docs: clarify generic userspace boundary pattern

AI.md

@@ -46,7 +46,7 @@ unfinished work out of `TODO.md` merely because its architecture is documented.
 
 Latest commit in an up-to-date tree:
 
-- `docs: update XAttr/LSA import checklist and userspace boundary rules`
+- `docs: clarify generic userspace boundary pattern`
 
 Compare `git log -1 --format="%s"` with this subject.  If the tree is older,
 check which documentation/import-boundary commits are missing and replay them
@@ -54,15 +54,17 @@ before starting new work.
 
 ## Current patch handoff block
 
-Last completed work block: **XAttr/LSA import checklist and userspace boundary refresh**
+Last completed work block: **Generic userspace boundary pattern refresh**
 
 `AI.md`, `REDESIGN.md` and `nwnss-audit.md` now describe the active
 libnwnss userspace-backend split.  The next concrete implementation step is the
 real XAttr/LSA import from `nss.tar.bz2` and `nss-common.tar.bz2`, while local
-`nwfs` XAttr/quota/salvage code remains adapter material only.  The documented
-follow-on direction is to build quota and salvage userspace boundaries on top of
-that XAttr/LSA foundation rather than treating the current `nwfs` code as the
-semantic source.
+`nwfs` XAttr/quota/salvage code remains adapter material only.  XAttr/LSA is the
+metadata storage/lookup foundation for later quota and salvage boundaries, but
+quota, salvage and namespace unique-name handling remain separate semantic areas
+that follow the same generic companion-file rule: keep original NSS source files
+as original-like as possible, add only small dispatch points, and put backend
+selection in parallel `*Userspace.c` / `*Userspace.h` files.
 
 Ownership boundaries are current: `nwserv` is the process governor, `nwconn` is
 the NCP server, `libnwfs` is the Mars/NCP file wrapper, `libnwnss` is the NSS
@@ -124,21 +126,25 @@ inside `libnwnss`, not `nwfs` migration yet:
 - Do not touch or migrate the existing local `nwfs` XAttr code in this phase;
   `nwfs` will consume the libnwnss semantics later after the libnwnss side is
   tested.
-- Treat the XAttr/LSA import as the foundation for later quota and salvage
-  userspace boundaries.  Quota and salvage ownership stays in `libnwnss`;
-  `libnwfs` only translates Mars/NCP requests to those provider operations.
+- Treat the XAttr/LSA import as the metadata storage/lookup foundation for later
+  quota and salvage userspace boundaries, not as their semantic owner.  Quota
+  and salvage remain separate NSS semantic areas, but their valid OtherFS state
+  should be found through NSS-shaped xattrs or NSS metadata.  `libnwnss` owns
+  those provider operations; `libnwfs` only translates Mars/NCP requests to
+  them.
 - For namespace, keep `libnwnss` as the NSS provider and put Mars/NWFS
   compatibility wrappers in `nwfs` later.  Most namespace helpers are pure
-  string/provider operations; `*_generateUniqueName()` needs a userspace
-  directory collision boundary (`nameSpaceUserspace.c` / `.h`) because HostFS or
-  OtherFS enumeration must not be added directly to the original NSS namespace
-  files.
+  string/provider operations; `*_generateUniqueName()` needs the same generic
+  userspace companion-file pattern because HostFS/OtherFS directory collision
+  lookup may need NSS-shaped xattrs or NSS metadata and must not be added
+  directly to the original NSS namespace files.
 
-- Quota and salvage follow the same ownership split.  `libnwnss` is the NSS
-  provider for quota and salvage semantics imported from `nss`/`nss-common`;
-  `nwfs` is the later Mars wrapper/adapter.  Existing `nwfs` quota and salvage
-  code is only an implementation inventory and must not be treated as
-  provenance or moved wholesale into `libnwnss`.
+- Quota, salvage, namespace unique-name handling and future backend-sensitive
+  NSS functions all follow the same ownership split.  `libnwnss` is the NSS
+  provider for semantics imported from `nss`/`nss-common`; `nwfs` is the later
+  Mars wrapper/adapter.  Existing `nwfs` quota and salvage code is only an
+  implementation inventory and must not be treated as provenance or moved
+  wholesale into `libnwnss`.
 - OtherFS/HostFS quota policy such as Linux `quotactl()`, project-quota or
   metadata-only accounting belongs in parallel userspace boundary files such as
   `lsaQuotaUserspace.c` or `dirQuotasUserspace.c`, not inline in original NSS
@@ -306,11 +312,15 @@ work.
   `nebEventPort.c`, Unicode TAB data (GENERATED PORT DATA from Unicode.org, not
   Novell blobs).  When a PORT entry is found during audit, search for original
   `.c` or `sharedsrc/*.c.h` before accepting the port as final.
-- For LSA/XAttr/COMN I/O backend work, keep imported original files focused on
-  original control flow and small backend decisions.  Put userspace backend
+- For LSA/XAttr/COMN I/O backend work, and for every future NSS function that
+  needs a userspace/backend decision, keep imported original files focused on
+  original control flow and small dispatch points.  Put userspace backend
   selection and host adaptation in separate `*Userspace.c` / `*Userspace.h`
-  files.  `virtualIO` is already the NSS `_ADMIN`/management virtual-file layer;
-  do not reuse that name for future disk/block/`io_uring` backends.
+  files.  Those companions decide whether the operation targets the real
+  NSS/io_uring backend path or an OtherFS/HostFS path, then call the appropriate
+  backend-specific functions.  `virtualIO` is already the NSS `_ADMIN`/
+  management virtual-file layer; do not reuse that name for future disk/block/
+  `io_uring` backends.
 - `*Userspace.c` / `*Userspace.h` companion files have two distinct roles.
   Companions such as `nameSpaceUserspace.c`, `lsaXattrUserspace.c` or
   `dirQuotasUserspace.c` are ALLOWED: they sit alongside the matching imported
@@ -336,9 +346,10 @@ work.
 - `libnwnss` owns NSS provider semantics and the future real NSS backend
   boundaries: FUSE, `io_uring`, HostFS/OtherFS and the explicit
   `*Userspace.c` / `*Userspace.h` companion files for XAttr, namespace
-  uniqueness, quota and salvage.  `nwnssmount` is the future FUSE mount
-  consumer of `libnwnss`; `nwnssmu` is the future TUI management utility for
-  admin, inspect, repair, quota, salvage, namespace and XAttr operations.
+  uniqueness, quota, salvage and any later backend-sensitive NSS operation.
+  `nwnssmount` is the future FUSE mount consumer of `libnwnss`; `nwnssmu` is
+  the future TUI management utility for admin, inspect, repair, quota, salvage,
+  namespace and XAttr operations.
 - `libnwbind` is for bindery identity/storage.  NDS/eDirectory compatibility
   belongs in a future `libnwnds`, backed by `libnwdirectory`; `nwdirectory` is
   the LDAP/TinyLDAP-based directory server.  An `nwnds` process may be added
@@ -385,7 +396,10 @@ work.
   replacement wrappers.
 - Stable namespace state belongs in `netware.metadata`: file ID, parent file ID,
   DOS name, LONG/OS2 name, MAC name, UNIX/backend name, casefold/hash fields and
-  namespace flags.
+  namespace flags.  `*_generateUniqueName()` must use the generic userspace
+  companion-file pattern when it needs HostFS/OtherFS directory collision lookup
+  or metadata/xattr-backed namespace state; do not put that lookup directly into
+  the original NSS namespace source files.
 - Existing Linux files created by Samba, rsync or local admin tools must be
   reconciled by libnwfs watcher/scanner work, not by a private side database.
 - MAC namespace is a namespace/stream/metadata problem, not a transport problem.