Phase 14: defer reinject plan without registry at compaction — B-002 stage 1

planDeferredReinject locks pending by kept-window only; defer path in index uses it while immediate keeps registered filter at compact time.

Co-authored-by: Cursor <cursoragent@cursor.com>

test/b002-repro-pre-fix.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { planReinject } from "../src/reinject.js";
+import { planDeferredReinject, planReinject } from "../src/reinject.js";
 import { createDefaultSettings } from "../src/settings.js";
 import { createInitialState, trackSkill } from "../src/state.js";
 
@@ -67,4 +67,32 @@ describe("B-002 pre-fix filter hypothesis", () => {
 
 		expect(planned).toEqual([]);
 	});
+
+	it("defer plan includes skill absent from kept even when registered is empty", () => {
+		const state = createInitialState();
+		trackSkill(state, {
+			name: "fup-blame-commits",
+			filePath: "/home/user/.cursor/skills/fup-blame-commits/SKILL.md",
+			baseDir: "/home/user/.cursor/skills/fup-blame-commits",
+			source: "skill-block",
+		});
+
+		const branch = [
+			{
+				id: "keep-1",
+				type: "message",
+				message: { role: "user", content: "plain text after compact" },
+			},
+		] as never;
+
+		const planned = planDeferredReinject(
+			state,
+			{
+				sessionManager: { getBranch: () => branch },
+			} as never,
+			{ compactionEntry: { firstKeptEntryId: "keep-1" } } as never,
+		);
+
+		expect(planned).toEqual(["fup-blame-commits"]);
+	});
 });