feat(410): the server orients with a client-neutral index; the live context carries live state only (#4030)

Step 3 of milestone 410 "One owner per piece of guidance".

_INSTRUCTIONS is rewritten as an index for every MCP client (1,597 of 2,000
chars): orient, rules, recall, record, plan, ids, reuse, UI, report. Each
line names its tool, and the block says every reflex is stated in full in
the using-scribe skill and in each tool description.
- names no client: CLAUDE.md, auto-memory and "the client injects ~2k
  chars" are gone
- gains the two reflexes it lacked: records that cite each other go through
  create_records with {{ref:N}}, and reports start from `placement`

The comment block above it now explains ownership (decision #4027) instead of
accumulating per-milestone trade history, and keeps the budget and its
reason (#2562).

build_session_context states only what the server knows about this session:
the active project and open work, its design system, an unbound-repo hint,
or that no project is bound. Removed: the "you are not holding the
operator's rules" section, the closing "Reflex: search Scribe" line, the
design-system usage sentence, and the plugin-specific header. using-scribe
owns all of that. The truncation note no longer restates the rules ask.

Tests: a pin that the live context carries no rules reflex; the cap test
drives truncation through the unbound-repo hint, since a bare session is now
one line; the budget test message describes the index.

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

src/scribe/services/plugin_context.py

@@ -2160,30 +2160,18 @@ async def build_session_context(
     on each write so the server could say whether the resident rules had
     moved; nothing is resident now, so nothing can have moved, and a rule is
     re-retrieved at the moment it applies rather than held and aged.
-    `context` is markdown ready to drop into `additionalContext`; it is capped
-    at _MAX_CHARS with an explicit truncation note so the hook can pass it
-    through verbatim.
-    """
-    lines: list[str] = [
-        "# Scribe — standing session context (auto-injected by the Scribe plugin)",
-        "",
-        "You are working with Scribe, the operator's self-hosted second brain.",
-        "",
-        "## You are not holding the operator's rules",
-        "",
-        "No rule has been loaded into this session, and that is deliberate. "
-        "Rules arrive when something you are about to do makes one relevant — "
-        "a command you are about to run, code you are writing, or what the "
-        "operator just asked for. On most turns none will, and that is the "
-        "surface working rather than failing.",
-        "",
-        "**\"No rule arrived\" means \"nothing matched\" — never \"there is no "
-        "rule.\"** Before a consequential act, one that is hard to reverse or "
-        "outward-facing, `search(content_type=\"rule\")` is how you ask. "
-        "Retrieval runs on its own and is a convenience; asking is what you do "
-        "when it matters and nothing has spoken.",
-    ]
+    `context` is markdown an adapter can drop into its session verbatim; it
+    is capped at _MAX_CHARS with an explicit truncation note.
 
+    LIVE STATE ONLY (decision #4027, milestone 410). This used to open with the
+    rules reflex and close with a recall reflex — a fifth copy of guidance the
+    using-scribe skill owns, arriving in every session beside the other four.
+    It now says only what the server alone knows about THIS session: the
+    active project, its open work, its design system, or that the working repo
+    is unbound. How to work with Scribe is the skill's to say, and it says it
+    once.
+    """
+    lines: list[str] = ["# Scribe — live session state"]
 
     project_dict: dict | None = None
     if project_id:
@@ -2222,9 +2210,7 @@ async def build_session_context(
                         f"(id {design['id']}){inherits}",
                         f"{design['token_count']} tokens"
                         + (f" across {groups}" if groups else "")
-                        + ". This project's UI is built from these, not from "
-                        "literals — reach for a token before writing a colour, "
-                        "size, radius or duration by hand.",
+                        + ".",
                         f"Values: `resolve_design_system({design['id']})` · "
                         f"stylesheet: `get_design_system_stylesheet({design['id']})` "
                         f"· the prose (aesthetic, voice, where the accent may "
@@ -2241,18 +2227,12 @@ async def build_session_context(
             "(call `list_projects` to find the id) and future sessions here will "
             "auto-load that project's context.",
         ]
-
-    lines += [
-        "",
-        "Reflex: search Scribe (search / list_tasks / list_notes, scoped to the "
-        "active project) before answering or starting work; prefer UPDATING an "
-        "existing note/rule over creating a new one.",
-    ]
+    else:
+        lines += ["", "No Scribe project is bound to this working directory."]
 
     context = "\n".join(line for line in lines if line is not None)
     if len(context) > _MAX_CHARS:
-        context = context[:_MAX_CHARS].rstrip() + \
-            "\n\n…(truncated — ask with search(content_type=\"rule\"))"
+        context = context[:_MAX_CHARS].rstrip() + "\n\n…(truncated)"
 
     return {
         "context": context,