diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68c6fbc6e3..2088779ed5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,8 @@
 
 ### 🐛 Bug Fixes
 
+- **fix(startup):** best-effort self-heal for a corrupted Turbopack dev cache on Windows ([#6289](https://github.com/diegosouzapw/OmniRoute/issues/6289)). On Windows, `pnpm dev` can fail at startup when Turbopack `mmap`s a persistent-cache SST file and the OS refuses the mapping (`os error 1455` — "paging file too small"), which Turbopack surfaces as a misleading `Module not found: Can't resolve '@/shared/utils/machine'`. This is a **known upstream Turbopack cache-corruption bug — not our code**. The dev launcher (`scripts/dev/run-next.mjs`) now wraps `nextApp.prepare()` and, when it rejects with that signature (`isTurbopackCacheCorruption` in the new `scripts/dev/turbopackCacheHeal.mjs`), purges `.build/next/**/cache/turbopack` and retries **once** with a clear log. **Caveat — best-effort only:** the corruption often surfaces as a runtime overlay rather than a `prepare()` rejection, so this cannot always intercept it; the reliable remedy remains manually deleting the Turbopack cache dir. Regression guard: `tests/unit/turbopack-cache-heal-6289.test.ts`. (thanks @chirag127)
+
 - **fix(providers):** qodercli PAT auth no longer fails with `spawn qodercli ENOENT` on Windows ([#6263](https://github.com/diegosouzapw/OmniRoute/issues/6263)) — `spawnQoderCli` spawned the bare `qodercli` name with `shell:false` and an unenriched env, so the npm `.cmd` wrapper under `%APPDATA%\npm` (a user-PATH directory) was never resolved. It now resolves the absolute `.cmd`/`.exe` path through the existing `getCliRuntimeStatus("qoder")` resolver in `src/shared/services/cliRuntime.ts` (memoized), spawns with `shell` when the target is a `.cmd`/`.bat`, and uses the cliRuntime-enriched env (PATH + PATHEXT + APPDATA); the ENOENT error now lists the searched paths plus the `CLI_QODER_BIN` override. End-to-end spawn on a real Windows host is host-only (Hard Rule #18); the path-resolution logic is unit-tested. Regression guard: `tests/unit/qodercli-windows-resolve-6263.test.ts`. (thanks @chirag127)
 
 - **fix(sse):** the reasoning-token buffer no longer inflates **probe-sized `max_tokens`** ([#6274](https://github.com/diegosouzapw/OmniRoute/issues/6274)) — Claude Code's `/model` capability check sends `max_tokens: 1`, but for a thinking-capable model with a large output cap (e.g. `glm-5.2`) the #3587 headroom heuristic (`max(current + 1000, ceil(current * 1.5))`) rewrote it to `1001` and forwarded that upstream, wasting tokens on a request that was never a genuine reasoning budget. `resolveReasoningBufferedMaxTokens()` (`open-sse/services/reasoningTokenBuffer.ts`) now short-circuits and returns the caller's value verbatim when it is below the new `REASONING_BUFFER_MIN_TRIGGER` (256) threshold — a tiny explicit limit is a probe, not a reasoning request. Real budgets still receive the #3587 headroom unchanged, and the guard runs after the existing capability checks so unknown / non-reasoning models keep returning `null`. Regression guard: `tests/unit/reasoning-token-buffer-6274.test.ts`. (thanks @brightfiscalband)
diff --git a/scripts/dev/run-next.mjs b/scripts/dev/run-next.mjs
index 38f914d2e3..4a402650a8 100644
--- a/scripts/dev/run-next.mjs
+++ b/scripts/dev/run-next.mjs
@@ -11,6 +11,10 @@ import { createResponsesWsProxy } from "./responses-ws-proxy.mjs";
 import { ensurePeerStampToken, stampPeerIp } from "./peer-stamp.mjs";
 import methodGuard from "./http-method-guard.cjs";
 import { ensureNativeSqlite } from "./ensure-native-sqlite.mjs";
+import {
+  isTurbopackCacheCorruption,
+  purgeAllTurbopackCaches,
+} from "./turbopackCacheHeal.mjs";
 import { randomUUID } from "node:crypto";
 
 const { maybeHandleDisallowedMethod } = methodGuard;
@@ -88,17 +92,46 @@ ensurePeerStampToken();
 if (!useTurbopack) {
   delete process.env.TURBOPACK;
 }
-const nextApp = next({
-  dev,
-  dir: process.cwd(),
-  hostname,
-  port: dashboardPort,
-  turbopack: useTurbopack,
-  webpack: !useTurbopack,
-});
+function createNextApp() {
+  return next({
+    dev,
+    dir: process.cwd(),
+    hostname,
+    port: dashboardPort,
+    turbopack: useTurbopack,
+    webpack: !useTurbopack,
+  });
+}
+
+let nextApp = createNextApp();
+
+// Best-effort self-heal for a corrupted Turbopack persistent dev cache (#6289):
+// on Windows an mmap of an SST cache file can fail ("os error 1455" / paging
+// file too small), which Turbopack surfaces as a misleading module-resolve
+// error. This is an UPSTREAM Turbopack cache-corruption bug — not our code.
+// When `prepare()` rejects with that signature we purge the cache and retry
+// ONCE. Caveat: the failure often surfaces as a runtime overlay rather than a
+// `prepare()` rejection, so this cannot always intercept it — the reliable
+// remedy remains manually deleting `.build/next/**/cache/turbopack`.
+async function prepareWithHeal() {
+  try {
+    await nextApp.prepare();
+  } catch (error) {
+    const detail = error instanceof Error ? `${error.message}\n${error.stack ?? ""}` : String(error);
+    if (!useTurbopack || !isTurbopackCacheCorruption(detail)) throw error;
+    console.warn(
+      "[Next] Turbopack dev cache looks corrupted (Windows mmap / os error 1455 — known upstream bug). Purging and retrying once…"
+    );
+    const removed = purgeAllTurbopackCaches();
+    for (const dir of removed) console.warn(`[Next] purged Turbopack cache: ${dir}`);
+    nextApp = createNextApp();
+    await nextApp.prepare();
+    console.warn("[Next] Turbopack dev cache purged; startup retry succeeded.");
+  }
+}
 
 async function start() {
-  await nextApp.prepare();
+  await prepareWithHeal();
 
   const requestHandler = nextApp.getRequestHandler();
   const upgradeHandler = nextApp.getUpgradeHandler();
diff --git a/scripts/dev/turbopackCacheHeal.mjs b/scripts/dev/turbopackCacheHeal.mjs
new file mode 100644
index 0000000000..7b6c2a110f
--- /dev/null
+++ b/scripts/dev/turbopackCacheHeal.mjs
@@ -0,0 +1,74 @@
+// Best-effort self-heal for a corrupted Turbopack persistent dev cache.
+//
+// Context (#6289): on Windows, `pnpm dev` can fail at startup when Turbopack
+// mmaps a persistent-cache SST file and the OS refuses the mapping
+// ("os error 1455" — "paging file too small"). Turbopack then surfaces a
+// misleading `Module not found: Can't resolve '@/shared/utils/machine'`.
+// This is a known UPSTREAM Turbopack cache-corruption bug — NOT our code.
+// The reliable remedy is deleting the Turbopack cache dir; this module lets
+// the dev launcher attempt that automatically once before giving up.
+//
+// Pure + side-effect-isolated so it can be unit-tested without booting Next.
+
+import fs from "node:fs";
+import path from "node:path";
+
+// Signature of the corrupted-cache failure. Kept intentionally broad because
+// the same corruption surfaces through several messages (the raw mmap/SST
+// error, the Windows paging-file error code, and the misleading module-resolve
+// error emitted by Turbopack's "restore task data" step).
+const CORRUPTION_SIGNATURE = /restore task data|mmap .*SST|os error 1455|paging file/i;
+
+/**
+ * True when an error message looks like a corrupted Turbopack persistent cache.
+ * @param {unknown} message
+ * @returns {boolean}
+ */
+export function isTurbopackCacheCorruption(message) {
+  if (message == null) return false;
+  return CORRUPTION_SIGNATURE.test(String(message));
+}
+
+/**
+ * Candidate Turbopack cache directories for a given Next dist dir. Next has
+ * placed the persistent cache under both `<distDir>/cache/turbopack` and
+ * `<distDir>/dev/cache/turbopack` across versions, so purge both.
+ * @param {string} [distDir]
+ * @param {string} [cwd]
+ * @returns {string[]}
+ */
+export function turbopackCacheDirs(
+  distDir = process.env.NEXT_DIST_DIR || ".build/next",
+  cwd = process.cwd()
+) {
+  const base = path.isAbsolute(distDir) ? distDir : path.join(cwd, distDir);
+  return [
+    path.join(base, "cache", "turbopack"),
+    path.join(base, "dev", "cache", "turbopack"),
+  ];
+}
+
+/**
+ * Recursively remove a single Turbopack cache directory.
+ * @param {string} dir
+ * @returns {boolean} true if the directory existed and was removed
+ */
+export function purgeTurbopackCache(dir) {
+  if (!dir || !fs.existsSync(dir)) return false;
+  fs.rmSync(dir, { recursive: true, force: true });
+  return true;
+}
+
+/**
+ * Purge every candidate Turbopack cache directory for the given dist dir.
+ * @param {string} [distDir]
+ * @param {string} [cwd]
+ * @returns {string[]} the directories that existed and were removed
+ */
+export function purgeAllTurbopackCaches(distDir, cwd) {
+  const removed = [];
+  for (const dir of turbopackCacheDirs(distDir, cwd)) {
+    if (purgeTurbopackCache(dir)) removed.push(dir);
+  }
+  return removed;
+}
diff --git a/tests/unit/turbopack-cache-heal-6289.test.ts b/tests/unit/turbopack-cache-heal-6289.test.ts
new file mode 100644
index 0000000000..0a30882fbe
--- /dev/null
+++ b/tests/unit/turbopack-cache-heal-6289.test.ts
@@ -0,0 +1,76 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+import {
+  isTurbopackCacheCorruption,
+  purgeTurbopackCache,
+  turbopackCacheDirs,
+} from "../../scripts/dev/turbopackCacheHeal.mjs";
+
+// Regression for #6289: on Windows, `pnpm dev` fails when Turbopack mmaps a
+// corrupted persistent-cache SST file ("os error 1455" / paging file too
+// small), surfaced as a misleading `Module not found: Can't resolve
+// '@/shared/utils/machine'`. The launcher (scripts/dev/run-next.mjs) uses these
+// pure helpers to detect that signature and purge the Turbopack dev cache
+// before retrying once. This test covers ONLY the pure logic — reproducing the
+// real mmap failure is host-only and out of scope.
+
+test("isTurbopackCacheCorruption matches the corrupted-cache signatures", () => {
+  const matching = [
+    "failed to mmap SST file .build/next/cache/turbopack/data.sst",
+    "Backend error: Storage restore task data failed",
+    "memory map failed: os error 1455",
+    "The paging file is too small for this operation to complete. (os error 1455)",
+    "Module not found: os error 1455 while trying to restore task data",
+  ];
+  for (const msg of matching) {
+    assert.equal(isTurbopackCacheCorruption(msg), true, `should match: ${msg}`);
+  }
+});
+
+test("isTurbopackCacheCorruption returns false for unrelated errors", () => {
+  const unrelated = [
+    "Module not found: Can't resolve '@/shared/utils/machine'",
+    "EADDRINUSE: address already in use :::20128",
+    "TypeError: Cannot read properties of undefined",
+    "",
+    null,
+    undefined,
+  ];
+  for (const msg of unrelated) {
+    assert.equal(isTurbopackCacheCorruption(msg), false, `should NOT match: ${String(msg)}`);
+  }
+});
+
+test("turbopackCacheDirs resolves both known cache layouts under the dist dir", () => {
+  const cwd = "/tmp/omniroute-test";
+  const dirs = turbopackCacheDirs(".build/next", cwd);
+  assert.deepEqual(dirs, [
+    path.join(cwd, ".build/next", "cache", "turbopack"),
+    path.join(cwd, ".build/next", "dev", "cache", "turbopack"),
+  ]);
+});
+
+test("purgeTurbopackCache removes an existing cache/turbopack dir", () => {
+  const tmp = fs.mkdtempSync(path.join(os.tmpdir(), "tp-cache-heal-"));
+  const cacheDir = path.join(tmp, "cache", "turbopack");
+  fs.mkdirSync(cacheDir, { recursive: true });
+  fs.writeFileSync(path.join(cacheDir, "data.sst"), "corrupt");
+  assert.equal(fs.existsSync(cacheDir), true);
+
+  const removed = purgeTurbopackCache(cacheDir);
+
+  assert.equal(removed, true);
+  assert.equal(fs.existsSync(cacheDir), false);
+
+  fs.rmSync(tmp, { recursive: true, force: true });
+});
+
+test("purgeTurbopackCache is a no-op (returns false) when the dir is absent", () => {
+  const missing = path.join(os.tmpdir(), "tp-cache-heal-missing-does-not-exist");
+  assert.equal(fs.existsSync(missing), false);
+  assert.equal(purgeTurbopackCache(missing), false);
+});