diff --git a/.claude/commands/fix-issue.md b/.claude/commands/fix-issue.md
index 85c1617130a..637ed163338 100644
--- a/.claude/commands/fix-issue.md
+++ b/.claude/commands/fix-issue.md
@@ -48,6 +48,10 @@ Before writing any code:
 
 - Stage all changes with `git add`
 - Write a concise, descriptive commit message referencing the issue (e.g. `Fix login bug (#1234)`)
+- The commit message must end with a co-author line:
+  ```
+  Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
+  ```
 - Commit the changes
 
 ## Step 7: Open a PR
@@ -56,6 +60,7 @@ Before writing any code:
 2. Create a PR with `gh pr create`:
    - Title should summarize the fix
    - Body should reference the issue (`Fixes #<issue-number>`) and briefly describe what changed
+   - Body must end with: `🤖 Generated with [Claude Code](https://claude.com/claude-code)`
 3. Add labels using the GitHub REST API (required — gh pr edit is broken):
 
    ```
diff --git a/app/controllers/csv_exports_controller.rb b/app/controllers/csv_exports_controller.rb
index cf63ce943cc..57741ec390a 100644
--- a/app/controllers/csv_exports_controller.rb
+++ b/app/controllers/csv_exports_controller.rb
@@ -1,17 +1,6 @@
 # frozen_string_literal: true
 class CsvExportsController < ApplicationController
   class RunSignupsFilenameFinder
-    PRIORITIZED_FILENAME_GENERATORS = [
-      ->(run) { run.event.title },
-      ->(run) { "#{run.event.title} (#{run.title_suffix})" },
-      ->(run) { "#{run.event.title} (#{format_run_start_day(run)})" },
-      ->(run) { "#{run.event.title} (#{format_run_start_time(run)})" },
-      ->(run) { "#{run.event.title} (#{format_run_rooms(run)})" },
-      ->(run) { "#{run.event.title} (#{format_run_start_day(run)} in #{format_run_rooms(run)})" },
-      ->(run) { "#{run.event.title} (#{format_run_start_time(run)} in #{format_run_rooms(run)})" },
-      ->(run) { "#{run.event.title} (run #{run.id})" }
-    ].freeze
-
     def format_run_start_day(run)
       run.starts_at.strftime("%a")
     end
@@ -28,13 +17,28 @@ def format_run_rooms(run)
     # strategies
     def unique_filename(event, run, suffix)
       filename_generator =
-        PRIORITIZED_FILENAME_GENERATORS.find do |generator|
+        filename_generators.find do |generator|
           filenames = event.runs.map { |r| generator.call(r) }
           filenames.uniq.size == filenames.size
         end
 
       "#{filename_generator.call(run)} #{suffix}"
     end
+
+    private
+
+    def filename_generators # rubocop:disable Metrics/AbcSize
+      [
+        ->(r) { r.event.title },
+        ->(r) { "#{r.event.title} (#{r.title_suffix})" },
+        ->(r) { "#{r.event.title} (#{format_run_start_day(r)})" },
+        ->(r) { "#{r.event.title} (#{format_run_start_time(r)})" },
+        ->(r) { "#{r.event.title} (#{format_run_rooms(r)})" },
+        ->(r) { "#{r.event.title} (#{format_run_start_day(r)} in #{format_run_rooms(r)})" },
+        ->(r) { "#{r.event.title} (#{format_run_start_time(r)} in #{format_run_rooms(r)})" },
+        ->(r) { "#{r.event.title} (run #{r.id})" }
+      ]
+    end
   end
 
   include SendCsv
diff --git a/test/controllers/csv_exports_controller_test.rb b/test/controllers/csv_exports_controller_test.rb
new file mode 100644
index 00000000000..5104913a30e
--- /dev/null
+++ b/test/controllers/csv_exports_controller_test.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+require "test_helper"
+
+describe CsvExportsController::RunSignupsFilenameFinder do
+  let(:finder) { CsvExportsController::RunSignupsFilenameFinder.new }
+  let(:convention) { create(:convention) }
+  let(:event) { create(:event, convention: convention) }
+
+  describe "#unique_filename" do
+    it "disambiguates runs by start day when they share a title" do
+      run1 = create(:run, event: event, starts_at: convention.starts_at)
+      create(:run, event: event, starts_at: convention.starts_at + 1.day)
+
+      assert_equal(
+        "#{event.title} (#{run1.starts_at.strftime("%a")}) Signups",
+        finder.unique_filename(event, run1, "Signups")
+      )
+    end
+
+    it "uses just the event title when the event has only one run" do
+      run = create(:run, event: event, starts_at: convention.starts_at)
+
+      assert_equal "#{event.title} Signups", finder.unique_filename(event, run, "Signups")
+    end
+  end
+end