[docs] Selenium 5 release charter (#17717)

* [docs] add Selenium 5 release charter

* [docs] reframe classic fallback as out-of-scope partial BiDi support

* [docs] clarify Selenium Manager released API scope in charter

Author: titusfortner

docs/plans/selenium-5.md

@@ -0,0 +1,73 @@
+# Selenium 5 Release Charter
+
+- Status: Proposed
+- Owner: Selenium Technical Leadership Committee (TLC)
+- Discussion: https://github.com/SeleniumHQ/selenium/pull/17717
+
+## Purpose
+
+Selenium 5 is a focused alignment release: the bindings converge on consistent behavior across
+languages. It follows the project's existing deprecation policy — provide a replacement, mark the
+old path deprecated, and remove it only after two releases — and is not an occasion for
+gratuitous breaking changes.
+
+This document is the index of the decisions that define Selenium 5. Each needs an accepted ADR to
+settle its cross-binding design, then implementation in every binding — Java, JavaScript, Python,
+Ruby, and .NET — with behavior consistent and implementation idiomatic per language. A decision is
+marked _ADR pending_ until its record is accepted, at which point this charter is updated to link
+it. An ADR does not name a milestone; this charter records what belongs to Selenium 5.
+
+## Required for release
+
+### BiDi support boundary — _ADR pending_
+
+How the WebDriver BiDi protocol is exposed to users across the bindings. The ADR sets where the
+boundary sits between supported Selenium API and internal implementation, and how each binding
+marks it.
+
+### Network async/event API — _ADR pending_
+
+The cross-binding API for adding, removing, and clearing handlers for requests, responses, and
+authentication.
+
+### Script and logging async/event API — _ADR pending_
+
+The cross-binding API for pinned scripts (pin / unpin / execute) and for console-message,
+JavaScript-error, and DOM-mutation handlers.
+
+### Selenium Manager released API — _ADR pending_
+
+Formalize the interface and behaviors required to drop the Beta label and release independently of
+the bindings.
+
+## Out of scope
+
+These are deferred, not rejected: none blocks Selenium 5.
+
+### Full classic-over-BiDi migration
+
+Routing every classic command through BiDi.
+
+### Partial BiDi implementation support
+
+What it means to support a remote end that does not implement every BiDi feature — choosing the
+BiDi or Classic path per session (not every command can switch mid-session), for older browsers or
+drivers with incomplete BiDi. Part of the classic-over-BiDi migration.
+
+### DevTools deprecation
+
+Deprecating or removing DevTools (CDP) support.
+
+### Convenience layers on the core APIs
+
+Higher-level helpers built on the network and script/event primitives — for example task-oriented
+network actions (`mock`, `block`, `redirect`) and one-shot event waiters (`expect_*`).
+
+### Browser context API
+
+A high-level API for managing browsing contexts — for example exposing them as handle objects.
+
+### Capability mapping
+
+High-level APIs over individual BiDi capability modules — permissions, storage, emulation, user
+prompts.