feat(cli): impact subcommand to show impact what will be affected if node changes

ast/src/lang/graphs/array_graph.rs

@@ -947,4 +947,21 @@ impl ArrayGraph {
         let edge_type = sanitize_string(&format!("{}", edge.edge));
         format!("{}-{}-{}", source_key, target_key, edge_type,)
     }
+
+    pub fn find_dependents(
+        &self,
+        target_name: &str,
+        target_file: &str,
+        edge_types: &[EdgeType],
+    ) -> Vec<(NodeRef, EdgeType)> {
+        self.edges
+            .iter()
+            .filter(|e| {
+                edge_types.contains(&e.edge)
+                    && e.target.node_data.name == target_name
+                    && e.target.node_data.file == target_file
+            })
+            .map(|e| (e.source.clone(), e.edge.clone()))
+            .collect()
+    }
 }

cli/src/args.rs

@@ -71,6 +71,8 @@ pub enum Commands {
     Changes(ChangesArgs),
     /// Show a dependency tree for a named node
     Deps(DepsArgs),
+    /// Show what is affected if a node changes (reverse dependency tree)
+    Impact(ImpactArgs),
 }
 
 #[derive(Debug, Args)]
@@ -155,6 +157,33 @@ pub struct DepsArgs {
     pub files: Vec<String>,
 }
 
+#[derive(Debug, Args)]
+pub struct ImpactArgs {
+    /// Name of the node to check impact for
+    #[arg(long)]
+    pub name: Option<String>,
+
+    /// File containing the node (seeds all nodes in file when --name is omitted)
+    #[arg(long)]
+    pub file: Option<String>,
+
+    /// Maximum traversal depth (0 = unlimited, default: 3)
+    #[arg(long, default_value = "3")]
+    pub depth: usize,
+
+    /// Only match seed nodes of this type (e.g. Function, Class, Endpoint)
+    #[arg(long)]
+    pub r#type: Option<String>,
+
+    /// Include unverified (cross-file unresolved) calls (default: true)
+    #[arg(long, default_value_t = true, action = ArgAction::Set)]
+    pub allow: bool,
+
+    /// Files or directories to parse
+    #[arg(value_name = "FILE_OR_DIR", num_args = 1..)]
+    pub files: Vec<String>,
+}
+
 impl CliArgs {
     pub fn parse_and_expand() -> Result<Self> {
         let mut args = Self::parse();
@@ -188,6 +217,10 @@ impl CliArgs {
             return Ok(args);
         }
 
+        if let Some(Commands::Impact(_)) = &args.command {
+            return Ok(args);
+        }
+
         Ok(args)
     }
 }