fix(coding-agent): rehome TITLE_SYSTEM.md discovery and reload it on cwd change

packages/coding-agent/src/main.ts

@@ -67,7 +67,7 @@ import {
 import type { AgentSession } from "./session/agent-session";
 import type { AuthStorage } from "./session/auth-storage";
 import { resolveResumableSession, type SessionInfo, SessionManager } from "./session/session-manager";
-import { resolvePromptInput } from "./system-prompt";
+import { discoverTitleSystemPromptFile, resolvePromptInput } from "./system-prompt";
 import { initTelemetryExport, isTelemetryExportEnabled } from "./telemetry-export";
 import { AUTO_THINKING } from "./thinking";
 import { discoverStartupLspServers, type LspStartupServerInfo } from "./tools";
@@ -721,19 +721,6 @@ function discoverAppendSystemPromptFile(): string | undefined {
 	return undefined;
 }
 
-/** Discover TITLE_SYSTEM.md file for automatic session-title prompt overrides */
-export function discoverTitleSystemPromptFile(cwd?: string): string | undefined {
-	const projectPath = findConfigFile("TITLE_SYSTEM.md", { user: false, cwd });
-	if (projectPath) {
-		return projectPath;
-	}
-	const globalPath = findConfigFile("TITLE_SYSTEM.md", { user: true, cwd });
-	if (globalPath) {
-		return globalPath;
-	}
-	return undefined;
-}
-
 async function buildSessionOptions(
 	parsed: Args,
 	scopedModels: ScopedModel[],

packages/coding-agent/src/modes/interactive-mode.ts

@@ -78,6 +78,7 @@ import type { ShakeMode } from "../session/shake-types";
 import { BUILTIN_SLASH_COMMAND_RESERVED_NAMES } from "../slash-commands/builtin-registry";
 import { formatDuration } from "../slash-commands/helpers/format";
 import { STTController, type SttState } from "../stt";
+import { discoverTitleSystemPromptFile, resolvePromptInput } from "../system-prompt";
 import type { LspStartupServerInfo } from "../tools";
 import { normalizeLocalScheme } from "../tools/path-utils";
 import { setAutoQaConsentHandler } from "../tools/report-tool-issue";
@@ -684,6 +685,13 @@ export class InteractiveMode implements InteractiveModeContext {
 		this.updateEditorTopBorder();
 	}
 
+	/** Reload the title-generation system prompt override for the provided working directory. */
+	async refreshTitleSystemPrompt(cwd?: string): Promise<void> {
+		const basePath = cwd ?? this.sessionManager.getCwd();
+		const titleSystemPromptSource = discoverTitleSystemPromptFile(basePath);
+		this.titleSystemPrompt = await resolvePromptInput(titleSystemPromptSource, "title system prompt");
+	}
+
 	/** Reload slash commands and autocomplete for the provided working directory. */
 	async refreshSlashCommandState(cwd?: string): Promise<void> {
 		const basePath = cwd ?? this.sessionManager.getCwd();
@@ -718,6 +726,7 @@ export class InteractiveMode implements InteractiveModeContext {
 		// Re-warm plugin roots, capabilities, slash commands, and the ssh tool so
 		// the next prompt sees everything scoped to the new project directory.
 		clearClaudePluginRootsCache();
+		await this.refreshTitleSystemPrompt(newCwd);
 		resetCapabilities();
 		await this.refreshSlashCommandState(newCwd);
 		await this.session.refreshSshTool({ activateIfAvailable: true });

packages/coding-agent/src/system-prompt.ts

@@ -8,6 +8,7 @@ import { $env, getGpuCachePath, getProjectDir, hasFsCode, isEnoent, logger, prom
 import { $ } from "bun";
 import { contextFileCapability } from "./capability/context-file";
 import { systemPromptCapability } from "./capability/system-prompt";
+import { findConfigFile } from "./config";
 import type { SkillsSettings } from "./config/settings";
 import { type ContextFile, loadCapability, type SystemPrompt as SystemPromptFile } from "./discovery";
 import { expandAtImports } from "./discovery/at-imports";
@@ -208,6 +209,19 @@ async function getEnvironmentInfo(): Promise<Array<{ label: string; value: strin
 	return entries.filter((e): e is { label: string; value: string } => !!e.value);
 }
 
+/** Discover TITLE_SYSTEM.md file for automatic session-title prompt overrides */
+export function discoverTitleSystemPromptFile(cwd?: string): string | undefined {
+	const projectPath = findConfigFile("TITLE_SYSTEM.md", { user: false, cwd });
+	if (projectPath) {
+		return projectPath;
+	}
+	const globalPath = findConfigFile("TITLE_SYSTEM.md", { user: true, cwd });
+	if (globalPath) {
+		return globalPath;
+	}
+	return undefined;
+}
+
 /** Resolve input as file path or literal string */
 export async function resolvePromptInput(input: string | undefined, description: string): Promise<string | undefined> {
 	if (!input) {