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, 34 insertions, 0 deletions

diff --git a/test/util/check-boundaries-test.ts b/test/util/check-boundaries-test.ts
index b42baa0..f9eb7eb 100644
--- a/test/util/check-boundaries-test.ts
+++ b/test/util/check-boundaries-test.ts
@@ -97,6 +97,40 @@ describe("boundary check", () => {
     assert.equal(checkSource([{ path: "a.ts", text }], noExemptions).length, 0);
   });
 
+  test("flags a tool reaching the session directly", () => {
+    const forms = [
+      "const r = await client.session().call(\"DOM.resolveNode\", { backendNodeId: id });",
+      "const r = await client.session().callBrowser(\"Target.getTargets\");",
+      "const r = await client.session().callOnTarget(\"Page.enable\", {}, sid);",
+      "const r = await session.call(\"Accessibility.getFullAXTree\", {});",
+      "const r = await session.callBrowser(\"Browser.getWindowForTarget\", { targetId });",
+    ];
+    for (const text of forms) {
+      const v = checkSource([{ path: "src/domains/thing.ts", text }], noExemptions);
+      assert.equal(v.some((x) => x.rule === "raw-cdp-call"), true, text);
+    }
+  });
+
+  test("flags a tool calling evaluateJs directly", () => {
+    const v = checkSource(
+      [{ path: "src/domains/thing.ts", text: "const r = await client.evaluateJs(expr);" }],
+      noExemptions,
+    );
+    assert.equal(v.some((x) => x.rule === "raw-evaluate"), true);
+  });
+
+  test("does not flag the session layer, which owns the session", () => {
+    const text = 'const r = await session.callBrowser("Target.getTargets");\nawait client.evaluateJs(expr);';
+    for (const path of ["src/client.ts", "src/cdp/session.ts", "src/cdp/target-factory.ts"]) {
+      assert.equal(checkSource([{ path, text }], noExemptions).length, 0, path);
+    }
+  });
+
+  test("does not mistake Function.prototype.call in an evaluated snippet for a CDP call", () => {
+    const text = "const expr = `${prelude} ${opts.fnBody} }).call(el, __arg); })()`;";
+    assert.equal(checkSource([{ path: "src/domains/form.ts", text }], noExemptions).length, 0);
+  });
+
   test("reports the 1-indexed line number and the trimmed text", () => {
     const v = checkSource([{ path: "a.ts", text: "const a = 1;\n  const b = c as any;" }], noExemptions);
     assert.equal(v[0]?.line, 2);