fix(ci): type-check drift — bun-only fs/promises.exists + floating resolution

The workflow failed on 'Module "fs/promises" has no exported member
"exists"' while every local run passed. Root cause chain:

1. bun install --force re-resolved dependencies in CI. Nothing pins
   @types/node (no lockfile — gitignored by policy; every path to it is
   a floating "*": @types/pidusage and bun-types both declare "*"),
   so CI silently typechecked against whatever @types/node was
   registry-latest that day. Reproduced locally: 22.20.2 fails the old
   import, 26.4.1 passes — that's the local-vs-CI split.
2. With stock @types/node winning the fs/promises module declaration,
   the Bun-only exists extension stopped typechecking.

Fixes, layered:
- tests/log-manager.test.ts: existsSync from node:fs — typed by both
  @types/node and bun-types, identical behavior (the only fs/promises
  Bun-extension import in the repo; everything else is stock Node API)
- @types/node pinned as a direct devDependency (22.20.2 — exactly what
  CI was resolving): a direct dep overrides the floating "*" transitives
- workflow: bun install --frozen-lockfile — the correct CI posture;
  installs exactly what exists when a lockfile is present, instead of
  re-resolving daily
- devDeps pinned: @types/bun ^1.4.2, bun-types ^1.4.2 (no more floating
  "latest" tag)

Verified: tsc clean under BOTH @types/node 26.4.1 and 22.20.2; the
workflow's exact bun 1.3.9 + frozen install + tsc in a pristine copy;
log-manager 10/10; full suite 597/597.

Author: ra-sun-god

.github/workflows/test.yml

@@ -31,8 +31,13 @@ jobs:
         run: bun --version
 
       # Install dependencies
+      # --frozen-lockfile: install EXACTLY the committed bun.lock. The old
+      # `--force` re-resolved from the registry on every run, letting
+      # floating transitives (e.g. @types/node via @types/pidusage's "*")
+      # drift to whatever was "latest" that day — the moving target behind
+      # the "fs/promises has no exported member 'exists'" CI failure.
       - name: Install dependencies
-        run: bun install --force
+        run: bun install --frozen-lockfile
 
       # Type check (TS)
       - name: Type check

package.json

@@ -74,9 +74,10 @@
                 "pidusage": "^4.0.1"
         },
         "devDependencies": {
-                "@types/bun": "^1.3.14",
+                "@types/bun": "^1.4.2",
+                "@types/node": "22.20.2",
                 "@types/pidusage": "^2.0.5",
-                "bun-types": "latest",
+                "bun-types": "^1.4.2",
                 "typescript": "^5.9.3"
         }
 }

tests/log-manager.test.ts

@@ -1,5 +1,10 @@
 import { describe, test, expect, beforeEach, afterEach } from "bun:test";
-import { mkdir, rm, writeFile, readFile, exists, readdir } from "fs/promises";
+import { mkdir, rm, writeFile, readFile, readdir } from "fs/promises";
+// NB: no `exists` here — fs/promises.exists is a BUN-ONLY extension. When
+// tsc resolves fs/promises against stock @types/node (CI's install can
+// re-resolve it transitively), the import stops typechecking. existsSync
+// is typed by both @types/node and bun-types and behaves identically here.
+import { existsSync } from "node:fs";
 import { join } from "path";
 import { tmpdir } from "os";
 
@@ -19,15 +24,15 @@ describe("Log File Management", () => {
     const logFile = join(LOG_DIR, "app-out.log");
     await writeFile(logFile, "");
 
-    const fileExists = await exists(logFile);
+    const fileExists = existsSync(logFile);
     expect(fileExists).toBe(true);
   });
 
   test("should create stderr log file", async () => {
     const logFile = join(LOG_DIR, "app-error.log");
     await writeFile(logFile, "");
 
-    const fileExists = await exists(logFile);
+    const fileExists = existsSync(logFile);
     expect(fileExists).toBe(true);
   });