[codex] Fix Read Aloud setup fallback readiness

linux-features/read-aloud-mcp/README.md

@@ -6,7 +6,7 @@ This feature stages a separate `read-aloud` Codex plugin with a native Rust MCP
 server. It does not enable microphone input or conversation mode. The first MCP
 surface is intentionally small:
 
-- `doctor` reports whether Kokoro, a custom command, or explicit native fallback
+- `doctor` reports whether Kokoro, a custom command, or native fallback
   is available.
 - `read_aloud` speaks text only when the user or agent explicitly asks for it.
 - `stop` interrupts playback started by the MCP server.
@@ -63,10 +63,12 @@ The MCP server reads the same overrides as the UI feature:
 - `CODEX_LINUX_READ_ALOUD_KOKORO_VOICE`
 - `CODEX_LINUX_READ_ALOUD_KOKORO_SPEED`
 - `CODEX_LINUX_READ_ALOUD_KOKORO_LANG`
-- `CODEX_LINUX_READ_ALOUD_NATIVE_FALLBACK=1`
+- `CODEX_LINUX_READ_ALOUD_NATIVE_FALLBACK=0`
 
-Native `spd-say` / `espeak-ng` fallback stays disabled unless explicitly
-requested because the voice quality is usually worse than Kokoro.
+Native `spd-say` / `espeak-ng` fallback is available by default after this
+opt-in MCP plugin is enabled, but Kokoro remains preferred. Set
+`CODEX_LINUX_READ_ALOUD_NATIVE_FALLBACK=0` to disable the machine voice
+fallback.
 
 ## Validate
 

linux-features/read-aloud/README.md

@@ -123,12 +123,14 @@ cleaned response text to stdin:
 CODEX_LINUX_READ_ALOUD_COMMAND="/path/to/tts-stdin-command" codex-desktop
 ```
 
-System TTS fallbacks are disabled by default because `spd-say` and `espeak-ng`
-are widely available but usually unpleasant. Enable them explicitly only when
-that tradeoff is acceptable:
+When Kokoro is not ready, Read Aloud can fall back to system TTS through
+`spd-say` or `espeak-ng`. This fallback is enabled by default only after the
+user has opted into the Read Aloud feature/runtime; Kokoro remains the preferred
+backend when it is available. Disable the native fallback if the machine voice
+is not acceptable:
 
 ```bash
-CODEX_LINUX_READ_ALOUD_NATIVE_FALLBACK=1 codex-desktop
+CODEX_LINUX_READ_ALOUD_NATIVE_FALLBACK=0 codex-desktop
 ```
 
 The handler never invokes a shell for response text.

linux-features/read-aloud/install-kokoro-runtime.sh

@@ -33,14 +33,16 @@ download_file() {
     rm -f "$tmp"
 
     if command -v curl >/dev/null 2>&1; then
-        curl --fail --location --show-error --output "$tmp" "$url"
+        curl --fail --location --show-error --user-agent "codex-desktop-read-aloud" --output "$tmp" "$url"
     elif command -v wget >/dev/null 2>&1; then
-        wget --output-document "$tmp" "$url"
+        wget --user-agent="codex-desktop-read-aloud" --output-document "$tmp" "$url"
     else
         "$python_bin" - "$url" "$tmp" <<'PY'
 import sys
 import urllib.request
-urllib.request.urlretrieve(sys.argv[1], sys.argv[2])
+request = urllib.request.Request(sys.argv[1], headers={"User-Agent": "codex-desktop-read-aloud"})
+with urllib.request.urlopen(request) as response, open(sys.argv[2], "wb") as output:
+    output.write(response.read())
 PY
     fi