the ledger: a caller's own bedikot, read back and signed

The examination is the product; the record of it is what a caller can
carry away. Every bedikah was already engraved in L3 — output hash and
length, source digests, coupling trace, claims, violations, verdict,
never the text — and no caller could get theirs back.

- bedikot.key_id (migration): a SHA-256 digest of the courtyard key that
  brought the offering, never the key; threaded as :key_id through
  Bedikah.examine from every site that goes through the gate (courtyard
  bedikah, pair, the gate's pass and stream). Unique index on
  bedikah_ref.
- VavPipeline.Ledger: entry (the examination's fields, none of the
  database's, not the owner's), canonical JSON (keys sorted at every
  level, no whitespace, UTF-8), Ed25519 sign/verify, public key, render.
  Seed from BIKORET_LEDGER_SIGNING_KEY (base64 of 32 bytes) in
  shorashim-secrets; absent → unsigned and says so.
- GET /courtyard/ledger?limit&before — this key's bedikot, newest first,
  each rendered and signed; GET /courtyard/bedikah/<ref> — one, 404 for
  another key's or none alike; GET /peah/ledger_key — the public key.
- Tamid §1.1 "The ledger" (Doorpost pin moved → 02ddf313…), KOHEN
  "Issuing a key" (the seed, once), secrets.yaml template.

Tests: ledger_test (digest, entry, canonical, sign/verify, unsigned
rendering, signed rendering); ledger_l3_test (own records listed newest
first and only own; 404 alike for another's and none; an examination
engraved under the key reads back signed and verifies against
/peah/ledger_key). Elixir 642/0; L3 13/0.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

vav_pipeline/test/ledger_test.exs

@@ -0,0 +1,97 @@
+defmodule VavPipeline.LedgerTest do
+  @moduledoc "The provenance ledger: canonical form, signature, key digest (2026-10-21)."
+  use ExUnit.Case, async: true
+
+  alias VavPipeline.Ledger
+
+  @seed :crypto.strong_rand_bytes(32)
+
+  defp record do
+    %VavPipeline.L3.BedikahRecord{
+      id: 7,
+      bedikah_ref: "bedikah-0123456789abcdef",
+      provenance: "claude",
+      query: "q",
+      output_sha256: String.duplicate("ab", 32),
+      output_length: 12,
+      vital_content: "",
+      propositions: [],
+      references: ["Devarim 6:4"],
+      authority_claims: [],
+      actions: [],
+      sources: [%{"id" => "system", "sha256" => "00", "length" => 2}],
+      claims: [%{"index" => 1, "sentence" => "x", "anchors" => []}],
+      structure: %{"self_validation" => []},
+      frames: [],
+      rebukes: nil,
+      mesorah: [],
+      coupling_trace: [],
+      violations: [],
+      verdict: "tov",
+      examined_at: ~U[2026-10-21 12:00:00Z],
+      key_id: "deadbeef",
+      inserted_at: ~U[2026-10-21 12:00:01Z]
+    }
+  end
+
+  test "key_id is a digest of the key, never the key, and nil for none" do
+    assert Ledger.key_id(nil) == nil
+    id = Ledger.key_id("courtyard-secret-key")
+    assert String.length(id) == 32
+    refute id =~ "courtyard"
+    assert id == Ledger.key_id("courtyard-secret-key")
+    refute id == Ledger.key_id("another")
+  end
+
+  test "the entry carries the examination's fields and neither the database's nor the owner's" do
+    e = Ledger.entry(record())
+    assert Map.keys(e) |> Enum.sort() == Enum.sort(Ledger.ledger_fields())
+    refute Map.has_key?(e, :id)
+    refute Map.has_key?(e, :key_id)
+    refute Map.has_key?(e, :inserted_at)
+    assert e.examined_at == "2026-10-21T12:00:00Z"
+  end
+
+  test "canonical form sorts keys at every level and carries no whitespace" do
+    a = Ledger.canonical(%{"b" => 1, "a" => %{"z" => [%{"y" => 2, "x" => 1}], "m" => "s"}})
+    assert a == ~s({"a":{"m":"s","z":[{"x":1,"y":2}]},"b":1})
+    # the same map with keys given in another order canonicalizes the same
+    assert a == Ledger.canonical(%{"a" => %{"m" => "s", "z" => [%{"x" => 1, "y" => 2}]}, "b" => 1})
+    # atom and string keys meet in the same place
+    assert Ledger.canonical(%{b: 1, a: 2}) == ~s({"a":2,"b":1})
+  end
+
+  test "a signature verifies with the public key and fails on one changed byte" do
+    bytes = Ledger.canonical(Ledger.entry(record()))
+    sig = Ledger.sign(bytes, @seed)
+    pub = Ledger.public_key(@seed)
+    assert Ledger.verify(bytes, sig, pub)
+    refute Ledger.verify(bytes <> " ", sig, pub)
+    refute Ledger.verify(bytes, sig, Ledger.public_key(:crypto.strong_rand_bytes(32)))
+    refute Ledger.verify(bytes, "not base64!", pub)
+  end
+
+  test "without a seed nothing is signed, and the rendering says so" do
+    assert Ledger.sign("x", nil) == nil
+    assert Ledger.public_key(nil) == nil
+    r = Ledger.render(record())
+    assert r.entry.bedikah_ref == "bedikah-0123456789abcdef"
+    assert String.length(r.canonical_sha256) == 64
+    # the test env has no signing key configured
+    assert r.signed == false and r.signature == nil
+  end
+
+  test "a rendering with a seed configured is signed and self-consistent" do
+    Application.put_env(:vav_pipeline, :ledger_signing_key, Base.encode64(@seed))
+
+    try do
+      r = Ledger.render(record())
+      assert r.signed
+      bytes = Ledger.canonical(r.entry)
+      assert :crypto.hash(:sha256, bytes) |> Base.encode16(case: :lower) == r.canonical_sha256
+      assert Ledger.verify(bytes, r.signature, Ledger.public_key())
+    after
+      Application.delete_env(:vav_pipeline, :ledger_signing_key)
+    end
+  end
+end