fix(control): screen recordings are private: the segment folder and the recordings folder are owner only

src/control/commands/capture-session.ts

@@ -1,4 +1,5 @@
 import { randomUUID } from "node:crypto";
+import { chmod, mkdir } from "node:fs/promises";
 import { withInterrupt } from "@genesiscz/utils/cli/interrupt";
 import { SafeJSON } from "@genesiscz/utils/json";
 import { logger, out } from "@genesiscz/utils/logger";
@@ -180,6 +181,9 @@ export function registerCaptureSessionCommands(capture: Command): void {
                     throw new Error("Nothing on screen to record.");
                 }
 
+                // The default output and every session folder live here, so the folder is owner only.
+                await mkdir(recordingsDir(), { recursive: true, mode: 0o700 });
+                await chmod(recordingsDir(), 0o700);
                 session = new RecordingSession({
                     target,
                     directory: recordingsDir(`session-${randomUUID()}`),

src/control/lib/recording-session.test.ts

@@ -288,6 +288,33 @@ describe("RecordingSession", () => {
         expect(await recording.finished).toBe("discarded");
     });
 
+    it("keeps its segment folder private, also when the folder already exists with wider permissions", async () => {
+        for (const existing of [false, true]) {
+            const directory = join(root, existing ? "existing" : "new");
+            if (existing) {
+                await mkdir(directory, { mode: 0o755 });
+            }
+
+            const { recorder } = fakeRecorder();
+            const recording = new RecordingSession({
+                target: finder,
+                directory,
+                output: join(root, "private.mp4"),
+                recorder,
+                join: async () => ({ durationMs: 0 }),
+                emit: () => {},
+                now: () => clock,
+                tickMs: 0,
+                slowStartMs: 0,
+            });
+            await recording.start();
+
+            expect((await fs.stat(directory)).mode & 0o777).toBe(0o700);
+            await recording.command({ cmd: "discard" });
+            expect(await recording.finished).toBe("discarded");
+        }
+    });
+
     it("a failed join keeps a movie already at the output and leaves no temporary file", async () => {
         const { recorder } = fakeRecorder();
         await writeFile(join(root, "out.mp4"), "previous movie");

src/control/lib/recording-session.ts

@@ -1,6 +1,6 @@
 import { randomUUID } from "node:crypto";
 import { existsSync } from "node:fs";
-import { copyFile, mkdir, rename, rm, unlink } from "node:fs/promises";
+import { chmod, copyFile, mkdir, rename, rm, unlink } from "node:fs/promises";
 import { dirname, join } from "node:path";
 import { SafeJSON } from "@genesiscz/utils/json";
 import { logger } from "@genesiscz/utils/logger";
@@ -198,7 +198,9 @@ export class RecordingSession {
     start(): Promise<void> {
         return this.enqueue(async () => {
             try {
-                await mkdir(this.options.directory, { recursive: true });
+                // Screen recordings are private: owner only. `mode` covers a new folder, chmod an existing one.
+                await mkdir(this.options.directory, { recursive: true, mode: 0o700 });
+                await chmod(this.options.directory, 0o700);
             } catch (error) {
                 log.warn({ error }, "could not create recording directory");
                 this.end("failed");