Five forms in one card, one edit to tell,
what Apple keeps, renumbers, or drops down the well.
The parameter guess was never put to the test —
this is the card that finds out which annotation is best.

Assisted-by: Claude Opus 5 via Claude Code

diff --git a/tasks/probe.rake b/tasks/probe.rake
new file mode 100644
index 0000000..e4f625d
--- /dev/null
+++ b/tasks/probe.rake
@@ -0,0 +1,91 @@
+# Probes for client behavior this server cannot reason its way to. A
+# probe is a card built to be edited by a real client and read back off
+# the wire, because what Apple does with a property is empirical and
+# every guess about it has been wrong at least once
+# (docs/macos-contacts.md).
+#
+# Seeded over HTTP rather than into the database, so the card travels
+# the same route a client's would and the dev server needs no
+# cooperation beyond running.
+
+namespace :probe do
+  # The annotation forms under test, one card so a single edit answers
+  # all five. Each is independent: whatever the client keeps, drops, or
+  # renumbers, it does to each of these on its own terms.
+  #
+  #   X-PT-GROUP            a standalone unmodeled property — the
+  #                         control, and the only form with prior
+  #                         evidence, since macOS writes X- properties
+  #                         of its own (X-ADDRESSING-GRAMMAR)
+  #   ADR;X-PT-GROUP=       an unknown parameter on a property whose
+  #                         parameter section macOS rebuilds from its
+  #                         own model — the form the plan assumed and
+  #                         the one most likely to be lost
+  #   NOTE;X-PT-GROUP=      the same on a property macOS has not been
+  #                         seen to re-parameterize
+  #   item9.X-PT-GROUP      a companion line in a property group with
+  #                         no label the client models
+  #   item8.X-PT-GROUP      a companion beside an X-ABLabel that it
+  #                         does, in case the known line is what
+  #                         anchors the group through a renumber
+  #
+  # The id is the UID: this server's cards are named by it (see
+  # ProTacts::Contact), and a PUT whose body disagrees is refused.
+  PROBE_ID = "probe-annotations"
+  PROBE_CARD = <<~CARD.gsub("\n", "\r\n")
+    BEGIN:VCARD
+    VERSION:3.0
+    N:Boole;Probe;;;
+    FN:Probe Boole
+    X-PT-GROUP:kxsv
+    ADR;TYPE=home;X-PT-GROUP=kxsv:;;7 Calculus Close;London;England;NW1 1AB;United Kingdom
+    NOTE;X-PT-GROUP=kxsv:Gate code 1854.
+    item9.ADR;TYPE=work:;;1 Long Road;London;England;NW1 1AB;United Kingdom
+    item9.X-PT-GROUP:kxsv
+    item8.TEL;TYPE=cell:+44 20 5555 0100
+    item8.X-ABLabel:household
+    item8.X-PT-GROUP:kxsv
+    UID:#{PROBE_ID}
+    END:VCARD
+  CARD
+
+  desc "Seed the annotation probe card into a running dev server (PROBE_URL to override)"
+  task :annotations do
+    require "net/http"
+    require "uri"
+
+    # rackup's default, which is what `rake dev` starts.
+    url = URI.parse(ENV.fetch("PROBE_URL", "http://localhost:9292"))
+    url.path = "/dav/addressbook/#{PROBE_ID}.vcf"
+
+    request = Net::HTTP::Put.new(url)
+    request["Content-Type"] = "text/vcard"
+    # Serve strips this header from incoming requests and sets it from
+    # the tailnet identity, so supplying one is only possible — and only
+    # meaningful — against a dev server on localhost
+    # (ProTacts::TailscaleAuth).
+    request["Tailscale-User-Login"] = ENV.fetch("PROBE_LOGIN", "probe@example.com")
+    request.body = PROBE_CARD
+
+    response = Net::HTTP.start(url.hostname, url.port) { it.request(request) }
+    abort "#{url} answered #{response.code}: #{response.body}" unless response.code.start_with?("2")
+
+    puts <<~NEXT
+      Seeded #{PROBE_ID} (#{response.code}).
+
+      1. The server needs PRO_TACTS_DEBUG=1 for the write to be logged —
+         a successful PUT is not an unhandled request, so log/unhandled
+         will not have it. Restart with `PRO_TACTS_DEBUG=1 rake dev` if
+         it is not set.
+      2. Resync the client, edit "Probe Boole" — any field, the edit
+         itself does not matter — and let the write go through.
+      3. The PUT body lands in log/dev.log after a `>>` line. Compare it
+         with the card above: which of the five forms came back, whether
+         itemN was renumbered, and whether a companion stayed with the
+         line it was grouped with.
+      4. Record what happened in docs/macos-contacts.md. Repeat on iOS,
+         which numbers item groups differently (see
+         test/fixtures/ios-exchange/05-put-contact-edit/request).
+    NEXT
+  end
+end