diff --git a/README.md b/README.md
index e358a541..a235af95 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ const payload = message({
 
 - `python/` — the established Python package.
 - `typescript/` — the ESM TypeScript package.
-- `spec/` — 79 valid fixtures, shared invalid cases, and limits.
+- `spec/` — 82 valid fixtures, shared invalid cases, capability coverage, and limits.
 - `docs/` — the Docusaurus documentation site.
 
 See the [documentation site](https://nicklambourne.github.io/slackblocks/) for installation and usage.
diff --git a/docs/docs/contributing.mdx b/docs/docs/contributing.mdx
index 896cff0c..5426427c 100644
--- a/docs/docs/contributing.mdx
+++ b/docs/docs/contributing.mdx
@@ -53,11 +53,12 @@ The Python and TypeScript conformance suites both exercise every ID in `spec/man
 
 ## Add or change a Block Kit feature
 
-1. Add or update canonical JSON in `spec/fixtures/valid/` and register it in `spec/manifest.json`.
-2. Add invalid behavior to `spec/fixtures/invalid/manifest.json` when the feature introduces a validation rule.
-3. Update `spec/limits.json` for shared scalar constraints.
-4. Implement the feature idiomatically in both packages, or record a reason in the affected skip list.
-5. Add language-native tests and update the relevant guide or executable example.
+1. Add or update canonical JSON in `spec/fixtures/valid/`, register it in `spec/manifest.json`, and link the exact official Slack reference used to validate it.
+2. Map every new JSON-producing capability to at least one valid fixture in `spec/coverage.json`.
+3. Add invalid behavior to `spec/fixtures/invalid/manifest.json` when the feature introduces a validation rule. Every scalar leaf in `spec/limits.json` must have a matching invalid case.
+4. Update `spec/limits.json` for shared scalar constraints.
+5. Implement the feature idiomatically in both packages, or record a reason in the affected skip list.
+6. Add language-native tests and update the relevant guide or executable example.
 
 When introducing a cross-language API, serialized JSON and validation outcomes are shared; public naming and construction style are language-native.
 
diff --git a/python/slackblocks/blocks.py b/python/slackblocks/blocks.py
index 3356ee01..90ecf444 100644
--- a/python/slackblocks/blocks.py
+++ b/python/slackblocks/blocks.py
@@ -26,6 +26,7 @@
     EmailInput,
     ExternalMultiSelectMenu,
     ExternalSelectMenu,
+    FileInput,
     NumberInput,
     PlainTextInput,
     RadioButtonGroup,
@@ -85,6 +86,7 @@
     RichTextInput,
     EmailInput,
     URLInput,
+    FileInput,
 )
 
 
diff --git a/python/slackblocks/elements.py b/python/slackblocks/elements.py
index de00a4a4..fe23a141 100644
--- a/python/slackblocks/elements.py
+++ b/python/slackblocks/elements.py
@@ -404,11 +404,9 @@ def __init__(
         self.max_files = validate_int(max_files, min_value=1, max_value=10, allow_none=True)
 
     def _resolve(self) -> dict[str, Any]:
-        # FileInput currently does not emit the "type" attribute; this is
-        # preserved from prior behaviour. The pre-existing #154 export work
-        # surfaced this class but did not change its rendering contract.
         return resolve(
             {
+                **self._attributes(),
                 "action_id": self.action_id,
                 "filetypes": self.filetypes,
                 "max_files": self.max_files,
diff --git a/python/test/conformance/test_conformance.py b/python/test/conformance/test_conformance.py
index f761fb2d..ea5e943b 100644
--- a/python/test/conformance/test_conformance.py
+++ b/python/test/conformance/test_conformance.py
@@ -7,27 +7,35 @@
 import pytest
 
 from slackblocks import (
+    ActionsBlock,
     Button,
+    ConfirmationDialogue,
     ContextBlock,
     DividerBlock,
     FileInput,
     HeaderBlock,
     HomeTabView,
     Image,
+    ImageBlock,
     InputBlock,
     LengthError,
+    MarkdownBlock,
     MissingRequiredError,
+    ModalView,
     MutualExclusivityError,
     NumberInput,
     Option,
+    OptionGroup,
     OverflowMenu,
     PlainText,
+    PlainTextInput,
     RangeError,
     SectionBlock,
     SlackFile,
     StaticSelectMenu,
     Text,
     TypeMismatchError,
+    VideoBlock,
 )
 from slackblocks.errors import InvalidUsageError
 
@@ -50,10 +58,23 @@ def test_valid_manifest_covers_the_entire_fixture_corpus() -> None:
         for path in (SPEC_ROOT / "fixtures" / "valid").rglob("*.json")
     }
     assert manifest["spec_version"] == "1.0.0"
-    assert len(fixture_ids) == 79
+    assert fixture_ids
+    assert len(fixture_ids) == len(manifest["fixtures"])
     assert fixture_ids == files
 
 
+def test_every_shared_json_capability_has_an_official_fixture() -> None:
+    manifest = load_json(SPEC_ROOT / "manifest.json")
+    coverage = load_json(SPEC_ROOT / "coverage.json")
+    fixtures = {fixture["id"]: fixture for fixture in manifest["fixtures"]}
+    assert coverage["spec_version"] == manifest["spec_version"]
+    for capability, fixture_ids in coverage["capabilities"].items():
+        assert fixture_ids, capability
+        for fixture_id in fixture_ids:
+            assert fixture_id in fixtures, f"{capability} -> {fixture_id}"
+            assert fixtures[fixture_id]["slack_docs"].startswith("https://docs.slack.dev/")
+
+
 def test_every_valid_fixture_is_exercised_by_a_python_construction_test() -> None:
     manifest = load_json(SPEC_ROOT / "manifest.json")
     test_source = "\n".join(
@@ -78,18 +99,197 @@ def option(value: str = "a") -> Option:
     return Option(text=PlainText("A"), value=value)
 
 
+LIMITS = load_json(SPEC_ROOT / "limits.json")
+
+
+def video(**overrides: object) -> VideoBlock:
+    inputs: dict[str, object] = {
+        "alt_text": "Video",
+        "thumbnail_url": "https://example.com/thumbnail.png",
+        "title": "Title",
+        "video_url": "https://example.com/video.mp4",
+        **overrides,
+    }
+    return VideoBlock(**inputs)  # type: ignore[arg-type]
+
+
 INVALID_CASES: dict[str, Callable[[], object]] = {
     "text-empty": lambda: Text(""),
     "text-too-long": lambda: Text("x" * 3001),
+    "button-action-id-too-long": lambda: Button(
+        text="A", action_id="x" * (LIMITS["action_id"]["max_length"] + 1)
+    ),
+    "button-text-too-long": lambda: Button(
+        text="x" * (LIMITS["button"]["text"]["max_length"] + 1), action_id="a"
+    ),
+    "button-url-too-long": lambda: Button(
+        text="A",
+        action_id="a",
+        url="x" * (LIMITS["button"]["url"]["max_length"] + 1),
+    ),
+    "button-value-too-long": lambda: Button(
+        text="A",
+        action_id="a",
+        value="x" * (LIMITS["button"]["value"]["max_length"] + 1),
+    ),
+    "confirmation-title-too-long": lambda: ConfirmationDialogue(
+        title="x" * (LIMITS["confirmation"]["title"]["max_length"] + 1),
+        text="Text",
+        confirm="Yes",
+        deny="No",
+    ),
+    "confirmation-text-too-long": lambda: ConfirmationDialogue(
+        title="Title",
+        text="x" * (LIMITS["confirmation"]["text"]["max_length"] + 1),
+        confirm="Yes",
+        deny="No",
+    ),
+    "confirmation-confirm-too-long": lambda: ConfirmationDialogue(
+        title="Title",
+        text="Text",
+        confirm="x" * (LIMITS["confirmation"]["confirm"]["max_length"] + 1),
+        deny="No",
+    ),
+    "confirmation-deny-too-long": lambda: ConfirmationDialogue(
+        title="Title",
+        text="Text",
+        confirm="Yes",
+        deny="x" * (LIMITS["confirmation"]["deny"]["max_length"] + 1),
+    ),
+    "option-text-too-long": lambda: Option(
+        text="x" * (LIMITS["option"]["text"]["max_length"] + 1), value="a"
+    ),
+    "option-value-too-long": lambda: option("x" * (LIMITS["option"]["value"]["max_length"] + 1)),
+    "option-description-too-long": lambda: Option(
+        text="A",
+        value="a",
+        description="x" * (LIMITS["option"]["description"]["max_length"] + 1),
+    ),
+    "option-group-label-too-long": lambda: OptionGroup(
+        label="x" * (LIMITS["option_group"]["label"]["max_length"] + 1),
+        options=[option()],
+    ),
+    "option-group-empty": lambda: OptionGroup(label="Group", options=[]),
+    "option-group-too-many-options": lambda: OptionGroup(
+        label="Group",
+        options=[
+            option(str(index))
+            for index in range(LIMITS["option_group"]["options"]["max_items"] + 1)
+        ],
+    ),
+    "select-placeholder-too-long": lambda: StaticSelectMenu(
+        action_id="a",
+        options=[option()],
+        placeholder="x" * (LIMITS["select"]["placeholder"]["max_length"] + 1),
+    ),
+    "select-too-many-options": lambda: StaticSelectMenu(
+        action_id="a",
+        options=[
+            option(str(index)) for index in range(LIMITS["select"]["options"]["max_items"] + 1)
+        ],
+    ),
+    "select-too-many-option-groups": lambda: StaticSelectMenu(
+        action_id="a",
+        option_groups=[
+            OptionGroup(label=f"Group {index}", options=[option()])
+            for index in range(LIMITS["select"]["option_groups"]["max_items"] + 1)
+        ],
+    ),
+    "overflow-empty": lambda: OverflowMenu("a", []),
+    "overflow-too-many-options": lambda: OverflowMenu(
+        "a",
+        [option(str(index)) for index in range(LIMITS["overflow"]["options"]["max_items"] + 1)],
+    ),
+    "file-input-max-files-too-small": lambda: FileInput(
+        action_id="a", max_files=LIMITS["file_input"]["max_files"]["min"] - 1
+    ),
+    "file-input-max-files-too-large": lambda: FileInput(
+        action_id="a", max_files=LIMITS["file_input"]["max_files"]["max"] + 1
+    ),
+    "plain-text-input-max-length-too-large": lambda: PlainTextInput(
+        action_id="a", max_length=LIMITS["plain_text_input"]["max_length"]["max"] + 1
+    ),
+    "actions-too-many-elements": lambda: ActionsBlock(
+        elements=[
+            Button(text="A", action_id=f"a-{index}")
+            for index in range(LIMITS["actions"]["elements"]["max_items"] + 1)
+        ]
+    ),
+    "context-too-many-elements": lambda: ContextBlock(
+        elements=[Text("A") for _ in range(LIMITS["context"]["elements"]["max_items"] + 1)]
+    ),
+    "header-text-too-long": lambda: HeaderBlock("x" * (LIMITS["header"]["text"]["max_length"] + 1)),
+    "image-url-too-long": lambda: ImageBlock(
+        image_url="x" * (LIMITS["image"]["image_url"]["max_length"] + 1),
+        alt_text="Alt",
+    ),
+    "image-alt-text-too-long": lambda: ImageBlock(
+        image_url="https://example.com/image.png",
+        alt_text="x" * (LIMITS["image"]["alt_text"]["max_length"] + 1),
+    ),
+    "input-label-too-long": lambda: InputBlock(
+        label="x" * (LIMITS["input"]["label"]["max_length"] + 1),
+        element=PlainTextInput(action_id="a"),
+    ),
+    "input-hint-too-long": lambda: InputBlock(
+        label="Label",
+        hint="x" * (LIMITS["input"]["hint"]["max_length"] + 1),
+        element=PlainTextInput(action_id="a"),
+    ),
+    "markdown-empty": lambda: MarkdownBlock(""),
+    "markdown-too-long": lambda: MarkdownBlock(
+        "x" * (LIMITS["markdown"]["text"]["max_length"] + 1)
+    ),
+    "section-text-too-long": lambda: SectionBlock(
+        "x" * (LIMITS["section"]["text"]["max_length"] + 1)
+    ),
+    "section-too-many-fields": lambda: SectionBlock(
+        fields=["x"] * (LIMITS["section"]["fields"]["max_items"] + 1)
+    ),
+    "section-field-too-long": lambda: SectionBlock(
+        fields=["x" * (LIMITS["section"]["fields"]["item_max_length"] + 1)]
+    ),
+    "video-alt-text-empty": lambda: video(alt_text=""),
+    "video-alt-text-too-long": lambda: video(
+        alt_text="x" * (LIMITS["video"]["alt_text"]["max_length"] + 1)
+    ),
+    "video-title-too-long": lambda: video(title="x" * (LIMITS["video"]["title"]["max_length"] + 1)),
+    "video-author-name-too-long": lambda: video(
+        author_name="x" * (LIMITS["video"]["author_name"]["max_length"] + 1)
+    ),
+    "video-description-too-long": lambda: video(
+        description="x" * (LIMITS["video"]["description"]["max_length"] + 1)
+    ),
+    "video-provider-name-too-long": lambda: video(
+        provider_name="x" * (LIMITS["video"]["provider_name"]["max_length"] + 1)
+    ),
+    "view-missing-blocks": lambda: HomeTabView(blocks=[]),
+    "view-too-many-blocks": lambda: HomeTabView(
+        blocks=[DividerBlock() for _ in range(LIMITS["view"]["blocks"]["max_items"] + 1)]
+    ),
+    "view-private-metadata-too-long": lambda: HomeTabView(
+        blocks=[DividerBlock()],
+        private_metadata="x" * (LIMITS["view"]["private_metadata"]["max_length"] + 1),
+    ),
+    "view-callback-id-too-long": lambda: HomeTabView(
+        blocks=[DividerBlock()],
+        callback_id="x" * (LIMITS["view"]["callback_id"]["max_length"] + 1),
+    ),
+    "view-title-too-long": lambda: ModalView(
+        title="x" * (LIMITS["view"]["title"]["max_length"] + 1),
+        blocks=[DividerBlock()],
+    ),
+    "view-close-too-long": lambda: ModalView(
+        title="Title",
+        close="x" * (LIMITS["view"]["close"]["max_length"] + 1),
+        blocks=[DividerBlock()],
+    ),
+    "view-submit-too-long": lambda: ModalView(
+        title="Title",
+        submit="x" * (LIMITS["view"]["submit"]["max_length"] + 1),
+        blocks=[DividerBlock()],
+    ),
     "section-missing-content": lambda: SectionBlock(),
-    "section-text-too-long": lambda: SectionBlock("x" * 3001),
-    "section-too-many-fields": lambda: SectionBlock(fields=["x"] * 11),
-    "section-field-too-long": lambda: SectionBlock(fields=["x" * 2001]),
-    "header-text-too-long": lambda: HeaderBlock("x" * 151),
-    "button-text-too-long": lambda: Button(text="x" * 76, action_id="a"),
-    "button-action-id-too-long": lambda: Button(text="A", action_id="x" * 256),
-    "option-value-too-long": lambda: option("x" * 76),
-    "overflow-too-many-options": lambda: OverflowMenu("a", [option(str(i)) for i in range(6)]),
     "static-select-options-and-groups": lambda: StaticSelectMenu(
         "a",
         options=[option()],
@@ -101,12 +301,17 @@ def option(value: str = "a") -> Option:
     "number-input-inverted-range": lambda: NumberInput(
         is_decimal_allowed=True, min_value=2, max_value=1
     ),
-    "file-input-max-files-out-of-range": lambda: FileInput(action_id="a", max_files=11),
     "context-invalid-element": lambda: ContextBlock(elements=[DividerBlock()]),
     "input-invalid-element": lambda: InputBlock(label="Label", element=Button("A", "a")),
-    "view-missing-blocks": lambda: HomeTabView(blocks=[]),
 }
 
+
+def scalar_paths(value: object, prefix: tuple[str, ...] = ()) -> set[str]:
+    if not isinstance(value, dict):
+        return {".".join(prefix)}
+    return {path for key, nested in value.items() for path in scalar_paths(nested, (*prefix, key))}
+
+
 ERROR_CATEGORIES = {
     LengthError: "length-exceeded",
     RangeError: "out-of-range",
@@ -134,6 +339,23 @@ def test_invalid_case_category(case_id: str, expected_category: str) -> None:
     assert category == expected_category
 
 
+def test_invalid_manifest_covers_every_scalar_limit() -> None:
+    cases = load_json(SPEC_ROOT / "fixtures" / "invalid" / "manifest.json")["cases"]
+    covered = {case["constraint"] for case in cases}
+    assert scalar_paths(LIMITS) <= covered
+
+
+def test_invalid_manifest_has_unique_case_ids_and_constraints() -> None:
+    cases = load_json(SPEC_ROOT / "fixtures" / "invalid" / "manifest.json")["cases"]
+    assert len({case["id"] for case in cases}) == len(cases)
+    assert len({case["constraint"] for case in cases}) == len(cases)
+
+
+def test_every_invalid_case_has_a_python_construction() -> None:
+    cases = load_json(SPEC_ROOT / "fixtures" / "invalid" / "manifest.json")["cases"]
+    assert set(INVALID_CASES) == {case["id"] for case in cases}
+
+
 def test_python_skiplist_is_empty() -> None:
     entries = [
         line
diff --git a/python/test/unit/test_elements.py b/python/test/unit/test_elements.py
index 11ea0cd5..103d6d00 100644
--- a/python/test/unit/test_elements.py
+++ b/python/test/unit/test_elements.py
@@ -15,6 +15,7 @@
     EmailInput,
     ExternalMultiSelectMenu,
     ExternalSelectMenu,
+    FileInput,
     Image,
     NumberInput,
     OverflowMenu,
@@ -152,11 +153,45 @@ def test_email_input_basic() -> None:
     assert fetch_sample(path="elements/email_input_basic.json") == repr(email_input)
 
 
+def test_file_input_basic() -> None:
+    file_input = FileInput(
+        action_id="file_input_action_id_1",
+        filetypes=["jpg", "png"],
+        max_files=5,
+    )
+    assert fetch_sample(path="elements/file_input_basic.json") == repr(file_input)
+
+
+def test_file_input_is_valid_inside_input_block() -> None:
+    from slackblocks import InputBlock
+
+    block = InputBlock(label="Upload files", element=FileInput(action_id="file_input"))
+    assert block._resolve()["element"]["type"] == "file_input"
+
+
 def test_image_basic() -> None:
     image = Image(image_url="https://ndl.im/img/logo.png", alt_text="Logo for ndl.im")
     assert fetch_sample(path="elements/image_basic.json") == repr(image)
 
 
+@pytest.mark.parametrize(
+    ("fixture_id", "slack_file"),
+    [
+        ("elements/image_slack_file_id.json", SlackFile(url=None, id="F0123456")),
+        (
+            "elements/image_slack_file_url.json",
+            SlackFile(
+                url="https://files.slack.com/files-pri/T0123456-F0123456/xyz.png",
+                id=None,
+            ),
+        ),
+    ],
+)
+def test_image_with_slack_file_fixture(fixture_id: str, slack_file: SlackFile) -> None:
+    image = Image(alt_text="An incredibly cute kitten.", slack_file=slack_file)
+    assert fetch_sample(path=fixture_id) == repr(image)
+
+
 def test_image_with_slack_file_resolves() -> None:
     """Regression test for #130: Image element must call ``_resolve()`` on
     its nested ``slack_file`` so the result is JSON-serializable."""
diff --git a/python/test/unit/test_serializability.py b/python/test/unit/test_serializability.py
index 22018455..8c65f241 100644
--- a/python/test/unit/test_serializability.py
+++ b/python/test/unit/test_serializability.py
@@ -294,8 +294,7 @@ def _serializability_check(
         "external_select",
         True,
     ),
-    # FileInput historically does not include "type" in its rendered JSON.
-    ("FileInput", lambda: FileInput(action_id="fi"), "", False),
+    ("FileInput", lambda: FileInput(action_id="fi"), "file_input", True),
     (
         "Image_with_url",
         lambda: Image(image_url="https://x.png", alt_text="alt"),
diff --git a/spec/CHANGELOG.md b/spec/CHANGELOG.md
index 17848507..dad144ee 100644
--- a/spec/CHANGELOG.md
+++ b/spec/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## 1.0.0 - 2026-08-12
 
-- Promote the 79 existing Python golden fixtures into the shared valid corpus.
+- Promote the existing Python golden fixtures into the shared valid corpus and expand it to 82 Slack-validated cases.
 - Define the cross-language validation categories and seed invalid cases.
 - Publish a shared scalar limits registry.
+- Require fixture coverage for every supported JSON capability and invalid-case coverage for every scalar limit.
diff --git a/spec/SPEC.md b/spec/SPEC.md
index 343020a3..2a7492d4 100644
--- a/spec/SPEC.md
+++ b/spec/SPEC.md
@@ -16,6 +16,10 @@ The normative categories are `length-exceeded`, `out-of-range`, `mutually-exclus
 
 Each implementation must either exercise every valid fixture and invalid case or list its ID in `conformance/skiplist.txt` with a reason. Conformance fails for unknown entries, unlisted failures, and stale skips that now pass.
 
+`coverage.json` lists every JSON-producing capability in the shared public API and the valid fixtures that exercise it. Every referenced fixture must be registered in `manifest.json` and link to the official Slack documentation used to validate its shape. Adding a shared capability requires adding it to this registry.
+
 ## Limits
 
 `limits.json` is the shared registry for stable scalar constraints. Changes to limits and fixtures must land atomically with implementation updates or explicit skip-list entries.
+
+Every scalar leaf in `limits.json` must have a corresponding invalid case whose `constraint` is the leaf's dotted path. Structural rules that are not scalar limits may have additional invalid cases.
diff --git a/spec/coverage.json b/spec/coverage.json
new file mode 100644
index 00000000..2f92de7a
--- /dev/null
+++ b/spec/coverage.json
@@ -0,0 +1,80 @@
+{
+  "spec_version": "1.0.0",
+  "capabilities": {
+    "blocks.actions": ["blocks/actions_block_checkboxes"],
+    "blocks.context": ["blocks/context_block_text_only"],
+    "blocks.divider": ["blocks/divider_block_only"],
+    "blocks.file": ["blocks/file_block_only"],
+    "blocks.header": ["blocks/header_block_only"],
+    "blocks.image": ["blocks/image_block_only"],
+    "blocks.input": ["blocks/input_block_only"],
+    "blocks.markdown": ["blocks/markdown_block_basic"],
+    "blocks.rich_text": ["blocks/rich_text_block_basic"],
+    "blocks.section": ["blocks/section_block_text_only"],
+    "blocks.table": ["blocks/table_block"],
+    "blocks.video": ["blocks/video_block_basic"],
+    "elements.button": ["elements/button_basic"],
+    "elements.checkboxes": ["elements/checkbox_basic"],
+    "elements.date_picker": ["elements/date_picker_basic"],
+    "elements.datetime_picker": ["elements/datetime_picker_basic"],
+    "elements.email_input": ["elements/email_input_basic"],
+    "elements.file_input": ["elements/file_input_basic"],
+    "elements.image": [
+      "elements/image_basic",
+      "elements/image_slack_file_id",
+      "elements/image_slack_file_url"
+    ],
+    "elements.multi_select_channels": ["elements/multi_select_channel"],
+    "elements.multi_select_conversations": ["elements/multi_select_conversation"],
+    "elements.multi_select_external": ["elements/multi_select_external"],
+    "elements.multi_select_static": ["elements/multi_select_static"],
+    "elements.multi_select_users": ["elements/multi_select_user"],
+    "elements.number_input": ["elements/number_input_basic"],
+    "elements.overflow": ["elements/overflow_menu_basic"],
+    "elements.plain_text_input": ["elements/plaintext_input_basic"],
+    "elements.radio_buttons": ["elements/radio_button_group_basic"],
+    "elements.rich_text_input": ["elements/rich_text_input_basic"],
+    "elements.select_channels": ["elements/select_menu_channel"],
+    "elements.select_conversations": ["elements/select_menu_conversation"],
+    "elements.select_external": ["elements/select_menu_external"],
+    "elements.select_static": ["elements/select_menu_static"],
+    "elements.select_users": ["elements/select_menu_user"],
+    "elements.time_picker": ["elements/timepicker_basic"],
+    "elements.url_input": ["elements/url_input_basic"],
+    "elements.workflow_button": ["elements/workflow_button_basic"],
+    "messages.attachment": ["attachments/attachment_simple"],
+    "messages.message": ["messages/message_basic"],
+    "messages.message_response": ["messages/message_response"],
+    "messages.webhook_message": ["messages/webhook_message_basic"],
+    "objects.column_settings": ["blocks/table_block"],
+    "objects.confirmation": ["objects/confirmation_dialogue_basic"],
+    "objects.conversation_filter": ["objects/conversation_filter_basic"],
+    "objects.dispatch_action_configuration": [
+      "objects/dispatch_action_configuration_basic"
+    ],
+    "objects.input_parameter": ["objects/input_parameter_basic"],
+    "objects.markdown_text": ["objects/text_markdown_basic"],
+    "objects.option": ["objects/option_basic"],
+    "objects.option_group": ["objects/option_group_basic"],
+    "objects.plain_text": ["objects/text_plaintext_basic"],
+    "objects.raw_text": ["blocks/table_block"],
+    "objects.slack_file": [
+      "elements/image_slack_file_id",
+      "elements/image_slack_file_url"
+    ],
+    "objects.trigger": ["objects/trigger_basic"],
+    "objects.workflow": ["objects/workflow_basic"],
+    "rich_text.channel": ["rich_text/rich_text_channel_basic"],
+    "rich_text.code_block": ["rich_text/rich_text_code_block_basic"],
+    "rich_text.emoji": ["rich_text/rich_text_emoji_basic"],
+    "rich_text.link": ["rich_text/rich_text_link_basic"],
+    "rich_text.list": ["rich_text/rich_text_list_basic"],
+    "rich_text.quote": ["rich_text/rich_text_quote_basic"],
+    "rich_text.section": ["rich_text/rich_text_section_basic"],
+    "rich_text.text": ["rich_text/rich_text_basic"],
+    "rich_text.user": ["rich_text/rich_text_user_basic"],
+    "rich_text.user_group": ["rich_text/rich_text_user_group_basic"],
+    "views.home_tab": ["views/hometab_view"],
+    "views.modal": ["views/modal_with_blocks"]
+  }
+}
diff --git a/spec/fixtures/invalid/manifest.json b/spec/fixtures/invalid/manifest.json
index 89831de8..e22fb3e5 100644
--- a/spec/fixtures/invalid/manifest.json
+++ b/spec/fixtures/invalid/manifest.json
@@ -14,10 +14,190 @@
       "description": "A text object longer than 3000 characters must be rejected"
     },
     {
-      "id": "section-missing-content",
-      "category": "missing-required",
-      "constraint": "section.content",
-      "description": "A section with neither text nor fields must be rejected"
+      "id": "button-action-id-too-long",
+      "category": "length-exceeded",
+      "constraint": "action_id.max_length",
+      "description": "An action ID longer than 255 characters must be rejected"
+    },
+    {
+      "id": "button-text-too-long",
+      "category": "length-exceeded",
+      "constraint": "button.text.max_length",
+      "description": "Button text longer than 75 characters must be rejected"
+    },
+    {
+      "id": "button-url-too-long",
+      "category": "length-exceeded",
+      "constraint": "button.url.max_length",
+      "description": "A button URL longer than 3000 characters must be rejected"
+    },
+    {
+      "id": "button-value-too-long",
+      "category": "length-exceeded",
+      "constraint": "button.value.max_length",
+      "description": "A button value longer than 2000 characters must be rejected"
+    },
+    {
+      "id": "confirmation-title-too-long",
+      "category": "length-exceeded",
+      "constraint": "confirmation.title.max_length",
+      "description": "A confirmation title longer than 100 characters must be rejected"
+    },
+    {
+      "id": "confirmation-text-too-long",
+      "category": "length-exceeded",
+      "constraint": "confirmation.text.max_length",
+      "description": "Confirmation text longer than 300 characters must be rejected"
+    },
+    {
+      "id": "confirmation-confirm-too-long",
+      "category": "length-exceeded",
+      "constraint": "confirmation.confirm.max_length",
+      "description": "Confirmation button text longer than 30 characters must be rejected"
+    },
+    {
+      "id": "confirmation-deny-too-long",
+      "category": "length-exceeded",
+      "constraint": "confirmation.deny.max_length",
+      "description": "Denial button text longer than 30 characters must be rejected"
+    },
+    {
+      "id": "option-text-too-long",
+      "category": "length-exceeded",
+      "constraint": "option.text.max_length",
+      "description": "Option text longer than 75 characters must be rejected"
+    },
+    {
+      "id": "option-value-too-long",
+      "category": "length-exceeded",
+      "constraint": "option.value.max_length",
+      "description": "An option value longer than 75 characters must be rejected"
+    },
+    {
+      "id": "option-description-too-long",
+      "category": "length-exceeded",
+      "constraint": "option.description.max_length",
+      "description": "An option description longer than 75 characters must be rejected"
+    },
+    {
+      "id": "option-group-label-too-long",
+      "category": "length-exceeded",
+      "constraint": "option_group.label.max_length",
+      "description": "An option-group label longer than 75 characters must be rejected"
+    },
+    {
+      "id": "option-group-empty",
+      "category": "length-exceeded",
+      "constraint": "option_group.options.min_items",
+      "description": "An option group with no options must be rejected"
+    },
+    {
+      "id": "option-group-too-many-options",
+      "category": "length-exceeded",
+      "constraint": "option_group.options.max_items",
+      "description": "An option group with more than 100 options must be rejected"
+    },
+    {
+      "id": "select-placeholder-too-long",
+      "category": "length-exceeded",
+      "constraint": "select.placeholder.max_length",
+      "description": "A select placeholder longer than 150 characters must be rejected"
+    },
+    {
+      "id": "select-too-many-options",
+      "category": "length-exceeded",
+      "constraint": "select.options.max_items",
+      "description": "A static select with more than 100 options must be rejected"
+    },
+    {
+      "id": "select-too-many-option-groups",
+      "category": "length-exceeded",
+      "constraint": "select.option_groups.max_items",
+      "description": "A static select with more than 100 option groups must be rejected"
+    },
+    {
+      "id": "overflow-empty",
+      "category": "length-exceeded",
+      "constraint": "overflow.options.min_items",
+      "description": "An overflow menu with no options must be rejected"
+    },
+    {
+      "id": "overflow-too-many-options",
+      "category": "length-exceeded",
+      "constraint": "overflow.options.max_items",
+      "description": "An overflow menu with more than five options must be rejected"
+    },
+    {
+      "id": "file-input-max-files-too-small",
+      "category": "out-of-range",
+      "constraint": "file_input.max_files.min",
+      "description": "File input max files below one must be rejected"
+    },
+    {
+      "id": "file-input-max-files-too-large",
+      "category": "out-of-range",
+      "constraint": "file_input.max_files.max",
+      "description": "File input max files above 10 must be rejected"
+    },
+    {
+      "id": "plain-text-input-max-length-too-large",
+      "category": "out-of-range",
+      "constraint": "plain_text_input.max_length.max",
+      "description": "Plain-text input max length above 3000 must be rejected"
+    },
+    {
+      "id": "actions-too-many-elements",
+      "category": "length-exceeded",
+      "constraint": "actions.elements.max_items",
+      "description": "An actions block with more than 25 elements must be rejected"
+    },
+    {
+      "id": "context-too-many-elements",
+      "category": "length-exceeded",
+      "constraint": "context.elements.max_items",
+      "description": "A context block with more than 10 elements must be rejected"
+    },
+    {
+      "id": "header-text-too-long",
+      "category": "length-exceeded",
+      "constraint": "header.text.max_length",
+      "description": "Header text longer than 150 characters must be rejected"
+    },
+    {
+      "id": "image-url-too-long",
+      "category": "length-exceeded",
+      "constraint": "image.image_url.max_length",
+      "description": "An image URL longer than 3000 characters must be rejected"
+    },
+    {
+      "id": "image-alt-text-too-long",
+      "category": "length-exceeded",
+      "constraint": "image.alt_text.max_length",
+      "description": "Image alternative text longer than 2000 characters must be rejected"
+    },
+    {
+      "id": "input-label-too-long",
+      "category": "length-exceeded",
+      "constraint": "input.label.max_length",
+      "description": "An input-block label longer than 2000 characters must be rejected"
+    },
+    {
+      "id": "input-hint-too-long",
+      "category": "length-exceeded",
+      "constraint": "input.hint.max_length",
+      "description": "Input-block hint text longer than 2000 characters must be rejected"
+    },
+    {
+      "id": "markdown-empty",
+      "category": "length-exceeded",
+      "constraint": "markdown.text.min_length",
+      "description": "An empty markdown block must be rejected"
+    },
+    {
+      "id": "markdown-too-long",
+      "category": "length-exceeded",
+      "constraint": "markdown.text.max_length",
+      "description": "Markdown block text longer than 12000 characters must be rejected"
     },
     {
       "id": "section-text-too-long",
@@ -38,34 +218,88 @@
       "description": "A section field longer than 2000 characters must be rejected"
     },
     {
-      "id": "header-text-too-long",
+      "id": "video-alt-text-empty",
       "category": "length-exceeded",
-      "constraint": "header.text.max_length",
-      "description": "Header text longer than 150 characters must be rejected"
+      "constraint": "video.alt_text.min_length",
+      "description": "A video block with empty alternative text must be rejected"
     },
     {
-      "id": "button-text-too-long",
+      "id": "video-alt-text-too-long",
       "category": "length-exceeded",
-      "constraint": "button.text.max_length",
-      "description": "Button text longer than 75 characters must be rejected"
+      "constraint": "video.alt_text.max_length",
+      "description": "Video alternative text longer than 200 characters must be rejected"
     },
     {
-      "id": "button-action-id-too-long",
+      "id": "video-title-too-long",
       "category": "length-exceeded",
-      "constraint": "action_id.max_length",
-      "description": "An action ID longer than 255 characters must be rejected"
+      "constraint": "video.title.max_length",
+      "description": "A video title longer than 200 characters must be rejected"
     },
     {
-      "id": "option-value-too-long",
+      "id": "video-author-name-too-long",
       "category": "length-exceeded",
-      "constraint": "option.value.max_length",
-      "description": "An option value longer than 75 characters must be rejected"
+      "constraint": "video.author_name.max_length",
+      "description": "A video author name longer than 50 characters must be rejected"
     },
     {
-      "id": "overflow-too-many-options",
+      "id": "video-description-too-long",
       "category": "length-exceeded",
-      "constraint": "overflow.options.max_items",
-      "description": "An overflow menu with more than five options must be rejected"
+      "constraint": "video.description.max_length",
+      "description": "A video description longer than 200 characters must be rejected"
+    },
+    {
+      "id": "video-provider-name-too-long",
+      "category": "length-exceeded",
+      "constraint": "video.provider_name.max_length",
+      "description": "A video provider name longer than 50 characters must be rejected"
+    },
+    {
+      "id": "view-missing-blocks",
+      "category": "length-exceeded",
+      "constraint": "view.blocks.min_items",
+      "description": "A view must contain at least one block"
+    },
+    {
+      "id": "view-too-many-blocks",
+      "category": "length-exceeded",
+      "constraint": "view.blocks.max_items",
+      "description": "A view with more than 100 blocks must be rejected"
+    },
+    {
+      "id": "view-private-metadata-too-long",
+      "category": "length-exceeded",
+      "constraint": "view.private_metadata.max_length",
+      "description": "View private metadata longer than 3000 characters must be rejected"
+    },
+    {
+      "id": "view-callback-id-too-long",
+      "category": "length-exceeded",
+      "constraint": "view.callback_id.max_length",
+      "description": "A view callback ID longer than 255 characters must be rejected"
+    },
+    {
+      "id": "view-title-too-long",
+      "category": "length-exceeded",
+      "constraint": "view.title.max_length",
+      "description": "A modal title longer than 24 characters must be rejected"
+    },
+    {
+      "id": "view-close-too-long",
+      "category": "length-exceeded",
+      "constraint": "view.close.max_length",
+      "description": "Modal close text longer than 24 characters must be rejected"
+    },
+    {
+      "id": "view-submit-too-long",
+      "category": "length-exceeded",
+      "constraint": "view.submit.max_length",
+      "description": "Modal submit text longer than 24 characters must be rejected"
+    },
+    {
+      "id": "section-missing-content",
+      "category": "missing-required",
+      "constraint": "section.content",
+      "description": "A section with neither text nor fields must be rejected"
     },
     {
       "id": "static-select-options-and-groups",
@@ -85,12 +319,6 @@
       "constraint": "number_input.range",
       "description": "A number input minimum cannot exceed its maximum"
     },
-    {
-      "id": "file-input-max-files-out-of-range",
-      "category": "out-of-range",
-      "constraint": "file_input.max_files",
-      "description": "File input max files must be between 1 and 10"
-    },
     {
       "id": "context-invalid-element",
       "category": "type-mismatch",
@@ -102,12 +330,6 @@
       "category": "type-mismatch",
       "constraint": "input.element",
       "description": "An input block must contain an input-compatible element"
-    },
-    {
-      "id": "view-missing-blocks",
-      "category": "length-exceeded",
-      "constraint": "view.blocks.min_items",
-      "description": "A view must contain at least one block"
     }
   ]
 }
diff --git a/spec/fixtures/valid/elements/file_input_basic.json b/spec/fixtures/valid/elements/file_input_basic.json
new file mode 100644
index 00000000..4529828f
--- /dev/null
+++ b/spec/fixtures/valid/elements/file_input_basic.json
@@ -0,0 +1,9 @@
+{
+    "type": "file_input",
+    "action_id": "file_input_action_id_1",
+    "filetypes": [
+        "jpg",
+        "png"
+    ],
+    "max_files": 5
+}
diff --git a/spec/fixtures/valid/elements/image_slack_file_id.json b/spec/fixtures/valid/elements/image_slack_file_id.json
new file mode 100644
index 00000000..d07b60ca
--- /dev/null
+++ b/spec/fixtures/valid/elements/image_slack_file_id.json
@@ -0,0 +1,7 @@
+{
+    "type": "image",
+    "slack_file": {
+        "id": "F0123456"
+    },
+    "alt_text": "An incredibly cute kitten."
+}
diff --git a/spec/fixtures/valid/elements/image_slack_file_url.json b/spec/fixtures/valid/elements/image_slack_file_url.json
new file mode 100644
index 00000000..41021217
--- /dev/null
+++ b/spec/fixtures/valid/elements/image_slack_file_url.json
@@ -0,0 +1,7 @@
+{
+    "type": "image",
+    "slack_file": {
+        "url": "https://files.slack.com/files-pri/T0123456-F0123456/xyz.png"
+    },
+    "alt_text": "An incredibly cute kitten."
+}
diff --git a/spec/manifest.json b/spec/manifest.json
index 6696bccc..ecb63133 100644
--- a/spec/manifest.json
+++ b/spec/manifest.json
@@ -157,12 +157,30 @@
       "slack_docs": "https://docs.slack.dev/reference/block-kit/block-elements/",
       "since": "1.0.0"
     },
+    {
+      "id": "elements/file_input_basic",
+      "description": "File Input Basic",
+      "slack_docs": "https://docs.slack.dev/reference/block-kit/block-elements/file-input-element/",
+      "since": "1.0.0"
+    },
     {
       "id": "elements/image_basic",
       "description": "Image Basic",
       "slack_docs": "https://docs.slack.dev/reference/block-kit/block-elements/",
       "since": "1.0.0"
     },
+    {
+      "id": "elements/image_slack_file_id",
+      "description": "Image With Slack File ID",
+      "slack_docs": "https://docs.slack.dev/reference/block-kit/composition-objects/slack-file-object/",
+      "since": "1.0.0"
+    },
+    {
+      "id": "elements/image_slack_file_url",
+      "description": "Image With Slack File URL",
+      "slack_docs": "https://docs.slack.dev/reference/block-kit/composition-objects/slack-file-object/",
+      "since": "1.0.0"
+    },
     {
       "id": "elements/multi_select_channel",
       "description": "Multi Select Channel",
diff --git a/typescript/src/elements.ts b/typescript/src/elements.ts
index 7ffee149..651bdf22 100644
--- a/typescript/src/elements.ts
+++ b/typescript/src/elements.ts
@@ -1,5 +1,5 @@
 import { RangeError } from "./errors.js";
-import { create, createObject } from "./internal.js";
+import { create } from "./internal.js";
 import { asText, type TextLike } from "./objects.js";
 import type { FactorySettings, JsonObject, SlackObject } from "./types.js";
 
@@ -82,12 +82,11 @@ export function emailInput(
 export function fileInput(
   input: { actionId: string; filetypes?: string[]; maxFiles?: number },
   settings: FactorySettings = {},
-): JsonObject {
+): SlackObject<"file_input"> {
   if (input.maxFiles !== undefined && (input.maxFiles < 1 || input.maxFiles > 10)) {
     throw new RangeError("fileInput.maxFiles", "expected a value between 1 and 10");
   }
-  // Python 2.0 fixtures preserve this historical no-type wire shape.
-  return createObject(input, settings);
+  return create("file_input", input, settings);
 }
 
 export function imageElement(
diff --git a/typescript/src/objects.ts b/typescript/src/objects.ts
index ed3d5b1c..60fed3cf 100644
--- a/typescript/src/objects.ts
+++ b/typescript/src/objects.ts
@@ -111,6 +111,17 @@ export function optionGroup(
   input: OptionGroupInput,
   settings: FactorySettings = {},
 ): JsonObject {
+  ensureLength(
+    textValue(asText(input.label, "plain_text", settings)) ?? "",
+    "optionGroup.label",
+    75,
+  );
+  if (input.options.length < 1 || input.options.length > 100) {
+    throw new LengthError(
+      "optionGroup.options",
+      `expected between 1 and 100 options, received ${input.options.length}`,
+    );
+  }
   return createObject(
     { ...input, label: asText(input.label, "plain_text", settings) },
     settings,
diff --git a/typescript/src/validation.ts b/typescript/src/validation.ts
index c882e7cd..67a82b05 100644
--- a/typescript/src/validation.ts
+++ b/typescript/src/validation.ts
@@ -49,6 +49,21 @@ function length(
   }
 }
 
+function range(
+  value: number | undefined,
+  path: string,
+  minimum?: number,
+  maximum?: number,
+): void {
+  if (value === undefined) return;
+  if (minimum !== undefined && value < minimum) {
+    throw new RangeError(path, `${value} is less than minimum ${minimum}`);
+  }
+  if (maximum !== undefined && value > maximum) {
+    throw new RangeError(path, `${value} exceeds maximum ${maximum}`);
+  }
+}
+
 function validateTextObject(object: JsonObject, path: string): void {
   const value = textValue(object);
   if (value === undefined) {
@@ -141,6 +156,30 @@ function validateKnownObject(object: JsonObject, path: string): void {
         length(object.value, child(path, "value"), undefined, limits.button.value.max_length);
       }
       break;
+    case "file_input":
+      range(
+        typeof object.max_files === "number" ? object.max_files : undefined,
+        child(path, "max_files"),
+        limits.file_input.max_files.min,
+        limits.file_input.max_files.max,
+      );
+      break;
+    case "plain_text_input":
+      range(
+        typeof object.max_length === "number" ? object.max_length : undefined,
+        child(path, "max_length"),
+        undefined,
+        limits.plain_text_input.max_length.max,
+      );
+      if (object.placeholder !== undefined) {
+        length(
+          textValue(object.placeholder),
+          child(path, "placeholder.text"),
+          undefined,
+          limits.select.placeholder.max_length,
+        );
+      }
+      break;
     case "overflow":
       if (Array.isArray(object.options)) {
         length(
@@ -159,6 +198,30 @@ function validateKnownObject(object: JsonObject, path: string): void {
           "options and option_groups cannot be provided together",
         );
       }
+      if (Array.isArray(object.options)) {
+        length(
+          object.options,
+          child(path, "options"),
+          undefined,
+          limits.select.options.max_items,
+        );
+      }
+      if (Array.isArray(object.option_groups)) {
+        length(
+          object.option_groups,
+          child(path, "option_groups"),
+          undefined,
+          limits.select.option_groups.max_items,
+        );
+      }
+      if (object.placeholder !== undefined) {
+        length(
+          textValue(object.placeholder),
+          child(path, "placeholder.text"),
+          undefined,
+          limits.select.placeholder.max_length,
+        );
+      }
       break;
     case "number_input":
       if (
@@ -176,6 +239,22 @@ function validateKnownObject(object: JsonObject, path: string): void {
           "image_url and slack_file cannot be provided together",
         );
       }
+      if (typeof object.image_url === "string") {
+        length(
+          object.image_url,
+          child(path, "image_url"),
+          undefined,
+          limits.image.image_url.max_length,
+        );
+      }
+      if (typeof object.alt_text === "string") {
+        length(
+          object.alt_text,
+          child(path, "alt_text"),
+          undefined,
+          limits.image.alt_text.max_length,
+        );
+      }
       break;
     case "context":
       if (Array.isArray(object.elements)) {
@@ -198,6 +277,20 @@ function validateKnownObject(object: JsonObject, path: string): void {
       }
       break;
     case "input": {
+      length(
+        textValue(object.label),
+        child(path, "label.text"),
+        undefined,
+        limits.input.label.max_length,
+      );
+      if (object.hint !== undefined) {
+        length(
+          textValue(object.hint),
+          child(path, "hint.text"),
+          undefined,
+          limits.input.hint.max_length,
+        );
+      }
       const elementPath = child(path, "element");
       const element = objectAt(object.element, elementPath);
       if (!INPUT_ELEMENT_TYPES.has(String(element.type))) {
@@ -205,6 +298,48 @@ function validateKnownObject(object: JsonObject, path: string): void {
       }
       break;
     }
+    case "markdown":
+      length(
+        typeof object.text === "string" ? object.text : undefined,
+        child(path, "text"),
+        limits.markdown.text.min_length,
+        limits.markdown.text.max_length,
+      );
+      break;
+    case "video":
+      length(
+        typeof object.alt_text === "string" ? object.alt_text : undefined,
+        child(path, "alt_text"),
+        limits.video.alt_text.min_length,
+        limits.video.alt_text.max_length,
+      );
+      length(
+        textValue(object.title),
+        child(path, "title.text"),
+        undefined,
+        limits.video.title.max_length,
+      );
+      length(
+        typeof object.author_name === "string" ? object.author_name : undefined,
+        child(path, "author_name"),
+        undefined,
+        limits.video.author_name.max_length,
+      );
+      if (object.description !== undefined) {
+        length(
+          textValue(object.description),
+          child(path, "description.text"),
+          undefined,
+          limits.video.description.max_length,
+        );
+      }
+      length(
+        typeof object.provider_name === "string" ? object.provider_name : undefined,
+        child(path, "provider_name"),
+        undefined,
+        limits.video.provider_name.max_length,
+      );
+      break;
     case "modal":
     case "home":
       if (!Array.isArray(object.blocks)) {
@@ -216,6 +351,42 @@ function validateKnownObject(object: JsonObject, path: string): void {
         limits.view.blocks.min_items,
         limits.view.blocks.max_items,
       );
+      length(
+        typeof object.private_metadata === "string" ? object.private_metadata : undefined,
+        child(path, "private_metadata"),
+        undefined,
+        limits.view.private_metadata.max_length,
+      );
+      length(
+        typeof object.callback_id === "string" ? object.callback_id : undefined,
+        child(path, "callback_id"),
+        undefined,
+        limits.view.callback_id.max_length,
+      );
+      if (type === "modal") {
+        length(
+          textValue(object.title),
+          child(path, "title.text"),
+          undefined,
+          limits.view.title.max_length,
+        );
+        if (object.close !== undefined) {
+          length(
+            textValue(object.close),
+            child(path, "close.text"),
+            undefined,
+            limits.view.close.max_length,
+          );
+        }
+        if (object.submit !== undefined) {
+          length(
+            textValue(object.submit),
+            child(path, "submit.text"),
+            undefined,
+            limits.view.submit.max_length,
+          );
+        }
+      }
       break;
     default:
       break;
diff --git a/typescript/test/conformance.test.ts b/typescript/test/conformance.test.ts
index bd726a35..ca8ea9f3 100644
--- a/typescript/test/conformance.test.ts
+++ b/typescript/test/conformance.test.ts
@@ -4,6 +4,8 @@ import { fileURLToPath } from "node:url";
 
 import { describe, expect, it } from "vitest";
 
+import limits from "../../spec/limits.json" with { type: "json" };
+
 import {
   actionsBlock,
   attachment,
@@ -75,14 +77,24 @@ import {
 const PACKAGE_ROOT = resolve(dirname(fileURLToPath(import.meta.url)), "..");
 const SPEC_ROOT = resolve(PACKAGE_ROOT, "../spec");
 
+interface ManifestFixture {
+  id: string;
+  slack_docs: string;
+}
+
 interface Manifest {
   spec_version: string;
-  fixtures: Array<{ id: string }>;
+  fixtures: ManifestFixture[];
+}
+
+interface Coverage {
+  spec_version: string;
+  capabilities: Record<string, string[]>;
 }
 
 interface InvalidManifest {
   spec_version: string;
-  cases: Array<{ id: string; category: ErrorCategory }>;
+  cases: Array<{ id: string; category: ErrorCategory; constraint: string }>;
 }
 
 function readJson<T>(path: string): T {
@@ -213,11 +225,37 @@ function constructFixture(id: string, expected: FixtureInput): unknown {
 }
 
 const manifest = readJson<Manifest>(resolve(SPEC_ROOT, "manifest.json"));
+const coverage = readJson<Coverage>(resolve(SPEC_ROOT, "coverage.json"));
+
+function scalarPaths(value: unknown, prefix: string[] = []): string[] {
+  if (value === null || typeof value !== "object" || Array.isArray(value)) {
+    return [prefix.join(".")];
+  }
+  return Object.entries(value).flatMap(([key, nested]) =>
+    scalarPaths(nested, [...prefix, key]),
+  );
+}
 
 describe("valid conformance corpus", () => {
-  it("declares spec 1.0.0 and all 79 fixtures", () => {
+  it("declares the current spec and a non-empty fixture corpus", () => {
     expect(manifest.spec_version).toBe("1.0.0");
-    expect(manifest.fixtures).toHaveLength(79);
+    expect(manifest.fixtures.length).toBeGreaterThan(0);
+    expect(new Set(manifest.fixtures.map(({ id }) => id)).size).toBe(
+      manifest.fixtures.length,
+    );
+  });
+
+  it("covers every declared shared JSON capability with an official fixture", () => {
+    expect(coverage.spec_version).toBe(manifest.spec_version);
+    const fixtures = new Map(manifest.fixtures.map((fixture) => [fixture.id, fixture]));
+    for (const [capability, fixtureIds] of Object.entries(coverage.capabilities)) {
+      expect(fixtureIds.length, capability).toBeGreaterThan(0);
+      for (const fixtureId of fixtureIds) {
+        const fixture = fixtures.get(fixtureId);
+        expect(fixture, `${capability} -> ${fixtureId}`).toBeDefined();
+        expect(fixture?.slack_docs).toMatch(/^https:\/\/docs\.slack\.dev\//);
+      }
+    }
   });
 
   for (const fixture of manifest.fixtures) {
@@ -249,20 +287,199 @@ describe("valid conformance corpus", () => {
 });
 
 const choice = () => option({ text: "A", value: "a" });
+const video = (overrides: Record<string, unknown> = {}) =>
+  videoBlock({
+    altText: "Video",
+    thumbnailUrl: "https://example.com/thumbnail.png",
+    title: "Title",
+    videoUrl: "https://example.com/video.mp4",
+    ...overrides,
+  });
 
 const invalidCases: Record<string, () => unknown> = {
   "text-empty": () => plainText(""),
   "text-too-long": () => plainText("x".repeat(3001)),
-  "section-missing-content": () => sectionBlock({}),
-  "section-text-too-long": () => sectionBlock({ text: "x".repeat(3001) }),
-  "section-too-many-fields": () => sectionBlock({ fields: Array(11).fill("x") }),
-  "section-field-too-long": () => sectionBlock({ fields: ["x".repeat(2001)] }),
-  "header-text-too-long": () => headerBlock({ text: "x".repeat(151) }),
-  "button-text-too-long": () => button({ text: "x".repeat(76), actionId: "a" }),
-  "button-action-id-too-long": () => button({ text: "A", actionId: "x".repeat(256) }),
-  "option-value-too-long": () => option({ text: "A", value: "x".repeat(76) }),
+  "button-action-id-too-long": () =>
+    button({ text: "A", actionId: "x".repeat(limits.action_id.max_length + 1) }),
+  "button-text-too-long": () =>
+    button({ text: "x".repeat(limits.button.text.max_length + 1), actionId: "a" }),
+  "button-url-too-long": () =>
+    button({ text: "A", actionId: "a", url: "x".repeat(limits.button.url.max_length + 1) }),
+  "button-value-too-long": () =>
+    button({
+      text: "A",
+      actionId: "a",
+      value: "x".repeat(limits.button.value.max_length + 1),
+    }),
+  "confirmation-title-too-long": () =>
+    confirmation({
+      title: "x".repeat(limits.confirmation.title.max_length + 1),
+      text: "Text",
+      confirm: "Yes",
+      deny: "No",
+    }),
+  "confirmation-text-too-long": () =>
+    confirmation({
+      title: "Title",
+      text: "x".repeat(limits.confirmation.text.max_length + 1),
+      confirm: "Yes",
+      deny: "No",
+    }),
+  "confirmation-confirm-too-long": () =>
+    confirmation({
+      title: "Title",
+      text: "Text",
+      confirm: "x".repeat(limits.confirmation.confirm.max_length + 1),
+      deny: "No",
+    }),
+  "confirmation-deny-too-long": () =>
+    confirmation({
+      title: "Title",
+      text: "Text",
+      confirm: "Yes",
+      deny: "x".repeat(limits.confirmation.deny.max_length + 1),
+    }),
+  "option-text-too-long": () =>
+    option({ text: "x".repeat(limits.option.text.max_length + 1), value: "a" }),
+  "option-value-too-long": () =>
+    option({ text: "A", value: "x".repeat(limits.option.value.max_length + 1) }),
+  "option-description-too-long": () =>
+    option({
+      text: "A",
+      value: "a",
+      description: "x".repeat(limits.option.description.max_length + 1),
+    }),
+  "option-group-label-too-long": () =>
+    optionGroup({
+      label: "x".repeat(limits.option_group.label.max_length + 1),
+      options: [choice()],
+    }),
+  "option-group-empty": () => optionGroup({ label: "Group", options: [] }),
+  "option-group-too-many-options": () =>
+    optionGroup({
+      label: "Group",
+      options: Array.from({ length: limits.option_group.options.max_items + 1 }, choice),
+    }),
+  "select-placeholder-too-long": () =>
+    staticSelect({
+      actionId: "a",
+      options: [choice()],
+      placeholder: "x".repeat(limits.select.placeholder.max_length + 1),
+    }),
+  "select-too-many-options": () =>
+    staticSelect({
+      actionId: "a",
+      options: Array.from({ length: limits.select.options.max_items + 1 }, choice),
+    }),
+  "select-too-many-option-groups": () =>
+    staticSelect({
+      actionId: "a",
+      optionGroups: Array.from(
+        { length: limits.select.option_groups.max_items + 1 },
+        () => optionGroup({ label: "Group", options: [choice()] }),
+      ),
+    }),
+  "overflow-empty": () => overflow({ actionId: "a", options: [] }),
   "overflow-too-many-options": () =>
-    overflow({ actionId: "a", options: Array.from({ length: 6 }, choice) }),
+    overflow({
+      actionId: "a",
+      options: Array.from({ length: limits.overflow.options.max_items + 1 }, choice),
+    }),
+  "file-input-max-files-too-small": () =>
+    fileInput({ actionId: "a", maxFiles: limits.file_input.max_files.min - 1 }),
+  "file-input-max-files-too-large": () =>
+    fileInput({ actionId: "a", maxFiles: limits.file_input.max_files.max + 1 }),
+  "plain-text-input-max-length-too-large": () =>
+    plainTextInput({
+      actionId: "a",
+      maxLength: limits.plain_text_input.max_length.max + 1,
+    }),
+  "actions-too-many-elements": () =>
+    actionsBlock({
+      elements: Array.from({ length: limits.actions.elements.max_items + 1 }, () =>
+        button({ text: "A", actionId: "a" }),
+      ),
+    }),
+  "context-too-many-elements": () =>
+    contextBlock({
+      elements: Array.from(
+        { length: limits.context.elements.max_items + 1 },
+        () => mrkdwn("A"),
+      ),
+    }),
+  "header-text-too-long": () =>
+    headerBlock({ text: "x".repeat(limits.header.text.max_length + 1) }),
+  "image-url-too-long": () =>
+    imageBlock({ imageUrl: "x".repeat(limits.image.image_url.max_length + 1), altText: "Alt" }),
+  "image-alt-text-too-long": () =>
+    imageBlock({
+      imageUrl: "https://example.com/image.png",
+      altText: "x".repeat(limits.image.alt_text.max_length + 1),
+    }),
+  "input-label-too-long": () =>
+    inputBlock({
+      label: "x".repeat(limits.input.label.max_length + 1),
+      element: plainTextInput({ actionId: "a" }),
+    }),
+  "input-hint-too-long": () =>
+    inputBlock({
+      label: "Label",
+      hint: "x".repeat(limits.input.hint.max_length + 1),
+      element: plainTextInput({ actionId: "a" }),
+    }),
+  "markdown-empty": () => markdownBlock({ text: "" }),
+  "markdown-too-long": () =>
+    markdownBlock({ text: "x".repeat(limits.markdown.text.max_length + 1) }),
+  "section-text-too-long": () =>
+    sectionBlock({ text: "x".repeat(limits.section.text.max_length + 1) }),
+  "section-too-many-fields": () =>
+    sectionBlock({ fields: Array(limits.section.fields.max_items + 1).fill("x") }),
+  "section-field-too-long": () =>
+    sectionBlock({ fields: ["x".repeat(limits.section.fields.item_max_length + 1)] }),
+  "video-alt-text-empty": () => video({ altText: "" }),
+  "video-alt-text-too-long": () =>
+    video({ altText: "x".repeat(limits.video.alt_text.max_length + 1) }),
+  "video-title-too-long": () =>
+    video({ title: "x".repeat(limits.video.title.max_length + 1) }),
+  "video-author-name-too-long": () =>
+    video({ authorName: "x".repeat(limits.video.author_name.max_length + 1) }),
+  "video-description-too-long": () =>
+    video({ description: "x".repeat(limits.video.description.max_length + 1) }),
+  "video-provider-name-too-long": () =>
+    video({ providerName: "x".repeat(limits.video.provider_name.max_length + 1) }),
+  "view-missing-blocks": () => homeTab({ blocks: [] }),
+  "view-too-many-blocks": () =>
+    homeTab({
+      blocks: Array.from({ length: limits.view.blocks.max_items + 1 }, () => dividerBlock()),
+    }),
+  "view-private-metadata-too-long": () =>
+    homeTab({
+      blocks: [dividerBlock()],
+      privateMetadata: "x".repeat(limits.view.private_metadata.max_length + 1),
+    }),
+  "view-callback-id-too-long": () =>
+    homeTab({
+      blocks: [dividerBlock()],
+      callbackId: "x".repeat(limits.view.callback_id.max_length + 1),
+    }),
+  "view-title-too-long": () =>
+    modal({
+      title: "x".repeat(limits.view.title.max_length + 1),
+      blocks: [dividerBlock()],
+    }),
+  "view-close-too-long": () =>
+    modal({
+      title: "Title",
+      close: "x".repeat(limits.view.close.max_length + 1),
+      blocks: [dividerBlock()],
+    }),
+  "view-submit-too-long": () =>
+    modal({
+      title: "Title",
+      submit: "x".repeat(limits.view.submit.max_length + 1),
+      blocks: [dividerBlock()],
+    }),
+  "section-missing-content": () => sectionBlock({}),
   "static-select-options-and-groups": () =>
     staticSelect({ actionId: "a", options: [choice()], optionGroups: [{ label: plainText("A") }] }),
   "image-url-and-slack-file": () =>
@@ -273,11 +490,9 @@ const invalidCases: Record<string, () => unknown> = {
     } as any),
   "number-input-inverted-range": () =>
     numberInput({ actionId: "a", isDecimalAllowed: true, minValue: 2, maxValue: 1 }),
-  "file-input-max-files-out-of-range": () => fileInput({ actionId: "a", maxFiles: 11 }),
   "context-invalid-element": () => contextBlock({ elements: [dividerBlock()] }),
   "input-invalid-element": () =>
     inputBlock({ label: "Label", element: button({ text: "A", actionId: "a" }) }),
-  "view-missing-blocks": () => homeTab({ blocks: [] }),
 };
 
 const invalidManifest = readJson<InvalidManifest>(
@@ -285,6 +500,19 @@ const invalidManifest = readJson<InvalidManifest>(
 );
 
 describe("invalid conformance corpus", () => {
+  it("exercises every scalar limit in the shared registry", () => {
+    const covered = new Set(invalidManifest.cases.map(({ constraint }) => constraint));
+    expect(scalarPaths(limits).filter((path) => !covered.has(path))).toEqual([]);
+  });
+
+  it("contains unique case IDs and constraints", () => {
+    expect(new Set(invalidManifest.cases.map(({ id }) => id)).size).toBe(
+      invalidManifest.cases.length,
+    );
+    expect(new Set(invalidManifest.cases.map(({ constraint }) => constraint)).size).toBe(
+      invalidManifest.cases.length,
+    );
+  });
   it("has a construction for every case", () => {
     expect(Object.keys(invalidCases).sort()).toEqual(
       invalidManifest.cases.map(({ id }) => id).sort(),