diff --git a/.pi/extensions/files.ts b/.pi/extensions/files.ts
new file mode 100644
index 00000000..88864f5b
--- /dev/null
+++ b/.pi/extensions/files.ts
@@ -0,0 +1,173 @@
+/**
+ * Files Extension
+ *
+ * /files command lists all files the model has read/written/edited in the active session branch,
+ * coalesced by path and sorted newest first. Selecting a file opens it in VS Code.
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+import { DynamicBorder } from "@mariozechner/pi-coding-agent";
+import { Container, Key, matchesKey, type SelectItem, SelectList, Text } from "@mariozechner/pi-tui";
+
+interface FileEntry {
+	path: string;
+	operations: Set<"read" | "write" | "edit">;
+	lastTimestamp: number;
+}
+
+type FileToolName = "read" | "write" | "edit";
+
+export default function (pi: ExtensionAPI) {
+	pi.registerCommand("files", {
+		description: "Show files read/written/edited in this session",
+		handler: async (_args, ctx) => {
+			if (!ctx.hasUI) {
+				ctx.ui.notify("No UI available", "error");
+				return;
+			}
+
+			// Get the current branch (path from leaf to root)
+			const branch = ctx.sessionManager.getBranch();
+
+			// First pass: collect tool calls (id -> {path, name}) from assistant messages
+			const toolCalls = new Map<string, { path: string; name: FileToolName; timestamp: number }>();
+
+			for (const entry of branch) {
+				if (entry.type !== "message") continue;
+				const msg = entry.message;
+
+				if (msg.role === "assistant" && Array.isArray(msg.content)) {
+					for (const block of msg.content) {
+						if (block.type === "toolCall") {
+							const name = block.name;
+							if (name === "read" || name === "write" || name === "edit") {
+								const path = block.arguments?.path;
+								if (path && typeof path === "string") {
+									toolCalls.set(block.id, { path, name, timestamp: msg.timestamp });
+								}
+							}
+						}
+					}
+				}
+			}
+
+			// Second pass: match tool results to get the actual execution timestamp
+			const fileMap = new Map<string, FileEntry>();
+
+			for (const entry of branch) {
+				if (entry.type !== "message") continue;
+				const msg = entry.message;
+
+				if (msg.role === "toolResult") {
+					const toolCall = toolCalls.get(msg.toolCallId);
+					if (!toolCall) continue;
+
+					const { path, name } = toolCall;
+					const timestamp = msg.timestamp;
+
+					const existing = fileMap.get(path);
+					if (existing) {
+						existing.operations.add(name);
+						if (timestamp > existing.lastTimestamp) {
+							existing.lastTimestamp = timestamp;
+						}
+					} else {
+						fileMap.set(path, {
+							path,
+							operations: new Set([name]),
+							lastTimestamp: timestamp,
+						});
+					}
+				}
+			}
+
+			if (fileMap.size === 0) {
+				ctx.ui.notify("No files read/written/edited in this session", "info");
+				return;
+			}
+
+			// Sort by most recent first
+			const files = Array.from(fileMap.values()).sort((a, b) => b.lastTimestamp - a.lastTimestamp);
+
+			const openSelected = async (file: FileEntry): Promise<void> => {
+				try {
+					await pi.exec("code", ["-g", file.path], { cwd: ctx.cwd });
+				} catch (error) {
+					const message = error instanceof Error ? error.message : String(error);
+					ctx.ui.notify(`Failed to open ${file.path}: ${message}`, "error");
+				}
+			};
+
+			// Show file picker with SelectList
+			await ctx.ui.custom<void>((tui, theme, _kb, done) => {
+				const container = new Container();
+
+				// Top border
+				container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
+
+				// Title
+				container.addChild(new Text(theme.fg("accent", theme.bold(" Select file to open")), 0, 0));
+
+				// Build select items with colored operations
+				const items: SelectItem[] = files.map((f) => {
+					const ops: string[] = [];
+					if (f.operations.has("read")) ops.push(theme.fg("muted", "R"));
+					if (f.operations.has("write")) ops.push(theme.fg("success", "W"));
+					if (f.operations.has("edit")) ops.push(theme.fg("warning", "E"));
+					const opsLabel = ops.join("");
+					return {
+						value: f,
+						label: `${opsLabel} ${f.path}`,
+					};
+				});
+
+				const visibleRows = Math.min(files.length, 15);
+				let currentIndex = 0;
+
+				const selectList = new SelectList(items, visibleRows, {
+					selectedPrefix: (t) => theme.fg("accent", t),
+					selectedText: (t) => t, // Keep existing colors
+					description: (t) => theme.fg("muted", t),
+					scrollInfo: (t) => theme.fg("dim", t),
+					noMatch: (t) => theme.fg("warning", t),
+				});
+				selectList.onSelect = (item) => {
+					void openSelected(item.value as FileEntry);
+				};
+				selectList.onCancel = () => done();
+				selectList.onSelectionChange = (item) => {
+					currentIndex = items.indexOf(item);
+				};
+				container.addChild(selectList);
+
+				// Help text
+				container.addChild(
+					new Text(theme.fg("dim", " ↑↓ navigate • ←→ page • enter open • esc close"), 0, 0),
+				);
+
+				// Bottom border
+				container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
+
+				return {
+					render: (w) => container.render(w),
+					invalidate: () => container.invalidate(),
+					handleInput: (data) => {
+						// Add paging with left/right
+						if (matchesKey(data, Key.left)) {
+							// Page up - clamp to 0
+							currentIndex = Math.max(0, currentIndex - visibleRows);
+							selectList.setSelectedIndex(currentIndex);
+						} else if (matchesKey(data, Key.right)) {
+							// Page down - clamp to last
+							currentIndex = Math.min(items.length - 1, currentIndex + visibleRows);
+							selectList.setSelectedIndex(currentIndex);
+						} else {
+							selectList.handleInput(data);
+						}
+						tui.requestRender();
+					},
+				};
+			});
+		},
+	});
+}