feat: custom message types for system turns — wake and verdict messages

The custom-message scheme (user-decided 2026-09-12): system-authored
user-role messages are NOT human messages — they carry marker data parts
only, the adapter owns their model-facing wording, and the UI renders
them under control. Nothing fake is ever persisted as human speech.

The inventory (all migrated):
- probe→teacher handoff wake: was a text-bearing user message rendering
  as a fake user bubble; now data-probe-handoff marker-only — the
  adapter flattens it to HANDOFF_TEXT (core/contracts/chat.ts), the UI
  renders a quiet 'Preparing your plan…' system line.
- plan accept/decline: was boilerplate text ('The plan is accepted…',
  'I'd like the plan revised…') masquerading as learner speech — the
  decline wasn't even marked; now data-verdict {accepted, at} on its own
  message, adapter flattens to verdictText(), UI renders the quiet
  verdict marker ('✓ Plan accepted' / '↻ Plan revision requested').
  sendVerdict sends TWO REAL MESSAGES when the learner typed a note
  (the note as a genuine user message, then the verdict) in ONE turn
  via setMessages + sendMessage() — no 409 dance, no double teacher turn.
- sub-agent steers: the abort steer gains its data-subagent-aborted
  marker part; the UI keys steer rendering off PARTS (artifact/aborted),
  not metadata — metadata stays as pump mechanics only.
- record-adapter: systemTextOf() flattens marker-only messages; steers
  keep their text (payload — briefs are content, not boilerplate).

phases.ts: plan→teach advances on data-verdict{accepted:true} only;
learner text alone can never sanction teaching (pinned). data-plan-
accepted retired, no back-compat (user-decided: wiped-data doctrine).

Pinned: record-adapter.test.ts (verdict/handoff flattening, note+verdict
order, steer payload kept, UI-only parts skipped), phases.test.ts
(verdict marker semantics, out-of-order, text-never-fakes), jobs.test.ts
(abort marker part), demos.test.tsx (badge renders off the part, not
metadata).

Live GLM smoke (disposable driver, deleted): probe→conclude→wake→plan→
decline-with-note (revised, still plan)→accept-with-note (teach) — ALL
CHECKS PASS, including marker-only handoff/verdict on the wire and zero
fake human speech in the transcript.

Gates: tsc, lint, build, 335/335.

tests/phases.test.ts

@@ -2,7 +2,7 @@
  * phases — the event-driven phase chain (docs/probe-teach-split.md §4).
  *
  * probe ends at the first CONCLUDED probe_done (output-available); planning
- * ends at the LEARNER'S plan acceptance (a data-plan-accepted part on the
+ * ends at the LEARNER'S plan acceptance (a data-verdict part with accepted:true
  * accept button's user message — plan_init only PRESENTS the map). No
  * stored-tree seam: the phase is a pure fold over the transcript, so it can
  * never stick (the old currentNodeId-based phaseOfTree read a field nothing
@@ -34,18 +34,24 @@ function assistantTool(
 const DONE_ASSESSMENT = { assessment: { strands: [{ strand: "s", assessment: "a" }] } };
 const PLAN_OK = { ok: true, tree: { nodes: [{ id: "n1", title: "N" }], edges: [] } };
 
-/** The accept button's user message (text + marker data part). */
-function planAccepted(): UIMessage {
+/** The verdict button's user message (the custom-message scheme): its own
+ *  message carrying ONLY the data-verdict marker part — no human-authored
+ *  text; the model-facing wording is the adapter's (record-adapter.ts). */
+function verdict(accepted: boolean): UIMessage {
 	return {
-		id: `u_accept_${Math.random().toString(36).slice(2, 6)}`,
+		id: `u_verdict_${Math.random().toString(36).slice(2, 6)}`,
 		role: "user",
 		parts: [
-			{ type: "text", text: "The plan is accepted — begin teaching." },
-			{ type: "data-plan-accepted", id: "pa_1", data: { at: "2026-09-11T00:00:00Z" } } as never,
+			{ type: "data-verdict", id: "vd_1", data: { accepted, at: "2026-09-12T00:00:00Z" } } as never,
 		],
 	};
 }
 
+/** The accept button's message. */
+function planAccepted(): UIMessage {
+	return verdict(true);
+}
+
 test("phaseAt3: probe until a concluded probe_done; plan until the learner ACCEPTS; teach after", () => {
 	const probe = phaseAt3([user("teach me calculus"), assistantTool("quiz", "output-available")]);
 	assert.equal(probe, "probe", "quiz answers alone never end the probe");
@@ -75,10 +81,10 @@ test("phaseAt3: probe until a concluded probe_done; plan until the learner ACCEP
 		user("teach me"),
 		assistantTool("probe_done", "output-available", DONE_ASSESSMENT),
 		assistantTool("plan_init", "output-available", PLAN_OK),
-		user("revise it"),
+		verdict(false),
 		assistantTool("plan_init", "output-available", PLAN_OK),
 	]);
-	assert.equal(declined, "plan", "a declined plan stays in planning until a later acceptance");
+	assert.equal(declined, "plan", "a DECLINED verdict is a real event but stays in planning until a later acceptance");
 
 	const failedPlan = phaseAt3([
 		user("teach me"),
@@ -89,6 +95,22 @@ test("phaseAt3: probe until a concluded probe_done; plan until the learner ACCEP
 	assert.equal(failedPlan, "teach", "acceptance sanctions teaching even after a failed init attempt — the verdict is his");
 });
 
+test("phaseAt3: the verdict marker is explicit — anonymous learner text never sanctions teaching", () => {
+	const plainText = phaseAt3([
+		user("teach me"),
+		assistantTool("probe_done", "output-available", DONE_ASSESSMENT),
+		assistantTool("plan_init", "output-available", PLAN_OK),
+		user("The plan is accepted — begin teaching."), // words alone, no marker
+	]);
+	assert.equal(plainText, "plan", "only the data-verdict part is the seam — text can never fake it");
+
+	const acceptOutOfOrder = phaseAt3([
+		user("teach me"),
+		verdict(true), // before any probe_done: out of order, advances nothing
+	]);
+	assert.equal(acceptOutOfOrder, "probe", "the chain never skips");
+});
+
 test("phaseAt3: a mere probe_done CALL (input-available, not yet concluded) keeps the probe open", () => {
 	const still = phaseAt3([user("teach me"), assistantTool("probe_done", "input-available")]);
 	assert.equal(still, "probe");