refactor(infra): share shell env timeout normalization

src/infra/shell-env.test.ts

@@ -1,6 +1,8 @@
 import { describe, expect, it, vi } from "vitest";
 import {
+  getShellPathFromLoginShell,
   loadShellEnvFallback,
+  resetShellPathCacheForTests,
   resolveShellEnvFallbackTimeoutMs,
   shouldEnableShellEnvFallback,
 } from "./shell-env.js";
@@ -71,4 +73,42 @@ describe("shell env fallback", () => {
     expect(env.DISCORD_BOT_TOKEN).toBe("discord");
     expect(exec2).not.toHaveBeenCalled();
   });
+
+  it("resolves PATH via login shell and caches it", () => {
+    resetShellPathCacheForTests();
+    const exec = vi.fn(() => Buffer.from("PATH=/usr/local/bin:/usr/bin\0HOME=/tmp\0"));
+
+    const first = getShellPathFromLoginShell({
+      env: {} as NodeJS.ProcessEnv,
+      exec: exec as unknown as Parameters<typeof getShellPathFromLoginShell>[0]["exec"],
+    });
+    const second = getShellPathFromLoginShell({
+      env: {} as NodeJS.ProcessEnv,
+      exec: exec as unknown as Parameters<typeof getShellPathFromLoginShell>[0]["exec"],
+    });
+
+    expect(first).toBe("/usr/local/bin:/usr/bin");
+    expect(second).toBe("/usr/local/bin:/usr/bin");
+    expect(exec).toHaveBeenCalledOnce();
+  });
+
+  it("returns null on shell env read failure and caches null", () => {
+    resetShellPathCacheForTests();
+    const exec = vi.fn(() => {
+      throw new Error("exec failed");
+    });
+
+    const first = getShellPathFromLoginShell({
+      env: {} as NodeJS.ProcessEnv,
+      exec: exec as unknown as Parameters<typeof getShellPathFromLoginShell>[0]["exec"],
+    });
+    const second = getShellPathFromLoginShell({
+      env: {} as NodeJS.ProcessEnv,
+      exec: exec as unknown as Parameters<typeof getShellPathFromLoginShell>[0]["exec"],
+    });
+
+    expect(first).toBeNull();
+    expect(second).toBeNull();
+    expect(exec).toHaveBeenCalledOnce();
+  });
 });

src/infra/shell-env.ts

@@ -6,6 +6,13 @@ const DEFAULT_MAX_BUFFER_BYTES = 2 * 1024 * 1024;
 let lastAppliedKeys: string[] = [];
 let cachedShellPath: string | null | undefined;
 
+function resolveTimeoutMs(timeoutMs: number | undefined): number {
+  if (typeof timeoutMs !== "number" || !Number.isFinite(timeoutMs)) {
+    return DEFAULT_TIMEOUT_MS;
+  }
+  return Math.max(0, timeoutMs);
+}
+
 function resolveShell(env: NodeJS.ProcessEnv): string {
   const shell = env.SHELL?.trim();
   return shell && shell.length > 0 ? shell : "/bin/sh";
@@ -76,10 +83,7 @@ export function loadShellEnvFallback(opts: ShellEnvFallbackOptions): ShellEnvFal
     return { ok: true, applied: [], skippedReason: "already-has-keys" };
   }
 
-  const timeoutMs =
-    typeof opts.timeoutMs === "number" && Number.isFinite(opts.timeoutMs)
-      ? Math.max(0, opts.timeoutMs)
-      : DEFAULT_TIMEOUT_MS;
+  const timeoutMs = resolveTimeoutMs(opts.timeoutMs);
 
   const shell = resolveShell(opts.env);
 
@@ -146,10 +150,7 @@ export function getShellPathFromLoginShell(opts: {
   }
 
   const exec = opts.exec ?? execFileSync;
-  const timeoutMs =
-    typeof opts.timeoutMs === "number" && Number.isFinite(opts.timeoutMs)
-      ? Math.max(0, opts.timeoutMs)
-      : DEFAULT_TIMEOUT_MS;
+  const timeoutMs = resolveTimeoutMs(opts.timeoutMs);
   const shell = resolveShell(opts.env);
 
   let stdout: Buffer;