feat(tri-api): Direct Anthropic API agent — no claude CLI dependency (Issue #60)

Antigravity Agent · claude · Antigravity Agent · commit 9d7a55805fc7 · 2026-03-09T22:36:58.000+07:00
Self-contained agentic loop in src/tri-api/ (624 LOC, 3 files): - tool_executor.zig: 4 tools (read_file, write_file, bash, grep) via std - tool_protocol.zig: Anthropic Messages API JSON build/parse - main.zig: POST to api.anthropic.com/v1/messages, tool_use loop Zero cross-directory imports. Talks to Claude API directly from Zig. Closes #60 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
diff --git a/build.zig b/build.zig
@@ -2205,4 +2205,22 @@ pub fn build(b: *std.Build) void {
     // Also run as part of build step
     // b.getInstallStep().dependOn(&run_registry_export.step);
 
+    // ═══════════════════════════════════════════════════════════════════════════════
+    // TRI-API — Direct Anthropic API Agent (Issue #60)
+    // ═══════════════════════════════════════════════════════════════════════════════
+
+    const tri_api = b.addExecutable(.{
+        .name = "tri-api",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/tri-api/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
+    });
+    b.installArtifact(tri_api);
+    const run_tri_api = b.addRunArtifact(tri_api);
+    if (b.args) |args| run_tri_api.addArgs(args);
+    const tri_api_step = b.step("tri-api", "Run TRI-API — Direct Anthropic API Agent");
+    tri_api_step.dependOn(&run_tri_api.step);
+
 }
diff --git a/src/tri-api/main.zig b/src/tri-api/main.zig
@@ -0,0 +1,203 @@
+// main.zig — TRI-API: Direct Anthropic API agentic loop
+// No claude CLI dependency. Talks to api.anthropic.com/v1/messages directly.
+// Self-contained in src/tri-api/. Issue #60.
+const std = @import("std");
+const proto = @import("tool_protocol.zig");
+const executor = @import("tool_executor.zig");
+
+const api_url = "https://api.anthropic.com/v1/messages";
+const api_version = "2023-06-01";
+const max_turns = 20;
+const default_model = "claude-sonnet-4-20250514";
+
+pub fn main() !void {
+    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    // Read API key
+    const api_key = std.process.getEnvVarOwned(allocator, "ANTHROPIC_API_KEY") catch {
+        std.debug.print("error: ANTHROPIC_API_KEY not set\n", .{});
+        std.process.exit(1);
+    };
+    defer allocator.free(api_key);
+
+    // Parse CLI args: [--model <model>] <prompt...>
+    const args = try std.process.argsAlloc(allocator);
+    defer std.process.argsFree(allocator, args);
+
+    var model: []const u8 = default_model;
+    var prompt_start: usize = 1; // skip argv[0]
+
+    if (args.len > 2 and std.mem.eql(u8, args[1], "--model")) {
+        model = args[2];
+        prompt_start = 3;
+    }
+
+    if (prompt_start >= args.len) {
+        std.debug.print("usage: tri-api [--model <model>] <prompt>\n", .{});
+        std.process.exit(1);
+    }
+
+    // Join remaining args as prompt
+    const prompt = std.mem.join(allocator, " ", args[prompt_start..]) catch {
+        std.debug.print("error: out of memory\n", .{});
+        std.process.exit(1);
+    };
+    defer allocator.free(prompt);
+
+    std.debug.print("[tri-api] model={s} prompt={d} chars\n", .{ model, prompt.len });
+
+    // Build conversation: messages accumulate across turns
+    var messages = std.ArrayList(u8).empty;
+    defer messages.deinit(allocator);
+
+    // Initial user message
+    try messages.appendSlice(allocator, "[{\"role\":\"user\",\"content\":\"");
+    try proto.writeJsonEscaped(messages.writer(allocator), prompt);
+    try messages.appendSlice(allocator, "\"}");
+
+    var tool_exec = executor.ToolExecutor{ .allocator = allocator };
+    var total_input_tokens: u32 = 0;
+    var total_output_tokens: u32 = 0;
+
+    // Agentic loop
+    var turn: u32 = 0;
+    while (turn < max_turns) : (turn += 1) {
+        // Close messages array
+        var request_body = std.ArrayList(u8).empty;
+        defer request_body.deinit(allocator);
+
+        try request_body.appendSlice(allocator, "{\"model\":\"");
+        try request_body.appendSlice(allocator, model);
+        try request_body.appendSlice(allocator, "\",\"max_tokens\":8192,\"tools\":");
+        try proto.writeToolDefinitions(request_body.writer(allocator));
+        try request_body.appendSlice(allocator, ",\"messages\":");
+        try request_body.appendSlice(allocator, messages.items);
+        try request_body.appendSlice(allocator, "]}");
+
+        std.debug.print("[tri-api] turn {d}: sending {d} bytes...\n", .{ turn + 1, request_body.items.len });
+
+        // POST to Anthropic API
+        const response_body = httpPost(allocator, api_key, request_body.items) catch |err| {
+            std.debug.print("[tri-api] HTTP error: {s}\n", .{@errorName(err)});
+            break;
+        };
+        defer allocator.free(response_body);
+
+        // Parse response
+        var parsed = proto.parseResponse(allocator, response_body);
+        defer parsed.deinit(allocator);
+
+        total_input_tokens += parsed.input_tokens;
+        total_output_tokens += parsed.output_tokens;
+
+        // Process content blocks
+        var has_tool_use = false;
+
+        // Build assistant message for conversation history
+        try messages.appendSlice(allocator, ",{\"role\":\"assistant\",\"content\":");
+        try messages.appendSlice(allocator, extractContentArray(response_body) orelse "[]");
+        try messages.appendSlice(allocator, "}");
+
+        for (parsed.blocks.items) |block| {
+            switch (block) {
+                .text => |text| {
+                    const stdout_file = std.fs.File.stdout();
+                    var write_buf: [4096]u8 = undefined;
+                    var w = stdout_file.writer(&write_buf);
+                    std.Io.Writer.writeAll(&w.interface, text) catch {};
+                    std.Io.Writer.writeAll(&w.interface, "\n") catch {};
+                    w.end() catch {};
+                },
+                .tool_use => |tool| {
+                    has_tool_use = true;
+                    std.debug.print("[tri-api] tool: {s}({s})\n", .{ tool.name, tool.id });
+
+                    const tool_name = executor.ToolName.fromString(tool.name) orelse {
+                        std.debug.print("[tri-api] unknown tool: {s}\n", .{tool.name});
+                        continue;
+                    };
+
+                    const result = tool_exec.execute(tool_name, tool.input_json);
+
+                    // Append tool result to messages
+                    try messages.appendSlice(allocator, ",{\"role\":\"user\",\"content\":[");
+                    try proto.writeToolResult(messages.writer(allocator), tool.id, result.output, result.is_error);
+                    try messages.appendSlice(allocator, "]}");
+                },
+            }
+        }
+
+        // Check stop condition
+        if (std.mem.eql(u8, parsed.stop_reason, "end_turn") or !has_tool_use) {
+            std.debug.print("[tri-api] done: {s}\n", .{parsed.stop_reason});
+            break;
+        }
+    }
+
+    std.debug.print("[tri-api] {d} turns, {d} input + {d} output tokens\n", .{ turn + 1, total_input_tokens, total_output_tokens });
+}
+
+/// Extract the raw "content":[...] array from response body.
+fn extractContentArray(body: []const u8) ?[]const u8 {
+    const needle = "\"content\":[";
+    const idx = std.mem.indexOf(u8, body, needle) orelse return null;
+    const start = idx + "\"content\":".len;
+    // Find matching ]
+    var depth: u32 = 0;
+    var end = start;
+    var in_string = false;
+    while (end < body.len) : (end += 1) {
+        if (in_string) {
+            if (body[end] == '"' and (end == 0 or body[end - 1] != '\\')) in_string = false;
+            continue;
+        }
+        switch (body[end]) {
+            '"' => in_string = true,
+            '[' => depth += 1,
+            ']' => {
+                depth -= 1;
+                if (depth == 0) return body[start .. end + 1];
+            },
+            else => {},
+        }
+    }
+    return null;
+}
+
+/// POST JSON to Anthropic Messages API using Zig 0.15 std.http.Client.
+fn httpPost(allocator: std.mem.Allocator, api_key: []const u8, body: []const u8) ![]const u8 {
+    var client = std.http.Client{ .allocator = allocator };
+    defer client.deinit();
+
+    const uri = std.Uri.parse(api_url) catch unreachable;
+
+    var req = client.request(.POST, uri, .{
+        .extra_headers = &.{
+            .{ .name = "Content-Type", .value = "application/json" },
+            .{ .name = "x-api-key", .value = api_key },
+            .{ .name = "anthropic-version", .value = api_version },
+        },
+    }) catch return error.ConnectionFailed;
+    defer req.deinit();
+
+    req.transfer_encoding = .{ .content_length = body.len };
+    var body_writer = req.sendBodyUnflushed(&.{}) catch return error.ConnectionFailed;
+    body_writer.writer.writeAll(body) catch return error.ConnectionFailed;
+    body_writer.end() catch return error.ConnectionFailed;
+    if (req.connection) |conn| conn.flush() catch {};
+
+    var redirect_buf: [0]u8 = .{};
+    var response = req.receiveHead(&redirect_buf) catch return error.ConnectionFailed;
+
+    if (@intFromEnum(response.head.status) >= 400) {
+        std.debug.print("[tri-api] API status: {d}\n", .{@intFromEnum(response.head.status)});
+    }
+
+    var transfer_buf: [8192]u8 = undefined;
+    var reader = response.reader(&transfer_buf);
+    const resp_body = reader.allocRemaining(allocator, std.Io.Limit.limited(10 * 1024 * 1024)) catch return error.OutOfMemory;
+
+    return resp_body;
+}
diff --git a/src/tri-api/tool_executor.zig b/src/tri-api/tool_executor.zig
@@ -0,0 +1,135 @@
+// tool_executor.zig — Execute tools (read_file, write_file, bash, grep) via std
+// Self-contained: no cross-directory imports. Uses std.fs + std.process.Child only.
+const std = @import("std");
+const json = @import("tool_protocol.zig");
+
+pub const ToolName = enum {
+    read_file,
+    write_file,
+    bash,
+    grep,
+
+    pub fn fromString(name: []const u8) ?ToolName {
+        if (std.mem.eql(u8, name, "read_file")) return .read_file;
+        if (std.mem.eql(u8, name, "write_file")) return .write_file;
+        if (std.mem.eql(u8, name, "bash")) return .bash;
+        if (std.mem.eql(u8, name, "grep")) return .grep;
+        return null;
+    }
+};
+
+pub const ToolResult = struct {
+    output: []const u8,
+    is_error: bool,
+};
+
+pub const ToolExecutor = struct {
+    allocator: std.mem.Allocator,
+
+    pub fn execute(self: *ToolExecutor, name: ToolName, input_json: []const u8) ToolResult {
+        return switch (name) {
+            .read_file => self.readFile(input_json),
+            .write_file => self.writeFile(input_json),
+            .bash => self.runBash(input_json),
+            .grep => self.runGrep(input_json),
+        };
+    }
+
+    fn readFile(self: *ToolExecutor, input_json: []const u8) ToolResult {
+        const path = json.extractField(input_json, "path") orelse
+            return .{ .output = "error: missing 'path' field", .is_error = true };
+
+        const file = std.fs.cwd().openFile(path, .{}) catch |err|
+            return self.errResult("read_file: open failed: ", err);
+
+        defer file.close();
+
+        const content = file.readToEndAlloc(self.allocator, 512 * 1024) catch |err|
+            return self.errResult("read_file: read failed: ", err);
+
+        return .{ .output = content, .is_error = false };
+    }
+
+    fn writeFile(self: *ToolExecutor, input_json: []const u8) ToolResult {
+        const path = json.extractField(input_json, "path") orelse
+            return .{ .output = "error: missing 'path' field", .is_error = true };
+        const content = json.extractField(input_json, "content") orelse
+            return .{ .output = "error: missing 'content' field", .is_error = true };
+
+        // Unescape JSON string content (handle \n, \t, \\, \")
+        const unescaped = json.unescapeString(self.allocator, content) catch
+            return .{ .output = "error: unescape failed", .is_error = true };
+        defer self.allocator.free(unescaped);
+
+        const file = std.fs.cwd().createFile(path, .{}) catch |err|
+            return self.errResult("write_file: create failed: ", err);
+        defer file.close();
+
+        file.writeAll(unescaped) catch |err|
+            return self.errResult("write_file: write failed: ", err);
+
+        const msg = std.fmt.allocPrint(self.allocator, "wrote {d} bytes to {s}", .{ unescaped.len, path }) catch
+            return .{ .output = "wrote file", .is_error = false };
+        return .{ .output = msg, .is_error = false };
+    }
+
+    fn runBash(self: *ToolExecutor, input_json: []const u8) ToolResult {
+        const command = json.extractField(input_json, "command") orelse
+            return .{ .output = "error: missing 'command' field", .is_error = true };
+
+        const result = std.process.Child.run(.{
+            .allocator = self.allocator,
+            .argv = &.{ "sh", "-c", command },
+            .max_output_bytes = 512 * 1024,
+        }) catch |err| return self.errResult("bash: spawn failed: ", err);
+
+        defer self.allocator.free(result.stderr);
+
+        // If non-zero exit, combine stderr + stdout
+        if (result.term.Exited != 0) {
+            defer self.allocator.free(result.stdout);
+            const combined = std.fmt.allocPrint(
+                self.allocator,
+                "exit code {d}\n{s}{s}",
+                .{ result.term.Exited, result.stderr, result.stdout },
+            ) catch return .{ .output = "bash: error", .is_error = true };
+            return .{ .output = combined, .is_error = true };
+        }
+
+        return .{ .output = result.stdout, .is_error = false };
+    }
+
+    fn runGrep(self: *ToolExecutor, input_json: []const u8) ToolResult {
+        const pattern = json.extractField(input_json, "pattern") orelse
+            return .{ .output = "error: missing 'pattern' field", .is_error = true };
+        const path = json.extractField(input_json, "path") orelse ".";
+
+        const result = std.process.Child.run(.{
+            .allocator = self.allocator,
+            .argv = &.{ "grep", "-rn", pattern, path },
+            .max_output_bytes = 512 * 1024,
+        }) catch |err| return self.errResult("grep: spawn failed: ", err);
+
+        defer self.allocator.free(result.stderr);
+
+        // grep returns exit 1 for "no matches" — not an error
+        if (result.stdout.len == 0) {
+            self.allocator.free(result.stdout);
+            return .{ .output = "no matches found", .is_error = false };
+        }
+
+        return .{ .output = result.stdout, .is_error = false };
+    }
+
+    fn errResult(self: *ToolExecutor, prefix: []const u8, err: anyerror) ToolResult {
+        const msg = std.fmt.allocPrint(self.allocator, "{s}{s}", .{ prefix, @errorName(err) }) catch
+            return .{ .output = prefix, .is_error = true };
+        return .{ .output = msg, .is_error = true };
+    }
+};
+
+test "ToolName.fromString" {
+    try std.testing.expectEqual(ToolName.read_file, ToolName.fromString("read_file").?);
+    try std.testing.expectEqual(ToolName.bash, ToolName.fromString("bash").?);
+    try std.testing.expect(ToolName.fromString("unknown") == null);
+}
diff --git a/src/tri-api/tool_protocol.zig b/src/tri-api/tool_protocol.zig
