diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 747ec5e10..a7973b710 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -285,9 +285,12 @@ jobs:
             # and never launch a Playwright browser, so no `playwright
             # install`. The runner image ships Electron's shared libraries and
             # xvfb; fail fast with a clear message if an image update drops one.
+            # pnpm skips Electron's postinstall, so download the binary first;
+            # otherwise ldd sees no file and the check passes vacuously.
             - name: Check Electron runtime dependencies
               run: |
                   command -v xvfb-run || { echo "::error::xvfb-run is missing on the runner"; exit 1; }
+                  node tools/testing/ensure-electron-binary.mjs || { echo "::error::Electron binary download failed"; exit 1; }
                   missing="$(ldd node_modules/electron/dist/electron | grep 'not found' || true)"
                   if [ -n "$missing" ]; then
                       echo "::error::Electron is missing shared libraries:"
@@ -368,6 +371,15 @@ jobs:
             - name: Install dependencies
               run: pnpm install --frozen-lockfile
 
+            # pnpm skips Electron's postinstall (it is not in
+            # onlyBuiltDependencies), so the binary is fetched on the first
+            # require('electron'). Specs that run SQLite under
+            # ELECTRON_RUN_AS_NODE resolve it that way while Tier A projects
+            # run concurrently, and one exec'ing it mid-extraction fails with
+            # ETXTBSY. Download and verify it once, before any test starts.
+            - name: Download Electron binary
+              run: node tools/testing/ensure-electron-binary.mjs
+
             - name: Validate agent guidance
               run: pnpm run agents:validate
 
diff --git a/docs/architecture/validation-map.md b/docs/architecture/validation-map.md
index ff50576c9..5a9a5f9e6 100644
--- a/docs/architecture/validation-map.md
+++ b/docs/architecture/validation-map.md
@@ -107,6 +107,18 @@ with `diagnostics: false`); `isolatedModules`-incompatible syntax such as a
 type re-export without `export type` still fails at load time, and spec type
 errors are caught by `typecheck:spec` (see Unit And Type Checks).
 
+Some `electron-backend` and `database` specs run SQLite code in the Electron
+binary under `ELECTRON_RUN_AS_NODE`, resolving it with `require('electron')`.
+pnpm does not run Electron's postinstall (`electron` is deliberately absent from
+`onlyBuiltDependencies`, see [workspace shell](workspace-shell.md)), so the
+first `require` downloads and extracts the binary. With projects and Jest
+workers in parallel, one process can exec it while another is still extracting
+it (`spawnSync … ETXTBSY` on Linux). `coverage:unit:ci` and a CI step right
+after `pnpm install` therefore run `tools/testing/ensure-electron-binary.mjs`
+first, which downloads the binary once and fails unless it runs and reports
+the pinned version. In a fresh worktree, run it before starting several of
+these specs at once by other means.
+
 In CI, a pull request skips the Tier A suite (and the merged-coverage upload)
 when every changed file is outside Tier A test inputs:
 `tools/coverage/unit-coverage-scope.mjs` holds the allowlist (Markdown, `docs/`,
diff --git a/package.json b/package.json
index c5c2fb931..e25fad65c 100644
--- a/package.json
+++ b/package.json
@@ -45,7 +45,7 @@
         "styles:inputs:check": "node tools/nx/check-stylesheet-inputs.mjs",
         "styles:inputs:validate": "pnpm run styles:inputs:test && pnpm run styles:inputs:check",
         "coverage:tools:test": "node --test tools/coverage/coverage-integrity.test.mjs tools/coverage/e2e-shard-reports.test.mjs tools/coverage/coverage-run-pool.test.mjs tools/coverage/unit-coverage-scope.test.mjs",
-        "coverage:unit:ci": "node tools/coverage/run-tier-a-coverage.mjs",
+        "coverage:unit:ci": "node tools/testing/ensure-electron-binary.mjs && node tools/coverage/run-tier-a-coverage.mjs",
         "coverage:merge": "node tools/coverage/merge-coverage.mjs",
         "coverage:health": "node tools/coverage/coverage-health.mjs",
         "coverage:policy:check": "node tools/coverage/check-coverage-policy.mjs",
diff --git a/tools/testing/ensure-electron-binary.mjs b/tools/testing/ensure-electron-binary.mjs
new file mode 100644
index 000000000..1f0946d34
--- /dev/null
+++ b/tools/testing/ensure-electron-binary.mjs
@@ -0,0 +1,62 @@
+#!/usr/bin/env node
+
+// Downloads the Electron binary once and proves it runs, before anything
+// spawns it concurrently.
+//
+// pnpm does not run Electron's postinstall (it is not in
+// `onlyBuiltDependencies`), so `pnpm install` leaves no binary behind and
+// `require('electron')` downloads and extracts it on first use. Unit specs
+// that execute SQLite code under `ELECTRON_RUN_AS_NODE` resolve it that way,
+// and Tier A projects and Jest workers run in parallel: one process can exec
+// the binary while another is still extracting it (ETXTBSY on Linux, clobbered
+// framework symlinks on macOS). Running this first leaves nothing to download.
+//
+// Usage: node tools/testing/ensure-electron-binary.mjs
+
+import { execFileSync } from 'node:child_process';
+import { createRequire } from 'node:module';
+import process from 'node:process';
+
+const require = createRequire(import.meta.url);
+const { version } = require('electron/package.json');
+
+let electronPath;
+try {
+    electronPath = require('electron');
+} catch (error) {
+    console.error(
+        `Electron ${version} binary download failed: ${error.message}`
+    );
+    process.exit(1);
+}
+
+let reported;
+try {
+    reported = execFileSync(
+        electronPath,
+        ['-e', 'process.stdout.write(process.versions.electron)'],
+        {
+            encoding: 'utf8',
+            // The child's stderr (e.g. a dyld or loader error) goes straight
+            // to the log instead of being repeated in the message below.
+            stdio: ['ignore', 'pipe', 'inherit'],
+            env: { ...process.env, ELECTRON_RUN_AS_NODE: '1' },
+            timeout: 60_000,
+        }
+    ).trim();
+} catch (error) {
+    console.error(
+        `Electron binary at ${electronPath} does not run (${error.code ?? `exit ${error.status}`}). ` +
+            'If an interrupted download left a partial copy, delete node_modules/electron/dist and path.txt, then rerun.'
+    );
+    process.exit(1);
+}
+
+if (reported !== version) {
+    console.error(
+        `Electron binary at ${electronPath} reports ${reported || 'no version'}, expected ${version}.`
+    );
+    process.exit(1);
+}
+
+console.log(`Electron ${version} binary ready at ${electronPath}`);