fix(agent): stabilize large tool results

tests/runtime/opencodeToolOutputCleanup.test.ts

@@ -0,0 +1,62 @@
+import { describe, expect, test } from "bun:test";
+import {
+  lstat,
+  mkdir,
+  mkdtemp,
+  readFile,
+  rm,
+  stat,
+  symlink,
+  utimes,
+  writeFile,
+} from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+import { cleanupExpiredToolOutputs } from "../../src/runtime/opencodeToolOutputCleanup.js";
+
+describe("cleanupExpiredToolOutputs", () => {
+  test("removes only expired regular tool output files", async () => {
+    const directory = await mkdtemp(join(tmpdir(), "opencode-tool-output-cleanup-"));
+    const expired = join(directory, "tool_expired");
+    const current = join(directory, "tool_current");
+    const unrelated = join(directory, "keep.txt");
+    const toolDirectory = join(directory, "tool_directory");
+    const toolSymlink = join(directory, "tool_symlink");
+    try {
+      await Promise.all([
+        writeFile(expired, "expired"),
+        writeFile(current, "current"),
+        writeFile(unrelated, "unrelated"),
+        mkdir(toolDirectory),
+      ]);
+      await symlink(unrelated, toolSymlink);
+      const now = Date.now();
+      const old = new Date(now - 8 * 24 * 60 * 60 * 1000);
+      await utimes(expired, old, old);
+
+      const result = await cleanupExpiredToolOutputs(
+        directory,
+        7 * 24 * 60 * 60 * 1000,
+        now,
+      );
+
+      expect(result).toEqual({ removed: 1, scanned: 5 });
+      await expect(stat(expired)).rejects.toMatchObject({ code: "ENOENT" });
+      expect(await readFile(current, "utf8")).toBe("current");
+      expect(await readFile(unrelated, "utf8")).toBe("unrelated");
+      expect((await stat(toolDirectory)).isDirectory()).toBe(true);
+      expect((await lstat(toolSymlink)).isSymbolicLink()).toBe(true);
+    } finally {
+      await rm(directory, { force: true, recursive: true });
+    }
+  });
+
+  test("treats a missing tool output directory as empty", async () => {
+    const directory = join(tmpdir(), `missing-tool-output-${crypto.randomUUID()}`);
+    await expect(cleanupExpiredToolOutputs(directory, 1_000)).resolves.toEqual({
+      removed: 0,
+      scanned: 0,
+    });
+  });
+});