fix(plugins): harden marketplace loading

Use public GitHub metadata to avoid unauthenticated API limits. Read bundled manifests before enabling installs and surface startup load failures.

src/app/mod.rs

@@ -523,6 +523,9 @@ pub(super) struct OpenCADStudio {
     /// `external_plugins` — compatible, with a library, dlopen'd at startup).
     #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
     loaded_plugin_ids: rustc_hash::FxHashSet<String>,
+    /// Startup load failures keyed by plugin id. The Plugin Manager uses these
+    /// to distinguish an installed-but-failed package from one awaiting restart.
+    plugin_load_errors: rustc_hash::FxHashMap<String, String>,
     /// Curated plugin registry fetched from the OpenCADStudio repo.
     plugin_registry: Vec<crate::plugin::external::RegistryEntry>,
     /// True while the curated registry request is in flight.
@@ -540,7 +543,8 @@ pub(super) struct OpenCADStudio {
     /// Live filter for installed and available plugin cards.
     plugin_search_input: String,
     /// Installable release tags fetched per linked repo (for the dropdown).
-    repo_release_tags: rustc_hash::FxHashMap<String, Vec<String>>,
+    repo_release_tags:
+        rustc_hash::FxHashMap<String, Vec<crate::plugin::external::ReleaseInfo>>,
     /// The release tag currently selected per linked repo.
     repo_selected_tag: rustc_hash::FxHashMap<String, String>,
     /// Repository currently shown in the Plugin Manager detail pane.
@@ -2174,8 +2178,11 @@ pub enum Message {
     RecentThumbsLoaded(
         Vec<(std::path::PathBuf, Option<iced::widget::image::Handle>)>,
     ),
-    /// Installable release tags fetched for `owner/repo`.
+    /// Installable releases and manifest API versions fetched for `owner/repo`.
-    PluginReleasesFetched(String, Result<Vec<String>, String>),
+    PluginReleasesFetched(
+        String,
+        Result<Vec<crate::plugin::external::ReleaseInfo>, String>,
+    ),
     /// Choose a release tag for a repo (`repo`, `tag`).
     PluginReleaseSelect(String, String),
     /// Select a plugin source and show its GitHub README in the detail pane.
@@ -2696,6 +2703,7 @@ impl OpenCADStudio {
             disabled_plugins: rustc_hash::FxHashSet::default(),
             external_plugins: Vec::new(),
             loaded_plugin_ids: rustc_hash::FxHashSet::default(),
+            plugin_load_errors: rustc_hash::FxHashMap::default(),
             plugin_registry: Vec::new(),
             plugin_registry_loading: false,
             plugin_registry_error: None,
@@ -2934,6 +2942,7 @@ impl OpenCADStudio {
                 if let Err(e) = res {
                     app.command_line
                         .push_error(&format!("Plugin '{id}' failed to load: {e}"));
+                    app.plugin_load_errors.insert(id, e);
                 }
             }
             app.loaded_plugin_ids = crate::plugin::external::loaded_ids().into_iter().collect();

src/app/update/file.rs

@@ -273,19 +273,13 @@ impl OpenCADStudio {
         )
     }
 
-    /// Background task: fetch `owner/repo`'s installable release tags.
+    /// Background task: fetch `owner/repo`'s installable releases and their
+    /// manifest API versions.
     #[cfg(not(target_arch = "wasm32"))]
     pub(in crate::app) fn fetch_releases_task(&self, repo: String) -> Task<Message> {
         let label = repo.clone();
         Task::perform(
-            async move {
+            async move { crate::plugin::marketplace::fetch_release_info(&repo) },
-                crate::plugin::marketplace::fetch_releases(&repo).map(|rs| {
-                    rs.into_iter()
-                        .filter(|r| r.installable())
-                        .map(|r| r.tag)
-                        .collect::<Vec<_>>()
-                })
-            },
             move |res| Message::PluginReleasesFetched(label, res),
         )
     }

src/app/update/mod.rs

@@ -4699,17 +4699,20 @@ impl OpenCADStudio {
                 }
                 Task::none()
             }
-            Message::PluginReleasesFetched(repo, Ok(tags)) => {
+            Message::PluginReleasesFetched(repo, Ok(releases)) => {
-                if let Some(first) = tags.first() {
+                if let Some(first) = releases.first() {
                     self.repo_selected_tag
                         .entry(repo.clone())
-                        .or_insert_with(|| first.clone());
+                        .or_insert_with(|| first.tag.clone());
                 }
                 if self.marketplace_status == format!("Fetching releases for {repo}…") {
                     self.marketplace_status =
-                        format!("Repository added. {} installable release(s) found.", tags.len());
+                        format!(
+                            "Repository added. {} installable release(s) found.",
+                            releases.len()
+                        );
                 }
-                self.repo_release_tags.insert(repo, tags);
+                self.repo_release_tags.insert(repo, releases);
                 Task::none()
             }
             Message::PluginReleasesFetched(repo, Err(e)) => {
@@ -4754,6 +4757,7 @@ impl OpenCADStudio {
             }
             Message::PluginInstalled(Ok(id)) => {
                 self.marketplace_status = format!("Installed '{id}'. Restart to load it.");
+                self.plugin_load_errors.remove(&id);
                 #[cfg(not(target_arch = "wasm32"))]
                 {
                     self.external_plugins = crate::plugin::external::discover();
@@ -4771,6 +4775,7 @@ impl OpenCADStudio {
                         Ok(()) => {
                             self.marketplace_status =
                                 format!("Uninstalled '{id}'. Restart to unload it.");
+                            self.plugin_load_errors.remove(&id);
                             self.external_plugins = crate::plugin::external::discover();
                         }
                         Err(e) => {

src/app/view/modal.rs

@@ -114,6 +114,7 @@ impl OpenCADStudio {
                                 &self.disabled_plugins,
                                 &self.external_plugins,
                                 &self.loaded_plugin_ids,
+                                &self.plugin_load_errors,
                                 crate::ui::window::plugin_manager::MarketView {
                                     registry: &self.plugin_registry,
                                     registry_loading: self.plugin_registry_loading,

src/plugin/external.rs

@@ -25,6 +25,13 @@ pub struct RegistryEntry {
     pub description: String,
 }
 
+/// Installable release metadata shown by the marketplace before download.
+#[derive(Debug, Clone)]
+pub struct ReleaseInfo {
+    pub tag: String,
+    pub api_version: u32,
+}
+
 /// An add-on package found on disk (not necessarily loaded or compatible).
 #[derive(Debug, Clone)]
 pub struct ExternalPlugin {
@@ -48,7 +55,7 @@ pub struct ExternalPlugin {
 impl ExternalPlugin {
     /// True when the package's API version is supported by this host.
     pub fn api_compatible(&self) -> bool {
-        ocs_plugin_api::host_accepts_plugin_version(self.api_version)
+        self.api_version == ocs_plugin_api::API_VERSION
     }
 
     /// True when the package can be loaded today: compatible API *and* a native
@@ -348,7 +355,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn api_v2_plugin_from_template_is_compatible() {
+    fn api_v2_plugin_from_template_is_incompatible() {
         let toml = r#"
 [plugin]
 id = "opencad.my_plugin"
@@ -367,7 +374,7 @@ xdata_apps = ["MYPLUGIN_RECORD"]
         assert_eq!(p.api_version, 2);
         assert_eq!(p.repository.as_deref(), Some("example/opencad-my-plugin"));
         assert!(p.command_prefixes.contains(&"MP_".to_string()));
-        assert!(p.api_compatible(), "API v2 plugins must run on API v3 host");
+        assert!(!p.api_compatible(), "old API plugins must be rebuilt");
     }
 
     #[test]

src/plugin/marketplace.rs

@@ -13,7 +13,7 @@ use std::io::Read as _;
 use std::path::{Path, PathBuf};
 
 use super::external;
-use super::external::RegistryEntry;
+use super::external::{RegistryEntry, ReleaseInfo};
 
 /// The curated registry, read from the OpenCADStudio repo's `main` branch.
 pub(crate) const REGISTRY_URL: &str =
@@ -109,8 +109,68 @@ fn agent() -> ureq::Agent {
 
 const UA: &str = concat!("OpenCADStudio/", env!("CARGO_PKG_VERSION"));
 
-/// Fetch the releases of `owner/repo` from the GitHub API.
+/// Fetch releases without consuming GitHub API quota. The public Atom feed
+/// supplies tags and the expanded-assets endpoint supplies download links.
+/// Fall back to the API only if GitHub changes either public representation.
 pub fn fetch_releases(repo: &str) -> Result<Vec<Release>, String> {
+    match fetch_releases_public(repo) {
+        Ok(releases) => Ok(releases),
+        Err(public_error) => fetch_releases_api(repo).map_err(|api_error| {
+            format!(
+                "public release metadata failed: {public_error}; \
+                 GitHub API fallback failed: {api_error}"
+            )
+        }),
+    }
+}
+
+fn fetch_releases_public(repo: &str) -> Result<Vec<Release>, String> {
+    let atom_url = format!("https://github.com/{repo}/releases.atom");
+    let atom = download_string(&atom_url)?;
+    let tag_marker = format!("https://github.com/{repo}/releases/tag/");
+    let mut tags = atom
+        .lines()
+        .filter_map(|line| {
+            let start = line.find(&tag_marker)? + tag_marker.len();
+            let rest = &line[start..];
+            let end = rest.find('"')?;
+            let tag = &rest[..end];
+            (!tag.is_empty()).then(|| tag.to_string())
+        })
+        .collect::<Vec<_>>();
+    tags.dedup();
+    if tags.is_empty() {
+        return Err("release feed contains no tags".to_string());
+    }
+
+    let mut releases = Vec::new();
+    for tag in tags {
+        let assets_url = format!("https://github.com/{repo}/releases/expanded_assets/{tag}");
+        let html = download_string(&assets_url)?;
+        let asset_prefix = format!("/{repo}/releases/download/{tag}/");
+        let mut assets = html
+            .split("href=\"")
+            .skip(1)
+            .filter_map(|tail| {
+                let end = tail.find('"')?;
+                let href = &tail[..end];
+                if !href.starts_with(&asset_prefix) {
+                    return None;
+                }
+                let name = href.rsplit('/').next()?.to_string();
+                Some(Asset {
+                    name,
+                    url: format!("https://github.com{href}"),
+                })
+            })
+            .collect::<Vec<_>>();
+        assets.dedup_by(|left, right| left.url == right.url);
+        releases.push(Release { tag, assets });
+    }
+    Ok(releases)
+}
+
+fn fetch_releases_api(repo: &str) -> Result<Vec<Release>, String> {
     let url = format!("https://api.github.com/repos/{repo}/releases");
     let body = agent()
         .get(&url)
@@ -145,8 +205,46 @@ pub fn fetch_releases(repo: &str) -> Result<Vec<Release>, String> {
     Ok(out)
 }
 
+/// Fetch installable releases and read each bundled manifest so compatibility
+/// is known before the Plugin Manager offers an Install action.
+pub fn fetch_release_info(repo: &str) -> Result<Vec<ReleaseInfo>, String> {
+    let releases = fetch_releases(repo)?;
+    let mut info = Vec::new();
+    let mut last_error = None;
+    for release in releases.into_iter().filter(Release::installable) {
+        let result = (|| {
+            let manifest_asset = release
+                .toml_asset()
+                .ok_or_else(|| format!("release {} has no plugin.toml", release.tag))?;
+            let manifest_text = download_string(&manifest_asset.url)?;
+            let manifest = external::parse_plugin_toml(&manifest_text)
+                .ok_or_else(|| format!("release {} plugin.toml is missing an id", release.tag))?;
+            Ok::<_, String>(ReleaseInfo {
+                tag: release.tag,
+                api_version: manifest.api_version,
+            })
+        })();
+        match result {
+            Ok(release) => info.push(release),
+            Err(error) => last_error = Some(error),
+        }
+    }
+    if info.is_empty() {
+        Err(last_error.unwrap_or_else(|| "no installable releases found".to_string()))
+    } else {
+        Ok(info)
+    }
+}
+
 /// Fetch the repository README from its default branch as raw Markdown.
 pub fn fetch_readme(repo: &str) -> Result<String, String> {
+    // GitHub's raw host is not subject to the unauthenticated REST API's
+    // 60-request/hour limit. `HEAD` resolves the repository's default branch.
+    let raw_url = format!("https://raw.githubusercontent.com/{repo}/HEAD/README.md");
+    if let Ok(readme) = download_string(&raw_url) {
+        return Ok(readme);
+    }
+
     let url = format!("https://api.github.com/repos/{repo}/readme");
     agent()
         .get(&url)
@@ -193,11 +291,10 @@ pub fn install(release: &Release, repository: &str) -> Result<String, String> {
 
     let toml_text = download_string(&toml.url)?;
     let manifest = external::parse_plugin_toml(&toml_text).ok_or("plugin.toml is missing an id")?;
-    if !ocs_plugin_api::host_accepts_plugin_version(manifest.api_version) {
+    if manifest.api_version != ocs_plugin_api::API_VERSION {
         return Err(format!(
-            "API version {} is incompatible (host supports {}-{})",
+            "API version {} is incompatible (host requires {})",
             manifest.api_version,
-            ocs_plugin_api::API_VERSION_MIN_SUPPORTED,
             ocs_plugin_api::API_VERSION
         ));
     }

src/ui/window/plugin_manager.rs

@@ -7,7 +7,7 @@
 #![cfg_attr(target_arch = "wasm32", allow(dead_code))]
 
 use crate::app::Message;
-use crate::plugin::external::{ExternalPlugin, RegistryEntry};
+use crate::plugin::external::{ExternalPlugin, RegistryEntry, ReleaseInfo};
 use iced::widget::{
     button, column, container, markdown, row, rule, scrollable, text, text_input, Space,
 };
@@ -27,7 +27,7 @@ pub struct MarketView<'a> {
     pub input: &'a str,
     pub search: &'a str,
     pub repos: &'a [String],
-    pub release_tags: &'a FxHashMap<String, Vec<String>>,
+    pub release_tags: &'a FxHashMap<String, Vec<ReleaseInfo>>,
     pub selected_tag: &'a FxHashMap<String, String>,
     pub selected_repo: Option<&'a str>,
     pub readmes: &'a FxHashMap<String, Result<markdown::Content, String>>,
@@ -212,15 +212,20 @@ fn external_card<'a>(
     repository: Option<String>,
     update_tag: Option<String>,
     loaded: bool,
+    load_error: Option<&str>,
     disabled: bool,
     selected: bool,
 ) -> Element<'a, Message> {
+    let failed_old_api =
+        load_error.is_some() && p.api_version != ocs_plugin_api::API_VERSION;
     let (status, kind) = if loaded && disabled {
         ("Disabled", StatusKind::Muted)
     } else if loaded {
         ("Loaded", StatusKind::Success)
-    } else if !p.api_compatible() {
+    } else if !p.api_compatible() || failed_old_api {
         ("API incompatible", StatusKind::Danger)
+    } else if load_error.is_some() {
+        ("Load failed", StatusKind::Danger)
     } else if !p.lib_present {
         ("No library", StatusKind::Warning)
     } else {
@@ -249,6 +254,26 @@ fn external_card<'a>(
                 .style(muted_style),
         );
     }
+    if let Some(error) = load_error {
+        let detail = if failed_old_api {
+            format!(
+                "Plugin API {} is incompatible with this build's API {} ribbon ABI. \
+                 Update or rebuild the plugin.",
+                p.api_version,
+                ocs_plugin_api::API_VERSION,
+            )
+        } else {
+            format!("Load failed: {error}")
+        };
+        info_body = info_body.push(
+            text(detail)
+                .size(11)
+                .width(Fill)
+                .style(|theme: &Theme| iced::widget::text::Style {
+                    color: Some(theme.palette().danger.base.color),
+                }),
+        );
+    }
 
     let info: Element<'a, Message> = if let Some(repo) = repository.clone() {
         button(info_body.width(Fill))
@@ -316,11 +341,21 @@ fn pill_icon_button<'a>(
 /// Release dropdown + Install (+ optional unlink) for one repo.
 fn install_controls<'a>(
     repo: &str,
-    tags: Vec<String>,
+    releases: Vec<ReleaseInfo>,
     selected: Option<String>,
     removable: bool,
 ) -> Element<'a, Message> {
     let repo_s = repo.to_string();
+    let tags = releases
+        .iter()
+        .map(|release| release.tag.clone())
+        .collect::<Vec<_>>();
+    let selected_api = selected.as_ref().and_then(|selected| {
+        releases
+            .iter()
+            .find(|release| release.tag == *selected)
+            .map(|release| release.api_version)
+    });
     let picker: Element<'_, Message> = if tags.is_empty() {
         text("no releases").size(11).style(muted_style).into()
     } else {
@@ -330,17 +365,20 @@ fn install_controls<'a>(
         .text_size(12)
         .into()
     };
-    let mut controls = row![
+    let action = match selected_api {
-        picker,
+        Some(api_version) if api_version == ocs_plugin_api::API_VERSION => {
-        Space::new().width(8),
+            pill_button(
-        pill_button(
+                "Install",
-            "Install",
+                Message::PluginInstall(repo_s.clone()),
-            Message::PluginInstall(repo_s.clone()),
+                button::success,
-            button::success,
+            )
-        ),
+        }
-    ]
+        Some(_) => status_badge("Incompatible", StatusKind::Danger),
-    .align_y(iced::Center)
+        None => status_badge("Unavailable", StatusKind::Muted),
-    .spacing(4);
+    };
+    let mut controls = row![picker, Space::new().width(8), action]
+        .align_y(iced::Center)
+        .spacing(4);
     if removable {
         controls = controls.push(Space::new().width(6));
         controls = controls.push(pill_icon_button(
@@ -766,6 +804,7 @@ pub fn view_window<'a>(
     disabled: &FxHashSet<String>,
     externals: &[ExternalPlugin],
     loaded: &FxHashSet<String>,
+    load_errors: &FxHashMap<String, String>,
     market: MarketView<'a>,
     theme: &'a Theme,
     sizing: crate::ui::modal::ModalSizing,
@@ -796,12 +835,22 @@ pub fn view_window<'a>(
             let update_tag = repository
                 .as_ref()
                 .and_then(|repo| market.release_tags.get(repo))
-                .and_then(|tags| newest_update(&p.version, tags));
+                .and_then(|releases| {
+                    let compatible_tags = releases
+                        .iter()
+                        .filter(|release| {
+                            release.api_version == ocs_plugin_api::API_VERSION
+                        })
+                        .map(|release| release.tag.clone())
+                        .collect::<Vec<_>>();
+                    newest_update(&p.version, &compatible_tags)
+                });
             list = list.push(external_card(
                 p,
                 repository,
                 update_tag,
                 loaded.contains(&p.id),
+                load_errors.get(&p.id).map(String::as_str),
                 disabled.contains(&p.id),
                 selected,
             ));