fix: add compaction headroom for memory writes

src/agents/pi-settings.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it, vi } from "vitest";
+
+import {
+  DEFAULT_PI_COMPACTION_RESERVE_TOKENS_FLOOR,
+  ensurePiCompactionReserveTokens,
+} from "./pi-settings.js";
+
+describe("ensurePiCompactionReserveTokens", () => {
+  it("bumps reserveTokens when below floor", () => {
+    const settingsManager = {
+      getCompactionReserveTokens: () => 16_384,
+      applyOverrides: vi.fn(),
+    };
+
+    const result = ensurePiCompactionReserveTokens({ settingsManager });
+
+    expect(result).toEqual({
+      didOverride: true,
+      reserveTokens: DEFAULT_PI_COMPACTION_RESERVE_TOKENS_FLOOR,
+    });
+    expect(settingsManager.applyOverrides).toHaveBeenCalledWith({
+      compaction: { reserveTokens: DEFAULT_PI_COMPACTION_RESERVE_TOKENS_FLOOR },
+    });
+  });
+
+  it("does not override when already above floor", () => {
+    const settingsManager = {
+      getCompactionReserveTokens: () => 32_000,
+      applyOverrides: vi.fn(),
+    };
+
+    const result = ensurePiCompactionReserveTokens({ settingsManager });
+
+    expect(result).toEqual({ didOverride: false, reserveTokens: 32_000 });
+    expect(settingsManager.applyOverrides).not.toHaveBeenCalled();
+  });
+});