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/jobs.test.ts

@@ -238,14 +238,19 @@ describe("steer helpers (contracts.ts)", () => {
 		}, "lastStep always mirrors the LATEST call, never the sums");
 	});
 
-	it("buildAbortSteer: metadata-aborted, text-only (no artifact), same deterministic id space as the result steer", () => {
+	it("buildAbortSteer: teacher-facing text + the data-subagent-aborted marker part (the message type), same deterministic id space as the result steer", () => {
 		const steer = buildAbortSteer({ id: "job_c", kind: "demo", toolCallId: "call-c" });
 		assert.equal(steer.id, "steer_job_c", "same id space — steerDelivered treats either as delivered");
 		assert.equal(steer.role, "user");
 		assert.equal(steer.metadata.subagentResult.aborted, true);
 		assert.equal(steer.metadata.subagentResult.jobId, "job_c");
-		assert.equal(steer.parts.length, 1);
+		assert.equal(steer.parts.length, 2);
 		assert.ok(steer.parts[0]!.type === "text" && /aborted/.test(steer.parts[0].text));
+		// The marker PART is the message type (the custom-message scheme): the
+		// UI renders the abort badge off it — metadata stays for pump mechanics.
+		const marker = steer.parts[1]!;
+		assert.equal(marker.type, "data-subagent-aborted");
+		assert.deepEqual(marker.data, { jobId: "job_c", kind: "demo", toolCallId: "call-c", aborted: true });
 	});
 
 	it("isSubagentFailure: failure shapes only (empty html/svg, failure brief)", () => {
@@ -996,7 +1001,8 @@ describe("abort (src/server/jobs.ts abortJob)", () => {
 			const last = fired[0]!;
 			assert.equal((last.metadata as { subagentResult: { aborted: boolean } }).subagentResult.aborted, true);
 			assert.equal(last.id, `steer_${jobId}`);
-			assert.equal(last.parts.length, 1, "text only — no artifact part");
+			assert.equal(last.parts.length, 2, "teacher-facing text + the data-subagent-aborted marker part — no artifact");
+			assert.equal(last.parts[1]!.type, "data-subagent-aborted");
 			// aborted is terminal: the wake completing must not flip it
 			assert.equal(jobStore.getJob(jobId)!.status, "error", "terminal after the wake");
 		} finally {