diff --git a/mlf-cli/src/config.rs b/mlf-cli/src/config.rs
index 8dd7047..8b3f8e5 100644
--- a/mlf-cli/src/config.rs
+++ b/mlf-cli/src/config.rs
@@ -29,7 +29,7 @@ pub struct MlfConfig {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct SourceConfig {
-    #[serde(default = "default_source_directory")]
+    #[serde(default = "default_source_directory", skip_serializing_if = "is_default_source_directory")]
     pub directory: String,
 }
 
@@ -45,6 +45,10 @@ fn default_source_directory() -> String {
     "./lexicons".to_string()
 }
 
+fn is_default_source_directory(s: &str) -> bool {
+    s == default_source_directory()
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 pub struct OutputConfig {
     pub r#type: String,
@@ -56,10 +60,10 @@ pub struct DependenciesConfig {
     #[serde(default)]
     pub dependencies: Vec<String>,
 
-    #[serde(default = "default_allow_transitive_deps")]
+    #[serde(default = "default_allow_transitive_deps", skip_serializing_if = "is_default_allow_transitive_deps")]
     pub allow_transitive_deps: bool,
 
-    #[serde(default = "default_optimize_transitive_fetches")]
+    #[serde(default = "default_optimize_transitive_fetches", skip_serializing_if = "is_default_optimize_transitive_fetches")]
     pub optimize_transitive_fetches: bool,
 }
 
@@ -71,6 +75,14 @@ fn default_optimize_transitive_fetches() -> bool {
     false
 }
 
+fn is_default_allow_transitive_deps(b: &bool) -> bool {
+    *b == default_allow_transitive_deps()
+}
+
+fn is_default_optimize_transitive_fetches(b: &bool) -> bool {
+    *b == default_optimize_transitive_fetches()
+}
+
 impl Default for DependenciesConfig {
     fn default() -> Self {
         Self {
diff --git a/mlf-cli/src/fetch.rs b/mlf-cli/src/fetch.rs
index 2ee0a36..ce0ffb7 100644
--- a/mlf-cli/src/fetch.rs
+++ b/mlf-cli/src/fetch.rs
@@ -68,8 +68,29 @@ pub fn run_fetch(nsid: Option<String>, save: bool, update: bool, locked: bool) -
 
     match nsid {
         Some(namespace) => {
-            // Fetch single namespace
-            fetch_lexicon(&namespace, &project_root)?;
+            // Fetch single namespace with transitive dependencies
+            let lockfile_path = project_root.join("mlf-lock.toml");
+            let mut lockfile = LockFile::load(&lockfile_path).unwrap_or_else(|_| LockFile::new());
+
+            // Load config to check if transitive deps are enabled
+            let config_path = project_root.join("mlf.toml");
+            let config = MlfConfig::load(&config_path).map_err(FetchError::NoProjectRoot)?;
+
+            fetch_lexicon_with_lock(&namespace, &project_root, &mut lockfile)?;
+
+            // Handle transitive dependencies if enabled
+            if config.dependencies.allow_transitive_deps {
+                println!("\n→ Checking for transitive dependencies...");
+                fetch_transitive_dependencies(
+                    &project_root,
+                    &mut lockfile,
+                    config.dependencies.optimize_transitive_fetches
+                )?;
+            }
+
+            // Save lockfile
+            lockfile.save(&lockfile_path).map_err(FetchError::NoProjectRoot)?;
+            println!("\n→ Updated mlf-lock.toml");
 
             // Save to mlf.toml if --save flag is provided
             if save {
@@ -182,145 +203,153 @@ fn fetch_all_dependencies(project_root: &std::path::Path, update: bool, locked:
         }
     }
 
-    // If transitive dependencies are enabled, iteratively fetch missing deps
+    // If transitive dependencies are enabled, fetch them
     if allow_transitive {
-        let mut iteration = 0;
-        let max_iterations = 10; // Prevent infinite loops
+        fetch_transitive_dependencies(&project_root, &mut lockfile, config.dependencies.optimize_transitive_fetches)?;
+    }
 
-        loop {
-            iteration += 1;
-            if iteration > max_iterations {
-                eprintln!("\nWarning: Reached maximum iteration limit for transitive dependencies");
-                break;
-            }
+    // Save the lockfile
+    lockfile.save(&lockfile_path).map_err(FetchError::NoProjectRoot)?;
+    println!("\n→ Updated mlf-lock.toml");
 
-            // Collect unresolved references
-            let unresolved = match collect_unresolved_references(project_root) {
-                Ok(refs) => refs,
-                Err(e) => {
-                    eprintln!("\nWarning: Failed to analyze dependencies: {}", e);
-                    break;
-                }
-            };
+    if !errors.is_empty() {
+        eprintln!(
+            "\n{} dependency(ies) fetched successfully, {} error(s):",
+            success_count,
+            errors.len()
+        );
+        for (dep, error) in &errors {
+            eprintln!("  {} - {}", dep, error);
+        }
+        return Err(FetchError::HttpError(format!(
+            "Failed to fetch {} dependencies",
+            errors.len()
+        )));
+    }
 
-            // Filter out NSIDs we've already fetched or tried to fetch
-            let new_deps: HashSet<String> = unresolved
-                .into_iter()
-                .filter(|nsid| !fetched_nsids.contains(nsid))
-                .collect();
+    println!("\n✓ Successfully fetched all {} dependencies", success_count);
+    Ok(())
+}
 
-            if new_deps.is_empty() {
+/// Fetch transitive dependencies by iteratively resolving unresolved references
+fn fetch_transitive_dependencies(
+    project_root: &std::path::Path,
+    lockfile: &mut LockFile,
+    optimize_fetches: bool
+) -> Result<(), FetchError> {
+    let mut fetched_nsids = HashSet::new();
+    // Track NSIDs from lockfile as already fetched
+    for nsid in lockfile.lexicons.keys() {
+        fetched_nsids.insert(nsid.clone());
+    }
+
+    let mut iteration = 0;
+    const MAX_ITERATIONS: usize = 10;
+
+    loop {
+        iteration += 1;
+        if iteration > MAX_ITERATIONS {
+            eprintln!("\nWarning: Reached maximum iteration limit for transitive dependencies");
+            break;
+        }
+
+        // Collect unresolved references
+        let unresolved = match collect_unresolved_references(project_root) {
+            Ok(refs) => refs,
+            Err(e) => {
+                eprintln!("\nWarning: Failed to analyze dependencies: {}", e);
                 break;
             }
+        };
 
-            // Determine whether to optimize transitive fetches
-            let should_optimize = config.dependencies.optimize_transitive_fetches;
+        // Filter out NSIDs we've already fetched or tried to fetch
+        let new_deps: HashSet<String> = unresolved
+            .into_iter()
+            .filter(|nsid| !fetched_nsids.contains(nsid))
+            .collect();
 
-            if should_optimize {
-                // Optimize the fetch patterns to reduce number of fetches
-                let optimized_patterns = optimize_fetch_patterns(&new_deps);
+        if new_deps.is_empty() {
+            break;
+        }
 
-                println!("\n→ Found {} unresolved reference(s), fetching {} optimized pattern(s)...",
-                         new_deps.len(), optimized_patterns.len());
+        if optimize_fetches {
+            // Optimize the fetch patterns to reduce number of fetches
+            let optimized_patterns = optimize_fetch_patterns(&new_deps);
 
-                // Track which patterns are wildcards and their constituent NSIDs
-                let mut wildcard_failures: Vec<(String, Vec<String>)> = Vec::new();
+            println!("\n→ Found {} unresolved reference(s), fetching {} optimized pattern(s)...",
+                     new_deps.len(), optimized_patterns.len());
 
-                for pattern in optimized_patterns {
-                    let is_wildcard = pattern.ends_with(".*");
-                    println!("\nFetching transitive dependency: {}", pattern);
-                    fetched_nsids.insert(pattern.clone());
+            // Track which patterns are wildcards and their constituent NSIDs
+            let mut wildcard_failures: Vec<(String, Vec<String>)> = Vec::new();
 
-                    match fetch_lexicon_with_lock(&pattern, project_root, &mut lockfile) {
-                        Ok(()) => {
-                            success_count += 1;
-                        }
-                        Err(e) => {
-                            eprintln!("  Warning: Failed to fetch {}: {}", pattern, e);
-
-                            // If this was a wildcard that failed, collect the individual NSIDs for retry
-                            if is_wildcard {
-                                let pattern_prefix = pattern.strip_suffix(".*").unwrap();
-                                let matching_nsids: Vec<String> = new_deps.iter()
-                                    .filter(|nsid| nsid.starts_with(pattern_prefix))
-                                    .cloned()
-                                    .collect();
-
-                                if !matching_nsids.is_empty() {
-                                    wildcard_failures.push((pattern.clone(), matching_nsids));
-                                }
+            for pattern in optimized_patterns {
+                let is_wildcard = pattern.ends_with(".*");
+                println!("\nFetching transitive dependency: {}", pattern);
+                fetched_nsids.insert(pattern.clone());
+
+                match fetch_lexicon_with_lock(&pattern, project_root, lockfile) {
+                    Ok(()) => {}
+                    Err(e) => {
+                        eprintln!("  Warning: Failed to fetch {}: {}", pattern, e);
+
+                        // If this was a wildcard that failed, collect the individual NSIDs for retry
+                        if is_wildcard {
+                            let pattern_prefix = pattern.strip_suffix(".*").unwrap();
+                            let matching_nsids: Vec<String> = new_deps.iter()
+                                .filter(|nsid| nsid.starts_with(pattern_prefix))
+                                .cloned()
+                                .collect();
+
+                            if !matching_nsids.is_empty() {
+                                wildcard_failures.push((pattern.clone(), matching_nsids));
                             }
                         }
                     }
                 }
+            }
+
+            // Retry failed wildcards with individual NSIDs
+            if !wildcard_failures.is_empty() {
+                println!("\n→ Retrying failed wildcard patterns with individual NSIDs...");
 
-                // Retry failed wildcards with individual NSIDs
-                if !wildcard_failures.is_empty() {
-                    println!("\n→ Retrying failed wildcard patterns with individual NSIDs...");
-
-                    for (failed_pattern, nsids) in wildcard_failures {
-                        println!("  Retrying {} NSIDs from failed pattern: {}", nsids.len(), failed_pattern);
-
-                        for nsid in nsids {
-                            if !fetched_nsids.contains(&nsid) {
-                                println!("    Fetching: {}", nsid);
-                                fetched_nsids.insert(nsid.clone());
-
-                                match fetch_lexicon_with_lock(&nsid, project_root, &mut lockfile) {
-                                    Ok(()) => {
-                                        success_count += 1;
-                                    }
-                                    Err(e) => {
-                                        eprintln!("      Warning: Failed to fetch {}: {}", nsid, e);
-                                    }
+                for (failed_pattern, nsids) in wildcard_failures {
+                    println!("  Retrying {} NSIDs from failed pattern: {}", nsids.len(), failed_pattern);
+
+                    for nsid in nsids {
+                        if !fetched_nsids.contains(&nsid) {
+                            println!("    Fetching: {}", nsid);
+                            fetched_nsids.insert(nsid.clone());
+
+                            match fetch_lexicon_with_lock(&nsid, project_root, lockfile) {
+                                Ok(()) => {}
+                                Err(e) => {
+                                    eprintln!("      Warning: Failed to fetch {}: {}", nsid, e);
                                 }
                             }
                         }
                     }
                 }
-            } else {
-                // Fetch individually without optimization (safer, more predictable)
-                println!("\n→ Found {} unresolved reference(s), fetching individually...",
-                         new_deps.len());
-
-                for nsid in &new_deps {
-                    println!("\nFetching transitive dependency: {}", nsid);
-                    fetched_nsids.insert(nsid.clone());
-
-                    match fetch_lexicon_with_lock(nsid, project_root, &mut lockfile) {
-                        Ok(()) => {
-                            success_count += 1;
-                        }
-                        Err(e) => {
-                            // Don't fail the entire fetch for transitive deps
-                            eprintln!("  Warning: Failed to fetch {}: {}", nsid, e);
-                        }
+            }
+        } else {
+            // Fetch individually without optimization (safer, more predictable)
+            println!("\n→ Found {} unresolved reference(s), fetching individually...",
+                     new_deps.len());
+
+            for nsid in &new_deps {
+                println!("\nFetching transitive dependency: {}", nsid);
+                fetched_nsids.insert(nsid.clone());
+
+                match fetch_lexicon_with_lock(nsid, project_root, lockfile) {
+                    Ok(()) => {}
+                    Err(e) => {
+                        // Don't fail the entire fetch for transitive deps
+                        eprintln!("  Warning: Failed to fetch {}: {}", nsid, e);
                     }
                 }
             }
         }
     }
 
-    // Save the lockfile
-    lockfile.save(&lockfile_path).map_err(FetchError::NoProjectRoot)?;
-    println!("\n→ Updated mlf-lock.toml");
-
-    if !errors.is_empty() {
-        eprintln!(
-            "\n{} dependency(ies) fetched successfully, {} error(s):",
-            success_count,
-            errors.len()
-        );
-        for (dep, error) in &errors {
-            eprintln!("  {} - {}", dep, error);
-        }
-        return Err(FetchError::HttpError(format!(
-            "Failed to fetch {} dependencies",
-            errors.len()
-        )));
-    }
-
-    println!("\n✓ Successfully fetched all {} dependencies", success_count);
     Ok(())
 }
 
@@ -874,8 +903,12 @@ fn collect_unresolved_references(project_root: &std::path::Path) -> Result<HashS
         return Ok(HashSet::new());
     }
 
-    // Build a workspace from all fetched MLF files
-    let mut workspace = Workspace::new();
+    // Build a workspace with std library to avoid fetching std types
+    let mut workspace = Workspace::with_std()
+        .map_err(|e| FetchError::IoError(std::io::Error::new(
+            std::io::ErrorKind::Other,
+            format!("Failed to load standard library: {:?}", e)
+        )))?;
     let mut unresolved = HashSet::new();
 
     // Recursively find all .mlf files
diff --git a/mlf-cli/src/generate/mlf.rs b/mlf-cli/src/generate/mlf.rs
index 17f4715..83310fe 100644
--- a/mlf-cli/src/generate/mlf.rs
+++ b/mlf-cli/src/generate/mlf.rs
@@ -417,7 +417,7 @@ fn generate_query(name: &str, def: &Value, last_segment: &str, ctx: &ConversionC
                 .collect();
 
             if !param_strs.is_empty() {
-                output.push_str(&param_strs.join(","));
+                output.push_str(&param_strs.join(",\n    "));
             }
         }
     }
@@ -514,7 +514,7 @@ fn generate_procedure(name: &str, def: &Value, last_segment: &str, ctx: &Convers
                     .collect();
 
                 if !param_strs.is_empty() {
-                    output.push_str(&param_strs.join(","));
+                    output.push_str(&param_strs.join(",\n    "));
                 }
             }
         }
@@ -652,6 +652,7 @@ fn generate_def_type(name: &str, def: &Value, last_segment: &str, ctx: &Conversi
     }
 
     // Use last segment of NSID for "main" definitions
+    // Keywords are now allowed by the parser, so just escape with backticks
     let def_name = if name == "main" {
         escape_name(last_segment)
     } else {
diff --git a/mlf-lang/src/parser.rs b/mlf-lang/src/parser.rs
index 24b4cec..a713283 100644
--- a/mlf-lang/src/parser.rs
+++ b/mlf-lang/src/parser.rs
@@ -421,7 +421,7 @@ impl Parser {
     fn parse_def_type(&mut self, docs: Vec<DocComment>, annotations: Vec<Annotation>) -> Result<Item, ParseError> {
         let start = self.expect(LexToken::Def)?;
         self.expect(LexToken::Type)?;
-        let name = self.parse_ident()?;
+        let name = self.parse_ident()?;  // Backticked keywords are already converted to Ident by lexer
         self.expect(LexToken::Equals)?;
         let ty = self.parse_type()?;
         let end = self.expect(LexToken::Semicolon)?;
diff --git a/mlf-lang/src/workspace.rs b/mlf-lang/src/workspace.rs
index 9881ec6..96851b7 100644
--- a/mlf-lang/src/workspace.rs
+++ b/mlf-lang/src/workspace.rs
@@ -25,6 +25,9 @@ struct SymbolTable {
 struct ImportTable {
     mappings: BTreeMap<String, ImportedSymbol>,
     used_imports: BTreeSet<String>,
+    // Maps namespace alias to full namespace path
+    // e.g., "example" -> "com.example"
+    namespace_aliases: BTreeMap<String, String>,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -168,7 +171,7 @@ impl Workspace {
             return Err(errors);
         }
 
-        // Check for unused imports
+        // Check for unused imports (warnings only, don't fail)
         if let Err(mut unused_import_errors) = self.check_unused_imports() {
             errors.append(&mut unused_import_errors);
         }
@@ -177,10 +180,15 @@ impl Workspace {
             errors.append(&mut typecheck_errors);
         }
 
-        if errors.is_empty() {
+        // Filter out warnings (UnusedImport) from blocking errors
+        let blocking_errors: Vec<ValidationError> = errors.errors.into_iter()
+            .filter(|e| !matches!(e, ValidationError::UnusedImport { .. }))
+            .collect();
+
+        if blocking_errors.is_empty() {
             Ok(())
         } else {
-            Err(errors)
+            Err(ValidationErrors { errors: blocking_errors })
         }
     }
 
@@ -875,7 +883,11 @@ impl Workspace {
             }
         };
 
-        if !self.modules.contains_key(&target_namespace) {
+        // Check if the target namespace exists or if there are modules with that prefix
+        let namespace_exists = self.modules.contains_key(&target_namespace);
+        let has_children = self.modules.keys().any(|ns| ns.starts_with(&alloc::format!("{}.", target_namespace)));
+
+        if !namespace_exists && !has_children {
             errors.push(ValidationError::UndefinedReference {
                 name: target_namespace.clone(),
                 span: use_stmt.path.span,
@@ -884,23 +896,62 @@ impl Workspace {
             return Err(errors);
         }
 
+        let namespace_alias_to_add: Option<(String, String)> = match &use_stmt.imports {
+            UseImports::All => {
+                // Check for implicit main resolution
+                // If namespace suffix matches a type name, import only that type
+                // Otherwise, this is a namespace alias for path shortening
+                let namespace_suffix = target_namespace.split('.').last().unwrap_or(&target_namespace);
+
+                if let Some(target_module) = self.modules.get(&target_namespace) {
+                    // Module exists - check if there's a type matching the namespace suffix
+                    if target_module.symbols.types.contains_key(namespace_suffix) {
+                        // Implicit main resolution: no namespace alias, just type import
+                        None
+                    } else {
+                        // No type matching namespace suffix - this is a namespace alias
+                        // Create alias: namespace_suffix -> target_namespace
+                        // e.g., "use com.example;" creates alias "example" -> "com.example"
+                        Some((namespace_suffix.to_string(), target_namespace.clone()))
+                    }
+                } else {
+                    // Module doesn't exist but has children - create namespace alias
+                    // e.g., "use com.example;" with only "com.example.defs" module
+                    Some((namespace_suffix.to_string(), target_namespace.clone()))
+                }
+            }
+            UseImports::Items(_) => {
+                // Items imports don't create namespace aliases
+                None
+            }
+        };
+
         let imports_to_add: Vec<(String, ImportedSymbol)> = match &use_stmt.imports {
             UseImports::All => {
-                // Import all types from the namespace
-                let target_module = self.modules.get(&target_namespace).unwrap();
-                target_module.symbols.types.keys()
-                    .map(|type_name| {
+                // Check for implicit main resolution
+                // If namespace suffix matches a type name, import only that type
+                let namespace_suffix = target_namespace.split('.').last().unwrap_or(&target_namespace);
+
+                if let Some(target_module) = self.modules.get(&target_namespace) {
+                    // Check if there's a type matching the namespace suffix
+                    if target_module.symbols.types.contains_key(namespace_suffix) {
+                        // Implicit main resolution: import only the type matching the namespace suffix
                         let imported = ImportedSymbol {
                             original_path: use_stmt.path.segments.iter()
                                 .map(|s| s.name.clone())
-                                .chain(core::iter::once(type_name.clone()))
                                 .collect(),
-                            local_name: type_name.clone(),
+                            local_name: namespace_suffix.to_string(),
                             span: use_stmt.path.span,
                         };
-                        (type_name.clone(), imported)
-                    })
-                    .collect()
+                        vec![(namespace_suffix.to_string(), imported)]
+                    } else {
+                        // Namespace alias only, no type imports
+                        vec![]
+                    }
+                } else {
+                    // Module doesn't exist - namespace alias only
+                    vec![]
+                }
             }
             UseImports::Items(items) => {
                 // Import specific items from the namespace
@@ -974,6 +1025,11 @@ impl Workspace {
             module.imports.mappings.insert(local_name, imported);
         }
 
+        // Add namespace alias if one was created
+        if let Some((alias, full_namespace)) = namespace_alias_to_add {
+            module.imports.namespace_aliases.insert(alias, full_namespace);
+        }
+
         if errors.is_empty() {
             Ok(())
         } else {
@@ -1479,13 +1535,44 @@ impl Workspace {
             return Err(errors);
         }
 
-        let target_namespace = path.segments[..path.segments.len() - 1]
-            .iter()
-            .map(|s| s.name.as_str())
-            .collect::<Vec<_>>()
-            .join(".");
+        // Multi-segment path: check for namespace alias
+        // If the first segment is a namespace alias, expand it
+        let first_segment = &path.segments[0].name;
         let type_name = &path.segments[path.segments.len() - 1].name;
 
+        let target_namespace = if let Some(module) = self.modules.get(current_namespace) {
+            if let Some(full_ns) = module.imports.namespace_aliases.get(first_segment) {
+                // Found a namespace alias! Expand it
+                // e.g., "example.defs.foo" with alias "example" -> "com.example"
+                // The namespace part is "example.defs" which expands to "com.example.defs"
+                // (excluding the last segment "foo" which is the type name)
+                let middle_segments: Vec<&str> = path.segments[1..path.segments.len() - 1]
+                    .iter()
+                    .map(|s| s.name.as_str())
+                    .collect();
+                if middle_segments.is_empty() {
+                    // e.g., "example.foo" -> "com.example"
+                    full_ns.clone()
+                } else {
+                    // e.g., "example.defs.foo" -> "com.example.defs"
+                    alloc::format!("{}.{}", full_ns, middle_segments.join("."))
+                }
+            } else {
+                // No alias, use the path as-is (excluding type name)
+                path.segments[..path.segments.len() - 1]
+                    .iter()
+                    .map(|s| s.name.as_str())
+                    .collect::<Vec<_>>()
+                    .join(".")
+            }
+        } else {
+            path.segments[..path.segments.len() - 1]
+                .iter()
+                .map(|s| s.name.as_str())
+                .collect::<Vec<_>>()
+                .join(".")
+        };
+
         // First try: normal resolution (namespace + type)
         if let Some(module) = self.modules.get(&target_namespace) {
             if module.symbols.types.contains_key(type_name) {
@@ -1496,9 +1583,14 @@ impl Workspace {
         // Second try: implicit main resolution
         // If com.atproto.repo.strongRef fails, try treating the full path as a namespace
         // and look for a type named "strongRef" (matching the namespace suffix)
-        let full_namespace = &full_path;
-        if let Some(module) = self.modules.get(full_namespace) {
-            let namespace_suffix = full_namespace.split('.').last().unwrap_or(full_namespace);
+        // Need to use the expanded path if an alias was used
+        let expanded_full_path = if target_namespace.is_empty() {
+            type_name.to_string()
+        } else {
+            alloc::format!("{}.{}", target_namespace, type_name)
+        };
+        if let Some(module) = self.modules.get(&expanded_full_path) {
+            let namespace_suffix = expanded_full_path.split('.').last().unwrap_or(&expanded_full_path);
             if namespace_suffix == type_name && module.symbols.types.contains_key(type_name) {
                 return Ok(());
             }
@@ -1582,19 +1674,6 @@ mod tests {
         assert!(ws.modules.contains_key("prelude"));
     }
 
-    #[test]
-    fn test_use_import_all() {
-        let mut ws = Workspace::new();
-
-        let a = parse_lexicon("record foo {} inline type bar = string;").unwrap();
-        ws.add_module("a".into(), a).unwrap();
-
-        let b = parse_lexicon("use a; record baz { x: foo, y: bar, }").unwrap();
-        ws.add_module("b".into(), b).unwrap();
-
-        assert!(ws.resolve().is_ok());
-    }
-
     #[test]
     fn test_use_import_with_alias() {
         let mut ws = Workspace::new();
@@ -2106,10 +2185,9 @@ mod tests {
         let b = parse_lexicon("use a.foo as Foo; record bar {}").unwrap();
         ws.add_module("b".into(), b).unwrap();
 
+        // UnusedImport is now a warning, not a blocking error
         let result = ws.resolve();
-        assert!(result.is_err());
-        let errors = result.unwrap_err();
-        assert!(errors.errors.iter().any(|e| matches!(e, ValidationError::UnusedImport { .. })));
+        assert!(result.is_ok());
     }
 
     #[test]
@@ -2136,11 +2214,155 @@ mod tests {
         let b = parse_lexicon("use a; record baz {}").unwrap();
         ws.add_module("b".into(), b).unwrap();
 
+        // UnusedImport is now a warning, not a blocking error
         let result = ws.resolve();
-        assert!(result.is_err());
-        let errors = result.unwrap_err();
-        // Should have 2 unused import errors (foo and bar)
-        let unused_count = errors.errors.iter().filter(|e| matches!(e, ValidationError::UnusedImport { .. })).count();
-        assert_eq!(unused_count, 2);
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_use_implicit_main_resolution() {
+        let mut ws = Workspace::new();
+
+        // Create a namespace where the namespace suffix matches a type name
+        // No @main annotation needed for implicit main resolution
+        let profile_ns = parse_lexicon(r#"
+            def type color = {
+                red!: integer,
+                green!: integer,
+                blue!: integer,
+            };
+
+            record profile {
+                color: color,
+            }
+        "#).unwrap();
+        ws.add_module("place.stream.chat.profile".into(), profile_ns).unwrap();
+
+        // Import using implicit main resolution - should only import profile, not color
+        let bookmark = parse_lexicon(r#"
+            use place.stream.chat.profile;
+
+            record bookmark {
+                owner!: profile,
+            }
+        "#).unwrap();
+        ws.add_module("com.example.bookmark".into(), bookmark).unwrap();
+
+        // Should resolve without unused import warning for color
+        let result = ws.resolve();
+        assert!(result.is_ok());
+
+        // Verify that only profile was imported (implicit main resolution)
+        let imports = ws.get_imports("com.example.bookmark");
+        assert_eq!(imports.len(), 1);
+        assert_eq!(imports[0].0, "profile");
+    }
+
+    #[test]
+    fn test_use_namespace_alias() {
+        let mut ws = Workspace::new();
+
+        // Create a namespace where the suffix doesn't match a type name
+        let defs = parse_lexicon(r#"
+            def type foo = string;
+            def type bar = integer;
+        "#).unwrap();
+        ws.add_module("com.example.defs".into(), defs).unwrap();
+
+        // Using "use com.example;" creates a namespace alias "example" -> "com.example"
+        // This allows referencing types via the shortened path
+        let app = parse_lexicon(r#"
+            use com.example;
+
+            record thing {
+                x!: example.defs.foo,
+                y!: example.defs.bar,
+            }
+        "#).unwrap();
+        ws.add_module("com.example.app".into(), app).unwrap();
+
+        // Should resolve successfully using the namespace alias
+        let result = ws.resolve();
+        if let Err(ref e) = result {
+            eprintln!("Errors: {:?}", e);
+        }
+        assert!(result.is_ok());
+
+        // Verify that no types were imported (it's just a namespace alias)
+        let imports = ws.get_imports("com.example.app");
+        assert_eq!(imports.len(), 0);
+    }
+
+    #[test]
+    fn test_use_namespace_alias_nested() {
+        let mut ws = Workspace::new();
+
+        // Create nested namespaces
+        let actor_defs = parse_lexicon(r#"
+            def type profileView = {
+                did!: string,
+                handle!: string,
+            };
+        "#).unwrap();
+        ws.add_module("app.bsky.actor.defs".into(), actor_defs).unwrap();
+
+        let feed_post = parse_lexicon(r#"
+            def type post = {
+                text!: string,
+            };
+        "#).unwrap();
+        ws.add_module("app.bsky.feed.post".into(), feed_post).unwrap();
+
+        // Use namespace alias to shorten references
+        let like = parse_lexicon(r#"
+            use app.bsky;
+
+            record like {
+                subject!: bsky.feed.post,
+                actor!: bsky.actor.defs.profileView,
+            }
+        "#).unwrap();
+        ws.add_module("app.bsky.feed.like".into(), like).unwrap();
+
+        let result = ws.resolve();
+        if let Err(ref e) = result {
+            eprintln!("Errors: {:?}", e);
+        }
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_use_namespace_reference_full_path() {
+        let mut ws = Workspace::new();
+
+        // Create a namespace where the suffix doesn't match a type name
+        let defs = parse_lexicon(r#"
+            def type foo = string;
+            def type bar = integer;
+        "#).unwrap();
+        ws.add_module("com.example.defs".into(), defs).unwrap();
+
+        // Using "use com.example.defs;" where "defs" is not a type name
+        // creates a namespace alias "defs" -> "com.example.defs"
+        let app = parse_lexicon(r#"
+            use com.example.defs;
+
+            record thing {
+                x!: defs.foo,
+                y!: defs.bar,
+            }
+        "#).unwrap();
+        ws.add_module("com.example.app".into(), app).unwrap();
+
+        // Should resolve successfully using the namespace alias
+        let result = ws.resolve();
+        if let Err(ref e) = result {
+            eprintln!("Errors: {:?}", e);
+        }
+        assert!(result.is_ok());
+
+        // Verify that no types were imported (it's just a namespace alias)
+        let imports = ws.get_imports("com.example.app");
+        assert_eq!(imports.len(), 0);
     }
 }