Explicit host config outranks the local build-host inference; document it

The published-db marker also exists on any workstation that once ran a full
local release, so --host / OMARCHY_REPO_HOST / .repo-host are now checked
before on_repo_host everywhere (triggers, advances, doctor). README documents
the detection, the caveat, and the .repo-host tie-breaker.

README.md

@@ -493,6 +493,16 @@ root@pkgs.example.com
 
 All connections are plain ssh; nothing else is used to reach the host.
 
+**How "this machine is the build host" is detected — and its one caveat.**
+The marker is the published database living in this checkout
+(`pkgs.omarchy.org/<channel>/<arch>/omarchy.db*`), the same convention the
+rest of `bin/` uses. A workstation that once ran a full local
+`bin/repo release` carries that marker too and would infer it is the host.
+An explicitly configured destination always outranks the inference — `--host`,
+`OMARCHY_REPO_HOST`, and `.repo-host` are checked first, and only when none is
+set does local detection apply. So if a machine ever misidentifies itself,
+writing the real host into `.repo-host` is the fix.
+
 ## Directory Structure
 
 ```

bin/omarchy-pkgs

@@ -323,7 +323,9 @@ regenerate_checksums() {
 
 trigger_build_host() {
   local host
-  if on_repo_host; then
+  # Explicit host configuration outranks the local-host inference (a
+  # workstation that ran a full local release carries the db marker too).
+  if ! resolve_repo_host "${REPO_HOST_OVERRIDE:-}" >/dev/null && on_repo_host; then
     print_info "Triggering edge build locally (this is the build host)..."
     if mkdir -p "${OMARCHY_STATE_DIR:-/root/.state}" &&
       touch "${OMARCHY_STATE_DIR:-/root/.state}/.sync-needed-edge" &&

bin/omarchy-release

@@ -241,14 +241,17 @@ touch /root/.state/.sync-needed-rc
 systemctl start --no-block omarchy-auto-release-rc.service
 '
 
+# An explicitly configured destination outranks the local-host inference: a
+# workstation that once ran a full local release carries the published-db
+# marker too, and its .repo-host must still win.
 trigger_rc_build() {
   local host
-  if on_repo_host; then
-    print_info "Triggering rc build locally (this is the build host)..."
-    bash -c "$RC_TRIGGER_SCRIPT"
-  elif host=$(repo_host); then
+  if host=$(repo_host); then
     print_info "Triggering rc build on $host..."
     ssh "$host" "$RC_TRIGGER_SCRIPT"
+  elif on_repo_host; then
+    print_info "Triggering rc build locally (this is the build host)..."
+    bash -c "$RC_TRIGGER_SCRIPT"
   else
     print_no_host_help "build the rc channel" "$RC_TRIGGER_SCRIPT"
     return 1
@@ -259,14 +262,14 @@ host_advance() { # host_advance <from> <to> [extra args...]
   local from="$1" to="$2"
   shift 2
   local host
-  if on_repo_host; then
+  if host=$(repo_host); then
+    print_info "Advancing $from -> $to on $host..."
+    ssh "$host" "cd /root/omarchy-pkgs && git pull --ff-only && bin/repo advance --from $from --to $to --skip-prod-check $*"
+  elif on_repo_host; then
     # This checkout holds the published tree — advance right here, from this
     # checkout's tooling (no pull: the operator controls their working copy).
     print_info "Advancing $from -> $to locally (this is the build host)..."
     "$BUILD_ROOT/bin/repo" advance --from "$from" --to "$to" --skip-prod-check "$@"
-  elif host=$(repo_host); then
-    print_info "Advancing $from -> $to on $host..."
-    ssh "$host" "cd /root/omarchy-pkgs && git pull --ff-only && bin/repo advance --from $from --to $to --skip-prod-check $*"
   else
     print_no_host_help "advance $from -> $to" \
       "  cd /root/omarchy-pkgs && bin/repo advance --from $from --to $to --skip-prod-check $*"
@@ -960,10 +963,10 @@ cmd_doctor() {
     print_warning "rc channel db not readable — bootstrap it first: bin/repo bootstrap-rc (on the build host)"
   fi
   local host
-  if on_repo_host; then
-    print_success "this machine IS the build host — host operations run locally"
-  elif host=$(repo_host); then
+  if host=$(repo_host); then
     check "build host ssh ($host)" ssh -o ConnectTimeout=10 "$host" true
+  elif on_repo_host; then
+    print_success "this machine IS the build host — host operations run locally"
   else
     print_warning "no build host configured — set OMARCHY_REPO_HOST, --host, or write an ssh destination (root@<host> or an ssh-config alias) to $BUILD_ROOT/.repo-host; until then builds trigger on the 6h timer only"
   fi