diff --git a/src/main.zig b/src/main.zig
index c8561d4..597f351 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -25,6 +25,7 @@ const help_text =
     \\mim - mobile-first terminal code editor for SSH sessions
     \\
     \\Usage:
+    \\  mim [path]
     \\  mim [--help]
     \\  mim [--version]
     \\  mim context [task] [intent]
@@ -32,25 +33,25 @@ const help_text =
     \\  mim mimctl context <socket|-> [task] [intent]
     \\  mim --mimctl <socket|-> <request...>
     \\
-    \\This early build exposes the canonical smoke path, compact local context,
-    \\and a minimal local session-control client for trusted tools.
+    \\With no path, mim opens the current directory. Existing files open in the
+    \\editor; missing paths start a new buffer; directories open the file browser.
+    \\This early build also exposes compact local context and mimctl for trusted tools.
     \\
 ;
 
 const Command = union(enum) {
     help,
     version,
-    smoke,
-    unknown: []const u8,
+    open: []const u8,
 };
 
 fn parseArgs(args: []const []const u8) Command {
-    if (args.len <= 1) return .smoke;
+    if (args.len <= 1) return .{ .open = "." };
 
     const arg = args[1];
     if (std.mem.eql(u8, arg, "--help") or std.mem.eql(u8, arg, "-h")) return .help;
     if (std.mem.eql(u8, arg, "--version")) return .version;
-    return .{ .unknown = arg };
+    return .{ .open = arg };
 }
 
 fn versionText() []const u8 {
@@ -133,18 +134,200 @@ pub fn main(init: std.process.Init) !u8 {
     switch (command) {
         .help => try stdout.writeStreamingAll(init.io, help_text),
         .version => try stdout.writeStreamingAll(init.io, versionText()),
-        .smoke => try stdout.writeStreamingAll(init.io, help_text),
-        .unknown => |arg| {
-            try stderr.writeStreamingAll(init.io, "mim: unknown argument '");
-            try stderr.writeStreamingAll(init.io, arg);
-            try stderr.writeStreamingAll(init.io, "'\nTry 'mim --help'.\n");
-            return 64;
-        },
+        .open => |path| try openLocalEditor(allocator, init.io, stdout, stderr, path),
     }
 
     return 0;
 }
 
+fn openLocalEditor(
+    allocator: std.mem.Allocator,
+    io: std.Io,
+    stdout: std.Io.File,
+    stderr: std.Io.File,
+    path: []const u8,
+) !void {
+    var client = try tui.Client.init(allocator, .{ .width = 80, .height = 22 });
+    defer client.deinit();
+
+    const stat = std.Io.Dir.cwd().statFile(io, path, .{}) catch |err| switch (err) {
+        error.FileNotFound => null,
+        else => {
+            try stderr.writeStreamingAll(io, "mim: could not inspect path\n");
+            return err;
+        },
+    };
+
+    if (stat) |metadata| {
+        switch (metadata.kind) {
+            .directory => try openDirectoryPreview(allocator, io, &client, path),
+            .file => {
+                const bytes = std.Io.Dir.cwd().readFileAlloc(io, path, allocator, .limited(diagnostics.max_file_bytes)) catch |err| switch (err) {
+                    error.StreamTooLong => {
+                        try client.handleTraceLine("open diagnostic:file_too_large");
+                        return runLocalEditor(allocator, io, stdout, stderr, &client, path, false);
+                    },
+                    else => return err,
+                };
+                defer allocator.free(bytes);
+                const command = try std.fmt.allocPrint(allocator, "open {s}", .{bytes});
+                defer allocator.free(command);
+                try client.handleTraceLine(command);
+            },
+            else => try client.handleTraceLine("open diagnostic:unsupported_file"),
+        }
+    } else {
+        try client.handleTraceLine("open ");
+    }
+
+    try runLocalEditor(allocator, io, stdout, stderr, &client, path, stat != null and stat.?.kind == .directory);
+}
+
+fn openDirectoryPreview(allocator: std.mem.Allocator, io: std.Io, client: *tui.Client, path: []const u8) !void {
+    var dir = try std.Io.Dir.cwd().openDir(io, path, .{ .iterate = true });
+    defer dir.close(io);
+
+    var iterator = dir.iterate();
+    var count: usize = 0;
+    while (try iterator.next(io)) |entry| {
+        if (count >= 80) break;
+        if (entry.kind != .file and entry.kind != .directory) continue;
+        const suffix = if (entry.kind == .directory) "/" else "";
+        const command = try std.fmt.allocPrint(allocator, "repo_file {s}{s}=", .{ entry.name, suffix });
+        defer allocator.free(command);
+        client.handleTraceLine(command) catch {};
+        count += 1;
+    }
+    try client.handleTraceLine("file_picker");
+}
+
+fn runLocalEditor(
+    allocator: std.mem.Allocator,
+    io: std.Io,
+    stdout: std.Io.File,
+    stderr: std.Io.File,
+    client: *tui.Client,
+    path: []const u8,
+    is_dir: bool,
+) !void {
+    const stdin_file = std.Io.File.stdin();
+    const interactive = stdin_file.isTty(io) catch false;
+
+    var last_saved = try client.snapshotBytesAlloc(allocator);
+    defer allocator.free(last_saved);
+    var last_client_saved: ?[]u8 = null;
+    defer if (last_client_saved) |bytes| allocator.free(bytes);
+
+    if (!interactive) {
+        try renderLocalFrame(allocator, io, stdout, client, path, is_dir, false);
+        return;
+    }
+
+    var stdin_buffer: [4096]u8 = undefined;
+    var stdin_reader = stdin_file.readerStreaming(io, &stdin_buffer);
+    const stdin = &stdin_reader.interface;
+
+    while (true) {
+        try renderLocalFrame(allocator, io, stdout, client, path, is_dir, true);
+        const raw = try readEditorInputAlloc(allocator, stdin);
+        defer if (raw) |bytes| allocator.free(bytes);
+        if (raw == null) return;
+
+        client.handleInput(raw.?) catch |err| {
+            if (err == tui.Error.ClientQuit) return;
+            try stderr.writeStreamingAll(io, "mim: input failed: ");
+            try stderr.writeStreamingAll(io, @errorName(err));
+            try stderr.writeStreamingAll(io, "\n");
+            continue;
+        };
+
+        const after = try client.snapshotBytesAlloc(allocator);
+        defer allocator.free(after);
+        var dirty = !std.mem.eql(u8, after, last_saved);
+        if (client.saved()) |saved_bytes| {
+            const new_save_request = last_client_saved == null or !std.mem.eql(u8, saved_bytes, last_client_saved.?);
+            if (new_save_request) {
+                if (is_dir) {
+                    client.setStatusMessage("directory browser has nothing to save");
+                } else {
+                    try persistLocalSave(allocator, io, path, saved_bytes, &last_saved, &last_client_saved);
+                    dirty = false;
+                    client.setStatusMessage("saved");
+                }
+            }
+        } else |_| {}
+
+        if (client.requestedQuit()) {
+            if (dirty) {
+                client.clearQuit();
+                client.setStatusMessage("dirty buffer: Space s saves, quit blocked");
+                continue;
+            }
+            return;
+        }
+    }
+}
+
+fn persistLocalSave(
+    allocator: std.mem.Allocator,
+    io: std.Io,
+    path: []const u8,
+    bytes: []const u8,
+    last_saved: *[]u8,
+    last_client_saved: *?[]u8,
+) !void {
+    try std.Io.Dir.cwd().writeFile(io, .{ .sub_path = path, .data = bytes });
+    const saved_copy = try allocator.dupe(u8, bytes);
+    errdefer allocator.free(saved_copy);
+    const client_copy = try allocator.dupe(u8, bytes);
+    allocator.free(last_saved.*);
+    last_saved.* = saved_copy;
+    if (last_client_saved.*) |old| allocator.free(old);
+    last_client_saved.* = client_copy;
+}
+
+fn readEditorInputAlloc(allocator: std.mem.Allocator, stdin: *std.Io.Reader) !?[]u8 {
+    const first = stdin.takeByte() catch |err| switch (err) {
+        error.EndOfStream => return null,
+        else => return err,
+    };
+    var bytes = std.ArrayList(u8).empty;
+    errdefer bytes.deinit(allocator);
+    try bytes.append(allocator, first);
+
+    if (first == 0x1b) {
+        const second = stdin.takeByte() catch return try bytes.toOwnedSlice(allocator);
+        try bytes.append(allocator, second);
+        if (second == '[') {
+            const third = stdin.takeByte() catch return try bytes.toOwnedSlice(allocator);
+            try bytes.append(allocator, third);
+        }
+        return try bytes.toOwnedSlice(allocator);
+    }
+
+    const len = std.unicode.utf8ByteSequenceLength(first) catch 1;
+    var i: usize = 1;
+    while (i < len) : (i += 1) {
+        const next = stdin.takeByte() catch break;
+        try bytes.append(allocator, next);
+    }
+    return try bytes.toOwnedSlice(allocator);
+}
+
+fn renderLocalFrame(allocator: std.mem.Allocator, io: std.Io, stdout: std.Io.File, client: *tui.Client, path: []const u8, is_dir: bool, interactive: bool) !void {
+    const frame = try client.render(allocator);
+    defer allocator.free(frame);
+    if (interactive) try stdout.writeStreamingAll(io, "\x1b[H\x1b[2J");
+    try stdout.writeStreamingAll(io, frame);
+    try stdout.writeStreamingAll(io, "\n\n");
+    try stdout.writeStreamingAll(io, "mim opened: ");
+    try stdout.writeStreamingAll(io, path);
+    try stdout.writeStreamingAll(io, if (is_dir)
+        "\nDirectory browser. Space opens commands; o/Enter opens panel items where available; q quits when clean.\n"
+    else
+        "\nEditor. Type to insert; arrows move; Space shows commands; Space s saves; Space q quits when clean.\n");
+}
+
 fn printLocalContext(allocator: std.mem.Allocator, io: std.Io, args: *std.process.Args.Iterator, stdout: std.Io.File) !void {
     const task = args.next();
     const intent = args.next();
@@ -245,9 +428,9 @@ test {
     _ = tui;
 }
 
-test "regular: help text names the binary and smoke boundary" {
+test "regular: help text names the binary and open path" {
     try std.testing.expect(std.mem.indexOf(u8, help_text, "mim - mobile-first terminal code editor") != null);
-    try std.testing.expect(std.mem.indexOf(u8, help_text, "canonical smoke path") != null);
+    try std.testing.expect(std.mem.indexOf(u8, help_text, "mim [path]") != null);
     try std.testing.expect(std.mem.indexOf(u8, help_text, "mim context") != null);
     try std.testing.expect(std.mem.indexOf(u8, help_text, "mim profile") != null);
 }
@@ -264,20 +447,67 @@ test "regular: version output is stable enough for smoke checks" {
     try std.testing.expectEqualStrings("mim 0.1.0-dev\n", versionText());
 }
 
-test "adversarial: unknown arguments are rejected instead of ignored" {
-    const argv = [_][]const u8{ "mim", "--definitely-not-supported" };
+test "regular: no args opens current directory" {
+    const argv = [_][]const u8{"mim"};
     const parsed = parseArgs(&argv);
     switch (parsed) {
-        .unknown => |arg| try std.testing.expectEqualStrings("--definitely-not-supported", arg),
-        else => return error.ExpectedUnknownArgument,
+        .open => |path| try std.testing.expectEqualStrings(".", path),
+        else => return error.ExpectedOpenPath,
     }
 }
 
-test "adversarial: extra positional arguments are not treated as files yet" {
+test "regular: positional path opens file directory or new buffer" {
     const argv = [_][]const u8{ "mim", "some-file.zig" };
     const parsed = parseArgs(&argv);
     switch (parsed) {
-        .unknown => |arg| try std.testing.expectEqualStrings("some-file.zig", arg),
-        else => return error.ExpectedUnknownArgument,
+        .open => |path| try std.testing.expectEqualStrings("some-file.zig", path),
+        else => return error.ExpectedOpenPath,
     }
 }
+
+test "regular: local editor input reader preserves text utf8 and arrows" {
+    var ascii = std.Io.Reader.fixed("a");
+    const ascii_event = (try readEditorInputAlloc(std.testing.allocator, &ascii)).?;
+    defer std.testing.allocator.free(ascii_event);
+    try std.testing.expectEqualStrings("a", ascii_event);
+
+    var utf8 = std.Io.Reader.fixed("é");
+    const utf8_event = (try readEditorInputAlloc(std.testing.allocator, &utf8)).?;
+    defer std.testing.allocator.free(utf8_event);
+    try std.testing.expectEqualStrings("é", utf8_event);
+
+    var arrow = std.Io.Reader.fixed("\x1b[D");
+    const arrow_event = (try readEditorInputAlloc(std.testing.allocator, &arrow)).?;
+    defer std.testing.allocator.free(arrow_event);
+    try std.testing.expectEqualStrings("\x1b[D", arrow_event);
+}
+
+test "regular: local editor client exposes save and dirty quit guards" {
+    var client = try tui.Client.init(std.testing.allocator, .{ .width = 32, .height = 8 });
+    defer client.deinit();
+
+    try client.handleTraceLine("open ");
+    const initial = try client.snapshotBytesAlloc(std.testing.allocator);
+    defer std.testing.allocator.free(initial);
+    try std.testing.expectEqualStrings("", initial);
+
+    try client.handleInput("h");
+    try client.handleInput("e");
+    try client.handleInput("l");
+    try client.handleInput("l");
+    try client.handleInput("o");
+    const edited = try client.snapshotBytesAlloc(std.testing.allocator);
+    defer std.testing.allocator.free(edited);
+    try std.testing.expectEqualStrings("hello", edited);
+
+    try client.handleInput(" ");
+    try client.handleInput("s");
+    try std.testing.expectEqualStrings("hello", try client.saved());
+
+    try client.handleInput("!");
+    try client.handleInput(" ");
+    try client.handleInput("q");
+    try std.testing.expect(client.requestedQuit());
+    client.clearQuit();
+    try std.testing.expect(!client.requestedQuit());
+}
diff --git a/src/tui.zig b/src/tui.zig
index 4ddea77..7a0fbac 100644
--- a/src/tui.zig
+++ b/src/tui.zig
@@ -327,6 +327,23 @@ pub const Client = struct {
         return self.saved_bytes orelse Error.NothingSaved;
     }
 
+    pub fn snapshotBytesAlloc(self: *const Client, allocator: std.mem.Allocator) ![]u8 {
+        const snap = try self.session.snapshot();
+        return allocator.dupe(u8, snap.bytes);
+    }
+
+    pub fn requestedQuit(self: *const Client) bool {
+        return self.quit;
+    }
+
+    pub fn clearQuit(self: *Client) void {
+        self.quit = false;
+    }
+
+    pub fn setStatusMessage(self: *Client, message: []const u8) void {
+        self.message = message;
+    }
+
     fn addRepoFile(self: *Client, payload: []const u8) !void {
         const separator = std.mem.indexOfScalar(u8, payload, '=') orelse {
             self.message = "diagnostic:unsupported_file:invalid_repo_file_payload";