diff --git a/open-sse/services/compression/compressionWorkerPool.ts b/open-sse/services/compression/compressionWorkerPool.ts
index 109940a14d..352aabd39c 100644
--- a/open-sse/services/compression/compressionWorkerPool.ts
+++ b/open-sse/services/compression/compressionWorkerPool.ts
@@ -1,6 +1,5 @@
 import { existsSync } from "node:fs";
-import { dirname, join } from "node:path";
-import { fileURLToPath, pathToFileURL } from "node:url";
+import { dirname, join, resolve } from "node:path";
 import { Worker } from "node:worker_threads";
 import type { CompressionResult } from "./types.ts";
 import type { StackedCompressionStep } from "./strategySelector.ts";
@@ -14,14 +13,70 @@ function positiveInteger(value: string | undefined, fallback: number): number {
   const parsed = Number(value);
   return Number.isSafeInteger(parsed) && parsed > 0 ? parsed : fallback;
 }
-function workerUrl(): URL {
-  const dir = dirname(fileURLToPath(import.meta.url));
-  for (const name of ["compressionWorker.js", "compressionWorker.ts"]) {
-    const candidate = join(dir, name);
-    if (existsSync(candidate)) return pathToFileURL(candidate);
+
+/** Relative path (from an install root) to the compression worker. */
+const WORKER_JS_REL = join("open-sse", "services", "compression", "compressionWorker.js");
+const WORKER_TS_REL = join("open-sse", "services", "compression", "compressionWorker.ts");
+
+const MAX_WALK_UP = 8;
+
+/**
+ * Walk up from each anchor directory (≤ MAX_WALK_UP levels) and return the first
+ * ancestor that actually contains `relPath`, or null. Pure + exported for tests.
+ *
+ * This deliberately avoids `import.meta.url`/`__dirname` (both dead in the standalone
+ * bundle) — see the LLMLingua worker comments in llmlingua/worker.ts.
+ */
+export function firstAncestorWith(anchors: string[], relPath: string): string | null {
+  for (const anchor of anchors) {
+    if (!anchor) continue;
+    let dir = resolve(anchor);
+    for (let i = 0; i <= MAX_WALK_UP; i++) {
+      if (existsSync(join(dir, relPath))) return dir;
+      const parent = dirname(dir);
+      if (parent === dir) break;
+      dir = parent;
+    }
   }
-  return pathToFileURL(join(dir, "compressionWorker.js"));
+  return null;
 }
+
+/**
+ * Runtime install-root anchors that SURVIVE the standalone bundle:
+ *  - `process.cwd()` — `dist/server.js` runs `process.chdir(__dirname)` → the dist root.
+ *  - `dirname(process.argv[1])` — the entry script (server.js / bin), walked up.
+ */
+function runtimeAnchors(): string[] {
+  const anchors = [process.cwd()];
+  const argv1 = process.argv[1];
+  if (typeof argv1 === "string" && argv1) anchors.push(dirname(argv1));
+  return anchors;
+}
+
+/**
+ * Resolve the worker entry file across dev and prod WITHOUT `import.meta.url`.
+ *
+ * Prod: the worker is likely a .js file under the install root
+ * Dev: the same relative path resolves to the `.ts` source under the project
+ * root (cwd) and runs via the default Node.js loader.
+ *
+ * First existing candidate wins. Exported for tests.
+ */
+export function resolveWorkerFile(): string {
+  const anchors = runtimeAnchors();
+
+  // Prod first: the .js under the install root.
+  const jsRoot = firstAncestorWith(anchors, WORKER_JS_REL);
+  if (jsRoot) return join(jsRoot, WORKER_JS_REL);
+
+  // Dev: the .ts source.
+  const tsRoot = firstAncestorWith(anchors, WORKER_TS_REL);
+  if (tsRoot) return join(tsRoot, WORKER_TS_REL);
+
+  // Nothing found — return a cwd-relative .js path; the spawn will fail-open.
+  return join(process.cwd(), WORKER_JS_REL);
+}
+
 function unchanged(body: Record<string, unknown>): CompressionResult {
   return { body, compressed: false, stats: null };
 }
@@ -80,7 +135,7 @@ export class CompressionWorkerPool {
   }
   private spawn(): PoolWorker {
     const slot: PoolWorker = {
-      worker: new Worker(workerUrl()),
+      worker: new Worker(resolveWorkerFile()),
       job: null,
       timeout: null,
       idle: null,
diff --git a/tests/unit/compression/compression-worker-file-resolution.test.ts b/tests/unit/compression/compression-worker-file-resolution.test.ts
new file mode 100644
index 0000000000..56cbd335ec
--- /dev/null
+++ b/tests/unit/compression/compression-worker-file-resolution.test.ts
@@ -0,0 +1,143 @@
+import assert from "node:assert/strict";
+import { after, describe, it } from "node:test";
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync, realpathSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import {
+  firstAncestorWith,
+  resolveWorkerFile,
+} from "../../../open-sse/services/compression/compressionWorkerPool.ts";
+
+/**
+ * Regression tests for the runtime-anchor worker-file resolution (#12183): the
+ * standalone bundle kills `import.meta.url`/`__dirname`, so the pool resolves
+ * `compressionWorker.{js,ts}` from `process.cwd()` and `dirname(process.argv[1])`
+ * with a bounded walk-up — the same pattern documented in
+ * open-sse/services/compression/engines/llmlingua/worker.ts.
+ *
+ * All fixtures live in mkdtemp sandboxes; the real repo tree is never touched —
+ * the sandboxes sit under os.tmpdir(), whose ancestors do not contain an
+ * `open-sse/services/compression/` install root, so the walk-up cannot escape
+ * into the actual project.
+ */
+
+const WORKER_JS_REL = join("open-sse", "services", "compression", "compressionWorker.js");
+const WORKER_TS_REL = join("open-sse", "services", "compression", "compressionWorker.ts");
+
+const sandboxes: string[] = [];
+
+function makeSandbox(): string {
+  // realpath so assertions survive tmpdir symlinks (e.g. /tmp → /private/tmp).
+  const dir = realpathSync(mkdtempSync(join(tmpdir(), "omni-worker-anchors-")));
+  sandboxes.push(dir);
+  return dir;
+}
+
+/** Creates `<root>/open-sse/services/compression/<fileName>` with stub content. */
+function makeInstallRoot(root: string, fileName: string): void {
+  const dir = join(root, "open-sse", "services", "compression");
+  mkdirSync(dir, { recursive: true });
+  writeFileSync(join(dir, fileName), "// test stub worker\n");
+}
+
+/** Runs `fn` with a fake cwd + argv[1], restoring both afterwards. */
+function withRuntime<T>(cwd: string, argv1: string, fn: () => T): T {
+  const originalCwd = process.cwd();
+  const originalArgv1 = process.argv[1];
+  process.chdir(cwd);
+  process.argv[1] = argv1;
+  try {
+    return fn();
+  } finally {
+    process.argv[1] = originalArgv1;
+    process.chdir(originalCwd);
+  }
+}
+
+after(() => {
+  for (const dir of sandboxes) rmSync(dir, { recursive: true, force: true });
+});
+
+describe("resolveWorkerFile (runtime anchors)", () => {
+  it("resolves the .js worker from the cwd anchor", () => {
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.js");
+    const elsewhere = makeSandbox();
+    const resolved = withRuntime(installRoot, join(elsewhere, "server.js"), () =>
+      resolveWorkerFile()
+    );
+    assert.equal(resolved, join(installRoot, WORKER_JS_REL));
+  });
+
+  it("resolves the .js worker from dirname(argv[1]) when cwd has none", () => {
+    const emptyCwd = makeSandbox();
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.js");
+    const resolved = withRuntime(emptyCwd, join(installRoot, "server.js"), () =>
+      resolveWorkerFile()
+    );
+    assert.equal(resolved, join(installRoot, WORKER_JS_REL));
+  });
+
+  it("walks up from a nested cwd until it finds the install root", () => {
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.js");
+    const nested = join(installRoot, "a", "b", "c");
+    mkdirSync(nested, { recursive: true });
+    const elsewhere = makeSandbox();
+    const resolved = withRuntime(nested, join(elsewhere, "server.js"), () => resolveWorkerFile());
+    assert.equal(resolved, join(installRoot, WORKER_JS_REL));
+  });
+
+  it("falls back to the .ts source when no .js exists (dev loader path)", () => {
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.ts");
+    const elsewhere = makeSandbox();
+    const resolved = withRuntime(installRoot, join(elsewhere, "server.js"), () =>
+      resolveWorkerFile()
+    );
+    assert.equal(resolved, join(installRoot, WORKER_TS_REL));
+  });
+
+  it("prefers a .js root on ANY anchor over a .ts root (prod-first ordering)", () => {
+    const tsRoot = makeSandbox();
+    makeInstallRoot(tsRoot, "compressionWorker.ts");
+    const jsRoot = makeSandbox();
+    makeInstallRoot(jsRoot, "compressionWorker.js");
+    // cwd only has the .ts source; argv[1] sits in the .js install root.
+    const resolved = withRuntime(tsRoot, join(jsRoot, "server.js"), () => resolveWorkerFile());
+    assert.equal(resolved, join(jsRoot, WORKER_JS_REL));
+  });
+
+  it("returns the cwd-relative .js fallback (without throwing) when nothing exists", () => {
+    const emptyCwd = makeSandbox();
+    const emptyBin = makeSandbox();
+    const resolved = withRuntime(emptyCwd, join(emptyBin, "server.js"), () => resolveWorkerFile());
+    assert.equal(resolved, join(emptyCwd, WORKER_JS_REL));
+  });
+});
+
+describe("firstAncestorWith", () => {
+  it("returns the anchor itself when it already contains relPath", () => {
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.js");
+    assert.equal(firstAncestorWith([installRoot], WORKER_JS_REL), installRoot);
+  });
+
+  it("skips empty anchors and returns null when nothing matches", () => {
+    const empty = makeSandbox();
+    assert.equal(firstAncestorWith(["", empty], WORKER_JS_REL), null);
+    assert.equal(firstAncestorWith([], WORKER_JS_REL), null);
+  });
+
+  it("finds a root up to 8 levels above the anchor, but not 9 (walk-up cap)", () => {
+    const installRoot = makeSandbox();
+    makeInstallRoot(installRoot, "compressionWorker.js");
+    const eightDeep = join(installRoot, ...Array.from({ length: 8 }, (_, i) => `d${i}`));
+    mkdirSync(eightDeep, { recursive: true });
+    assert.equal(firstAncestorWith([eightDeep], WORKER_JS_REL), installRoot);
+    const nineDeep = join(installRoot, ...Array.from({ length: 9 }, (_, i) => `d${i}`));
+    mkdirSync(nineDeep, { recursive: true });
+    assert.equal(firstAncestorWith([nineDeep], WORKER_JS_REL), null);
+  });
+});