diff --git a/src/server/__tests__/agent-hooks.test.ts b/src/server/__tests__/agent-hooks.test.ts
index a5cedacf..009c58df 100644
--- a/src/server/__tests__/agent-hooks.test.ts
+++ b/src/server/__tests__/agent-hooks.test.ts
@@ -1,9 +1,54 @@
 import { describe, expect, it } from "vitest";
+import { spawn, spawnSync } from "node:child_process";
 import * as fs from "node:fs";
+import * as http from "node:http";
+import type { AddressInfo } from "node:net";
 import * as os from "node:os";
 import * as path from "node:path";
 import { installAgentHooks } from "../../../electron/agent-hooks";
 
+// Every PowerShell on PATH: pwsh (preinstalled on the CI runners) and, on
+// Windows, Windows PowerShell 5.1 — the host issue #130 was reported against.
+const POWERSHELLS = (process.platform === "win32" ? ["pwsh", "powershell"] : ["pwsh"]).filter(
+  (bin) =>
+    spawnSync(bin, ["-NoProfile", "-NonInteractive", "-Command", "exit 0"], { stdio: "ignore" })
+      .status === 0,
+);
+
+/** Install the Windows Claude hooks into a temp project and look commands up by event. */
+function windowsClaudeHookCommands(): (event: string, matcher?: string) => string {
+  const cwd = fs.mkdtempSync(path.join(os.tmpdir(), "mc-hooks-"));
+  installAgentHooks("claude-code", cwd, "win32");
+  const settings = JSON.parse(
+    fs.readFileSync(path.join(cwd, ".claude", "settings.local.json"), "utf8"),
+  ) as {
+    hooks: Record<string, Array<{ matcher?: string; hooks?: Array<{ command?: string }> }>>;
+  };
+  return (event, matcher) =>
+    settings.hooks[event]?.find((g) => matcher === undefined || g.matcher === matcher)
+      ?.hooks?.[0]?.command ?? "";
+}
+
+function runHook(
+  bin: string,
+  command: string,
+  stdin: Buffer,
+  env: NodeJS.ProcessEnv,
+): Promise<{ code: number | null; stdout: Buffer; stderr: string }> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(bin, ["-NoProfile", "-NonInteractive", "-Command", command], { env });
+    const out: Buffer[] = [];
+    const err: Buffer[] = [];
+    child.stdout.on("data", (chunk: Buffer) => out.push(chunk));
+    child.stderr.on("data", (chunk: Buffer) => err.push(chunk));
+    child.on("error", reject);
+    child.on("close", (code) =>
+      resolve({ code, stdout: Buffer.concat(out), stderr: Buffer.concat(err).toString("utf8") }),
+    );
+    child.stdin.end(stdin);
+  });
+}
+
 describe("agent hook installation", () => {
   it("does not register Claude interrupt hooks", () => {
     const cwd = fs.mkdtempSync(path.join(os.tmpdir(), "mc-hooks-"));
@@ -223,11 +268,159 @@ describe("agent hook installation", () => {
       type: "command",
       shell: "powershell",
     });
-    expect(hook?.command).toContain("Invoke-RestMethod");
+    expect(hook?.command).toContain("Invoke-WebRequest");
     expect(hook?.command).toContain("$env:MC_API_URL");
     expect(hook?.command).not.toContain("if [");
   });
 
+  it("keeps non-Latin-1 payloads intact through the Windows PowerShell hooks", () => {
+    const commandFor = windowsClaudeHookCommands();
+    const askQuestion = commandFor("PreToolUse", "AskUserQuestion");
+    const userPrompt = commandFor("UserPromptSubmit");
+    expect(askQuestion).not.toBe("");
+    expect(userPrompt).not.toBe("");
+
+    // Windows PowerShell 5.1 decodes stdin with the console code page and sends
+    // a string -Body as ISO-8859-1, so a Cyrillic AskUserQuestion reached the
+    // overlay as "?????" (issue #130). Stdin must be read as UTF-8 bytes and the
+    // body posted as bytes, which both 5.1 and pwsh send verbatim.
+    for (const command of [askQuestion, userPrompt]) {
+      expect(command).toContain(
+        "[System.IO.StreamReader]::new([Console]::OpenStandardInput(), [System.Text.UTF8Encoding]::new($false))",
+      );
+      expect(command).toContain("[System.Text.Encoding]::UTF8.GetBytes($payload)");
+      expect(command).toContain("-Body $body");
+      expect(command).toContain('-ContentType "application/json; charset=utf-8"');
+      expect(command).not.toContain("[Console]::In.ReadToEnd()");
+      expect(command).not.toContain("-Body $payload");
+    }
+
+    // injectContext events hand Claude the server's response bytes untouched
+    // (no ISO-8859-1 decode + ConvertTo-Json round trip); status-only events
+    // discard the response.
+    expect(userPrompt).toContain("$r.RawContentStream.ToArray()");
+    expect(userPrompt).toContain("[Console]::OpenStandardOutput()");
+    expect(userPrompt).not.toContain("ConvertTo-Json");
+    expect(userPrompt).not.toContain("Out-Null");
+    expect(askQuestion).toContain("| Out-Null");
+    expect(askQuestion).not.toContain("OpenStandardOutput");
+  });
+
+  // The substring assertions above can't tell a script that parses from one
+  // that doesn't, so run the generated commands for real against a local server
+  // and compare what crosses the wire in both directions.
+  it.skipIf(POWERSHELLS.length === 0)(
+    "round-trips UTF-8 through the generated PowerShell hooks when executed",
+    async () => {
+      const commandFor = windowsClaudeHookCommands();
+      const payload = Buffer.from(
+        JSON.stringify({
+          hook_event_name: "PreToolUse",
+          tool_input: { questions: [{ question: "Какой вариант выбрать? — 日本語 🚀" }] },
+        }),
+        "utf8",
+      );
+      const injected = Buffer.from(
+        JSON.stringify({
+          hookSpecificOutput: {
+            hookEventName: "UserPromptSubmit",
+            additionalContext: "Память проекта — 記憶 🧠",
+          },
+        }),
+        "utf8",
+      );
+
+      const received: Array<{ url: URL; headers: http.IncomingHttpHeaders; body: string }> = [];
+      const server = http.createServer((req, res) => {
+        const chunks: Buffer[] = [];
+        req.on("data", (chunk: Buffer) => chunks.push(chunk));
+        req.on("end", () => {
+          received.push({
+            url: new URL(req.url ?? "", "http://127.0.0.1"),
+            headers: req.headers,
+            body: Buffer.concat(chunks).toString("utf8"),
+          });
+          res.writeHead(200, { "content-type": "application/json" });
+          res.end(injected);
+        });
+      });
+      await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
+      const env = {
+        ...process.env,
+        MC_TASK_ID: "task 1/a",
+        MC_API_URL: `http://127.0.0.1:${(server.address() as AddressInfo).port}`,
+        MC_API_TOKEN: "test-token",
+      };
+
+      try {
+        for (const bin of POWERSHELLS) {
+          received.length = 0;
+
+          // Status-only event: the payload arrives intact, stdout stays empty.
+          const ask = await runHook(bin, commandFor("PreToolUse", "AskUserQuestion"), payload, env);
+          expect(ask.stderr, bin).toBe("");
+          expect(ask.code, bin).toBe(0);
+          expect(ask.stdout.toString("utf8"), bin).toBe("");
+
+          // injectContext event: the response reaches stdout byte for byte.
+          const prompt = await runHook(bin, commandFor("UserPromptSubmit"), payload, env);
+          expect(prompt.stderr, bin).toBe("");
+          expect(prompt.code, bin).toBe(0);
+          expect(prompt.stdout.toString("utf8"), bin).toBe(injected.toString("utf8"));
+
+          expect(received.map((r) => r.url.searchParams.get("hookEvent")), bin).toEqual([
+            "PreToolUse",
+            "UserPromptSubmit",
+          ]);
+          for (const request of received) {
+            expect(request.url.pathname, bin).toBe("/api/hooks/claude");
+            expect(request.url.searchParams.get("taskId"), bin).toBe("task 1/a");
+            expect(request.headers.authorization, bin).toBe("Bearer test-token");
+            expect(request.headers["content-type"], bin).toBe("application/json; charset=utf-8");
+            expect(request.body, bin).toBe(payload.toString("utf8"));
+          }
+        }
+      } finally {
+        server.closeAllConnections();
+        await new Promise<void>((resolve) => server.close(() => resolve()));
+      }
+    },
+    60_000,
+  );
+
+  // `catch {}` swallows the error but leaves `$?` false, which `-Command` turns
+  // into exit code 1 — and Claude reports any non-zero hook exit as a hook
+  // error. The POSIX hook ends in `|| true`; this one must exit 0 as well.
+  it.skipIf(POWERSHELLS.length === 0)(
+    "exits 0 and stays silent when Mission Control is unreachable",
+    async () => {
+      const commandFor = windowsClaudeHookCommands();
+      const server = http.createServer();
+      await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
+      const { port } = server.address() as AddressInfo;
+      await new Promise<void>((resolve) => server.close(() => resolve()));
+      const env = {
+        ...process.env,
+        MC_TASK_ID: "task-1",
+        MC_API_URL: `http://127.0.0.1:${port}`,
+        MC_API_TOKEN: "test-token",
+      };
+
+      for (const bin of POWERSHELLS) {
+        for (const command of [
+          commandFor("PreToolUse", "AskUserQuestion"),
+          commandFor("UserPromptSubmit"),
+        ]) {
+          const down = await runHook(bin, command, Buffer.from("{}", "utf8"), env);
+          expect(down.stderr, bin).toBe("");
+          expect(down.stdout.toString("utf8"), bin).toBe("");
+          expect(down.code, bin).toBe(0);
+        }
+      }
+    },
+    60_000,
+  );
+
   it("registers Codex lifecycle hooks in Codex's matcher-group format", () => {
     const cwd = fs.mkdtempSync(path.join(os.tmpdir(), "mc-hooks-"));
 
diff --git a/src/server/__tests__/ask-user-question-api.test.ts b/src/server/__tests__/ask-user-question-api.test.ts
index 29718375..5cb9a0ef 100644
--- a/src/server/__tests__/ask-user-question-api.test.ts
+++ b/src/server/__tests__/ask-user-question-api.test.ts
@@ -122,6 +122,47 @@ describe("AskUserQuestion hook API", () => {
     expect(stored?.questions[0]?.options).toHaveLength(3);
   });
 
+  it("keeps Cyrillic question text intact from the raw UTF-8 body to the read endpoint", async () => {
+    // Regression for issue #130: the overlay showed every Cyrillic character as
+    // "?". The POSIX hook POSTs the payload verbatim (curl --data-binary), so
+    // the server must decode the raw bytes as UTF-8 end to end.
+    const question = "Какой вариант выбрать?";
+    const header = "Следующий шаг";
+    const label = "Завершить текущую задачу";
+    const description = "Доделать изменённый файл — u1d1–5";
+    const payload = {
+      hook_event_name: "PreToolUse",
+      session_id: SESSION_ID,
+      tool_name: "AskUserQuestion",
+      tool_use_id: TOOL_USE_ID,
+      tool_input: {
+        questions: [
+          { question, header, multiSelect: false, options: [{ label, description }] },
+        ],
+      },
+    };
+
+    const res = await handleApiRequest(
+      authed(`/api/hooks/claude?taskId=${encodeURIComponent(taskId)}`, {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: new TextEncoder().encode(JSON.stringify(payload)),
+      }),
+    );
+    expect(res?.status).toBe(200);
+
+    expect(getPendingQuestion(taskId)?.questions).toEqual([
+      { question, header, multiSelect: false, options: [{ label, description }] },
+    ]);
+
+    const read = await getQuestion(taskId);
+    const body = (await read?.json()) as {
+      question: { questions: Array<{ question: string; header?: string; options: Array<{ label: string; description?: string }> }> } | null;
+    };
+    expect(body.question?.questions[0]).toMatchObject({ question, header });
+    expect(body.question?.questions[0]?.options[0]).toEqual({ label, description });
+  });
+
   it("serves the pending question over the read endpoint", async () => {
     await postAskUserQuestion(taskId);
 
diff --git a/src/shared/agent-hooks.ts b/src/shared/agent-hooks.ts
index 38241869..2894f509 100644
--- a/src/shared/agent-hooks.ts
+++ b/src/shared/agent-hooks.ts
@@ -142,6 +142,20 @@ function buildPosixHookCommand(
   );
 }
 
+// Windows PowerShell 5.1 (what Claude Code's `shell: "powershell"` may run
+// when pwsh isn't installed) is not UTF-8 by default at either end of this
+// script:
+//   - `[Console]::In` decodes stdin with the console code page (OEM/ANSI), so
+//     the UTF-8 hook payload Claude writes is mis-decoded before we even POST;
+//   - a STRING `-Body` is encoded as ISO-8859-1, which replaces every code
+//     point outside Latin-1 (Cyrillic, CJK, emoji, "–") with `?`.
+// Together they turned a Cyrillic AskUserQuestion into a wall of `?` in the
+// native overlay (issue #130). So: read stdin as raw UTF-8 bytes, POST the
+// body as bytes (sent verbatim on both 5.1 and 7), and for injectContext
+// events pass the server's response bytes straight to stdout instead of
+// decoding them (also ISO-8859-1 on 5.1) and re-serializing via
+// ConvertTo-Json — the same verbatim passthrough `curl --data-binary @-`
+// gives the POSIX hook.
 function buildPowerShellHookCommand(
   endpointSlug: string,
   event: string,
@@ -156,19 +170,29 @@ function buildPowerShellHookCommand(
   const continueOutput =
     style === "cursor" ? '; Write-Output \'{"continue":true}\'' : "";
 
-  // injectContext: emit the JSON response to stdout (re-serialized) so Claude can
-  // inject it; otherwise pipe to Out-Null. Both swallow errors (fail-soft).
+  const request =
+    "Invoke-WebRequest -UseBasicParsing -Method Post -Uri $url -Headers $headers " +
+    '-Body $body -ContentType "application/json; charset=utf-8" -TimeoutSec 3 -ErrorAction Stop';
+  // injectContext: stream the response bytes to stdout untouched so Claude can
+  // inject them; otherwise discard the response. Both swallow errors (fail-soft)
+  // — but `catch {}` leaves `$?` false, which `-Command` reports as exit code 1,
+  // so the script ends in an explicit `exit 0` (the POSIX hook's `|| true`).
   const invoke = injectContext
-    ? 'try { $resp = Invoke-RestMethod -Method Post -Uri $url -Headers $headers -Body $payload -ContentType "application/json" -TimeoutSec 3 -ErrorAction Stop; if ($resp) { $resp | ConvertTo-Json -Depth 10 -Compress } } catch {}'
-    : 'try { Invoke-RestMethod -Method Post -Uri $url -Headers $headers -Body $payload -ContentType "application/json" -TimeoutSec 3 -ErrorAction Stop | Out-Null } catch {}';
+    ? `try { $r = ${request}; $bytes = $r.RawContentStream.ToArray(); ` +
+      "if ($bytes.Length -gt 0) { $stdout = [Console]::OpenStandardOutput(); " +
+      "$stdout.Write($bytes, 0, $bytes.Length); $stdout.Flush() } } catch {}"
+    : `try { ${request} | Out-Null } catch {}`;
 
   return [
     missingEnv,
-    "$payload = [Console]::In.ReadToEnd()",
+    "$ProgressPreference = 'SilentlyContinue'",
+    "$payload = [System.IO.StreamReader]::new([Console]::OpenStandardInput(), [System.Text.UTF8Encoding]::new($false)).ReadToEnd()",
+    "$body = [System.Text.Encoding]::UTF8.GetBytes($payload)",
     "$taskId = [System.Uri]::EscapeDataString($env:MC_TASK_ID)",
     `$url = "$($env:MC_API_URL)/api/hooks/${endpointSlug}?taskId=$taskId&hookEvent=${eventParam}"`,
     '$headers = @{ Authorization = "Bearer $($env:MC_API_TOKEN)"; "X-Mission-Control-Runtime" = "electron-local" }',
     invoke + continueOutput,
+    "exit 0",
   ].join("; ");
 }