This project is designed for use on one PC. The local API has no general-purpose user authentication and is not intended for the internet, a LAN, port forwarding, reverse proxies, or tunnels. In addition to loopback binding, every HTTP request must carry a loopback Host; browser-origin POST requests are accepted only from a Chrome extension origin, while native same-PC clients may omit Origin. POST bodies must use application/json and are limited to 32 MiB.

• The default bind address is 127.0.0.1.
• Only 127.0.0.1, localhost, and ::1 are accepted as configured hosts and HTTP Host values.
• 0.0.0.0, LAN addresses, external addresses, and non-loopback HTTP Host values are rejected.
• publicBaseUrl must also be a loopback HTTP URL. There is no remote-access override.
• Normal web-page origins such as https://example.com, https://chatgpt.com, null, and loopback web pages cannot invoke POST mutation endpoints.
• Cross-origin preflight requests from normal web pages are rejected and the server does not emit permissive CORS headers.
• Normal API responses do not expose user-specific absolute filesystem paths such as the local model-cache directory.

The extension sends only the ChatGPT response selected by the current user action: a new response preview detected after Auto was enabled, or the chunk selected by Next, Regen, or Replay. It does not upload the conversation to an external service.

Generated audio is stored under local-api/runtime/audio/ and may remain there until retention cleanup or the user deletes it. Reference audio, its transcription text, local configuration, logs, models, and caches are local files. For crash/reconnect recovery, the local runtime state can also contain recent assistant-response chunks, playback queue items, and transcript delivery events until they are acknowledged. Raw microphone recordings and a long-term STT transcript history are not stored. The privacy-safe structured runtime event log excludes prompt/reply bodies and absolute paths, rotates at 2 MiB, and keeps at most two backup generations. These local files are excluded from the public repository, but users remain responsible for deleting their own runtime data when it is no longer needed.

extension/manifest.json requests:

• storage: save extension settings and recover browser-side playback state after a Manifest V3 service-worker restart.
• scripting: restore the content scripts in already-open ChatGPT tabs when the service worker or local API reconnects.
• alarms: wake the Manifest V3 service worker at a low-frequency recovery interval.
• Page access to https://chatgpt.com/* and https://chat.openai.com/*: detect assistant responses selected for reading, update tab status, and deliver an approved local transcript to the ChatGPT composer.
• Host access to http://127.0.0.1:8717/* and http://localhost:8717/*: call the local health, speech, control-panel, reference-voice, and generated-audio endpoints.

No cloud TTS endpoint is configured by this project.

Do not publish vulnerability details, API keys, reference audio, ChatGPT exports, local configuration, or logs in a public Issue. Use GitHub Security Advisories for this repository and include a minimal reproduction and the affected revision.