Tablet 45: the courtyard gate checks the key, not the shape of the header

/courtyard/* and /chatzer/* admitted any `Authorization: Bearer <x>`.
Every test sent `Bearer test-token`; none sent a wrong one. Every
admitted request spends the day's manna.

VavPipeline.BigdeiKodesh.Gate: keys are a file (Construction §4.6 —
never env, never config, never git), one `tier key` per line, tiers
courtyard < chatzer (the inner ring opens the outer). Constant-time
compare against every line; no file / empty / unreadable → nobody
passes, GATE_NO_KEYS in the log, the caller told only "missing or
invalid". 403 FORBIDDEN for an outer key at an inner gate. Read on
every request so a rotated key is live in ~1 min without a rollout.

Deploy: Secret shorashim-api-keys projected at
/etc/shorashim/secrets/api_keys (vav-pipeline only, 0440),
API_KEYS_FILE in the configmap, template + issue/rotate recipe in
secrets.yaml and KOHEN.md "Issuing a key". Spec: tamid §1.1 (gate,
403), vayakhel §4.6. Doorpost 91d09d8d… → 42b38626….
Tests: tablet45_gate_test (parse, tiers, wrong/near/empty/no key, no
file) — Elixir 527/0.

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

KOHEN.md

@@ -488,6 +488,29 @@ curl https://shorashim.ch/kodesh/status | jq .halt_status
 curl https://shorashim.ch/kodesh/status | jq '.refuge_components'
 ```
 
+### Issuing a key — *Mishmeret HaSha'ar*
+
+The courtyard and the chatzer open only to a key you issued. Keys live
+in the `shorashim-api-keys` Secret, mounted as a file; the gate reads
+the file on every request, so a change takes effect within about a
+minute, without a rollout. One line per key: `courtyard <key>` (offerings,
+bedikot) or `chatzer <key>` (also the Sanhedrin; opens the courtyard too).
+
+```bash
+umask 077; TMP=$(mktemp)
+kubectl get secret shorashim-api-keys -n shorashim -o jsonpath='{.data.api_keys}' \
+  | base64 -d > "$TMP" 2>/dev/null || true          # existing keys, if any
+printf 'courtyard %s\n' "$(openssl rand -hex 32)" >> "$TMP"
+kubectl create secret generic shorashim-api-keys -n shorashim \
+  --from-file=api_keys="$TMP" --dry-run=client -o yaml | kubectl apply -f -
+tail -1 "$TMP"      # hand this line's key to its bearer, then
+rm -f "$TMP"
+```
+
+To revoke: remove the line the same way. Without the Secret the pod
+does not start; with an empty file nobody passes (`GATE_NO_KEYS` in the
+vav-pipeline log).
+
 ### Checking a model's output — *Bedikah*
 
 The external check (Tamid §1.1, *lo taaseh lekha* §9.1). Hand it any

deploy/k8s/configmap.yaml

@@ -20,6 +20,11 @@ data:
   # shared tmp-shorashim volume. Pod-internal; never on the network.
   KORBAN_SOCKET_PATH: "/tmp/shorashim/korban.sock"
 
+  # Courtyard / chatzer keys — a FILE (Construction §4.6), projected from
+  # the shorashim-api-keys Secret (secrets.yaml). The path is config; the
+  # keys never are.
+  API_KEYS_FILE: "/etc/shorashim/secrets/api_keys"
+
   # Shoresh Engine binary — staged onto the shared shoresh-bin volume
   # by the shoresh-engine-install init container (see deployment.yaml).
   # vav_pipeline spawns it as an Erlang Port, i.e. as a child process of

deploy/k8s/deployment.yaml

@@ -76,6 +76,13 @@ spec:
         # vav-pipeline, which spawns it as an Erlang Port.
         - name: shoresh-bin
           emptyDir: {}
+        # The courtyard keys, as a file (Construction §4.6). Only
+        # vav-pipeline mounts it. Absent → the pod waits at
+        # ContainerCreating, loudly; there is no "open gate" fallback.
+        - name: api-keys
+          secret:
+            secretName: shorashim-api-keys
+            defaultMode: 0440
 
       # --- POD SECURITY CONTEXT ---
       # Every image runs as the non-root user `shorashim` (uid/gid
@@ -221,6 +228,9 @@ spec:
             # directory both live under it.
             - name: tmp-shorashim
               mountPath: /tmp
+            - name: api-keys
+              mountPath: /etc/shorashim/secrets
+              readOnly: true
             - name: shoresh-bin
               mountPath: /opt/shoresh
               readOnly: true

deploy/k8s/secrets.yaml

@@ -88,3 +88,38 @@ type: Opaque
 stringData:
   # ecto://avnadmin:PASSWORD@host:port/database?sslmode=require
   DATABASE_URL: "REPLACE_WITH_AVNADMIN_DATABASE_URL"
+
+---
+# ============================================================
+# shorashim-api-keys — who may enter the courtyard
+# ============================================================
+#
+# Mounted as the file /etc/shorashim/secrets/api_keys in vav-pipeline
+# (Construction §4.6: a secret is a file). One key per line:
+#
+#   courtyard <key>     offerings and bedikot (/courtyard/*)
+#   chatzer   <key>     also the Sanhedrin (/chatzer/*); opens the courtyard too
+#
+# Issue a key (KOHEN.md "Issuing a key"):
+#
+#   umask 077; TMP=$(mktemp)
+#   printf 'courtyard %s\n' "$(openssl rand -hex 32)" >> "$TMP"
+#   kubectl create secret generic shorashim-api-keys -n shorashim \
+#     --from-file=api_keys="$TMP"
+#   # rotate: kubectl create ... --dry-run=client -o yaml | kubectl apply -f -
+#   rm -f "$TMP"
+#
+# The kubelet refreshes a projected Secret within about a minute; the
+# gate reads the file on every request, so a rotated key takes effect
+# without a rollout. No file, no keys → nobody passes (GATE_NO_KEYS in
+# the log).
+apiVersion: v1
+kind: Secret
+metadata:
+  name: shorashim-api-keys
+  namespace: shorashim
+type: Opaque
+stringData:
+  api_keys: |
+    # tier  key
+    courtyard REPLACE_WITH_openssl_rand_hex_32

specs/shorashim_tamid.md

@@ -53,6 +53,15 @@ Rate limit: 10 requests per minute per IP
 
 #### Machaneh Leviyah — Authenticated Endpoint
 
+**The gate.** A key is a line in the keys file
+(`/etc/shorashim/secrets/api_keys`, Construction §4.6 — a file, never an
+environment variable), `tier key`, tier `courtyard` or `chatzer`. The
+key is compared in constant time against every line; a `chatzer` key
+opens the courtyard too, a `courtyard` key at the chatzer is 403. No
+file or no keys: nobody passes, and the log says `GATE_NO_KEYS`. The
+caller is never told why beyond "missing or invalid API key". Issued by
+the kohen (KOHEN.md "Issuing a key"); the key never appears in a log.
+
 ```
 Endpoint: POST /courtyard/offering
 
@@ -94,6 +103,7 @@ Response:
 
 Errors:
   401 — Invalid or missing API key
+  403 — A key for an outer ring at an inner gate
   422 — Input failed kiyor (validation). Body includes purification guidance.
   429 — Rate limit exceeded. Body includes manna explanation.
   503 — System in Shabbat/festival mode. Body includes resumption time.
@@ -162,6 +172,7 @@ Response (200):
 
 Errors:
   401 — Invalid or missing API key
+  403 — A key for an outer ring at an inner gate
   422 — Missing or empty output, output over 65,536 bytes, unknown model
   503 — MANNA_DEPLETED (provision exhausted), KORBAN_UNAVAILABLE,
         TALMUDIC_UNAVAILABLE. Body says which; resubmit: true.

specs/shorashim_vayakhel.md

@@ -629,6 +629,7 @@ table inet filter {
 # /etc/shorashim/secrets/ (mode 0600, owned by shorashim user)
 ├── db_password              # PostgreSQL password
 ├── claude_api_key           # Anthropic API key for korban source
+├── api_keys                 # Courtyard/chatzer keys, one "tier key" per line (Tamid §1.1)
 ├── l1_hash                  # Expected SHA-256 of L1 filesystem
 └── kohanim_ssh_keys/        # Authorized keys for kohanim (operators) SSH
 ```

vav_pipeline/config/config.exs

@@ -17,7 +17,10 @@ config :vav_pipeline,
   shoresh_engine_cwd: nil,
   # Talmudic Engine (Prolog) — Unix domain socket path
   talmudic_socket_path: "/tmp/shorashim/talmudic.sock",
-  korban_socket_path: "/tmp/shorashim/korban.sock"
+  korban_socket_path: "/tmp/shorashim/korban.sock",
+  # Courtyard / chatzer keys (BigdeiKodesh.Gate). nil → the gate is shut.
+  # Construction §4.6: a file, never an environment variable.
+  api_keys_file: nil
 
 # L3 — Oral Tradition (PostgreSQL)
 # Architecture §3.7: Append-only. INSERT allowed. Never UPDATE. Never DELETE.

vav_pipeline/config/runtime.exs

@@ -30,6 +30,8 @@ if config_env() == :prod do
       System.get_env("TALMUDIC_SOCKET_PATH") || "/tmp/shorashim/talmudic.sock",
     korban_socket_path:
       System.get_env("KORBAN_SOCKET_PATH") || "/tmp/shorashim/korban.sock",
+    # The keys themselves are in the file (a mounted Secret), not in env.
+    api_keys_file: System.get_env("API_KEYS_FILE") || "/etc/shorashim/secrets/api_keys",
     # Shoresh Engine binary — VavPipeline.ShoreshEnginePort opens an
     # Erlang Port with {:spawn_executable, binary}, which spawns a CHILD
     # PROCESS OF THIS CONTAINER. A Port cannot cross a container

vav_pipeline/config/test.exs

@@ -6,6 +6,7 @@ config :logger, level: :warning
 config :vav_pipeline,
   l1_mount_point: "../l1",
   manna_provision_file: "test/fixtures/manna/today.json",
+  api_keys_file: "test/fixtures/api_keys",
   cycle_boundary_check_interval_ms: :timer.hours(24),
   http_port: 0
 

vav_pipeline/lib/vav_pipeline/bigdei_kodesh/gate.ex

@@ -0,0 +1,130 @@
+defmodule VavPipeline.BigdeiKodesh.Gate do
+  @moduledoc """
+  The gate of the courtyard — who may bring an offering past the pe'ah.
+
+  Bamidbar 1:51 — *v'hazar hakarev yumat*: the stranger who draws near
+  the inner service does not pass. The pe'ah (`/peah/*`) is open to the
+  ger; the courtyard (`/courtyard/*`) and the chatzer (`/chatzer/*`) are
+  for those who were given a key.
+
+  Until 2026-10-06 the gate looked only at the SHAPE of the header: any
+  `Authorization: Bearer <anything>` was admitted. A gate that opens for
+  every hand is a wall with a hole in it, and every admitted request
+  spends the day's manna.
+
+  **Keys.** A file (Construction §4.6: secrets are files, mode 0600,
+  never environment variables, never configuration, never the
+  repository), one key per line:
+
+      # tier  key
+      courtyard  5f2c…   # may bring offerings and bedikot
+      chatzer    9a1e…   # may also convene the Sanhedrin
+
+  A chatzer key opens the courtyard too — the inner ring contains the
+  outer. Blank lines and `#` comments are ignored. The file is read on
+  every request so that a rotated key takes effect at once; it is a few
+  lines, and the cost is nothing beside a cycle.
+
+  **Fail closed.** No file, an empty file, an unreadable file — nobody
+  passes. The operator sees it in the log (`GATE_NO_KEYS`), never the
+  caller: the caller is told only that the key is missing or invalid.
+
+  Keys are compared in constant time (`Plug.Crypto.secure_compare/2`).
+  No key, valid or not, is ever written to a log.
+  """
+
+  require Logger
+
+  @tiers [:courtyard, :chatzer]
+  @type tier :: :courtyard | :chatzer
+
+  @doc "Tiers, outermost first. A key of a later tier opens every earlier one."
+  @spec tiers() :: [tier()]
+  def tiers, do: @tiers
+
+  @doc "Where the keys are read from. `nil` means the gate is shut."
+  @spec keys_file() :: String.t() | nil
+  def keys_file, do: Application.get_env(:vav_pipeline, :api_keys_file)
+
+  @doc """
+  Admit the request to `tier`, or say why not.
+
+    * `{:ok, granted}` — the key is good for `granted`, which is `tier`
+      or an inner one.
+    * `{:error, :no_header}` — no `Authorization: Bearer <key>` header.
+    * `{:error, :unknown_key}` — the key is not in the file, or there
+      is no file (logged as GATE_NO_KEYS, once per denial).
+    * `{:error, :tier_too_low}` — a good key, but for an outer ring.
+  """
+  @spec admit(Plug.Conn.t(), tier()) ::
+          {:ok, tier()} | {:error, :no_header | :unknown_key | :tier_too_low}
+  def admit(conn, tier) when tier in @tiers do
+    with {:ok, key} <- bearer(conn),
+         {:ok, granted} <- lookup(key, keys_file()) do
+      if rank(granted) >= rank(tier), do: {:ok, granted}, else: {:error, :tier_too_low}
+    end
+  end
+
+  @doc "Parse the contents of a keys file into `[{tier, key}]`. Malformed lines are skipped."
+  @spec parse(String.t()) :: [{tier(), String.t()}]
+  def parse(contents) do
+    contents
+    |> String.split(~r/\r?\n/)
+    |> Enum.map(&String.trim/1)
+    |> Enum.reject(&(&1 == "" or String.starts_with?(&1, "#")))
+    |> Enum.flat_map(fn line ->
+      case String.split(line, ~r/\s+/, parts: 3) do
+        [tier, key | _] when tier in ["courtyard", "chatzer"] and key != "" ->
+          [{String.to_existing_atom(tier), key}]
+
+        _ ->
+          []
+      end
+    end)
+  end
+
+  # ------------------------------------------------------------
+
+  defp bearer(conn) do
+    case Plug.Conn.get_req_header(conn, "authorization") do
+      ["Bearer " <> key] when key != "" -> {:ok, String.trim(key)}
+      _ -> {:error, :no_header}
+    end
+  end
+
+  defp lookup(_key, nil) do
+    Logger.warning("GATE_NO_KEYS: no api_keys_file configured — the courtyard is shut")
+    {:error, :unknown_key}
+  end
+
+  defp lookup(key, path) do
+    case File.read(path) do
+      {:ok, contents} ->
+        entries = parse(contents)
+
+        if entries == [] do
+          Logger.warning("GATE_NO_KEYS: #{path} holds no keys — the courtyard is shut")
+        end
+
+        # Compare against every entry, not just until the first match:
+        # the time taken must not say how far down the file the key was.
+        entries
+        |> Enum.reduce(nil, fn {tier, candidate}, found ->
+          if Plug.Crypto.secure_compare(candidate, key), do: best(found, tier), else: found
+        end)
+        |> case do
+          nil -> {:error, :unknown_key}
+          tier -> {:ok, tier}
+        end
+
+      {:error, reason} ->
+        Logger.warning("GATE_NO_KEYS: cannot read #{path} (#{reason}) — the courtyard is shut")
+        {:error, :unknown_key}
+    end
+  end
+
+  defp best(nil, tier), do: tier
+  defp best(a, b), do: if(rank(a) >= rank(b), do: a, else: b)
+
+  defp rank(tier), do: Enum.find_index(@tiers, &(&1 == tier))
+end

vav_pipeline/lib/vav_pipeline/bigdei_kodesh/router.ex

@@ -28,6 +28,8 @@ defmodule VavPipeline.BigdeiKodesh.Router do
 
   require Logger
 
+  alias VavPipeline.BigdeiKodesh.Gate
+
   # Form 3 architectural enforcement (vehaya §3.2). NoTrackingLogger
   # replaces Plug.Logger; sanitized paths on /peah/* honor the
   # no-tracking promise made in /peah/ask's own response body.
@@ -128,21 +130,35 @@ defmodule VavPipeline.BigdeiKodesh.Router do
   end
 
   # === COURTYARD — Authenticated ===
+  #
+  # The key is checked against the keys file (VavPipeline.BigdeiKodesh.Gate),
+  # not merely for its shape. Until 2026-10-06 any Bearer value passed.
+  defp through_the_gate(conn, tier, serve) do
+    case Gate.admit(conn, tier) do
+      {:ok, _granted} ->
+        serve.(conn)
 
-  post "/courtyard/offering" do
-    case get_req_header(conn, "authorization") do
-      ["Bearer " <> _token] ->
-        process_courtyard(conn)
+      {:error, :tier_too_low} ->
+        send_error(conn, 403, "FORBIDDEN", %{
+          issue: "This key does not open the #{tier}",
+          correction: "Use a key issued for the #{tier} tier",
+          resubmit: false
+        })
 
-      _ ->
+      {:error, _} ->
         send_error(conn, 401, "UNAUTHORIZED", %{
-          issue: "Missing or invalid Authorization header",
-          correction: "Include 'Authorization: Bearer <api-key>' header",
+          issue: "Missing or invalid API key",
+          correction: "Include 'Authorization: Bearer <api-key>' with a key issued by the kohen",
           resubmit: true
         })
     end
   end
 
+
+  post "/courtyard/offering" do
+    through_the_gate(conn, :courtyard, &process_courtyard/1)
+  end
+
   # === COURTYARD — the bedikah (Construction §3.9) ===
   #
   # An external model's output, brought by hand to be examined against
@@ -152,33 +168,13 @@ defmodule VavPipeline.BigdeiKodesh.Router do
   # engraved in L3. See VavPipeline.Bedikah.
 
   post "/courtyard/bedikah" do
-    case get_req_header(conn, "authorization") do
-      ["Bearer " <> _token] ->
-        process_bedikah(conn)
-
-      _ ->
-        send_error(conn, 401, "UNAUTHORIZED", %{
-          issue: "Missing or invalid Authorization header",
-          correction: "Include 'Authorization: Bearer <api-key>' header",
-          resubmit: true
-        })
-    end
+    through_the_gate(conn, :courtyard, &process_bedikah/1)
   end
 
   # === CHATZER — Full Access (Sanhedrin) ===
 
   post "/chatzer/sanhedrin" do
-    case get_req_header(conn, "authorization") do
-      ["Bearer " <> _token] ->
-        process_sanhedrin(conn)
-
-      _ ->
-        send_error(conn, 401, "UNAUTHORIZED", %{
-          issue: "Missing or invalid Authorization header",
-          correction: "Include 'Authorization: Bearer <api-key>' header",
-          resubmit: true
-        })
-    end
+    through_the_gate(conn, :chatzer, &process_sanhedrin/1)
   end
 
   # === KODESH — Operator Interface ===
@@ -954,6 +950,7 @@ defmodule VavPipeline.BigdeiKodesh.Router do
   defp error_type("CLOUD" <> _), do: "system_transition"
   defp error_type("HALT" <> _), do: "cardinal_sin_detected"
   defp error_type("UNAUTHORIZED"), do: "authentication_required"
+  defp error_type("FORBIDDEN"), do: "insufficient_tier"
   defp error_type("TEIKU" <> _), do: "unresolvable"
   defp error_type("LO_TOV"), do: "specification_mismatch"
   defp error_type("CHATAT" <> _), do: "correction_needed"

vav_pipeline/lib/vav_pipeline/doorpost.ex

@@ -175,7 +175,7 @@ defmodule VavPipeline.Doorpost do
   # changes; the update is a deliberate operator commit. A bare
   # hash-update commit (without a corresponding spec change in the
   # same commit) is itself a drift signal.
-  @expected_hash "91d09d8dfb47f4440e5e02f8ef2695026fade315cfaadf7c72c126bad3903547"
+  @expected_hash "42b38626c6e2bd3e6fe10ed7f4cb34ee8dae118205379b7d822f278fe7eaa110"
 
   @doc "Return the list of files that constitute the category-grade specification."
   @spec files() :: [String.t()]

vav_pipeline/test/bedikah_test.exs

@@ -342,7 +342,7 @@ defmodule VavPipeline.BedikahTest do
 
   defp post_bedikah(body, opts \\ []) do
     conn = conn(:post, "/courtyard/bedikah", Jason.encode!(body)) |> put_req_header("content-type", "application/json")
-    conn = if Keyword.get(opts, :auth, true), do: put_req_header(conn, "authorization", "Bearer test"), else: conn
+    conn = if Keyword.get(opts, :auth, true), do: put_req_header(conn, "authorization", "Bearer test-token"), else: conn
     Router.call(conn, @opts)
   end
 

vav_pipeline/test/bigdei_kodesh_test.exs

@@ -294,7 +294,7 @@ defmodule VavPipeline.BigdeiKodeshTest do
       conn =
         conn(:post, "/chatzer/sanhedrin", Jason.encode!(%{not_case: "wrong field"}))
         |> put_req_header("content-type", "application/json")
-        |> put_req_header("authorization", "Bearer test-token")
+        |> put_req_header("authorization", "Bearer chatzer-test-token")
         |> Router.call(@opts)
 
       assert conn.status == 422
@@ -306,7 +306,7 @@ defmodule VavPipeline.BigdeiKodeshTest do
           case: "Is cooking on Shabbat permitted for pikuach nefesh?"
         }))
         |> put_req_header("content-type", "application/json")
-        |> put_req_header("authorization", "Bearer test-token")
+        |> put_req_header("authorization", "Bearer chatzer-test-token")
         |> Router.call(@opts)
 
       assert conn.status == 200

vav_pipeline/test/fixtures/api_keys

@@ -0,0 +1,6 @@
+# Test keys for the gate (BigdeiKodesh.Gate). tier, whitespace, key.
+courtyard  test-token
+chatzer    chatzer-test-token
+
+# A malformed line, ignored:
+kodesh     not-a-tier

vav_pipeline/test/fixtures/manna/ledger.json

@@ -0,0 +1 @@
+{"consumed":{"api_calls_external":0,"compute_units":3,"memory_mb":0,"sanhedrin_panels_max":0,"storage_delta_mb":0},"cycle_date":"2026-10-06","written_at":"2026-10-06T15:15:24.042079Z"}

vav_pipeline/test/tablet45_gate_test.exs

@@ -0,0 +1,113 @@
+defmodule VavPipeline.Tablet45GateTest do
+  @moduledoc """
+  Tablet 45 (2026-10-06) — the courtyard gate opened for any hand.
+
+  `/courtyard/*` and `/chatzer/*` checked that the Authorization header
+  had the SHAPE `Bearer <something>`, and nothing else. Every test of it
+  sent `Bearer test-token` and passed; none sent `Bearer wrong`.
+
+  These tests send the wrong key, no key, a key for the outer ring at
+  the inner gate, and a key when there is no keys file at all.
+  """
+
+  use ExUnit.Case, async: false
+
+  import Plug.Test
+  import Plug.Conn
+
+  alias VavPipeline.BigdeiKodesh.{Gate, Router}
+
+  @opts Router.init([])
+
+  describe "Gate.parse/1" do
+    test "reads tier and key, skips comments, blanks and unknown tiers" do
+      assert Gate.parse("""
+             # keys
+             courtyard  abc
+
+             chatzer\tdef   # trailing words are ignored
+             kodesh     ghi
+             courtyard
+             """) == [courtyard: "abc", chatzer: "def"]
+    end
+  end
+
+  describe "Gate.admit/2" do
+    test "the right key for the ring" do
+      assert {:ok, :courtyard} = Gate.admit(with_key("test-token"), :courtyard)
+      assert {:ok, :chatzer} = Gate.admit(with_key("chatzer-test-token"), :chatzer)
+    end
+
+    test "the inner ring's key opens the outer gate; not the reverse" do
+      assert {:ok, :chatzer} = Gate.admit(with_key("chatzer-test-token"), :courtyard)
+      assert {:error, :tier_too_low} = Gate.admit(with_key("test-token"), :chatzer)
+    end
+
+    test "a wrong key, a near key, an empty key, no header" do
+      assert {:error, :unknown_key} = Gate.admit(with_key("wrong"), :courtyard)
+      assert {:error, :unknown_key} = Gate.admit(with_key("test-token2"), :courtyard)
+      assert {:error, :unknown_key} = Gate.admit(with_key("test-toke"), :courtyard)
+      assert {:error, :no_header} = Gate.admit(with_key(""), :courtyard)
+      assert {:error, :no_header} = Gate.admit(conn(:post, "/courtyard/offering"), :courtyard)
+
+      basic = conn(:post, "/courtyard/offering") |> put_req_header("authorization", "Basic dGVzdA==")
+      assert {:error, :no_header} = Gate.admit(basic, :courtyard)
+    end
+
+    test "no keys file, an empty one, a missing one — nobody passes" do
+      original = Application.get_env(:vav_pipeline, :api_keys_file)
+      on_exit(fn -> Application.put_env(:vav_pipeline, :api_keys_file, original) end)
+
+      Application.put_env(:vav_pipeline, :api_keys_file, nil)
+      assert {:error, :unknown_key} = Gate.admit(with_key("test-token"), :courtyard)
+
+      empty = Path.join(System.tmp_dir!(), "tablet45_empty_#{System.unique_integer([:positive])}")
+      File.write!(empty, "# nothing here\n\n")
+      Application.put_env(:vav_pipeline, :api_keys_file, empty)
+      assert {:error, :unknown_key} = Gate.admit(with_key("test-token"), :courtyard)
+      File.rm!(empty)
+
+      Application.put_env(:vav_pipeline, :api_keys_file, "/nonexistent/api_keys")
+      assert {:error, :unknown_key} = Gate.admit(with_key("test-token"), :courtyard)
+    end
+  end
+
+  describe "at the router" do
+    test "a wrong key is 401 at every gated door, and says nothing about the keys" do
+      for {path, body} <- [
+            {"/courtyard/offering", %{offering_type: "shelamim", content: "x"}},
+            {"/courtyard/bedikah", %{output: "x", model: "gpt"}},
+            {"/chatzer/sanhedrin", %{case: "x"}}
+          ] do
+        conn = post(path, body, "Bearer wrong")
+        assert conn.status == 401, path
+        decoded = Jason.decode!(conn.resp_body)
+        assert decoded["error"]["code"] == "UNAUTHORIZED"
+        refute conn.resp_body =~ "test-token"
+      end
+    end
+
+    test "a courtyard key at the chatzer is 403, not 401" do
+      conn = post("/chatzer/sanhedrin", %{case: "x"}, "Bearer test-token")
+      assert conn.status == 403
+      assert Jason.decode!(conn.resp_body)["error"]["code"] == "FORBIDDEN"
+    end
+
+    test "a chatzer key is good in the courtyard" do
+      conn = post("/courtyard/offering", %{offering_type: "shelamim"}, "Bearer chatzer-test-token")
+      # Past the gate: the next check (no content) answers, not the gate.
+      assert conn.status == 422
+    end
+  end
+
+  defp with_key(key) do
+    conn(:post, "/courtyard/offering") |> put_req_header("authorization", "Bearer " <> key)
+  end
+
+  defp post(path, body, auth) do
+    conn(:post, path, Jason.encode!(body))
+    |> put_req_header("content-type", "application/json")
+    |> put_req_header("authorization", auth)
+    |> Router.call(@opts)
+  end
+end