Add --mode flag for CLI output control (text/json/rpc)

- text mode: only outputs final assistant message text (default)
- json mode: streams all events as JSON (same as session manager writes)
- rpc mode: JSON output + listens for JSON input on stdin for headless operation
- Suppress informational messages in json/rpc modes

package-lock.json

@@ -500,6 +500,13 @@
 			"dev": true,
 			"license": "MIT"
 		},
+		"node_modules/@types/diff": {
+			"version": "7.0.2",
+			"resolved": "https://registry.npmjs.org/@types/diff/-/diff-7.0.2.tgz",
+			"integrity": "sha512-JSWRMozjFKsGlEjiiKajUjIJVKuKdE3oVy2DNtK+fUo8q82nhFZ2CPQwicAIkXrofahDXrWJ7mjelvZphMS98Q==",
+			"dev": true,
+			"license": "MIT"
+		},
 		"node_modules/@types/estree": {
 			"version": "1.0.8",
 			"dev": true,
@@ -1102,7 +1109,8 @@
 		},
 		"node_modules/diff": {
 			"version": "8.0.2",
-			"dev": true,
+			"resolved": "https://registry.npmjs.org/diff/-/diff-8.0.2.tgz",
+			"integrity": "sha512-sSuxWU5j5SR9QQji/o2qMvqRNYRDOcBTgsJ/DeCf4iSN4gW+gNMXM7wFIP+fdXZxoNiAnHUTGjCr+TSWXdRDKg==",
 			"license": "BSD-3-Clause",
 			"engines": {
 				"node": ">=0.3.1"
@@ -3262,12 +3270,13 @@
 		},
 		"packages/coding-agent": {
 			"name": "@mariozechner/coding-agent",
-			"version": "0.6.0",
+			"version": "0.6.1",
 			"license": "MIT",
 			"dependencies": {
 				"@mariozechner/pi-agent": "^0.6.0",
 				"@mariozechner/pi-ai": "^0.6.0",
 				"chalk": "^5.5.0",
+				"diff": "^8.0.2",
 				"glob": "^11.0.3"
 			},
 			"bin": {
@@ -3275,6 +3284,7 @@
 				"pi": "dist/cli.js"
 			},
 			"devDependencies": {
+				"@types/diff": "^7.0.2",
 				"@types/node": "^24.3.0",
 				"typescript": "^5.7.3",
 				"vitest": "^3.2.4"