chore(youtube-auth): load client_id/secret from env at build time

.github/workflows/release.yml

@@ -41,6 +41,19 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
+      - name: Verify YouTube OAuth secrets are present
+        env:
+          GOOGLE_CLIENT_ID: ${{ secrets.GOOGLE_CLIENT_ID }}
+          GOOGLE_CLIENT_SECRET: ${{ secrets.GOOGLE_CLIENT_SECRET }}
+        run: |
+          missing=()
+          [ -z "$GOOGLE_CLIENT_ID" ] && missing+=(GOOGLE_CLIENT_ID)
+          [ -z "$GOOGLE_CLIENT_SECRET" ] && missing+=(GOOGLE_CLIENT_SECRET)
+          if [ ${#missing[@]} -ne 0 ]; then
+            echo "::error::Missing required repo secret(s): ${missing[*]}. Set them under Settings → Secrets and variables → Actions."
+            exit 1
+          fi
+
       - uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
 
       - uses: swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # v2.9.1
@@ -74,6 +87,8 @@ jobs:
       - uses: tauri-apps/tauri-action@84b9d35b5fc46c1e45415bdb6144030364f7ebc5 # v0.6.2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GOOGLE_CLIENT_ID: ${{ secrets.GOOGLE_CLIENT_ID }}
+          GOOGLE_CLIENT_SECRET: ${{ secrets.GOOGLE_CLIENT_SECRET }}
         with:
           projectPath: apps/desktop
           tagName: ${{ github.ref_name }}

.gitignore

@@ -20,6 +20,10 @@
 .env
 .env.*
 
+# Secrets — never commit OAuth client secret JSON downloads
+client_secret_*.json
+*.client_secret.json
+
 # OS
 .DS_Store
 Thumbs.db

apps/desktop/src-tauri/build.rs

@@ -1,3 +1,7 @@
 fn main() {
+    // Re-run when the YouTube OAuth credentials change so cached
+    // builds don't bake in stale values from a previous environment.
+    println!("cargo:rerun-if-env-changed=GOOGLE_CLIENT_ID");
+    println!("cargo:rerun-if-env-changed=GOOGLE_CLIENT_SECRET");
     tauri_build::build()
 }

apps/desktop/src-tauri/src/youtube_auth/mod.rs

@@ -37,28 +37,47 @@ pub use tokens::YouTubeTokens;
 
 /// OAuth `client_id` for the registered Prismoid Google application.
 ///
-/// Replace with the real value from your Google Cloud Console "OAuth
-/// 2.0 Client IDs → Desktop app" credential before shipping. The
+/// Sourced from the `GOOGLE_CLIENT_ID` env var at compile time so the
+/// real Desktop client credential never lands in the public repo.
+/// Falls back to a placeholder when the env var is unset *or empty*
+/// (GitHub Actions expands a missing `${{ secrets.X }}` to `""`, and
+/// `option_env!` returns `Some("")` in that case), in which case the
 /// surrounding code paths (start_login → complete_login → exchange)
-/// will all return `AuthError::OAuth("invalid_client")` until this is
-/// set to a registered Desktop client.
+/// all return `AuthError::OAuth("invalid_client")`.
 ///
 /// Per RFC 8252 §8.4 and Google's own docs, this `client_id` is a
 /// public identifier — it appears in browser URLs during the
 /// authorization flow and is bundled in source the same way the
 /// Twitch DCF flow handles `TWITCH_CLIENT_ID` (see ADR 37).
-pub const GOOGLE_CLIENT_ID: &str = "REPLACE_ME.apps.googleusercontent.com";
+pub const GOOGLE_CLIENT_ID: &str = or_placeholder(
+    option_env!("GOOGLE_CLIENT_ID"),
+    "REPLACE_ME.apps.googleusercontent.com",
+);
 
 /// OAuth `client_secret` for the registered Prismoid Google application.
 ///
-/// Google issues a `client_secret` for "Desktop app" credentials and
-/// requires it on the token-exchange POST, but their own
-/// [installed-app docs](https://developers.google.com/identity/protocols/oauth2/native-app)
+/// Sourced from the `GOOGLE_CLIENT_SECRET` env var at compile time.
+/// Empty values are treated as unset (see [`GOOGLE_CLIENT_ID`] for the
+/// rationale). Google issues a `client_secret` for "Desktop app"
+/// credentials and requires it on the token-exchange POST, but their
+/// own [installed-app docs](https://developers.google.com/identity/protocols/oauth2/native-app)
 /// note: *"In this context, the client secret is obviously not treated
 /// as a secret."* PKCE S256 is what cryptographically protects the
 /// flow on a public client; this string is included on the wire only
 /// because Google's endpoint won't accept the request without it.
-pub const GOOGLE_CLIENT_SECRET: &str = "REPLACE_ME";
+pub const GOOGLE_CLIENT_SECRET: &str =
+    or_placeholder(option_env!("GOOGLE_CLIENT_SECRET"), "REPLACE_ME");
+
+/// Returns `env` when it's a non-empty string, otherwise `default`.
+/// Used so a build env var explicitly set to `""` (the GitHub Actions
+/// expansion of a missing secret) is treated as unset rather than
+/// silently embedding empty credentials in the binary.
+const fn or_placeholder(env: Option<&'static str>, default: &'static str) -> &'static str {
+    match env {
+        Some(v) if !v.is_empty() => v,
+        _ => default,
+    }
+}
 
 /// Google OAuth 2.0 authorization endpoint. Hard-coded to the v2
 /// endpoint per Google's [installed-app guide](https://developers.google.com/identity/protocols/oauth2/native-app#step-2-send-a-request-to-googles-oauth-20-server).
@@ -78,3 +97,26 @@ pub const SCOPE_YOUTUBE_READONLY: &str = "https://www.googleapis.com/auth/youtub
 /// Full YouTube scope (read + write + moderation). Required to send
 /// messages and ban/timeout/delete on YouTube live chat.
 pub const SCOPE_YOUTUBE: &str = "https://www.googleapis.com/auth/youtube";
+
+#[cfg(test)]
+mod tests {
+    use super::or_placeholder;
+
+    #[test]
+    fn or_placeholder_uses_env_when_non_empty() {
+        assert_eq!(or_placeholder(Some("value"), "fallback"), "value");
+    }
+
+    #[test]
+    fn or_placeholder_falls_back_when_unset() {
+        assert_eq!(or_placeholder(None, "fallback"), "fallback");
+    }
+
+    #[test]
+    fn or_placeholder_falls_back_when_empty() {
+        // GitHub Actions expands a missing `${{ secrets.X }}` to `""`
+        // and option_env! surfaces that as Some(""). The helper must
+        // treat it as unset so release builds don't embed empty creds.
+        assert_eq!(or_placeholder(Some(""), "fallback"), "fallback");
+    }
+}