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).

src/agent/tools.ts

@@ -4,6 +4,7 @@ import { questionResult, serverExecute, ToolInputError } from "./tool-execute.ts
 import {
 	askInputSchema,
 	askOptionProblems,
+	parseOptionsIfString,
 	probeQuizInputSchema,
 	quizInputObject,
 	quizInputProblems,
@@ -51,6 +52,26 @@ export type { ProbeDoneContext } from "./tools/probe.ts";
  *   only.
  */
 
+/** GLM wobble guard (owner-approved, 2026-09-26): models sometimes emit
+ *  `options` as a JSON-encoded string instead of an array; pi runs this
+ *  BEFORE schema validation, so a double-encoded call lands instead of
+ *  bouncing back as a validation error + wasted retry turn. NOTE: pi
+ *  persists the tool call with its RAW arguments — the client coerces
+ *  again in normalizeOptions (question-core), the same parseOptionsIfString.
+ *  Anything unparseable passes through untouched: validation then reports
+ *  honestly and the agent retries with a real error to learn from. */
+function prepareQuestionArguments<T extends object>(args: unknown): T {
+	if (args && typeof args === "object" && !Array.isArray(args)) {
+		const o = args as { options?: unknown };
+		if (typeof o.options === "string") {
+			const parsed = parseOptionsIfString(o.options);
+			if (parsed !== o.options) return { ...o, options: parsed } as T;
+		}
+		return o as T;
+	}
+	return args as T;
+}
+
 export const askUserQuestionTool: AgentTool<typeof askInputSchema> = {
 	name: "ask_user_question",
 	label: "ask_user_question",
@@ -60,6 +81,7 @@ export const askUserQuestionTool: AgentTool<typeof askInputSchema> = {
 		"or you need an open-ended response. ONE question per turn: call a single ask_user_question, then end your " +
 		"turn — his answer determines the next.",
 	parameters: askInputSchema,
+	prepareArguments: prepareQuestionArguments,
 	executionMode: "sequential",
 	execute: async (_toolCallId, input) => {
 		const problems = askOptionProblems(input.options ?? []);
@@ -85,6 +107,7 @@ export const probeQuizTool: AgentTool<typeof probeQuizInputSchema> = {
 		"questions use ask_user_question instead. ONE question per turn: call a single quiz, then end your turn — " +
 		"his answer determines the next question to ask.",
 	parameters: probeQuizInputSchema,
+	prepareArguments: prepareQuestionArguments,
 	executionMode: "sequential",
 	execute: async (_toolCallId, input) => {
 		const problems = quizInputProblems(input);
@@ -206,6 +229,7 @@ export function teachQuizToolFor(ctx: Pick<PlanToolContext, "chatId" | "chatStor
 			"only when non-empty. No free-text answers — for non-graded questions use ask_user_question instead. " +
 			"ONE question per turn: call a single quiz, then end your turn — his answer determines the next.",
 		parameters: quizInputObject,
+		prepareArguments: prepareQuestionArguments,
 		executionMode: "sequential",
 		execute: async (_toolCallId, input) => {
 			const problems = [...quizInputProblems(input)];