feat: add browser_read_page reader-mode tool

URL (or owned targetId) → clean main-article text with nav/ads/footer
boilerplate stripped, via a dependency-free readability heuristic. DOM walk
lives in an in-page capture expression; scoring/selection is a pure, fixture-
tested function (link-density + boilerplate-ancestor filtering, body-text
fallback for structure-less pages). Reuses the isolated-attach lifecycle;
registered unserialized (safe concurrent read). 10 extractor unit scenarios.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2 files changed, 27 insertions, 0 deletions

diff --git a/test/deep-research/fixtures/article-capture.json b/test/deep-research/fixtures/article-capture.json
new file mode 100644
index 0000000..df9c67c
--- /dev/null
+++ b/test/deep-research/fixtures/article-capture.json
@@ -0,0 +1,17 @@
+{
+  "url": "https://blog.example.com/how-cdp-works",
+  "title": "How the Chrome DevTools Protocol Works",
+  "blocks": [
+    { "kind": "other", "text": "Home Products Blog About Contact", "linkTextLength": 33, "inBoilerplate": true },
+    { "kind": "heading", "text": "How the Chrome DevTools Protocol Works", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "paragraph", "text": "The Chrome DevTools Protocol lets tools instrument, inspect, and control Chromium-based browsers over a WebSocket connection.", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "paragraph", "text": "Each command targets a domain such as Page, Runtime, or Network, and receives a structured JSON response that the client correlates by id.", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "heading", "text": "Sessions and Targets", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "paragraph", "text": "A target is a page or worker; attaching to one yields a session id that scopes subsequent commands to that target without disturbing others.", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "listitem", "text": "Attach with Target.attachToTarget", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "listitem", "text": "Drive with Runtime.evaluate", "linkTextLength": 0, "inBoilerplate": false },
+    { "kind": "paragraph", "text": "Subscribe here for our newsletter and follow us on social media for updates", "linkTextLength": 55, "inBoilerplate": true },
+    { "kind": "other", "text": "Copyright 2026 Example Inc. Privacy Terms Cookies", "linkTextLength": 24, "inBoilerplate": true }
+  ],
+  "bodyText": "Home Products Blog How the Chrome DevTools Protocol Works The Chrome DevTools Protocol lets tools instrument inspect and control browsers Copyright 2026"
+}
diff --git a/test/deep-research/fixtures/no-article-capture.json b/test/deep-research/fixtures/no-article-capture.json
new file mode 100644
index 0000000..d367b7e
--- /dev/null
+++ b/test/deep-research/fixtures/no-article-capture.json
@@ -0,0 +1,10 @@
+{
+  "url": "https://app.example.com/dashboard",
+  "title": "Dashboard",
+  "blocks": [
+    { "kind": "other", "text": "Menu", "linkTextLength": 4, "inBoilerplate": true },
+    { "kind": "listitem", "text": "Widget A", "linkTextLength": 8, "inBoilerplate": true },
+    { "kind": "listitem", "text": "Widget B", "linkTextLength": 8, "inBoilerplate": true }
+  ],
+  "bodyText": "Dashboard Widget A Widget B Your account is active. Usage this month is within limits and no action is required at this time from you."
+}