docs: R-97 shipped; N.5 gains its four legs; ops results recorded

R-97 collapsed to its shipped one-liner in ROADMAP and closed in OPEN-ITEMS.

PROMPT-TEMPLATE N.5 now names FOUR coupled artifacts instead of two: the
capability map, ROADMAP, the owning architecture doc (ruled as S-1 in CONTEXT.md
but never reflected in the template CC actually reads, so it bound nobody), and
OPEN-ITEMS.md. Tasks must now report which register rows they opened, closed or
re-ranked.

Ops: R-90 swap done (interim; CX33 still blocked), R-95 mitigation armed but zero
snapshots taken so it moves to WATCHING rather than closed, R-91 gate still not
satisfied. CONTEXT.md datastore path corrected to /mnt/pbs-datastore.

documentation/PROMPT-TEMPLATE.md

@@ -326,9 +326,9 @@ Decisions made, architectural state, what's next.
 `<repo>/README.md` if architecture/features changed; authoritative architecture/feature docs in
 `felhom.eu/documentation/{architecture,controller}/`. Spikes/audits → `felhom.eu/documentation/audits/`.
 
-### N.5 Capability map + backlog (end-of-session checklist — easy to forget)
-If the task **changed what the platform can do** (new/removed capability, or a capability moved
-status), update in the SAME session:
+### N.5 The coupling rule — FOUR artifacts, same session (end-of-session checklist)
+If the task **changed what the platform can do** (new/removed capability, a capability moved status,
+or **what is open changed**), update **all four** in the SAME session:
 - **`architecture/00-capability-map.md`** — add/adjust the affected *scenario* row with the correct
   **status** (PROVEN-LIVE requires an `audits/`|`tests/` citation; else IMPLEMENTED/PARTIAL) and an
   evidence citation. A leg not exercised live → PARTIAL/IMPLEMENTED with a note saying which leg and
@@ -337,6 +337,16 @@ status), update in the SAME session:
   collapse a now-shipped item to its one-liner + version, and honor the **coupling rule** (every
   roadmap item names the map row it flips; every map gap row points back by ID). Parked sub-features
   (e.g. an alternative transport, an agent-plane leg) go as a note under the owning arc's item.
+- **the owning `architecture/*.md`** — ruled as **S-1** in `CONTEXT.md` (2026-07-26, R-81): any task
+  that changes an **architectural contract** (tiers, targets, cadences, trust boundaries) updates the
+  owning design doc in the same session. It was ruled but never written here, in the template CC
+  actually reads — so it bound nobody. Now it does.
+- **`backlog/OPEN-ITEMS.md`** — the register, and the single source of truth for open work. A task
+  that changes what is open without touching it re-creates exactly the thread-loss the register was
+  built to solve: `REPORT.md` is overwritten every session, so nothing durable may live only there.
+
+**Report which `OPEN-ITEMS.md` rows the task opened, closed or re-ranked** (§15). Every row carries
+an owner — a row nobody owns is how items got lost in the first place.
 
 ### N.6 Website version bump (if controller/hub version is shown on the site).