tools: the standard argument heal — every registry, both seams

The whitehead incident (2026-10-09): glm-5.3 emitted quiz type with
quotes baked in ('"predict"') — rejected ten times, byte-identical
retries, the lesson never started — and correctAnswer with the JSON
key-value colon glued on ([':parmenides']). Third GLM wobble incident,
and each prior heal was wired only where its incident landed; this one
landed precisely where the practice heal never reached.

Layer 1 — healEncodedArguments moves to core/argument-heal (the display
seam needs it too — the tool-parts law) with withArgumentHeal +
healToolRecord (agent/tools/heal) wired at EVERY registry: prober,
teacher, practice, bareQuestionTools (it had no prepareArguments at
all), demo-builder, and submit-agent (composing after
healStringifiedArrays; the auditor's extraTools wrapped).

Layer 2 — stripModelValueDebris (core/value-debris): leading/trailing
colons, quotes, backticks, whitespace strip at the MEMBERSHIP seams —
coerceCorrectAnswer (boundary check + display + grading in one),
normalizeQuizType (persisted wobbled records keep their role),
resolveTargetId (copy-syntax on targets).

Layer 3 — schema description hygiene: the quiz type and practice
mode/outcome/rung/missClass values now read as bare words — the quoted
JSON-key style invited quote-copying.

Display mirror — parseQuizInput heals the raw record on read, so a
boundary-healed quiz whose record keeps raw args renders instead of
becoming an invisible pending quiz (learner lockout).

Pins: tests/tool-heal.test.ts (the incident shapes end-to-end through
pi-ai validation, the wiring, the strips, the mirror). The stringy-
options pins flip to boundary-parity per tool-parts' own law; the
chat-flow garbage pin keeps its honest-reject intent with an unhealable
shape. 1471 tests, typecheck, lint green.

src/agent/subagents/demo-builder.ts

@@ -6,6 +6,7 @@ import type { PiEngine } from "../models.ts";
 import { runSubagent } from "./pi-run.ts";
 import type { DemoResult } from "../../core/contracts.ts";
 import { getHeadless, type DemoRunResult, type HeadlessApi } from "./headless.ts";
+import { healToolRecord } from "../tools/heal.ts";
 
 /**
  * The demo-builder sub-agent (vision §2 interactive demos + §2.5 "sub-agents
@@ -99,7 +100,7 @@ export function createDemoBuilderTools(
 	headless: HeadlessApi,
 	onActivity?: (line: string) => void,
 ): Record<string, AgentTool<any>> {
-	return {
+	return healToolRecord({
 		write_demo: {
 			name: "write_demo",
 			label: "write_demo",
@@ -141,7 +142,7 @@ export function createDemoBuilderTools(
 				return formatRunResult(result);
 			}),
 		},
-	};
+	});
 }
 
 function summarizeCounts(result: DemoRunResult): string {