Docs: record Phase Upsilon W1; carry forward W2/W3 constraints; SEPT_VERIFY section 7

docs/COMPLETED.md

@@ -1833,3 +1833,19 @@ project sample-rate change while the plugin is inactive re-stamps in place rathe
 reloading from disk.
 
 Not DAW-verified — checks are tracked in `docs/SEPT_VERIFY.md` §6.
+
+### Υ-W1 — The bank-root seam, and the instrument's own project
+
+**T1 `bank-root-seam`:** a pure `capture::bankRootFor(rppPath, unsavedRoot)` and one shell
+resolver, `bankRootOf(ReaProject*)` (`src/shell/persist/bank_root`), now carry every
+extension-side bank-directory lookup; `session` stores `lastBankRoot_` for Save-As
+relocation. No behaviour change — the only visible delta is that the refused-render console
+path prints lowercase on Windows. Detail: `src/shell/persist/CLAUDE.md`.
+
+**T2 `instrument-own-project`:** ReaSampler 9000 now resolves bank-relative sample paths
+against its OWN project (`getReaperParent(3)`, matched among the open projects) rather than
+the focused tab — fixing an instance in a background tab reading the wrong project's folder.
+It falls back to the focused tab only when REAPER reports no parent project. The ordered
+candidate-root list (`src/core/instrument/map/sample_roots`) is ready for Υ-W2's temp-bank
+root. Detail: `src/shell/instrument/CLAUDE.md`. Not DAW-verified — checks are tracked in
+`docs/SEPT_VERIFY.md` §7.