refactor: attach and windowId become session methods

cdp/attach.ts and cdp/window.ts were a module each for a single
`map(await session.callBrowser(...))` one-liner that took the session as
its first argument — two files, two imports and two names for what the
session can expose itself. They are now session.attach(targetId) and
session.windowId(targetId).

session.ts also repeated `targetId ? tabs.get(targetId) : undefined`
eight times; that is now currentTab().

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

6 files changed, 31 insertions, 47 deletions

diff --git a/src/cdp/attach.ts b/src/cdp/attach.ts
deleted file mode 100644
index c1b101b..0000000
--- a/src/cdp/attach.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-import { map, type Result } from "../util/result";
-import type { CdpError } from "./errors";
-import type { CdpSession } from "./session";
-
-export const attachTo = async (
-  session: CdpSession,
-  targetId: string,
-): Promise<Result<string, CdpError>> =>
-  map(
-    await session.callBrowser("Target.attachToTarget", { targetId, flatten: true }),
-    (d) => d.sessionId,
-  );
diff --git a/src/cdp/session.ts b/src/cdp/session.ts
index de3fb28..0eb83fa 100644
--- a/src/cdp/session.ts
+++ b/src/cdp/session.ts
@@ -1,4 +1,4 @@
-import { type Result, ok } from "../util/result";
+import { map, type Result, ok } from "../util/result";
 import type { CdpError } from "./errors";
 import type { DialogInfo } from "./types";
 import type { OwnershipRegistry } from "./ownership";
@@ -7,8 +7,6 @@ import { type CdpMethod, type ParamsOf, type ResultOf, decodeResult } from "./co
 import { decodeEvent } from "./events";
 import { createNetworkBuffer, type DrainResult, type NetworkFilter } from "./network-buffer";
 import { createConsoleBuffer, type ConsoleDrainResult, type ConsoleFilter } from "./console-buffer";
-import { attachTo } from "./attach";
-import { getWindowId } from "./window";
 
 type TabSession = {
   sessionId: string;
@@ -26,6 +24,8 @@ const dialogType = (raw: string): DialogInfo["type"] =>
 
 export type CdpSession = {
   attachFirstPage(): Promise<Result<{ readonly targetId: string; readonly sessionId: string }, CdpError>>;
+  attach(targetId: string): Promise<Result<string, CdpError>>;
+  windowId(targetId: string): Promise<Result<number, CdpError>>;
   switchTo(targetId: string): Promise<Result<void, CdpError>>;
   current(): { readonly sessionId: string; readonly targetId: string } | null;
   setRefMap(refMap: Map<string, number>, refSig: Map<string, string>): void;
@@ -185,6 +185,14 @@ export const createCdpSession = (
     return decodeResult(method, raw.data);
   };
 
+  const attach = async (tid: string): Promise<Result<string, CdpError>> =>
+    map(await req("Target.attachToTarget", { targetId: tid, flatten: true }, null), (d) => d.sessionId);
+
+  const windowId = async (tid: string): Promise<Result<number, CdpError>> =>
+    map(await req("Browser.getWindowForTarget", { targetId: tid }, null), (d) => d.windowId);
+
+  const currentTab = (): TabSession | undefined => (targetId ? tabs.get(targetId) : undefined);
+
   const session: CdpSession = {
     async attachFirstPage() {
       await req("Target.setDiscoverTargets", { discover: true }, null);
@@ -203,7 +211,7 @@ export const createCdpSession = (
         if (anchorId === undefined) {
           ownership.setHarnessWindowId(undefined);
         } else {
-          const anchorWin = await getWindowId(session, anchorId);
+          const anchorWin = await windowId(anchorId);
           if (anchorWin.success) {
             const anchorWindowId = anchorWin.data;
             ownership.setHarnessWindowId(anchorWindowId);
@@ -211,7 +219,7 @@ export const createCdpSession = (
               allPages.map((p) =>
                 p.targetId === anchorId
                   ? Promise.resolve(anchorWin)
-                  : getWindowId(session, p.targetId),
+                  : windowId(p.targetId),
               ),
             );
             allPages.forEach((p, i) => {
@@ -254,12 +262,12 @@ export const createCdpSession = (
         if (ownership) {
           ownership.setHarnessWindow(created.data.targetId);
           ownership.add(created.data.targetId);
-          const win = await getWindowId(session, created.data.targetId);
+          const win = await windowId(created.data.targetId);
           if (win.success) ownership.setHarnessWindowId(win.data);
         }
       }
 
-      const attached = await attachTo(session, pickTargetId);
+      const attached = await attach(pickTargetId);
       if (!attached.success) return attached;
       const attachedSessionId = attached.data;
       sessionId = attachedSessionId;
@@ -281,7 +289,7 @@ export const createCdpSession = (
     async switchTo(tid) {
       const activated = await req("Target.activateTarget", { targetId: tid }, null);
       if (!activated.success) return activated;
-      const attached = await attachTo(session, tid);
+      const attached = await attach(tid);
       if (!attached.success) return attached;
       const attachedSessionId = attached.data;
       const existing = tabs.get(tid);
@@ -307,25 +315,27 @@ export const createCdpSession = (
       targetId = tid;
       return ok(undefined);
     },
+    attach,
+    windowId,
     current() {
       return sessionId && targetId ? { sessionId, targetId } : null;
     },
     setRefMap(refMap, refSig) {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       if (!tab) return;
       tab.refMap = refMap;
       tab.refSig = refSig;
     },
     resolveRef(ref) {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       return tab?.refMap.get(ref);
     },
     refSignatures() {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       return tab?.refSig ?? new Map();
     },
     refMappings() {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       return tab?.refMap ?? new Map();
     },
     call(method, params, opts) {
@@ -338,26 +348,26 @@ export const createCdpSession = (
       return req(method, params, null, opts);
     },
     takeDialog() {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       if (!tab) return null;
       const d = tab.dialog;
       tab.dialog = null;
       return d;
     },
     drainPageInfoInvalidations() {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       if (!tab) return false;
       const dirty = tab.pageInfoDirty;
       tab.pageInfoDirty = false;
       return dirty;
     },
     drainNetworkBuffer(filter) {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       if (!tab) return { records: [], total: 0, bufferOverflowed: false };
       return tab.networkBuffer.drain(filter);
     },
     drainConsoleBuffer(filter) {
-      const tab = targetId ? tabs.get(targetId) : undefined;
+      const tab = currentTab();
       if (!tab) return { records: [], total: 0, bufferOverflowed: false };
       return tab.consoleBuffer.drain(filter);
     },
diff --git a/src/cdp/target-factory.ts b/src/cdp/target-factory.ts
index 62c46f1..17d01be 100644
--- a/src/cdp/target-factory.ts
+++ b/src/cdp/target-factory.ts
@@ -3,9 +3,7 @@
 import { randomUUID } from "node:crypto";
 import type { BrowserClient } from "../client";
 import { type Result, err, ok } from "../util/result";
-import { attachTo } from "./attach";
 import { type CdpError, cdpError } from "./errors";
-import { getWindowId } from "./window";
 
 const SPAWN_DEADLINE_MS = 8_000;
 const SPAWN_POLL_MS = 100;
@@ -31,7 +29,7 @@ const listPageTargets = async (client: BrowserClient): Promise<Result<ReadonlyAr
 const sessionForTarget = async (client: BrowserClient, targetId: string): Promise<Result<string, CdpError>> => {
   const current = client.current();
   if (current?.targetId === targetId) return ok(current.sessionId);
-  return attachTo(client.session(), targetId);
+  return client.session().attach(targetId);
 };
 
 const spawnTabViaOpener = async (
@@ -130,7 +128,7 @@ const createDedicatedWindow = async (client: BrowserClient): Promise<Result<stri
   const ownership = client.ownership();
   ownership.setHarnessWindow(targetId);
   ownership.add(targetId);
-  const win = await getWindowId(client.session(), targetId);
+  const win = await client.session().windowId(targetId);
   if (win.success) ownership.setHarnessWindowId(win.data);
   return ok(targetId);
 };
diff --git a/src/cdp/window.ts b/src/cdp/window.ts
deleted file mode 100644
index b06f1ac..0000000
--- a/src/cdp/window.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-import { map, type Result } from "../util/result";
-import type { CdpError } from "./errors";
-import type { CdpSession } from "./session";
-
-export const getWindowId = async (
-  session: CdpSession,
-  targetId: string,
-): Promise<Result<number, CdpError>> =>
-  map(await session.callBrowser("Browser.getWindowForTarget", { targetId }), (d) => d.windowId);
diff --git a/src/domains/navigate.ts b/src/domains/navigate.ts
index 17e25a6..151a742 100644
--- a/src/domains/navigate.ts
+++ b/src/domains/navigate.ts
@@ -4,7 +4,6 @@ import { type Result, err, ok } from "../util/result";
 import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
 import { applyTruncation } from "../util/truncate";
 import { safeJs } from "../util/js-template";
-import { attachTo } from "../cdp/attach";
 import { ensureHarnessWindow, openHarnessTab } from "../cdp/target-factory";
 import { cdpCall, cdpCallBrowser, cdpCallOnTarget, evalJs } from "./cdp-call";
 
@@ -107,7 +106,7 @@ export const openUrlsTool = defineBrowserTool({
     const settled = await Promise.all(
       created.filter((t) => t.ok).map(async (tab): Promise<TabResult> => {
         try {
-          const attached = await attachTo(client.session(), tab.targetId);
+          const attached = await client.session().attach(tab.targetId);
           if (!attached.success) return { ...tab, ok: false, error: attached.error.message };
           const sid = attached.data;
           const enabled = await cdpCallOnTarget(client, "Page.enable", {}, sid);
diff --git a/src/profile/bind.ts b/src/profile/bind.ts
index ca745ca..95cffaa 100644
--- a/src/profile/bind.ts
+++ b/src/profile/bind.ts
@@ -1,8 +1,6 @@
 import type { BrowserClient } from "../client";
-import { attachTo } from "../cdp/attach";
 import type { ResultOf } from "../cdp/commands";
 import { type CdpError, cdpError } from "../cdp/errors";
-import { getWindowId } from "../cdp/window";
 import { type Result, err, ok } from "../util/result";
 import { detectRunningBrowser, resolveBrowserExecutable } from "./browser-process";
 import { openProfileWindow } from "./launch";
@@ -79,10 +77,10 @@ export const seedProfileWindow = async (
   const ownership = client.ownership();
   ownership.setHarnessWindow(seed.targetId);
   ownership.add(seed.targetId);
-  const win = await getWindowId(client.session(), seed.targetId);
+  const win = await client.session().windowId(seed.targetId);
   if (win.success) ownership.setHarnessWindowId(win.data);
 
-  const attached = await attachTo(client.session(), seed.targetId);
+  const attached = await client.session().attach(seed.targetId);
   if (attached.success) {
     await client.session().callOnTarget("Page.navigate", { url: "about:blank" }, attached.data);
   }