refactor: one door from a tool to the browser

Four routes coexisted: cdpCall, a raw client.session().call, a session
held in a local and called directly, and client.evaluateJs — and five
files mixed two or three of them. The CdpError-to-ToolErr mapping was
hand-copied at nine sites, plus a private copy in isolated-tab.ts.

domains/cdp-call.ts now owns all of it: cdpErrToToolErr, cdpCall,
cdpCallOnTarget, cdpCallBrowser, evalJs. Every other file under
src/domains goes through them, which also removes a pile of
`if (!r.success) return err({ kind: "cdp_error", ... })` boilerplate in
favour of returning the failed Result as-is.

Two scanner rules keep it that way, scoped to src/domains/ so the layer
that legitimately owns the session — cdp/ and client.ts — is unaffected.
Scoping is new to the rule model; without it the rules fired on the
transport itself.

One deliberate behaviour change: a CDP timeout now surfaces as
kind "timeout" rather than "cdp_error". isolated-tab.ts already did this
and the other 13 sites flattened it; the shared mapper uses the honest
label rather than preserving the mislabel.

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

1 files changed, 3 insertions, 2 deletions

diff --git a/src/domains/ref-resolve.ts b/src/domains/ref-resolve.ts
index ece308e..0f509a0 100644
--- a/src/domains/ref-resolve.ts
+++ b/src/domains/ref-resolve.ts
@@ -2,6 +2,7 @@ import type { BrowserClient } from "../client";
 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";
 
 const staleErr = (ref: string): ToolErr => ({
@@ -16,7 +17,7 @@ export const resolveRefToObjectId = async (
 ): Promise<Result<string, ToolErr>> => {
   const backendId = client.session().resolveRef(ref);
   if (backendId === undefined) return err(staleErr(ref));
-  const resolved = await client.session().call("DOM.resolveNode", { backendNodeId: backendId });
+  const resolved = await cdpCall(client, "DOM.resolveNode", { backendNodeId: backendId });
   if (!resolved.success) {
     return err(staleErr(ref));
   }
@@ -49,7 +50,7 @@ export const interactiveDiff = async (client: BrowserClient): Promise<string> =>
   const session = client.session();
   const prev = session.refSignatures();
 
-  const axRes = await session.call("Accessibility.getFullAXTree", {});
+  const axRes = await cdpCall(client, "Accessibility.getFullAXTree", {});
   if (!axRes.success) return "";
   const rawNodes = axRes.data.nodes;
   const slim = buildTree(rawNodes, { interestingOnly: true, maxNodes: 1000 });