Point README source links at v1.2.0 and guard against staleness

Author: kipcole9

README.md

@@ -59,7 +59,7 @@ Localize ships a [Claude Code](https://claude.com/claude-code) skill that teache
 /plugin install localize@localize
 ```
 
-The skill source lives in [skills/localize](https://github.com/elixir-localize/localize/blob/v1.1.1/skills/localize/SKILL.md).
+The skill source lives in [skills/localize](https://github.com/elixir-localize/localize/blob/v1.2.0/skills/localize/SKILL.md).
 
 ## MCP server
 
@@ -364,4 +364,4 @@ Locale-aware Phoenix LiveView inputs, so a user can enter a value under their ow
 
 ## License
 
-Apache License 2.0, together with the Unicode License v3 for the CLDR and UCD data embedded in the package. See the [LICENSE](https://github.com/elixir-localize/localize/blob/v1.1.1/LICENSE.md) file for details, including which Unicode data is used and what it becomes.
+Apache License 2.0, together with the Unicode License v3 for the CLDR and UCD data embedded in the package. See the [LICENSE](https://github.com/elixir-localize/localize/blob/v1.2.0/LICENSE.md) file for details, including which Unicode data is used and what it becomes.

test/localize/readme_links_test.exs

@@ -0,0 +1,47 @@
+defmodule Localize.ReadmeLinksTest do
+  @moduledoc """
+  The README's links to source files carry the version in their path, and
+  nothing regenerates them — unlike the `mix.exs` package links, which
+  interpolate `@version`. They were left pointing at the previous release
+  twice in a row, once serving a LICENSE that predated the change the release
+  was about, so the check is here rather than in a reviewer's memory.
+
+  """
+
+  use ExUnit.Case, async: true
+
+  @source_links ~r{https://github\.com/elixir-localize/localize/blob/v([0-9]+\.[0-9]+\.[0-9]+)/}
+
+  test "every versioned source link points at the current version" do
+    version = Localize.MixProject.project()[:version]
+    readme = File.read!(Path.join(__DIR__, "../../README.md"))
+
+    stale =
+      @source_links
+      |> Regex.scan(readme)
+      |> Enum.map(fn [_match, pinned] -> pinned end)
+      |> Enum.uniq()
+      |> Enum.reject(&(&1 == version))
+
+    assert stale == [],
+           "README links to v#{Enum.join(stale, ", v")} but the package is v#{version}. " <>
+             "Update the blob/v… paths in README.md to v#{version}."
+  end
+
+  test "guide and module links resolve to hexdocs rather than GitHub" do
+    # A GitHub blob link drops the reader out of the rendered documentation
+    # into raw markdown. Only genuine source files with no hexdocs page — the
+    # licence, the skill definition — belong on GitHub.
+    readme = File.read!(Path.join(__DIR__, "../../README.md"))
+
+    offenders =
+      ~r{https://github\.com/elixir-localize/localize/blob/v[0-9.]+/([^\s\)]+)}
+      |> Regex.scan(readme)
+      |> Enum.map(fn [_match, path] -> path end)
+      |> Enum.reject(&(&1 in ["LICENSE.md", "skills/localize/SKILL.md"]))
+
+    assert offenders == [],
+           "These README links go to GitHub but have a rendered hexdocs page: " <>
+             Enum.join(offenders, ", ")
+  end
+end