feat: violation row export with --show-violations

src/main.rs

@@ -10,7 +10,7 @@ mod storage;
 
 use output::OutputFormat;
 use rules::RulesFile;
-use runner::run_rule;
+use runner::{fetch_violation_samples, run_rule};
 use storage::register_data;
 
 use crate::{
@@ -35,6 +35,9 @@ struct Cli {
     /// Print full error chain on failure
     #[arg(long)]
     verbose: bool,
+    /// Show first N violating rows per failed rule (default 5)
+    #[arg(long, value_name = "N", default_missing_value = "5", num_args = 0..=1)]
+    show_violations: Option<u64>,
 }
 
 #[tokio::main]
@@ -102,11 +105,19 @@ async fn run(args: Cli) -> anyhow::Result<()> {
     }
     let mut results: Vec<RuleResult> = Vec::new();
     for rule in &rules.rules {
-        let result = run_rule(&ctx, rule, total_rows)
+        let mut result = run_rule(&ctx, rule, total_rows)
             .await
             .with_context(|| format!("Rule '{}' failed to execute", rule.name))?;
         if matches!(result.status, RuleStatus::Fail) {
             any_failed = true;
+            if let Some(limit) = args.show_violations {
+                let samples = fetch_violation_samples(&ctx, rule, limit)
+                    .await
+                    .with_context(|| {
+                        format!("Failed to fetch violation samples for rule '{}'", rule.name)
+                    })?;
+                result.sample_rows = Some(samples);
+            }
         }
         results.push(result);
     }

src/output.rs

@@ -45,16 +45,65 @@ pub fn build_json(results: &[RuleResult]) -> String {
 }
 
 pub fn build_table(results: &[RuleResult]) -> String {
+    let has_samples = results
+        .iter()
+        .any(|r| r.sample_rows.as_ref().is_some_and(|s| !s.is_empty()));
+
     let mut table = Table::new();
-    table.set_header(["RULE", "STATUS", "VIOLATIONS", "TOTAL", "RATE"]);
-    results.iter().for_each(|res| {
-        table.add_row([
-            res.name.clone(),
-            format!("{}", res.status),
-            res.violations.to_string(),
-            res.total_rows.to_string(),
-            format!("{:.1}%", res.violation_rate * 100.0),
+    if has_samples {
+        table.set_header([
+            "RULE",
+            "STATUS",
+            "VIOLATIONS",
+            "TOTAL",
+            "RATE",
+            "SAMPLE VIOLATIONS",
         ]);
+    } else {
+        table.set_header(["RULE", "STATUS", "VIOLATIONS", "TOTAL", "RATE"]);
+    }
+    results.iter().for_each(|res| {
+        if has_samples {
+            let sample_str = match &res.sample_rows {
+                Some(rows) if !rows.is_empty() => {
+                    let parts: Vec<String> = rows
+                        .iter()
+                        .map(|row| {
+                            // Render each row as compact JSON; truncate long values
+                            let s = serde_json::to_string(row).unwrap_or_default();
+                            if s.len() > 60 {
+                                format!("{}…", &s[..60])
+                            } else {
+                                s
+                            }
+                        })
+                        .collect();
+                    let joined = parts.join(", ");
+                    if joined.len() > 120 {
+                        format!("{}…", &joined[..120])
+                    } else {
+                        joined
+                    }
+                }
+                _ => String::new(),
+            };
+            table.add_row([
+                res.name.clone(),
+                format!("{}", res.status),
+                res.violations.to_string(),
+                res.total_rows.to_string(),
+                format!("{:.1}%", res.violation_rate * 100.0),
+                sample_str,
+            ]);
+        } else {
+            table.add_row([
+                res.name.clone(),
+                format!("{}", res.status),
+                res.violations.to_string(),
+                res.total_rows.to_string(),
+                format!("{:.1}%", res.violation_rate * 100.0),
+            ]);
+        }
     });
     table.to_string()
 }