docs(browser): add CDP recovery boundaries

[MagMueller]

Problem

Two CDP failures require different recovery layers:

• -32001 means the attached target session is stale even when the browser socket remains usable. Reconnecting the root socket does not replace that target session.
• A persistent ERR_TUNNEL_CONNECTION_FAILED belongs to the browser proxy route. Reloading, reattaching, or reconnecting to the same endpoint preserves that route.

Without this distinction, an agent can repeatedly retry the wrong layer.

Change

• Tell the agent to re-list targets, reattach, and retry once after -32001.
• Tell the agent to inspect Page.navigate.errorText and switch source or replace the browser after a persistent tunnel failure.
• Keep recovery in the existing skill: no automatic retry machinery or new abstraction.

Validation

• bun typecheck in packages/bcode-browser
• Repository pre-push typecheck with Bun 1.3.14
• git diff --check

---

Summary by cubic

Clarified CDP recovery boundaries in the browser execution skill docs to stop retries at the wrong layer. For -32001, list targets again, reattach with session.use(...), and retry once (note: session.connect() does not replace a stale target session); for Page.navigate with errorText like persistent ERR_TUNNEL_CONNECTION_FAILED, treat it as a proxy route issue and switch source or replace the cloud browser instead of reloading, reattaching, or reconnecting.

^{Written for commit 8f5d2b9. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}