feat(cli): add --append-system-prompt option

.changeset/append-system-prompt-cli.md

@@ -0,0 +1,6 @@
+---
+"@kilocode/cli": patch
+"kilo-code": patch
+---
+
+Add `--append-system-prompt` CLI option to append custom instructions to the system prompt

cli/src/__tests__/append-system-prompt.test.ts

@@ -0,0 +1,109 @@
+import { describe, it, expect } from "vitest"
+import type { CLIOptions } from "../types/cli.js"
+
+describe("Append System Prompt CLI Option", () => {
+	describe("CLIOptions type", () => {
+		it("should accept appendSystemPrompt as a string option", () => {
+			const options: CLIOptions = {
+				mode: "code",
+				workspace: "/test/workspace",
+				appendSystemPrompt: "Custom instructions here",
+			}
+
+			expect(options.appendSystemPrompt).toBe("Custom instructions here")
+		})
+
+		it("should allow appendSystemPrompt to be undefined", () => {
+			const options: CLIOptions = {
+				mode: "code",
+				workspace: "/test/workspace",
+			}
+
+			expect(options.appendSystemPrompt).toBeUndefined()
+		})
+
+		it("should handle empty string for appendSystemPrompt", () => {
+			const options: CLIOptions = {
+				mode: "code",
+				workspace: "/test/workspace",
+				appendSystemPrompt: "",
+			}
+
+			expect(options.appendSystemPrompt).toBe("")
+		})
+
+		it("should handle multi-line appendSystemPrompt", () => {
+			const multiLinePrompt = `Line 1
+Line 2
+Line 3`
+			const options: CLIOptions = {
+				mode: "code",
+				workspace: "/test/workspace",
+				appendSystemPrompt: multiLinePrompt,
+			}
+
+			expect(options.appendSystemPrompt).toBe(multiLinePrompt)
+		})
+	})
+
+	describe("CLI flag parsing", () => {
+		it("should parse --append-system-prompt flag with value", () => {
+			// This test validates the expected behavior when the flag is parsed
+			const mockArgs = ["--append-system-prompt", "Custom instructions"]
+			const expectedValue = "Custom instructions"
+
+			// Simulate what commander.js would do
+			const parsedValue = mockArgs[1]
+			expect(parsedValue).toBe(expectedValue)
+		})
+
+		it("should handle --append-system-prompt with quoted multi-word value", () => {
+			const mockArgs = ["--append-system-prompt", "Always use TypeScript strict mode"]
+			const expectedValue = "Always use TypeScript strict mode"
+
+			const parsedValue = mockArgs[1]
+			expect(parsedValue).toBe(expectedValue)
+		})
+	})
+
+	describe("System prompt integration", () => {
+		it("should append custom text to system prompt when provided", () => {
+			const basePrompt = "You are Kilo Code, an AI assistant."
+			const appendText = "Always write tests first."
+			const expectedPrompt = `${basePrompt}
+
+${appendText}`
+
+			const result = `${basePrompt}\n\n${appendText}`
+			expect(result).toBe(expectedPrompt)
+		})
+
+		it("should not modify system prompt when appendSystemPrompt is undefined", () => {
+			const basePrompt = "You are Kilo Code, an AI assistant."
+			const appendText = undefined
+
+			const result = appendText ? `${basePrompt}\n\n${appendText}` : basePrompt
+			expect(result).toBe(basePrompt)
+		})
+
+		it("should not modify system prompt when appendSystemPrompt is empty string", () => {
+			const basePrompt = "You are Kilo Code, an AI assistant."
+			const appendText = ""
+
+			const result = appendText ? `${basePrompt}\n\n${appendText}` : basePrompt
+			expect(result).toBe(basePrompt)
+		})
+
+		it("should properly format appended text with newlines", () => {
+			const basePrompt = "You are Kilo Code."
+			const appendText = "Rule 1: Test first\nRule 2: Keep it simple"
+			const expectedPrompt = `You are Kilo Code.
+
+Rule 1: Test first
+Rule 2: Keep it simple`
+
+			const result = `${basePrompt}\n\n${appendText}`
+			expect(result).toBe(expectedPrompt)
+		})
+	})
+})

cli/src/cli.ts

@@ -117,6 +117,10 @@ export class CLI {
 				serviceOptions.customModes = this.options.customModes
 			}
 
+			if (this.options.appendSystemPrompt) {
+				serviceOptions.appendSystemPrompt = this.options.appendSystemPrompt
+			}
+
 			this.service = createExtensionService(serviceOptions)
 			logs.debug("ExtensionService created with identity", "CLI", {
 				hasIdentity: !!identity,

cli/src/host/ExtensionHost.ts

@@ -11,6 +11,7 @@ export interface ExtensionHostOptions {
 	extensionRootPath: string // Root path for extension assets
 	identity?: IdentityInfo // Identity information for VSCode environment
 	customModes?: ModeConfig[] // Custom modes configuration
+	appendSystemPrompt?: string // Custom text to append to system prompt
 }
 
 // Extension module interface
@@ -786,6 +787,8 @@ export class ExtensionHost extends EventEmitter {
 				imageGeneration: false,
 				runSlashCommand: false,
 			},
+			// Add appendSystemPrompt from CLI options
+			...(this.options.appendSystemPrompt && { appendSystemPrompt: this.options.appendSystemPrompt }),
 		}
 
 		// The CLI will inject the actual configuration through updateState
@@ -1037,6 +1040,20 @@ export class ExtensionHost extends EventEmitter {
 				settings: Object.keys(autoApprovalSettings),
 			})
 		}
+
+		// Sync appendSystemPrompt to extension
+		// This setting is passed from CLI options and needs to be stored in the extension's
+		// contextProxy so it's available when generating the system prompt
+		const appendSystemPrompt = configState.appendSystemPrompt || this.options.appendSystemPrompt
+		if (appendSystemPrompt) {
+			await this.sendWebviewMessage({
+				type: "updateSettings",
+				updatedSettings: { appendSystemPrompt },
+			})
+			logs.debug("appendSystemPrompt synchronized to extension", "ExtensionHost", {
+				length: appendSystemPrompt.length,
+			})
+		}
 	}
 
 	/**

cli/src/index.ts

@@ -48,6 +48,7 @@ program
 	.option("-s, --session <sessionId>", "Restore a session by ID")
 	.option("-f, --fork <shareId>", "Fork a session by ID")
 	.option("--nosplash", "Disable the welcome message and update notifications", false)
+	.option("--append-system-prompt <text>", "Append custom instructions to the system prompt")
 	.argument("[prompt]", "The prompt or command to execute")
 	.action(async (prompt, options) => {
 		// Validate that --existing-branch requires --parallel
@@ -228,6 +229,7 @@ program
 			session: options.session,
 			fork: options.fork,
 			noSplash: options.nosplash,
+			appendSystemPrompt: options.appendSystemPrompt,
 		})
 		await cli.start()
 		await cli.dispose()

cli/src/services/extension.ts

@@ -22,6 +22,8 @@ export interface ExtensionServiceOptions {
 	extensionRootPath?: string
 	/** Identity information for VSCode environment */
 	identity?: IdentityInfo
+	/** Custom text to append to system prompt */
+	appendSystemPrompt?: string
 }
 
 /**
@@ -73,9 +75,10 @@ export interface ExtensionServiceEvents {
 export class ExtensionService extends EventEmitter {
 	private extensionHost: ExtensionHost
 	private messageBridge: MessageBridge
-	private options: Required<Omit<ExtensionServiceOptions, "identity" | "customModes">> & {
+	private options: Required<Omit<ExtensionServiceOptions, "identity" | "customModes" | "appendSystemPrompt">> & {
 		identity?: IdentityInfo
 		customModes?: ModeConfig[]
+		appendSystemPrompt?: string
 	}
 	private isInitialized = false
 	private isDisposed = false
@@ -95,6 +98,7 @@ export class ExtensionService extends EventEmitter {
 			extensionRootPath: options.extensionRootPath || extensionPaths.extensionRootPath,
 			...(options.identity && { identity: options.identity }),
 			...(options.customModes && { customModes: options.customModes }),
+			...(options.appendSystemPrompt && { appendSystemPrompt: options.appendSystemPrompt }),
 		}
 
 		// Create extension host
@@ -109,6 +113,9 @@ export class ExtensionService extends EventEmitter {
 		if (this.options.customModes) {
 			hostOptions.customModes = this.options.customModes
 		}
+		if (this.options.appendSystemPrompt) {
+			hostOptions.appendSystemPrompt = this.options.appendSystemPrompt
+		}
 		this.extensionHost = createExtensionHost(hostOptions)
 
 		// Create message bridge

cli/src/types/cli.ts

@@ -43,4 +43,5 @@ export interface CLIOptions {
 	session?: string
 	fork?: string
 	noSplash?: boolean
+	appendSystemPrompt?: string
 }

cli/src/types/messages.ts

@@ -87,6 +87,7 @@ export interface ExtensionState {
 	cwd?: string
 	organizationAllowList?: OrganizationAllowList
 	routerModels?: RouterModels
+	appendSystemPrompt?: string // Custom text to append to system prompt (CLI only)
 	[key: string]: unknown
 }
 

packages/types/src/global-settings.ts

@@ -235,6 +235,7 @@ export const globalSettingsSchema = z.object({
 	hasOpenedModeSelector: z.boolean().optional(),
 	lastModeExportPath: z.string().optional(),
 	lastModeImportPath: z.string().optional(),
+	appendSystemPrompt: z.string().optional(), // kilocode_change: Custom text to append to system prompt (CLI only)
 })
 
 export type GlobalSettings = z.infer<typeof globalSettingsSchema>

src/core/prompts/system.ts

@@ -156,6 +156,13 @@ ${await addCustomInstructions(baseInstructions, globalCustomInstructions || "",
 	settings,
 })}`
 
+	// kilocode_change start: Append custom system prompt from CLI if provided
+	const appendSystemPrompt = clineProviderState?.appendSystemPrompt
+	if (appendSystemPrompt) {
+		return `${basePrompt}\n\n${appendSystemPrompt}`
+	}
+	// kilocode_change end
+
 	return basePrompt
 }
 

src/core/webview/ClineProvider.ts

@@ -2705,6 +2705,7 @@ export class ClineProvider
 					return false
 				}
 			})(),
+			appendSystemPrompt: stateValues.appendSystemPrompt, // kilocode_change: CLI append system prompt
 		}
 	}
 

src/shared/ExtensionMessage.ts

@@ -543,6 +543,7 @@ export type ExtensionState = Pick<
 	showTimestamps?: boolean // kilocode_change: Show timestamps in chat messages
 	debug?: boolean
 	speechToTextStatus?: { available: boolean; reason?: "openaiKeyMissing" | "ffmpegNotInstalled" } // kilocode_change: Speech-to-text availability status with failure reason
+	appendSystemPrompt?: string // kilocode_change: Custom text to append to system prompt (CLI only)
 }
 
 export interface ClineSayTool {