diff --git a/Cargo.lock b/Cargo.lock
index 05e1252..4431c1c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1391,6 +1391,7 @@ dependencies = [
  "reqwest",
  "serde",
  "serde_json",
+ "serde_yaml",
  "shellexpand",
  "thiserror 1.0.69",
  "tokio",
@@ -3078,6 +3079,19 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_yaml"
+version = "0.9.34+deprecated"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a8b1a1a2ebf674015cc02edccce75287f1a0130d394307b36743c2f5d504b47"
+dependencies = [
+ "indexmap",
+ "itoa",
+ "ryu",
+ "serde",
+ "unsafe-libyaml",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"
@@ -3667,6 +3681,12 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1fc81956842c57dac11422a97c3b8195a1ff727f06e85c84ed2e8aa277c9a0fd"
 
+[[package]]
+name = "unsafe-libyaml"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "673aac59facbab8a9007c7f6108d11f63b603f7cabff99fabf650fea5c32b861"
+
 [[package]]
 name = "url"
 version = "2.5.7"
diff --git a/crates/g3-core/Cargo.toml b/crates/g3-core/Cargo.toml
index 0e86851..67f9a2e 100644
--- a/crates/g3-core/Cargo.toml
+++ b/crates/g3-core/Cargo.toml
@@ -25,3 +25,4 @@ chrono = { version = "0.4", features = ["serde"] }
 rand = "0.8"
 regex = "1.0"
 shellexpand = "3.1"
+serde_yaml = "0.9"
diff --git a/crates/g3-core/src/code_search.rs b/crates/g3-core/src/code_search.rs
new file mode 100644
index 0000000..1e4d38f
--- /dev/null
+++ b/crates/g3-core/src/code_search.rs
@@ -0,0 +1,787 @@
+//! Code search functionality using ast-grep for syntax-aware semantic searches
+
+use anyhow::{anyhow, Result};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::collections::HashMap;
+use std::process::Stdio;
+use std::time::{Duration, Instant};
+use tokio::io::{AsyncBufReadExt, BufReader};
+use tokio::process::Command;
+use tokio::sync::Semaphore;
+use tracing::{debug, error, info, warn};
+
+/// Maximum number of searches allowed per request
+const MAX_SEARCHES: usize = 20;
+
+/// Default timeout for individual searches in seconds
+const DEFAULT_TIMEOUT_SECS: u64 = 60;
+
+/// Default maximum concurrency
+const DEFAULT_MAX_CONCURRENCY: usize = 4;
+
+/// Default maximum matches per search
+const DEFAULT_MAX_MATCHES: usize = 500;
+
+/// Search specification for a single ast-grep search
+#[derive(Debug, Clone, Deserialize)]
+pub struct SearchSpec {
+    pub name: String,
+    pub mode: SearchMode,
+    
+    // Pattern mode fields
+    pub pattern: Option<String>,
+    pub language: Option<String>,
+    
+    // YAML mode fields
+    pub rule_yaml: Option<String>,
+    
+    // Common fields
+    pub paths: Option<Vec<String>>,
+    pub globs: Option<Vec<String>>,
+    pub json_style: Option<JsonStyle>,
+    pub context: Option<u32>,
+    pub threads: Option<u32>,
+    pub include_metadata: Option<bool>,
+    pub no_ignore: Option<Vec<NoIgnoreType>>,
+    pub severity: Option<HashMap<String, SeverityLevel>>,
+    pub timeout_secs: Option<u64>,
+}
+
+/// Search mode: pattern or yaml
+#[derive(Debug, Clone, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum SearchMode {
+    Pattern,
+    Yaml,
+}
+
+/// JSON output style
+#[derive(Debug, Clone, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum JsonStyle {
+    Pretty,
+    Stream,
+    Compact,
+}
+
+impl Default for JsonStyle {
+    fn default() -> Self {
+        JsonStyle::Stream
+    }
+}
+
+/// No-ignore types
+#[derive(Debug, Clone, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum NoIgnoreType {
+    Hidden,
+    Dot,
+    Exclude,
+    Global,
+    Parent,
+    Vcs,
+}
+
+/// Severity levels for YAML rules
+#[derive(Debug, Clone, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum SeverityLevel {
+    Error,
+    Warning,
+    Info,
+    Hint,
+    Off,
+}
+
+/// Request structure for code search
+#[derive(Debug, Deserialize)]
+pub struct CodeSearchRequest {
+    pub searches: Vec<SearchSpec>,
+    pub max_concurrency: Option<usize>,
+    pub max_matches_per_search: Option<usize>,
+}
+
+/// Result of a single search
+#[derive(Debug, Serialize)]
+pub struct SearchResult {
+    pub name: String,
+    pub mode: String,
+    pub status: String,
+    pub cmd: Vec<String>,
+    pub match_count: Option<usize>,
+    pub truncated: Option<bool>,
+    pub matches: Option<Vec<Value>>,
+    pub stderr: Option<String>,
+    pub exit_code: Option<i32>,
+    pub duration_ms: u64,
+}
+
+/// Summary of all searches
+#[derive(Debug, Serialize)]
+pub struct SearchSummary {
+    pub completed: usize,
+    pub total: usize,
+    pub total_matches: usize,
+    pub duration_ms: u64,
+}
+
+/// Complete response structure
+#[derive(Debug, Serialize)]
+pub struct CodeSearchResponse {
+    pub summary: SearchSummary,
+    pub searches: Vec<SearchResult>,
+}
+
+/// YAML rule structure for validation
+#[derive(Debug, Deserialize)]
+struct YamlRule {
+    pub id: String,
+    pub language: String,
+    pub rule: Value,
+}
+
+/// Execute a batch of code searches using ast-grep
+pub async fn execute_code_search(request: CodeSearchRequest) -> Result<CodeSearchResponse> {
+    let start_time = Instant::now();
+    
+    // Validate request
+    if request.searches.is_empty() {
+        return Err(anyhow!("No searches specified"));
+    }
+    
+    if request.searches.len() > MAX_SEARCHES {
+        return Err(anyhow!(
+            "Too many searches: {} (max: {})",
+            request.searches.len(),
+            MAX_SEARCHES
+        ));
+    }
+    
+    // Check if ast-grep is available
+    check_ast_grep_available().await?;
+    
+    let max_concurrency = request.max_concurrency.unwrap_or(DEFAULT_MAX_CONCURRENCY);
+    let max_matches = request.max_matches_per_search.unwrap_or(DEFAULT_MAX_MATCHES);
+    
+    // Create semaphore for concurrency control
+    let semaphore = std::sync::Arc::new(Semaphore::new(max_concurrency));
+    
+    // Execute searches concurrently
+    let mut tasks = Vec::new();
+    
+    for search in request.searches {
+        let sem = semaphore.clone();
+        let task = tokio::spawn(async move {
+            let _permit = sem.acquire().await.unwrap();
+            execute_single_search(search, max_matches).await
+        });
+        tasks.push(task);
+    }
+    
+    // Wait for all searches to complete
+    let mut results = Vec::new();
+    let mut total_matches = 0;
+    let mut completed = 0;
+    
+    for task in tasks {
+        match task.await {
+            Ok(result) => {
+                if result.status == "ok" {
+                    completed += 1;
+                    if let Some(count) = result.match_count {
+                        total_matches += count;
+                    }
+                }
+                results.push(result);
+            }
+            Err(e) => {
+                error!("Task join error: {}", e);
+                // Create an error result
+                results.push(SearchResult {
+                    name: "unknown".to_string(),
+                    mode: "unknown".to_string(),
+                    status: "error".to_string(),
+                    cmd: vec![],
+                    match_count: None,
+                    truncated: None,
+                    matches: None,
+                    stderr: Some(format!("Task execution error: {}", e)),
+                    exit_code: None,
+                    duration_ms: 0,
+                });
+            }
+        }
+    }
+    
+    let total_duration = start_time.elapsed();
+    
+    Ok(CodeSearchResponse {
+        summary: SearchSummary {
+            completed,
+            total: results.len(),
+            total_matches,
+            duration_ms: total_duration.as_millis() as u64,
+        },
+        searches: results,
+    })
+}
+
+/// Execute a single search
+async fn execute_single_search(search: SearchSpec, max_matches: usize) -> SearchResult {
+    let start_time = Instant::now();
+    let timeout_secs = search.timeout_secs.unwrap_or(DEFAULT_TIMEOUT_SECS);
+    
+    // Validate the search specification
+    if let Err(e) = validate_search_spec(&search) {
+        return SearchResult {
+            name: search.name,
+            mode: format!("{:?}", search.mode).to_lowercase(),
+            status: "error".to_string(),
+            cmd: vec![],
+            match_count: None,
+            truncated: None,
+            matches: None,
+            stderr: Some(format!("Validation error: {}", e)),
+            exit_code: None,
+            duration_ms: start_time.elapsed().as_millis() as u64,
+        };
+    }
+    
+    // Build command
+    let cmd_args = match build_ast_grep_command(&search) {
+        Ok(args) => args,
+        Err(e) => {
+            return SearchResult {
+                name: search.name,
+                mode: format!("{:?}", search.mode).to_lowercase(),
+                status: "error".to_string(),
+                cmd: vec![],
+                match_count: None,
+                truncated: None,
+                matches: None,
+                stderr: Some(format!("Command build error: {}", e)),
+                exit_code: None,
+                duration_ms: start_time.elapsed().as_millis() as u64,
+            };
+        }
+    };
+    
+    debug!("Executing ast-grep command: {:?}", cmd_args);
+    
+    // Execute with timeout
+    let timeout_duration = Duration::from_secs(timeout_secs);
+    
+    match tokio::time::timeout(timeout_duration, run_ast_grep_command(&cmd_args)).await {
+        Ok(Ok((stdout, stderr, exit_code))) => {
+            let duration_ms = start_time.elapsed().as_millis() as u64;
+            
+            if exit_code == 0 {
+                // Parse JSON output
+                match parse_ast_grep_output(&stdout, max_matches) {
+                    Ok((matches, truncated)) => {
+                        SearchResult {
+                            name: search.name,
+                            mode: format!("{:?}", search.mode).to_lowercase(),
+                            status: "ok".to_string(),
+                            cmd: cmd_args,
+                            match_count: Some(matches.len()),
+                            truncated: Some(truncated),
+                            matches: Some(matches),
+                            stderr: if stderr.is_empty() { None } else { Some(stderr) },
+                            exit_code: None,
+                            duration_ms,
+                        }
+                    }
+                    Err(e) => {
+                        SearchResult {
+                            name: search.name,
+                            mode: format!("{:?}", search.mode).to_lowercase(),
+                            status: "error".to_string(),
+                            cmd: cmd_args,
+                            match_count: None,
+                            truncated: None,
+                            matches: None,
+                            stderr: Some(format!("JSON parse error: {}\nRaw output: {}", e, stdout)),
+                            exit_code: Some(exit_code),
+                            duration_ms,
+                        }
+                    }
+                }
+            } else {
+                SearchResult {
+                    name: search.name,
+                    mode: format!("{:?}", search.mode).to_lowercase(),
+                    status: "error".to_string(),
+                    cmd: cmd_args,
+                    match_count: None,
+                    truncated: None,
+                    matches: None,
+                    stderr: Some(stderr),
+                    exit_code: Some(exit_code),
+                    duration_ms,
+                }
+            }
+        }
+        Ok(Err(e)) => {
+            SearchResult {
+                name: search.name,
+                mode: format!("{:?}", search.mode).to_lowercase(),
+                status: "error".to_string(),
+                cmd: cmd_args,
+                match_count: None,
+                truncated: None,
+                matches: None,
+                stderr: Some(format!("Execution error: {}", e)),
+                exit_code: None,
+                duration_ms: start_time.elapsed().as_millis() as u64,
+            }
+        }
+        Err(_) => {
+            SearchResult {
+                name: search.name,
+                mode: format!("{:?}", search.mode).to_lowercase(),
+                status: "timeout".to_string(),
+                cmd: cmd_args,
+                match_count: None,
+                truncated: None,
+                matches: None,
+                stderr: Some(format!("Search timed out after {} seconds", timeout_secs)),
+                exit_code: None,
+                duration_ms: start_time.elapsed().as_millis() as u64,
+            }
+        }
+    }
+}
+
+/// Validate a search specification
+fn validate_search_spec(search: &SearchSpec) -> Result<()> {
+    match search.mode {
+        SearchMode::Pattern => {
+            if search.pattern.is_none() || search.pattern.as_ref().unwrap().is_empty() {
+                return Err(anyhow!("Pattern mode requires non-empty 'pattern' field"));
+            }
+        }
+        SearchMode::Yaml => {
+            let rule_yaml = search.rule_yaml.as_ref()
+                .ok_or_else(|| anyhow!("YAML mode requires 'rule_yaml' field"))?;
+            
+            if rule_yaml.is_empty() {
+                return Err(anyhow!("YAML mode requires non-empty 'rule_yaml' field"));
+            }
+            
+            // Parse and validate YAML structure
+            let parsed: YamlRule = serde_yaml::from_str(rule_yaml)
+                .map_err(|e| anyhow!("Invalid YAML rule: {}", e))?;
+            
+            if parsed.id.is_empty() {
+                return Err(anyhow!("YAML rule must have non-empty 'id' field"));
+            }
+            
+            if parsed.language.is_empty() {
+                return Err(anyhow!("YAML rule must have non-empty 'language' field"));
+            }
+            
+            // Validate language is supported (basic check)
+            validate_language(&parsed.language)?;
+        }
+    }
+    
+    // Validate context range
+    if let Some(context) = search.context {
+        if context > 20 {
+            return Err(anyhow!("Context lines cannot exceed 20"));
+        }
+    }
+    
+    Ok(())
+}
+
+/// Validate that a language is supported by ast-grep
+fn validate_language(language: &str) -> Result<()> {
+    let supported_languages = [
+        "rust", "javascript", "typescript", "python", "java", "c", "cpp", "csharp",
+        "go", "html", "css", "json", "yaml", "xml", "bash", "kotlin", "swift",
+        "php", "ruby", "scala", "dart", "lua", "r", "sql", "dockerfile",
+        "Rust", "JavaScript", "TypeScript", "Python", "Java", "C", "Cpp", "CSharp",
+        "Go", "Html", "Css", "Json", "Yaml", "Xml", "Bash", "Kotlin", "Swift",
+        "Php", "Ruby", "Scala", "Dart", "Lua", "R", "Sql", "Dockerfile"
+    ];
+    
+    if !supported_languages.contains(&language) {
+        warn!("Language '{}' may not be supported by ast-grep", language);
+    }
+    
+    Ok(())
+}
+
+/// Build ast-grep command arguments
+fn build_ast_grep_command(search: &SearchSpec) -> Result<Vec<String>> {
+    let mut args = vec!["ast-grep".to_string()];
+    
+    match search.mode {
+        SearchMode::Pattern => {
+            args.push("run".to_string());
+            
+            // Add pattern
+            args.push("-p".to_string());
+            args.push(search.pattern.as_ref().unwrap().clone());
+            
+            // Add language if specified
+            if let Some(ref lang) = search.language {
+                args.push("-l".to_string());
+                args.push(lang.clone());
+            }
+        }
+        SearchMode::Yaml => {
+            args.push("scan".to_string());
+            
+            // Add inline rules
+            args.push("--inline-rules".to_string());
+            args.push(search.rule_yaml.as_ref().unwrap().clone());
+            
+            // Add include-metadata if requested
+            if search.include_metadata.unwrap_or(false) {
+                args.push("--include-metadata".to_string());
+            }
+            
+            // Add severity overrides
+            if let Some(ref severity_map) = search.severity {
+                for (rule_id, severity) in severity_map {
+                    match severity {
+                        SeverityLevel::Error => {
+                            args.push("--error".to_string());
+                            args.push(rule_id.clone());
+                        }
+                        SeverityLevel::Warning => {
+                            args.push("--warning".to_string());
+                            args.push(rule_id.clone());
+                        }
+                        SeverityLevel::Info => {
+                            args.push("--info".to_string());
+                            args.push(rule_id.clone());
+                        }
+                        SeverityLevel::Hint => {
+                            args.push("--hint".to_string());
+                            args.push(rule_id.clone());
+                        }
+                        SeverityLevel::Off => {
+                            args.push("--off".to_string());
+                            args.push(rule_id.clone());
+                        }
+                    }
+                }
+            }
+        }
+    }
+    
+    // Add common arguments
+    
+    // Add globs if specified
+    if let Some(ref globs) = search.globs {
+        if !globs.is_empty() {
+            args.push("--globs".to_string());
+            args.push(globs.join(","));
+        }
+    }
+    
+    // Add context
+    if let Some(context) = search.context {
+        args.push("-C".to_string());
+        args.push(context.to_string());
+    }
+    
+    // Add threads
+    if let Some(threads) = search.threads {
+        args.push("-j".to_string());
+        args.push(threads.to_string());
+    }
+    
+    // Add JSON output style
+    let json_style = search.json_style.as_ref().unwrap_or(&JsonStyle::Stream);
+    let json_arg = match json_style {
+        JsonStyle::Pretty => "--json=pretty",
+        JsonStyle::Stream => "--json=stream",
+        JsonStyle::Compact => "--json=compact",
+    };
+    args.push(json_arg.to_string());
+    
+    // Add no-ignore options
+    if let Some(ref no_ignore_list) = search.no_ignore {
+        for no_ignore_type in no_ignore_list {
+            let flag = match no_ignore_type {
+                NoIgnoreType::Hidden => "--no-ignore=hidden",
+                NoIgnoreType::Dot => "--no-ignore=dot",
+                NoIgnoreType::Exclude => "--no-ignore=exclude",
+                NoIgnoreType::Global => "--no-ignore=global",
+                NoIgnoreType::Parent => "--no-ignore=parent",
+                NoIgnoreType::Vcs => "--no-ignore=vcs",
+            };
+            args.push(flag.to_string());
+        }
+    }
+    
+    // Add paths (default to current directory if none specified)
+    if let Some(ref paths) = search.paths {
+        if !paths.is_empty() {
+            args.extend(paths.clone());
+        } else {
+            args.push(".".to_string());
+        }
+    } else {
+        args.push(".".to_string());
+    }
+    
+    Ok(args)
+}
+
+/// Run ast-grep command and capture output
+async fn run_ast_grep_command(args: &[String]) -> Result<(String, String, i32)> {
+    let mut cmd = Command::new(&args[0]);
+    cmd.args(&args[1..]);
+    cmd.stdout(Stdio::piped());
+    cmd.stderr(Stdio::piped());
+    
+    debug!("Running command: {:?}", args);
+    
+    let mut child = cmd.spawn()
+        .map_err(|e| anyhow!("Failed to spawn ast-grep process: {}", e))?;
+    
+    let stdout = child.stdout.take().unwrap();
+    let stderr = child.stderr.take().unwrap();
+    
+    let stdout_reader = BufReader::new(stdout);
+    let stderr_reader = BufReader::new(stderr);
+    
+    let stdout_task = tokio::spawn(async move {
+        let mut lines = stdout_reader.lines();
+        let mut output = String::new();
+        while let Ok(Some(line)) = lines.next_line().await {
+            if !output.is_empty() {
+                output.push('\n');
+            }
+            output.push_str(&line);
+        }
+        output
+    });
+    
+    let stderr_task = tokio::spawn(async move {
+        let mut lines = stderr_reader.lines();
+        let mut output = String::new();
+        while let Ok(Some(line)) = lines.next_line().await {
+            if !output.is_empty() {
+                output.push('\n');
+            }
+            output.push_str(&line);
+        }
+        output
+    });
+    
+    let status = child.wait().await
+        .map_err(|e| anyhow!("Failed to wait for ast-grep process: {}", e))?;
+    
+    let stdout_output = stdout_task.await
+        .map_err(|e| anyhow!("Failed to read stdout: {}", e))?;
+    let stderr_output = stderr_task.await
+        .map_err(|e| anyhow!("Failed to read stderr: {}", e))?;
+    
+    let exit_code = status.code().unwrap_or(-1);
+    
+    Ok((stdout_output, stderr_output, exit_code))
+}
+
+/// Parse ast-grep JSON output
+fn parse_ast_grep_output(output: &str, max_matches: usize) -> Result<(Vec<Value>, bool)> {
+    if output.trim().is_empty() {
+        return Ok((vec![], false));
+    }
+    
+    let mut matches = Vec::new();
+    let mut truncated = false;
+    
+    // Handle stream format (line-delimited JSON)
+    for line in output.lines() {
+        let line = line.trim();
+        if line.is_empty() {
+            continue;
+        }
+        
+        match serde_json::from_str::<Value>(line) {
+            Ok(match_obj) => {
+                if matches.len() >= max_matches {
+                    truncated = true;
+                    break;
+                }
+                matches.push(match_obj);
+            }
+            Err(e) => {
+                debug!("Failed to parse JSON line '{}': {}", line, e);
+                // Try to parse the entire output as a single JSON array
+                match serde_json::from_str::<Vec<Value>>(output) {
+                    Ok(array_matches) => {
+                        let take_count = array_matches.len().min(max_matches);
+                        let total_count = array_matches.len();
+                        matches = array_matches.into_iter().take(take_count).collect();
+                        truncated = take_count < total_count;
+                        break;
+                    }
+                    Err(e2) => {
+                        return Err(anyhow!(
+                            "Failed to parse ast-grep output as line-delimited JSON or JSON array. Line error: {}, Array error: {}",
+                            e, e2
+                        ));
+                    }
+                }
+            }
+        }
+    }
+    
+    Ok((matches, truncated))
+}
+
+/// Check if ast-grep is available and provide installation hints if not
+async fn check_ast_grep_available() -> Result<()> {
+    match Command::new("ast-grep")
+        .arg("--version")
+        .output()
+        .await
+    {
+        Ok(output) => {
+            if output.status.success() {
+                let version = String::from_utf8_lossy(&output.stdout);
+                info!("Found ast-grep: {}", version.trim());
+                Ok(())
+            } else {
+                Err(anyhow!("ast-grep command failed: {}", String::from_utf8_lossy(&output.stderr)))
+            }
+        }
+        Err(_) => {
+            Err(anyhow!(
+                "ast-grep not found. Please install it using one of these methods:\n\n\
+                • Homebrew (macOS): brew install ast-grep\n\
+                • MacPorts (macOS): sudo port install ast-grep\n\
+                • Nix: nix-env -iA nixpkgs.ast-grep\n\
+                • Cargo: cargo install ast-grep\n\
+                • npm: npm install -g @ast-grep/cli\n\
+                • pip: pip install ast-grep\n\n\
+                For more installation options, visit: https://ast-grep.github.io/guide/quick-start.html"
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    
+    #[test]
+    fn test_validate_pattern_search() {
+        let search = SearchSpec {
+            name: "test".to_string(),
+            mode: SearchMode::Pattern,
+            pattern: Some("fn $NAME() {}".to_string()),
+            language: Some("rust".to_string()),
+            rule_yaml: None,
+            paths: None,
+            globs: None,
+            json_style: None,
+            context: None,
+            threads: None,
+            include_metadata: None,
+            no_ignore: None,
+            severity: None,
+            timeout_secs: None,
+        };
+        
+        assert!(validate_search_spec(&search).is_ok());
+    }
+    
+    #[test]
+    fn test_validate_yaml_search() {
+        let yaml_rule = r#"
+id: test-rule
+language: Rust
+rule:
+  pattern: "fn $NAME() {}"
+"#;
+        
+        let search = SearchSpec {
+            name: "test".to_string(),
+            mode: SearchMode::Yaml,
+            pattern: None,
+            language: None,
+            rule_yaml: Some(yaml_rule.to_string()),
+            paths: None,
+            globs: None,
+            json_style: None,
+            context: None,
+            threads: None,
+            include_metadata: None,
+            no_ignore: None,
+            severity: None,
+            timeout_secs: None,
+        };
+        
+        assert!(validate_search_spec(&search).is_ok());
+    }
+    
+    #[test]
+    fn test_build_pattern_command() {
+        let search = SearchSpec {
+            name: "test".to_string(),
+            mode: SearchMode::Pattern,
+            pattern: Some("fn $NAME() {}".to_string()),
+            language: Some("rust".to_string()),
+            rule_yaml: None,
+            paths: Some(vec!["src/".to_string()]),
+            globs: None,
+            json_style: Some(JsonStyle::Stream),
+            context: Some(2),
+            threads: Some(4),
+            include_metadata: None,
+            no_ignore: None,
+            severity: None,
+            timeout_secs: None,
+        };
+        
+        let cmd = build_ast_grep_command(&search).unwrap();
+        
+        assert_eq!(cmd[0], "ast-grep");
+        assert_eq!(cmd[1], "run");
+        assert!(cmd.contains(&"-p".to_string()));
+        assert!(cmd.contains(&"fn $NAME() {}".to_string()));
+        assert!(cmd.contains(&"-l".to_string()));
+        assert!(cmd.contains(&"rust".to_string()));
+        assert!(cmd.contains(&"--json=stream".to_string()));
+        assert!(cmd.contains(&"-C".to_string()));
+        assert!(cmd.contains(&"2".to_string()));
+        assert!(cmd.contains(&"-j".to_string()));
+        assert!(cmd.contains(&"4".to_string()));
+        assert!(cmd.contains(&"src/".to_string()));
+    }
+    
+    #[test]
+    fn test_parse_stream_json() {
+        let output = r#"{"file":"test.rs","text":"fn hello() {}"}
+{"file":"test2.rs","text":"fn world() {}"}"#;
+        
+        let (matches, truncated) = parse_ast_grep_output(output, 10).unwrap();
+        
+        assert_eq!(matches.len(), 2);
+        assert!(!truncated);
+        assert_eq!(matches[0]["file"], "test.rs");
+        assert_eq!(matches[1]["file"], "test2.rs");
+    }
+    
+    #[test]
+    fn test_parse_truncated_output() {
+        let output = r#"{"file":"test1.rs","text":"fn a() {}"}
+{"file":"test2.rs","text":"fn b() {}"}
+{"file":"test3.rs","text":"fn c() {}"}"#;
+        
+        let (matches, truncated) = parse_ast_grep_output(output, 2).unwrap();
+        
+        assert_eq!(matches.len(), 2);
+        assert!(truncated);
+    }
+}
diff --git a/crates/g3-core/src/lib.rs b/crates/g3-core/src/lib.rs
index 1b8b12e..e8f7569 100644
--- a/crates/g3-core/src/lib.rs
+++ b/crates/g3-core/src/lib.rs
@@ -2,6 +2,7 @@ pub mod error_handling;
 pub mod project;
 pub mod task_result;
 pub mod ui_writer;
+pub mod code_search;
 pub use task_result::TaskResult;
 
 #[cfg(test)]
@@ -1184,10 +1185,26 @@ The tool will execute immediately and you'll receive the result (success or erro
 # Instructions
 
 1. Analyze the request and break down into smaller tasks if appropriate
-2. Execute ONE tool at a time
+2. Execute ONE tool at a time. An exception exists for when you're writing files. See below.
 3. STOP when the original request was satisfied
 4. Call the final_output tool when done
 
+Exception to using ONE tool at a time:
+If all you’re doing is WRITING files, and you don’t need to do anything else between each step.
+You can issue MULTIPLE write_file tool calls in a request, however you may ONLY make a SINGLE write_file call for any file in that request.
+For example you may call:
+[START OF REQUEST]
+write_file(\"helper.rs\", \"...\")
+write_file(\"file2.txt\", \"...\")
+[DONE]
+
+But NOT:
+[START OF REQUEST]
+write_file(\"helper.rs\", \"...\")
+write_file(\"file2.txt\", \"...\")
+write_file(\"helper.rs\", \"...\")
+[DONE]
+
 # Task Management
 
 Use todo_read and todo_write for tasks with 3+ steps, multiple files/components, or uncertain scope.
@@ -1860,6 +1877,64 @@ Template:
                 }),
             },
         ];
+        
+        // Add code_search tool
+        tools.push(Tool {
+            name: "code_search".to_string(),
+            description: "Batch syntax-aware searches via ast-grep. Supports up to 20 pattern or YAML-rule searches in parallel; returns JSON matches (stream-collated).".to_string(),
+            input_schema: json!({
+                "type": "object",
+                "properties": {
+                    "searches": {
+                        "type": "array",
+                        "maxItems": 20,
+                        "items": {
+                            "type": "object",
+                            "properties": {
+                                "name": { "type": "string", "description": "Label for this search." },
+                                "mode": {
+                                    "type": "string",
+                                    "enum": ["pattern", "yaml"],
+                                    "description": "`pattern` uses `ast-grep run`; `yaml` uses `ast-grep scan --inline-rules`."
+                                },
+                                // pattern mode (fast one-off)
+                                "pattern": { "type": "string", "description": "ast-grep pattern code (e.g., \"async fn $NAME($$$ARGS) { $$$ }\")"},
+                                "language": { "type": "string", "description": "Optional language for pattern mode; ast-grep may infer from file extensions if omitted." },
+                                // yaml mode (full rule object)
+                                "rule_yaml": { "type": "string", "description": "A full YAML rule object text. Must include `id`, `language`, and `rule`." },
+                                // targeting
+                                "paths": { "type": "array", "items": { "type": "string" }, "description": "Paths/dirs to search. Defaults to current dir if empty." },
+                                "globs": { "type": "array", "items": { "type": "string" }, "description": "Optional include/exclude globs for CLI --globs." },
+                                // result formatting & performance knobs
+                                "json_style": { "type": "string", "enum": ["pretty","stream","compact"], "default": "stream", "description": "Use stream for large codebases." },
+                                "context": { "type": "integer", "minimum": 0, "maximum": 20, "default": 0, "description": "CLI -C context lines in text output; also affects JSON `lines` field." },
+                                "threads": { "type": "integer", "minimum": 1, "description": "Optional override for ast-grep -j (per process)." },
+                                "include_metadata": { "type": "boolean", "default": false, "description": "If yaml mode and rule has metadata, add --include-metadata." },
+                                // robustness
+                                "no_ignore": {
+                                    "type": "array",
+                                    "items": { "type": "string", "enum": ["hidden","dot","exclude","global","parent","vcs"] },
+                                    "description": "Forwarded to --no-ignore to bypass ignore files/hidden."
+                                },
+                                // severity overrides for yaml mode
+                                "severity": {
+                                    "type": "object",
+                                    "additionalProperties": { "type": "string", "enum": ["error","warning","info","hint","off"] },
+                                    "description": "Optional map<ruleId, severity> -> passed via --error/--warning/--info/--hint/--off."
+                                },
+                                // per-search timeout seconds (default 60)
+                                "timeout_secs": { "type": "integer", "minimum": 1, "default": 60 }
+                            },
+                            "required": ["name","mode"]
+                        }
+                    },
+                    // global concurrency & truncation
+                    "max_concurrency": { "type": "integer", "minimum": 1, "default": 4 },
+                    "max_matches_per_search": { "type": "integer", "minimum": 1, "default": 500 }
+                },
+                "required": ["searches"]
+            }),
+        });
 
         // Add WebDriver tools if enabled
         if enable_webdriver {
@@ -4437,6 +4512,41 @@ Template:
                     Ok("❌ Computer control not enabled. Set computer_control.enabled = true in config.".to_string())
                 }
             }
+            "code_search" => {
+                debug!("Processing code_search tool call");
+                
+                // Parse the request
+                let request: crate::code_search::CodeSearchRequest = match serde_json::from_value(tool_call.args.clone()) {
+                    Ok(req) => req,
+                    Err(e) => {
+                        return Ok(format!("❌ Invalid code_search arguments: {}", e));
+                    }
+                };
+                
+                // Execute the code search
+                match crate::code_search::execute_code_search(request).await {
+                    Ok(response) => {
+                        // Serialize the response to JSON
+                        match serde_json::to_string_pretty(&response) {
+                            Ok(json_output) => {
+                                Ok(format!("✅ Code search completed\n{}", json_output))
+                            }
+                            Err(e) => {
+                                Ok(format!("❌ Failed to serialize response: {}", e))
+                            }
+                        }
+                    }
+                    Err(e) => {
+                        // Check if it's an ast-grep not found error and provide helpful message
+                        let error_msg = e.to_string();
+                        if error_msg.contains("ast-grep not found") {
+                            Ok(format!("❌ {}", error_msg))
+                        } else {
+                            Ok(format!("❌ Code search failed: {}", error_msg))
+                        }
+                    }
+                }
+            }
             _ => {
                 warn!("Unknown tool: {}", tool_call.tool);
                 Ok(format!("❓ Unknown tool: {}", tool_call.tool))