diff --git a/src/main.zig b/src/main.zig
index 4532c97..20ff2ce 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -6,6 +6,7 @@ const mobile_acceptance = @import("mobile_acceptance.zig");
 const panel = @import("panel.zig");
 const protocol = @import("protocol.zig");
 const replay = @import("replay.zig");
+const repo = @import("repo.zig");
 const session = @import("session.zig");
 const socket = @import("socket.zig");
 const symbol = @import("symbol.zig");
@@ -129,6 +130,7 @@ test {
     _ = panel;
     _ = protocol;
     _ = replay;
+    _ = repo;
     _ = session;
     _ = socket;
     _ = symbol;
diff --git a/src/repo.zig b/src/repo.zig
new file mode 100644
index 0000000..c82fbb0
--- /dev/null
+++ b/src/repo.zig
@@ -0,0 +1,181 @@
+const std = @import("std");
+
+// Minimal repo index for file picker/tree behavior.
+// req: repo/001, ui/002, testing/001, testing/002, testing/003, testing/004
+
+test {
+    _ = Index;
+}
+
+pub const Error = error{
+    InvalidPath,
+    InvalidPattern,
+    FileNotFound,
+};
+
+pub const Entry = struct {
+    path: []u8,
+    content: []u8,
+};
+
+pub const Index = struct {
+    allocator: std.mem.Allocator,
+    entries: std.ArrayList(Entry) = .empty,
+    ignore_patterns: std.ArrayList([]u8) = .empty,
+
+    pub fn init(allocator: std.mem.Allocator) Index {
+        return .{ .allocator = allocator };
+    }
+
+    pub fn deinit(self: *Index) void {
+        for (self.entries.items) |entry| {
+            self.allocator.free(entry.path);
+            self.allocator.free(entry.content);
+        }
+        self.entries.deinit(self.allocator);
+        for (self.ignore_patterns.items) |pattern| self.allocator.free(pattern);
+        self.ignore_patterns.deinit(self.allocator);
+        self.* = undefined;
+    }
+
+    pub fn clear(self: *Index) void {
+        for (self.entries.items) |entry| {
+            self.allocator.free(entry.path);
+            self.allocator.free(entry.content);
+        }
+        self.entries.clearRetainingCapacity();
+        for (self.ignore_patterns.items) |pattern| self.allocator.free(pattern);
+        self.ignore_patterns.clearRetainingCapacity();
+    }
+
+    pub fn addIgnorePattern(self: *Index, pattern: []const u8) !void {
+        try validatePattern(pattern);
+        try self.ignore_patterns.append(self.allocator, try self.allocator.dupe(u8, pattern));
+    }
+
+    pub fn addFile(self: *Index, path: []const u8, file_content: []const u8) !void {
+        try validatePath(path);
+        if (!std.unicode.utf8ValidateSlice(file_content)) return Error.InvalidPath;
+        try self.entries.append(self.allocator, .{
+            .path = try self.allocator.dupe(u8, path),
+            .content = try self.allocator.dupe(u8, file_content),
+        });
+    }
+
+    pub fn pickerItemsAlloc(self: *const Index, allocator: std.mem.Allocator, include_ignored: bool) ![][]const u8 {
+        var items = std.ArrayList([]const u8).empty;
+        errdefer items.deinit(allocator);
+        for (self.entries.items) |entry| {
+            if (!include_ignored and self.isIgnored(entry.path)) continue;
+            try items.append(allocator, entry.path);
+        }
+        return items.toOwnedSlice(allocator);
+    }
+
+    pub fn treeItemsAlloc(self: *const Index, allocator: std.mem.Allocator, include_ignored: bool) ![][]const u8 {
+        // Tree rows are path-shaped for now; rendering is still through the shared list primitive.
+        return self.pickerItemsAlloc(allocator, include_ignored);
+    }
+
+    pub fn content(self: *const Index, path: []const u8) ![]const u8 {
+        for (self.entries.items) |entry| {
+            if (std.mem.eql(u8, entry.path, path)) return entry.content;
+        }
+        return Error.FileNotFound;
+    }
+
+    pub fn isIgnored(self: *const Index, path: []const u8) bool {
+        for (self.ignore_patterns.items) |pattern| {
+            if (matchesPattern(pattern, path)) return true;
+        }
+        return false;
+    }
+};
+
+fn validatePath(path: []const u8) !void {
+    if (path.len == 0) return Error.InvalidPath;
+    if (!std.unicode.utf8ValidateSlice(path)) return Error.InvalidPath;
+    if (std.mem.startsWith(u8, path, "/") or std.mem.indexOf(u8, path, "..") != null) return Error.InvalidPath;
+    for (path) |byte| {
+        if (byte <= 0x20 or byte == '|') return Error.InvalidPath;
+    }
+}
+
+fn validatePattern(pattern: []const u8) !void {
+    if (pattern.len == 0) return Error.InvalidPattern;
+    if (!std.unicode.utf8ValidateSlice(pattern)) return Error.InvalidPattern;
+    for (pattern) |byte| {
+        if (byte <= 0x20 or byte == '|') return Error.InvalidPattern;
+    }
+}
+
+fn matchesPattern(pattern: []const u8, path: []const u8) bool {
+    if (std.mem.endsWith(u8, pattern, "/")) return std.mem.startsWith(u8, path, pattern);
+    if (std.mem.startsWith(u8, pattern, "*.")) return std.mem.endsWith(u8, path, pattern[1..]);
+    if (std.mem.indexOfScalar(u8, pattern, '/') != null) return std.mem.eql(u8, pattern, path) or std.mem.startsWith(u8, path, pattern);
+    var parts = std.mem.splitScalar(u8, path, '/');
+    while (parts.next()) |part| {
+        if (std.mem.eql(u8, part, pattern)) return true;
+    }
+    return false;
+}
+
+fn freeItems(allocator: std.mem.Allocator, items: [][]const u8) void {
+    allocator.free(items);
+}
+
+test "regular: picker respects gitignore by default and can include ignored" {
+    var repo = Index.init(std.testing.allocator);
+    defer repo.deinit();
+    try repo.addIgnorePattern("zig-out/");
+    try repo.addIgnorePattern("*.o");
+    try repo.addIgnorePattern("secret.txt");
+    try repo.addFile("src/main.zig", "pub fn main() void {}");
+    try repo.addFile("zig-out/bin/mim", "binary");
+    try repo.addFile("build.o", "object");
+    try repo.addFile("secret.txt", "hidden");
+
+    {
+        const items = try repo.pickerItemsAlloc(std.testing.allocator, false);
+        defer freeItems(std.testing.allocator, items);
+        try std.testing.expectEqual(@as(usize, 1), items.len);
+        try std.testing.expectEqualStrings("src/main.zig", items[0]);
+    }
+
+    {
+        const items = try repo.pickerItemsAlloc(std.testing.allocator, true);
+        defer freeItems(std.testing.allocator, items);
+        try std.testing.expectEqual(@as(usize, 4), items.len);
+    }
+}
+
+test "regular: tree rows use the same gitignore boundary as picker rows" {
+    var repo = Index.init(std.testing.allocator);
+    defer repo.deinit();
+    try repo.addIgnorePattern("tmp/");
+    try repo.addFile("src/main.zig", "main");
+    try repo.addFile("tmp/log.txt", "log");
+
+    const rows = try repo.treeItemsAlloc(std.testing.allocator, false);
+    defer freeItems(std.testing.allocator, rows);
+    try std.testing.expectEqual(@as(usize, 1), rows.len);
+    try std.testing.expectEqualStrings("src/main.zig", rows[0]);
+}
+
+test "regular: selected file content is retrievable" {
+    var repo = Index.init(std.testing.allocator);
+    defer repo.deinit();
+    try repo.addFile("src/main.zig", "const std = @import(\"std\");");
+
+    try std.testing.expectEqualStrings("const std = @import(\"std\");", try repo.content("src/main.zig"));
+}
+
+test "adversarial: invalid paths and patterns are rejected" {
+    var repo = Index.init(std.testing.allocator);
+    defer repo.deinit();
+
+    try std.testing.expectError(Error.InvalidPath, repo.addFile("../secret", "x"));
+    try std.testing.expectError(Error.InvalidPath, repo.addFile("two words", "x"));
+    try std.testing.expectError(Error.InvalidPattern, repo.addIgnorePattern("bad pattern"));
+    try std.testing.expectError(Error.FileNotFound, repo.content("missing.zig"));
+}
diff --git a/src/tui.zig b/src/tui.zig
index 579e65d..bc69b52 100644
--- a/src/tui.zig
+++ b/src/tui.zig
@@ -3,6 +3,7 @@ const input = @import("input.zig");
 const leader_mod = @import("leader.zig");
 const protocol = @import("protocol.zig");
 const replay = @import("replay.zig");
+const repo_mod = @import("repo.zig");
 const session_mod = @import("session.zig");
 const symbol_mod = @import("symbol.zig");
 
@@ -83,6 +84,7 @@ pub const Client = struct {
     allocator: std.mem.Allocator,
     session: session_mod.Session,
     leader: leader_mod.Leader,
+    repo: repo_mod.Index,
     viewport: Viewport,
     saved_bytes: ?[]u8 = null,
     message: ?[]const u8 = null,
@@ -94,12 +96,14 @@ pub const Client = struct {
             .allocator = allocator,
             .session = session_mod.Session.init(allocator),
             .leader = leader_mod.Leader.init(allocator),
+            .repo = repo_mod.Index.init(allocator),
             .viewport = viewport,
         };
     }
 
     pub fn deinit(self: *Client) void {
         if (self.saved_bytes) |bytes| self.allocator.free(bytes);
+        self.repo.deinit();
         self.leader.deinit();
         self.session.deinit();
         self.* = undefined;
@@ -114,6 +118,13 @@ pub const Client = struct {
 
         if (std.mem.startsWith(u8, line, "key ")) return self.handleTraceKey(line[4..]);
         if (std.mem.startsWith(u8, line, "type ")) return self.handleInput(line[5..]);
+        if (std.mem.startsWith(u8, line, "repo_gitignore ")) return self.repo.addIgnorePattern(line[15..]);
+        if (std.mem.startsWith(u8, line, "repo_file ")) return self.addRepoFile(line[10..]);
+        if (std.mem.eql(u8, line, "file_picker")) return self.openRepoList("files", false, false);
+        if (std.mem.eql(u8, line, "file_picker all")) return self.openRepoList("files", false, true);
+        if (std.mem.eql(u8, line, "file_tree")) return self.openRepoList("tree", true, false);
+        if (std.mem.eql(u8, line, "file_tree all")) return self.openRepoList("tree", true, true);
+        if (std.mem.eql(u8, line, "file_open_selected")) return self.openSelectedRepoFile();
         if (std.mem.startsWith(u8, line, "panel_open ")) return self.applyProtocolCommand(line);
         if (std.mem.startsWith(u8, line, "list_open ")) return self.applyProtocolCommand(line);
         if (std.mem.startsWith(u8, line, "list_filter ")) return self.applyProtocolCommand(line);
@@ -273,6 +284,29 @@ pub const Client = struct {
         return self.saved_bytes orelse Error.NothingSaved;
     }
 
+    fn addRepoFile(self: *Client, payload: []const u8) !void {
+        const separator = std.mem.indexOfScalar(u8, payload, '=') orelse return repo_mod.Error.InvalidPath;
+        try self.repo.addFile(payload[0..separator], payload[separator + 1 ..]);
+    }
+
+    fn openRepoList(self: *Client, title: []const u8, tree: bool, include_ignored: bool) !void {
+        const items = if (tree)
+            try self.repo.treeItemsAlloc(self.allocator, include_ignored)
+        else
+            try self.repo.pickerItemsAlloc(self.allocator, include_ignored);
+        defer self.allocator.free(items);
+        try self.session.openListPanel(title, items);
+        self.message = null;
+    }
+
+    fn openSelectedRepoFile(self: *Client) !void {
+        const selected = self.session.selectListPanel() catch return Error.ProtocolRejected;
+        const content = self.repo.content(selected) catch return Error.ProtocolRejected;
+        try self.session.openFixture(content);
+        try self.session.closePanel();
+        self.message = null;
+    }
+
     fn handleTraceKey(self: *Client, key_name: []const u8) !void {
         if (std.mem.eql(u8, key_name, "space")) return self.handleInput(" ");
         if (std.mem.eql(u8, key_name, "enter")) return self.handleInput("\r");
@@ -922,3 +956,79 @@ test "adversarial: render diagnostics name clipped panel sources" {
     try std.testing.expect(result.diagnostics.clipped_sources >= 1);
     try std.testing.expect(std.mem.indexOf(u8, result.warning, "clipped") != null);
 }
+
+test "regular: file picker respects gitignore by default and opens selected file" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 40, .height = 6 });
+    defer client.deinit();
+
+    try client.handleTraceLine("repo_gitignore zig-out/");
+    try client.handleTraceLine("repo_gitignore *.o");
+    try client.handleTraceLine("repo_file src/main.zig=pubfnmain");
+    try client.handleTraceLine("repo_file zig-out/bin/mim=binary");
+    try client.handleTraceLine("repo_file build.o=object");
+    try client.handleTraceLine("file_picker");
+    {
+        const frame = try client.render(std.testing.allocator);
+        defer std.testing.allocator.free(frame);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "src/main.zig") != null);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "zig-out") == null);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "build.o") == null);
+    }
+
+    try client.handleTraceLine("file_open_selected");
+    {
+        const frame = try client.render(std.testing.allocator);
+        defer std.testing.allocator.free(frame);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "pubfnmain") != null);
+    }
+}
+
+test "regular: file picker include ignored toggle exposes ignored files" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 40, .height = 6 });
+    defer client.deinit();
+
+    try client.handleTraceLine("repo_gitignore zig-out/");
+    try client.handleTraceLine("repo_file src/main.zig=main");
+    try client.handleTraceLine("repo_file zig-out/bin/mim=binary");
+    try client.handleTraceLine("file_picker all");
+    const frame = try client.render(std.testing.allocator);
+    defer std.testing.allocator.free(frame);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "src/main.zig") != null);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "zig-out/bin/mim") != null);
+}
+
+test "regular: file tree uses the same panel primitive and include ignored boundary" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 40, .height = 6 });
+    defer client.deinit();
+
+    try client.handleTraceLine("repo_gitignore tmp/");
+    try client.handleTraceLine("repo_file src/lib.zig=lib");
+    try client.handleTraceLine("repo_file tmp/log.txt=log");
+    try client.handleTraceLine("file_tree");
+    {
+        const frame = try client.render(std.testing.allocator);
+        defer std.testing.allocator.free(frame);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "src/lib.zig") != null);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "tmp/log") == null);
+    }
+
+    try client.handleTraceLine("panel_close");
+    try client.handleTraceLine("file_tree all");
+    {
+        const frame = try client.render(std.testing.allocator);
+        defer std.testing.allocator.free(frame);
+        try std.testing.expect(std.mem.indexOf(u8, frame, "tmp/log.txt") != null);
+    }
+}
+
+test "adversarial: invalid repo paths and missing selections fail without corrupting editor" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 32, .height = 5 });
+    defer client.deinit();
+
+    try client.handleTraceLine("open safe");
+    try std.testing.expectError(repo_mod.Error.InvalidPath, client.handleTraceLine("repo_file ../secret=x"));
+    try std.testing.expectError(Error.ProtocolRejected, client.handleTraceLine("file_open_selected"));
+    const frame = try client.render(std.testing.allocator);
+    defer std.testing.allocator.free(frame);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "safe") != null);
+}