feat(plugin): Phase 4 — Scribe Processes auto-surface as local skills

#755 Phase 4. Saved Scribe Processes (DRY pass, Drift Audit, …) now surface as
auto-triggered Claude Code skills instead of pull-only get_process calls.

Design correction vs the plan: stubs live in the USER's ~/.claude/skills/, NOT
plugin/skills/_instance/. The plugin is git-cloned and identical per install, so
instance-specific generated files can't ride in it; personal skills are
live-detected within the session (verified via claude-code-guide). MCP prompts
were the alternative but are pull-only (no relevance auto-surface), so skills are
the right primitive.

- backend: GET /api/plugin/processes manifest (services/plugin_context.
  build_process_manifest) — {name, slug, description} per Process; description is
  the auto-surface trigger (title + preview); slugs deduped, blanks skipped.
- plugin: scribe_sync_processes.sh writes ~/.claude/skills/scribe-proc-<slug>/
  SKILL.md (body = "call get_process(name), follow verbatim") and PRUNES stale
  scribe-proc-* stubs. Fail-open + silent; a transient fetch failure never wipes
  existing stubs. Runs as a 2nd SessionStart hook + via the /scribe:sync command.
- plugin.json 0.1.7 → 0.1.8; README updated.
- tests: build_process_manifest (render, slug dedupe, blank-title skip, preview
  truncation). Sync script's write+prune validated in isolation (plugin/** is not
  CI-covered): correct stubs created, stale pruned, unrelated skills untouched.

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

src/scribe/routes/plugin.py

@@ -57,6 +57,20 @@ async def session_context():
     return jsonify(result)
 
 
+@plugin_bp.get("/processes")
+@login_required
+async def process_manifest():
+    """Stored Processes as skill-stub specs for the plugin's sync script.
+
+    The plugin's `scribe_sync_processes.sh` (run at SessionStart and via the
+    `/scribe:sync` command) curls this and writes one auto-surfacing local skill
+    per Process into ~/.claude/skills/. See services/plugin_context.
+    build_process_manifest. A read-scoped API key suffices.
+    """
+    result = await plugin_ctx_svc.build_process_manifest(g.user.id)
+    return jsonify(result)
+
+
 @plugin_bp.get("/marketplace-url")
 @login_required
 async def get_marketplace_url():

src/scribe/services/plugin_context.py

@@ -14,10 +14,13 @@ index alone already steers behavior.
 """
 from __future__ import annotations
 
+import re
+
 from sqlalchemy import select
 
 from scribe.models import async_session
 from scribe.models.rulebook import RulebookTopic
+from scribe.services import knowledge as knowledge_svc
 from scribe.services import notes as notes_svc
 from scribe.services import projects as projects_svc
 from scribe.services import rulebooks as rulebooks_svc
@@ -25,6 +28,59 @@ from scribe.services import rulebooks as rulebooks_svc
 # Defensive cap below Claude Code's 10k additionalContext limit.
 _MAX_CHARS = 9000
 
+# Max chars of a Process body to fold into the auto-surface description.
+_PROC_PREVIEW_CHARS = 200
+
+
+def _slugify(text: str) -> str:
+    """kebab-case slug for a skill directory name (a-z0-9 + single hyphens)."""
+    s = re.sub(r"[^a-z0-9]+", "-", (text or "").lower()).strip("-")
+    return s or "process"
+
+
+async def build_process_manifest(user_id: int) -> dict:
+    """List the user's stored Processes as auto-surfacing skill-stub specs.
+
+    The plugin's sync script (scribe_sync_processes.sh) writes one
+    ~/.claude/skills/scribe-proc-<slug>/SKILL.md per entry — `description` is the
+    auto-surface trigger, and the stub body calls get_process(name) for the live
+    procedure (single source of truth in the DB). Reuses the list_processes query
+    (note_type='process'). Instance-agnostic: derived from whatever Processes the
+    calling install owns, no operator-specific coupling.
+
+    Returns {"processes": [{id, name, slug, description}], "total": int}.
+    Slugs are unique within the result (a collision gets an -<id> suffix).
+    """
+    items, _ = await knowledge_svc.query_knowledge(
+        user_id=user_id, note_type="process", tags=[], sort="modified",
+        q=None, limit=100, offset=0,
+    )
+    procs: list[dict] = []
+    seen: set[str] = set()
+    for it in items:
+        title = (it.get("title") or "").strip()
+        if not title:
+            continue
+        slug = _slugify(title)
+        if slug in seen:
+            slug = f"{slug}-{it['id']}"
+        seen.add(slug)
+
+        preview = " ".join((it.get("snippet") or "").split())
+        if len(preview) > _PROC_PREVIEW_CHARS:
+            preview = preview[:_PROC_PREVIEW_CHARS].rstrip() + "…"
+        description = (
+            f'Run the operator\'s saved Scribe process "{title}".'
+            + (f" {preview}" if preview else "")
+            + f' Use when {title}-type work is requested, or when asked to run'
+            f' the "{title}" process.'
+        )
+        procs.append({
+            "id": it["id"], "name": title, "slug": slug,
+            "description": description,
+        })
+    return {"processes": procs, "total": len(procs)}
+
 
 async def _topic_titles(topic_ids: set[int]) -> dict[int, str]:
     """Map topic_id -> title for the given ids (live topics only)."""