dean0x · dean0x · Mar 28, 2026 · Mar 28, 2026 · Mar 28, 2026 · Mar 28, 2026
@@ -39,6 +39,7 @@ pub(crate) enum CommandType {
     Test,
     Build,
     Git,
+    Lint,
 }
 
 impl CommandType {
@@ -48,6 +49,7 @@ impl CommandType {
             CommandType::Test => "test",
             CommandType::Build => "build",
             CommandType::Git => "git",
+            CommandType::Lint => "lint",
         }
     }
 }

@@ -0,0 +1,278 @@
+//! ESLint parser with three-tier degradation (#104).
+//!
+//! Executes `eslint` and parses the output into a structured `LintResult`.
+//!
+//! Three tiers:
+//! - **Tier 1 (Full)**: JSON array parsing (`--format json`)
+//! - **Tier 2 (Degraded)**: Regex on default formatter output
+//! - **Tier 3 (Passthrough)**: Raw stdout+stderr concatenation
+
+use std::sync::LazyLock;
+
+use regex::Regex;
+
+use crate::cmd::user_has_flag;
+use crate::output::canonical::{LintIssue, LintResult, LintSeverity};
+use crate::output::ParseResult;
+use crate::runner::CommandOutput;
+
+use super::{combine_stdout_stderr, group_issues, LinterConfig};
+
+const CONFIG: LinterConfig<'static> = LinterConfig {
+    program: "eslint",
+    env_overrides: &[("NO_COLOR", "1")],
+    install_hint: "Install eslint via npm: npm install -g eslint",
+};
+
+// Static regex patterns compiled once via LazyLock.
+static RE_ESLINT_LINE: LazyLock<Regex> = LazyLock::new(|| {
+    // Matches: "  12:7  warning  'x' is defined but never used  no-unused-vars"
+    Regex::new(r"^\s+(\d+):\d+\s+(error|warning)\s+(.+?)\s{2,}(\S+)\s*$").unwrap()
+});
+
+static RE_ESLINT_FILE: LazyLock<Regex> =
+    LazyLock::new(|| Regex::new(r"^(/[^\s]+|[A-Z]:\\[^\s]+)$").unwrap());
+
+/// Run `skim lint eslint [args...]`.
+pub(crate) fn run(
+    args: &[String],
+    show_stats: bool,
+    json_output: bool,
+) -> anyhow::Result<std::process::ExitCode> {
+    super::run_linter(
+        CONFIG,
+        args,
+        show_stats,
+        json_output,
+        prepare_args,
+        parse_impl,
+    )
+}
+
+/// Inject `--format json` if not already present.
+fn prepare_args(cmd_args: &mut Vec<String>) {
+    if !user_has_flag(cmd_args, &["--format", "-f"]) {
+        cmd_args.insert(0, "json".to_string());
+        cmd_args.insert(0, "--format".to_string());
+    }
+}
+
+/// Three-tier parse function for eslint output.
+fn parse_impl(output: &CommandOutput) -> ParseResult<LintResult> {
+    if let Some(result) = try_parse_json(&output.stdout) {
+        return ParseResult::Full(result);
+    }
+
+    let combined = combine_stdout_stderr(output);
+
+    if let Some(result) = try_parse_regex(&combined) {
+        return ParseResult::Degraded(result, vec!["regex fallback".to_string()]);
+    }
+
+    ParseResult::Passthrough(combined.into_owned())
+}
+
+// ============================================================================
+// Tier 1: JSON parsing
+// ============================================================================
+
+/// Parse eslint JSON output format.
+///
+/// ESLint `--format json` produces an array of file results:
+/// ```json
+/// [{"filePath": "...", "messages": [{"ruleId": "...", "severity": 1, "message": "...", "line": 12}]}]
+/// ```
+fn try_parse_json(stdout: &str) -> Option<LintResult> {
+    let arr: Vec<serde_json::Value> = serde_json::from_str(stdout.trim()).ok()?;
+
+    let mut issues: Vec<LintIssue> = Vec::new();
+
+    for file_entry in &arr {
+        let Some(file_path) = file_entry.get("filePath").and_then(|v| v.as_str()) else {
+            continue;
+        };
+        let Some(messages) = file_entry.get("messages").and_then(|v| v.as_array()) else {
+            continue;
+        };
+
+        for msg in messages {
+            let Some(severity_num) = msg.get("severity").and_then(|v| v.as_u64()) else {
+                continue;
+            };
+            let severity = match severity_num {
+                2 => LintSeverity::Error,
+                1 => LintSeverity::Warning,
+                _ => LintSeverity::Info,
+            };
+            let rule_id = msg
+                .get("ruleId")
+                .and_then(|v| v.as_str())
+                .unwrap_or("(unknown)");
+            let Some(message) = msg.get("message").and_then(|v| v.as_str()) else {
+                continue;
+            };
+            let Some(line) = msg.get("line").and_then(|v| v.as_u64()) else {
+                continue;
+            };
+
+            issues.push(LintIssue {
+                file: file_path.to_string(),
+                line: u32::try_from(line).unwrap_or(u32::MAX),
+                rule: rule_id.to_string(),
+                message: message.to_string(),
+                severity,
+            });
+        }
+    }
+
+    Some(group_issues("eslint", issues))
+}
+
+// ============================================================================
+// Tier 2: regex fallback
+// ============================================================================
+
+/// Parse eslint default formatter output via regex.
+///
+/// Format:
+/// ```text
+/// /path/to/file.ts
+///   12:7  warning  'x' is defined but never used  no-unused-vars
+/// ```
+fn try_parse_regex(text: &str) -> Option<LintResult> {
+    let mut issues: Vec<LintIssue> = Vec::new();
+    let mut current_file = String::new();
+
+    for line in text.lines() {
+        // Try to match a file path line
+        if RE_ESLINT_FILE.is_match(line.trim()) {
+            current_file = line.trim().to_string();
+            continue;
+        }
+
+        // Try to match an issue line
+        if let Some(caps) = RE_ESLINT_LINE.captures(line) {
+            let line_num: u32 = caps[1].parse().unwrap_or(0);
+            let severity = match &caps[2] {
+                "error" => LintSeverity::Error,
+                "warning" => LintSeverity::Warning,
+                _ => LintSeverity::Info,
+            };
+            let message = caps[3].to_string();
+            let rule = caps[4].to_string();
+
+            issues.push(LintIssue {
+                file: current_file.clone(),
+                line: line_num,
+                rule,
+                message,
+                severity,
+            });
+        }
+    }
+
+    if issues.is_empty() {
+        return None;
+    }
+
+    Some(group_issues("eslint", issues))
+}
+
+// ============================================================================
+// Unit tests
+// ============================================================================
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn load_fixture(name: &str) -> String {
+        let mut path = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+        path.push("tests/fixtures/cmd/lint");
+        path.push(name);
+        std::fs::read_to_string(&path)
+            .unwrap_or_else(|e| panic!("Failed to load fixture '{name}': {e}"))
+    }
+
+    #[test]
+    fn test_tier1_eslint_pass() {
+        let input = load_fixture("eslint_pass.json");
+        let result = try_parse_json(&input);
+        assert!(result.is_some(), "Expected Tier 1 JSON parse to succeed");
+        let result = result.unwrap();
+        assert_eq!(result.errors, 0);
+        assert_eq!(result.warnings, 0);
+        assert!(result.as_ref().contains("LINT OK"));
+    }
+
+    #[test]
+    fn test_tier1_eslint_fail() {
+        let input = load_fixture("eslint_fail.json");
+        let result = try_parse_json(&input);
+        assert!(result.is_some(), "Expected Tier 1 JSON parse to succeed");
+        let result = result.unwrap();
+        assert_eq!(result.errors, 2);
+        assert_eq!(result.warnings, 3);
+        assert!(result.groups.len() >= 2, "Expected at least 2 rule groups");
+    }
+
+    #[test]
+    fn test_tier2_eslint_regex() {
+        let input = load_fixture("eslint_text.txt");
+        let result = try_parse_regex(&input);
+        assert!(result.is_some(), "Expected Tier 2 regex parse to succeed");
+        let result = result.unwrap();
+        assert_eq!(result.errors, 2);
+        assert_eq!(result.warnings, 2);
+    }
+
+    #[test]
+    fn test_parse_impl_json_produces_full() {
+        let input = load_fixture("eslint_fail.json");
+        let output = CommandOutput {
+            stdout: input,
+            stderr: String::new(),
+            exit_code: Some(1),
+            duration: std::time::Duration::ZERO,
+        };
+        let result = parse_impl(&output);
+        assert!(
+            result.is_full(),
+            "Expected Full parse result, got {}",
+            result.tier_name()
+        );
+    }
+
+    #[test]
+    fn test_parse_impl_text_produces_degraded() {
+        let input = load_fixture("eslint_text.txt");
+        let output = CommandOutput {
+            stdout: input,
+            stderr: String::new(),
+            exit_code: Some(1),
+            duration: std::time::Duration::ZERO,
+        };
+        let result = parse_impl(&output);
+        assert!(
+            result.is_degraded(),
+            "Expected Degraded parse result, got {}",
+            result.tier_name()
+        );
+    }
+
+    #[test]
+    fn test_parse_impl_garbage_produces_passthrough() {
+        let output = CommandOutput {
+            stdout: "completely unparseable output\nno json, no regex match".to_string(),
+            stderr: String::new(),
+            exit_code: Some(1),
+            duration: std::time::Duration::ZERO,
+        };
+        let result = parse_impl(&output);
+        assert!(
+            result.is_passthrough(),
+            "Expected Passthrough, got {}",
+            result.tier_name()
+        );
+    }
+}