feat(STATE-WP-0079): retire the suggestion-backlog surface (slice E1)

History is archived fleet-side, so the read surface has no remaining job.

- api/routers/suggestions.py: whole prefix 410s with a pointer to intake and
  to the archive; the router drops from 176 lines to a stub
- mcp_server: the 6 suggestion tools removed outright rather than stubbed --
  a retired tool that still appears in the tool list costs every agent
  session context on every call, which is the opposite of retiring it
- write_idempotency: 5 /suggestions rules dropped
- dashboard: suggestions.md deleted, nav entry removed, reference.md and
  wsjf-triage.md updated; docs/suggestions.md rewritten as archive pointer
- tests: two tests pinned the old read-live behaviour and now pin the
  retirement contract instead

Tables stay: they are retire/archive in SHR-INV-0001 and are captured by the
final dump at T06.

Untouched, and worth knowing during cutover: ui-feedback.md / todo.md
'suggestions' are Shift+click dashboard feedback backed by technical_debt, a
different entity that shares the word. E3 (dashboard-meta) is that page; its
owner is state-hub-until-cutover so it retires at the T06 window, not now.

Full suite 612 passed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

mcp_server/server.py

@@ -1222,108 +1222,20 @@ def get_next_steps() -> str:
 
 
 # ---------------------------------------------------------------------------
-# Demand-weighted suggestion backlog (STATE-WP-0061)
+# Suggestion backlog — RETIRED (STATE-WP-0079-T05, slice E1)
 # ---------------------------------------------------------------------------
-
-@mcp.tool()
-def list_suggestions(
-    domain: str | None = None,
-    stage: str | None = None,
-    rank: str | None = None,
-    limit: int = 50,
-) -> str:
-    """List persisted suggestions, optionally ranked by WSJF."""
-    return json.dumps(
-        _get("/suggestions", {
-            "domain": domain,
-            "stage": stage,
-            "rank": rank,
-            "limit": limit,
-        }),
-        indent=2,
-    )
-
-
-@mcp.tool()
-def create_suggestion(
-    domain: str,
-    title: str,
-    description: str | None = None,
-    origin_ref: str | None = None,
-    workplan_id: str | None = None,
-    base_value: float = 3.0,
-    job_size: float = 3.0,
-) -> str:
-    """Retired (CUST-WP-0061-T06, 2026-07-21): suggestions are read-only
-    legacy. Use create_intake instead (kind: intake per canon/standards/
-    work-record-types_v0.1.md). This call now 410s server-side; kept only
-    so old callers get a clear error instead of a missing tool."""
-    return json.dumps(_post("/suggestions", {
-        "domain": domain,
-        "title": title,
-        "description": description,
-        "origin_ref": origin_ref,
-        "workplan_id": workplan_id,
-        "base_value": base_value,
-        "job_size": job_size,
-    }), indent=2)
-
-
-@mcp.tool()
-def vet_suggestion(suggestion_id: str, note: str, author: str | None = None) -> str:
-    """Retired (CUST-WP-0061-T06, 2026-07-21): suggestions are read-only
-    legacy. There is no vet/route equivalent needed for intake — use
-    route_intake directly. This call now 410s server-side."""
-    return json.dumps(_post(f"/suggestions/{suggestion_id}/vet", {
-        "note": note,
-        "author": author,
-    }), indent=2)
-
-
-@mcp.tool()
-def decline_suggestion(suggestion_id: str, note: str, author: str | None = None) -> str:
-    """Retired (CUST-WP-0061-T06, 2026-07-21): suggestions are read-only
-    legacy. Use close_intake(outcome="declined") instead. This call now
-    410s server-side."""
-    return json.dumps(_post(f"/suggestions/{suggestion_id}/decline", {
-        "note": note,
-        "author": author,
-    }), indent=2)
-
-
-@mcp.tool()
-def promote_suggestion_to_task(
-    suggestion_id: str,
-    note: str | None = None,
-    task_title: str | None = None,
-    author: str | None = None,
-) -> str:
-    """Retired (CUST-WP-0061-T06, 2026-07-21): suggestions are read-only
-    legacy. Use route_intake then the promote-intake CLI
-    (scripts/promote_intake.py --to task) instead. This call now 410s
-    server-side."""
-    return json.dumps(_post(f"/suggestions/{suggestion_id}/promote", {
-        "note": note,
-        "task_title": task_title,
-        "author": author,
-    }), indent=2)
-
-
-@mcp.tool()
-def bump_suggestion_relevance(
-    suggestion_id: str,
-    reason: str | None = None,
-    author: str | None = None,
-) -> str:
-    """Retired (CUST-WP-0061-T06, 2026-07-21): suggestions are read-only
-    legacy — relevance/WSJF scoring has no intake equivalent yet (ordering
-    is lane+priority+age per the founder-reviewed architecture draft).
-    This call now 410s server-side."""
-    return json.dumps(_post(f"/suggestions/{suggestion_id}/bump-relevance", {
-        "reason": reason,
-        "author": author,
-    }), indent=2)
-
+# The six suggestion tools (list/create/vet/decline/promote/bump) were removed
+# on 2026-08-20. Mutations had 410'd since CUST-WP-0061-T06; the reads existed
+# only to keep the historical backlog reachable, and that history is now
+# archived at the-custodian/docs/archived-suggestion-backlog.md.
+#
+# Successor: the intake work-record entity — create_intake / route_intake /
+# close_intake, and scripts/promote_intake.py --to task. See
+# canon/standards/work-record-types_v0.1.md.
+#
+# Kept as a comment rather than as 410 stubs: a retired tool that still appears
+# in the tool list costs every agent session context on every call, which is the
+# opposite of retiring it.
 
 # ---------------------------------------------------------------------------
 # Dependency graph tools (S1.4)