tablet 55: the row that was a label — the Sanhedrin's example request crashed its own gate

Verified live 2026-10-19: Tamid's own example for POST /chatzer/sanhedrin
(a case with `sides`) answered 500. The router passed the sides LIST as
the case context; halt_monitor:check_avodah_zarah/1 reads a map, maps:get
raised, and the halt monitor and escalation gen_servers died with the
caller's input (supervisor restarted them; health stayed 8/8). The router
then matched {:ok, decision} on the error and made a 500 of its own.

- sanhedrin/src/halt_monitor.erl: do_check_case refuses a non-map
  context as {halt, malformed_case, _} and stays standing. EUnit 49/0
  with the new halt_malformed_context_test.
- router.ex process_sanhedrin: sides validated at the kiyor (422 on a bad
  shape), carried as context %{sides: sides}; a Sanhedrin refusal answers
  422 SANHEDRIN_HALTED, a failure 503 SANHEDRIN_UNAVAILABLE. Two new
  router tests, one asserting the gate processes survive the example.
  Elixir 624/0.
- specs/broken_tablets/README.md: tablet 55, including what is NOT fixed
  — a panel of one accepting on zero references under a grounded-
  sounding sentence, the ignored complexity hint, no panel manna spent,
  no L3 record. The row in Tamid is still larger than the thing behind it.

Doorpost pin unchanged (no @spec_files touched; scripts/doorpost_check.py
passes).

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

specs/broken_tablets/README.md

@@ -132,3 +132,49 @@ make. The fence held throughout — each forgery was stripped and named by
 a verdict the builder did not write — which is the design proving itself
 on its builder: the check has to stand outside the model, because the
 model's own intention is subject to the same pull it is meant to catch.
+
+## Tablet 55 — the row that was a label (2026-10-19)
+
+Tamid promises `POST /chatzer/sanhedrin`: a case, optional sides, a
+panel of three, a majority of two and a minority of one with their
+sources. The row had stood since the endpoint was written. The build
+state carried a line beside it — "never verified on prod" — for months.
+On 2026-10-19 the builder sent the spec's own example request to the
+live system, as the roadmap's rule asks: a spec row is a claim to test,
+not a label.
+
+The first request answered 500. The router had handed the `sides` list
+to the Sanhedrin as the case's *context*, where the halt monitor reads a
+map of `authority_source` and `action`; `maps:get` raised, and the halt
+monitor and the escalation server died with the caller's input. The
+supervisor restarted them; health stayed 8/8 the whole time. A gate that
+can be felled by what it is handed is not a gate, and a health check
+that cannot see the gate fall is not watching it. The router then
+pattern-matched `{:ok, decision}` on an error and turned the refusal
+into a 500 of its own.
+
+The second request, without sides, answered 200 — and the answer was
+hollow. A panel of one, not three. Field names the spec does not use.
+An outcome of "accepted" on zero roots and zero references examined,
+under the sentence "Torah references ground this interpretation". That
+is the shape the bedikah names golden_calf when a model says it: a
+confident claim standing on nothing. Here the system said it in its own
+voice, through its own inner court. The complexity hint was ignored, no
+panel manna was spent, and nothing was engraved in L3.
+
+Fixed in this tablet: the halt monitor refuses a non-map context as
+`malformed_case` and stays standing; the router carries the sides inside
+the context map, checks their shape at the kiyor (422), and answers a
+Sanhedrin refusal (422 SANHEDRIN_HALTED) or failure (503
+SANHEDRIN_UNAVAILABLE) instead of crashing. The spec's own example now
+deliberates, and the test asserts that the gate is still there
+afterwards.
+
+Not fixed, and recorded here so it is not mistaken for fixed: the
+panel of one, the empty references under a grounded-sounding sentence,
+the ignored hint, the unspent manna, the unrecorded case. The row in
+Tamid is still larger than the thing behind it. The lesson is tablet
+37's again — a spec row is a claim to test — with one thing added: the
+system's own inner court is held to the same check as a model at the
+gate. When the Sanhedrin accepts on nothing, it is the calf, whoever
+cast it.