Merge docs-roadmap-exhausted: mark HCAL roadmap exhausted

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC

docs/plans/hcal-roadmap.md

@@ -9,7 +9,28 @@ HCAL replacement, built on the **2023 R2 gRPC transport**. Derived from
 > protocol serializer/parser + golden-byte unit test + an env-gated live integration
 > test against the local Historian.
 
-## Progress (updated 2026-06-21)
+## Status: roadmap exhausted (2026-06-22)
+
+The reachable surface is **complete**. M0/M1/M2/M3 are done and live-verified; M4 R4.1 (store-forward
+outbox), R4.3 (measured idle-state SF status), and R4.4 (redundancy) are shipped and **merged to
+`main`**; and the follow-on `grpc-tooling-completion.md` plan is fully executed (writes, ReadEvents,
+GetConnectionStatus, the extended-property read-parser fix — all done or bounded-out). The transport
+matrix in the top-level `README.md` is the authoritative per-operation status.
+
+**Nothing left is a pure code task** — every remaining item is gated:
+
+- **Infra-gated** (needs a different live server): gRPC event *row* retrieval (`StartEventQuery`
+  succeeds but `GetNextEventQueryResultBuffer` long-polls — needs an **event-bearing** 2023 R2 server);
+  R4.3 active-SF *magnitude* (needs an **SF-active** server / the D2 storage-engine console handle).
+- **Capture-gated** ("capture before guessing wire bytes"): `SendEvent` over gRPC (no distinct RPC;
+  framing uncaptured).
+- **Architecturally walled** (no client-side fix): `ExecuteSqlCommand` over gRPC (server-side
+  `CSrvDbConnection` fault; a `RegisterTags` prime does not clear it); R4.2 revision *edits*
+  (storage-engine-pipe-only on both transports).
+- **Out of scope until a demand signal**: `ReadBlocks` (`StartBlockRetrievalQuery`, never captured);
+  `DeleteTagExtendedProperties` (server-blocked on WCF).
+
+## Progress (updated 2026-06-22)
 
 - ✅ **R0.6 version gate** — `HistorianServerVersionGate` + `HistorianClientOptions.VerifyServerInterfaceVersion`;
   fail-closed on connect, wired into both WCF and gRPC paths. Supported versions are