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NextBSD path-domain conformance — adopt the gershwin four-domain layout

Coverage plan for a bounded, agreed change: make NextBSD's filesystem paths obey gershwin's four-domain model (/System/Library, /Local/Library, /Network/Library, ~/Library) instead of Apple's convention where the bare /Library is the Local domain. Concretely: every bare /Library/X becomes /Local/Library/X; everything already under /System/Library stays. This doc is the org-wide audit result (all 9 nextbsd-redux repos inspected) and the exact change surface. Status: implemented in nextbsd-userland#19 (33 sites, grep-clean, CI-gated) — this page is now the decision record behind that PR.

1. The target: gershwin's four domains & the one rename rule

The gershwin tools-make FilesystemLayout roots resources in four domains. NextBSD adopts the same shape, so there is exactly one mechanical rule for the OS side:

Domain	Root (gershwin)	Meaning	NextBSD action
System	/System/Library	OS-provided	unchanged — already correct everywhere
Local	/Local/Library	this machine, admin-installed	bare /Library/X → /Local/Library/X
Network	/Network/Library	network-shared	unused today — reserve, no change
User	~/Library	per-user	unchanged — already matches

The rule: a path is a rename candidate iff it starts with a bare /Library/ (Apple's Local domain). Anything already qualified — /System/Library, ~/Library, /var/…/Library — is left alone. The audit below applies exactly this filter across the org.

2. Org-wide coverage matrix (all 9 repos)

Every repository in the nextbsd-redux org was inspected (fresh shallow clones of ground truth, not local checkouts), scoped strictly to the freebsd-launchd-mach variant. Result: the rename surface is confined to the two repos that carry the Darwin userland source. Six repos are already clean; one is out of scope by rule.

Repo	Verdict	Detail
nextbsd-userland	CHANGE	Authoritative source of the candidates — 33 bare-/Library hits ⇒ ~12 runtime-behavioral across 6 subsystems (rest are comments/docs/man/tests). Overlay ships only /System/Library.
nextbsd	skip	ISO builder — compiles its own byte-identical copy of the same src/ tree (5,382 files), but src/ is slated for removal when the ISO is redone (future PR). Not touched here. Build scripts only ever create /System/Library.
nextbsd-freebsd-compat	clean	Only /System/Library/Libraries (Lever B, System domain). No bare /Library.
nextbsd-pkg	clean	Only /System/Library/Extensions (kext staging, System domain).
nextbsd-kernel-modules	clean	Kexts placed only into /System/Library/Extensions. Zero bare /Library.
nextbsd-kernel	clean	Zero /Library of any kind; the mach kernel overlay has none.
nextbsd-kernel-toolchain	clean	Zero /Library.
nextbsd-redux.github.io	clean	Zero /Library.
freebsd-src	out of scope	Upstream fork, edit-forbidden by hard rule. NextBSD-authored delta is CI-only (.github/workflows); any /Library is vendored heimdal/clang. (Caveat: GitHub code-search cannot index forks, so this rests on the authored delta being CI-only.)

3. The double-repo question — resolved to one

The audit exposed that the Darwin userland source lives in two repos, which is why "it might not be just one repo" was the right instinct to check. But the decision resolves it cleanly to a single target:

So the earlier lockstep worry is moot: there is one edit, in one repo. The transient window where the shipped ISO still builds the old nextbsd/src strings is acceptable — the affected dirs are empty third-party slots (below), and that tree is on its way out regardless.

4. The rename surface: behavioral sites by subsystem

~12 runtime-behavioral sites (paths actually used at runtime), across six subsystems, all in nextbsd-userland/src. Comments/docs/man-pages/help-strings/tests (~21 more) are cosmetic — update for consistency, but they don't affect behavior.

Subsystem	Site (nextbsd-userland/src)	Literal	Kind
launchd (PID 1)	src/launchd/src/launchd_plist_scan.c:265	"/Library/LaunchDaemons"	boot scan dir
launchd	src/launchd/support/launchctl.c:4122	"/Library/StartupItems"	bootstrap dir create/chmod
SCPreferences	src/libSystemConfiguration/SCPreferences.c:35	PREFS_DEFAULT_DIR "/Library/Preferences/SystemConfiguration"	SC state store (ComputerName / DiskArb; ties to #358)
CoreFoundation	src/libCoreFoundation/CFKnownLocations.c:38,46	CFSTR("/Library/Preferences")	CFPreferences "Any-user"/computer domain
CoreFoundation	src/libCoreFoundation/CFXMLPreferencesDomain.c:241	strncmp(cpath, "/Library/Preferences", 20)	root-owned-write special-case strlen 20
CoreFoundation	src/libCoreFoundation/CFBundle_Resources.c:1245	CFSTR("/Library/Spotlight")	bundle-path compare (vestigial — see mapping)
kext_tools	src/kext_tools/kext.subproj/bootfiles.h:69,73	kLibraryExtensionsDir "/Library/Extensions"; kBootConfig ".../com.apple.Boot.plist"	aux kext dir + boot config
kext_tools	src/kext_tools/kext.subproj/OSKextPrivate.h:57	_kOSKextLibraryExtensionsFolder "/Library/Extensions"	aux kext folder
syslog / ASL	src/syslog/aslcommon/asl_common.c:53	PATH_LIBRARY_LOGS "/Library/Logs/"	log-path prefix test strlen 14
syslog / ASL	src/syslog/aslcommon/asl_common.h:32	_PATH_CRASHREPORTER "/Library/Logs/CrashReporter"	crash-log dir

5. Path-by-path mapping (and the judgment calls)

Most sites are a clean Local-domain rename. Four deserve an explicit decision rather than a blind rewrite — they're Apple-vestigial or semantically debatable under a BSD+launchd system.

Bare path	→ Proposed	Confidence	Note
/Library/LaunchDaemons	/Local/Library/LaunchDaemons	clean	The Local-domain daemon slot. Core of the change.
/Library/Preferences	/Local/Library/Preferences	clean	Computer/Local prefs domain.
/Library/Preferences/SystemConfiguration	/Local/Library/Preferences/SystemConfiguration	clean	SC store incl. com.apple.Boot.plist.
/Library/Extensions	/Local/Library/Extensions	clean	Auxiliary kext dir (distinct from System /System/Library/Extensions, which stays).
/Library/StartupItems	/Local/Library/StartupItems or drop	decide	Deprecated Apple legacy (pre-launchd). Rename for consistency, or delete the dead bootstrap-create entirely.
/Library/Logs, /Library/Logs/CrashReporter	/Local/Library/Logs, /Local/Library/Logs/CrashReporter	decided	ASL log location. Chosen: /Local/Library/Logs (domain-consistent), not /var/log. Update asl_common.c/.h + the 14 constant (now 20 for "/Local/Library/Logs/").
/Library/Spotlight	leave / inert	n/a	NextBSD has no Spotlight; it's a bundle-path comparison that never matches. Rename only for tidiness.
/Library/Managed Preferences	comment only	n/a	MDM reference in a shim comment; no runtime path.

6. Risk, atomicity & the two strlen constants

• PID 1 launchd_plist_scan.c:265 runs in launchd itself. This is a low-risk edit (the primary daemons live in /System/Library/LaunchDaemons, which is untouched) — but it must be identical in both repos, or the ISO and CI scan different third-party dirs.
• strlen 20 CFXMLPreferencesDomain.c:241 hardcodes 20 == strlen("/Library/Preferences") inline in the strncmp. New string "/Local/Library/Preferences" is 26 — the literal 20 must change to 26 in the same edit or the root-owned-write guard silently misfires.
• strlen 14 asl_common.c:54 defines PATH_LIBRARY_LOGS_LEN 14 (strlen("/Library/Logs/")), consumed by streq_len(…, 14) at :1588. With the decided target "/Local/Library/Logs/" this becomes 20 — change the constant in the same edit.
• no shipped dirs move The overlay ships only /System/Library; no /Library/* directory is shipped. The Local-domain dirs are created lazily at runtime, so there is no image-layout migration — only string edits. This meaningfully shrinks the blast radius vs. the tabled /System move.
• #358 The SCPreferences rename changes where ComputerName persists — coordinate with the open hostname-persistence work so they don't collide.

7. What explicitly stays put

To keep scope honest: nothing under /System/Library changes. That includes the Lever B rtld path /System/Library/Libraries (compat build.yml), kext placement /System/Library/Extensions (pkg, kernel-modules, nextbsd), and the 11 shipped system daemon plists in /System/Library/LaunchDaemons. The Network domain (/Network/Library) and User domain (~/Library) are already conformant and untouched. This plan is only the bare-/Library → /Local/Library slice.

8. How this reconciles with the tabled spike

The layout spike weighed keeping the domains (Option A) vs. moving NextBSD off /System to POSIX (Option B), and noted that bare /Library does not collide with Gershwin. Tabling that decision and doing this instead is a deliberate lean toward Option A's spirit: rather than vacate the Apple shape, make NextBSD rigorously obey gershwin's domain model. Note the trade this accepts: moving into /Local/Library places NextBSD's Local-domain resources in the same domain Gershwin uses for its admin installs — which is what the Local domain is for (shared, this-machine, admin-installed), so it's coherent, but it is the opposite move from the spike's "vacate for clean separation." Worth remembering if the /System question is untabled later.

9. Open decisions

Net Every open decision is closed toward full four-domain consistency: all bare /Library/X → /Local/Library/X, behavioral and cosmetic, in one nextbsd-userland PR that also lands a README location reference. The only path that had a live POSIX alternative and stays POSIX is — none: even ASL logs and the SC store go domain.

10. Appendix: full change surface (file:line, nextbsd-userland/)

All in nextbsd-userland/src (nextbsd/src is being removed, not edited). Behavioral (must edit for correct paths):

src/launchd/src/launchd_plist_scan.c:265      "/Library/LaunchDaemons"
src/launchd/support/launchctl.c:4122          "/Library/StartupItems"
src/libSystemConfiguration/SCPreferences.c:35 PREFS_DEFAULT_DIR "/Library/Preferences/SystemConfiguration"
src/libCoreFoundation/CFKnownLocations.c:38   CFSTR("/Library/Preferences")
src/libCoreFoundation/CFKnownLocations.c:46   CFSTR("/Library/Preferences")
src/libCoreFoundation/CFXMLPreferencesDomain.c:241  strncmp(cpath,"/Library/Preferences",20)   << also 20 -> 26
src/libCoreFoundation/CFBundle_Resources.c:1245     CFSTR("/Library/Spotlight")
src/kext_tools/kext.subproj/bootfiles.h:69    kLibraryExtensionsDir "/Library/Extensions"
src/kext_tools/kext.subproj/bootfiles.h:73    kBootConfig ".../Library/Preferences/SystemConfiguration/com.apple.Boot.plist"
src/kext_tools/kext.subproj/OSKextPrivate.h:57  _kOSKextLibraryExtensionsFolder "/Library/Extensions"
src/syslog/aslcommon/asl_common.c:53          PATH_LIBRARY_LOGS "/Library/Logs/"           << also PATH_LIBRARY_LOGS_LEN 14 (:54)
src/syslog/aslcommon/asl_common.h:32          _PATH_CRASHREPORTER "/Library/Logs/CrashReporter"

Cosmetic (comments / docs / man / help-string / test — update for consistency, no behavior change):

src/launchd/src/launchd_plist_scan.c:7,222,260   src/launchd/src/launchd_plist_scan.h:11
src/launchd/support/launchctl.c:2571             src/launchd/freebsd-shims/NSSystemDirectories.h:6,12
src/libCoreFoundation/CFKnownLocations.c:32      src/libSystemConfiguration/SCDynamicStoreKeys.c:62
src/libSystemConfiguration/SystemConfiguration/SCPreferences.h:93
src/kext_tools/kext.subproj/OSKextPrivate.h:50   src/syslog/aslcommon/asl_common.c:468
src/syslog/freebsd-shims/configuration_profile.h:5
src/hostnamed/hostnameprefset.c:8,112 (help)     src/hostnamed/hostnamed.c:8   src/hostnamed/prefs_monitor.c:6
src/libxpc/xpc/connection.h:96                   src/mDNSResponder/mDNSShared/mDNSResponder.8:100,104
tests/boot-test.sh:1145

Audit method: fresh shallow clones of all 9 nextbsd-redux repos, grep for /Library minus domain-qualified forms, classified behavioral vs cosmetic, scoped to the freebsd-launchd-mach variant. nextbsd↔nextbsd-userland source identity verified by diff; nextbsd/build.sh confirmed to compile src/. freebsd-src excluded from edits by hard rule (upstream fork). Implemented in nextbsd-userland#19.