compaction: the surface — settings row, two ruled dividers, summary dialog, send gate (round 14 slice 3)

- settings: compaction.thresholdTokens row on the Agent tab (owner pick)
  in a Context group — CommitInput mirroring the graph budget row, hint
  resolved through the SAME core resolver the trigger reads; PUT rejects
  below the 32k floor with the anti-churn rationale; own section
  (compaction) in SETTINGS_SECTIONS + the settings-signal union
- view fold: one marker → two dividers — the minimal MOMENT divider at
  the marker (retrying-message register, no rule lines) and the longer
  CUT divider emitted immediately before the first kept message
  (phase-divider geometry, chip carries '· Nk tok'); both carry the full
  summary payload; full history stays visible to the user
- components/compaction-divider.tsx: the dividers + summary dialog
  (pure exported body for SSR pins, the delete-dialog pattern; Esc +
  Close dismiss, backdrop does not)
- chat.tsx: compaction-changed SSE flips the running state — composer
  canSend, onSend/doSend/doSteerOrSend, and both docks' submit + hint
  ('compacting session…') gate on it (the server's registry mutex is the
  structural gate; this is the affordance); dialog mounts beside the
  abort dialog
- pins: settings-body (4), view fold (2), divider SSR (4)

tests/compaction.test.ts

@@ -16,6 +16,7 @@ import {
 	type LhMarkerMessage,
 } from "../src/core/index.ts";
 import type { AssistantMessage, ToolResultMessage } from "@earendil-works/pi-ai";
+import { projectView } from "../src/core/view.ts";
 
 /**
  * COMPACTION (owner round 14, 2026-10-05) — the pure core: the cut walk,
@@ -242,3 +243,43 @@ describe("serializeForSummary + buildCompactionPrompt", () => {
 		assert.ok(text.includes("Alpha → Beta"));
 	});
 });
+
+// ---------------------------------------------------------------------------
+// THE VIEW FOLD (owner round 14): two dividers from one marker —
+// the minimal moment divider where the user is, the longer cut divider
+// at the kept boundary. Both carry the full summary payload.
+// ---------------------------------------------------------------------------
+describe("projectView compaction dividers", () => {
+	const record = (): LhMessage[] => [
+		{ id: "old1", role: "user", content: "earliest", timestamp: 1 },
+		{ id: "kept", role: "user", content: "recent", timestamp: 2 },
+		newCompactionMarker("SUMMARY TEXT", {
+			firstKeptMessageId: "kept",
+			tokensBefore: 12345,
+			at: new Date(0).toISOString(),
+		}) as unknown as LhMessage,
+	];
+
+	it("emits the cut divider BEFORE the first kept message", () => {
+		const view = projectView(record());
+		const idx = view.findIndex((m) => m.parts.some((p) => p.type === "data-compaction-cut"));
+		const keptIdx = view.findIndex((m) => m.parts.some((p) => p.type === "text" && p.text === "recent"));
+		assert.ok(idx !== -1, "the cut divider exists");
+		assert.ok(keptIdx !== -1);
+		assert.equal(idx, keptIdx - 1, "immediately before the kept message");
+		const part = view[idx]!.parts.find((p) => p.type === "data-compaction-cut")!;
+		assert.equal((part.data as { content: string }).content.includes("SUMMARY TEXT"), true);
+	});
+
+	it("emits the moment divider at the marker (the transcript tail)", () => {
+		const view = projectView(record());
+		const moment = view.find((m) => m.parts.some((p) => p.type === "data-compaction"));
+		assert.ok(moment, "the moment divider exists");
+		const part = moment!.parts.find((p) => p.type === "data-compaction")!;
+		assert.equal((part.data as { details: { tokensBefore: number } }).details.tokensBefore, 12345);
+		// and it renders AFTER the kept message (the compaction moment is
+		// the tail — where the user is when it happens)
+		const keptIdx = view.findIndex((m) => m.parts.some((p) => p.type === "text" && p.text === "recent"));
+		assert.ok(view.indexOf(moment!) > keptIdx);
+	});
+});