diff --git a/.github/workflows/zig.yml b/.github/workflows/zig.yml
index 4aebb9f..2cc0e46 100644
--- a/.github/workflows/zig.yml
+++ b/.github/workflows/zig.yml
@@ -10,69 +10,69 @@ jobs:
   c-build-gcc:
     name: C Build (GCC)
     runs-on: ubuntu-latest
-    
+
     steps:
     - uses: actions/checkout@v4
-    
+
     - name: Check GCC version
       run: gcc --version
-    
+
     - name: Build with GCC (C17 and C23)
       run: cd c && make clean && make gcc-builds
-    
+
     - name: Test GCC C17 executable
       run: cd c && echo -e "hi\npython\nexit" | timeout 5 ./chat-gcc-c17 || true
-    
+
     - name: Test GCC C23 executable
       run: cd c && echo -e "hi\npython\nexit" | timeout 5 ./chat-gcc-c23 || true
-    
+
     - name: Show binary sizes
       run: ls -lh c/chat-gcc-*
 
   c-build-clang:
     name: C Build (Clang)
     runs-on: ubuntu-latest
-    
+
     steps:
     - uses: actions/checkout@v4
-    
+
     - name: Install Clang
       run: sudo apt-get update && sudo apt-get install -y clang
-    
+
     - name: Check Clang version
       run: clang --version
-    
+
     - name: Build with Clang (C17 and C23)
       run: cd c && make clean && make clang-builds
-    
+
     - name: Test Clang C17 executable
       run: cd c && echo -e "hi\npython\nexit" | timeout 5 ./chat-clang-c17 || true
-    
+
     - name: Test Clang C23 executable
       run: cd c && echo -e "hi\npython\nexit" | timeout 5 ./chat-clang-c23 || true
-    
+
     - name: Show binary sizes
       run: ls -lh c/chat-clang-*
 
   zig-build-and-test:
     name: Zig Build & Test
     runs-on: ubuntu-latest
-    
+
     steps:
     - uses: actions/checkout@v4
-    
+
     - uses: goto-bus-stop/setup-zig@v2
       with:
-        version: 0.15.2
-    
+        version: 0.16.0
+
     - name: Build Zig chatbot
       run: cd zig && zig build
-    
+
     - name: Run Zig tests
       run: cd zig && zig build test
-    
+
     - name: Test Zig executable runs
       run: cd zig && echo -e "hi\npython\nexit" | timeout 5 ./zig-out/bin/chat || true
-    
+
     - name: Show binary size
       run: ls -lh zig/zig-out/bin/chat
diff --git a/test_inputs.txt b/test_inputs.txt
index 32c832f..c61cff7 100644
--- a/test_inputs.txt
+++ b/test_inputs.txt
@@ -1,4 +1,5 @@
 hi
+pure
 hey
 python
 light
diff --git a/zig/build.zig b/zig/build.zig
index 51157f2..f2ce570 100644
--- a/zig/build.zig
+++ b/zig/build.zig
@@ -34,4 +34,29 @@ pub fn build(b: *std.Build) void {
     const run_test = b.addRunArtifact(tests);
     const test_step = b.step("test", "Run tests");
     test_step.dependOn(&run_test.step);
+
+    // Fuzz tests
+    const fuzz_tests = b.addTest(.{
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/fuzz.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
+    });
+
+    const run_fuzz_test = b.addRunArtifact(fuzz_tests);
+    const fuzz_step = b.step("fuzz", "Run fuzz tests");
+    fuzz_step.dependOn(&run_fuzz_test.step);
+
+    // Fuzz executable for use with external fuzzers (afl-fuzz, etc.)
+    const fuzz_exe = b.addExecutable(.{
+        .name = "fuzz",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/fuzz.zig"),
+            .target = target,
+            .optimize = .ReleaseSafe, // keep safety checks for fuzzing
+        }),
+    });
+
+    b.installArtifact(fuzz_exe);
 }
diff --git a/zig/src/chatbot.zig b/zig/src/chatbot.zig
index 8197282..3da3f70 100644
--- a/zig/src/chatbot.zig
+++ b/zig/src/chatbot.zig
@@ -115,7 +115,7 @@ pub const HashTable = struct {
 };
 
 test "create_hashtable" {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
@@ -126,7 +126,7 @@ test "create_hashtable" {
 }
 
 test "set_and_get" {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
@@ -141,7 +141,7 @@ test "set_and_get" {
 }
 
 test "get_nonexistent_key" {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
@@ -154,7 +154,7 @@ test "get_nonexistent_key" {
 }
 
 test "update_existing_key" {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
@@ -170,7 +170,7 @@ test "update_existing_key" {
 }
 
 test "multiple_entries" {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
diff --git a/zig/src/fuzz.zig b/zig/src/fuzz.zig
new file mode 100644
index 0000000..cc631fd
--- /dev/null
+++ b/zig/src/fuzz.zig
@@ -0,0 +1,183 @@
+const std = @import("std");
+const chatbot = @import("chatbot.zig");
+const HashTable = chatbot.HashTable;
+
+/// Fuzz target: hammer the hash table with arbitrary key/value pairs
+/// Tests for memory safety, correct get-after-set semantics, and collision handling
+///
+/// To use with external fuzzer (afl-fuzz, honggfuzz, etc.), pipe input:
+///   echo -n "fuzz_data" | zig-out/bin/fuzz
+pub fn main(init: std.process.Init) !void {
+    // use a fixed-buffer allocator that will catch OOM without crashing
+    var buffer: [1024 * 1024]u8 = undefined;
+    var fba = std.heap.FixedBufferAllocator.init(&buffer);
+    const allocator = fba.allocator();
+
+    var ht = HashTable.create(allocator, 64) catch return;
+    defer ht.destroy();
+
+    // read stdin for fuzz input
+    const io = init.io;
+    const stdin_file = std.Io.File.stdin();
+    var input_buf: [1024 * 512]u8 = undefined;
+    var total_read: usize = 0;
+
+    // read until EOF using streaming reads
+    while (total_read < input_buf.len) {
+        const chunk = stdin_file.readStreaming(io, &.{input_buf[total_read..]}) catch break;
+        if (chunk == 0) break;
+        total_read += chunk;
+    }
+
+    fuzzHashTable(ht, allocator, input_buf[0..total_read]) catch return;
+}
+
+fn fuzzHashTable(ht: *HashTable, _: std.mem.Allocator, input: []const u8) !void {
+    var offset: usize = 0;
+
+    while (offset + 4 <= input.len) {
+        // read key length (1 byte, capped to 255)
+        const key_len = @min(input[offset], 127);
+        offset += 1;
+        if (offset + key_len > input.len) break;
+
+        const key = input[offset .. offset + key_len];
+        offset += key_len;
+
+        // read value length (1 byte, capped)
+        if (offset >= input.len) break;
+        const val_len = @min(input[offset], 127);
+        offset += 1;
+        if (offset + val_len > input.len) break;
+
+        const value = input[offset .. offset + val_len];
+        offset += val_len;
+
+        // read operation byte: 0 = set, 1 = get, 2 = set+get verify
+        if (offset >= input.len) break;
+        const op = input[offset] % 3;
+        offset += 1;
+
+        switch (op) {
+            0 => {
+                // set operation
+                ht.set(key, value) catch continue;
+            },
+            1 => {
+                // get operation - just exercise the code path
+                _ = ht.get(key);
+            },
+            2 => {
+                // set then verify get returns the same value
+                ht.set(key, value) catch continue;
+                const result = ht.get(key);
+                if (result) |r| {
+                    // value must match what we just set
+                    if (!std.mem.eql(u8, r, value)) {
+                        // this would be a bug!
+                        @panic("get returned wrong value after set");
+                    }
+                } else {
+                    @panic("get returned null immediately after set");
+                }
+            },
+            else => unreachable,
+        }
+    }
+
+    // stress test: verify all empty key edge case
+    ht.set("", "empty_key_value") catch {};
+    _ = ht.get("");
+
+    // stress test: same key multiple times to test update path
+    var i: usize = 0;
+    while (i < @min(input.len, 100)) : (i += 1) {
+        var val_buf: [8]u8 = undefined;
+        const val_slice = std.fmt.bufPrint(&val_buf, "{d}", .{i}) catch break;
+        ht.set("stress", val_slice) catch break;
+    }
+
+    // final verification
+    if (ht.get("stress")) |v| {
+        // value should be the last iteration number
+        _ = v;
+    }
+}
+
+test "fuzz_empty_input" {
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    var ht = try HashTable.create(allocator, 64);
+    defer ht.destroy();
+
+    try fuzzHashTable(ht, allocator, "");
+}
+
+test "fuzz_minimal_input" {
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    var ht = try HashTable.create(allocator, 64);
+    defer ht.destroy();
+
+    // format: key_len, key, val_len, val, op
+    const input = "\x03key\x05value\x02";
+    try fuzzHashTable(ht, allocator, input);
+
+    // verify it actually set
+    const result = ht.get("key");
+    try std.testing.expect(result != null);
+    try std.testing.expectEqualSlices(u8, result.?, "value");
+}
+
+test "fuzz_collision_stress" {
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    // small table to force collisions
+    var ht = try HashTable.create(allocator, 4);
+    defer ht.destroy();
+
+    // generate input that will cause hash collisions
+    var input_buf: [1024]u8 = undefined;
+    var offset: usize = 0;
+
+    var i: u8 = 0;
+    while (i < 50) : (i += 1) {
+        if (offset + 10 > input_buf.len) break;
+        input_buf[offset] = 4; // key len
+        offset += 1;
+        input_buf[offset] = 'k';
+        input_buf[offset + 1] = 'e';
+        input_buf[offset + 2] = 'y';
+        input_buf[offset + 3] = '0' + (i % 10);
+        offset += 4;
+        input_buf[offset] = 1; // val len
+        offset += 1;
+        input_buf[offset] = 'a' + i;
+        offset += 1;
+        input_buf[offset] = 2; // set+verify op
+        offset += 1;
+    }
+
+    try fuzzHashTable(ht, allocator, input_buf[0..offset]);
+}
+
+test "fuzz_special_chars" {
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    var ht = try HashTable.create(allocator, 64);
+    defer ht.destroy();
+
+    // keys/values with null bytes, high bytes, separators
+    const nasty_input = "\x05\x00\x01\x02\xff\xfe\x05\x00\x01\x02\xff\xfe\x02" ++
+        "\x06 .,\"\n\x00\x03abc\x02";
+
+    try fuzzHashTable(ht, allocator, nasty_input);
+}
diff --git a/zig/src/main.zig b/zig/src/main.zig
index f8d67df..1490c65 100644
--- a/zig/src/main.zig
+++ b/zig/src/main.zig
@@ -1,17 +1,15 @@
 const std = @import("std");
 const chatbot = @import("chatbot.zig");
 
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    defer _ = gpa.deinit();
-    const allocator = gpa.allocator();
+pub fn main(init: std.process.Init) !void {
+    const allocator = init.gpa;
+    const io = init.io;
 
-    // Zig 0.15 I/O: explicit buffer management
     var stdout_buf: [4096]u8 = undefined;
-    var stdout = std.fs.File.stdout().writer(&stdout_buf);
+    var stdout = std.Io.File.stdout().writerStreaming(io, &stdout_buf);
 
     var stdin_buf: [4096]u8 = undefined;
-    var stdin = std.fs.File.stdin().reader(&stdin_buf);
+    var stdin = std.Io.File.stdin().readerStreaming(io, &stdin_buf);
 
     try stdout.interface.print("$ Chatbot v1.0.0!\n", .{});
     try stdout.interface.flush();
@@ -32,12 +30,9 @@ pub fn main() !void {
         try stdout.interface.print("\n$ (user) ", .{});
         try stdout.interface.flush();
 
-        // Read line using Zig 0.15 delimiter API
-        // Use takeDelimiter which returns null on EOF with empty remaining
         const line = stdin.interface.takeDelimiter('\n') catch |err| {
             switch (err) {
                 error.StreamTooLong => {
-                    // Line too long, skip it
                     continue;
                 },
                 else => return err,
@@ -47,7 +42,7 @@ pub fn main() !void {
         if (line == null) break;
 
         const trimmed = std.mem.trim(u8, line.?, " \t\r\n");
-        if (trimmed.len == 0) continue; // Empty line, keep going
+        if (trimmed.len == 0) continue;
 
         var word_iter = std.mem.tokenizeAny(u8, trimmed, chatbot.SeparatorChars);