fix: enable emulator keyboard in Nix dev shell (#1193)

README.md

@@ -91,6 +91,21 @@ If Hermes Mobile is useful to you, consider supporting its development on [Ko-fi
 
 _Note: For release builds, ensure keystore environment variables (`KEYSTORE_PATH`, `KEYSTORE_PASSWORD`, `KEY_ALIAS`, `KEY_PASSWORD`) are configured, or let the GitHub Actions release workflow handle it on tag push (`v*`)._
 
+### Nix emulator
+
+The Nix development shell enables physical keyboard input in an existing
+`hermes_dev` AVD configuration. It respects `ANDROID_AVD_HOME` and
+`ANDROID_USER_HOME`, defaulting to `~/.android/avd`.
+
+Close any running emulator, then cold boot once to apply the setting:
+
+```bash
+nix develop --command emulator -avd hermes_dev -no-snapshot-load
+```
+
+Subsequent launches can omit `-no-snapshot-load`. Create the `hermes_dev` AVD
+first if it does not exist; the shell does not create one.
+
 ---
 
 ## Authentication

flake.nix

@@ -93,6 +93,17 @@
             # Writable gradle home
             mkdir -p "$GRADLE_USER_HOME"
 
+            # Enable host keyboard input for the project's existing AVD.
+            hermesAvdConfig="''${ANDROID_AVD_HOME:-''${ANDROID_USER_HOME:-$HOME/.android}/avd}/hermes_dev.avd/config.ini"
+            if [ -f "$hermesAvdConfig" ]; then
+              if ${pkgs.gnugrep}/bin/grep -q '^hw\.keyboard[[:space:]]*=' "$hermesAvdConfig"; then
+                ${pkgs.gnused}/bin/sed -i 's/^hw\.keyboard[[:space:]]*=.*/hw.keyboard=yes/' "$hermesAvdConfig"
+              else
+                printf '\nhw.keyboard=yes\n' >> "$hermesAvdConfig"
+              fi
+            fi
+            unset hermesAvdConfig
+
             # ADB Screen Resolution Aliases
             alias avd-phone='adb shell wm size 1440x3120 && adb shell wm density 500'
             alias avd-phone-fhd='adb shell wm size 1080x2400 && adb shell wm density 420'