diff --git a/bench/baseline.json b/bench/baseline.json
index 813d4bf0118102f9d18518b6630618a27e55675a..6264ff9d028cd369c95c4e38912bc7152f1370e4 100644
--- a/bench/baseline.json
+++ b/bench/baseline.json
@@ -1,35 +1,56 @@
 {
-  "schema_message": "hello.Person",
-  "results": [
+  "schemas": [
     {
-      "size_label": "10B",
-      "size_bytes": 10,
-      "encode": {"alloc_kb_per_op_full": 0.367, "alloc_kb_per_op_runtime": 0.633},
-      "decode": {"alloc_kb_per_op_full": 0.508, "alloc_kb_per_op_runtime": 0.508}
-    },
-    {
-      "size_label": "100B",
-      "size_bytes": 94,
-      "encode": {"alloc_kb_per_op_full": 0.367, "alloc_kb_per_op_runtime": 0.633},
-      "decode": {"alloc_kb_per_op_full": 0.508, "alloc_kb_per_op_runtime": 0.508}
-    },
-    {
-      "size_label": "1KB",
-      "size_bytes": 930,
-      "encode": {"alloc_kb_per_op_full": 5.978, "alloc_kb_per_op_runtime": 7.040},
-      "decode": {"alloc_kb_per_op_full": 7.750, "alloc_kb_per_op_runtime": 7.883}
-    },
-    {
-      "size_label": "10KB",
-      "size_bytes": 9634,
-      "encode": {"alloc_kb_per_op_full": 47.489, "alloc_kb_per_op_runtime": 48.551},
-      "decode": {"alloc_kb_per_op_full": 59.500, "alloc_kb_per_op_runtime": 59.633}
+      "schema": "hello.Person",
+      "results": [
+        {
+          "size_label": "10B",
+          "size_bytes": 10,
+          "encode": {"alloc_kb_per_op_full": 0.133, "alloc_kb_per_op_runtime": 0.133},
+          "decode": {"alloc_kb_per_op_full": 0.109, "alloc_kb_per_op_runtime": 0.109}
+        },
+        {
+          "size_label": "100B",
+          "size_bytes": 94,
+          "encode": {"alloc_kb_per_op_full": 0.133, "alloc_kb_per_op_runtime": 0.133},
+          "decode": {"alloc_kb_per_op_full": 0.109, "alloc_kb_per_op_runtime": 0.109}
+        },
+        {
+          "size_label": "1KB",
+          "size_bytes": 930,
+          "encode": {"alloc_kb_per_op_full": 1.336, "alloc_kb_per_op_runtime": 1.336},
+          "decode": {"alloc_kb_per_op_full": 0.977, "alloc_kb_per_op_runtime": 0.977}
+        },
+        {
+          "size_label": "10KB",
+          "size_bytes": 9634,
+          "encode": {"alloc_kb_per_op_full": 8.340, "alloc_kb_per_op_runtime": 8.340},
+          "decode": {"alloc_kb_per_op_full": 4.727, "alloc_kb_per_op_runtime": 4.727}
+        },
+        {
+          "size_label": "100KB",
+          "size_bytes": 96674,
+          "encode": {"alloc_kb_per_op_full": 128.521, "alloc_kb_per_op_runtime": 128.521},
+          "decode": {"alloc_kb_per_op_full": 32.727, "alloc_kb_per_op_runtime": 32.727}
+        }
+      ]
     },
     {
-      "size_label": "100KB",
-      "size_bytes": 96674,
-      "encode": {"alloc_kb_per_op_full": 444.126, "alloc_kb_per_op_runtime": 445.189},
-      "decode": {"alloc_kb_per_op_full": 567.500, "alloc_kb_per_op_runtime": 567.633}
+      "schema": "proto2_basic.BenchPayload",
+      "results": [
+        {
+          "size_label": "min",
+          "size_bytes": 5,
+          "encode": {"alloc_kb_per_op_full": 0.102, "alloc_kb_per_op_runtime": 0.102},
+          "decode": {"alloc_kb_per_op_full": 0.359, "alloc_kb_per_op_runtime": 0.359}
+        },
+        {
+          "size_label": "mid",
+          "size_bytes": 609,
+          "encode": {"alloc_kb_per_op_full": 1.438, "alloc_kb_per_op_runtime": 1.438},
+          "decode": {"alloc_kb_per_op_full": 2.313, "alloc_kb_per_op_runtime": 2.313}
+        }
+      ]
     }
   ]
 }
diff --git a/bench/bench.lua b/bench/bench.lua
index 356b9c35370568c2e4fbadd048efd1fa2e75190c..bcb14e5927dc81efa66f81ba298a302b48d0ca6a 100644
--- a/bench/bench.lua
+++ b/bench/bench.lua
@@ -22,20 +22,30 @@ local json  = require('json')
 local fio   = require('fio')
 
 local MODES = {'full', 'runtime'}
-local SIZES = {
+
+-- Per-fixture size lists. The proto3 Person fixture sweeps five decades to
+-- characterize behavior across allocation regimes; proto2 only needs two
+-- sizes (one fits-in-cache, one larger) because its purpose is to gate
+-- the proto2-specific shapes (required/group/extension), not to recharacterize
+-- alloc scaling — that's already covered by Person.
+local PERSON_SIZES = {
     {label = '10B',   target = 10},
     {label = '100B',  target = 100},
     {label = '1KB',   target = 1024},
     {label = '10KB',  target = 10240},
     {label = '100KB', target = 102400},
 }
+local PROTO2_SIZES = {
+    {label = 'min',  target = 0},     -- minimal: required + extension only
+    {label = 'mid',  target = 1024},  -- with group + repeated + extension
+}
 
 -- Build a `Person` payload whose encoded size is close to `target` bytes.
 --
 -- Strategy: pick one knob per decade so each size still exercises the
 -- full encoder (varints, packed repeated, length-delimited strings,
 -- nested messages) — not just one giant byte-string.
-local function build_payload(target)
+local function build_person_payload(target)
     if target <= 10 then
         -- name(6) + age(1) ⇒ 10 bytes encoded.
         return {name = 'bigbes', age = 42}
@@ -65,6 +75,65 @@     end
     return p
 end
 
+-- Build a `BenchPayload` proto2 message. Two sizes:
+--   * `min` — required + one extension (~12 bytes): tightest measure of the
+--     per-message overhead the new code paths add.
+--   * `mid` — required + group + repeated + extension (~1 KB): exercises
+--     SGROUP/EGROUP framing, the packed-int32 path under proto2 semantics
+--     (NOT packed unless explicitly marked), the `pairs`-free
+--     extensions_list walk, and the nested message branch.
+local function build_proto2_payload(target)
+    if target <= 0 then
+        return {
+            id = 7,
+            _extensions = {
+                ['proto2_basic.ext_count'] = 42,
+            },
+        }
+    end
+    local n_tags    = 16
+    local per_tag   = 30
+    local tags      = {}
+    for i = 1, n_tags do
+        tags[i] = string.rep('t', per_tag - 2) .. string.format('%02d', i)
+    end
+    local lucky = {}
+    for i = 1, 8 do lucky[i] = 1000 + i end
+    return {
+        id            = 7,
+        name          = 'bench',
+        retries       = 9,
+        lucky_numbers = lucky,
+        tags          = tags,
+        inner         = {key = string.rep('k', 16), weight = 3},
+        stats         = {latency_ns = 1234567, attempts = 4},
+        _extensions = {
+            ['proto2_basic.ext_count'] = 99,
+            ['proto2_basic.ext_label'] = string.rep('x', 32),
+        },
+    }
+end
+
+-- Each fixture binds a schema + payload builder + sizes to bench.
+local FIXTURES = {
+    {
+        name = 'hello.Person',
+        module_path = '.hello.hello_pb',
+        encode_field = 'Person_encode',
+        decode_field = 'Person_decode',
+        build_payload = build_person_payload,
+        sizes = PERSON_SIZES,
+    },
+    {
+        name = 'proto2_basic.BenchPayload',
+        module_path = '.proto2_basic.proto2_basic_pb',
+        encode_field = 'BenchPayload_encode',
+        decode_field = 'BenchPayload_decode',
+        build_payload = build_proto2_payload,
+        sizes = PROTO2_SIZES,
+    },
+}
+
 -- Pick iteration count adaptively: smaller messages need more iters to
 -- amortize loop + clock overhead; larger messages need fewer to keep
 -- wall time bounded.
@@ -142,12 +211,12 @@         iters        = n,
     }
 end
 
-local function bench_one(mode, size)
-    local hello_pb = require(mode .. '.hello.hello_pb')
-    local encode   = hello_pb.Person_encode
-    local decode   = hello_pb.Person_decode
+local function bench_one(fixture, mode, size)
+    local mod    = require(mode .. fixture.module_path)
+    local encode = mod[fixture.encode_field]
+    local decode = mod[fixture.decode_field]
 
-    local payload = build_payload(size.target)
+    local payload = fixture.build_payload(size.target)
     local bytes   = encode(payload)
     local n       = iter_count(#bytes)
     local runs    = 5
@@ -168,6 +237,7 @@     dec_throughput.alloc_kb_per_op    = dec_alloc.kb_per_op
     dec_throughput.alloc_bytes_per_op = dec_alloc.bytes_per_op
 
     return {
+        schema     = fixture.name,
         mode       = mode,
         size_label = size.label,
         size_bytes = #bytes,
@@ -177,24 +247,28 @@     }
 end
 
 local function run_all()
-    local results = {}
-    for _, mode in ipairs(MODES) do
-        for _, size in ipairs(SIZES) do
-            io.stderr:write(string.format('  bench %s/%s ... ', mode, size.label))
-            io.stderr:flush()
-            local r = bench_one(mode, size)
-            io.stderr:write(string.format(
-                'enc %.0f msgs/s (%.1f MB/s)  dec %.0f msgs/s (%.1f MB/s)\n',
-                r.encode.msgs_per_s, r.encode.mb_per_s,
-                r.decode.msgs_per_s, r.decode.mb_per_s))
-            results[#results + 1] = r
+    local schemas = {}
+    for _, fixture in ipairs(FIXTURES) do
+        io.stderr:write(string.format('schema %s\n', fixture.name))
+        local results = {}
+        for _, mode in ipairs(MODES) do
+            for _, size in ipairs(fixture.sizes) do
+                io.stderr:write(string.format('  bench %s/%s ... ', mode, size.label))
+                io.stderr:flush()
+                local r = bench_one(fixture, mode, size)
+                io.stderr:write(string.format(
+                    'enc %.0f msgs/s (%.1f MB/s)  dec %.0f msgs/s (%.1f MB/s)\n',
+                    r.encode.msgs_per_s, r.encode.mb_per_s,
+                    r.decode.msgs_per_s, r.decode.mb_per_s))
+                results[#results + 1] = r
+            end
         end
+        schemas[#schemas + 1] = {schema = fixture.name, results = results}
     end
     return {
-        tarantool       = _TARANTOOL,
-        jit             = jit and jit.version or nil,
-        schema_message  = 'hello.Person',
-        results         = results,
+        tarantool = _TARANTOOL,
+        jit       = jit and jit.version or nil,
+        schemas   = schemas,
     }
 end
 
@@ -216,17 +290,24 @@     local lines = {}
     lines[#lines + 1] = '{'
     lines[#lines + 1] = string.format('  "tarantool": %s,', json.encode(doc.tarantool))
     lines[#lines + 1] = string.format('  "jit": %s,', json.encode(doc.jit or json.NULL))
-    lines[#lines + 1] = string.format('  "schema_message": %s,', json.encode(doc.schema_message))
-    lines[#lines + 1] = '  "results": ['
-    for i, r in ipairs(doc.results) do
-        local sep = (i == #doc.results) and '' or ','
+    lines[#lines + 1] = '  "schemas": ['
+    for si, schema in ipairs(doc.schemas) do
+        local schema_sep = (si == #doc.schemas) and '' or ','
         lines[#lines + 1] = '    {'
-        lines[#lines + 1] = string.format('      "mode": %s,', json.encode(r.mode))
-        lines[#lines + 1] = string.format('      "size_label": %s,', json.encode(r.size_label))
-        lines[#lines + 1] = string.format('      "size_bytes": %d,', r.size_bytes)
-        lines[#lines + 1] = string.format('      "encode": %s,', render_metric(r.encode))
-        lines[#lines + 1] = string.format('      "decode": %s', render_metric(r.decode))
-        lines[#lines + 1] = '    }' .. sep
+        lines[#lines + 1] = string.format('      "schema": %s,', json.encode(schema.schema))
+        lines[#lines + 1] = '      "results": ['
+        for i, r in ipairs(schema.results) do
+            local sep = (i == #schema.results) and '' or ','
+            lines[#lines + 1] = '        {'
+            lines[#lines + 1] = string.format('          "mode": %s,', json.encode(r.mode))
+            lines[#lines + 1] = string.format('          "size_label": %s,', json.encode(r.size_label))
+            lines[#lines + 1] = string.format('          "size_bytes": %d,', r.size_bytes)
+            lines[#lines + 1] = string.format('          "encode": %s,', render_metric(r.encode))
+            lines[#lines + 1] = string.format('          "decode": %s', render_metric(r.decode))
+            lines[#lines + 1] = '        }' .. sep
+        end
+        lines[#lines + 1] = '      ]'
+        lines[#lines + 1] = '    }' .. schema_sep
     end
     lines[#lines + 1] = '  ]'
     lines[#lines + 1] = '}'
@@ -239,50 +320,69 @@ -- reproducible to within ~10 bytes regardless of machine — it counts
 -- bytes, not time — so that's all we commit. Throughput is in --print
 -- output for human inspection only.
 local function reduce_for_baseline(doc)
-    local by_key = {}
-    for _, r in ipairs(doc.results) do
-        by_key[r.mode .. '/' .. r.size_label] = r
-    end
-    local out = {}
-    for _, size in ipairs(SIZES) do
-        local full    = by_key['full/'    .. size.label]
-        local runtime = by_key['runtime/' .. size.label]
-        out[#out + 1] = {
-            size_label = size.label,
-            size_bytes = full.size_bytes,
-            encode = {
-                alloc_kb_per_op_full    = full.encode.alloc_kb_per_op,
-                alloc_kb_per_op_runtime = runtime.encode.alloc_kb_per_op,
-            },
-            decode = {
-                alloc_kb_per_op_full    = full.decode.alloc_kb_per_op,
-                alloc_kb_per_op_runtime = runtime.decode.alloc_kb_per_op,
-            },
-        }
+    local out_schemas = {}
+    for _, schema in ipairs(doc.schemas) do
+        local by_key = {}
+        for _, r in ipairs(schema.results) do
+            by_key[r.mode .. '/' .. r.size_label] = r
+        end
+        -- Recover size order from the first mode's run (declaration order).
+        local seen, sizes = {}, {}
+        for _, r in ipairs(schema.results) do
+            if not seen[r.size_label] then
+                seen[r.size_label] = true
+                sizes[#sizes + 1] = r.size_label
+            end
+        end
+        local results = {}
+        for _, label in ipairs(sizes) do
+            local full    = by_key['full/'    .. label]
+            local runtime = by_key['runtime/' .. label]
+            results[#results + 1] = {
+                size_label = label,
+                size_bytes = full.size_bytes,
+                encode = {
+                    alloc_kb_per_op_full    = full.encode.alloc_kb_per_op,
+                    alloc_kb_per_op_runtime = runtime.encode.alloc_kb_per_op,
+                },
+                decode = {
+                    alloc_kb_per_op_full    = full.decode.alloc_kb_per_op,
+                    alloc_kb_per_op_runtime = runtime.decode.alloc_kb_per_op,
+                },
+            }
+        end
+        out_schemas[#out_schemas + 1] = {schema = schema.schema, results = results}
     end
-    return {schema_message = doc.schema_message, results = out}
+    return {schemas = out_schemas}
 end
 
 local function render_baseline(reduced)
     local lines = {'{'}
-    lines[#lines + 1] = string.format('  "schema_message": %s,', json.encode(reduced.schema_message))
-    lines[#lines + 1] = '  "results": ['
-    for i, r in ipairs(reduced.results) do
-        local sep = (i == #reduced.results) and '' or ','
+    lines[#lines + 1] = '  "schemas": ['
+    for si, schema in ipairs(reduced.schemas) do
+        local schema_sep = (si == #reduced.schemas) and '' or ','
         lines[#lines + 1] = '    {'
-        lines[#lines + 1] = string.format('      "size_label": %s,', json.encode(r.size_label))
-        lines[#lines + 1] = string.format('      "size_bytes": %d,', r.size_bytes)
-        lines[#lines + 1] = string.format(
-            '      "encode": {"alloc_kb_per_op_full": %.3f, '
-            .. '"alloc_kb_per_op_runtime": %.3f},',
-            r.encode.alloc_kb_per_op_full,
-            r.encode.alloc_kb_per_op_runtime)
-        lines[#lines + 1] = string.format(
-            '      "decode": {"alloc_kb_per_op_full": %.3f, '
-            .. '"alloc_kb_per_op_runtime": %.3f}',
-            r.decode.alloc_kb_per_op_full,
-            r.decode.alloc_kb_per_op_runtime)
-        lines[#lines + 1] = '    }' .. sep
+        lines[#lines + 1] = string.format('      "schema": %s,', json.encode(schema.schema))
+        lines[#lines + 1] = '      "results": ['
+        for i, r in ipairs(schema.results) do
+            local sep = (i == #schema.results) and '' or ','
+            lines[#lines + 1] = '        {'
+            lines[#lines + 1] = string.format('          "size_label": %s,', json.encode(r.size_label))
+            lines[#lines + 1] = string.format('          "size_bytes": %d,', r.size_bytes)
+            lines[#lines + 1] = string.format(
+                '          "encode": {"alloc_kb_per_op_full": %.3f, '
+                .. '"alloc_kb_per_op_runtime": %.3f},',
+                r.encode.alloc_kb_per_op_full,
+                r.encode.alloc_kb_per_op_runtime)
+            lines[#lines + 1] = string.format(
+                '          "decode": {"alloc_kb_per_op_full": %.3f, '
+                .. '"alloc_kb_per_op_runtime": %.3f}',
+                r.decode.alloc_kb_per_op_full,
+                r.decode.alloc_kb_per_op_runtime)
+            lines[#lines + 1] = '        }' .. sep
+        end
+        lines[#lines + 1] = '      ]'
+        lines[#lines + 1] = '    }' .. schema_sep
     end
     lines[#lines + 1] = '  ]'
     lines[#lines + 1] = '}'
@@ -299,27 +399,36 @@ -- ratios swing 30%+ run-to-run on a busy laptop — useless as a gate.
 local function compare(current, baseline, tolerance)
     local function index(b)
         local m = {}
-        for _, r in ipairs(b.results) do m[r.size_label] = r end
+        for _, schema in ipairs(b.schemas or {}) do
+            for _, r in ipairs(schema.results) do
+                m[schema.schema .. '|' .. r.size_label] = r
+            end
+        end
         return m
     end
-    local cur = index(current)
+    local cur  = index(current)
     local base = index(baseline)
     local regressions = {}
-    for _, size in ipairs(SIZES) do
-        local c = cur[size.label]
-        local b = base[size.label]
-        if not c or not b then goto continue end
-        for _, op in ipairs({'encode', 'decode'}) do
-            for _, key in ipairs({'alloc_kb_per_op_full', 'alloc_kb_per_op_runtime'}) do
-                local bv, cv = b[op][key], c[op][key]
-                if bv > 0 and cv > bv * (1 + tolerance) then
-                    regressions[#regressions + 1] = string.format(
-                        '%s/%s %s: %.3f -> %.3f KB/op (+%.1f%%)',
-                        size.label, op, key, bv, cv, (cv / bv - 1) * 100)
+    -- Walk in baseline declaration order so the report is stable.
+    for _, schema in ipairs(baseline.schemas or {}) do
+        for _, r in ipairs(schema.results) do
+            local key = schema.schema .. '|' .. r.size_label
+            local c = cur[key]
+            local b = base[key]
+            if c and b then
+                for _, op in ipairs({'encode', 'decode'}) do
+                    for _, ak in ipairs({'alloc_kb_per_op_full', 'alloc_kb_per_op_runtime'}) do
+                        local bv, cv = b[op][ak], c[op][ak]
+                        if bv > 0 and cv > bv * (1 + tolerance) then
+                            regressions[#regressions + 1] = string.format(
+                                '%s %s/%s %s: %.3f -> %.3f KB/op (+%.1f%%)',
+                                schema.schema, r.size_label, op, ak,
+                                bv, cv, (cv / bv - 1) * 100)
+                        end
+                    end
                 end
             end
         end
-        ::continue::
     end
     return regressions
 end
diff --git a/bench/jit_trace.lua b/bench/jit_trace.lua
index 68b6ef38eac033a4975ea95c5761e87cf66dea8e..ce852452b7ac9ba2a14a58cdaba45e65f020f10b 100644
--- a/bench/jit_trace.lua
+++ b/bench/jit_trace.lua
@@ -269,6 +269,76 @@     check(mode .. '/Person_decode multi-byte varint',
         function() hello.Person_decode(big_person_bytes) end)
 end
 
+-- ---------------------------------------------------------------------------
+-- Proto2-specific shapes: required, groups, extensions, closed enums.
+--
+-- The new code paths share most of their machinery with proto3 message and
+-- scalar fields, but introduce three distinct shapes worth pinning:
+--
+--   1. The `required` writer wraps the regular scalar writer with a missing-
+--      value error. Should stay JIT-stable when the value is set.
+--   2. Group fields use SGROUP/EGROUP tags and a per-element body without a
+--      length prefix. Different wire shape than messages; new writer/reader.
+--   3. Extensions are walked at encode time via a `pairs()` over an array
+--      view (`extensions_list`), and looked up at decode time via the
+--      `extensions_by_id` hash. Both sides need to stay on trace; the
+--      hash lookup is one cdata read so should be fine, but the encode
+--      walk would abort if we used `pairs()` over a non-array — see the
+--      list-view layer in pb.codec.
+-- ---------------------------------------------------------------------------
+
+for _, mode in ipairs({'full', 'runtime'}) do
+    local p2 = require(mode .. '.proto2_basic.proto2_basic_pb')
+
+    -- Required: encode emits a clear error on missing, but the happy path
+    -- where the value is set should compile and stay on trace.
+    local card = {r = 7}
+    local card_bytes = p2.Cardinality_encode(card)
+    check(mode .. '/Cardinality_encode (required)',
+        function() p2.Cardinality_encode(card) end)
+    check(mode .. '/Cardinality_decode (required)',
+        function() p2.Cardinality_decode(card_bytes) end)
+
+    -- Groups: SGROUP/EGROUP framed body, no length prefix. Singular path.
+    local with_group = {singlegroup = {a = 7, s = 'ok'}}
+    local with_group_bytes = p2.WithGroup_encode(with_group)
+    check(mode .. '/WithGroup_encode (group)',
+        function() p2.WithGroup_encode(with_group) end)
+    check(mode .. '/WithGroup_decode (group)',
+        function() p2.WithGroup_decode(with_group_bytes) end)
+
+    -- Repeated groups: same shape, exercises the per-element bracket loop.
+    local with_rep = {repgroup = {{n = 1}, {n = 2}, {n = 3}, {n = 4}}}
+    local with_rep_bytes = p2.WithGroup_encode(with_rep)
+    check(mode .. '/WithGroup_encode (repeated group)',
+        function() p2.WithGroup_encode(with_rep) end)
+    check(mode .. '/WithGroup_decode (repeated group)',
+        function() p2.WithGroup_decode(with_rep_bytes) end)
+end
+
+-- Extensions: register a small proto2 fixture inline so the trace gate
+-- doesn't depend on the bulky conformance schema. Exercises both encode
+-- (walks _extensions and routes through encode_field) and decode (routes
+-- an unknown tag through extensions_by_id → decode_extension).
+do
+    local p2tests = require('full.protobuf_test_messages.proto2.test_messages_proto2_pb')
+    local Foo     = p2tests.TestAllTypesProto2_descriptor
+    local msg = {
+        _extensions = {
+            ['protobuf_test_messages.proto2.extension_int32']  = 42,
+            ['protobuf_test_messages.proto2.extension_string'] = 'hi',
+        },
+    }
+    -- Encode-prime via the descriptor-driven path; tracing the inline
+    -- emitted code wouldn't cover the extension loop (it's in codec.lua).
+    local pb = require('pb')
+    local ext_bytes = pb.encode(Foo, msg)
+    check('full/extension_encode',
+        function() pb.encode(Foo, msg) end)
+    check('full/extension_decode',
+        function() pb.decode(Foo, ext_bytes) end)
+end
+
 -- Pin the known map limitation: pairs() over a hash compiles to bytecode
 -- ISNEXT, which Tarantool LuaJIT 2.1 can't trace. If this stops triggering,
 -- upstream lifted the restriction and our scope claim can broaden.
diff --git a/cmd/protoc-gen-tarantool/internal/gen/inline.go b/cmd/protoc-gen-tarantool/internal/gen/inline.go
index 9b5e06aa8e75a59b855077cf39ef77df4fd49eb0..8854a1c73d3e333ad56ea11d790c4375e5e9913b 100644
--- a/cmd/protoc-gen-tarantool/internal/gen/inline.go
+++ b/cmd/protoc-gen-tarantool/internal/gen/inline.go
@@ -53,6 +53,31 @@
 	for _, f := range m.Fields {
 		emitInlineEncodeField(w, f, file, selfPath, imports, prefix)
 	}
+	// Proto2 extensions: delegate to pb.codec.encode_field once per set
+	// entry. We don't inline an extension-specific writer here because
+	// extensions are runtime-mutable — a user can register more after the
+	// module loads — so the canonical iteration source is the descriptor's
+	// extensions_list. The walk is JIT-stable (array, not pairs over a
+	// hash). Skip entirely when extensions_list is nil (most proto3 messages
+	// and proto2 messages without `extensions` ranges) so the hot path
+	// pays nothing.
+	w.line("    local _exts = t._extensions")
+	w.line("    if _exts ~= nil then")
+	w.line("        local _elist = M.%s_descriptor.extensions_list", name)
+	w.line("        if _elist ~= nil then")
+	w.line("            for _i = 1, #_elist do")
+	w.line("                local _ext = _elist[_i]")
+	w.line("                local _ev = _exts[_ext.full_name]")
+	w.line("                if _ev ~= nil then")
+	w.line("                    pb.codec.encode_field(_ext, _ev, out, true)")
+	w.line("                end")
+	w.line("            end")
+	// encode_field uses out[#out + 1] = … and doesn't know about our
+	// local `n` cursor — resync so the unknown-fields append below lands
+	// after the extension bytes, not on top of them.
+	w.line("            n = #out")
+	w.line("        end")
+	w.line("    end")
 	// Preserve unknown fields captured at decode time.
 	w.line("    local _uf = t._unknown_fields")
 	w.line("    if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end")
@@ -342,9 +367,20 @@ 		// No fields — every wire byte is unknown.
 		w.line("        if true then")
 	}
 	w.line("        else")
-	w.line("            pos = wire.skip_field(buf, pos, wt, id)")
-	w.line("            if _uf == nil then _uf = {} end")
-	w.line("            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)")
+	// Proto2 extensions: an unknown tag may belong to a registered
+	// extension on this descriptor. Route through pb.codec's
+	// decode_extension which mirrors the in-line dispatch on field
+	// kind (scalar/enum/message/group, singular/repeated) and stores
+	// into result._extensions[full_name].
+	w.line("            local _ebid = M.%s_descriptor.extensions_by_id", name)
+	w.line("            local _ext = _ebid and _ebid[id] or nil")
+	w.line("            if _ext ~= nil then")
+	w.line("                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)")
+	w.line("            else")
+	w.line("                pos = wire.skip_field(buf, pos, wt, id)")
+	w.line("                if _uf == nil then _uf = {} end")
+	w.line("                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)")
+	w.line("            end")
 	w.line("        end")
 	w.line("    end")
 	w.line("    if _uf ~= nil then result._unknown_fields = table.concat(_uf) end")
diff --git a/examples/expected/full/conformance/conformance_pb.lua b/examples/expected/full/conformance/conformance_pb.lua
index df624215fd601f547f653e0435f3f7b7adbbc865..82619429a10c814b58a8c0b9eb7146af1d3d224a 100644
--- a/examples/expected/full/conformance/conformance_pb.lua
+++ b/examples/expected/full/conformance/conformance_pb.lua
@@ -225,6 +225,20 @@         n = n + 1; out[n] = "\x1a"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestStatus_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -256,9 +270,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.matched_name = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestStatus_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -296,6 +316,20 @@             n = n + 1; out[n] = wire.encode_varint(#_b)
             n = n + 1; out[n] = _b
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.FailureSet_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -321,9 +355,15 @@             local payload
             payload, pos = wire.decode_len(buf, pos)
             list[#list + 1] = M.TestStatus_decode(payload)
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.FailureSet_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -430,6 +470,20 @@     if v ~= nil and v ~= false then
         n = n + 1; out[n] = "\x48"
         n = n + 1; out[n] = wire.encode_bool(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.ConformanceRequest_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -502,9 +556,15 @@             local val
             val, pos = wire.decode_bool(buf, pos)
             result.print_unknown_fields = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.ConformanceRequest_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -604,6 +664,20 @@         n = n + 1; out[n] = "\x42"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.ConformanceResponse_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -731,9 +805,15 @@             result.json_payload = nil
             result.skipped = nil
             result.jspb_payload = nil
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.ConformanceResponse_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -766,6 +846,20 @@     if v ~= nil and v ~= false then
         n = n + 1; out[n] = "\x08"
         n = n + 1; out[n] = wire.encode_bool(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.JspbEncodingConfig_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -789,9 +883,15 @@             local val
             val, pos = wire.decode_bool(buf, pos)
             result.use_jspb_array_any_format = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.JspbEncodingConfig_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
diff --git a/examples/expected/full/hello/hello_pb.lua b/examples/expected/full/hello/hello_pb.lua
index f59d634c0a297d42a60f327baf877f09eb615ec4..88cac7b9e0c63e8c0dbf08eaf83dc172bc12b152 100644
--- a/examples/expected/full/hello/hello_pb.lua
+++ b/examples/expected/full/hello/hello_pb.lua
@@ -246,6 +246,20 @@         n = n + 1; out[n] = "\x22"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Result_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -292,9 +306,15 @@             end
             result.text = nil
             result.code = nil
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Result_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -328,6 +348,20 @@         n = n + 1; out[n] = "\x0a"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.HelloRequest_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -351,9 +385,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.name = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.HelloRequest_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -387,6 +427,20 @@         n = n + 1; out[n] = "\x0a"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.HelloReply_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -410,9 +464,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.greeting = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.HelloReply_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -534,6 +594,20 @@         n = n + 1; out[n] = "\x62"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Event_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -601,9 +675,15 @@             local payload
             payload, pos = wire.decode_len(buf, pos)
             result.update_mask = pb.wkt.FieldMask_decode(payload)
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Event_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -657,6 +737,20 @@         n = n + 1; out[n] = "\x22"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Address_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -692,9 +786,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.apartment = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Address_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -873,6 +973,20 @@             n = n + 1; out[n] = _tag
             n = n + 1; out[n] = wire.encode_len(table.concat(entry))
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Person_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -1017,9 +1131,15 @@                 end
             end
             map[_key] = _val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Person_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
diff --git a/examples/expected/full/proto2_basic/proto2_basic_pb.lua b/examples/expected/full/proto2_basic/proto2_basic_pb.lua
index 185b7ef43c6d4740f4dffef1d5826355491a6b86..5fff79a93056ba600eab3777bd427e728a96a010 100644
--- a/examples/expected/full/proto2_basic/proto2_basic_pb.lua
+++ b/examples/expected/full/proto2_basic/proto2_basic_pb.lua
@@ -27,6 +27,9 @@ M.Nested_Inner_descriptor = {name = "proto2_basic.Nested.Inner"}
 M.WithGroup_descriptor = {name = "proto2_basic.WithGroup"}
 M.WithGroup_SingleGroup_descriptor = {name = "proto2_basic.WithGroup.SingleGroup"}
 M.WithGroup_RepGroup_descriptor = {name = "proto2_basic.WithGroup.RepGroup"}
+M.BenchPayload_descriptor = {name = "proto2_basic.BenchPayload"}
+M.BenchPayload_Stats_descriptor = {name = "proto2_basic.BenchPayload.Stats"}
+M.BenchPayload_Inner_descriptor = {name = "proto2_basic.BenchPayload.Inner"}
 
 -- Message: proto2_basic.Defaults
 M.Defaults_descriptor.fields = {
@@ -121,6 +124,49 @@ M.WithGroup_RepGroup_fields = pb.field_names({
     n = "n",
 })
 
+-- Message: proto2_basic.BenchPayload
+M.BenchPayload_descriptor.fields = {
+    {name="id", id=1, kind='scalar', proto_type="int32", required=true},
+    {name="name", id=2, kind='scalar', proto_type="string", optional=true, default_value="anonymous"},
+    {name="retries", id=3, kind='scalar', proto_type="int32", optional=true, default_value=3},
+    {name="lucky_numbers", id=4, kind='scalar', proto_type="int32", repeated=true, packed=true, options={packed = true}},
+    {name="tags", id=5, kind='scalar', proto_type="string", repeated=true},
+    {name="inner", id=6, kind='message', message=M.BenchPayload_Inner_descriptor, optional=true},
+    {name="stats", id=7, kind='group', message=M.BenchPayload_Stats_descriptor, optional=true},
+}
+pb.finalize_message(M.BenchPayload_descriptor)
+M.BenchPayload_fields = pb.field_names({
+    id = "id",
+    name = "name",
+    retries = "retries",
+    lucky_numbers = "lucky_numbers",
+    tags = "tags",
+    inner = "inner",
+    stats = "stats",
+})
+
+-- Message: proto2_basic.BenchPayload.Stats
+M.BenchPayload_Stats_descriptor.fields = {
+    {name="latency_ns", id=8, kind='scalar', proto_type="int32", optional=true},
+    {name="attempts", id=9, kind='scalar', proto_type="int32", optional=true},
+}
+pb.finalize_message(M.BenchPayload_Stats_descriptor)
+M.BenchPayload_Stats_fields = pb.field_names({
+    latency_ns = "latency_ns",
+    attempts = "attempts",
+})
+
+-- Message: proto2_basic.BenchPayload.Inner
+M.BenchPayload_Inner_descriptor.fields = {
+    {name="key", id=1, kind='scalar', proto_type="string", required=true},
+    {name="weight", id=2, kind='scalar', proto_type="int32", optional=true},
+}
+pb.finalize_message(M.BenchPayload_Inner_descriptor)
+M.BenchPayload_Inner_fields = pb.field_names({
+    key = "key",
+    weight = "weight",
+})
+
 -- EmmyLua / lua-language-server type annotations.
 -- These are comments — no runtime effect. They give editors
 -- autocomplete and type-checking for the generated wrappers.
@@ -164,6 +210,26 @@
 ---@class proto2_basic.WithGroup.RepGroup
 ---@field n? integer
 
+--- Bench fixture exercising the proto2-only shapes: required scalar,
+--- optional repeated, custom default, a `group` field, and a nested
+--- message. Used by bench/bench.lua against both modes.
+---@class proto2_basic.BenchPayload
+---@field id integer
+---@field name? string
+---@field retries? integer
+---@field lucky_numbers integer[]
+---@field tags string[]
+---@field inner? proto2_basic.BenchPayload.Inner
+---@field stats? proto2_basic.BenchPayload.Stats
+
+---@class proto2_basic.BenchPayload.Stats
+---@field latency_ns? integer
+---@field attempts? integer
+
+---@class proto2_basic.BenchPayload.Inner
+---@field key string
+---@field weight? integer
+
 ---@param t? proto2_basic.Defaults
 ---@return proto2_basic.Defaults
 function M.Defaults_new(t) return t or {} end
@@ -237,6 +303,20 @@         end
         n = n + 1; out[n] = "\x48"
         n = n + 1; out[n] = wire.encode_int32(nv)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Defaults_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -292,9 +372,15 @@             local u
             u, pos = wire.decode_varint(buf, pos)
             result.color = wire.varint_to_int32(u)
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Defaults_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -409,6 +495,20 @@             n = n + 1; out[n] = _tag
             n = n + 1; out[n] = wire.encode_int32(v[_i])
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Cardinality_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -487,9 +587,15 @@                 val, pos = wire.decode_int32(buf, pos)
                 list[#list + 1] = val
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Cardinality_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -538,6 +644,20 @@         n = n + 1; out[n] = "\x12"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Nested_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -575,9 +695,15 @@             else
                 pb.codec.merge_message(M.Nested_Inner_descriptor, prev, M.Nested_Inner_decode(payload))
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Nested_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -616,6 +742,20 @@         error("required field missing on encode: proto2_basic.Nested.Inner.x", 0)
     end
     n = n + 1; out[n] = "\x08"
     n = n + 1; out[n] = wire.encode_int32(v)
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.Nested_Inner_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -639,9 +779,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.x = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.Nested_Inner_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -686,6 +832,20 @@             n = n + 1; out[n] = M.WithGroup_RepGroup_encode(v[_i])
             n = n + 1; out[n] = _etag
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.WithGroup_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -720,9 +880,15 @@             local payload
             payload, pos = pb.codec.decode_group(M.WithGroup_RepGroup_descriptor, buf, pos, 4)
             list[#list + 1] = payload
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.WithGroup_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -767,6 +933,20 @@         n = n + 1; out[n] = "\x1a"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.WithGroup_SingleGroup_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -794,9 +974,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.s = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.WithGroup_SingleGroup_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -839,6 +1025,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\x28"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.WithGroup_RepGroup_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -862,9 +1062,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.n = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.WithGroup_RepGroup_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -883,5 +1089,402 @@ ---@return boolean
 function M.WithGroup_RepGroup_has_n(t) return t.n ~= nil end
 ---@param t proto2_basic.WithGroup.RepGroup
 function M.WithGroup_RepGroup_clear_n(t) t.n = nil end
+
+---@param t? proto2_basic.BenchPayload
+---@return proto2_basic.BenchPayload
+function M.BenchPayload_new(t) return t or {} end
+
+---@param t proto2_basic.BenchPayload
+---@return string
+function M.BenchPayload_encode(t)
+    if type(t) ~= 'table' then
+        error("expected table for proto2_basic.BenchPayload, got " .. type(t), 0)
+    end
+    local out, n = {}, 0
+    local v
+    -- field 1: id
+    v = t.id
+    if v == nil then
+        error("required field missing on encode: proto2_basic.BenchPayload.id", 0)
+    end
+    n = n + 1; out[n] = "\x08"
+    n = n + 1; out[n] = wire.encode_int32(v)
+    -- field 2: name
+    v = t.name
+    if v ~= nil then
+        n = n + 1; out[n] = "\x12"
+        n = n + 1; out[n] = wire.encode_varint(#v)
+        n = n + 1; out[n] = v
+    end
+    -- field 3: retries
+    v = t.retries
+    if v ~= nil then
+        n = n + 1; out[n] = "\x18"
+        n = n + 1; out[n] = wire.encode_int32(v)
+    end
+    -- field 4: lucky_numbers
+    v = t.lucky_numbers
+    if v ~= nil and #v > 0 then
+        local parts, m = {}, 0
+        for _i = 1, #v do
+            m = m + 1; parts[m] = wire.encode_int32(v[_i])
+        end
+        local _b = table.concat(parts)
+        n = n + 1; out[n] = "\x22"
+        n = n + 1; out[n] = wire.encode_varint(#_b)
+        n = n + 1; out[n] = _b
+    end
+    -- field 5: tags
+    v = t.tags
+    if v ~= nil and #v > 0 then
+        local _tag = "\x2a"
+        for _i = 1, #v do
+            local _b = v[_i]
+            n = n + 1; out[n] = _tag
+            n = n + 1; out[n] = wire.encode_varint(#_b)
+            n = n + 1; out[n] = _b
+        end
+    end
+    -- field 6: inner
+    v = t.inner
+    if v ~= nil or type(v) == 'cdata' then
+        local _b = M.BenchPayload_Inner_encode(v)
+        n = n + 1; out[n] = "\x32"
+        n = n + 1; out[n] = wire.encode_varint(#_b)
+        n = n + 1; out[n] = _b
+    end
+    -- field 7: stats
+    v = t.stats
+    if v ~= nil or type(v) == 'cdata' then
+        n = n + 1; out[n] = "\x3b"
+        n = n + 1; out[n] = M.BenchPayload_Stats_encode(v)
+        n = n + 1; out[n] = "\x3c"
+    end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.BenchPayload_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
+    local _uf = t._unknown_fields
+    if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
+    return table.concat(out)
+end
+
+---@param b string
+---@return proto2_basic.BenchPayload
+function M.BenchPayload_decode(buf)
+    if type(buf) ~= 'string' then
+        error("expected string for proto2_basic.BenchPayload decode, got " .. type(buf), 0)
+    end
+    local result = {}
+    local pos, len = 1, #buf
+    local _uf
+    while pos <= len do
+        local _tag_start = pos
+        local id, wt
+        id, wt, pos = wire.decode_tag(buf, pos)
+        if id == 1 then
+            local val
+            val, pos = wire.decode_int32(buf, pos)
+            result.id = val
+        elseif id == 2 then
+            local val
+            val, pos = wire.decode_string(buf, pos)
+            result.name = val
+        elseif id == 3 then
+            local val
+            val, pos = wire.decode_int32(buf, pos)
+            result.retries = val
+        elseif id == 4 then
+            local list = result.lucky_numbers
+            if list == nil then list = {}; result.lucky_numbers = list end
+            if wt == 2 then
+                local payload
+                payload, pos = wire.decode_len(buf, pos)
+                local p2, lim = 1, #payload
+                while p2 <= lim do
+                    local val
+                    val, p2 = wire.decode_int32(payload, p2)
+                    list[#list + 1] = val
+                end
+            else
+                local val
+                val, pos = wire.decode_int32(buf, pos)
+                list[#list + 1] = val
+            end
+        elseif id == 5 then
+            local list = result.tags
+            if list == nil then list = {}; result.tags = list end
+            local val
+            val, pos = wire.decode_string(buf, pos)
+            list[#list + 1] = val
+        elseif id == 6 then
+            local payload
+            payload, pos = wire.decode_len(buf, pos)
+            local prev = result.inner
+            if prev == nil then
+                result.inner = M.BenchPayload_Inner_decode(payload)
+            else
+                pb.codec.merge_message(M.BenchPayload_Inner_descriptor, prev, M.BenchPayload_Inner_decode(payload))
+            end
+        elseif id == 7 then
+            local payload
+            payload, pos = pb.codec.decode_group(M.BenchPayload_Stats_descriptor, buf, pos, 7)
+            local prev = result.stats
+            if prev == nil then
+                result.stats = payload
+            else
+                pb.codec.merge_message(M.BenchPayload_Stats_descriptor, prev, payload)
+            end
+        else
+            local _ebid = M.BenchPayload_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
+        end
+    end
+    if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
+    return result
+end
+
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_descriptor, b) end
+---@param t proto2_basic.BenchPayload
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_text(t, opts) return pb.text.encode(M.BenchPayload_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_name(t) return t.name ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_name(t) t.name = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_retries(t) return t.retries ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_retries(t) t.retries = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_inner(t) return t.inner ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_inner(t) t.inner = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_stats(t) return t.stats ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_stats(t) t.stats = nil end
+
+---@param t? proto2_basic.BenchPayload.Stats
+---@return proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_new(t) return t or {} end
+
+---@param t proto2_basic.BenchPayload.Stats
+---@return string
+function M.BenchPayload_Stats_encode(t)
+    if type(t) ~= 'table' then
+        error("expected table for proto2_basic.BenchPayload.Stats, got " .. type(t), 0)
+    end
+    local out, n = {}, 0
+    local v
+    -- field 8: latency_ns
+    v = t.latency_ns
+    if v ~= nil then
+        n = n + 1; out[n] = "\x40"
+        n = n + 1; out[n] = wire.encode_int32(v)
+    end
+    -- field 9: attempts
+    v = t.attempts
+    if v ~= nil then
+        n = n + 1; out[n] = "\x48"
+        n = n + 1; out[n] = wire.encode_int32(v)
+    end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.BenchPayload_Stats_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
+    local _uf = t._unknown_fields
+    if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
+    return table.concat(out)
+end
+
+---@param b string
+---@return proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_decode(buf)
+    if type(buf) ~= 'string' then
+        error("expected string for proto2_basic.BenchPayload.Stats decode, got " .. type(buf), 0)
+    end
+    local result = {}
+    local pos, len = 1, #buf
+    local _uf
+    while pos <= len do
+        local _tag_start = pos
+        local id, wt
+        id, wt, pos = wire.decode_tag(buf, pos)
+        if id == 8 then
+            local val
+            val, pos = wire.decode_int32(buf, pos)
+            result.latency_ns = val
+        elseif id == 9 then
+            local val
+            val, pos = wire.decode_int32(buf, pos)
+            result.attempts = val
+        else
+            local _ebid = M.BenchPayload_Stats_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
+        end
+    end
+    if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
+    return result
+end
+
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_Stats_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_Stats_descriptor, b) end
+---@param t proto2_basic.BenchPayload.Stats
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_Stats_text(t, opts) return pb.text.encode(M.BenchPayload_Stats_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload.Stats
+---@return boolean
+function M.BenchPayload_Stats_has_latency_ns(t) return t.latency_ns ~= nil end
+---@param t proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_clear_latency_ns(t) t.latency_ns = nil end
+---@param t proto2_basic.BenchPayload.Stats
+---@return boolean
+function M.BenchPayload_Stats_has_attempts(t) return t.attempts ~= nil end
+---@param t proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_clear_attempts(t) t.attempts = nil end
+
+---@param t? proto2_basic.BenchPayload.Inner
+---@return proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_new(t) return t or {} end
+
+---@param t proto2_basic.BenchPayload.Inner
+---@return string
+function M.BenchPayload_Inner_encode(t)
+    if type(t) ~= 'table' then
+        error("expected table for proto2_basic.BenchPayload.Inner, got " .. type(t), 0)
+    end
+    local out, n = {}, 0
+    local v
+    -- field 1: key
+    v = t.key
+    if v == nil then
+        error("required field missing on encode: proto2_basic.BenchPayload.Inner.key", 0)
+    end
+    n = n + 1; out[n] = "\x0a"
+    n = n + 1; out[n] = wire.encode_varint(#v)
+    n = n + 1; out[n] = v
+    -- field 2: weight
+    v = t.weight
+    if v ~= nil then
+        n = n + 1; out[n] = "\x10"
+        n = n + 1; out[n] = wire.encode_int32(v)
+    end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.BenchPayload_Inner_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
+    local _uf = t._unknown_fields
+    if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
+    return table.concat(out)
+end
+
+---@param b string
+---@return proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_decode(buf)
+    if type(buf) ~= 'string' then
+        error("expected string for proto2_basic.BenchPayload.Inner decode, got " .. type(buf), 0)
+    end
+    local result = {}
+    local pos, len = 1, #buf
+    local _uf
+    while pos <= len do
+        local _tag_start = pos
+        local id, wt
+        id, wt, pos = wire.decode_tag(buf, pos)
+        if id == 1 then
+            local val
+            val, pos = wire.decode_string(buf, pos)
+            result.key = val
+        elseif id == 2 then
+            local val
+            val, pos = wire.decode_int32(buf, pos)
+            result.weight = val
+        else
+            local _ebid = M.BenchPayload_Inner_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
+        end
+    end
+    if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
+    return result
+end
+
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_Inner_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_Inner_descriptor, b) end
+---@param t proto2_basic.BenchPayload.Inner
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_Inner_text(t, opts) return pb.text.encode(M.BenchPayload_Inner_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload.Inner
+---@return boolean
+function M.BenchPayload_Inner_has_weight(t) return t.weight ~= nil end
+---@param t proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_clear_weight(t) t.weight = nil end
+
+-- Extension: proto2_basic.ext_count extends proto2_basic.BenchPayload (tag 100)
+pb.register_extension(M.BenchPayload_descriptor, {name="ext_count", full_name="proto2_basic.ext_count", id=100, kind='scalar', proto_type="int32", optional=true})
+-- Extension: proto2_basic.ext_label extends proto2_basic.BenchPayload (tag 101)
+pb.register_extension(M.BenchPayload_descriptor, {name="ext_label", full_name="proto2_basic.ext_label", id=101, kind='scalar', proto_type="string", optional=true})
 
 return M
diff --git a/examples/expected/full/protobuf_test_messages/proto2/test_messages_proto2_pb.lua b/examples/expected/full/protobuf_test_messages/proto2/test_messages_proto2_pb.lua
index ce7617bd1d56ce71e063c7f63d8cfeba249a87d8..f84ac372610e9b6078a4879370370feda640b25b 100644
--- a/examples/expected/full/protobuf_test_messages/proto2/test_messages_proto2_pb.lua
+++ b/examples/expected/full/protobuf_test_messages/proto2/test_messages_proto2_pb.lua
@@ -2259,6 +2259,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\x90\x1a"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -3835,9 +3849,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.Field_name18__ = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4163,6 +4183,20 @@         n = n + 1; out[n] = "\x12"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto2_NestedMessage_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4195,9 +4229,15 @@             else
                 pb.codec.merge_message(M.TestAllTypesProto2_descriptor, prev, M.TestAllTypesProto2_decode(payload))
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto2_NestedMessage_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4246,6 +4286,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\xd8\x0c"
         n = n + 1; out[n] = wire.encode_uint32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto2_Data_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4273,9 +4327,15 @@             local val
             val, pos = wire.decode_uint32(buf, pos)
             result.group_uint32 = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto2_Data_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4324,6 +4384,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\xf0\x0c"
         n = n + 1; out[n] = wire.encode_uint32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto2_MultiWordGroupField_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4351,9 +4425,15 @@             local val
             val, pos = wire.decode_uint32(buf, pos)
             result.group_uint32 = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto2_MultiWordGroupField_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4396,6 +4476,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\x08"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.ForeignMessageProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4419,9 +4513,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.c = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.ForeignMessageProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4464,6 +4564,20 @@     v = t.group_uint32
     if v ~= nil then
         n = n + 1; out[n] = "\xd8\x07"
         n = n + 1; out[n] = wire.encode_uint32(v)
+    end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.GroupField_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
     end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
@@ -4492,9 +4606,15 @@             local val
             val, pos = wire.decode_uint32(buf, pos)
             result.group_uint32 = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.GroupField_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4574,6 +4694,20 @@             n = n + 1; out[n] = _tag
             n = n + 1; out[n] = wire.encode_int32(v[_i])
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.UnknownToTestAllTypes_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4640,9 +4774,15 @@                 val, pos = wire.decode_int32(buf, pos)
                 list[#list + 1] = val
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.UnknownToTestAllTypes_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4700,6 +4840,20 @@     if v ~= nil then
         n = n + 1; out[n] = "\x08"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.UnknownToTestAllTypes_OptionalGroup_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4723,9 +4877,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.a = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.UnknownToTestAllTypes_OptionalGroup_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4757,6 +4917,20 @@         error("expected table for protobuf_test_messages.proto2.NullHypothesisProto2, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.NullHypothesisProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4777,9 +4951,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.NullHypothesisProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4806,6 +4986,20 @@         error("expected table for protobuf_test_messages.proto2.EnumOnlyProto2, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.EnumOnlyProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4826,9 +5020,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.EnumOnlyProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4862,6 +5062,20 @@         n = n + 1; out[n] = "\x0a"
         n = n + 1; out[n] = wire.encode_varint(#v)
         n = n + 1; out[n] = v
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.OneStringProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4885,9 +5099,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             result.data = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.OneStringProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4943,6 +5163,20 @@             n = n + 1; out[n] = wire.encode_varint(#_b)
             n = n + 1; out[n] = _b
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.ProtoWithKeywords_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4976,9 +5210,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             list[#list + 1] = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.ProtoWithKeywords_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5317,6 +5557,20 @@     end
     n = n + 1; out[n] = "\xfa\x0f"
     n = n + 1; out[n] = wire.encode_varint(#v)
     n = n + 1; out[n] = v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllRequiredTypesProto2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5517,9 +5771,15 @@             local val
             val, pos = wire.decode_bytes(buf, pos)
             result.default_bytes = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllRequiredTypesProto2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5575,6 +5835,20 @@         n = n + 1; out[n] = "\x1a"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllRequiredTypesProto2_NestedMessage_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5616,9 +5890,15 @@             else
                 pb.codec.merge_message(M.TestAllRequiredTypesProto2_descriptor, prev, M.TestAllRequiredTypesProto2_decode(payload))
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllRequiredTypesProto2_NestedMessage_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5664,6 +5944,20 @@         error("required field missing on encode: protobuf_test_messages.proto2.TestAllRequiredTypesProto2.Data.group_uint32", 0)
     end
     n = n + 1; out[n] = "\xd8\x0c"
     n = n + 1; out[n] = wire.encode_uint32(v)
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllRequiredTypesProto2_Data_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5691,9 +5985,15 @@             local val
             val, pos = wire.decode_uint32(buf, pos)
             result.group_uint32 = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllRequiredTypesProto2_Data_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5766,6 +6066,20 @@         n = n + 1; out[n] = "\x2a"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5850,9 +6164,15 @@             result.a2 = nil
             result.a3 = nil
             result.a4 = nil
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5879,6 +6199,20 @@         error("expected table for protobuf_test_messages.proto2.TestLargeOneof.A1, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_A1_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5899,9 +6233,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_A1_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5928,6 +6268,20 @@         error("expected table for protobuf_test_messages.proto2.TestLargeOneof.A2, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_A2_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5948,9 +6302,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_A2_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -5977,6 +6337,20 @@         error("expected table for protobuf_test_messages.proto2.TestLargeOneof.A3, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_A3_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -5997,9 +6371,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_A3_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -6026,6 +6406,20 @@         error("expected table for protobuf_test_messages.proto2.TestLargeOneof.A4, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_A4_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -6046,9 +6440,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_A4_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -6075,6 +6475,20 @@         error("expected table for protobuf_test_messages.proto2.TestLargeOneof.A5, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestLargeOneof_A5_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -6095,9 +6509,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestLargeOneof_A5_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
diff --git a/examples/expected/full/protobuf_test_messages/proto3/test_messages_proto3_pb.lua b/examples/expected/full/protobuf_test_messages/proto3/test_messages_proto3_pb.lua
index 68f67851f7c6a8e03938f3590e6dd5b96d20e3e8..8f3ad036c5cb3ba7454883e6269efc637a4a032b 100644
--- a/examples/expected/full/protobuf_test_messages/proto3/test_messages_proto3_pb.lua
+++ b/examples/expected/full/protobuf_test_messages/proto3/test_messages_proto3_pb.lua
@@ -2207,6 +2207,20 @@     if v ~= nil and v ~= 0 then
         n = n + 1; out[n] = "\x90\x1a"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto3_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -3861,9 +3875,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.Field_name18__ = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto3_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -3904,6 +3924,20 @@         n = n + 1; out[n] = "\x12"
         n = n + 1; out[n] = wire.encode_varint(#_b)
         n = n + 1; out[n] = _b
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.TestAllTypesProto3_NestedMessage_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -3936,9 +3970,15 @@             else
                 pb.codec.merge_message(M.TestAllTypesProto3_descriptor, prev, M.TestAllTypesProto3_decode(payload))
             end
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.TestAllTypesProto3_NestedMessage_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -3971,6 +4011,20 @@     if v ~= nil and v ~= 0 then
         n = n + 1; out[n] = "\x08"
         n = n + 1; out[n] = wire.encode_int32(v)
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.ForeignMessage_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -3994,9 +4048,15 @@             local val
             val, pos = wire.decode_int32(buf, pos)
             result.c = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.ForeignMessage_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4023,6 +4083,20 @@         error("expected table for protobuf_test_messages.proto3.NullHypothesisProto3, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.NullHypothesisProto3_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4043,9 +4117,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.NullHypothesisProto3_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
@@ -4072,6 +4152,20 @@         error("expected table for protobuf_test_messages.proto3.EnumOnlyProto3, got " .. type(t), 0)
     end
     local out, n = {}, 0
     local v
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.EnumOnlyProto3_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -4092,9 +4186,15 @@         local id, wt
         id, wt, pos = wire.decode_tag(buf, pos)
         if true then
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.EnumOnlyProto3_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
diff --git a/examples/expected/full/quickstart/quickstart_pb.lua b/examples/expected/full/quickstart/quickstart_pb.lua
index 742d565bf46a3b940ba02fca2dfa4810df92f0de..8df8c9a674b22328cc9efa8205e5b342e1cff152 100644
--- a/examples/expected/full/quickstart/quickstart_pb.lua
+++ b/examples/expected/full/quickstart/quickstart_pb.lua
@@ -96,6 +96,20 @@             n = n + 1; out[n] = wire.encode_varint(#_b)
             n = n + 1; out[n] = _b
         end
     end
+    local _exts = t._extensions
+    if _exts ~= nil then
+        local _elist = M.User_descriptor.extensions_list
+        if _elist ~= nil then
+            for _i = 1, #_elist do
+                local _ext = _elist[_i]
+                local _ev = _exts[_ext.full_name]
+                if _ev ~= nil then
+                    pb.codec.encode_field(_ext, _ev, out, true)
+                end
+            end
+            n = #out
+        end
+    end
     local _uf = t._unknown_fields
     if _uf ~= nil and _uf ~= '' then n = n + 1; out[n] = _uf end
     return table.concat(out)
@@ -133,9 +147,15 @@             local val
             val, pos = wire.decode_string(buf, pos)
             list[#list + 1] = val
         else
-            pos = wire.skip_field(buf, pos, wt, id)
-            if _uf == nil then _uf = {} end
-            _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            local _ebid = M.User_descriptor.extensions_by_id
+            local _ext = _ebid and _ebid[id] or nil
+            if _ext ~= nil then
+                pos = pb.codec.decode_extension(_ext, buf, pos, wt, result)
+            else
+                pos = wire.skip_field(buf, pos, wt, id)
+                if _uf == nil then _uf = {} end
+                _uf[#_uf + 1] = buf:sub(_tag_start, pos - 1)
+            end
         end
     end
     if _uf ~= nil then result._unknown_fields = table.concat(_uf) end
diff --git a/examples/expected/runtime/proto2_basic/proto2_basic_pb.lua b/examples/expected/runtime/proto2_basic/proto2_basic_pb.lua
index d8b7fc0565daaa148fc119b8dcaff622cae5f02b..46b43130c9cd99a63a03a7af17e04bfd2f46de08 100644
--- a/examples/expected/runtime/proto2_basic/proto2_basic_pb.lua
+++ b/examples/expected/runtime/proto2_basic/proto2_basic_pb.lua
@@ -27,6 +27,9 @@ M.Nested_Inner_descriptor = {name = "proto2_basic.Nested.Inner"}
 M.WithGroup_descriptor = {name = "proto2_basic.WithGroup"}
 M.WithGroup_SingleGroup_descriptor = {name = "proto2_basic.WithGroup.SingleGroup"}
 M.WithGroup_RepGroup_descriptor = {name = "proto2_basic.WithGroup.RepGroup"}
+M.BenchPayload_descriptor = {name = "proto2_basic.BenchPayload"}
+M.BenchPayload_Stats_descriptor = {name = "proto2_basic.BenchPayload.Stats"}
+M.BenchPayload_Inner_descriptor = {name = "proto2_basic.BenchPayload.Inner"}
 
 -- Message: proto2_basic.Defaults
 M.Defaults_descriptor.fields = {
@@ -121,6 +124,49 @@ M.WithGroup_RepGroup_fields = pb.field_names({
     n = "n",
 })
 
+-- Message: proto2_basic.BenchPayload
+M.BenchPayload_descriptor.fields = {
+    {name="id", id=1, kind='scalar', proto_type="int32", required=true},
+    {name="name", id=2, kind='scalar', proto_type="string", optional=true, default_value="anonymous"},
+    {name="retries", id=3, kind='scalar', proto_type="int32", optional=true, default_value=3},
+    {name="lucky_numbers", id=4, kind='scalar', proto_type="int32", repeated=true, packed=true, options={packed = true}},
+    {name="tags", id=5, kind='scalar', proto_type="string", repeated=true},
+    {name="inner", id=6, kind='message', message=M.BenchPayload_Inner_descriptor, optional=true},
+    {name="stats", id=7, kind='group', message=M.BenchPayload_Stats_descriptor, optional=true},
+}
+pb.finalize_message(M.BenchPayload_descriptor)
+M.BenchPayload_fields = pb.field_names({
+    id = "id",
+    name = "name",
+    retries = "retries",
+    lucky_numbers = "lucky_numbers",
+    tags = "tags",
+    inner = "inner",
+    stats = "stats",
+})
+
+-- Message: proto2_basic.BenchPayload.Stats
+M.BenchPayload_Stats_descriptor.fields = {
+    {name="latency_ns", id=8, kind='scalar', proto_type="int32", optional=true},
+    {name="attempts", id=9, kind='scalar', proto_type="int32", optional=true},
+}
+pb.finalize_message(M.BenchPayload_Stats_descriptor)
+M.BenchPayload_Stats_fields = pb.field_names({
+    latency_ns = "latency_ns",
+    attempts = "attempts",
+})
+
+-- Message: proto2_basic.BenchPayload.Inner
+M.BenchPayload_Inner_descriptor.fields = {
+    {name="key", id=1, kind='scalar', proto_type="string", required=true},
+    {name="weight", id=2, kind='scalar', proto_type="int32", optional=true},
+}
+pb.finalize_message(M.BenchPayload_Inner_descriptor)
+M.BenchPayload_Inner_fields = pb.field_names({
+    key = "key",
+    weight = "weight",
+})
+
 -- EmmyLua / lua-language-server type annotations.
 -- These are comments — no runtime effect. They give editors
 -- autocomplete and type-checking for the generated wrappers.
@@ -163,6 +209,26 @@ ---@field s? string
 
 ---@class proto2_basic.WithGroup.RepGroup
 ---@field n? integer
+
+--- Bench fixture exercising the proto2-only shapes: required scalar,
+--- optional repeated, custom default, a `group` field, and a nested
+--- message. Used by bench/bench.lua against both modes.
+---@class proto2_basic.BenchPayload
+---@field id integer
+---@field name? string
+---@field retries? integer
+---@field lucky_numbers integer[]
+---@field tags string[]
+---@field inner? proto2_basic.BenchPayload.Inner
+---@field stats? proto2_basic.BenchPayload.Stats
+
+---@class proto2_basic.BenchPayload.Stats
+---@field latency_ns? integer
+---@field attempts? integer
+
+---@class proto2_basic.BenchPayload.Inner
+---@field key string
+---@field weight? integer
 
 ---@param t? proto2_basic.Defaults
 ---@return proto2_basic.Defaults
@@ -357,5 +423,96 @@ ---@return boolean
 function M.WithGroup_RepGroup_has_n(t) return t.n ~= nil end
 ---@param t proto2_basic.WithGroup.RepGroup
 function M.WithGroup_RepGroup_clear_n(t) t.n = nil end
+
+---@param t? proto2_basic.BenchPayload
+---@return proto2_basic.BenchPayload
+function M.BenchPayload_new(t) return t or {} end
+---@param t proto2_basic.BenchPayload
+---@return string
+function M.BenchPayload_encode(t) return pb.encode(M.BenchPayload_descriptor, t) end
+---@param b string
+---@return proto2_basic.BenchPayload
+function M.BenchPayload_decode(b) return pb.decode(M.BenchPayload_descriptor, b) end
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_descriptor, b) end
+---@param t proto2_basic.BenchPayload
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_text(t, opts) return pb.text.encode(M.BenchPayload_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_name(t) return t.name ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_name(t) t.name = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_retries(t) return t.retries ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_retries(t) t.retries = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_inner(t) return t.inner ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_inner(t) t.inner = nil end
+---@param t proto2_basic.BenchPayload
+---@return boolean
+function M.BenchPayload_has_stats(t) return t.stats ~= nil end
+---@param t proto2_basic.BenchPayload
+function M.BenchPayload_clear_stats(t) t.stats = nil end
+
+---@param t? proto2_basic.BenchPayload.Stats
+---@return proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_new(t) return t or {} end
+---@param t proto2_basic.BenchPayload.Stats
+---@return string
+function M.BenchPayload_Stats_encode(t) return pb.encode(M.BenchPayload_Stats_descriptor, t) end
+---@param b string
+---@return proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_decode(b) return pb.decode(M.BenchPayload_Stats_descriptor, b) end
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_Stats_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_Stats_descriptor, b) end
+---@param t proto2_basic.BenchPayload.Stats
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_Stats_text(t, opts) return pb.text.encode(M.BenchPayload_Stats_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload.Stats
+---@return boolean
+function M.BenchPayload_Stats_has_latency_ns(t) return t.latency_ns ~= nil end
+---@param t proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_clear_latency_ns(t) t.latency_ns = nil end
+---@param t proto2_basic.BenchPayload.Stats
+---@return boolean
+function M.BenchPayload_Stats_has_attempts(t) return t.attempts ~= nil end
+---@param t proto2_basic.BenchPayload.Stats
+function M.BenchPayload_Stats_clear_attempts(t) t.attempts = nil end
+
+---@param t? proto2_basic.BenchPayload.Inner
+---@return proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_new(t) return t or {} end
+---@param t proto2_basic.BenchPayload.Inner
+---@return string
+function M.BenchPayload_Inner_encode(t) return pb.encode(M.BenchPayload_Inner_descriptor, t) end
+---@param b string
+---@return proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_decode(b) return pb.decode(M.BenchPayload_Inner_descriptor, b) end
+---@param b string
+---@return pb.MessageView
+function M.BenchPayload_Inner_decode_lazy(b) return pb.decode_lazy(M.BenchPayload_Inner_descriptor, b) end
+---@param t proto2_basic.BenchPayload.Inner
+---@param opts? {single_line: boolean?, indent: string?}
+---@return string
+function M.BenchPayload_Inner_text(t, opts) return pb.text.encode(M.BenchPayload_Inner_descriptor, t, opts) end
+---@param t proto2_basic.BenchPayload.Inner
+---@return boolean
+function M.BenchPayload_Inner_has_weight(t) return t.weight ~= nil end
+---@param t proto2_basic.BenchPayload.Inner
+function M.BenchPayload_Inner_clear_weight(t) t.weight = nil end
+
+-- Extension: proto2_basic.ext_count extends proto2_basic.BenchPayload (tag 100)
+pb.register_extension(M.BenchPayload_descriptor, {name="ext_count", full_name="proto2_basic.ext_count", id=100, kind='scalar', proto_type="int32", optional=true})
+-- Extension: proto2_basic.ext_label extends proto2_basic.BenchPayload (tag 101)
+pb.register_extension(M.BenchPayload_descriptor, {name="ext_label", full_name="proto2_basic.ext_label", id=101, kind='scalar', proto_type="string", optional=true})
 
 return M
diff --git a/runtime/pb/codec.lua b/runtime/pb/codec.lua
index b46fb400b0f4670053f459f3517d3f12007ea26f..6724e6c2564b72ca010310049813492720b6f805 100644
--- a/runtime/pb/codec.lua
+++ b/runtime/pb/codec.lua
@@ -909,15 +909,21 @@             encode_field(f, data[f.name], out, f.optional)
         end
     end
     -- Proto2 extensions: data._extensions = { [full_name] = value, ... }.
-    -- Walk known extensions in declaration order via extensions_by_full_name
-    -- so the wire bytes are stable across runs (pairs() ordering otherwise
-    -- depends on hash). Unknown extensions stay in _unknown_fields.
+    -- Walk via the parallel array `extensions_list` rather than `pairs()`
+    -- over a hash — pairs() compiles to bytecode ISNEXT, which is NYI in
+    -- Tarantool's LuaJIT 2.1 fork (same limitation that gates map encode).
+    -- pb.register_extension keeps the array in registration order, which
+    -- is also the deterministic on-wire order.
     local exts = data._extensions
-    if exts ~= nil and desc.extensions_by_full_name ~= nil then
-        for full_name, ext in pairs(desc.extensions_by_full_name) do
-            local v = exts[full_name]
-            if v ~= nil then
-                encode_field(ext, v, out, true)
+    if exts ~= nil then
+        local elist = desc.extensions_list
+        if elist ~= nil then
+            for i = 1, #elist do
+                local ext = elist[i]
+                local v = exts[ext.full_name]
+                if v ~= nil then
+                    encode_field(ext, v, out, true)
+                end
             end
         end
     end
@@ -1037,7 +1043,13 @@ -- decode_extension routes wire bytes for a registered proto2 extension into
 -- result._extensions[ext.full_name]. Mirrors the in-line decode dispatch on
 -- field kind (scalar/enum/message/group, singular/repeated). Returns the
 -- new buffer position after the value bytes.
-local function decode_extension(ext, buf, pos, wt, result)
+-- Exposed for inline-mode generated code: the per-message decoder calls
+-- decode_extension when it sees an unknown tag that matches a registered
+-- extension on the descriptor.
+local decode_extension
+function M.decode_extension(...) return decode_extension(...) end
+
+decode_extension = function(ext, buf, pos, wt, result)
     local exts = result._extensions
     if exts == nil then exts = {}; result._extensions = exts end
     local key = ext.full_name
diff --git a/runtime/pb/init.lua b/runtime/pb/init.lua
index 71c1e068b6b744dadcdc17419d8b821899e90926..14bb3b722751eab8919fac95455fc0de49c2b4f5 100644
--- a/runtime/pb/init.lua
+++ b/runtime/pb/init.lua
@@ -190,14 +190,23 @@
     -- Proto2 extension registration. Generated code emits one call per
     -- `extend Foo { ... }` field, attaching the extension's field shape
     -- to the extendee's descriptor. The codec consults `extensions_by_id`
-    -- when decoding an unrecognized tag and walks `extensions_by_full_name`
-    -- when encoding `data._extensions`.
+    -- when decoding an unrecognized tag, walks `extensions_list` (array)
+    -- when encoding `data._extensions`, and uses
+    -- `extensions_by_full_name` for text/JSON encoder lookups.
+    --
+    -- `extensions_list` is the JIT-stable iteration source — pairs() over
+    -- a hash compiles to bytecode ISNEXT which is NYI in LuaJIT 2.1, so
+    -- the hot encode loop iterates the array instead. The hash tables
+    -- stay around for O(1) name/id lookups.
     register_extension = function(extendee_desc, ext)
         if extendee_desc.extensions_by_id == nil then
             extendee_desc.extensions_by_id = {}
             extendee_desc.extensions_by_full_name = {}
+            extendee_desc.extensions_list = {}
         end
         extendee_desc.extensions_by_id[ext.id] = ext
         extendee_desc.extensions_by_full_name[ext.full_name] = ext
+        local list = extendee_desc.extensions_list
+        list[#list + 1] = ext
     end,
 }
diff --git a/runtime/pb/json.lua b/runtime/pb/json.lua
index b1c9851319ab1e9a9c205aac9ed4ede0b30ecc2e..57975ff7dd38f02809cdffbe0d6b67bebd233196 100644
--- a/runtime/pb/json.lua
+++ b/runtime/pb/json.lua
@@ -940,17 +940,21 @@             end
         end
     end
     -- Proto2 extensions: surface set entries under their bracketed
-    -- fully-qualified name (`[pkg.ext_name]`). Repeated extensions
-    -- emit as JSON arrays per the proto2 JSON spec.
+    -- fully-qualified name (`[pkg.ext_name]`). Walk the array
+    -- (`extensions_list`) rather than the hash — pairs() compiles to
+    -- ISNEXT which is NYI on the JIT. Repeated extensions emit as JSON
+    -- arrays per the proto2 JSON spec.
     local exts = t._extensions
-    if exts ~= nil and desc.extensions_by_full_name ~= nil then
-        for full_name, ext in pairs(desc.extensions_by_full_name) do
-            local v = exts[full_name]
+    local elist = exts ~= nil and desc.extensions_list or nil
+    if elist ~= nil then
+        for i = 1, #elist do
+            local ext = elist[i]
+            local v = exts[ext.full_name]
             if v ~= nil then
-                local k = '[' .. full_name .. ']'
+                local k = '[' .. ext.full_name .. ']'
                 if ext.repeated then
                     local arr = setmetatable({}, {__serialize='seq'})
-                    for i = 1, #v do arr[i] = encode_field_value(ext, v[i]) end
+                    for j = 1, #v do arr[j] = encode_field_value(ext, v[j]) end
                     out[k] = arr
                 else
                     out[k] = encode_field_value(ext, v)
diff --git a/runtime/pb/text.lua b/runtime/pb/text.lua
index d940150eb7585e6d4a8271021d8b9260f9165f36..b8055e6c79c857e282c4efdbbaf4bba7ebef9394 100644
--- a/runtime/pb/text.lua
+++ b/runtime/pb/text.lua
@@ -370,19 +370,23 @@             emit_field(buf, f, v, depth)
         end
     end
     -- Proto2 extensions: emit each set entry as `[full.name]: value` in
-    -- declaration order via the registry. Repeated extensions emit one
-    -- entry per element to keep the round-trip lossless.
+    -- registration order via the array view (`extensions_list`). Same
+    -- ISNEXT-NYI reasoning as the wire encoder — walk the array, not the
+    -- hash. Repeated extensions emit one entry per element to keep the
+    -- round-trip lossless.
     local exts = t._extensions
-    if exts ~= nil and desc.extensions_by_full_name ~= nil then
-        for full_name, ext in pairs(desc.extensions_by_full_name) do
-            local v = exts[full_name]
+    local elist = exts ~= nil and desc.extensions_list or nil
+    if elist ~= nil then
+        for i = 1, #elist do
+            local ext = elist[i]
+            local v = exts[ext.full_name]
             if v ~= nil then
                 if ext.repeated then
-                    for i = 1, #v do
-                        emit_extension_entry(buf, ext, full_name, v[i], depth)
+                    for j = 1, #v do
+                        emit_extension_entry(buf, ext, ext.full_name, v[j], depth)
                     end
                 else
-                    emit_extension_entry(buf, ext, full_name, v, depth)
+                    emit_extension_entry(buf, ext, ext.full_name, v, depth)
                 end
             end
         end
diff --git a/test/proto/proto2_basic.proto b/test/proto/proto2_basic.proto
index 98f2b6ff7b0f632ba29468db8b969d549ce8e172..6a588b069bb0d498b4733e2856057dbb2851eb30 100644
--- a/test/proto/proto2_basic.proto
+++ b/test/proto/proto2_basic.proto
@@ -48,3 +48,32 @@   repeated group RepGroup = 4 {
     optional int32 n = 5;
   }
 }
+
+// Bench fixture exercising the proto2-only shapes: required scalar,
+// optional repeated, custom default, a `group` field, and a nested
+// message. Used by bench/bench.lua against both modes.
+message BenchPayload {
+  required int32 id            = 1;
+  optional string name         = 2 [default = "anonymous"];
+  optional int32 retries       = 3 [default = 3];
+  repeated int32 lucky_numbers = 4 [packed = true];
+  repeated string tags         = 5;
+  optional Inner inner         = 6;
+  optional group Stats = 7 {
+    optional int32 latency_ns = 8;
+    optional int32 attempts   = 9;
+  }
+
+  message Inner {
+    required string key = 1;
+    optional int32 weight = 2;
+  }
+
+  // Reserve a range for the file-level extensions declared below.
+  extensions 100 to 199;
+}
+
+extend BenchPayload {
+  optional int32  ext_count   = 100;
+  optional string ext_label   = 101;
+}
diff --git a/test/proto2_test.lua b/test/proto2_test.lua
index c1f0a9158add19606445deda9e9eafdf54286a0a..73de9044d885ba020cb8df19281846b28dac5f8f 100644
--- a/test/proto2_test.lua
+++ b/test/proto2_test.lua
@@ -188,6 +188,52 @@         local s = pb.WithGroup_text({singlegroup = {a = 7}})
         t.assert(s:find('SingleGroup'), 'expected SingleGroup label in: ' .. s)
         t.assert_not(s:find('singlegroup'), 'lowercase field name must not appear')
     end
+
+    -- ----- Proto2 extensions -----
+
+    g.test_extension_registry_uses_array_view = function()
+        -- The hot encode loop iterates extensions_list (array) rather than
+        -- pairs() over extensions_by_full_name to stay JIT-stable. If a
+        -- future refactor drops the array view, encode silently falls off
+        -- the JIT — pin both indices here.
+        local d = pb.BenchPayload_descriptor
+        t.assert(type(d.extensions_list) == 'table',
+            'extensions_list array view must exist')
+        t.assert(#d.extensions_list >= 2)
+        t.assert(d.extensions_by_id[100])
+        t.assert(d.extensions_by_full_name['proto2_basic.ext_count'])
+    end
+
+    g.test_extension_round_trip = function()
+        local msg = {
+            id = 7,
+            _extensions = {
+                ['proto2_basic.ext_count'] = 42,
+                ['proto2_basic.ext_label'] = 'tag',
+            },
+        }
+        local dec = pb.BenchPayload_decode(pb.BenchPayload_encode(msg))
+        t.assert_equals(dec.id, 7)
+        t.assert_equals(dec._extensions['proto2_basic.ext_count'], 42)
+        t.assert_equals(dec._extensions['proto2_basic.ext_label'], 'tag')
+    end
+
+    g.test_extension_inline_codegen_walks_them = function()
+        -- Regression pin: the inline (full-mode) generated code added an
+        -- explicit extensions walk after the field loop. Verify that the
+        -- bytes-on-wire match what the runtime codec produces for the
+        -- same input.
+        local full    = require('full.proto2_basic.proto2_basic_pb')
+        local runtime = require('runtime.proto2_basic.proto2_basic_pb')
+        local msg = {
+            id = 9,
+            _extensions = {['proto2_basic.ext_count'] = 17},
+        }
+        t.assert_equals(
+            hex(full.BenchPayload_encode(msg)),
+            hex(runtime.BenchPayload_encode(msg)),
+            'inline and runtime extension emission must match byte-for-byte')
+    end
 end
 
 -- Dynamic (source-parsed) proto2: load test/proto/proto2_basic.proto at