From d5e0cb463088716118220e2a66a4ac8fb12435e7 Mon Sep 17 00:00:00 2001
From: Hew Li Yang <hewliyang@u.nus.edu>
Date: Fri, 5 Dec 2025 18:47:57 +0800
Subject: [PATCH] wip: add /resume slash command

---
 packages/coding-agent/README.md               | 10 +++
 packages/coding-agent/src/tui/tui-renderer.ts | 64 +++++++++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/packages/coding-agent/README.md b/packages/coding-agent/README.md
index ec4809fc..630fc48b 100644
--- a/packages/coding-agent/README.md
+++ b/packages/coding-agent/README.md
@@ -502,6 +502,16 @@ This allows you to explore alternative conversation paths without losing your cu
 /branch
 ```
 
+### /resume
+
+Switch to a different session. Opens an interactive selector showing all available sessions. Select a session to load it and continue where you left off.
+
+This is equivalent to the `--resume` CLI flag but can be used mid-session.
+
+```
+/resume
+```
+
 ### /login
 
 Login with OAuth to use subscription-based models (Claude Pro/Max):
diff --git a/packages/coding-agent/src/tui/tui-renderer.ts b/packages/coding-agent/src/tui/tui-renderer.ts
index 13e66778..6254ec45 100644
--- a/packages/coding-agent/src/tui/tui-renderer.ts
+++ b/packages/coding-agent/src/tui/tui-renderer.ts
@@ -42,6 +42,7 @@ import { FooterComponent } from "./footer.js";
 import { ModelSelectorComponent } from "./model-selector.js";
 import { OAuthSelectorComponent } from "./oauth-selector.js";
 import { QueueModeSelectorComponent } from "./queue-mode-selector.js";
+import { SessionSelectorComponent } from "./session-selector.js";
 import { ThemeSelectorComponent } from "./theme-selector.js";
 import { ThinkingSelectorComponent } from "./thinking-selector.js";
 import { ToolExecutionComponent } from "./tool-execution.js";
@@ -95,6 +96,9 @@ export class TuiRenderer {
 	// User message selector (for branching)
 	private userMessageSelector: UserMessageSelectorComponent | null = null;
 
+	// Session selector (for resume)
+	private sessionSelector: SessionSelectorComponent | null = null;
+
 	// OAuth selector
 	private oauthSelector: any | null = null;
 
@@ -214,6 +218,11 @@ export class TuiRenderer {
 			description: "Toggle automatic context compaction",
 		};
 
+		const resumeCommand: SlashCommand = {
+			name: "resume",
+			description: "Resume a different session",
+		};
+
 		// Load hide thinking block setting
 		this.hideThinkingBlock = settingsManager.getHideThinkingBlock();
 
@@ -243,6 +252,7 @@ export class TuiRenderer {
 				clearCommand,
 				compactCommand,
 				autocompactCommand,
+				resumeCommand,
 				...fileSlashCommands,
 			],
 			process.cwd(),
@@ -488,6 +498,13 @@ export class TuiRenderer {
 				return;
 			}
 
+			// Check for /resume command
+			if (text === "/resume") {
+				this.showSessionSelector();
+				this.editor.setText("");
+				return;
+			}
+
 			// Check for file-based slash commands
 			text = expandSlashCommand(text, this.fileCommands);
 
@@ -1468,6 +1485,53 @@ export class TuiRenderer {
 		this.ui.setFocus(this.editor);
 	}
 
+	private showSessionSelector(): void {
+		// Create session selector
+		this.sessionSelector = new SessionSelectorComponent(
+			this.sessionManager,
+			(sessionPath) => {
+				// Set the selected session as active
+				this.sessionManager.setSessionFile(sessionPath);
+
+				// Reload the session
+				const loaded = loadSessionFromEntries(this.sessionManager.loadEntries());
+				this.agent.replaceMessages(loaded.messages);
+
+				// Clear and re-render the chat
+				this.chatContainer.clear();
+				this.isFirstUserMessage = true;
+				this.renderInitialMessages(this.agent.state);
+
+				// Show confirmation message
+				this.chatContainer.addChild(new Spacer(1));
+				this.chatContainer.addChild(new Text(theme.fg("dim", "Resumed session"), 1, 0));
+
+				// Hide selector and show editor again
+				this.hideSessionSelector();
+				this.ui.requestRender();
+			},
+			() => {
+				// Just hide the selector
+				this.hideSessionSelector();
+				this.ui.requestRender();
+			},
+		);
+
+		// Replace editor with selector
+		this.editorContainer.clear();
+		this.editorContainer.addChild(this.sessionSelector);
+		this.ui.setFocus(this.sessionSelector.getSessionList());
+		this.ui.requestRender();
+	}
+
+	private hideSessionSelector(): void {
+		// Replace selector with editor in the container
+		this.editorContainer.clear();
+		this.editorContainer.addChild(this.editor);
+		this.sessionSelector = null;
+		this.ui.setFocus(this.editor);
+	}
+
 	private async showOAuthSelector(mode: "login" | "logout"): Promise<void> {
 		// For logout mode, filter to only show logged-in providers
 		let providersToShow: string[] = [];