diff --git a/CLAUDE.md b/CLAUDE.md
index 960aa89..5b31478 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -19,7 +19,9 @@ PackageRequest = dict[str, Any]
 
 **NEVER Modify Generated Files Directly**
 
-Files in `src/adcp/types/generated_poc/` are auto-generated by `scripts/generate_types.py`. Any manual edits will be lost on regeneration.
+Files in `src/adcp/types/generated_poc/` and `src/adcp/types/generated.py` are auto-generated by `scripts/generate_types.py`. Any manual edits will be lost on regeneration.
+
+**CRITICAL**: Do not add code to `generated.py` or any files in `generated_poc/` directory. These are regenerated from schemas.
 
 **Post-Generation Fix System:**
 
@@ -64,6 +66,100 @@ Edit `scripts/post_generate_fixes.py` and add a new function. The script:
 - Validates fixes were successfully applied
 - Fails loudly if schema changes break the fix patterns
 
+## Semantic Type Aliases for Discriminated Unions
+
+**Problem**: The code generator (`datamodel-code-generator`) creates numbered type names for discriminated union variants (e.g., `PreviewRender1`, `PreviewRender2`, `SubAsset1`, `SubAsset2`). While functionally correct, these don't convey semantic meaning.
+
+**Solution**: Add semantic type aliases in `src/adcp/types/aliases.py` that provide clear, descriptive names based on the discriminator field value.
+
+**Process for Adding New Semantic Aliases:**
+
+1. **Identify the discriminated union types** - Look for numbered types (e.g., `TypeName1`, `TypeName2`) in generated files
+2. **Determine the discriminator field** - Check the schema/generated code for the `Literal` field that distinguishes variants
+3. **Create semantic aliases in `aliases.py`**:
+   ```python
+   # Import the generated types
+   from adcp.types.generated import PreviewRender1, PreviewRender2, PreviewRender3
+
+   # Create semantic aliases based on discriminator values
+   UrlPreviewRender = PreviewRender1  # output_format='url'
+   HtmlPreviewRender = PreviewRender2  # output_format='html'
+   BothPreviewRender = PreviewRender3  # output_format='both'
+   ```
+
+4. **Add to exports** in `aliases.py`:
+   ```python
+   __all__ = [
+       ...,
+       "UrlPreviewRender",
+       "HtmlPreviewRender",
+       "BothPreviewRender",
+   ]
+   ```
+
+5. **Re-export from main package** in `src/adcp/__init__.py`:
+   ```python
+   from adcp.types.aliases import (
+       ...,
+       UrlPreviewRender,
+       HtmlPreviewRender,
+       BothPreviewRender,
+   )
+
+   __all__ = [
+       ...,
+       "UrlPreviewRender",
+       "HtmlPreviewRender",
+       "BothPreviewRender",
+   ]
+   ```
+
+6. **Add comprehensive tests** in `tests/test_type_aliases.py`:
+   - Test that aliases can be imported
+   - Test that aliases point to correct generated types
+   - Test that aliases are exported from main package
+
+**Current Semantic Aliases:**
+
+- **Preview Renders** (discriminated by `output_format`):
+  - `UrlPreviewRender` = `PreviewRender1` (output_format='url')
+  - `HtmlPreviewRender` = `PreviewRender2` (output_format='html')
+  - `BothPreviewRender` = `PreviewRender3` (output_format='both')
+
+- **VAST Assets** (discriminated by `delivery_type`):
+  - `UrlVastAsset` = `VastAsset1` (delivery_type='url')
+  - `InlineVastAsset` = `VastAsset2` (delivery_type='inline')
+
+- **DAAST Assets** (discriminated by `delivery_type`):
+  - `UrlDaastAsset` = `DaastAsset1` (delivery_type='url')
+  - `InlineDaastAsset` = `DaastAsset2` (delivery_type='inline')
+
+- **SubAssets** (discriminated by `asset_kind`):
+  - `MediaSubAsset` = `SubAsset1` (asset_kind='media')
+  - `TextSubAsset` = `SubAsset2` (asset_kind='text')
+
+- **Response Types** (discriminated by success/error):
+  - Success/Error variants for: ActivateSignal, BuildCreative, CreateMediaBuy, ProvidePerformanceFeedback, SyncCreatives, UpdateMediaBuy
+
+- **Request Types** (discriminated by operation variant):
+  - `PreviewCreativeFormatRequest`/`PreviewCreativeManifestRequest`
+  - `UpdateMediaBuyPackagesRequest`/`UpdateMediaBuyPropertiesRequest`
+
+- **Activation Keys** (discriminated by identifier type):
+  - `PropertyIdActivationKey`/`PropertyTagActivationKey`
+
+**Guidelines for Choosing What to Alias:**
+
+✅ **DO create aliases for:**
+- User-facing discriminated unions used in API calls
+- Types where the discriminator conveys important semantic meaning
+- Types where numbered suffixes cause confusion
+
+❌ **DON'T create aliases for:**
+- Internal helper types not commonly used directly
+- Types where parent context makes the meaning clear
+- Generic helper types (Input1, Parameters2, etc.)
+
 **Type Checking Best Practices**
 - Use `TYPE_CHECKING` for optional dependencies to avoid runtime import errors
 - Use `cast()` for JSON deserialization to satisfy mypy's `no-any-return` checks
diff --git a/src/adcp/__init__.py b/src/adcp/__init__.py
index 4e5cc10..2a95e3d 100644
--- a/src/adcp/__init__.py
+++ b/src/adcp/__init__.py
@@ -56,27 +56,33 @@
 from adcp.types.aliases import (
     ActivateSignalErrorResponse,
     ActivateSignalSuccessResponse,
+    BothPreviewRender,
     BuildCreativeErrorResponse,
     BuildCreativeSuccessResponse,
     CreateMediaBuyErrorResponse,
     CreateMediaBuySuccessResponse,
+    HtmlPreviewRender,
+    InlineDaastAsset,
+    InlineVastAsset,
+    MediaSubAsset,
     PreviewCreativeFormatRequest,
     PreviewCreativeInteractiveResponse,
     PreviewCreativeManifestRequest,
     PreviewCreativeStaticResponse,
-    PreviewRenderHtml,
-    PreviewRenderIframe,
-    PreviewRenderImage,
     PropertyIdActivationKey,
     PropertyTagActivationKey,
     ProvidePerformanceFeedbackErrorResponse,
     ProvidePerformanceFeedbackSuccessResponse,
     SyncCreativesErrorResponse,
     SyncCreativesSuccessResponse,
+    TextSubAsset,
     UpdateMediaBuyErrorResponse,
     UpdateMediaBuyPackagesRequest,
     UpdateMediaBuyPropertiesRequest,
     UpdateMediaBuySuccessResponse,
+    UrlDaastAsset,
+    UrlPreviewRender,
+    UrlVastAsset,
 )
 from adcp.types.core import AgentConfig, Protocol, TaskResult, TaskStatus, WebhookMetadata
 
@@ -219,25 +225,31 @@
     # Semantic type aliases (for better API ergonomics)
     "ActivateSignalSuccessResponse",
     "ActivateSignalErrorResponse",
+    "BothPreviewRender",
     "BuildCreativeSuccessResponse",
     "BuildCreativeErrorResponse",
     "CreateMediaBuySuccessResponse",
     "CreateMediaBuyErrorResponse",
-    "ProvidePerformanceFeedbackSuccessResponse",
-    "ProvidePerformanceFeedbackErrorResponse",
-    "SyncCreativesSuccessResponse",
-    "SyncCreativesErrorResponse",
-    "UpdateMediaBuySuccessResponse",
-    "UpdateMediaBuyErrorResponse",
+    "HtmlPreviewRender",
+    "InlineDaastAsset",
+    "InlineVastAsset",
+    "MediaSubAsset",
     "PreviewCreativeFormatRequest",
     "PreviewCreativeManifestRequest",
     "PreviewCreativeStaticResponse",
     "PreviewCreativeInteractiveResponse",
-    "PreviewRenderImage",
-    "PreviewRenderHtml",
-    "PreviewRenderIframe",
     "PropertyIdActivationKey",
     "PropertyTagActivationKey",
+    "ProvidePerformanceFeedbackSuccessResponse",
+    "ProvidePerformanceFeedbackErrorResponse",
+    "SyncCreativesSuccessResponse",
+    "SyncCreativesErrorResponse",
+    "TextSubAsset",
+    "UpdateMediaBuySuccessResponse",
+    "UpdateMediaBuyErrorResponse",
     "UpdateMediaBuyPackagesRequest",
     "UpdateMediaBuyPropertiesRequest",
+    "UrlDaastAsset",
+    "UrlPreviewRender",
+    "UrlVastAsset",
 ]
diff --git a/src/adcp/types/__init__.py b/src/adcp/types/__init__.py
index 30ff4ac..f57eae6 100644
--- a/src/adcp/types/__init__.py
+++ b/src/adcp/types/__init__.py
@@ -2,6 +2,17 @@
 
 """Type definitions for AdCP client."""
 
+from adcp.types.aliases import (
+    BothPreviewRender,
+    HtmlPreviewRender,
+    InlineDaastAsset,
+    InlineVastAsset,
+    MediaSubAsset,
+    TextSubAsset,
+    UrlDaastAsset,
+    UrlPreviewRender,
+    UrlVastAsset,
+)
 from adcp.types.base import AdCPBaseModel
 from adcp.types.core import (
     Activity,
@@ -24,4 +35,14 @@
     "Activity",
     "ActivityType",
     "DebugInfo",
+    # Semantic aliases for discriminated unions
+    "BothPreviewRender",
+    "HtmlPreviewRender",
+    "InlineDaastAsset",
+    "InlineVastAsset",
+    "MediaSubAsset",
+    "TextSubAsset",
+    "UrlDaastAsset",
+    "UrlPreviewRender",
+    "UrlVastAsset",
 ]
diff --git a/src/adcp/types/aliases.py b/src/adcp/types/aliases.py
index 11feaf9..bd391b0 100644
--- a/src/adcp/types/aliases.py
+++ b/src/adcp/types/aliases.py
@@ -45,6 +45,9 @@
     # Create media buy responses
     CreateMediaBuyResponse1,
     CreateMediaBuyResponse2,
+    # DAAST assets
+    DaastAsset1,
+    DaastAsset2,
     # Preview creative requests
     PreviewCreativeRequest1,
     PreviewCreativeRequest2,
@@ -58,6 +61,9 @@
     # Performance feedback responses
     ProvidePerformanceFeedbackResponse1,
     ProvidePerformanceFeedbackResponse2,
+    # SubAssets
+    SubAsset1,
+    SubAsset2,
     # Sync creatives responses
     SyncCreativesResponse1,
     SyncCreativesResponse2,
@@ -67,6 +73,9 @@
     # Update media buy responses
     UpdateMediaBuyResponse1,
     UpdateMediaBuyResponse2,
+    # VAST assets
+    VastAsset1,
+    VastAsset2,
 )
 
 # ============================================================================
@@ -157,15 +166,40 @@
 PreviewCreativeInteractiveResponse = PreviewCreativeResponse2
 """Preview response with interactive renders (iframe embedding)."""
 
-# Preview Render Variants
-PreviewRenderImage = PreviewRender1
-"""Image-based preview render (PNG/JPEG)."""
+# Preview Render Variants (discriminated by output_format)
+UrlPreviewRender = PreviewRender1
+"""Preview render with output_format='url' - provides preview_url for iframe embedding."""
 
-PreviewRenderHtml = PreviewRender2
-"""HTML-based preview render (static markup)."""
+HtmlPreviewRender = PreviewRender2
+"""Preview render with output_format='html' - provides preview_html for direct embedding."""
 
-PreviewRenderIframe = PreviewRender3
-"""Interactive iframe-based preview render."""
+BothPreviewRender = PreviewRender3
+"""Preview render with output_format='both' - provides both preview_url and preview_html."""
+
+# ============================================================================
+# ASSET TYPE ALIASES - Delivery & Kind Discriminated Unions
+# ============================================================================
+
+# VAST Asset Variants (discriminated by delivery_type)
+UrlVastAsset = VastAsset1
+"""VAST asset delivered via URL endpoint - delivery_type='url'."""
+
+InlineVastAsset = VastAsset2
+"""VAST asset with inline XML content - delivery_type='inline'."""
+
+# DAAST Asset Variants (discriminated by delivery_type)
+UrlDaastAsset = DaastAsset1
+"""DAAST asset delivered via URL endpoint - delivery_type='url'."""
+
+InlineDaastAsset = DaastAsset2
+"""DAAST asset with inline XML content - delivery_type='inline'."""
+
+# SubAsset Variants (discriminated by asset_kind)
+MediaSubAsset = SubAsset1
+"""SubAsset for media content (images, videos) - asset_kind='media', provides content_uri."""
+
+TextSubAsset = SubAsset2
+"""SubAsset for text content (headlines, body text) - asset_kind='text', provides content."""
 
 # ============================================================================
 # EXPORTS
@@ -178,6 +212,16 @@
     # Activation keys
     "PropertyIdActivationKey",
     "PropertyTagActivationKey",
+    # Asset type aliases
+    "BothPreviewRender",
+    "HtmlPreviewRender",
+    "InlineDaastAsset",
+    "InlineVastAsset",
+    "MediaSubAsset",
+    "TextSubAsset",
+    "UrlDaastAsset",
+    "UrlPreviewRender",
+    "UrlVastAsset",
     # Build creative responses
     "BuildCreativeSuccessResponse",
     "BuildCreativeErrorResponse",
@@ -193,10 +237,6 @@
     # Preview creative responses
     "PreviewCreativeStaticResponse",
     "PreviewCreativeInteractiveResponse",
-    # Preview renders
-    "PreviewRenderImage",
-    "PreviewRenderHtml",
-    "PreviewRenderIframe",
     # Sync creatives responses
     "SyncCreativesSuccessResponse",
     "SyncCreativesErrorResponse",
diff --git a/tests/test_discriminated_unions.py b/tests/test_discriminated_unions.py
index 42d49d4..0b3edd4 100644
--- a/tests/test_discriminated_unions.py
+++ b/tests/test_discriminated_unions.py
@@ -9,8 +9,17 @@
 from adcp import (
     ActivateSignalErrorResponse,
     ActivateSignalSuccessResponse,
+    BothPreviewRender,
     CreateMediaBuyErrorResponse,
     CreateMediaBuySuccessResponse,
+    HtmlPreviewRender,
+    InlineDaastAsset,
+    InlineVastAsset,
+    MediaSubAsset,
+    TextSubAsset,
+    UrlDaastAsset,
+    UrlPreviewRender,
+    UrlVastAsset,
 )
 
 # Keep using generated names for authorization/deployment/destination variants
@@ -448,3 +457,254 @@ def test_product_accepts_mixed_publisher_properties(self):
         assert len(mixed_props) == 2
         assert mixed_props[0].selection_type == "by_id"
         assert mixed_props[1].selection_type == "by_tag"
+
+
+class TestPreviewRenderDiscriminators:
+    """Test PreviewRender discriminator field values match semantic aliases."""
+
+    def test_url_preview_render_has_url_discriminator(self):
+        """UrlPreviewRender has output_format='url'."""
+        render = UrlPreviewRender(
+            render_id="render_1",
+            role="primary",
+            output_format="url",
+            preview_url="https://preview.example.com/creative",
+        )
+        assert render.output_format == "url"
+        assert hasattr(render, "preview_url")
+        assert not hasattr(render, "preview_html")
+
+    def test_html_preview_render_has_html_discriminator(self):
+        """HtmlPreviewRender has output_format='html'."""
+        render = HtmlPreviewRender(
+            render_id="render_1",
+            role="primary",
+            output_format="html",
+            preview_html="<div>Preview HTML</div>",
+        )
+        assert render.output_format == "html"
+        assert hasattr(render, "preview_html")
+        assert not hasattr(render, "preview_url")
+
+    def test_both_preview_render_has_both_discriminator(self):
+        """BothPreviewRender has output_format='both'."""
+        render = BothPreviewRender(
+            render_id="render_1",
+            role="primary",
+            output_format="both",
+            preview_url="https://preview.example.com/creative",
+            preview_html="<div>Preview HTML</div>",
+        )
+        assert render.output_format == "both"
+        assert hasattr(render, "preview_url")
+        assert hasattr(render, "preview_html")
+
+    def test_url_preview_render_rejects_wrong_discriminator(self):
+        """UrlPreviewRender rejects output_format='html'."""
+        with pytest.raises(ValidationError) as exc_info:
+            UrlPreviewRender(
+                render_id="render_1",
+                role="primary",
+                output_format="html",  # Wrong discriminator value
+                preview_url="https://preview.example.com/creative",
+            )
+        assert "output_format" in str(exc_info.value).lower()
+
+    def test_html_preview_render_rejects_wrong_discriminator(self):
+        """HtmlPreviewRender rejects output_format='url'."""
+        with pytest.raises(ValidationError) as exc_info:
+            HtmlPreviewRender(
+                render_id="render_1",
+                role="primary",
+                output_format="url",  # Wrong discriminator value
+                preview_html="<div>Preview HTML</div>",
+            )
+        assert "output_format" in str(exc_info.value).lower()
+
+
+class TestVastAssetDiscriminators:
+    """Test VastAsset discriminator field values match semantic aliases."""
+
+    def test_url_vast_asset_has_url_discriminator(self):
+        """UrlVastAsset has delivery_type='url'."""
+        asset = UrlVastAsset(
+            delivery_type="url",
+            url="https://vast.example.com/ad.xml",
+        )
+        assert asset.delivery_type == "url"
+        assert hasattr(asset, "url")
+        assert not hasattr(asset, "vast_xml")
+
+    def test_inline_vast_asset_has_inline_discriminator(self):
+        """InlineVastAsset has delivery_type='inline'."""
+        asset = InlineVastAsset(
+            delivery_type="inline",
+            content="<VAST>...</VAST>",
+        )
+        assert asset.delivery_type == "inline"
+        assert hasattr(asset, "content")
+        assert not hasattr(asset, "url")
+
+    def test_url_vast_asset_rejects_wrong_discriminator(self):
+        """UrlVastAsset rejects delivery_type='inline'."""
+        with pytest.raises(ValidationError) as exc_info:
+            UrlVastAsset(
+                delivery_type="inline",  # Wrong discriminator value
+                url="https://vast.example.com/ad.xml",
+            )
+        assert "delivery_type" in str(exc_info.value).lower()
+
+    def test_inline_vast_asset_rejects_wrong_discriminator(self):
+        """InlineVastAsset rejects delivery_type='url'."""
+        with pytest.raises(ValidationError) as exc_info:
+            InlineVastAsset(
+                delivery_type="url",  # Wrong discriminator value
+                content="<VAST>...</VAST>",
+            )
+        assert "delivery_type" in str(exc_info.value).lower()
+
+
+class TestDaastAssetDiscriminators:
+    """Test DaastAsset discriminator field values match semantic aliases."""
+
+    def test_url_daast_asset_has_url_discriminator(self):
+        """UrlDaastAsset has delivery_type='url'."""
+        asset = UrlDaastAsset(
+            delivery_type="url",
+            url="https://daast.example.com/ad.xml",
+        )
+        assert asset.delivery_type == "url"
+        assert hasattr(asset, "url")
+        assert not hasattr(asset, "content")
+
+    def test_inline_daast_asset_has_inline_discriminator(self):
+        """InlineDaastAsset has delivery_type='inline'."""
+        asset = InlineDaastAsset(
+            delivery_type="inline",
+            content="<DAAST>...</DAAST>",
+        )
+        assert asset.delivery_type == "inline"
+        assert hasattr(asset, "content")
+        assert not hasattr(asset, "url")
+
+    def test_url_daast_asset_rejects_wrong_discriminator(self):
+        """UrlDaastAsset rejects delivery_type='inline'."""
+        with pytest.raises(ValidationError) as exc_info:
+            UrlDaastAsset(
+                delivery_type="inline",  # Wrong discriminator value
+                url="https://daast.example.com/ad.xml",
+            )
+        assert "delivery_type" in str(exc_info.value).lower()
+
+    def test_inline_daast_asset_rejects_wrong_discriminator(self):
+        """InlineDaastAsset rejects delivery_type='url'."""
+        with pytest.raises(ValidationError) as exc_info:
+            InlineDaastAsset(
+                delivery_type="url",  # Wrong discriminator value
+                content="<DAAST>...</DAAST>",
+            )
+        assert "delivery_type" in str(exc_info.value).lower()
+
+
+class TestSubAssetDiscriminators:
+    """Test SubAsset discriminator field values match semantic aliases."""
+
+    def test_media_sub_asset_has_media_discriminator(self):
+        """MediaSubAsset has asset_kind='media'."""
+        asset = MediaSubAsset(
+            asset_id="asset_1",
+            asset_type="logo",
+            asset_kind="media",
+            content_uri="https://cdn.example.com/logo.png",
+        )
+        assert asset.asset_kind == "media"
+        assert hasattr(asset, "content_uri")
+        assert not hasattr(asset, "content")
+
+    def test_text_sub_asset_has_text_discriminator(self):
+        """TextSubAsset has asset_kind='text'."""
+        asset = TextSubAsset(
+            asset_id="asset_2",
+            asset_type="headline",
+            asset_kind="text",
+            content="Buy Now!",
+        )
+        assert asset.asset_kind == "text"
+        assert hasattr(asset, "content")
+        assert not hasattr(asset, "content_uri")
+
+    def test_media_sub_asset_rejects_wrong_discriminator(self):
+        """MediaSubAsset rejects asset_kind='text'."""
+        with pytest.raises(ValidationError) as exc_info:
+            MediaSubAsset(
+                asset_id="asset_1",
+                asset_type="logo",
+                asset_kind="text",  # Wrong discriminator value
+                content_uri="https://cdn.example.com/logo.png",
+            )
+        assert "asset_kind" in str(exc_info.value).lower()
+
+    def test_text_sub_asset_rejects_wrong_discriminator(self):
+        """TextSubAsset rejects asset_kind='media'."""
+        with pytest.raises(ValidationError) as exc_info:
+            TextSubAsset(
+                asset_id="asset_2",
+                asset_type="headline",
+                asset_kind="media",  # Wrong discriminator value
+                content="Buy Now!",
+            )
+        assert "asset_kind" in str(exc_info.value).lower()
+
+
+class TestSemanticAliasDiscriminatorRoundtrips:
+    """Test that semantic aliases serialize/deserialize with correct discriminators."""
+
+    def test_url_preview_render_roundtrip(self):
+        """UrlPreviewRender roundtrips with output_format='url'."""
+        original = UrlPreviewRender(
+            render_id="render_1",
+            role="primary",
+            output_format="url",
+            preview_url="https://preview.example.com/creative",
+        )
+        json_str = original.model_dump_json()
+        parsed = UrlPreviewRender.model_validate_json(json_str)
+        assert parsed.output_format == "url"
+        assert parsed.preview_url == original.preview_url
+
+    def test_url_vast_asset_roundtrip(self):
+        """UrlVastAsset roundtrips with delivery_type='url'."""
+        original = UrlVastAsset(
+            delivery_type="url",
+            url="https://vast.example.com/ad.xml",
+        )
+        json_str = original.model_dump_json()
+        parsed = UrlVastAsset.model_validate_json(json_str)
+        assert parsed.delivery_type == "url"
+        assert parsed.url == original.url
+
+    def test_media_sub_asset_roundtrip(self):
+        """MediaSubAsset roundtrips with asset_kind='media'."""
+        original = MediaSubAsset(
+            asset_id="asset_1",
+            asset_type="logo",
+            asset_kind="media",
+            content_uri="https://cdn.example.com/logo.png",
+        )
+        json_str = original.model_dump_json()
+        parsed = MediaSubAsset.model_validate_json(json_str)
+        assert parsed.asset_kind == "media"
+        assert parsed.content_uri == original.content_uri
+
+    def test_text_sub_asset_roundtrip(self):
+        """TextSubAsset roundtrips with asset_kind='text'."""
+        original = TextSubAsset(
+            asset_id="asset_2",
+            asset_type="headline",
+            asset_kind="text",
+            content="Buy Now!",
+        )
+        json_str = original.model_dump_json()
+        parsed = TextSubAsset.model_validate_json(json_str)
+        assert parsed.asset_kind == "text"
+        assert parsed.content == original.content
diff --git a/tests/test_type_aliases.py b/tests/test_type_aliases.py
index e7394ef..7977811 100644
--- a/tests/test_type_aliases.py
+++ b/tests/test_type_aliases.py
@@ -12,10 +12,19 @@
 from adcp import (
     ActivateSignalErrorResponse,
     ActivateSignalSuccessResponse,
+    BothPreviewRender,
     BuildCreativeErrorResponse,
     BuildCreativeSuccessResponse,
     CreateMediaBuyErrorResponse,
     CreateMediaBuySuccessResponse,
+    HtmlPreviewRender,
+    InlineDaastAsset,
+    InlineVastAsset,
+    MediaSubAsset,
+    TextSubAsset,
+    UrlDaastAsset,
+    UrlPreviewRender,
+    UrlVastAsset,
 )
 
 # Test that aliases can also be imported from the aliases module
@@ -165,11 +174,12 @@ def test_all_activation_key_aliases_exported():
 def test_all_preview_render_aliases_exported():
     """Test that all preview render aliases are exported."""
     expected_aliases = [
-        "PreviewRenderImage",
-        "PreviewRenderHtml",
-        "PreviewRenderIframe",
         "PreviewCreativeStaticResponse",
         "PreviewCreativeInteractiveResponse",
+        # Semantic aliases based on output_format discriminator
+        "UrlPreviewRender",
+        "HtmlPreviewRender",
+        "BothPreviewRender",
     ]
 
     import adcp.types.aliases as aliases_module
@@ -177,3 +187,98 @@ def test_all_preview_render_aliases_exported():
     for alias in expected_aliases:
         assert hasattr(aliases_module, alias), f"Missing alias: {alias}"
         assert alias in aliases_module.__all__, f"Alias not in __all__: {alias}"
+
+
+def test_all_asset_type_aliases_exported():
+    """Test that all asset type aliases are exported."""
+    expected_aliases = [
+        # VAST assets
+        "UrlVastAsset",
+        "InlineVastAsset",
+        # DAAST assets
+        "UrlDaastAsset",
+        "InlineDaastAsset",
+        # SubAssets
+        "MediaSubAsset",
+        "TextSubAsset",
+    ]
+
+    import adcp.types.aliases as aliases_module
+
+    for alias in expected_aliases:
+        assert hasattr(aliases_module, alias), f"Missing alias: {alias}"
+        assert alias in aliases_module.__all__, f"Alias not in __all__: {alias}"
+
+
+def test_discriminated_union_aliases_point_to_correct_types():
+    """Test that discriminated union aliases point to the correct generated types."""
+    from adcp.types.generated import (
+        DaastAsset1,
+        DaastAsset2,
+        PreviewRender1,
+        PreviewRender2,
+        PreviewRender3,
+        SubAsset1,
+        SubAsset2,
+        VastAsset1,
+        VastAsset2,
+    )
+
+    # Preview renders
+    assert UrlPreviewRender is PreviewRender1
+    assert HtmlPreviewRender is PreviewRender2
+    assert BothPreviewRender is PreviewRender3
+
+    # VAST assets
+    assert UrlVastAsset is VastAsset1
+    assert InlineVastAsset is VastAsset2
+
+    # DAAST assets
+    assert UrlDaastAsset is DaastAsset1
+    assert InlineDaastAsset is DaastAsset2
+
+    # SubAssets
+    assert MediaSubAsset is SubAsset1
+    assert TextSubAsset is SubAsset2
+
+
+def test_semantic_aliases_can_be_imported_from_main_package():
+    """Test that new semantic aliases can be imported from the main adcp package."""
+    from adcp import (
+        BothPreviewRender as MainBothPreviewRender,
+    )
+    from adcp import (
+        HtmlPreviewRender as MainHtmlPreviewRender,
+    )
+    from adcp import (
+        InlineDaastAsset as MainInlineDaastAsset,
+    )
+    from adcp import (
+        InlineVastAsset as MainInlineVastAsset,
+    )
+    from adcp import (
+        MediaSubAsset as MainMediaSubAsset,
+    )
+    from adcp import (
+        TextSubAsset as MainTextSubAsset,
+    )
+    from adcp import (
+        UrlDaastAsset as MainUrlDaastAsset,
+    )
+    from adcp import (
+        UrlPreviewRender as MainUrlPreviewRender,
+    )
+    from adcp import (
+        UrlVastAsset as MainUrlVastAsset,
+    )
+
+    # Verify they match the aliases module exports
+    assert MainUrlPreviewRender is UrlPreviewRender
+    assert MainHtmlPreviewRender is HtmlPreviewRender
+    assert MainBothPreviewRender is BothPreviewRender
+    assert MainUrlVastAsset is UrlVastAsset
+    assert MainInlineVastAsset is InlineVastAsset
+    assert MainUrlDaastAsset is UrlDaastAsset
+    assert MainInlineDaastAsset is InlineDaastAsset
+    assert MainMediaSubAsset is MediaSubAsset
+    assert MainTextSubAsset is TextSubAsset