refactor: helpers live in helper modules, not in tool files

form.ts exported resolveAndCall and detailsOf to form-batch.ts,
snapshot.ts exported buildTree and collectInteractiveTargets to
ref-resolve.ts, and screenshot.ts exported captureWithCrosshair to
click.ts — so importing one tool pulled in another tool's whole module.

The shared halves move out: ax-tree.ts (the AX tree model, its
construction and the queries over it), element-call.ts (calling a
function on a resolved element, and the PageResult it returns),
screenshot-capture.ts (capture, resize, crosshair overlay). Each tool
file now holds its tools and its own presentation, nothing else.
NavOutcome stops being exported; nothing outside navigate.ts read it.

target.ts stays a module rather than folding into click.ts as planned:
it is already helper-only and has its own test suite, and moving a tested
pure function into a tool file is the thing this commit removes. Having
one consumer is not the defect.

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

10 files changed, 394 insertions, 375 deletions

diff --git a/src/domains/ax-tree.ts b/src/domains/ax-tree.ts
new file mode 100644
index 0000000..1329063
--- /dev/null
+++ b/src/domains/ax-tree.ts
@@ -0,0 +1,179 @@
+import type { AxNodeResult } from "../cdp/commands";
+import type { BrowserClient } from "../client";
+import type { Box } from "./box";
+import { cdpCall } from "./cdp-call";
+
+export type RawAxNode = AxNodeResult;
+type AxValue = NonNullable<RawAxNode["role"]>;
+
+export type SlimNode = {
+  role: string;
+  name?: string;
+  value?: string;
+  description?: string;
+  state?: string;
+  children: SlimNode[];
+  _backendId?: number;
+  ref?: string;
+  box?: Box;
+};
+
+export const INTERACTIVE_ROLES = new Set([
+  "button",
+  "link",
+  "textbox",
+  "checkbox",
+  "radio",
+  "combobox",
+  "menuitem",
+  "tab",
+  "switch",
+  "slider",
+  "searchbox",
+  "spinbutton",
+]);
+
+// The AX `value` is stale for freshly-typed or controlled inputs, so for these roles the live DOM property is read instead.
+export const VALUE_ROLES = new Set([
+  "textbox",
+  "searchbox",
+  "spinbutton",
+  "combobox",
+  "checkbox",
+  "radio",
+  "switch",
+  "slider",
+]);
+
+const stringOf = (v: AxValue | undefined): string | undefined => {
+  const x = v?.value;
+  if (typeof x === "string" && x !== "") return x;
+  if (typeof x === "number") return String(x);
+  return undefined;
+};
+
+const collectState = (props: RawAxNode["properties"]): string | undefined => {
+  if (!props || props.length === 0) return undefined;
+  const flags: string[] = [];
+  for (const p of props) {
+    const name = p.name;
+    if (!name) continue;
+    const raw = p.value?.value;
+    if (raw === true && (name === "focused" || name === "required" || name === "disabled" || name === "checked" || name === "expanded" || name === "selected" || name === "pressed" || name === "modal")) {
+      flags.push(name);
+    }
+    if (typeof raw === "number" && name === "level") flags.push(`level ${raw}`);
+  }
+  return flags.length > 0 ? flags.join(", ") : undefined;
+};
+
+export const buildTree = (
+  rawNodes: ReadonlyArray<RawAxNode>,
+  opts: { interestingOnly: boolean; maxNodes: number },
+): SlimNode[] => {
+  const byId = new Map<string, RawAxNode>();
+  for (const n of rawNodes) byId.set(n.nodeId, n);
+
+  const rootIds: string[] = [];
+  for (const n of rawNodes) {
+    if (!n.parentId || !byId.has(n.parentId)) rootIds.push(n.nodeId);
+  }
+
+  let budget = opts.maxNodes;
+
+  const slim = (node: RawAxNode): SlimNode | undefined => {
+    if (budget <= 0) return undefined;
+    if (opts.interestingOnly && node.ignored) {
+      // Chrome often ignores wrapper divs while their descendants remain meaningful, so recurse through an ignored node's children.
+      const out: SlimNode[] = [];
+      for (const cid of node.childIds ?? []) {
+        const child = byId.get(cid);
+        if (!child) continue;
+        const slimChild = slim(child);
+        if (slimChild) out.push(slimChild);
+      }
+      return out.length > 0 ? { role: "_hoist", children: out } : undefined;
+    }
+    budget--;
+    const role = stringOf(node.role) ?? "unknown";
+    const name = stringOf(node.name);
+    const value = stringOf(node.value);
+    const description = stringOf(node.description);
+    const state = collectState(node.properties);
+    const children: SlimNode[] = [];
+    for (const cid of node.childIds ?? []) {
+      const child = byId.get(cid);
+      if (!child) continue;
+      const slimChild = slim(child);
+      if (!slimChild) continue;
+      if (slimChild.role === "_hoist") children.push(...slimChild.children);
+      else children.push(slimChild);
+    }
+    const out: SlimNode = { role, children };
+    if (name !== undefined) out.name = name;
+    if (value !== undefined) out.value = value;
+    if (description !== undefined) out.description = description;
+    if (state !== undefined) out.state = state;
+    if (node.backendDOMNodeId !== undefined) out._backendId = node.backendDOMNodeId;
+    return out;
+  };
+
+  const result: SlimNode[] = [];
+  for (const rid of rootIds) {
+    const root = byId.get(rid);
+    if (!root) continue;
+    const s = slim(root);
+    if (!s) continue;
+    if (s.role === "_hoist") result.push(...s.children);
+    else result.push(s);
+  }
+  return result;
+};
+
+export const countNodes = (nodes: ReadonlyArray<SlimNode>): number => {
+  let n = 0;
+  for (const node of nodes) n += 1 + countNodes(node.children);
+  return n;
+};
+
+export const stripInternals = (nodes: ReadonlyArray<SlimNode>): SlimNode[] =>
+  nodes.map((n) => {
+    const { _backendId: _bid, ...rest } = n;
+    return { ...rest, children: stripInternals(n.children) };
+  });
+
+export const collectInteractiveTargets = (
+  nodes: ReadonlyArray<SlimNode>,
+): Array<{ node: SlimNode; backendId: number }> => {
+  const out: Array<{ node: SlimNode; backendId: number }> = [];
+  const walk = (ns: ReadonlyArray<SlimNode>): void => {
+    for (const n of ns) {
+      if (n._backendId !== undefined && INTERACTIVE_ROLES.has(n.role)) {
+        out.push({ node: n, backendId: n._backendId });
+      }
+      walk(n.children);
+    }
+  };
+  walk(nodes);
+  return out;
+};
+
+export const liveValue = async (client: BrowserClient, backendId: number): Promise<string | undefined> => {
+  const resolved = await cdpCall(client, "DOM.resolveNode", { backendNodeId: backendId });
+  if (!resolved.success) return undefined;
+  const objectId = resolved.data.object.objectId;
+  if (!objectId) return undefined;
+  const fn = `function () {
+    if (this.type === "checkbox" || this.type === "radio") return this.checked ? "checked" : "unchecked";
+    if (typeof this.value === "string") return this.value;
+    return null;
+  }`;
+  const r = await cdpCall(client, "Runtime.callFunctionOn", {
+    objectId,
+    functionDeclaration: fn,
+    returnByValue: true,
+  });
+  if (!r.success) return undefined;
+  const value = r.data.result.value;
+  return typeof value === "string" ? value : undefined;
+};
diff --git a/src/domains/click.ts b/src/domains/click.ts
index 41c3024..79bb5ee 100644
--- a/src/domains/click.ts
+++ b/src/domains/click.ts
@@ -6,7 +6,7 @@ import { type Result, ok } from "../util/result";
 import { debugClicksEnabled } from "../util/debug";
 import { defineBrowserTool, type ToolErr } from "../util/tool";
 import { cdpCall } from "./cdp-call";
-import { captureWithCrosshair } from "./screenshot";
+import { captureWithCrosshair } from "./screenshot-capture";
 import { interactiveDiff } from "./ref-resolve";
 import { resolveTarget } from "./target";
 
diff --git a/src/domains/element-call.ts b/src/domains/element-call.ts
new file mode 100644
index 0000000..0292e6f
--- /dev/null
+++ b/src/domains/element-call.ts
@@ -0,0 +1,117 @@
+import type { BrowserClient } from "../client";
+import { safeJs } from "../util/js-template";
+import { type Result, err, ok } from "../util/result";
+import type { ToolErr } from "../util/tool";
+import { cdpCall, evalJs } from "./cdp-call";
+import { resolveRefToObjectId } from "./ref-resolve";
+
+export type PageResult = {
+  readonly ok: boolean;
+  readonly reason?: string;
+  readonly kind?: string;
+  readonly value?: unknown;
+  readonly text?: string;
+  readonly checked?: boolean;
+  readonly changed?: boolean;
+  readonly tag?: string;
+  readonly options?: ReadonlyArray<{ value: string; text: string }>;
+};
+
+const isOption = (v: unknown): v is { readonly value: string; readonly text: string } =>
+  typeof v === "object" && v !== null
+  && "value" in v && typeof v.value === "string"
+  && "text" in v && typeof v.text === "string";
+
+export const isPageResult = (v: unknown): v is PageResult => {
+  if (typeof v !== "object" || v === null) return false;
+  if (!("ok" in v) || typeof v.ok !== "boolean") return false;
+  if ("reason" in v && typeof v.reason !== "string") return false;
+  if ("kind" in v && typeof v.kind !== "string") return false;
+  if ("text" in v && typeof v.text !== "string") return false;
+  if ("checked" in v && typeof v.checked !== "boolean") return false;
+  if ("changed" in v && typeof v.changed !== "boolean") return false;
+  if ("tag" in v && typeof v.tag !== "string") return false;
+  if ("options" in v && !(Array.isArray(v.options) && v.options.every(isOption))) return false;
+  return true;
+};
+
+export const runOnElement = async (
+  client: BrowserClient,
+  opts: {
+    ref?: string | undefined;
+    selector?: string | undefined;
+    fnBody: string;
+    arg: unknown;
+    notFound?: unknown;
+  },
+): Promise<Result<unknown, ToolErr>> => {
+  if (opts.ref !== undefined) {
+    const objectId = await resolveRefToObjectId(client, opts.ref);
+    if (!objectId.success) return objectId;
+    const r = await cdpCall(client, "Runtime.callFunctionOn", {
+      objectId: objectId.data,
+      functionDeclaration: `function (arg) { ${opts.fnBody} }`,
+      arguments: [{ value: opts.arg }],
+      returnByValue: true,
+    });
+    if (!r.success) return r;
+    if (r.data.exceptionDetails !== undefined) {
+      return err({
+        kind: "cdp_error",
+        message: `page function threw: ${r.data.exceptionDetails.text}`,
+        details: { ref: opts.ref },
+      });
+    }
+    return ok(r.data.result.value);
+  }
+  if (opts.selector === undefined) {
+    return err({ kind: "invalid_state", message: "Provide either `ref` or `selector`." });
+  }
+  // fnBody is harness-authored, not user input; only the selector and value are interpolated, and those go through safeJs.
+  const prelude = safeJs`
+    (() => {
+      const el = document.querySelector(${opts.selector});
+      if (!el) return ${opts.notFound ?? { status: "not_found" }};
+      const __arg = ${opts.arg};
+      return (function (arg) {`;
+  const expr = `${prelude} ${opts.fnBody} }).call(el, __arg); })()`;
+  const r = await evalJs(client, expr);
+  if (!r.success) return r;
+  return ok(r.data);
+};
+
+export const resolveAndCall = async (
+  client: BrowserClient,
+  ref: string,
+  functionDeclaration: string,
+  args: ReadonlyArray<unknown>,
+): Promise<Result<PageResult, ToolErr>> => {
+  const objectId = await resolveRefToObjectId(client, ref);
+  if (!objectId.success) return objectId;
+  const handle = objectId.data;
+  try {
+    const called = await cdpCall(client, "Runtime.callFunctionOn", {
+      objectId: handle,
+      functionDeclaration,
+      arguments: args.map((v) => ({ value: v })),
+      returnByValue: true,
+      awaitPromise: true,
+    });
+    if (!called.success) return err({ ...called.error, details: { ref } });
+    if (called.data.exceptionDetails !== undefined) {
+      return err({ kind: "cdp_error", message: `page function threw: ${JSON.stringify(called.data.exceptionDetails)}`, details: { ref } });
+    }
+    const value = called.data.result.value;
+    if (!isPageResult(value)) {
+      return err({ kind: "internal", message: "page function returned no result object", details: { ref } });
+    }
+    return ok(value);
+  } finally {
+    await cdpCall(client, "Runtime.releaseObject", { objectId: handle });
+  }
+};
+
+export const detailsOf = (ref: string, res: PageResult, extra?: Readonly<Record<string, unknown>>): Readonly<Record<string, unknown>> => {
+  const { ok: _ok, ...rest } = res;
+  return { ref, ...rest, ...(extra ?? {}) };
+};
diff --git a/src/domains/form-batch.ts b/src/domains/form-batch.ts
index 1d49cf6..567108b 100644
--- a/src/domains/form-batch.ts
+++ b/src/domains/form-batch.ts
@@ -2,7 +2,7 @@ import { Type } from "typebox";
 import { type Result, err, ok } from "../util/result";
 import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
 import { fillDeclaration } from "./fill-engine";
-import { detailsOf, resolveAndCall } from "./form";
+import { detailsOf, resolveAndCall } from "./element-call";
 
 const FILL_FN = fillDeclaration({ rejectSelect: false, focusFirst: true });
 
diff --git a/src/domains/form.ts b/src/domains/form.ts
index 8af43c3..577eb5d 100644
--- a/src/domains/form.ts
+++ b/src/domains/form.ts
@@ -1,11 +1,9 @@
 import { Type } from "typebox";
-import type { BrowserClient } from "../client";
-import { safeJs } from "../util/js-template";
 import { type Result, err, ok } from "../util/result";
 import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
-import { cdpCall, evalJs } from "./cdp-call";
+import { detailsOf, isPageResult, type PageResult, resolveAndCall, runOnElement } from "./element-call";
 import { fillBody } from "./fill-engine";
-import { interactiveDiff, resolveRefToObjectId } from "./ref-resolve";
+import { interactiveDiff } from "./ref-resolve";
 
 const FillArgs = Type.Object({
   ref: Type.Optional(
@@ -18,51 +16,6 @@ const FillArgs = Type.Object({
   value: Type.String({ description: "Value to set in the field" }),
 });
 
-const runOnElement = async (
-  client: BrowserClient,
-  opts: {
-    ref?: string | undefined;
-    selector?: string | undefined;
-    fnBody: string;
-    arg: unknown;
-    notFound?: unknown;
-  },
-): Promise<Result<unknown, ToolErr>> => {
-  if (opts.ref !== undefined) {
-    const objectId = await resolveRefToObjectId(client, opts.ref);
-    if (!objectId.success) return objectId;
-    const r = await cdpCall(client, "Runtime.callFunctionOn", {
-      objectId: objectId.data,
-      functionDeclaration: `function (arg) { ${opts.fnBody} }`,
-      arguments: [{ value: opts.arg }],
-      returnByValue: true,
-    });
-    if (!r.success) return r;
-    if (r.data.exceptionDetails !== undefined) {
-      return err({
-        kind: "cdp_error",
-        message: `page function threw: ${r.data.exceptionDetails.text}`,
-        details: { ref: opts.ref },
-      });
-    }
-    return ok(r.data.result.value);
-  }
-  if (opts.selector === undefined) {
-    return err({ kind: "invalid_state", message: "Provide either `ref` or `selector`." });
-  }
-  // fnBody is harness-authored, not user input; only the selector and value are interpolated, and those go through safeJs.
-  const prelude = safeJs`
-    (() => {
-      const el = document.querySelector(${opts.selector});
-      if (!el) return ${opts.notFound ?? { status: "not_found" }};
-      const __arg = ${opts.arg};
-      return (function (arg) {`;
-  const expr = `${prelude} ${opts.fnBody} }).call(el, __arg); })()`;
-  const r = await evalJs(client, expr);
-  if (!r.success) return r;
-  return ok(r.data);
-};
-
 const FILL_BODY = `const value = arg;\n${fillBody({ rejectSelect: true, focusFirst: false })}`;
 
 const NOT_FOUND: PageResult = { ok: false, reason: "not_found" };
@@ -281,72 +234,6 @@ export const selectOptionTool = defineBrowserTool({
   },
 });
 
-export type PageResult = {
-  readonly ok: boolean;
-  readonly reason?: string;
-  readonly kind?: string;
-  readonly value?: unknown;
-  readonly text?: string;
-  readonly checked?: boolean;
-  readonly changed?: boolean;
-  readonly tag?: string;
-  readonly options?: ReadonlyArray<{ value: string; text: string }>;
-};
-
-const isOption = (v: unknown): v is { readonly value: string; readonly text: string } =>
-  typeof v === "object" && v !== null
-  && "value" in v && typeof v.value === "string"
-  && "text" in v && typeof v.text === "string";
-
-const isPageResult = (v: unknown): v is PageResult => {
-  if (typeof v !== "object" || v === null) return false;
-  if (!("ok" in v) || typeof v.ok !== "boolean") return false;
-  if ("reason" in v && typeof v.reason !== "string") return false;
-  if ("kind" in v && typeof v.kind !== "string") return false;
-  if ("text" in v && typeof v.text !== "string") return false;
-  if ("checked" in v && typeof v.checked !== "boolean") return false;
-  if ("changed" in v && typeof v.changed !== "boolean") return false;
-  if ("tag" in v && typeof v.tag !== "string") return false;
-  if ("options" in v && !(Array.isArray(v.options) && v.options.every(isOption))) return false;
-  return true;
-};
-
-export const resolveAndCall = async (
-  client: BrowserClient,
-  ref: string,
-  functionDeclaration: string,
-  args: ReadonlyArray<unknown>,
-): Promise<Result<PageResult, ToolErr>> => {
-  const objectId = await resolveRefToObjectId(client, ref);
-  if (!objectId.success) return objectId;
-  const handle = objectId.data;
-  try {
-    const called = await cdpCall(client, "Runtime.callFunctionOn", {
-      objectId: handle,
-      functionDeclaration,
-      arguments: args.map((v) => ({ value: v })),
-      returnByValue: true,
-      awaitPromise: true,
-    });
-    if (!called.success) return err({ ...called.error, details: { ref } });
-    if (called.data.exceptionDetails !== undefined) {
-      return err({ kind: "cdp_error", message: `page function threw: ${JSON.stringify(called.data.exceptionDetails)}`, details: { ref } });
-    }
-    const value = called.data.result.value;
-    if (!isPageResult(value)) {
-      return err({ kind: "internal", message: "page function returned no result object", details: { ref } });
-    }
-    return ok(value);
-  } finally {
-    await cdpCall(client, "Runtime.releaseObject", { objectId: handle });
-  }
-};
-
-export const detailsOf = (ref: string, res: PageResult, extra?: Readonly<Record<string, unknown>>): Readonly<Record<string, unknown>> => {
-  const { ok: _ok, ...rest } = res;
-  return { ref, ...rest, ...(extra ?? {}) };
-};
-
 const CHECK_FN = `
 function(checked) {
   const el = this;
diff --git a/src/domains/navigate.ts b/src/domains/navigate.ts
index 8afea6f..17e25a6 100644
--- a/src/domains/navigate.ts
+++ b/src/domains/navigate.ts
@@ -12,7 +12,7 @@ const NavigateArgs = Type.Object({
   url: Type.String({ description: "Full URL to navigate to (e.g. https://github.com)" }),
 });
 
-export type NavOutcome =
+type NavOutcome =
   | { readonly kind: "in_place"; readonly targetId: string }
   | { readonly kind: "new_tab_created"; readonly targetId: string; readonly reason: "no_tabs" };
 
diff --git a/src/domains/ref-resolve.ts b/src/domains/ref-resolve.ts
index 0f509a0..9eb335e 100644
--- a/src/domains/ref-resolve.ts
+++ b/src/domains/ref-resolve.ts
@@ -3,7 +3,7 @@ import { type Result, err, ok } from "../util/result";
 import type { ToolErr } from "../util/tool";
 import { type Box, boxOf } from "./box";
 import { cdpCall } from "./cdp-call";
-import { buildTree, collectInteractiveTargets, type SlimNode } from "./snapshot";
+import { buildTree, collectInteractiveTargets, type SlimNode } from "./ax-tree";
 
 const staleErr = (ref: string): ToolErr => ({
   kind: "invalid_state",
diff --git a/src/domains/screenshot-capture.ts b/src/domains/screenshot-capture.ts
new file mode 100644
index 0000000..14bac06
--- /dev/null
+++ b/src/domains/screenshot-capture.ts
@@ -0,0 +1,80 @@
+import { rename, writeFile } from "node:fs/promises";
+import type { BrowserClient } from "../client";
+import { type Result, ok } from "../util/result";
+import type { ToolErr } from "../util/tool";
+import { screenshotPath } from "../util/paths";
+import { loadSharp } from "../util/sharp-shim";
+import { safeJs } from "../util/js-template";
+import { cdpCall, evalJs } from "./cdp-call";
+
+export type CaptureArgs = {
+  readonly fullPage?: boolean;
+  readonly format?: "png" | "jpeg";
+  readonly quality?: number;
+};
+
+export const captureBase = async (
+  client: BrowserClient,
+  args: CaptureArgs,
+): Promise<Result<{ readonly path: string; readonly format: "png" | "jpeg" }, ToolErr>> => {
+  const format = args.format ?? "png";
+  const quality = args.quality ?? 80;
+  const path = screenshotPath(client.namespace, format);
+  const r = await cdpCall(client, "Page.captureScreenshot", {
+    format,
+    captureBeyondViewport: args.fullPage ?? false,
+    ...(format === "jpeg" ? { quality } : {}),
+  });
+  if (!r.success) return r;
+  await writeFile(path, Buffer.from(r.data.data, "base64"));
+  return ok({ path, format });
+};
+
+export const resizeIfNeeded = async (
+  path: string,
+  maxDim: number,
+): Promise<{ readonly note: string }> => {
+  const load = await loadSharp();
+  if (load.kind === "missing") return { note: " (maxDim ignored: install sharp for auto-resize)" };
+  if (load.kind === "error") return { note: ` (maxDim ignored: sharp failed to load: ${load.message})` };
+  try {
+    const meta = await load.sharp(path).metadata();
+    const w = meta.width ?? 0;
+    const h = meta.height ?? 0;
+    if (Math.max(w, h) <= maxDim) return { note: "" };
+    const tmp = `${path}.resized`;
+    await load.sharp(path).resize(maxDim, maxDim, { fit: "inside" }).toFile(tmp);
+    await rename(tmp, path);
+    return { note: ` (resized to fit ${maxDim}px)` };
+  } catch (e) {
+    return { note: ` (maxDim ignored: sharp threw: ${e instanceof Error ? e.message : String(e)})` };
+  }
+};
+
+export const captureWithCrosshair = async (
+  client: BrowserClient,
+  args: { readonly x: number; readonly y: number; readonly format?: "png" | "jpeg"; readonly quality?: number },
+): Promise<Result<{ readonly path: string }, ToolErr>> => {
+  const cap = await captureBase(client, args);
+  if (!cap.success) return cap;
+  const load = await loadSharp();
+  if (load.kind !== "ok") return ok({ path: cap.data.path });
+  try {
+    const dprR = await evalJs(client, safeJs`window.devicePixelRatio`);
+    const dpr = dprR.success && typeof dprR.data === "number" ? dprR.data : 1;
+    const meta = await load.sharp(cap.data.path).metadata();
+    const w = meta.width ?? 0;
+    const h = meta.height ?? 0;
+    const px = Math.round(args.x * dpr);
+    const py = Math.round(args.y * dpr);
+    const r = Math.round(15 * dpr);
+    const stroke = Math.max(2, Math.round(3 * dpr));
+    const svg = `<svg width="${w}" height="${h}"><circle cx="${px}" cy="${py}" r="${r}" fill="none" stroke="red" stroke-width="${stroke}" opacity="0.8"/><line x1="${px - r - 5}" y1="${py}" x2="${px + r + 5}" y2="${py}" stroke="red" stroke-width="${Math.max(1, stroke - 1)}" opacity="0.8"/><line x1="${px}" y1="${py - r - 5}" x2="${px}" y2="${py + r + 5}" stroke="red" stroke-width="${Math.max(1, stroke - 1)}" opacity="0.8"/></svg>`;
+    const tmp = `${cap.data.path}.debug`;
+    await load.sharp(cap.data.path).composite([{ input: Buffer.from(svg), top: 0, left: 0 }]).toFile(tmp);
+    await rename(tmp, cap.data.path);
+    return ok({ path: cap.data.path });
+  } catch {
+    return ok({ path: cap.data.path });
+  }
+};
diff --git a/src/domains/screenshot.ts b/src/domains/screenshot.ts
index 4b5732d..9f2587c 100644
--- a/src/domains/screenshot.ts
+++ b/src/domains/screenshot.ts
@@ -1,15 +1,10 @@
 import { readFileSync } from "node:fs";
-import { writeFile, rename } from "node:fs/promises";
 import { Type } from "typebox";
 import { Image, type ImageTheme, Text, truncateToWidth, visibleWidth } from "@mariozechner/pi-tui";
-import type { BrowserClient } from "../client";
 import { type Result, ok } from "../util/result";
 import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
-import { screenshotPath } from "../util/paths";
-import { loadSharp } from "../util/sharp-shim";
 import { asRecord, asString } from "../util/guards";
-import { safeJs } from "../util/js-template";
-import { cdpCall, evalJs } from "./cdp-call";
+import { captureBase, resizeIfNeeded } from "./screenshot-capture";
 
 const ScreenshotArgs = Type.Object({
   fullPage: Type.Optional(Type.Boolean({ default: false, description: "Capture beyond viewport" })),
@@ -18,50 +13,6 @@ const ScreenshotArgs = Type.Object({
   maxDim: Type.Optional(Type.Integer({ minimum: 100, maximum: 8000, description: "If max(w,h) exceeds this, resize via sharp." })),
 });
 
-type CaptureArgs = {
-  readonly fullPage?: boolean;
-  readonly format?: "png" | "jpeg";
-  readonly quality?: number;
-};
-
-const captureBase = async (
-  client: BrowserClient,
-  args: CaptureArgs,
-): Promise<Result<{ readonly path: string; readonly format: "png" | "jpeg" }, ToolErr>> => {
-  const format = args.format ?? "png";
-  const quality = args.quality ?? 80;
-  const path = screenshotPath(client.namespace, format);
-  const r = await cdpCall(client, "Page.captureScreenshot", {
-    format,
-    captureBeyondViewport: args.fullPage ?? false,
-    ...(format === "jpeg" ? { quality } : {}),
-  });
-  if (!r.success) return r;
-  await writeFile(path, Buffer.from(r.data.data, "base64"));
-  return ok({ path, format });
-};
-
-const resizeIfNeeded = async (
-  path: string,
-  maxDim: number,
-): Promise<{ readonly note: string }> => {
-  const load = await loadSharp();
-  if (load.kind === "missing") return { note: " (maxDim ignored: install sharp for auto-resize)" };
-  if (load.kind === "error") return { note: ` (maxDim ignored: sharp failed to load: ${load.message})` };
-  try {
-    const meta = await load.sharp(path).metadata();
-    const w = meta.width ?? 0;
-    const h = meta.height ?? 0;
-    if (Math.max(w, h) <= maxDim) return { note: "" };
-    const tmp = `${path}.resized`;
-    await load.sharp(path).resize(maxDim, maxDim, { fit: "inside" }).toFile(tmp);
-    await rename(tmp, path);
-    return { note: ` (resized to fit ${maxDim}px)` };
-  } catch (e) {
-    return { note: ` (maxDim ignored: sharp threw: ${e instanceof Error ? e.message : String(e)})` };
-  }
-};
-
 export const screenshotTool = defineBrowserTool({
   name: "browser_screenshot",
   label: "Browser Screenshot",
@@ -123,31 +74,3 @@ export const screenshotTool = defineBrowserTool({
     }
   },
 });
-
-export const captureWithCrosshair = async (
-  client: BrowserClient,
-  args: { readonly x: number; readonly y: number; readonly format?: "png" | "jpeg"; readonly quality?: number },
-): Promise<Result<{ readonly path: string }, ToolErr>> => {
-  const cap = await captureBase(client, args);
-  if (!cap.success) return cap;
-  const load = await loadSharp();
-  if (load.kind !== "ok") return ok({ path: cap.data.path });
-  try {
-    const dprR = await evalJs(client, safeJs`window.devicePixelRatio`);
-    const dpr = dprR.success && typeof dprR.data === "number" ? dprR.data : 1;
-    const meta = await load.sharp(cap.data.path).metadata();
-    const w = meta.width ?? 0;
-    const h = meta.height ?? 0;
-    const px = Math.round(args.x * dpr);
-    const py = Math.round(args.y * dpr);
-    const r = Math.round(15 * dpr);
-    const stroke = Math.max(2, Math.round(3 * dpr));
-    const svg = `<svg width="${w}" height="${h}"><circle cx="${px}" cy="${py}" r="${r}" fill="none" stroke="red" stroke-width="${stroke}" opacity="0.8"/><line x1="${px - r - 5}" y1="${py}" x2="${px + r + 5}" y2="${py}" stroke="red" stroke-width="${Math.max(1, stroke - 1)}" opacity="0.8"/><line x1="${px}" y1="${py - r - 5}" x2="${px}" y2="${py + r + 5}" stroke="red" stroke-width="${Math.max(1, stroke - 1)}" opacity="0.8"/></svg>`;
-    const tmp = `${cap.data.path}.debug`;
-    await load.sharp(cap.data.path).composite([{ input: Buffer.from(svg), top: 0, left: 0 }]).toFile(tmp);
-    await rename(tmp, cap.data.path);
-    return ok({ path: cap.data.path });
-  } catch {
-    return ok({ path: cap.data.path });
-  }
-};
diff --git a/src/domains/snapshot.ts b/src/domains/snapshot.ts
index 848ebb1..86c5fe3 100644
--- a/src/domains/snapshot.ts
+++ b/src/domains/snapshot.ts
@@ -2,10 +2,18 @@ import { readFileSync, writeFileSync } from "node:fs";
 import { Type } from "typebox";
 import { Container, Image, type ImageTheme, Markdown, Text, truncateToWidth, visibleWidth } from "@mariozechner/pi-tui";
 import { getMarkdownTheme, keyHint } from "@mariozechner/pi-coding-agent";
-import type { BrowserClient } from "../client";
-import type { AxNodeResult } from "../cdp/commands";
-import { type Box, boxOf } from "./box";
+import { boxOf } from "./box";
 import { cdpCall } from "./cdp-call";
+import {
+  buildTree,
+  collectInteractiveTargets,
+  countNodes,
+  INTERACTIVE_ROLES,
+  liveValue,
+  type SlimNode,
+  stripInternals,
+  VALUE_ROLES,
+} from "./ax-tree";
 import { type Result, err, ok } from "../util/result";
 import { defineBrowserTool, type ToolErr, type ToolOk } from "../util/tool";
 import { applyTruncation } from "../util/truncate";
@@ -30,139 +38,6 @@ const SnapshotArgs = Type.Object({
   ),
 });
 
-export type RawAxNode = AxNodeResult;
-type AxValue = NonNullable<RawAxNode["role"]>;
-
-export type SlimNode = {
-  role: string;
-  name?: string;
-  value?: string;
-  description?: string;
-  state?: string;
-  children: SlimNode[];
-  _backendId?: number;
-  ref?: string;
-  box?: Box;
-};
-
-const INTERACTIVE_ROLES = new Set([
-  "button",
-  "link",
-  "textbox",
-  "checkbox",
-  "radio",
-  "combobox",
-  "menuitem",
-  "tab",
-  "switch",
-  "slider",
-  "searchbox",
-  "spinbutton",
-]);
-
-// The AX `value` is stale for freshly-typed or controlled inputs, so for these roles the live DOM property is read instead.
-const VALUE_ROLES = new Set([
-  "textbox",
-  "searchbox",
-  "spinbutton",
-  "combobox",
-  "checkbox",
-  "radio",
-  "switch",
-  "slider",
-]);
-
-const stringOf = (v: AxValue | undefined): string | undefined => {
-  const x = v?.value;
-  if (typeof x === "string" && x !== "") return x;
-  if (typeof x === "number") return String(x);
-  return undefined;
-};
-
-const collectState = (props: RawAxNode["properties"]): string | undefined => {
-  if (!props || props.length === 0) return undefined;
-  const flags: string[] = [];
-  for (const p of props) {
-    const name = p.name;
-    if (!name) continue;
-    const raw = p.value?.value;
-    if (raw === true && (name === "focused" || name === "required" || name === "disabled" || name === "checked" || name === "expanded" || name === "selected" || name === "pressed" || name === "modal")) {
-      flags.push(name);
-    }
-    if (typeof raw === "number" && name === "level") flags.push(`level ${raw}`);
-  }
-  return flags.length > 0 ? flags.join(", ") : undefined;
-};
-
-export const buildTree = (
-  rawNodes: ReadonlyArray<RawAxNode>,
-  opts: { interestingOnly: boolean; maxNodes: number },
-): SlimNode[] => {
-  const byId = new Map<string, RawAxNode>();
-  for (const n of rawNodes) byId.set(n.nodeId, n);
-
-  const rootIds: string[] = [];
-  for (const n of rawNodes) {
-    if (!n.parentId || !byId.has(n.parentId)) rootIds.push(n.nodeId);
-  }
-
-  let budget = opts.maxNodes;
-
-  const slim = (node: RawAxNode): SlimNode | undefined => {
-    if (budget <= 0) return undefined;
-    if (opts.interestingOnly && node.ignored) {
-      // Chrome often ignores wrapper divs while their descendants remain meaningful, so recurse through an ignored node's children.
-      const out: SlimNode[] = [];
-      for (const cid of node.childIds ?? []) {
-        const child = byId.get(cid);
-        if (!child) continue;
-        const slimChild = slim(child);
-        if (slimChild) out.push(slimChild);
-      }
-      return out.length > 0 ? { role: "_hoist", children: out } : undefined;
-    }
-    budget--;
-    const role = stringOf(node.role) ?? "unknown";
-    const name = stringOf(node.name);
-    const value = stringOf(node.value);
-    const description = stringOf(node.description);
-    const state = collectState(node.properties);
-    const children: SlimNode[] = [];
-    for (const cid of node.childIds ?? []) {
-      const child = byId.get(cid);
-      if (!child) continue;
-      const slimChild = slim(child);
-      if (!slimChild) continue;
-      if (slimChild.role === "_hoist") children.push(...slimChild.children);
-      else children.push(slimChild);
-    }
-    const out: SlimNode = { role, children };
-    if (name !== undefined) out.name = name;
-    if (value !== undefined) out.value = value;
-    if (description !== undefined) out.description = description;
-    if (state !== undefined) out.state = state;
-    if (node.backendDOMNodeId !== undefined) out._backendId = node.backendDOMNodeId;
-    return out;
-  };
-
-  const result: SlimNode[] = [];
-  for (const rid of rootIds) {
-    const root = byId.get(rid);
-    if (!root) continue;
-    const s = slim(root);
-    if (!s) continue;
-    if (s.role === "_hoist") result.push(...s.children);
-    else result.push(s);
-  }
-  return result;
-};
-
-const countNodes = (nodes: ReadonlyArray<SlimNode>): number => {
-  let n = 0;
-  for (const node of nodes) n += 1 + countNodes(node.children);
-  return n;
-};
-
 const summarize = (nodes: ReadonlyArray<SlimNode>): string => {
   const counts = new Map<string, number>();
   const walk = (ns: ReadonlyArray<SlimNode>): void => {
@@ -207,48 +82,6 @@ const renderOutline = (nodes: ReadonlyArray<SlimNode>): string => {
   return lines.join("\n");
 };
 
-const stripInternals = (nodes: ReadonlyArray<SlimNode>): SlimNode[] =>
-  nodes.map((n) => {
-    const { _backendId: _bid, ...rest } = n;
-    return { ...rest, children: stripInternals(n.children) };
-  });
-
-export const collectInteractiveTargets = (
-  nodes: ReadonlyArray<SlimNode>,
-): Array<{ node: SlimNode; backendId: number }> => {
-  const out: Array<{ node: SlimNode; backendId: number }> = [];
-  const walk = (ns: ReadonlyArray<SlimNode>): void => {
-    for (const n of ns) {
-      if (n._backendId !== undefined && INTERACTIVE_ROLES.has(n.role)) {
-        out.push({ node: n, backendId: n._backendId });
-      }
-      walk(n.children);
-    }
-  };
-  walk(nodes);
-  return out;
-};
-
-const liveValue = async (client: BrowserClient, backendId: number): Promise<string | undefined> => {
-  const resolved = await cdpCall(client, "DOM.resolveNode", { backendNodeId: backendId });
-  if (!resolved.success) return undefined;
-  const objectId = resolved.data.object.objectId;
-  if (!objectId) return undefined;
-  const fn = `function () {
-    if (this.type === "checkbox" || this.type === "radio") return this.checked ? "checked" : "unchecked";
-    if (typeof this.value === "string") return this.value;
-    return null;
-  }`;
-  const r = await cdpCall(client, "Runtime.callFunctionOn", {
-    objectId,
-    functionDeclaration: fn,
-    returnByValue: true,
-  });
-  if (!r.success) return undefined;
-  const value = r.data.result.value;
-  return typeof value === "string" ? value : undefined;
-};
-
 type SnapshotDetails = {
   nodeCount: number;
   truncated: boolean;