Clear the onboard phase flags on offboard, and let the mirror signal the owner before revoking the key it signals with

common.sh

@@ -996,6 +996,22 @@ set_state_var() {
     fi
 }
 
+# Removes a key from a flat state file. The inverse of set_state_var, and the reason it exists:
+# onboarding writes HOST*_PHASE*_DONE and nothing took them away again, so a completed offboard
+# left a state file reading INACTIVE beside flags still claiming a finished onboard. Anything
+# reading the flags — the setup checklist, the partnership card — believed the torn-down
+# partnership was live.
+#
+# Absent key is success, not an error: clearing twice is how a re-run after a partial teardown
+# should behave.
+# Usage: clear_state_var "$state_file" "$key"
+clear_state_var() {
+    local file="$1" key="$2"
+    [[ -f "$file" ]] || return 0
+    grep -q "^${key}=" "$file" 2>/dev/null || return 0
+    sed -i "/^${key}=/d" "$file"
+}
+
 # ==============================================================================================
 # ── CONNECTIVITY CHECKS ───────────────────────────────────────────────────────────────────────
 # ==============================================================================================