fix: decompose monolithic functions into focused helpers (CSM-023)

Break up SRP violations in Templates.do_update_template/2 and
Capabilities.for_project/2 by extracting domain-specific builder
functions and single-responsibility private helpers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/bds/csm023_srp_violations_test.exs

@@ -0,0 +1,85 @@
+defmodule BDS.CSM023SrpViolationsTest do
+  use ExUnit.Case, async: true
+
+  describe "Templates.do_update_template/2 decomposition" do
+    test "update_template pipeline is decomposed into focused private functions" do
+      source = File.read!("lib/bds/templates.ex")
+
+      assert source =~ "defp resolve_next_slug("
+      assert source =~ "defp content_changed?("
+      assert source =~ "defp resolve_next_status("
+      assert source =~ "defp build_update_attrs("
+      assert source =~ "defp commit_update_transaction("
+
+      refute source =~ "defp do_update_template(template, attrs) do\n    next_slug =",
+             "do_update_template should delegate to focused helpers, not inline all logic"
+    end
+
+    test "do_update_template delegates to helpers instead of inlining" do
+      source = File.read!("lib/bds/templates.ex")
+
+      [do_update_body] =
+        Regex.scan(
+          ~r/defp do_update_template\(template, attrs\) do\n(.*?)(?=\n  defp )/s,
+          source,
+          capture: :all_but_first
+        )
+        |> Enum.map(&hd/1)
+
+      assert do_update_body =~ "resolve_next_slug(template, attrs)"
+      assert do_update_body =~ "content_changed?(template, attrs)"
+      assert do_update_body =~ "resolve_next_status(template, content_changed?)"
+      assert do_update_body =~ "build_update_attrs(template, attrs, next_slug, next_status, now)"
+      assert do_update_body =~ "commit_update_transaction(template, updates, slug_changed?, now)"
+    end
+  end
+
+  describe "Capabilities.for_project/2 decomposition" do
+    test "for_project delegates to domain-specific builder functions" do
+      source = File.read!("lib/bds/scripting/capabilities.ex")
+
+      assert source =~ "defp app_capabilities("
+      assert source =~ "defp project_capabilities("
+      assert source =~ "defp meta_capabilities("
+      assert source =~ "defp post_capabilities("
+      assert source =~ "defp media_capabilities("
+      assert source =~ "defp script_capabilities("
+      assert source =~ "defp template_capabilities("
+      assert source =~ "defp tag_capabilities("
+      assert source =~ "defp task_capabilities"
+      assert source =~ "defp sync_capabilities("
+      assert source =~ "defp publish_capabilities("
+      assert source =~ "defp chat_capabilities("
+      assert source =~ "defp embedding_capabilities("
+    end
+
+    test "for_project body is a concise map of builder calls" do
+      source = File.read!("lib/bds/scripting/capabilities.ex")
+      for_project_body = extract_for_project_body(source)
+
+      line_count = for_project_body |> String.split("\n") |> length()
+
+      assert line_count <= 20,
+             "for_project body should be a concise dispatch map, got #{line_count} lines"
+    end
+
+    test "no domain-specific capability entries remain in for_project body" do
+      source = File.read!("lib/bds/scripting/capabilities.ex")
+      for_project_body = extract_for_project_body(source)
+
+      refute for_project_body =~ "one_arg(",
+             "for_project body should not contain one_arg calls directly"
+
+      refute for_project_body =~ "zero_or_one_arg(",
+             "for_project body should not contain zero_or_one_arg calls directly"
+    end
+
+    defp extract_for_project_body(source) do
+      lines = String.split(source, "\n")
+      start_idx = Enum.find_index(lines, &String.contains?(&1, "def for_project("))
+      remaining = Enum.drop(lines, start_idx + 1)
+      end_idx = Enum.find_index(remaining, &(&1 == "  end"))
+      remaining |> Enum.take(end_idx) |> Enum.join("\n")
+    end
+  end
+end