1 files changed, 89 insertions, 0 deletions
diff --git a/src/domains/headers.ts b/src/domains/headers.ts
new file mode 100644
index 0000000..035c084
--- /dev/null
+++ b/src/domains/headers.ts
@@ -0,0 +1,89 @@
+import { Type } from "typebox";
+import type { BrowserClient } from "../client";
+import { type Result, err, ok } from "../util/result";
+import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
+import { cdpCall } from "./cdp-call";
+
+const HeaderValue = Type.String({
+  maxLength: 8192,
+  pattern: "^[^\\r\\n]*$",
+});
+
+const SetHeadersArgs = Type.Object({
+  headers: Type.Record(Type.String(), HeaderValue, {
+    minProperties: 1,
+    maxProperties: 64,
+    description: "Extra HTTP request headers for the current owned tab. Names must be valid HTTP tokens.",
+  }),
+});
+
+const HEADER_NAME = /^[!#$%&'*+\-.^_`|~0-9A-Za-z]+$/;
+
+const currentOwnedTarget = (
+  client: BrowserClient,
+): Result<{ readonly targetId: string }, ToolErr> => {
+  const current = client.current();
+  if (current === undefined || current === null) {
+    return err({ kind: "invalid_state", message: "No tab attached." });
+  }
+  if (!client.owns(current.targetId)) {
+    return err({
+      kind: "invalid_state",
+      message: `Current tab ${current.targetId} is not owned by this harness session.`,
+    });
+  }
+  return ok({ targetId: current.targetId });
+};
+
+export const setHeadersTool = defineBrowserTool({
+  name: "browser_set_headers",
+  label: "Browser Set Headers",
+  description:
+    "Set extra HTTP request headers on the current owned tab. Headers persist for subsequent document, subresource, fetch, and XHR requests until cleared or the tab closes.",
+  promptSnippet: "Set extra request headers on the current owned tab",
+  promptGuidelines: [
+    "If no tab is attached yet, call browser_new_tab without a URL first.",
+    "Call before navigation when a site requires routing or environment headers.",
+    "Call browser_clear_headers before switching tabs or navigating this tab to another origin.",
+    "Header values are never echoed in tool output.",
+  ],
+  parameters: SetHeadersArgs,
+  concurrency: "serialized",
+  async handler(args, { client }): Promise<Result<ToolOk, ToolErr>> {
+    const target = currentOwnedTarget(client);
+    if (!target.success) return target;
+    const invalidName = Object.keys(args.headers).find((name) => !HEADER_NAME.test(name));
+    if (invalidName !== undefined) {
+      return err({ kind: "invalid_state", message: `Invalid HTTP header name: ${JSON.stringify(invalidName)}` });
+    }
+    const result = await cdpCall(client, "Network.setExtraHTTPHeaders", { headers: args.headers });
+    if (!result.success) return result;
+    const headerNames = Object.keys(args.headers).sort();
+    return ok({
+      text: `Set ${headerNames.length} extra HTTP header(s) on tab ${target.data.targetId}: ${headerNames.join(", ")}. Values are hidden. Clear them before switching tabs or navigating to another origin.`,
+      details: { targetId: target.data.targetId, headerNames, count: headerNames.length },
+    });
+  },
+});
+
+export const clearHeadersTool = defineBrowserTool({
+  name: "browser_clear_headers",
+  label: "Browser Clear Headers",
+  description: "Clear all extra HTTP request headers previously set on the current owned tab.",
+  promptSnippet: "Clear extra request headers from the current owned tab",
+  promptGuidelines: [
+    "Call after finishing an environment-specific workflow, before switching tabs, or before navigating to another origin.",
+  ],
+  parameters: Type.Object({}),
+  concurrency: "serialized",
+  async handler(_args, { client }): Promise<Result<ToolOk, ToolErr>> {
+    const target = currentOwnedTarget(client);
+    if (!target.success) return target;
+    const result = await cdpCall(client, "Network.setExtraHTTPHeaders", { headers: {} });
+    if (!result.success) return result;
+    return ok({
+      text: `Cleared extra HTTP headers from tab ${target.data.targetId}.`,
+      details: { targetId: target.data.targetId },
+    });
+  },
+});