null,
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "references": [
+      "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+      "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo"
+    ],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": false
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/valid-path-info-1.16.json b/src/libstore-tests/data/worker-protocol/valid-path-info-1.16.json
new file mode 100644
index 000000000..339ef17c0
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/valid-path-info-1.16.json
@@ -0,0 +1,63 @@
+[
+  {
+    "ca": null,
+    "deriver": null,
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "references": [],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": true
+  },
+  {
+    "ca": null,
+    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+    "references": [
+      "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+      "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo"
+    ],
+    "registrationTime": 23423,
+    "signatures": [
+      "fake-sig-1",
+      "fake-sig-2"
+    ],
+    "ultimate": false
+  },
+  {
+    "ca": {
+      "hash": {
+        "algorithm": "sha256",
+        "format": "base64",
+        "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      },
+      "method": "nar"
+    },
+    "deriver": null,
+    "narHash": {
+      "algorithm": "sha256",
+      "format": "base64",
+      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    },
+    "narSize": 34878,
+    "path": "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo",
+    "references": [
+      "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
+      "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
+    ],
+    "registrationTime": 23423,
+    "signatures": [],
+    "ultimate": false
+  }
+]
diff --git a/src/libstore-tests/data/worker-protocol/vector.json b/src/libstore-tests/data/worker-protocol/vector.json
new file mode 100644
index 000000000..2b8cc1b3a
--- /dev/null
+++ b/src/libstore-tests/data/worker-protocol/vector.json
@@ -0,0 +1,22 @@
+[
+  [],
+  [
+    ""
+  ],
+  [
+    "",
+    "foo",
+    "bar"
+  ],
+  [
+    [],
+    [
+      ""
+    ],
+    [
+      "",
+      "1",
+      "2"
+    ]
+  ]
+]
diff --git a/src/libstore-tests/serve-protocol.cc b/src/libstore-tests/serve-protocol.cc
index a7b69821c..8d26c8241 100644
--- a/src/libstore-tests/serve-protocol.cc
+++ b/src/libstore-tests/serve-protocol.cc
@@ -4,6 +4,7 @@
 #include <nlohmann/json.hpp>
 #include <gtest/gtest.h>
 
+#include "nix/util/json-utils.hh"
 #include "nix/store/serve-protocol.hh"
 #include "nix/store/serve-protocol-impl.hh"
 #include "nix/store/serve-protocol-connection.hh"
@@ -334,7 +335,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         }),
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     ServeProtoTest,
     build_options_2_1,
     "build-options-2.1",
@@ -344,7 +345,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         .buildTimeout = 6,
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     ServeProtoTest,
     build_options_2_2,
     "build-options-2.2",
@@ -355,7 +356,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         .maxLogSize = 7,
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     ServeProtoTest,
     build_options_2_3,
     "build-options-2.3",
@@ -368,7 +369,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         .enforceDeterminism = true,
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     ServeProtoTest,
     build_options_2_7,
     "build-options-2.7",
diff --git a/src/libstore-tests/worker-protocol.cc b/src/libstore-tests/worker-protocol.cc
index 8f70e937b..f1b639c77 100644
--- a/src/libstore-tests/worker-protocol.cc
+++ b/src/libstore-tests/worker-protocol.cc
@@ -4,6 +4,7 @@
 #include <nlohmann/json.hpp>
 #include <gtest/gtest.h>
 
+#include "nix/util/json-utils.hh"
 #include "nix/store/worker-protocol.hh"
 #include "nix/store/worker-protocol-connection.hh"
 #include "nix/store/worker-protocol-impl.hh"
@@ -649,7 +650,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         },
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     WorkerProtoTest,
     clientHandshakeInfo_1_30,
     "client-handshake-info_1_30",
@@ -658,7 +659,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         {},
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     WorkerProtoTest,
     clientHandshakeInfo_1_33,
     "client-handshake-info_1_33",
@@ -672,7 +673,7 @@ VERSIONED_CHARACTERIZATION_TEST(
         },
     }))
 
-VERSIONED_CHARACTERIZATION_TEST(
+VERSIONED_CHARACTERIZATION_TEST_NO_JSON(
     WorkerProtoTest,
     clientHandshakeInfo_1_35,
     "client-handshake-info_1_35",
diff --git a/src/libstore/build-result.cc b/src/libstore/build-result.cc
index e3d9e9085..f4bc8ab33 100644
--- a/src/libstore/build-result.cc
+++ b/src/libstore/build-result.cc
@@ -153,4 +153,20 @@ BuildResult adl_serializer<BuildResult>::from_json(const json & _json)
     return br;
 }
 
+KeyedBuildResult adl_serializer<KeyedBuildResult>::from_json(const json & json0)
+{
+    auto json = getObject(json0);
+
+    return KeyedBuildResult{
+        adl_serializer<BuildResult>::from_json(json0),
+        valueAt(json, "path"),
+    };
+}
+
+void adl_serializer<KeyedBuildResult>::to_json(json & json, const KeyedBuildResult & kbr)
+{
+    adl_serializer<BuildResult>::to_json(json, kbr);
+    json["path"] = kbr.path;
+}
+
 } // namespace nlohmann
diff --git a/src/libstore/include/nix/store/build-result.hh b/src/libstore/include/nix/store/build-result.hh
index 4739232f8..96134791b 100644
--- a/src/libstore/include/nix/store/build-result.hh
+++ b/src/libstore/include/nix/store/build-result.hh
@@ -178,3 +178,4 @@ struct KeyedBuildResult : BuildResult
 } // namespace nix
 
 JSON_IMPL(nix::BuildResult)
+JSON_IMPL(nix::KeyedBuildResult)
diff --git a/src/libstore/include/nix/store/path-info.hh b/src/libstore/include/nix/store/path-info.hh
index 8f6115b73..a64e8458d 100644
--- a/src/libstore/include/nix/store/path-info.hh
+++ b/src/libstore/include/nix/store/path-info.hh
@@ -197,3 +197,4 @@ using ValidPathInfos = std::map<StorePath, ValidPathInfo>;
 } // namespace nix
 
 JSON_IMPL(nix::UnkeyedValidPathInfo)
+JSON_IMPL(nix::ValidPathInfo)
diff --git a/src/libstore/include/nix/store/realisation.hh b/src/libstore/include/nix/store/realisation.hh
index e8a71862e..af0e4aefd 100644
--- a/src/libstore/include/nix/store/realisation.hh
+++ b/src/libstore/include/nix/store/realisation.hh
@@ -182,5 +182,6 @@ public:
 
 } // namespace nix
 
+JSON_IMPL(nix::DrvOutput)
 JSON_IMPL(nix::UnkeyedRealisation)
 JSON_IMPL(nix::Realisation)
diff --git a/src/libstore/include/nix/store/store-api.hh b/src/libstore/include/nix/store/store-api.hh
index c57eff1f0..4c0b156fa 100644
--- a/src/libstore/include/nix/store/store-api.hh
+++ b/src/libstore/include/nix/store/store-api.hh
@@ -1004,4 +1004,10 @@ const ContentAddress * getDerivationCA(const BasicDerivation & drv);
 std::map<DrvOutput, StorePath>
 drvOutputReferences(Store & store, const Derivation & drv, const StorePath & outputPath, Store * evalStore = nullptr);
 
+template<>
+struct json_avoids_null<TrustedFlag> : std::true_type
+{};
+
 } // namespace nix
+
+JSON_IMPL(nix::TrustedFlag)
diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index 8b2a7287e..ea0c8a3c2 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -10,6 +10,7 @@
 #include "nix/util/closure.hh"
 #include "nix/store/filetransfer.hh"
 #include "nix/util/strings.hh"
+#include "nix/util/json-utils.hh"
 
 #include <boost/unordered/unordered_flat_set.hpp>
 
@@ -479,3 +480,19 @@ OutputPathMap resolveDerivedPath(Store & store, const DerivedPath::Built & bfd)
 }
 
 } // namespace nix
+
+namespace nlohmann {
+
+using namespace nix;
+
+TrustedFlag adl_serializer<TrustedFlag>::from_json(const json & json)
+{
+    return getBoolean(json) ? TrustedFlag::Trusted : TrustedFlag::NotTrusted;
+}
+
+void adl_serializer<TrustedFlag>::to_json(json & json, const TrustedFlag & trustedFlag)
+{
+    json = static_cast<bool>(trustedFlag);
+}
+
+} // namespace nlohmann
diff --git a/src/libstore/path-info.cc b/src/libstore/path-info.cc
index 79c1dc8ac..838bab19f 100644
--- a/src/libstore/path-info.cc
+++ b/src/libstore/path-info.cc
@@ -249,4 +249,20 @@ void adl_serializer<UnkeyedValidPathInfo>::to_json(json & json, const UnkeyedVal
     json = c.toJSON(nullptr, true);
 }
 
+ValidPathInfo adl_serializer<ValidPathInfo>::from_json(const json & json0)
+{
+    auto json = getObject(json0);
+
+    return ValidPathInfo{
+        valueAt(json, "path"),
+        adl_serializer<UnkeyedValidPathInfo>::from_json(json0),
+    };
+}
+
+void adl_serializer<ValidPathInfo>::to_json(json & json, const ValidPathInfo & v)
+{
+    adl_serializer<UnkeyedValidPathInfo>::to_json(json, v);
+    json["path"] = v.path;
+}
+
 } // namespace nlohmann
diff --git a/src/libstore/realisation.cc b/src/libstore/realisation.cc
index a7f3b98d6..4aeb05874 100644
--- a/src/libstore/realisation.cc
+++ b/src/libstore/realisation.cc
@@ -144,6 +144,16 @@ namespace nlohmann {
 
 using namespace nix;
 
+DrvOutput adl_serializer<DrvOutput>::from_json(const json & json)
+{
+    return DrvOutput::parse(getString(json));
+}
+
+void adl_serializer<DrvOutput>::to_json(json & json, const DrvOutput & drvOutput)
+{
+    json = drvOutput.to_string();
+}
+
 UnkeyedRealisation adl_serializer<UnkeyedRealisation>::from_json(const json & json0)
 {
     auto json = getObject(json0);
@@ -182,14 +192,14 @@ Realisation adl_serializer<Realisation>::from_json(const json & json0)
 
     return Realisation{
         static_cast<UnkeyedRealisation>(json0),
-        DrvOutput::parse(valueAt(json, "id")),
+        valueAt(json, "id"),
     };
 }
 
 void adl_serializer<Realisation>::to_json(json & json, const Realisation & r)
 {
     json = static_cast<const UnkeyedRealisation &>(r);
-    json["id"] = r.id.to_string();
+    json["id"] = r.id;
 }
 
 } // namespace nlohmann
diff --git a/src/libutil-test-support/include/nix/util/tests/json-characterization.hh b/src/libutil-test-support/include/nix/util/tests/json-characterization.hh
index d713c615b..0ee6fd2fd 100644
--- a/src/libutil-test-support/include/nix/util/tests/json-characterization.hh
+++ b/src/libutil-test-support/include/nix/util/tests/json-characterization.hh
@@ -11,6 +11,34 @@
 
 namespace nix {
 
+/**
+ * Golden test for JSON reading
+ */
+template<typename T>
+void readJsonTest(CharacterizationTest & test, PathView testStem, const T & expected, auto... args)
+{
+    using namespace nlohmann;
+    test.readTest(Path{testStem} + ".json", [&](const auto & encodedRaw) {
+        auto encoded = json::parse(encodedRaw);
+        T decoded = adl_serializer<T>::from_json(encoded, args...);
+        ASSERT_EQ(decoded, expected);
+    });
+}
+
+/**
+ * Golden test for JSON writing
+ */
+template<typename T>
+void writeJsonTest(CharacterizationTest & test, PathView testStem, const T & value)
+{
+    using namespace nlohmann;
+    test.writeTest(
+        Path{testStem} + ".json",
+        [&]() -> json { return static_cast<json>(value); },
+        [](const auto & file) { return json::parse(readFile(file)); },
+        [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); });
+}
+
 /**
  * Mixin class for writing characterization tests for `nlohmann::json`
  * conversions for a given type.
@@ -26,12 +54,7 @@ struct JsonCharacterizationTest : virtual CharacterizationTest
      */
     void readJsonTest(PathView testStem, const T & expected, auto... args)
     {
-        using namespace nlohmann;
-        readTest(Path{testStem} + ".json", [&](const auto & encodedRaw) {
-            auto encoded = json::parse(encodedRaw);
-            T decoded = adl_serializer<T>::from_json(encoded, args...);
-            ASSERT_EQ(decoded, expected);
-        });
+        nix::readJsonTest(*this, testStem, expected, args...);
     }
 
     /**
@@ -42,12 +65,7 @@ struct JsonCharacterizationTest : virtual CharacterizationTest
      */
     void writeJsonTest(PathView testStem, const T & value)
     {
-        using namespace nlohmann;
-        writeTest(
-            Path{testStem} + ".json",
-            [&]() -> json { return static_cast<json>(value); },
-            [](const auto & file) { return json::parse(readFile(file)); },
-            [](const auto & file, const auto & got) { return writeFile(file, got.dump(2) + "\n"); });
+        nix::writeJsonTest(*this, testStem, value);
     }
 };