docs(STATE-WP-0079): archive suggestion-backlog history, record E1 status

Slice E1 was already half-retired: mutations 410 since CUST-WP-0061-T06,
reads held open only to keep the history reachable. That history is now
archived fleet-side, so the reads can go.

Records a dependency the inventory's 17-item count misses: the suggestions
dashboard page is live and referenced from index.md and wsjf-triage.md, so
E1's removal must sequence with the UI slices A4/B5 rather than ahead of them.

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

docs/retirement-cutover-slice-plan.md

@@ -178,7 +178,7 @@ D3 is two MCP tools with no dependants; take it opportunistically.
 
 | Slice | Capability | Items | Gate |
 | --- | --- | --- | --- |
-| E1 | `suggestion-backlog` → archive | 17 | caller check; no successor runtime |
+| E1 | `suggestion-backlog` → archive | 17 | history archived 2026-08-20; read surface + dashboard remain |
 | E2 | `work-records-workplan-legacy` → archive | 13 | legacy-meter — candidate rule, see below |
 | E3 | `dashboard-meta` | 1 | none |
 | E4 | `legacy-meter` itself | 9 | **last** — it is the instrument for E2 |
@@ -186,6 +186,24 @@ D3 is two MCP tools with no dependants; take it opportunistically.
 E4 retires only after every other legacy surface is closed; retiring the meter
 first destroys the evidence for the retirements it gates.
 
+### E1 status (2026-08-20)
+
+Already half-retired before this plan: mutations have returned HTTP 410 since
+2026-07-21 (`CUST-WP-0061-T06`), pointing at `POST /intakes/`. Reads were kept
+live so the historical record stayed reachable.
+
+**History is now archived** at `the-custodian/docs/archived-suggestion-backlog.md`
+— all 10 suggestions, 10 notes, and 5 relevance bumps, with each entry's
+migration target. Every entry was `declined` in the intake migration and none
+was promoted, so nothing forward-looking is lost by removing the surface.
+
+**Remaining for E1:** retire the 8 read routes and 6 MCP tools, then drop the 3
+tables at the T06 dump. This has a dependency the inventory's 17-item count does
+not show — `dashboard/src/suggestions.md` is a live page, and `index.md` and
+`wsjf-triage.md` reference it. The dashboard must be updated in the same change
+or the retirement breaks it. Sequence E1's removal with A4/B5 (the UI slices)
+rather than ahead of them.
+
 ### E2 evidence — defect found and partly fixed (2026-08-20)
 
 The window discrepancy flagged on 2026-08-19 was a real defect in

workplans/STATE-WP-0079-retirement-strangler.md

@@ -178,9 +178,19 @@ repo, since State Hub is being archived and the record must outlive it.
 (`GET /workstreams/`, `GET /workstreams/{id}`,
 `GET /workstreams/{id}/dependencies/`, `GET /tasks/?workstream_id`) clear as
 their quiet counters run; earliest is 18 more silent days. Re-capture before
-deciding — the ladder evaluates at review time. Then the remaining `retire`
-inventory items outside E2: `suggestion-backlog` (E1, 17) and `dashboard-meta`
-(E3, 1); `legacy-meter` itself (E4, 9) retires last, being the instrument.
+deciding — the ladder evaluates at review time. **Slice E1 part-executed (2026-08-20):** `suggestion-backlog` history archived
+to `the-custodian/docs/archived-suggestion-backlog.md` — 10 suggestions, 10
+notes, 5 bumps, all `declined` in the 2026-07-21 intake migration, none
+promoted. Mutations already 410 since `CUST-WP-0061-T06`; reads were open only
+to keep that history reachable, which the archive now replaces.
+
+E1's remaining removal (8 read routes, 6 MCP tools, 3 tables) is **coupled to
+the dashboard** — `dashboard/src/suggestions.md` is live and referenced from
+`index.md` and `wsjf-triage.md`. The inventory's 17-item count does not show
+this. Sequence with the UI slices A4/B5, not ahead of them.
+
+Then `dashboard-meta` (E3, 1); `legacy-meter` itself (E4, 9) retires last,
+being the instrument.
 
 ## Stabilization window and archive prep