diff --git a/.github/scripts/codegen-check.sh b/.github/scripts/codegen-check.sh
new file mode 100644
index 0000000..3f27ae3
--- /dev/null
+++ b/.github/scripts/codegen-check.sh
@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+#
+# CI artifact — not part of the SDK.
+#
+# Renders the .trix/client-lib codegen plugin against the shared transfer
+# fixture and verifies the result the way a consumer would: the rendered module
+# is imported in a fresh venv with the dependencies its generated
+# requirements.txt pins installed — no editable install of the SDK source tree.
+#
+# Requires `tx3c` and `python` on PATH.
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+gen="$(mktemp -d)"
+trap 'rm -rf "$gen"' EXIT
+
+tx3c codegen \
+  --tii "$repo_root/sdk/tests/fixtures/transfer.tii" \
+  --template "$repo_root/.trix/client-lib" \
+  --output "$gen"
+
+for f in __init__.py requirements.txt; do
+  test -f "$gen/$f" || { echo "missing generated file: $f"; exit 1; }
+done
+
+for sym in \
+  'TARGET_TII_VERSION' \
+  'PROFILES' \
+  'TRANSFER_TIR' \
+  'class TransferParams' \
+  'class Client'; do
+  grep -qF "$sym" "$gen/__init__.py" || { echo "generated __init__.py missing: $sym"; exit 1; }
+done
+
+# Import the rendered module in a fresh venv with the dependencies its generated
+# requirements.txt pins, exactly as an end user would consume it.
+python -m venv "$gen/venv"
+"$gen/venv/bin/pip" install --quiet --upgrade pip
+"$gen/venv/bin/pip" install --quiet -r "$gen/requirements.txt"
+"$gen/venv/bin/python" -c "
+import importlib.util, sys
+spec = importlib.util.spec_from_file_location('tx3_generated_protocol', '$gen/__init__.py')
+module = importlib.util.module_from_spec(spec)
+sys.modules[spec.name] = module
+spec.loader.exec_module(module)
+assert module.TARGET_TII_VERSION == 'v1beta0', module.TARGET_TII_VERSION
+assert set(module.PROFILES) == {'local', 'preprod'}, module.PROFILES
+assert module.TRANSFER_TIR.version == 'v1beta0'
+assert module.TransferParams(quantity=1).quantity == 1
+print('generated module imported OK')
+"
+
+echo "codegen check passed"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bcb1475..83e2165 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,6 +36,27 @@ jobs:
         working-directory: ./sdk
         run: pytest tests -m "not e2e"
 
+  codegen:
+    name: codegen
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+          cache: pip
+          cache-dependency-path: sdk/pyproject.toml
+
+      - name: Setup tx3 toolchain
+        uses: tx3-lang/actions/setup@v1
+
+      - name: Render and verify codegen plugin
+        run: bash .github/scripts/codegen-check.sh
+
   e2e:
     name: e2e
     runs-on: ubuntu-latest
diff --git a/.trix/client-lib/__init__.py.hbs b/.trix/client-lib/__init__.py.hbs
index 1097127..8ea89a6 100644
--- a/.trix/client-lib/__init__.py.hbs
+++ b/.trix/client-lib/__init__.py.hbs
@@ -1,55 +1,88 @@
-# This file is auto-generated.
+# This file is auto-generated by trix codegen.
+# Target TII version: {{tii.tii.version}}
 
+from __future__ import annotations
+
+import json
 from dataclasses import dataclass
-from typing import Dict, Any
-from tx3_sdk.trp import Client as TRPClient, TxEnvelope, SubmitResponse, SubmitParams
+from typing import Any
 
-DEFAULT_TRP_ENDPOINT = "{{trpEndpoint}}"
+from tx3_sdk.core.bytes import TirEnvelope
+from tx3_sdk.trp.client import TrpClient
+from tx3_sdk.trp.spec import ResolveParams, SubmitParams, SubmitResponse, TxEnvelope
 
-DEFAULT_HEADERS = {
-{{#each headers}}
-    "{{@key}}": "{{this}}",
-{{/each}}
-}
+PROTOCOL_NAME = "{{tii.protocol.name}}"
+PROTOCOL_VERSION = "{{tii.protocol.version}}"
+TARGET_TII_VERSION = "{{tii.tii.version}}"
 
-DEFAULT_ENV_ARGS = {
-{{#each envArgs}}
-    "{{@key}}": "{{this}}",
-{{/each}}
-}
+{{#if tii.environment}}
+# JSON Schema of the protocol environment, embedded verbatim from the TII.
+ENVIRONMENT_SCHEMA: dict[str, Any] = json.loads(
+    """{{{json tii.environment}}}"""
+)
 
-{{#each transactions}}
+{{/if}}
+# Profiles embedded from the TII, keyed by name. Each value carries that
+# profile's `environment` values and `parties` addresses.
+PROFILES: dict[str, dict[str, Any]] = json.loads(
+    """{{{json tii.profiles}}}"""
+)
+
+{{#each tii.transactions}}
 @dataclass
-class {{pascalCase params_name}}:
-{{#each parameters}}
-    {{snakeCase name}}: {{typeFor type_name "python"}} # {{type_name}}
+class {{pascalCase @key}}Params:
+    """Arguments for the {{@key}} transaction."""
+
+{{#each params.properties}}
+    {{snakeCase @key}}: {{schemaTypeFor this "python"}}
 {{/each}}
 
-{{constantCase constant_name}} = {
-    "content": "{{ir_bytes}}",
-    "encoding": "hex",
-    "version": "{{ir_version}}",
-}
+
+{{constantCase @key}}_TIR = TirEnvelope(
+    content="{{tir.content}}",
+    encoding="{{tir.encoding}}",
+    version="{{tir.version}}",
+)
 
 {{/each}}
 class Client:
-    def __init__(self, options: Dict[str, Any]):
-        self._client = TRPClient(options)
-{{#each transactions}}
-
-    async def {{snakeCase function_name}}(self, args: {{pascalCase params_name}}) -> TxEnvelope:
-        return await self._client.resolve({
-            "tir": {{constantCase constant_name}},
-            "args": vars(args),
-        })
+    """Thin protocol facade over the TRP client."""
+
+    def __init__(
+        self,
+        endpoint: str,
+        headers: dict[str, str] | None = None,
+        profile: str | None = None,
+    ) -> None:
+        self._trp = TrpClient(endpoint=endpoint, headers=headers)
+        self._environment: dict[str, Any] | None = None
+        self._parties: dict[str, str] = {}
+        if profile is not None:
+            if profile not in PROFILES:
+                raise ValueError(f"unknown profile {profile!r}")
+            selected = PROFILES[profile]
+            self._environment = selected.get("environment") or None
+            self._parties = selected.get("parties") or {}
+
+    async def _resolve(self, tir: TirEnvelope, args: dict[str, Any]) -> TxEnvelope:
+        merged: dict[str, Any] = {**self._parties, **args}
+        return await self._trp.resolve(
+            ResolveParams(tir=tir, args=merged, env=self._environment)
+        )
+{{#each tii.transactions}}
+
+    async def {{snakeCase @key}}(self, args: {{pascalCase @key}}Params) -> TxEnvelope:
+        """Resolves the {{@key}} transaction."""
+        return await self._resolve(
+            {{constantCase @key}}_TIR,
+            {
+{{#each params.properties}}
+                "{{@key}}": args.{{snakeCase @key}},
+{{/each}}
+            },
+        )
 {{/each}}
 
     async def submit(self, params: SubmitParams) -> SubmitResponse:
-        return await self._client.submit(params)
-
-# Create a default client instance
-protocol = Client({
-    "endpoint": DEFAULT_TRP_ENDPOINT,
-    "headers": DEFAULT_HEADERS,
-    "env_args": DEFAULT_ENV_ARGS,
-})
+        """Submits a signed transaction to the network."""
+        return await self._trp.submit(params)