Add failing tests for issue #409: Environment Variable Pollution

docs/prompting_guide.md

@@ -228,7 +228,7 @@ When an architecture.json entry includes a `context_urls` array, the `generate_p
 
 ```json
 "context_urls": [
-  {"url": "https://fastapi.tiangolo.com/tutorial/first-steps/", "purpose": "FastAPI routing patterns"}
+  {{"url": "https://fastapi.tiangolo.com/tutorial/first-steps/", "purpose": "FastAPI routing patterns"}}
 ]
 ```
 
@@ -312,50 +312,50 @@ The `<pdd-interface>` tag supports four interface types, matching the architectu
 
 **Module Interface** (Python modules with functions):
 ```json
-{
+{{
   "type": "module",
-  "module": {
+  "module": {{
     "functions": [
-      {"name": "func_name", "signature": "(arg1, arg2)", "returns": "Type"}
+      {{"name": "func_name", "signature": "(arg1, arg2)", "returns": "Type"}}
     ]
-  }
-}
+  }}
+}}
 ```
 
 **CLI Interface** (Command-line interfaces):
 ```json
-{
+{{
   "type": "cli",
-  "cli": {
+  "cli": {{
     "commands": [
-      {"name": "cmd_name", "description": "What it does"}
+      {{"name": "cmd_name", "description": "What it does"}}
     ]
-  }
-}
+  }}
+}}
 ```
 
 **Command Interface** (PDD commands):
 ```json
-{
+{{
   "type": "command",
-  "command": {
+  "command": {{
     "commands": [
-      {"name": "cmd_name", "description": "What it does"}
+      {{"name": "cmd_name", "description": "What it does"}}
     ]
-  }
-}
+  }}
+}}
 ```
 
 **Frontend Interface** (UI pages):
 ```json
-{
+{{
   "type": "frontend",
-  "frontend": {
+  "frontend": {{
     "pages": [
-      {"name": "page_name", "route": "/path"}
+      {{"name": "page_name", "route": "/path"}}
     ]
-  }
-}
+  }}
+}}
 ```
 
 ### Sync Workflow
@@ -823,9 +823,9 @@ Constraints:
 - Output a unified diff only
 
 Snippet:
-  export function parseUserId(input: string) {
+  export function parseUserId(input: string) {{
     return input.trim().split(":")[1];
-  }
+  }}
 ```
 
 PDD‑style prompt (source of truth):

pdd/commands/generate.py

@@ -147,10 +147,6 @@ def generate(
                 if item in os.environ:
                     env_vars[item] = os.environ[item]
 
-        # Update os.environ for the duration of this command
-        # This allows the code generator and template expansion to see these values
-        os.environ.update(env_vars)
-
         # 4. Call Code Generator
         generated_code, is_incremental, cost, model = code_generator_main(
             ctx=ctx,

tests/test_commands_generate.py

@@ -268,4 +268,39 @@ def add(a, b):
         # Print success message
         print(f"Successfully generated code at {output_path}")
     except Exception as e:
-        pytest.fail(f"Real generation test failed: {e}")
+        pytest.fail(f"Real generation test failed: {e}")
+
+
+@patch('pdd.core.cli.auto_update')
+@patch('pdd.commands.generate.code_generator_main')
+def test_issue_409_env_vars_do_not_pollute_os_environ(mock_main, mock_auto_update, runner, create_dummy_files, monkeypatch):
+    files = create_dummy_files("pollution_test.prompt")
+    mock_main.return_value = ('code', False, 0.0, 'model')
+    test_vars = {
+        'TEST_VAR_409': 'test_value',
+        'SECRET_KEY_409': 'secret123',
+        'API_TOKEN_409': 'token456'
+    }
+
+    for key in test_vars.keys():
+        monkeypatch.delenv(key, raising=False)
+    cmd_args = ["generate"]
+    for key, value in test_vars.items():
+        cmd_args.extend(["-e", f"{key}={value}"])
+    cmd_args.append(str(files["pollution_test.prompt"]))
+    result = runner.invoke(cli.cli, cmd_args)
+    assert result.exit_code == 0, f"Command failed: {result.output}"
+    call_kwargs = mock_main.call_args.kwargs
+    assert call_kwargs["env_vars"] == test_vars, "env_vars parameter should contain test variables"
+    pollution_detected = []
+
+    for key in test_vars.keys():
+        if key in os.environ:
+            pollution_detected.append(f"{key}={os.environ[key]}")
+
+    assert len(pollution_detected) == 0, (
+        f"BUG DETECTED (Issue #409): Environment variables persist after command completion! "
+        f"Polluted variables: {pollution_detected}. "
+        f"These variables were set via -e flag and should NOT exist in os.environ after the command. "
+        f"Root cause: pdd/commands/generate.py:152 calls os.environ.update(env_vars) without cleanup."
+    )