fix(wikis): pass If-Match ETag header on wiki page updates

The wiki page update code fetched the existing page to get
the ETag but never passed it to the PUT call — the _existing
binding discarded the response. Without the If-Match header,
concurrent edits could silently overwrite each other.

Changes:
  * lib/ado_cli/client.ex — added Client.put/4 that accepts
    extra HTTP headers (e.g. If-Match). The new 4-arity
    function passes extra_headers through do_request ->
    do_request_with_auth, where they're merged with auth
    headers. The existing 3-arity put/3 is unchanged.

  * lib/ado_cli/cli/wikis.ex — the update_page function now
    extracts the eTag from the fetched page and passes it as
    {"If-Match", etag} to Client.put/4. If the page has no
    ETag (unlikely), the PUT proceeds without it.

  * lib/ado_cli/cli/test_results.ex — replaced Jason.encode!/1
    with JSON.encode!/1 (Elixir 1.20 built-in) to silence a
    dialyzer warning.

325 tests pass, dialyzer clean, credo clean.

Author: gilbertwong96

lib/ado_cli/cli/test_results.ex

@@ -211,7 +211,7 @@ defmodule AdoCli.CLI.TestResults do
       json? = Map.get(parsed.options, :json, false)
 
       if json? do
-        writeln(Jason.encode!(%{ok: true, run: %{id: run["id"], name: name}}))
+        writeln(JSON.encode!(%{ok: true, run: %{id: run["id"], name: name}}))
       else
         writeln("")
         writeln("✓ Test run ##{run["id"]} created: #{name}")

lib/ado_cli/cli/wikis.ex

@@ -187,17 +187,23 @@ defmodule AdoCli.CLI.Wikis do
     path = Map.fetch!(parsed.options, :path)
     content = Map.fetch!(parsed.options, :content)
 
-    # Fetch existing etag
+    # Fetch the existing page to get its ETag for optimistic
+    # concurrency. The If-Match header prevents overwriting
+    # changes made by another user between our read and write.
     case Client.get("/#{URI.encode(project)}/_apis/wiki/wikis/#{URI.encode(wiki_id)}/pages", %{
-           "path" => path
+           "path" => path,
+           "includeContent" => "true"
          }) do
-      {:ok, _existing} ->
+      {:ok, existing} ->
+        etag = existing["eTag"] || ""
+        extra_headers = if etag != "", do: [{"If-Match", etag}], else: []
         body = %{"content" => content}
 
         case Client.put(
                "/#{URI.encode(project)}/_apis/wiki/wikis/#{URI.encode(wiki_id)}/pages",
                body,
-               %{"path" => path, "comment" => "Updated via ado CLI"}
+               %{"path" => path, "comment" => "Updated via ado CLI"},
+               extra_headers
              ) do
           {:ok, page} ->
             success("Page '#{page["path"]}' updated.\n")

lib/ado_cli/client.ex

@@ -70,8 +70,14 @@ defmodule AdoCli.Client do
   @doc """
   Makes a PUT request.
   """
-  def put(path, body, params \\ %{}) do
-    handle_response(do_request(:put, path, body, params))
+  def put(path, body, params \\ %{}), do: put(path, body, params, [])
+
+  @doc """
+  PUT with extra HTTP headers (e.g. If-Match for optimistic concurrency).
+  `extra_headers` is merged with the default auth headers.
+  """
+  def put(path, body, params, extra_headers) do
+    handle_response(do_request(:put, path, body, params, extra_headers))
   end
 
   # ── Private ──────────────────────────────────────────────────────────
@@ -95,21 +101,21 @@ defmodule AdoCli.Client do
 
   defp safe_decode(body), do: body
 
-  defp do_request(method, path, body, params, attempt \\ 0)
+  defp do_request(method, path, body, params, extra_headers \\ [], attempt \\ 0)
 
-  defp do_request(_method, _path, _body, _params, 3),
+  defp do_request(_method, _path, _body, _params, _extra_headers, 3),
     do: {:error, %{status: 302, body: "Too many redirects"}}
 
-  defp do_request(method, path, body, params, attempt) do
+  defp do_request(method, path, body, params, extra_headers, attempt) do
     with {:ok, org, auth_headers} <- AdoCli.Auth.resolve_auth() do
-      do_request_with_auth(method, path, body, params, attempt, org, auth_headers)
+      do_request_with_auth(method, path, body, params, attempt, org, auth_headers, extra_headers)
     end
   end
 
-  defp do_request_with_auth(method, path, body, params, attempt, org, auth_headers) do
+  defp do_request_with_auth(method, path, body, params, attempt, org, auth_headers, extra_headers) do
     url = build_url(path, params)
     full_url = inject_org(url, org)
-    headers = [{"Content-Type", "application/json"} | auth_headers]
+    headers = [{"Content-Type", "application/json"} | auth_headers] ++ extra_headers
     encoded = if body, do: JSON.encode!(body)
 
     case Finch.request(Finch.build(method, full_url, headers, encoded), AdoCli.Finch) do