feat(coding-agent/lsp): added SwiftLint linter client with JSON reporter and bash.virtualTerminal setting

- Added SwiftLint linter client with JSON reporter support for Swift file linting.
- Changed SwiftLint configuration to use 'lint' command with JSON reporter for structured output.
- Changed bash.virtualTerminal default setting from 'on' to 'off' for standard non-interactive execution.
- Implemented SwiftLintClient with lint() method that executes swiftlint with JSON output and converts violations to LSP diagnostics.
- Added bash.virtualTerminal settings option with 'on' (PTY-backed interactive) and 'off' (standard non-interactive) values.

packages/coding-agent/CHANGELOG.md

@@ -1,9 +1,9 @@
 # Changelog
 
 ## [Unreleased]
-
 ### Added
 
+- Added SwiftLint linter client with JSON reporter support for Swift file linting
 - Added `--no-pty` flag to disable PTY-based interactive bash execution
 - Added `PI_NO_PTY` environment variable to disable PTY-based interactive bash execution
 - Added `bash.virtualTerminal` setting to control PTY-backed interactive execution for bash commands
@@ -12,6 +12,8 @@
 
 ### Changed
 
+- Changed `bash.virtualTerminal` default from `on` to `off` for standard non-interactive bash execution
+- Changed SwiftLint configuration to use `lint` command with JSON reporter instead of `analyze` for improved diagnostic parsing
 - Changed diff line format from space-separated (`+123 content`) to pipe-delimited (`+123|content`) for improved parsing reliability
 - Changed bash tool to use interactive PTY execution by default when UI is available, falling back to standard execution when disabled
 

packages/coding-agent/src/config/settings-schema.ts

@@ -633,7 +633,7 @@ export const SETTINGS_SCHEMA = {
 	"bash.virtualTerminal": {
 		type: "enum",
 		values: ["on", "off"] as const,
-		default: "on",
+		default: "off",
 		ui: {
 			tab: "bash",
 			label: "Virtual terminal",

packages/coding-agent/src/lsp/clients/index.ts

@@ -10,6 +10,7 @@ import { LspLinterClient } from "./lsp-linter-client";
 
 export { BiomeClient } from "./biome-client";
 export { LspLinterClient } from "./lsp-linter-client";
+export { SwiftLintClient } from "./swiftlint-client";
 
 // Cache of linter clients by server name + cwd
 const clientCache = new Map<string, LinterClient>();

packages/coding-agent/src/lsp/clients/swiftlint-client.ts

@@ -0,0 +1,120 @@
+/**
+ * SwiftLint CLI-based linter client.
+ * Parses SwiftLint's JSON reporter output into LSP Diagnostic format.
+ */
+import type { Diagnostic, DiagnosticSeverity, LinterClient, ServerConfig } from "../../lsp/types";
+
+/** Shape of a single violation from `swiftlint lint --reporter json`. */
+interface SwiftLintViolation {
+	character: number;
+	file: string;
+	line: number;
+	reason: string;
+	rule_id: string;
+	severity: "Error" | "Warning";
+	type: string;
+}
+
+function parseSeverity(severity: string): DiagnosticSeverity {
+	switch (severity) {
+		case "Error":
+			return 1;
+		case "Warning":
+			return 2;
+		default:
+			return 2;
+	}
+}
+
+async function runSwiftLint(
+	args: string[],
+	cwd: string,
+	resolvedCommand?: string,
+): Promise<{ stdout: string; stderr: string; success: boolean }> {
+	const command = resolvedCommand ?? "swiftlint";
+
+	try {
+		const proc = Bun.spawn([command, ...args], {
+			cwd,
+			stdout: "pipe",
+			stderr: "pipe",
+			windowsHide: true,
+		});
+
+		const [stdout, stderr] = await Promise.all([new Response(proc.stdout).text(), new Response(proc.stderr).text()]);
+		await proc.exited;
+
+		// swiftlint exits non-zero when violations found — that's not a failure
+		return { stdout, stderr, success: stdout.length > 0 };
+	} catch (err) {
+		return { stdout: "", stderr: String(err), success: false };
+	}
+}
+
+/**
+ * SwiftLint CLI-based linter client.
+ * Runs `swiftlint lint --reporter json` and converts violations to LSP diagnostics.
+ */
+export class SwiftLintClient implements LinterClient {
+	/** Factory method for creating SwiftLintClient instances */
+	static create(config: ServerConfig, cwd: string): LinterClient {
+		return new SwiftLintClient(config, cwd);
+	}
+
+	constructor(
+		private readonly config: ServerConfig,
+		private readonly cwd: string,
+	) {}
+
+	async format(_filePath: string, content: string): Promise<string> {
+		// SwiftLint doesn't support formatting
+		return content;
+	}
+
+	async lint(filePath: string): Promise<Diagnostic[]> {
+		const result = await runSwiftLint(
+			["lint", "--quiet", "--reporter", "json", filePath],
+			this.cwd,
+			this.config.resolvedCommand,
+		);
+
+		if (!result.success) {
+			return [];
+		}
+
+		return this.#parseJsonOutput(result.stdout);
+	}
+
+	#parseJsonOutput(jsonOutput: string): Diagnostic[] {
+		const diagnostics: Diagnostic[] = [];
+
+		try {
+			const violations: SwiftLintViolation[] = JSON.parse(jsonOutput);
+
+			for (const v of violations) {
+				// SwiftLint lines/characters are 1-based; LSP is 0-based
+				const line = Math.max(0, v.line - 1);
+				const character = Math.max(0, v.character - 1);
+
+				diagnostics.push({
+					range: {
+						start: { line, character },
+						end: { line, character },
+					},
+					severity: parseSeverity(v.severity),
+					message: v.reason,
+					source: "swiftlint",
+					code: v.rule_id,
+				});
+			}
+		} catch {
+			// JSON parse failed, return empty
+		}
+
+		return diagnostics;
+	}
+
+	dispose(): void {
+		// Nothing to dispose for CLI client
+	}
+}

packages/coding-agent/src/lsp/config.ts

@@ -6,6 +6,7 @@ import { YAML } from "bun";
 import { globSync } from "glob";
 import { getConfigDirPaths } from "../config";
 import { BiomeClient } from "./clients/biome-client";
+import { SwiftLintClient } from "./clients/swiftlint-client";
 import DEFAULTS from "./defaults.json" with { type: "json" };
 import type { ServerConfig } from "./types";
 
@@ -137,6 +138,10 @@ function applyRuntimeDefaults(servers: Record<string, ServerConfig>): Record<str
 		updated.biome = { ...updated.biome, createClient: BiomeClient.create };
 	}
 
+	if (updated.swiftlint) {
+		updated.swiftlint = { ...updated.swiftlint, createClient: SwiftLintClient.create };
+	}
+
 	if (updated.omnisharp?.args) {
 		const args = updated.omnisharp.args.map(arg => (arg === PID_TOKEN ? String(process.pid) : arg));
 		updated.omnisharp = { ...updated.omnisharp, args };

packages/coding-agent/src/lsp/defaults.json

@@ -456,7 +456,7 @@
 	},
 	"swiftlint": {
 		"command": "swiftlint",
-		"args": ["analyze", "--quiet"],
+		"args": ["lint", "--quiet", "--reporter", "json"],
 		"fileTypes": [".swift"],
 		"rootMarkers": [".swiftlint.yml", ".swiftlint.yaml", "Package.swift", "*.xcodeproj"],
 		"isLinter": true

packages/coding-agent/src/modes/components/settings-defs.ts

@@ -139,6 +139,11 @@ const OPTION_PROVIDERS: Partial<Record<SettingPath, OptionProvider>> = {
 		{ value: "20", label: "20 messages" },
 		{ value: "30", label: "30 messages" },
 	],
+	// Virtual terminal
+	"bash.virtualTerminal": [
+		{ value: "on", label: "On", description: "PTY-backed interactive execution" },
+		{ value: "off", label: "Off", description: "Standard non-interactive execution" },
+	],
 	// Provider options
 	"providers.webSearch": [
 		{ value: "auto", label: "Auto", description: "Priority: Exa > Perplexity > Anthropic" },