fix(mag): briefing queues /compact after feedback-digest (task-304a02a6)

Swap order in magBriefing() so the on-disk queue becomes
briefing → feedback-digest → /compact. /compact had been wiping the
briefing context before feedback-digest could read it; now /compact
lands last so digest sees prior context and the next session starts
fresh. Comment block above /compact rewritten to drop the now-false
"directly behind" rationale; task-a00fc0d9 reference preserved.

Test renamed to assert the new invariant (last item is /compact,
middle item is feedback-digest in clean state) and a sibling test
covers the gated branch (length 2 with /compact still last).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: lukstafi

src/mag-auto-compact.test.ts

@@ -1,5 +1,5 @@
 import { afterEach, beforeEach, describe, expect, test } from "bun:test";
-import { mkdirSync, readFileSync } from "fs";
+import { mkdirSync, readFileSync, writeFileSync } from "fs";
 import { join } from "path";
 import { withSyntheticHarness } from "./test-utils.ts";
 
@@ -27,16 +27,49 @@ function readQueue(): Record<string, unknown>[] {
 }
 
 describe("magBriefing auto-compact follow-up", () => {
-  test("enqueues /compact directly behind the briefing entry", async () => {
+  test("enqueues /compact as the final item, with feedback-digest between briefing and /compact", async () => {
+    // Harness condition: clean state — no pre-existing pending feedback-digest
+    // in queue.jsonl, no cooldown state file. The synthetic harness creates a
+    // fresh tmp dir each test, so both gates open and tryQueueFeedbackDigest
+    // actually enqueues. If that condition stops holding, items[1] would not be
+    // "feedback-digest" and the middle-slot assertion would fail loudly.
     const { magBriefing } = await import("./mag.ts");
     magBriefing(false);
 
     const items = readQueue();
-    // Must be at least: briefing, /compact (feedback-digest may follow).
-    expect(items.length).toBeGreaterThanOrEqual(2);
+    // briefing → feedback-digest → /compact. /compact must always land last
+    // (the AC's invariant); feedback-digest in the middle is the ungated path.
+    expect(items).toHaveLength(3);
     expect(items[0]!.action).toBe("briefing");
-    expect(items[1]!.action).toBe("message");
-    expect(items[1]!.content).toBe("/compact");
+    expect(items[1]!.action).toBe("feedback-digest");
+    expect(items[items.length - 1]!.action).toBe("message");
+    expect(items[items.length - 1]!.content).toBe("/compact");
+  });
+
+  test("when feedback-digest is gated, queue is briefing → /compact (length 2)", async () => {
+    // Harness condition: pre-seed queue.jsonl with a pending feedback-digest
+    // entry for "ludics" so queueHasPendingFeedbackDigest() returns true and
+    // tryQueueFeedbackDigest short-circuits with { queued: false }. Without
+    // this seed, digest would fire and the length-2 assertion would fail.
+    const qf = join(getTmpDir(), "mag", "queue.jsonl");
+    writeFileSync(
+      qf,
+      JSON.stringify({ id: "seed", action: "feedback-digest", repo: "ludics" }) + "\n",
+    );
+
+    const { magBriefing } = await import("./mag.ts");
+    magBriefing(false);
+
+    const items = readQueue();
+    // Drop the pre-seeded sentinel; only assert on what magBriefing wrote.
+    const written = items.slice(1);
+    expect(written).toHaveLength(2);
+    expect(written[0]!.action).toBe("briefing");
+    expect(written[1]!.action).toBe("message");
+    expect(written[1]!.content).toBe("/compact");
+    // /compact must be last regardless of digest gating.
+    expect(items[items.length - 1]!.action).toBe("message");
+    expect(items[items.length - 1]!.content).toBe("/compact");
   });
 });
 

src/mag.ts

@@ -3314,17 +3314,20 @@ export function magBriefing(wait: boolean = true, timeout: number = 300): void {
   const requestId = queueRequest({ action: "briefing" });
   console.log(`Queued briefing request: ${requestId}`);
 
-  // Auto-compact after briefing — checkpoint compaction (task-a00fc0d9 /
-  // docs/proposals/auto-compact-after-checkpoints.md). Enqueued directly
-  // behind the briefing so it lands before any later automated enqueues.
-  queueRequest({ action: "message", content: "/compact" });
-
   // Auto-queue feedback-digest once daily alongside the briefing trigger.
+  // Lands before /compact so digest can consume the briefing's in-flight
+  // context (task-304a02a6 / docs/proposals/task-304a02a6-reorder-briefing-auto-queue.md).
   const fdResult = tryQueueFeedbackDigest("ludics");
   if (fdResult.queued) {
     console.error("ludics: briefing queued feedback-digest for ludics");
   }
 
+  // Auto-compact after briefing — checkpoint compaction (task-a00fc0d9 /
+  // docs/proposals/auto-compact-after-checkpoints.md). Enqueued unconditionally
+  // as the LAST follow-up so the next session starts fresh, after
+  // feedback-digest has had a chance to consume the briefing context.
+  queueRequest({ action: "message", content: "/compact" });
+
   if (!wait) {
     console.log("Mag will process when ready");
     return;