diff --git a/SPECGAPS.md b/SPECGAPS.md
index 78b5f4d..922821a 100644
--- a/SPECGAPS.md
+++ b/SPECGAPS.md
@@ -19,7 +19,7 @@ Gap categories: **SC** = spec correct, fix code | **CS** = code correct, update
 | A1-7 | ~~Template lookup must use all 4 levels (post→tag→category→default)~~ | template_context.allium:267-277 | `resolve_post_template_slug/3` implements tag→category cascade; all callers (preview, generation) updated | **Resolved:** `resolve_post_template_slug/3` in template_selection.ex, callers in preview.ex, router.ex, outputs.ex updated, 8 tests added |
 | A1-8 | ~~`ValidateLiquid`/`ValidateScript` before publish~~ | template.allium:110, script.allium:165 | `publish_template` validates Liquid via `Liquex.parse`, `publish_script` validates Lua via `BDS.Scripting.validate` | **Resolved:** validation gates added to `publish_template/1` and `publish_script/1`, invalid content returns `{:error, {:invalid_liquid|:invalid_script, reason}}`, 4 tests added |
 | A1-9 | ~~17 preset colors + custom hex in tag picker~~ | editor_tags.allium | `ColourPicker` hook + popover with 17 preset swatches grid and custom hex input, wired to both create and edit forms | **Resolved:** replaced native `<input type="color">` with `ColourPickerPopover` component (17 presets, custom hex #RRGGBB, immediate selection), JS hook for click-away dismiss, 1 test added |
-| A1-10 | Template file written on create | engine_side_effects.allium:151-153 | Draft templates have `file_path=""` | Fix code: write template file on create |
+| A1-10 | ~~Template file written on create~~ | engine_side_effects.allium:151-153 | `create_template` now computes `file_path` and writes template file with YAML frontmatter on create | **Resolved:** `create_template/1` writes `templates/{slug}.liquid` on create, `next_template_file_path` always computes path, 1 test added |
 | A1-11 | Graceful shutdown with inflight request tracking | preview.allium:47-48 | Kills acceptor process, no inflight tracking | Fix code: track inflight requests, drain before shutdown |
 | A1-12 | Real Pagefind integration for search | generation.allium:208 | Stub only: `pagefind-ui.js` is one-liner, `PagefindUI` never defined, search-runtime.js silently bails, client-side search non-functional | Fix code: bundle real Pagefind, build proper fragment index, wire PagefindUI |
 | A1-13 | Git sidebar shows only "Working tree" placeholder | sidebar_views.allium:651-770 | `sidebar.ex:782-798` returns single entity_list item; `BDS.Git` has full status/diff/commit/history/fetch/pull/push/prune_lfs but sidebar doesn't use it | Fix code: wire sidebar `git_view/0` to `BDS.Git` — render branch, ahead/behind, status file list, commit input, history entries, action buttons per spec |
diff --git a/lib/bds/templates.ex b/lib/bds/templates.ex
index 1254ee6..3c9548f 100644
--- a/lib/bds/templates.ex
+++ b/lib/bds/templates.ex
@@ -28,23 +28,38 @@ defmodule BDS.Templates do
     now = Persistence.now_ms()
     project_id = attr(attrs, :project_id)
     title = attr(attrs, :title) || ""
+    slug = unique_slug(project_id, Slug.slugify(title), "template")
+    file_path = template_file_path(slug)
 
-    %Template{}
-    |> Template.changeset(%{
-      id: Ecto.UUID.generate(),
-      project_id: project_id,
-      slug: unique_slug(project_id, Slug.slugify(title), "template"),
-      title: title,
-      kind: attr(attrs, :kind),
-      enabled: true,
-      version: 1,
-      file_path: "",
-      status: :draft,
-      content: attr(attrs, :content),
-      created_at: now,
-      updated_at: now
-    })
-    |> Repo.insert()
+    changeset =
+      %Template{}
+      |> Template.changeset(%{
+        id: Ecto.UUID.generate(),
+        project_id: project_id,
+        slug: slug,
+        title: title,
+        kind: attr(attrs, :kind),
+        enabled: true,
+        version: 1,
+        file_path: file_path,
+        status: :draft,
+        content: attr(attrs, :content),
+        created_at: now,
+        updated_at: now
+      })
+
+    with {:ok, template} <- Repo.insert(changeset) do
+      full_path = full_file_path(template.project_id, file_path)
+      File.mkdir_p!(Path.dirname(full_path))
+
+      :ok =
+        Persistence.atomic_write(
+          full_path,
+          serialize_template_file(template, template.content || "")
+        )
+
+      {:ok, template}
+    end
   end
 
   @spec get_template(String.t()) :: Template.t() | nil
@@ -348,7 +363,6 @@ defmodule BDS.Templates do
     Path.join(Projects.project_data_dir(project), relative_path)
   end
 
-  defp next_template_file_path(%Template{file_path: ""}, _next_slug), do: ""
   defp next_template_file_path(%Template{}, next_slug), do: template_file_path(next_slug)
 
   defp serialize_template_file(template, content) do
diff --git a/test/bds/templates_test.exs b/test/bds/templates_test.exs
index b9ac764..8f75b61 100644
--- a/test/bds/templates_test.exs
+++ b/test/bds/templates_test.exs
@@ -29,7 +29,7 @@ defmodule BDS.TemplatesTest do
     assert template.status == :draft
     assert template.enabled == true
     assert template.version == 1
-    assert template.file_path == ""
+    assert template.file_path == "templates/article-view.liquid"
     assert template.content == "<article>{{ content }}</article>"
 
     assert {:ok, duplicate} =
@@ -43,6 +43,28 @@ defmodule BDS.TemplatesTest do
     assert duplicate.slug == "article-view-2"
   end
 
+  test "create_template writes template file to disk", %{project: project, temp_dir: temp_dir} do
+    assert {:ok, template} =
+             BDS.Templates.create_template(%{
+               project_id: project.id,
+               title: "My Layout",
+               kind: :post,
+               content: "<main>{{ content }}</main>"
+             })
+
+    assert template.file_path == "templates/my-layout.liquid"
+
+    full_path = Path.join(temp_dir, template.file_path)
+    assert File.exists?(full_path)
+
+    contents = File.read!(full_path)
+    assert contents =~ "---\nid: #{template.id}\n"
+    assert contents =~ "slug: my-layout\n"
+    assert contents =~ "title: My Layout\n"
+    assert contents =~ "kind: post\n"
+    assert contents =~ "\n---\n<main>{{ content }}</main>\n"
+  end
+
   test "publish_template writes a liquid file with frontmatter and clears draft content", %{
     project: project,
     temp_dir: temp_dir