[General] Update check failed with ReleaseNotFound error in restricted/internal network environment

Hi. I installed github-copilot app at my Internal Network pc.

When running the GitHub Copilot App on a PC within a restricted internal business network, the application fails to check for updates and throws a ReleaseNotFound error. It appears that the application is unable to fetch the required release metadata JSON from the remote update endpoint, likely due to network firewalls, proxy environments, or blocked update domains.

The Application hangs on below loading states.

### Logs / Error Message

```bash
(base) deukyun@deukyun-ws:~$ github-copilot
2026-06-15T02:39:57.182855Z INFO github_app: GitHub Copilot app started pid=22634 version=0.2.32 log_file=/home/deukyun/.copilot/logs/github-app.22634.log
2026-06-15T02:39:57.397994Z INFO github_app::database: opening database db_path="/home/deukyun/.copilot/data.db"
2026-06-15T02:39:58.226172Z DEBUG github_app::telemetry: Runtime telemetry service initialized
2026-06-15T02:39:58.626957Z INFO github_app: Skipping git credential trampoline broker (bundled_git experiment off)
2026-06-15T02:40:00.076892Z INFO github_app: Resolved app skills directory path=/home/deukyun/.local/share/com.github.githubapp/app-skills
2026-06-15T02:40:00.078184Z INFO github_app: Resolved terminal integration directory path=/tmp/.mount_githubKEjpan/usr/lib/GitHub Copilot/terminal-integration
2026-06-15T02:40:00.079004Z INFO github_app: Resolved Foundry native library directory path=/tmp/.mount_githubKEjpan/usr/lib/GitHub Copilot
2026-06-15T02:40:00.080101Z INFO github_app: Discovered bundled Copilot SDK directory (will be passed to the CLI as extensionSdkPath once the SDK exposes that option; until then the CLI uses its built-in SDK) path=/tmp/.mount_githubKEjpan/usr/lib/GitHub Copilot/copilot-sdk
2026-06-15T02:40:00.122869Z INFO github_app::git: resolved git env binary=git embedded_git_in_use=false path=/home/deukyun/.npm-global/bin:/usr/local/python3.14/bin:/home/deukyun/.local/share/reflex/bun/bin:/home/deukyun/bin:/usr/bin:/home/deukyun/.kubectx:/home/deukyun/anaconda3/bin:/home/deukyun/anaconda3/condabin:/home/deukyun/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/deukyun/.local/share/JetBrains/Toolbox/scripts:/home/deukyun/.local/share/coursier/bin:/home/deukyun/Work/scala/scala-2.12.2/bin:/home/deukyun/Work/sbt/sbt/bin:/home/deukyun/Work/istio-1.25.1/bin
2026-06-15T02:40:00.122955Z DEBUG github_app::git: trampoline env not attached to git_command; using system git's own credential helpers global_present=false sidecar_present=false
2026-06-15T02:40:00.193112Z INFO github_app::notification_linux: Linux notification support initialized
2026-06-15T02:40:00.248027Z INFO github_app::git: Detected git version at startup version=git version 2.34.1 binary=git embedded_git_in_use=false bundled_version="2.53.0-3"
2026-06-15T02:40:00.752797Z INFO github_app::websocket: WebSocket server listening on ws://127.0.0.1:44279
2026-06-15T02:40:00.761926Z INFO github_app::websocket: wrote run file value=44279 path=/home/deukyun/.copilot/run/ws.port
2026-06-15T02:40:00.762949Z INFO github_app::websocket: wrote WebSocket auth token path=/home/deukyun/.copilot/run/ws.token
2026-06-15T02:40:00.762986Z DEBUG github_app::platform::keep_awake: Keep-awake manager initialised
2026-06-15T02:40:00.773144Z INFO github_app::scheduler: Scheduler starting for workflows and session automations...
2026-06-15T02:40:01.146009Z INFO github_app::platform::health: Detected Copilot CLI version at startup version=Copilot binary version: 1.0.61 source=Some(Bundled) path="/home/deukyun/.cache/github-copilot-sdk/cli/1.0.61/copilot" bundled_version="1.0.61"
2026-06-15T02:40:06.201817Z DEBUG github_app::websocket: returning websocket info port=44279 token_len=43
2026-06-15T02:40:06.437132Z INFO github_app::websocket: wrote run file value=44279 path=/home/deukyun/.copilot/run/ws.port
2026-06-15T02:40:06.437422Z INFO github_app::websocket: wrote WebSocket auth token path=/home/deukyun/.copilot/run/ws.token
2026-06-15T02:40:07.494021Z DEBUG github_app::platform::updater: Checking for updates current_version="0.2.32"
2026-06-15T02:40:07.504163Z DEBUG github_app::platform::updater: No github.com account signed in; fetching update manifest anonymously. Users with only GHEC accounts will not receive authenticated rate-limit headroom and rely on the public release repo.
2026-06-15T02:40:08.040907Z DEBUG github_app::platform::updater: Falling back to alternate update release source owner="github" repo="github-app" fallback_owner="github" fallback_repo="app" error=Sign in to GitHub to check for app updates
2026-06-15T02:40:08.302196Z DEBUG github_app::websocket: returning websocket info port=44279 token_len=43
2026-06-15T02:40:08.586463Z DEBUG github_app::platform::updater: No GitHub token available for authenticated update checks
2026-06-15T02:40:08.587065Z DEBUG github_app::platform::updater: Building updater has_auth_token=false
2026-06-15T02:40:08.663618Z ERROR tauri_plugin_updater::updater: update endpoint did not respond with a successful status code
2026-06-15T02:40:08.664009Z ERROR github_app::platform::updater: Update check failed error=Could not fetch a valid release JSON from the remote error_debug=ReleaseNotFound
2026-06-15T02:40:09.947388Z DEBUG github_app::websocket: returning websocket info port=44279 token_len=43
2026-06-15T02:40:13.783449Z DEBUG github_app::websocket: returning websocket info port=44279 token_len=43
2026-06-15T02:40:14.294759Z DEBUG github_app::websocket: returning websocket info port=44279 token_len=43
2026-06-15T02:40:15.360013Z INFO github_app::websocket: wrote run file value=44279 path=/home/deukyun/.copilot/run/ws.port
```

```
2026-06-15T02:40:08.663618Z ERROR tauri_plugin_updater::updater: update endpoint did not respond with a successful status code
2026-06-15T02:40:08.664009Z ERROR github_app::platform::updater: Update check failed error=Could not fetch a valid release JSON from the remote error_debug=ReleaseNotFound
```

### Environment

OS; Ubuntu 22.04
App Version: v0.2.32

### Requests

To resolve this issue in our restricted internal network, could you please provide guidance on either of the following solutions?

1. **Firewall Whitelist Domains:**
* What are the exact domains, IP ranges, or endpoints that the GitHub Copilot App (and the `tauri_plugin_updater`) attempts to connect to for update checks?
* (e.g., Specific GitHub API endpoints or custom release servers that we need to allow through our corporate firewall/proxy.)

2. **Workaround to Bypass Update Checks:**
* Is there an environment variable, a config file setting (e.g., `config.json`), or a CLI flag available to completely disable the automatic update check on startup?
* If not, is there a way to manually configure proxy settings (`HTTP_PROXY` / `HTTPS_PROXY`) specifically for this application's updater plugin?