diff --git a/docs/architecture/packaging.md b/docs/architecture/packaging.md
index 973812e00d..3c24a4484d 100644
--- a/docs/architecture/packaging.md
+++ b/docs/architecture/packaging.md
@@ -73,7 +73,7 @@ The release workflow runs the three scripts directly. Without the parser pack, D
 
 - `scripts/opencode/stage.mjs`, which `build:opencode` runs, stages opencode `1.18.34` and ripgrep `15.1.0` into `electron/opencode/`, each archive checked against its SHA-256 in `scripts/opencode/pins.mjs`. On x64 it takes opencode's `-baseline` build, which opencode compiles without AVX2. The release archives carry only the executable, so opencode's licence comes from its tag, also pinned; ripgrep's three licence files ship in `opencode/ripgrep/`. It runs `opencode --version` and `rg --version` from the staged folder before it swaps the folder into place, and restages when the staged opencode reports another version. The Linux executable needs glibc 2.17 and no libstdc++. It stages only when `scripts/opencode/enabled.mjs` says opencode is on, which is off until a model passes the agent test and `SURFSENSE_LOCAL_OPENCODE_ENABLED=1` overrides; off, it removes an earlier stage, so neither `pnpm dev` nor an installer carries one.
 
-`pnpm dist` in `electron/` runs every staging step before `electron-builder`, the native runtimes first, so a missing toolchain stops it before the frontend and the Python binaries are built. It stages sd.cpp and audio.cpp with `--strict`, so an installer never ships without them; `predev` does not, so dev runs without a toolchain.
+`pnpm dist` in `electron/` runs every staging step before `electron-builder`, the native runtimes first, so a missing toolchain stops it before the frontend and the Python binaries are built. It stages sd.cpp and audio.cpp with `--strict`, so an installer never ships without them; `predev` does not, so dev runs without a toolchain. On Windows, the rename that swaps each stage into place waits up to a minute while another process still has a file in it open, such as a Windows service reading an executable the script just ran.
 
 `frontend/` and `electron/` each pin their pnpm in `packageManager` (`pnpm@11.27.1`), which pnpm switches to locally and the desktop workflows read through `package_json_file`. The repository root's `packageManager` is the web app's, `pnpm@10.26.0`, and does not apply here.
 
diff --git a/surfsense_local/electron/scripts/audiocpp/stage.mjs b/surfsense_local/electron/scripts/audiocpp/stage.mjs
index 40090d7b54..770e71218e 100644
--- a/surfsense_local/electron/scripts/audiocpp/stage.mjs
+++ b/surfsense_local/electron/scripts/audiocpp/stage.mjs
@@ -14,6 +14,7 @@ import { stageEspeak } from "./espeak.mjs"
 import { copyMsvcRuntime } from "../msvc-runtime.mjs"
 import { NotStaged, notStaged } from "../not-staged/message.mjs"
 import { packageManager } from "../not-staged/package-manager.mjs"
+import { renameWhenUnlocked } from "../windows-locks/rename-when-unlocked.mjs"
 import { TAG } from "./pins.mjs"
 import { copyServerFiles, SERVER } from "./server-files.mjs"
 import { unpackUpstream } from "./upstream-archive.mjs"
@@ -85,7 +86,7 @@ async function main() {
     rmSync(backup, { recursive: true, force: true })
     if (existsSync(OUT)) renameSync(OUT, backup)
     try {
-      renameSync(stage, OUT)
+      await renameWhenUnlocked(stage, OUT)
     } catch (error) {
       if (existsSync(backup)) renameSync(backup, OUT)
       throw error
diff --git a/surfsense_local/electron/scripts/fetch-llamacpp.mjs b/surfsense_local/electron/scripts/fetch-llamacpp.mjs
index 73f2d5d732..7611b84cc5 100644
--- a/surfsense_local/electron/scripts/fetch-llamacpp.mjs
+++ b/surfsense_local/electron/scripts/fetch-llamacpp.mjs
@@ -33,6 +33,8 @@ import { tmpdir } from "node:os"
 import { basename, dirname, join } from "node:path"
 import { fileURLToPath } from "node:url"
 
+import { renameWhenUnlocked } from "./windows-locks/rename-when-unlocked.mjs"
+
 export const BUILD = "b11050"
 const BASE = `https://github.com/ggml-org/llama.cpp/releases/download/${BUILD}`
 const HERE = fileURLToPath(new URL(".", import.meta.url))
@@ -189,7 +191,7 @@ async function main() {
     rmSync(backup, { recursive: true, force: true })
     if (existsSync(OUT)) renameSync(OUT, backup)
     try {
-      renameSync(stage, OUT)
+      await renameWhenUnlocked(stage, OUT)
     } catch (error) {
       if (existsSync(backup)) renameSync(backup, OUT)
       throw error
diff --git a/surfsense_local/electron/scripts/opencode/stage.mjs b/surfsense_local/electron/scripts/opencode/stage.mjs
index 18d908777a..23f233dc46 100644
--- a/surfsense_local/electron/scripts/opencode/stage.mjs
+++ b/surfsense_local/electron/scripts/opencode/stage.mjs
@@ -8,6 +8,7 @@ import { basename, join } from "node:path"
 import { fileURLToPath } from "node:url"
 
 import { download, unpack } from "../pinned-download.mjs"
+import { renameWhenUnlocked } from "../windows-locks/rename-when-unlocked.mjs"
 import { opencodeEnabled } from "./enabled.mjs"
 import { HOSTS, OPENCODE_LICENCE, RIPGREP_VERSION, VERSION } from "./pins.mjs"
 
@@ -103,7 +104,7 @@ async function main() {
     rmSync(backup, { recursive: true, force: true })
     if (existsSync(OUT)) renameSync(OUT, backup)
     try {
-      renameSync(stage, OUT)
+      await renameWhenUnlocked(stage, OUT)
     } catch (error) {
       if (existsSync(backup)) renameSync(backup, OUT)
       throw error
diff --git a/surfsense_local/electron/scripts/sdcpp/stage.mjs b/surfsense_local/electron/scripts/sdcpp/stage.mjs
index e5b864cabe..db0f6236eb 100644
--- a/surfsense_local/electron/scripts/sdcpp/stage.mjs
+++ b/surfsense_local/electron/scripts/sdcpp/stage.mjs
@@ -13,6 +13,7 @@ import { copyMsvcRuntime, visualStudio } from "../msvc-runtime.mjs"
 import { NotStaged, notStaged } from "../not-staged/message.mjs"
 import { packageManager } from "../not-staged/package-manager.mjs"
 import { VISUAL_STUDIO } from "../not-staged/tools.mjs"
+import { renameWhenUnlocked } from "../windows-locks/rename-when-unlocked.mjs"
 import { compile, missingToolchain } from "./compile.mjs"
 import { TAG } from "./pins.mjs"
 import { copyServerFiles, SERVER } from "./server-files.mjs"
@@ -87,7 +88,7 @@ async function main() {
     rmSync(backup, { recursive: true, force: true })
     if (existsSync(OUT)) renameSync(OUT, backup)
     try {
-      renameSync(stage, OUT)
+      await renameWhenUnlocked(stage, OUT)
     } catch (error) {
       if (existsSync(backup)) renameSync(backup, OUT)
       throw error
diff --git a/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.mjs b/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.mjs
new file mode 100644
index 0000000000..9ee602fa21
--- /dev/null
+++ b/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.mjs
@@ -0,0 +1,22 @@
+// A rename that waits out Windows holding a file open inside the folder being renamed.
+import { renameSync } from "node:fs"
+import { setTimeout as sleep } from "node:timers/promises"
+
+// Only Windows answers this way for a file another process holds open; elsewhere they are real permission errors.
+const LOCKED = new Set(["EPERM", "EACCES", "EBUSY"])
+
+/** Rename `from` to `to`, retrying while another process holds a file in it, such as a Windows
+ * service reading a binary we just ran. 60 s by default: the window graceful-fs waits for the same lock. */
+export async function renameWhenUnlocked(from, to, { rename = renameSync, timeoutMs = 60_000, platform = process.platform } = {}) {
+  const start = Date.now()
+  for (let attempt = 1; ; attempt++) {
+    try {
+      return rename(from, to)
+    } catch (error) {
+      if (platform !== "win32" || !LOCKED.has(error.code) || Date.now() - start >= timeoutMs) throw error
+      if (attempt === 1) console.warn(`rename of ${from} blocked (${error.code}), retrying for up to ${timeoutMs / 1000} s`)
+      await sleep(Math.min(10 * attempt, 100))
+    }
+  }
+}
+
diff --git a/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.test.mjs b/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.test.mjs
new file mode 100644
index 0000000000..0cc92232b4
--- /dev/null
+++ b/surfsense_local/electron/scripts/windows-locks/rename-when-unlocked.test.mjs
@@ -0,0 +1,38 @@
+import assert from "node:assert/strict"
+import test from "node:test"
+
+import { renameWhenUnlocked } from "./rename-when-unlocked.mjs"
+
+/** A stand-in for renameSync that fails with each code in turn, then succeeds. */
+function renameFailingWith(...codes) {
+  return () => {
+    const code = codes.shift()
+    if (code) throw Object.assign(new Error(`rename failed: ${code}`), { code })
+  }
+}
+
+test("a rename that fails for another reason is rethrown without a retry", async () => {
+  await assert.rejects(renameWhenUnlocked("stage", "out", { rename: renameFailingWith("ENOENT"), platform: "win32" }), {
+    code: "ENOENT",
+  })
+})
+
+test("a rename Windows refuses twice goes through on the third try", async () => {
+  await assert.doesNotReject(
+    renameWhenUnlocked("stage", "out", { rename: renameFailingWith("EPERM", "EPERM"), platform: "win32" }),
+  )
+})
+
+test("a rename locked for longer than the time limit gives up and rethrows EPERM", async () => {
+  const lockedFor24Tries = renameFailingWith(...Array(24).fill("EPERM"))
+  await assert.rejects(renameWhenUnlocked("stage", "out", { rename: lockedFor24Tries, timeoutMs: 50, platform: "win32" }), {
+    code: "EPERM",
+  })
+})
+
+test("off Windows, a refused rename is rethrown without a retry", async () => {
+  await assert.rejects(
+    renameWhenUnlocked("stage", "out", { rename: renameFailingWith("EPERM"), platform: "linux" }),
+    { code: "EPERM" },
+  )
+})