feat(410): the Claude Code plugin becomes a thin adapter (#4031)

Step 4 of milestone 410 "One owner per piece of guidance". The plugin's
static session context was a second copy of using-scribe and the server
index. It now says only what Claude Code needs said: 8,705 -> 1,791 chars.

scribe_static_context.md:
- points at using-scribe for how to work with Scribe, and names the process
  skills
- Claude Code specifics: keep one copy in Scribe rather than CLAUDE.md or
  auto-memory (leave auto-memory at its default); injected lines are
  retrieval, not the whole set; compact at clean seams; stored Processes
  arrive as scribe-proc-* skills with /scribe:sync; say so when the tools
  are unavailable
- retired: the restated reflexes, "how the surfaces divide the work", and
  the "follow the surface that assumes least" precedence (decision #4027)

Hook behaviour is unchanged. The SessionStart hook header says what the
static tier now carries, and the unreachable-instance status points at the
using-scribe skill instead of "the standing guidance above".

README and manifest describe the plugin as the Claude Code adapter over the
shared, client-neutral skills. Fixed along the way: the README said the
SessionStart hook "injects your rules" and suggested disabling auto-memory,
both contradicting the product since milestone 394.

Tests: the session-start rules guards now pin the owner (using-scribe) and
the index (_INSTRUCTIONS) rather than every surface; the Systems-reflex and
snippet-trigger guards pin their owners; the reporting-reflex guard pins
using-scribe. The loss guard and client-neutral guard stay green. Plugin
version minted.

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

plugin/README.md

@@ -5,13 +5,16 @@ instance into a first-class Claude Code extension:
 
 - **MCP tools** over your notes, tasks, projects, milestones, systems, and
   rulebook (the `scribe` server).
-- **Session-start push channel** — a `SessionStart` hook injects your
-  rules + active-project context so Scribe surfaces *without being asked*.
+- **Session-start push channel** — a `SessionStart` hook injects the
+  active project's live state (from the server) and this adapter's short
+  Claude Code guidance, so Scribe surfaces *without being asked*. Rules are
+  never preloaded; they arrive by retrieval when your work matches one.
 - **Prior-art recall on writes** — a `PreToolUse` hook on Write/Edit checks the
   file about to be written against your recorded snippets (what's kept at that
   path, and what resembles the code) and offers them before the helper is
   rewritten. Titles only, never blocks the edit.
-- **Universal process-skills** — using-scribe, writing-plans, reporting-back
+- **The shared Scribe skills** — client-neutral Agent Skills, the same files
+  any client's package would ship: using-scribe, writing-plans, reporting-back
   (reply to the operator in a shape that says where the work stands),
   systematic-debugging, verification, brainstorming, reusing-code (record and
   recall reusable code as snippets). Replaces superpowers.
@@ -20,8 +23,15 @@ instance into a first-class Claude Code extension:
   stub fetches the live procedure via `get_process`. Refreshed each session and
   on demand with `/scribe:sync`.
 
-It is designed so you can uninstall `superpowers` and disable auto-memory and
-depend on neither.
+It is designed so you can uninstall `superpowers` and depend on Scribe instead
+of auto-memory — leave auto-memory at its default; Scribe replaces its job by
+holding the one copy, not by switching it off.
+
+**How the pieces divide the work** (decision #4027): the Scribe server orients
+every MCP client and serves live state; the skills in `skills/` state every
+reflex in full and name no client; this plugin is the Claude Code adapter —
+hooks that deliver at the right moment, `/scribe:sync`, and the few things only
+Claude Code needs said (`hooks/scribe_static_context.md`).
 
 ## Install