fix: Prefer GNU linux builds in install scripts for duckdb support, and gate duckdb support on linux hosts that are MUSL until MUSL support is added

scripts/install_coyote.ps1

@@ -62,7 +62,13 @@ if ($os -eq 'windows') {
   else { $candidates += 'coyote-aarch64-apple-darwin.tar.gz' }
 } elseif ($os -eq 'linux') {
   if ($arch -eq 'x86_64') {
-    $candidates += 'coyote-x86_64-unknown-linux-gnu.tar.gz'
+    # Mirror install_coyote.sh: only offer the gnu build when glibc is detected.
+    $libc = 'musl'
+    try { getconf GNU_LIBC_VERSION *> $null; if ($LASTEXITCODE -eq 0) { $libc = 'gnu' } } catch { }
+    try { if ((ldd --version 2>&1 | Out-String) -imatch 'glibc') { $libc = 'gnu' } } catch { }
+    if ($libc -eq 'gnu') {
+      $candidates += 'coyote-x86_64-unknown-linux-gnu.tar.gz'
+    }
     $candidates += 'coyote-x86_64-unknown-linux-musl.tar.gz'
   } else {
     $candidates += 'coyote-aarch64-unknown-linux-musl.tar.gz'

src/config/update.rs

@@ -68,9 +68,32 @@ fn normalize_version(requested: Option<String>) -> Option<String> {
     }
 }
 
+fn host_has_glibc() -> bool {
+    if process::Command::new("getconf")
+        .arg("GNU_LIBC_VERSION")
+        .output()
+        .is_ok_and(|out| out.status.success())
+    {
+        return true;
+    }
+    process::Command::new("ldd")
+        .arg("--version")
+        .output()
+        .is_ok_and(|out| {
+            let combined = format!(
+                "{}{}",
+                String::from_utf8_lossy(&out.stdout),
+                String::from_utf8_lossy(&out.stderr)
+            );
+            combined.to_lowercase().contains("glibc")
+        })
+}
+
 fn preferred_update_target() -> Option<&'static str> {
     match (env::consts::OS, env::consts::ARCH) {
+        ("linux", "x86_64") if host_has_glibc() => Some("x86_64-unknown-linux-gnu"),
         ("linux", "x86_64") => Some("x86_64-unknown-linux-musl"),
+        // No aarch64 gnu asset is published; musl is the only option.
         ("linux", "aarch64") => Some("aarch64-unknown-linux-musl"),
         _ => None,
     }

src/rag/mod.rs

@@ -1869,6 +1869,12 @@ fn select_embedding_model(models: &[&Model]) -> Result<String> {
 }
 
 pub(crate) fn select_rag_driver() -> Result<String> {
+    // Statically linked musl builds cannot dlopen DuckDB extensions, so duckdb is not offered there.
+    #[cfg(target_env = "musl")]
+    let options = vec![
+        "yaml   — portable, in-memory HNSW; usable from several Coyote processes at once (default)",
+    ];
+    #[cfg(not(target_env = "musl"))]
     let options = vec![
         "yaml   — portable, in-memory HNSW; usable from several Coyote processes at once (default)",
         "duckdb — persistent on-disk store; vectors and content survive restarts; HNSW approximate search.",

src/rag/providers/duckdb.rs

@@ -85,6 +85,21 @@ pub struct DuckDbProvider {
 }
 
 impl DuckDbProvider {
+    /// Fail fast on musl builds, before any filesystem or DuckDB work. Coyote's musl
+    /// builds are statically linked, and a statically linked binary cannot dlopen the
+    /// `vss`/`fts` extension shared objects, so this driver can never work there.
+    fn reject_musl() -> Result<()> {
+        #[cfg(target_env = "musl")]
+        bail!(
+            "The duckdb RAG driver is unavailable in this build of coyote: musl builds \
+             are statically linked, and a statically linked binary cannot load DuckDB \
+             extensions like `vss`/`fts` (dlopen is unsupported). Use the `qdrant` RAG \
+             driver instead, or a gnu-libc build of coyote."
+        );
+        #[cfg(not(target_env = "musl"))]
+        Ok(())
+    }
+
     /// Open (or create) the DuckDB file. `dim` is the embedding vector dimension,
     /// supplied by the caller who knows the model.
     ///
@@ -95,6 +110,7 @@ impl DuckDbProvider {
     /// created or initialized here, or lazily through `ensure_writable` on the rebuild
     /// path.
     pub fn open(db_path: &Path, dim: usize) -> Result<Self> {
+        Self::reject_musl()?;
         let (conn, writable) = Self::open_for_workload(db_path, dim)?;
         // A reopened file may already carry a live FTS index from a previous session,
         // in which case keyword search works immediately.
@@ -173,6 +189,7 @@ impl DuckDbProvider {
     }
 
     pub fn introspect_dim(db_path: &Path) -> Result<Option<usize>> {
+        Self::reject_musl()?;
         if !db_path.exists() {
             return Ok(None);
         }
@@ -819,7 +836,9 @@ impl RagProvider for DuckDbProvider {
     }
 }
 
-#[cfg(test)]
+// Not compiled for musl: `open` bails there (statically linked binaries cannot dlopen
+// the extension shared objects), so every test in this module would fail at setup.
+#[cfg(all(test, not(target_env = "musl")))]
 mod tests {
     use super::*;
     use crate::rag::provider::RagProvider;