Make preview versions monotonic and distinguishable from production

build-app-preview.yml computed its patch number as
`git rev-list --count <latest tag>..HEAD` — the exact formula build-app.yml
itself documents as broken and replaced (#26): a distance from whichever
tag sorts highest, not a counter, so it resets to zero on every release and
previews went backwards (0.4.62 -> 0.4.0) the moment one landed. Ported the
same "one past the highest patch already used" computation build-app.yml
uses for real releases, reading the same tags (including -mac/-win
suffixes), so a preview built right before a release now computes the
exact number that release is about to take — semver already orders
`0.4.12-preview.<sha> < 0.4.12`, so a preview user is offered the release
the moment it ships instead of being silently pinned forever.

The installed preview's reported version was also indistinguishable from
production: the bundle's own version field strips the `-preview.<sha>`
suffix before touching tauri.conf.json/Cargo.toml/package.json, since the
Windows MSI's ProductVersion has no room for one. Rather than risk that
(unverifiable without an actual Windows build), preview builds now bake
the suffix into the binary separately via a TRIPLE_C_BUILD_SUFFIX
build-time env var, and get_app_version() appends it when present — a
production build sets nothing, so this is a no-op there.

Also: added `prerelease` to `GitHubRelease` and filter on it in
check_for_updates (currently a no-op against real data — nothing mirrored
to GitHub is ever prerelease:true — but the updater is no longer
structurally incapable of enforcing a channel split if one is ever made
explicit). And deleted sync-release.yml: workflow_dispatch-only, reading
gitea.event.release.* fields a manual dispatch never populates, so it
could never have actually run; build-app.yml's inline mirror already does
the same job.

Refactored check_for_updates' filtering into a pure, testable pick_update
helper (this file had no tests before), and added tests for it and the
new get_app_version suffix handling.

Fixes #32.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FGjXq6fqtAFHdbhk4f3PfZ

app/src-tauri/src/commands/update_commands.rs

@@ -16,9 +16,27 @@ const REGISTRY_API_BASE: &str =
 const GHCR_TOKEN_URL: &str =
     "https://ghcr.io/token?scope=repository:shadowdao/triple-c-sandbox:pull";
 
+/// `CARGO_PKG_VERSION`, plus a build-time suffix when one was baked in.
+///
+/// The bundle version itself (`tauri.conf.json`, `Cargo.toml`, `package.json`)
+/// is never given a `-preview.<sha>` suffix — `build-app-preview.yml` strips
+/// it before patching those files, because the Windows MSI's `ProductVersion`
+/// is a fixed-width numeric field with no room for one, and nothing here can
+/// verify a change to that without an actual Windows build. `TRIPLE_C_BUILD_SUFFIX`
+/// is the workaround: set as a build-time env var in the preview workflow
+/// only, so `option_env!` bakes it into the binary without the bundle version
+/// ever seeing it. A production build sets nothing, so `option_env!` reads
+/// `None` and this is a no-op — see triple-c#32.
+fn format_app_version(base: &str, build_suffix: Option<&str>) -> String {
+    match build_suffix {
+        Some(suffix) if !suffix.is_empty() => format!("{}-{}", base, suffix),
+        _ => base.to_string(),
+    }
+}
+
 #[tauri::command]
 pub fn get_app_version() -> String {
-    env!("CARGO_PKG_VERSION").to_string()
+    format_app_version(env!("CARGO_PKG_VERSION"), option_env!("TRIPLE_C_BUILD_SUFFIX"))
 }
 
 #[tauri::command]
@@ -51,30 +69,8 @@ pub async fn check_for_updates() -> Result<Option<UpdateInfo>, String> {
         &[".AppImage", ".deb", ".rpm"]
     };
 
-    // Filter releases that have at least one asset matching the current platform
-    let platform_releases: Vec<&GitHubRelease> = releases
-        .iter()
-        .filter(|r| {
-            r.assets.iter().any(|a| {
-                platform_extensions.iter().any(|ext| a.name.ends_with(ext))
-            })
-        })
-        .collect();
-
-    // Find the latest release with a higher semver version
-    let mut best: Option<(&GitHubRelease, (u32, u32, u32))> = None;
-    for release in &platform_releases {
-        if let Some(ver) = parse_semver_from_tag(&release.tag_name) {
-            if ver > current_semver {
-                if best.is_none() || ver > best.unwrap().1 {
-                    best = Some((release, ver));
-                }
-            }
-        }
-    }
-
-    match best {
-        Some((release, _)) => {
+    match pick_update(&releases, current_semver, platform_extensions) {
+        Some(release) => {
             // Only include assets matching the current platform
             let assets = release
                 .assets
@@ -105,6 +101,37 @@ pub async fn check_for_updates() -> Result<Option<UpdateInfo>, String> {
     }
 }
 
+/// Pick the newest available update out of a release list, or `None` if
+/// nothing beats `current_semver`. Pure and synchronous — split out of
+/// `check_for_updates` so the prerelease/platform/version filtering can be
+/// tested without a live HTTP call.
+///
+/// Three filters, all of which must pass: not a prerelease (see the long
+/// comment on `GitHubRelease::prerelease`), at least one asset for this
+/// platform, and a tag that parses as semver *and* is newer than what is
+/// running. A tag that does not parse — a `-preview.<sha>` suffix, most
+/// realistically — is skipped rather than erroring, the same as it always
+/// has been; nothing here changes what an update tag is expected to look
+/// like, only what channel it is allowed to come from.
+fn pick_update<'a>(
+    releases: &'a [GitHubRelease],
+    current_semver: (u32, u32, u32),
+    platform_extensions: &[&str],
+) -> Option<&'a GitHubRelease> {
+    releases
+        .iter()
+        .filter(|r| !r.prerelease)
+        .filter(|r| {
+            r.assets
+                .iter()
+                .any(|a| platform_extensions.iter().any(|ext| a.name.ends_with(ext)))
+        })
+        .filter_map(|r| parse_semver_from_tag(&r.tag_name).map(|ver| (r, ver)))
+        .filter(|(_, ver)| *ver > current_semver)
+        .max_by_key(|(_, ver)| *ver)
+        .map(|(r, _)| r)
+}
+
 /// Parse a semver string like "0.2.5" -> (0, 2, 5)
 fn parse_semver(version: &str) -> Option<(u32, u32, u32)> {
     let clean = version.trim_start_matches('v');
@@ -131,6 +158,92 @@ fn extract_version_from_tag(tag: &str) -> Option<String> {
     Some(format!("{}.{}.{}", major, minor, patch))
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::models::GitHubAsset;
+
+    // ── format_app_version ──────────────────────────────────────────────
+
+    #[test]
+    fn a_production_build_reports_the_bare_version() {
+        assert_eq!(format_app_version("0.4.12", None), "0.4.12");
+        // An empty env var (set but blank) must not print a trailing dash.
+        assert_eq!(format_app_version("0.4.12", Some("")), "0.4.12");
+    }
+
+    #[test]
+    fn a_preview_build_reports_its_suffix() {
+        assert_eq!(
+            format_app_version("0.4.12", Some("preview.a1b2c3d")),
+            "0.4.12-preview.a1b2c3d"
+        );
+    }
+
+    // ── pick_update ──────────────────────────────────────────────────────
+
+    fn release(tag: &str, prerelease: bool, asset_names: &[&str]) -> GitHubRelease {
+        GitHubRelease {
+            tag_name: tag.to_string(),
+            html_url: format!("https://example.invalid/{}", tag),
+            body: String::new(),
+            assets: asset_names
+                .iter()
+                .map(|name| GitHubAsset {
+                    name: name.to_string(),
+                    browser_download_url: String::new(),
+                    size: 0,
+                })
+                .collect(),
+            published_at: "2026-01-01T00:00:00Z".to_string(),
+            prerelease,
+        }
+    }
+
+    const LINUX_EXTENSIONS: &[&str] = &[".AppImage", ".deb", ".rpm"];
+
+    #[test]
+    fn a_prerelease_is_never_offered_even_if_its_tag_would_otherwise_win() {
+        let releases = vec![release("v9.9.9", true, &["app-9.9.9.AppImage"])];
+        assert!(pick_update(&releases, (0, 4, 10), LINUX_EXTENSIONS).is_none());
+    }
+
+    #[test]
+    fn a_release_with_no_asset_for_this_platform_is_skipped() {
+        let releases = vec![release("v0.4.12", false, &["app-0.4.12.msi"])];
+        assert!(pick_update(&releases, (0, 4, 10), LINUX_EXTENSIONS).is_none());
+    }
+
+    #[test]
+    fn a_release_that_is_not_newer_is_not_offered() {
+        let releases = vec![release("v0.4.10", false, &["app.AppImage"])];
+        assert!(pick_update(&releases, (0, 4, 10), LINUX_EXTENSIONS).is_none());
+    }
+
+    #[test]
+    fn an_untagged_or_unparseable_release_is_skipped_not_fatal() {
+        // A `-preview.<sha>` tag is exactly the shape this must not choke on
+        // or mistake for an update — it simply never parses as a bare semver.
+        let releases = vec![
+            release("preview-a1b2c3d", false, &["app.AppImage"]),
+            release("v0.4.12", false, &["app.AppImage"]),
+        ];
+        let best = pick_update(&releases, (0, 4, 10), LINUX_EXTENSIONS).unwrap();
+        assert_eq!(best.tag_name, "v0.4.12");
+    }
+
+    #[test]
+    fn the_highest_qualifying_version_wins_not_the_first_or_last_in_the_list() {
+        let releases = vec![
+            release("v0.4.11", false, &["app.AppImage"]),
+            release("v0.4.13", false, &["app.AppImage"]),
+            release("v0.4.12", false, &["app.AppImage"]),
+        ];
+        let best = pick_update(&releases, (0, 4, 10), LINUX_EXTENSIONS).unwrap();
+        assert_eq!(best.tag_name, "v0.4.13");
+    }
+}
+
 /// Check whether a newer container image is available in the registry.
 ///
 /// Compares the local image digest with the remote registry digest using the

app/src-tauri/src/models/update_info.rs

@@ -26,6 +26,15 @@ pub struct GitHubRelease {
     pub body: String,
     pub assets: Vec<GitHubAsset>,
     pub published_at: String,
+    /// Whether GitHub itself has this release marked as a prerelease.
+    /// `#[serde(default)]` rather than required: every response GitHub sends
+    /// carries this, but nothing here should refuse to parse the rest of a
+    /// release over one missing field. No production release is ever
+    /// mirrored with this `true` today — see `check_for_updates`, which
+    /// filters on it explicitly rather than relying on that being an
+    /// accident of what happens to get mirrored.
+    #[serde(default)]
+    pub prerelease: bool,
 }
 
 /// GitHub API asset response (internal).