fix: quiet Retrying lines, quiz option descriptions nuked, dividers at the markers

Three owner rulings from the gradient-descent session
(chat_muhskq6p_e8c3600b — 7 failed quiz calls, answers leaked in
option descriptions, planning divider floating at the transcript top):

1. RETRYING LINES (general): any tool call that errors back to the
   agent (validation failure, malformed args — the retry loop) renders
   one quiet "Retrying…" SystemLine instead of silence. Question tools
   previously rendered null, so a flailing quiz loop read as a stall.
   Aborts are terminal ("Operation aborted") and stay silent. Verified
   live: exactly 7 lines render at the 7 failure sites of the session.

2. QUIZ OPTION DESCRIPTIONS: NUKED. The model used them to telegraph
   correctness in every quiz of the session ("that moves uphill — it
   climbs f instead of descending it") — answerable by elimination.
   The field is gone from BOTH quiz schemas (probe + teach); ask keeps
   it (ungraded — nothing to leak). The dock additionally suppresses
   descriptions for quiz kind, so pre-fix records stop leaking too.
   Verified live: the session's pending quiz renders bare labels.

   Plus the diagnosed failure-mode fixes: GLM sometimes emits `options`
   as a JSON-encoded string (6 of 7 failures). prepareArguments hooks
   on all three question tools coerce it BEFORE pi's validation (the
   call lands instead of bouncing); the client coerces again in
   normalizeOptions (pi persists raw call args). Schema descriptions
   hardened ("REQUIRED ... never a JSON-encoded string").

3. DIVIDERS AT THE MARKERS: the probe-handoff SystemLine
   ("Preparing your plan…") IS NOW the Planning divider; the accepted
   verdict IS NOW the Teaching divider ("✓ Plan accepted" line gone) —
   one signal per seam, not two. The fold-based divider block is
   DELETED: Wave D grouping merged the whole probe into one giant
   assistant group, so the inclusive-fold comparison floated the
   divider to the transcript top (reproduced against the real record:
   6 view messages, phase flipped at the giant group). The markers
   render in the right spot by record construction. A DECLINED verdict
   is not a seam — it keeps the "↻ Plan revision requested" line.
   Verified live: plan divider after the probe concluded, teach
   divider after the plan presentation, nothing at the top.

Tests: 1004/1004 — string-coercion pins (normalizeOptions + the
prepareArguments hooks on all three tools, identity fast path),
quiz-schema-has-no-description pin (ask keeps it).

components/question-dock.tsx

@@ -457,9 +457,12 @@ function QuestionDockForm({
 									</span>
 									<span>
 										<MessageResponse>{opt.label}</MessageResponse>
-										{opt.description && (
+										{kind !== "quiz" && opt.description && (
 											// Option subtext renders in Source Sans 3 (owner's mockup);
-											// the "I don't know" copy stays JetBrains Mono.
+											// the "I don't know" copy stays JetBrains Mono. QUIZ options render
+											// NO description (owner ruling 2026-09-26): the model used them to
+											// telegraph correctness — the schema dropped the field and old
+											// records must not leak either.
 											<span className="lh-prose block text-xs text-muted-foreground">{opt.description}</span>
 										)}
 									</span>