feat(memory): lucid memory integration with optional backends (#285)

src/memory/backend.rs

@@ -0,0 +1,145 @@
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+pub enum MemoryBackendKind {
+    Sqlite,
+    Lucid,
+    Markdown,
+    None,
+    Unknown,
+}
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+pub struct MemoryBackendProfile {
+    pub key: &'static str,
+    pub label: &'static str,
+    pub auto_save_default: bool,
+    pub uses_sqlite_hygiene: bool,
+    pub sqlite_based: bool,
+    pub optional_dependency: bool,
+}
+
+const SQLITE_PROFILE: MemoryBackendProfile = MemoryBackendProfile {
+    key: "sqlite",
+    label: "SQLite with Vector Search (recommended) — fast, hybrid search, embeddings",
+    auto_save_default: true,
+    uses_sqlite_hygiene: true,
+    sqlite_based: true,
+    optional_dependency: false,
+};
+
+const LUCID_PROFILE: MemoryBackendProfile = MemoryBackendProfile {
+    key: "lucid",
+    label: "Lucid Memory bridge — sync with local lucid-memory CLI, keep SQLite fallback",
+    auto_save_default: true,
+    uses_sqlite_hygiene: true,
+    sqlite_based: true,
+    optional_dependency: true,
+};
+
+const MARKDOWN_PROFILE: MemoryBackendProfile = MemoryBackendProfile {
+    key: "markdown",
+    label: "Markdown Files — simple, human-readable, no dependencies",
+    auto_save_default: true,
+    uses_sqlite_hygiene: false,
+    sqlite_based: false,
+    optional_dependency: false,
+};
+
+const NONE_PROFILE: MemoryBackendProfile = MemoryBackendProfile {
+    key: "none",
+    label: "None — disable persistent memory",
+    auto_save_default: false,
+    uses_sqlite_hygiene: false,
+    sqlite_based: false,
+    optional_dependency: false,
+};
+
+const CUSTOM_PROFILE: MemoryBackendProfile = MemoryBackendProfile {
+    key: "custom",
+    label: "Custom backend — extension point",
+    auto_save_default: true,
+    uses_sqlite_hygiene: false,
+    sqlite_based: false,
+    optional_dependency: false,
+};
+
+const SELECTABLE_MEMORY_BACKENDS: [MemoryBackendProfile; 4] = [
+    SQLITE_PROFILE,
+    LUCID_PROFILE,
+    MARKDOWN_PROFILE,
+    NONE_PROFILE,
+];
+
+pub fn selectable_memory_backends() -> &'static [MemoryBackendProfile] {
+    &SELECTABLE_MEMORY_BACKENDS
+}
+
+pub fn default_memory_backend_key() -> &'static str {
+    SQLITE_PROFILE.key
+}
+
+pub fn classify_memory_backend(backend: &str) -> MemoryBackendKind {
+    match backend {
+        "sqlite" => MemoryBackendKind::Sqlite,
+        "lucid" => MemoryBackendKind::Lucid,
+        "markdown" => MemoryBackendKind::Markdown,
+        "none" => MemoryBackendKind::None,
+        _ => MemoryBackendKind::Unknown,
+    }
+}
+
+pub fn memory_backend_profile(backend: &str) -> MemoryBackendProfile {
+    match classify_memory_backend(backend) {
+        MemoryBackendKind::Sqlite => SQLITE_PROFILE,
+        MemoryBackendKind::Lucid => LUCID_PROFILE,
+        MemoryBackendKind::Markdown => MARKDOWN_PROFILE,
+        MemoryBackendKind::None => NONE_PROFILE,
+        MemoryBackendKind::Unknown => CUSTOM_PROFILE,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn classify_known_backends() {
+        assert_eq!(classify_memory_backend("sqlite"), MemoryBackendKind::Sqlite);
+        assert_eq!(classify_memory_backend("lucid"), MemoryBackendKind::Lucid);
+        assert_eq!(
+            classify_memory_backend("markdown"),
+            MemoryBackendKind::Markdown
+        );
+        assert_eq!(classify_memory_backend("none"), MemoryBackendKind::None);
+    }
+
+    #[test]
+    fn classify_unknown_backend() {
+        assert_eq!(classify_memory_backend("redis"), MemoryBackendKind::Unknown);
+    }
+
+    #[test]
+    fn selectable_backends_are_ordered_for_onboarding() {
+        let backends = selectable_memory_backends();
+        assert_eq!(backends.len(), 4);
+        assert_eq!(backends[0].key, "sqlite");
+        assert_eq!(backends[1].key, "lucid");
+        assert_eq!(backends[2].key, "markdown");
+        assert_eq!(backends[3].key, "none");
+    }
+
+    #[test]
+    fn lucid_profile_is_sqlite_based_optional_backend() {
+        let profile = memory_backend_profile("lucid");
+        assert!(profile.sqlite_based);
+        assert!(profile.optional_dependency);
+        assert!(profile.uses_sqlite_hygiene);
+    }
+
+    #[test]
+    fn unknown_profile_preserves_extensibility_defaults() {
+        let profile = memory_backend_profile("custom-memory");
+        assert_eq!(profile.key, "custom");
+        assert!(profile.auto_save_default);
+        assert!(!profile.uses_sqlite_hygiene);
+    }
+}