diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index 276245d30..904d2f0b9 100644
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -184,8 +184,10 @@ jobs:
         # spawns and Windows is ~5x slower than macOS at those, so the unsharded
         # run crept past the 15-min watchdog in run-cross-platform.ts. vitest
         # shards by file COUNT, not runtime, so the heaviest spawn suites can
-        # cluster on one shard; 3 shards keep even the busiest Windows shard
-        # comfortably under the watchdog (macOS had margin either way).
+        # cluster on one shard. The busiest Windows shard has grown to the old
+        # 15-minute watchdog (14m57s on the v1.6.10-rc.19 green run, one
+        # observed timeout since — #2449), so the job env below raises the
+        # per-shard watchdog to 20 minutes, still bounded by timeout-minutes.
         # Shard indices come from the shard-plan job (single source of truth):
         # its TOTAL drives this list and the /N in the job name + --shard arg.
         shard: ${{ fromJSON(needs.shard-plan.outputs.shards) }}
@@ -204,6 +206,10 @@ jobs:
     env:
       GITNEXUS_REQUIRE_FTS: '1'
       GITNEXUS_E2E_CLI: dist
+      # #2449: hosted Windows runners intermittently push the busiest shard past
+      # the default 15-minute watchdog. 20 minutes restores real headroom while
+      # the 25-minute job timeout above still bounds a genuine hang.
+      GITNEXUS_CROSS_PLATFORM_TIMEOUT_MINUTES: '20'
     steps:
       # persist-credentials: false — runs tests only, never pushes (zizmor
       # credential-persistence / artipacked audit).
diff --git a/gitnexus/scripts/run-cross-platform.ts b/gitnexus/scripts/run-cross-platform.ts
index c1eed5c9a..3b829e3ca 100644
--- a/gitnexus/scripts/run-cross-platform.ts
+++ b/gitnexus/scripts/run-cross-platform.ts
@@ -48,10 +48,11 @@ try {
 
 // Per-shard watchdog, default 15 min. Sharding splits the file list by COUNT, not
 // runtime, so the heaviest spawn suites can cluster on one shard — what this
-// bounds is the *busiest* shard, not an even 1/n of wall-clock. With 3 shards
-// even that shard clears the watchdog, where the whole unsharded Windows run
-// used to trip it. Allow CI/manual runs to add headroom without editing the
-// script again.
+// bounds is the *busiest* shard, not an even 1/n of wall-clock. The busiest
+// Windows shard has grown to the default (14m57s on the v1.6.10-rc.19 green
+// run, one observed timeout since — #2449), so CI raises the budget to 20
+// minutes via GITNEXUS_CROSS_PLATFORM_TIMEOUT_MINUTES; the default stays 15
+// for local runs.
 const DEFAULT_TIMEOUT_MIN = 15;
 const timeoutMinutes = Number.parseInt(
   process.env.GITNEXUS_CROSS_PLATFORM_TIMEOUT_MINUTES ?? String(DEFAULT_TIMEOUT_MIN),
@@ -67,6 +68,7 @@ console.log(
     `${shardArg ? ` (${shardArg.replace('--shard=', 'shard ')})` : ''}...\n`,
 );
 
+const startedAt = Date.now();
 try {
   execFileSync('npx', ['vitest', 'run', ...ALL_CROSS_PLATFORM, ...(shardArg ? [shardArg] : [])], {
     cwd: ROOT,
@@ -76,9 +78,22 @@ try {
   });
 } catch (err) {
   // execFileSync sets `killed`/`signal` when the watchdog above kills vitest.
-  const e = err as { killed?: boolean; signal?: NodeJS.Signals | null };
+  const e = err as {
+    killed?: boolean;
+    signal?: NodeJS.Signals | null;
+    status?: number | null;
+    code?: string;
+  };
   if (e.killed || e.signal) {
     console.error(`vitest timed out after ${Math.round(timeoutMs / 60_000)} minutes`);
   }
+  // #2449: Windows shards have died with a bare `status: null`, empty stderr
+  // and nothing to triage from. Always leave the child's exit facts behind.
+  const elapsedSec = Math.round((Date.now() - startedAt) / 1000);
+  console.error(
+    `vitest exited abnormally: status=${e.status ?? 'null'} signal=${e.signal ?? 'none'} ` +
+      `killed=${e.killed === true} spawnCode=${e.code ?? 'none'} elapsed=${elapsedSec}s ` +
+      `budget=${Math.round(timeoutMs / 60_000)}min`,
+  );
   process.exit(1);
 }