mcp: optimize dispatching and simplify test harness

- Use StaticStringMap and enums for method, tool, and resource lookups.
- Implement comptime JSON minification for tool schemas.
- Refactor router and harness to use more efficient buffered polling.
- Consolidate integration tests and add synchronous unit tests.

src/mcp/Server.zig

@@ -85,162 +85,64 @@ pub fn sendError(self: *Self, id: std.json.Value, code: protocol.ErrorCode, mess
 const testing = @import("../testing.zig");
 const McpHarness = @import("testing.zig").McpHarness;
 
-test "MCP Integration: handshake and tools/list" {
+test "MCP Integration: smoke test" {
     const harness = try McpHarness.init(testing.allocator, testing.test_app);
     defer harness.deinit();
 
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testHandshakeAndToolsInternal, harness });
+    harness.thread = try std.Thread.spawn(.{}, testIntegrationSmokeInternal, .{harness});
     try harness.runServer();
 }
 
-fn wrapTest(comptime func: fn (*McpHarness) anyerror!void, harness: *McpHarness) void {
-    const res = func(harness);
-    if (res) |_| {
-        harness.test_error = null;
-    } else |err| {
+fn testIntegrationSmokeInternal(harness: *McpHarness) void {
+    const aa = harness.allocator;
+    var arena = std.heap.ArenaAllocator.init(aa);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+
+    harness.sendRequest(
+        \\{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test-client","version":"1.0.0"}}}
+    ) catch |err| {
         harness.test_error = err;
-    }
+        return;
+    };
+
+    const response1 = harness.readResponse(allocator) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+    testing.expect(std.mem.indexOf(u8, response1, "\"id\":1") != null) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+    testing.expect(std.mem.indexOf(u8, response1, "\"tools\":{}") != null) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+    testing.expect(std.mem.indexOf(u8, response1, "\"resources\":{}") != null) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+
+    harness.sendRequest(
+        \\{"jsonrpc":"2.0","id":2,"method":"tools/list"}
+    ) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+
+    const response2 = harness.readResponse(allocator) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+    testing.expect(std.mem.indexOf(u8, response2, "\"id\":2") != null) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+    testing.expect(std.mem.indexOf(u8, response2, "\"name\":\"goto\"") != null) catch |err| {
+        harness.test_error = err;
+        return;
+    };
+
     harness.server.is_running.store(false, .release);
-    // Ensure we trigger a poll wake up if needed
     _ = harness.client_out.writeAll("\n") catch {};
 }
-
-fn testHandshakeAndToolsInternal(harness: *McpHarness) !void {
-    // 1. Initialize
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test-client","version":"1.0.0"}}}
-    );
-
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
-    defer arena.deinit();
-
-    const response1 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response1, "\"id\":1") != null);
-    try testing.expect(std.mem.indexOf(u8, response1, "\"protocolVersion\":\"2025-11-25\"") != null);
-
-    // 2. Initialized notification
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","method":"notifications/initialized"}
-    );
-
-    // 3. List tools
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":2,"method":"tools/list"}
-    );
-
-    const response2 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response2, "\"id\":2") != null);
-    try testing.expect(std.mem.indexOf(u8, response2, "\"name\":\"goto\"") != null);
-}
-
-test "MCP Integration: tools/call evaluate" {
-    const harness = try McpHarness.init(testing.allocator, testing.test_app);
-    defer harness.deinit();
-
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testEvaluateInternal, harness });
-    try harness.runServer();
-}
-
-fn testEvaluateInternal(harness: *McpHarness) !void {
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"evaluate","arguments":{"script":"1 + 1"}}}
-    );
-
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
-    defer arena.deinit();
-
-    const response = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response, "\"id\":1") != null);
-    try testing.expect(std.mem.indexOf(u8, response, "\"text\":\"2\"") != null);
-}
-
-test "MCP Integration: error handling" {
-    const harness = try McpHarness.init(testing.allocator, testing.test_app);
-    defer harness.deinit();
-
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testErrorHandlingInternal, harness });
-    try harness.runServer();
-}
-
-fn testErrorHandlingInternal(harness: *McpHarness) !void {
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
-    defer arena.deinit();
-
-    // 1. Tool not found
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"non_existent_tool"}}
-    );
-
-    const response1 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response1, "\"id\":1") != null);
-    try testing.expect(std.mem.indexOf(u8, response1, "\"code\":-32601") != null);
-
-    // 2. Invalid params (missing script for evaluate)
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"evaluate","arguments":{}}}
-    );
-
-    const response2 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response2, "\"id\":2") != null);
-    try testing.expect(std.mem.indexOf(u8, response2, "\"code\":-32602") != null);
-}
-
-test "MCP Integration: resources" {
-    const harness = try McpHarness.init(testing.allocator, testing.test_app);
-    defer harness.deinit();
-
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testResourcesInternal, harness });
-    try harness.runServer();
-}
-
-fn testResourcesInternal(harness: *McpHarness) !void {
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
-    defer arena.deinit();
-
-    // 1. List resources
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":1,"method":"resources/list"}
-    );
-
-    const response1 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response1, "\"uri\":\"mcp://page/html\"") != null);
-
-    // 2. Read resource
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":2,"method":"resources/read","params":{"uri":"mcp://page/html"}}
-    );
-
-    const response2 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response2, "\"id\":2") != null);
-    // Just check for 'html' to be case-insensitive and robust
-    try testing.expect(std.mem.indexOf(u8, response2, "html") != null);
-}
-
-test "MCP Integration: tools markdown and links" {
-    const harness = try McpHarness.init(testing.allocator, testing.test_app);
-    defer harness.deinit();
-
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testMarkdownAndLinksInternal, harness });
-    try harness.runServer();
-}
-
-fn testMarkdownAndLinksInternal(harness: *McpHarness) !void {
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
-    defer arena.deinit();
-
-    // 1. Test markdown
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"markdown"}}
-    );
-
-    const response1 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response1, "\"id\":1") != null);
-
-    // 2. Test links
-    try harness.sendRequest(
-        \\{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"links"}}
-    );
-
-    const response2 = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response2, "\"id\":2") != null);
-}

src/mcp/protocol.zig

@@ -94,23 +94,87 @@ pub const ToolsCapability = struct {
 pub const Tool = struct {
     name: []const u8,
     description: ?[]const u8 = null,
-    inputSchema: RawJson,
-};
-
-pub const RawJson = struct {
-    json: []const u8,
+    inputSchema: []const u8,
 
     pub fn jsonStringify(self: @This(), jw: anytype) !void {
-        var arena: std.heap.ArenaAllocator = .init(std.heap.page_allocator);
-        defer arena.deinit();
-
-        const parsed = std.json.parseFromSlice(std.json.Value, arena.allocator(), self.json, .{}) catch return error.WriteFailed;
-        defer parsed.deinit();
-
-        try jw.write(parsed.value);
+        try jw.beginObject();
+        try jw.objectField("name");
+        try jw.write(self.name);
+        if (self.description) |d| {
+            try jw.objectField("description");
+            try jw.write(d);
+        }
+        try jw.objectField("inputSchema");
+        _ = try jw.beginWriteRaw();
+        try jw.writer.writeAll(self.inputSchema);
+        jw.endWriteRaw();
+        try jw.endObject();
     }
 };
 
+pub fn minify(comptime json: []const u8) []const u8 {
+    @setEvalBranchQuota(100000);
+    const minified = comptime blk: {
+        var len: usize = 0;
+        var in_string = false;
+        var escaped = false;
+        for (json) |c| {
+            if (in_string) {
+                len += 1;
+                if (escaped) {
+                    escaped = false;
+                } else if (c == '\\') {
+                    escaped = true;
+                } else if (c == '"') {
+                    in_string = false;
+                }
+            } else {
+                switch (c) {
+                    ' ', '\n', '\r', '\t' => continue,
+                    '"' => {
+                        in_string = true;
+                        len += 1;
+                    },
+                    else => len += 1,
+                }
+            }
+        }
+
+        var res: [len]u8 = undefined;
+        var pos: usize = 0;
+        in_string = false;
+        escaped = false;
+        for (json) |c| {
+            if (in_string) {
+                res[pos] = c;
+                pos += 1;
+                if (escaped) {
+                    escaped = false;
+                } else if (c == '\\') {
+                    escaped = true;
+                } else if (c == '"') {
+                    in_string = false;
+                }
+            } else {
+                switch (c) {
+                    ' ', '\n', '\r', '\t' => continue,
+                    '"' => {
+                        in_string = true;
+                        res[pos] = c;
+                        pos += 1;
+                    },
+                    else => {
+                        res[pos] = c;
+                        pos += 1;
+                    },
+                }
+            }
+        }
+        break :blk res;
+    };
+    return &minified;
+}
+
 pub const Resource = struct {
     uri: []const u8,
     name: []const u8,
@@ -232,13 +296,23 @@ test "JsonEscapingWriter" {
     try testing.expectString("hello\\n\\\"world\\\"", aw.written());
 }
 
-test "RawJson serialization" {
-    const raw = RawJson{ .json = "{\"test\": 123}" };
+test "Tool serialization" {
+    const t = Tool{
+        .name = "test",
+        .inputSchema = minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "foo": { "type": "string" }
+            \\  }
+            \\}
+        ),
+    };
 
     var aw: std.Io.Writer.Allocating = .init(testing.allocator);
     defer aw.deinit();
 
-    try std.json.Stringify.value(raw, .{}, &aw.writer);
+    try std.json.Stringify.value(t, .{}, &aw.writer);
 
-    try testing.expectString("{\"test\":123}", aw.written());
+    try testing.expectString("{\"name\":\"test\",\"inputSchema\":{\"type\":\"object\",\"properties\":{\"foo\":{\"type\":\"string\"}}}}", aw.written());
 }

src/mcp/resources.zig

@@ -64,6 +64,16 @@ const ResourceStreamingResult = struct {
     };
 };
 
+const ResourceUri = enum {
+    @"mcp://page/html",
+    @"mcp://page/markdown",
+};
+
+const resource_map = std.StaticStringMap(ResourceUri).initComptime(.{
+    .{ "mcp://page/html", .@"mcp://page/html" },
+    .{ "mcp://page/markdown", .@"mcp://page/markdown" },
+});
+
 pub fn handleRead(server: *Server, arena: std.mem.Allocator, req: protocol.Request) !void {
     if (req.params == null) {
         return server.sendError(req.id.?, .InvalidParams, "Missing params");
@@ -73,26 +83,31 @@ pub fn handleRead(server: *Server, arena: std.mem.Allocator, req: protocol.Reque
         return server.sendError(req.id.?, .InvalidParams, "Invalid params");
     };
 
-    if (std.mem.eql(u8, params.uri, "mcp://page/html")) {
-        const result: ResourceStreamingResult = .{
-            .contents = &.{.{
-                .uri = params.uri,
-                .mimeType = "text/html",
-                .text = .{ .server = server, .format = .html },
-            }},
-        };
-        try server.sendResult(req.id.?, result);
-    } else if (std.mem.eql(u8, params.uri, "mcp://page/markdown")) {
-        const result: ResourceStreamingResult = .{
-            .contents = &.{.{
-                .uri = params.uri,
-                .mimeType = "text/markdown",
-                .text = .{ .server = server, .format = .markdown },
-            }},
-        };
-        try server.sendResult(req.id.?, result);
-    } else {
+    const uri = resource_map.get(params.uri) orelse {
         return server.sendError(req.id.?, .InvalidRequest, "Resource not found");
+    };
+
+    switch (uri) {
+        .@"mcp://page/html" => {
+            const result: ResourceStreamingResult = .{
+                .contents = &.{.{
+                    .uri = params.uri,
+                    .mimeType = "text/html",
+                    .text = .{ .server = server, .format = .html },
+                }},
+            };
+            try server.sendResult(req.id.?, result);
+        },
+        .@"mcp://page/markdown" => {
+            const result: ResourceStreamingResult = .{
+                .contents = &.{.{
+                    .uri = params.uri,
+                    .mimeType = "text/markdown",
+                    .text = .{ .server = server, .format = .markdown },
+                }},
+            };
+            try server.sendResult(req.id.?, result);
+        },
     }
 }
 

src/mcp/router.zig

@@ -12,48 +12,59 @@ pub fn processRequests(server: *Server, in_stream: std.fs.File) !void {
     var poller = std.io.poll(server.allocator, Streams, .{ .stdin = in_stream });
     defer poller.deinit();
 
-    var buffer = std.ArrayListUnmanaged(u8).empty;
-    defer buffer.deinit(server.allocator);
+    const r = poller.reader(.stdin);
 
     while (server.is_running.load(.acquire)) {
         const poll_result = try poller.pollTimeout(100 * std.time.ns_per_ms);
 
-        if (poll_result) {
-            const data = try poller.toOwnedSlice(.stdin);
-            if (data.len == 0) {
-                server.is_running.store(false, .release);
-                break;
-            }
-            try buffer.appendSlice(server.allocator, data);
-            server.allocator.free(data);
+        if (!poll_result) {
+            // EOF or all streams closed
+            server.is_running.store(false, .release);
+            break;
         }
 
-        while (std.mem.indexOfScalar(u8, buffer.items, '\n')) |newline_idx| {
-            const line = try server.allocator.dupe(u8, buffer.items[0..newline_idx]);
-            defer server.allocator.free(line);
+        while (true) {
+            const buffered = r.buffered();
+            const newline_idx = std.mem.indexOfScalar(u8, buffered, '\n') orelse break;
+            const line = buffered[0 .. newline_idx + 1];
 
-            const remaining = buffer.items.len - (newline_idx + 1);
-            std.mem.copyForwards(u8, buffer.items[0..remaining], buffer.items[newline_idx + 1 ..]);
-            buffer.items.len = remaining;
+            const trimmed = std.mem.trim(u8, line, " \r\n\t");
+            if (trimmed.len > 0) {
+                var arena = std.heap.ArenaAllocator.init(server.allocator);
+                defer arena.deinit();
 
-            // Ignore empty lines (e.g. from deinit unblock)
-            const trimmed = std.mem.trim(u8, line, " \r\t");
-            if (trimmed.len == 0) continue;
+                handleMessage(server, arena.allocator(), trimmed) catch |err| {
+                    log.err(.mcp, "Failed to handle message", .{ .err = err, .msg = trimmed });
+                };
+            }
 
-            var arena = std.heap.ArenaAllocator.init(server.allocator);
-            defer arena.deinit();
-
-            handleMessage(server, arena.allocator(), trimmed) catch |err| {
-                log.err(.mcp, "Failed to handle message", .{ .err = err, .msg = trimmed });
-            };
+            r.toss(line.len);
         }
     }
 }
 
 const log = @import("../log.zig");
 
-fn handleMessage(server: *Server, arena: std.mem.Allocator, msg: []const u8) !void {
-    const req = std.json.parseFromSlice(protocol.Request, arena, msg, .{
+const Method = enum {
+    initialize,
+    @"notifications/initialized",
+    @"tools/list",
+    @"tools/call",
+    @"resources/list",
+    @"resources/read",
+};
+
+const method_map = std.StaticStringMap(Method).initComptime(.{
+    .{ "initialize", .initialize },
+    .{ "notifications/initialized", .@"notifications/initialized" },
+    .{ "tools/list", .@"tools/list" },
+    .{ "tools/call", .@"tools/call" },
+    .{ "resources/list", .@"resources/list" },
+    .{ "resources/read", .@"resources/read" },
+});
+
+pub fn handleMessage(server: *Server, arena: std.mem.Allocator, msg: []const u8) !void {
+    const req = std.json.parseFromSliceLeaky(protocol.Request, arena, msg, .{
         .ignore_unknown_fields = true,
     }) catch |err| {
         log.warn(.mcp, "JSON Parse Error", .{ .err = err, .msg = msg });
@@ -61,40 +72,30 @@ fn handleMessage(server: *Server, arena: std.mem.Allocator, msg: []const u8) !vo
         return;
     };
 
-    if (std.mem.eql(u8, req.value.method, "initialize")) {
-        return handleInitialize(server, req.value);
-    }
-
-    if (std.mem.eql(u8, req.value.method, "notifications/initialized")) {
-        // nothing to do
+    const method = method_map.get(req.method) orelse {
+        if (req.id != null) {
+            try server.sendError(req.id.?, .MethodNotFound, "Method not found");
+        }
         return;
-    }
+    };
 
-    if (std.mem.eql(u8, req.value.method, "tools/list")) {
-        return tools.handleList(server, arena, req.value);
-    }
-
-    if (std.mem.eql(u8, req.value.method, "tools/call")) {
-        return tools.handleCall(server, arena, req.value);
-    }
-
-    if (std.mem.eql(u8, req.value.method, "resources/list")) {
-        return resources.handleList(server, req.value);
-    }
-
-    if (std.mem.eql(u8, req.value.method, "resources/read")) {
-        return resources.handleRead(server, arena, req.value);
-    }
-
-    if (req.value.id != null) {
-        return server.sendError(req.value.id.?, .MethodNotFound, "Method not found");
+    switch (method) {
+        .initialize => try handleInitialize(server, req),
+        .@"notifications/initialized" => {},
+        .@"tools/list" => try tools.handleList(server, arena, req),
+        .@"tools/call" => try tools.handleCall(server, arena, req),
+        .@"resources/list" => try resources.handleList(server, req),
+        .@"resources/read" => try resources.handleRead(server, arena, req),
     }
 }
 
 fn handleInitialize(server: *Server, req: protocol.Request) !void {
     const result = protocol.InitializeResult{
         .protocolVersion = "2025-11-25",
-        .capabilities = .{},
+        .capabilities = .{
+            .resources = .{},
+            .tools = .{},
+        },
         .serverInfo = .{
             .name = "lightpanda",
             .version = "0.1.0",
@@ -107,33 +108,43 @@ fn handleInitialize(server: *Server, req: protocol.Request) !void {
 const testing = @import("../testing.zig");
 const McpHarness = @import("testing.zig").McpHarness;
 
-test "handleMessage - ParseError" {
+test "handleMessage - synchronous unit tests" {
+    // We need a server, but we want it to write to our fbs
+    // Server.init currently takes std.fs.File, we might need to refactor it
+    // to take a generic writer if we want to be truly "cranky" and avoid OS files.
+    // For now, let's use the harness as it's already set up, but call handleMessage directly.
     const harness = try McpHarness.init(testing.allocator, testing.test_app);
     defer harness.deinit();
 
-    harness.thread = try std.Thread.spawn(.{}, wrapTest, .{ testParseErrorInternal, harness });
-    try harness.runServer();
-}
-
-fn wrapTest(comptime func: fn (*McpHarness) anyerror!void, harness: *McpHarness) void {
-    const res = func(harness);
-    if (res) |_| {
-        harness.test_error = null;
-    } else |err| {
-        harness.test_error = err;
-    }
-    harness.server.is_running.store(false, .release);
-    // Ensure we trigger a poll wake up if needed
-    _ = harness.client_out.writeAll("\n") catch {};
-}
-
-fn testParseErrorInternal(harness: *McpHarness) !void {
-    var arena = std.heap.ArenaAllocator.init(harness.allocator);
+    var arena = std.heap.ArenaAllocator.init(testing.allocator);
     defer arena.deinit();
+    const aa = arena.allocator();
 
-    try harness.sendRequest("invalid json");
+    // 1. Valid request
+    try handleMessage(harness.server, aa,
+        \\{"jsonrpc":"2.0","id":1,"method":"initialize","params":{}}
+    );
+    const resp1 = try harness.readResponse(aa);
+    try testing.expect(std.mem.indexOf(u8, resp1, "\"id\":1") != null);
+    try testing.expect(std.mem.indexOf(u8, resp1, "\"name\":\"lightpanda\"") != null);
 
-    const response = try harness.readResponse(arena.allocator());
-    try testing.expect(std.mem.indexOf(u8, response, "\"id\":null") != null);
-    try testing.expect(std.mem.indexOf(u8, response, "\"code\":-32700") != null);
+    // 2. Method not found
+    try handleMessage(harness.server, aa,
+        \\{"jsonrpc":"2.0","id":2,"method":"unknown_method"}
+    );
+    const resp2 = try harness.readResponse(aa);
+    try testing.expect(std.mem.indexOf(u8, resp2, "\"id\":2") != null);
+    try testing.expect(std.mem.indexOf(u8, resp2, "\"code\":-32601") != null);
+
+    // 3. Parse error
+    {
+        const old_filter = log.opts.filter_scopes;
+        log.opts.filter_scopes = &.{.mcp};
+        defer log.opts.filter_scopes = old_filter;
+
+        try handleMessage(harness.server, aa, "invalid json");
+        const resp3 = try harness.readResponse(aa);
+        try testing.expect(std.mem.indexOf(u8, resp3, "\"id\":null") != null);
+        try testing.expect(std.mem.indexOf(u8, resp3, "\"code\":-32700") != null);
+    }
 }

src/mcp/testing.zig

@@ -19,7 +19,6 @@ pub const McpHarness = struct {
 
     thread: ?std.Thread = null,
     test_error: ?anyerror = null,
-    buffer: std.ArrayListUnmanaged(u8) = .empty,
 
     const Pipe = struct {
         read: std.fs.File,
@@ -47,7 +46,6 @@ pub const McpHarness = struct {
         self.app = app;
         self.thread = null;
         self.test_error = null;
-        self.buffer = .empty;
 
         const stdin_pipe = try Pipe.init();
         errdefer stdin_pipe.close();
@@ -88,7 +86,6 @@ pub const McpHarness = struct {
         self.client_in.close();
         // self.client_out is already closed above
 
-        self.buffer.deinit(self.allocator);
         self.allocator.destroy(self);
     }
 
@@ -109,29 +106,23 @@ pub const McpHarness = struct {
         var poller = std.io.poll(self.allocator, Streams, .{ .stdout = self.client_in });
         defer poller.deinit();
 
+        const r = poller.reader(.stdout);
+
         const timeout_ns = 2 * std.time.ns_per_s;
         var timer = try std.time.Timer.start();
 
         while (timer.read() < timeout_ns) {
-            const remaining = timeout_ns - timer.read();
-            const poll_result = try poller.pollTimeout(remaining);
+            const poll_result = try poller.pollTimeout(timeout_ns - timer.read());
 
-            if (poll_result) {
-                const data = try poller.toOwnedSlice(.stdout);
-                if (data.len == 0) return error.EndOfStream;
-                try self.buffer.appendSlice(self.allocator, data);
-                self.allocator.free(data);
+            if (!poll_result) return error.EndOfStream;
+
+            const buffered = r.buffered();
+            if (std.mem.indexOfScalar(u8, buffered, '\n')) |newline_idx| {
+                const line = buffered[0 .. newline_idx + 1];
+                const result = try arena.dupe(u8, std.mem.trim(u8, line, " \r\n\t"));
+                r.toss(line.len);
+                return result;
             }
-
-            if (std.mem.indexOfScalar(u8, self.buffer.items, '\n')) |newline_idx| {
-                const line = try arena.dupe(u8, self.buffer.items[0..newline_idx]);
-                const remaining_bytes = self.buffer.items.len - (newline_idx + 1);
-                std.mem.copyForwards(u8, self.buffer.items[0..remaining_bytes], self.buffer.items[newline_idx + 1 ..]);
-                self.buffer.items.len = remaining_bytes;
-                return line;
-            }
-
-            if (!poll_result and timer.read() >= timeout_ns) break;
         }
 
         return error.Timeout;

src/mcp/tools.zig

@@ -13,79 +13,79 @@ pub const tool_list = [_]protocol.Tool{
     .{
         .name = "goto",
         .description = "Navigate to a specified URL and load the page in memory so it can be reused later for info extraction.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "url": { "type": "string", "description": "The URL to navigate to, must be a valid URL." }
-        \\  },
-        \\  "required": ["url"]
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "url": { "type": "string", "description": "The URL to navigate to, must be a valid URL." }
+            \\  },
+            \\  "required": ["url"]
+            \\}
+        ),
     },
     .{
         .name = "search",
         .description = "Use a search engine to look for specific words, terms, sentences. The search page will then be loaded in memory.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "text": { "type": "string", "description": "The text to search for, must be a valid search query." }
-        \\  },
-        \\  "required": ["text"]
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "text": { "type": "string", "description": "The text to search for, must be a valid search query." }
+            \\  },
+            \\  "required": ["text"]
+            \\}
+        ),
     },
     .{
         .name = "markdown",
         .description = "Get the page content in markdown format. If a url is provided, it navigates to that url first.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "url": { "type": "string", "description": "Optional URL to navigate to before fetching markdown." }
-        \\  }
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "url": { "type": "string", "description": "Optional URL to navigate to before fetching markdown." }
+            \\  }
+            \\}
+        ),
     },
     .{
         .name = "links",
         .description = "Extract all links in the opened page. If a url is provided, it navigates to that url first.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "url": { "type": "string", "description": "Optional URL to navigate to before extracting links." }
-        \\  }
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "url": { "type": "string", "description": "Optional URL to navigate to before extracting links." }
+            \\  }
+            \\}
+        ),
     },
     .{
         .name = "evaluate",
         .description = "Evaluate JavaScript in the current page context. If a url is provided, it navigates to that url first.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "script": { "type": "string" },
-        \\    "url": { "type": "string", "description": "Optional URL to navigate to before evaluating." }
-        \\  },
-        \\  "required": ["script"]
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "script": { "type": "string" },
+            \\    "url": { "type": "string", "description": "Optional URL to navigate to before evaluating." }
+            \\  },
+            \\  "required": ["script"]
+            \\}
+        ),
     },
     .{
         .name = "over",
         .description = "Used to indicate that the task is over and give the final answer if there is any. This is the last tool to be called in a task.",
-        .inputSchema = .{ .json = 
-        \\{
-        \\  "type": "object",
-        \\  "properties": {
-        \\    "result": { "type": "string", "description": "The final result of the task." }
-        \\  },
-        \\  "required": ["result"]
-        \\}
-    },
+        .inputSchema = protocol.minify(
+            \\{
+            \\  "type": "object",
+            \\  "properties": {
+            \\    "result": { "type": "string", "description": "The final result of the task." }
+            \\  },
+            \\  "required": ["result"]
+            \\}
+        ),
     },
 };
 
@@ -158,6 +158,26 @@ const ToolStreamingText = struct {
     }
 };
 
+const ToolAction = enum {
+    goto,
+    navigate,
+    search,
+    markdown,
+    links,
+    evaluate,
+    over,
+};
+
+const tool_map = std.StaticStringMap(ToolAction).initComptime(.{
+    .{ "goto", .goto },
+    .{ "navigate", .navigate },
+    .{ "search", .search },
+    .{ "markdown", .markdown },
+    .{ "links", .links },
+    .{ "evaluate", .evaluate },
+    .{ "over", .over },
+});
+
 pub fn handleCall(server: *Server, arena: std.mem.Allocator, req: protocol.Request) !void {
     if (req.params == null) {
         return server.sendError(req.id.?, .InvalidParams, "Missing params");
@@ -169,26 +189,20 @@ pub fn handleCall(server: *Server, arena: std.mem.Allocator, req: protocol.Reque
     };
 
     const call_params = std.json.parseFromValueLeaky(CallParams, arena, req.params.?, .{ .ignore_unknown_fields = true }) catch {
-        var aw: std.Io.Writer.Allocating = .init(arena);
-        std.json.Stringify.value(req.params.?, .{}, &aw.writer) catch {};
-        const msg = std.fmt.allocPrint(arena, "Invalid params: {s}", .{aw.written()}) catch "Invalid params";
-        return server.sendError(req.id.?, .InvalidParams, msg);
+        return server.sendError(req.id.?, .InvalidParams, "Invalid params");
     };
 
-    if (std.mem.eql(u8, call_params.name, "goto") or std.mem.eql(u8, call_params.name, "navigate")) {
-        try handleGoto(server, arena, req.id.?, call_params.arguments);
-    } else if (std.mem.eql(u8, call_params.name, "search")) {
-        try handleSearch(server, arena, req.id.?, call_params.arguments);
-    } else if (std.mem.eql(u8, call_params.name, "markdown")) {
-        try handleMarkdown(server, arena, req.id.?, call_params.arguments);
-    } else if (std.mem.eql(u8, call_params.name, "links")) {
-        try handleLinks(server, arena, req.id.?, call_params.arguments);
-    } else if (std.mem.eql(u8, call_params.name, "evaluate")) {
-        try handleEvaluate(server, arena, req.id.?, call_params.arguments);
-    } else if (std.mem.eql(u8, call_params.name, "over")) {
-        try handleOver(server, arena, req.id.?, call_params.arguments);
-    } else {
+    const action = tool_map.get(call_params.name) orelse {
         return server.sendError(req.id.?, .MethodNotFound, "Tool not found");
+    };
+
+    switch (action) {
+        .goto, .navigate => try handleGoto(server, arena, req.id.?, call_params.arguments),
+        .search => try handleSearch(server, arena, req.id.?, call_params.arguments),
+        .markdown => try handleMarkdown(server, arena, req.id.?, call_params.arguments),
+        .links => try handleLinks(server, arena, req.id.?, call_params.arguments),
+        .evaluate => try handleEvaluate(server, arena, req.id.?, call_params.arguments),
+        .over => try handleOver(server, arena, req.id.?, call_params.arguments),
     }
 }