diff --git a/framework/src/android/net/NetworkScore.java b/framework/src/android/net/NetworkScore.java
index 9786b09..22663e5 100644
--- a/framework/src/android/net/NetworkScore.java
+++ b/framework/src/android/net/NetworkScore.java
@@ -52,11 +52,27 @@
     public static final int KEEP_CONNECTED_FOR_HANDOVER = 1;
 
     // Agent-managed policies
-    // TODO : add them here, starting from 1
+    // This network should lose to a wifi that has ever been validated
+    // NOTE : temporarily this policy is managed by ConnectivityService, because of legacy. The
+    // legacy design has this bit global to the system and tacked on WiFi which means it will affect
+    // networks from carriers who don't want it and non-carrier networks, which is bad for users.
+    // The S design has this on mobile networks only, so this can be fixed eventually ; as CS
+    // doesn't know what carriers need this bit, the initial S implementation will continue to
+    // affect other carriers but will at least leave non-mobile networks alone. Eventually Telephony
+    // should set this on networks from carriers that require it.
     /** @hide */
-    public static final int MIN_AGENT_MANAGED_POLICY = 0;
+    public static final int POLICY_YIELD_TO_BAD_WIFI = 1;
+    // This network is primary for this transport.
     /** @hide */
-    public static final int MAX_AGENT_MANAGED_POLICY = -1;
+    public static final int POLICY_TRANSPORT_PRIMARY = 2;
+    // This network is exiting : it will likely disconnect in a few seconds.
+    /** @hide */
+    public static final int POLICY_EXITING = 3;
+
+    /** @hide */
+    public static final int MIN_AGENT_MANAGED_POLICY = POLICY_YIELD_TO_BAD_WIFI;
+    /** @hide */
+    public static final int MAX_AGENT_MANAGED_POLICY = POLICY_EXITING;
 
     // Bitmask of all the policies applied to this score.
     private final long mPolicies;
@@ -98,6 +114,60 @@
         return 0 != (mPolicies & (1L << policy));
     }
 
+    /**
+     * To the exclusive usage of FullScore
+     * @hide
+     */
+    public long getPolicies() {
+        return mPolicies;
+    }
+
+    /**
+     * Whether this network should yield to a previously validated wifi gone bad.
+     *
+     * If this policy is set, other things being equal, the device will prefer a previously
+     * validated WiFi even if this network is validated and the WiFi is not.
+     * If this policy is not set, the device prefers the validated network.
+     *
+     * @hide
+     */
+    // TODO : Unhide this for telephony and have telephony call it on the relevant carriers.
+    // In the mean time this is handled by Connectivity in a backward-compatible manner.
+    public boolean shouldYieldToBadWifi() {
+        return hasPolicy(POLICY_YIELD_TO_BAD_WIFI);
+    }
+
+    /**
+     * Whether this network is primary for this transport.
+     *
+     * When multiple networks of the same transport are active, the device prefers the ones that
+     * are primary. This is meant in particular for DS-DA devices with a user setting to choose the
+     * default SIM card, or for WiFi STA+STA and make-before-break cases.
+     *
+     * @hide
+     */
+    // TODO : @SystemApi
+    public boolean isTransportPrimary() {
+        return hasPolicy(POLICY_TRANSPORT_PRIMARY);
+    }
+
+    /**
+     * Whether this network is exiting.
+     *
+     * If this policy is set, the device will expect this network to disconnect within seconds.
+     * It will try to migrate to some other network if any is available, policy permitting, to
+     * avoid service disruption.
+     * This is useful in particular when a good cellular network is available and WiFi is getting
+     * weak and risks disconnecting soon. The WiFi network should be marked as exiting so that
+     * the device will prefer the reliable mobile network over this soon-to-be-lost WiFi.
+     *
+     * @hide
+     */
+    // TODO : @SystemApi
+    public boolean isExiting() {
+        return hasPolicy(POLICY_EXITING);
+    }
+
     @Override
     public String toString() {
         return "Score(" + mLegacyInt + ")";
@@ -137,6 +207,7 @@
         private static final int INVALID_LEGACY_INT = Integer.MIN_VALUE;
         private int mLegacyInt = INVALID_LEGACY_INT;
         private int mKeepConnectedReason = KEEP_CONNECTED_NONE;
+        private int mPolicies = 0;
 
         /**
          * Sets the legacy int for this score.
@@ -152,6 +223,75 @@
             return this;
         }
 
+
+        /**
+         * Set for a network that should never be preferred to a wifi that has ever been validated
+         *
+         * If this policy is set, other things being equal, the device will prefer a previously
+         * validated WiFi even if this network is validated and the WiFi is not.
+         * If this policy is not set, the device prefers the validated network.
+         *
+         * @return this builder
+         * @hide
+         */
+        // TODO : Unhide this for telephony and have telephony call it on the relevant carriers.
+        // In the mean time this is handled by Connectivity in a backward-compatible manner.
+        @NonNull
+        public Builder setShouldYieldToBadWifi(final boolean val) {
+            if (val) {
+                mPolicies |= (1L << POLICY_YIELD_TO_BAD_WIFI);
+            } else {
+                mPolicies &= ~(1L << POLICY_YIELD_TO_BAD_WIFI);
+            }
+            return this;
+        }
+
+        /**
+         * Set for a network that is primary for this transport.
+         *
+         * When multiple networks of the same transport are active, the device prefers the ones that
+         * are primary. This is meant in particular for DS-DA devices with a user setting to choose
+         * the default SIM card, or for WiFi STA+STA and make-before-break cases.
+         *
+         * @return this builder
+         * @hide
+         */
+        // TODO : @SystemApi
+        @NonNull
+        public Builder setTransportPrimary(final boolean val) {
+            if (val) {
+                mPolicies |= (1L << POLICY_TRANSPORT_PRIMARY);
+            } else {
+                mPolicies &= ~(1L << POLICY_TRANSPORT_PRIMARY);
+            }
+            return this;
+        }
+
+        /**
+         * Set for a network that will likely disconnect in a few seconds.
+         *
+         * If this policy is set, the device will expect this network to disconnect within seconds.
+         * It will try to migrate to some other network if any is available, policy permitting, to
+         * avoid service disruption.
+         * This is useful in particular when a good cellular network is available and WiFi is
+         * getting weak and risks disconnecting soon. The WiFi network should be marked as exiting
+         * so that the device will prefer the reliable mobile network over this soon-to-be-lost
+         * WiFi.
+         *
+         * @return this builder
+         * @hide
+         */
+        // TODO : @SystemApi
+        @NonNull
+        public Builder setExiting(final boolean val) {
+            if (val) {
+                mPolicies |= (1L << POLICY_EXITING);
+            } else {
+                mPolicies &= ~(1L << POLICY_EXITING);
+            }
+            return this;
+        }
+
         /**
          * Set the keep-connected reason.
          *
@@ -169,7 +309,7 @@
          */
         @NonNull
         public NetworkScore build() {
-            return new NetworkScore(mLegacyInt, POLICY_NONE, mKeepConnectedReason);
+            return new NetworkScore(mLegacyInt, mPolicies, mKeepConnectedReason);
         }
     }
 }
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index ca01c8e..d6b0bcc 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -1324,7 +1324,7 @@
         mLingerMonitor = new LingerMonitor(mContext, mNotifier, dailyLimit, rateLimit);
 
         mMultinetworkPolicyTracker = mDeps.makeMultinetworkPolicyTracker(
-                mContext, mHandler, () -> rematchForAvoidBadWifiUpdate());
+                mContext, mHandler, () -> updateAvoidBadWifi());
         mMultinetworkPolicyTracker.start();
 
         mDnsManager = new DnsManager(mContext, mDnsResolver);
@@ -4370,8 +4370,10 @@
         return avoidBadWifi();
     }
 
-    // TODO : this function is now useless.
-    private void rematchForAvoidBadWifiUpdate() {
+    private void updateAvoidBadWifi() {
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            nai.updateScoreForNetworkAgentConfigUpdate();
+        }
         rematchAllNetworksAndRequests();
     }
 
diff --git a/services/core/java/com/android/server/connectivity/FullScore.java b/services/core/java/com/android/server/connectivity/FullScore.java
index 375d005..117253f 100644
--- a/services/core/java/com/android/server/connectivity/FullScore.java
+++ b/services/core/java/com/android/server/connectivity/FullScore.java
@@ -17,9 +17,13 @@
 package com.android.server.connectivity;
 
 import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_METERED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
 import static android.net.NetworkCapabilities.TRANSPORT_VPN;
 import static android.net.NetworkScore.KEEP_CONNECTED_NONE;
+import static android.net.NetworkScore.POLICY_EXITING;
+import static android.net.NetworkScore.POLICY_TRANSPORT_PRIMARY;
+import static android.net.NetworkScore.POLICY_YIELD_TO_BAD_WIFI;
 
 import android.annotation.IntDef;
 import android.annotation.NonNull;
@@ -52,7 +56,8 @@
             POLICY_IS_VALIDATED,
             POLICY_IS_VPN,
             POLICY_EVER_USER_SELECTED,
-            POLICY_ACCEPT_UNVALIDATED
+            POLICY_ACCEPT_UNVALIDATED,
+            POLICY_IS_UNMETERED
     })
     public @interface Policy {
     }
@@ -77,12 +82,22 @@
     /** @hide */
     public static final int POLICY_ACCEPT_UNVALIDATED = 60;
 
+    // This network is unmetered. {@see NetworkCapabilities.NET_CAPABILITY_NOT_METERED}.
+    /** @hide */
+    public static final int POLICY_IS_UNMETERED = 59;
+
     // To help iterate when printing
     @VisibleForTesting
-    static final int MIN_CS_MANAGED_POLICY = POLICY_ACCEPT_UNVALIDATED;
+    static final int MIN_CS_MANAGED_POLICY = POLICY_IS_UNMETERED;
     @VisibleForTesting
     static final int MAX_CS_MANAGED_POLICY = POLICY_IS_VALIDATED;
 
+    // Mask for policies in NetworkScore. This should have all bits managed by NetworkScore set
+    // and all bits managed by FullScore unset. As bits are handled from 0 up in NetworkScore and
+    // from 63 down in FullScore, cut at the 32rd bit for simplicity, but change this if some day
+    // there are more than 32 bits handled on either side.
+    private static final int EXTERNAL_POLICIES_MASK = 0x0000FFFF;
+
     @VisibleForTesting
     static @NonNull String policyNameOf(final int policy) {
         switch (policy) {
@@ -90,6 +105,10 @@
             case POLICY_IS_VPN: return "IS_VPN";
             case POLICY_EVER_USER_SELECTED: return "EVER_USER_SELECTED";
             case POLICY_ACCEPT_UNVALIDATED: return "ACCEPT_UNVALIDATED";
+            case POLICY_IS_UNMETERED: return "IS_UNMETERED";
+            case POLICY_YIELD_TO_BAD_WIFI: return "YIELD_TO_BAD_WIFI";
+            case POLICY_TRANSPORT_PRIMARY: return "TRANSPORT_PRIMARY";
+            case POLICY_EXITING: return "EXITING";
         }
         throw new IllegalArgumentException("Unknown policy : " + policy);
     }
@@ -112,15 +131,23 @@
      * @param score the score supplied by the agent
      * @param caps the NetworkCapabilities of the network
      * @param config the NetworkAgentConfig of the network
-     * @return an FullScore that is appropriate to use for ranking.
+     * @param yieldToBadWiFi whether this network yields to a previously validated wifi gone bad
+     * @return a FullScore that is appropriate to use for ranking.
      */
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
     public static FullScore fromNetworkScore(@NonNull final NetworkScore score,
-            @NonNull final NetworkCapabilities caps, @NonNull final NetworkAgentConfig config) {
-        return withPolicies(score.getLegacyInt(), score.getKeepConnectedReason(),
+            @NonNull final NetworkCapabilities caps, @NonNull final NetworkAgentConfig config,
+            final boolean yieldToBadWiFi) {
+        return withPolicies(score.getLegacyInt(), score.getPolicies(),
+                score.getKeepConnectedReason(),
                 caps.hasCapability(NET_CAPABILITY_VALIDATED),
                 caps.hasTransport(TRANSPORT_VPN),
+                caps.hasCapability(NET_CAPABILITY_NOT_METERED),
                 config.explicitlySelected,
-                config.acceptUnvalidated);
+                config.acceptUnvalidated,
+                yieldToBadWiFi);
     }
 
     /**
@@ -142,12 +169,17 @@
         final boolean mayValidate = caps.hasCapability(NET_CAPABILITY_INTERNET);
         // VPN transports are known in advance.
         final boolean vpn = caps.hasTransport(TRANSPORT_VPN);
+        // Prospective scores are always unmetered, because unmetered networks are stronger
+        // than metered networks, and it's not known in advance whether the network is metered.
+        final boolean unmetered = true;
         // The network hasn't been chosen by the user (yet, at least).
         final boolean everUserSelected = false;
         // Don't assume the user will accept unvalidated connectivity.
         final boolean acceptUnvalidated = false;
-        return withPolicies(score.getLegacyInt(), KEEP_CONNECTED_NONE,
-                mayValidate, vpn, everUserSelected, acceptUnvalidated);
+        // Don't assume clinging to bad wifi
+        final boolean yieldToBadWiFi = false;
+        return withPolicies(score.getLegacyInt(), score.getPolicies(), KEEP_CONNECTED_NONE,
+                mayValidate, vpn, unmetered, everUserSelected, acceptUnvalidated, yieldToBadWiFi);
     }
 
     /**
@@ -157,26 +189,39 @@
      * @param config the NetworkAgentConfig of the network
      * @return a score with the policies from the arguments reset
      */
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
     public FullScore mixInScore(@NonNull final NetworkCapabilities caps,
-            @NonNull final NetworkAgentConfig config) {
-        return withPolicies(mLegacyInt, mKeepConnectedReason,
+            @NonNull final NetworkAgentConfig config, final boolean avoidBadWiFi) {
+        return withPolicies(mLegacyInt, mPolicies, mKeepConnectedReason,
                 caps.hasCapability(NET_CAPABILITY_VALIDATED),
                 caps.hasTransport(TRANSPORT_VPN),
+                caps.hasCapability(NET_CAPABILITY_NOT_METERED),
                 config.explicitlySelected,
-                config.acceptUnvalidated);
+                config.acceptUnvalidated,
+                avoidBadWiFi);
     }
 
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
     private static FullScore withPolicies(@NonNull final int legacyInt,
+            final long externalPolicies,
             @KeepConnectedReason final int keepConnectedReason,
             final boolean isValidated,
             final boolean isVpn,
+            final boolean isUnmetered,
             final boolean everUserSelected,
-            final boolean acceptUnvalidated) {
-        return new FullScore(legacyInt,
-                (isValidated         ? 1L << POLICY_IS_VALIDATED : 0)
+            final boolean acceptUnvalidated,
+            final boolean yieldToBadWiFi) {
+        return new FullScore(legacyInt, (externalPolicies & EXTERNAL_POLICIES_MASK)
+                | (isValidated       ? 1L << POLICY_IS_VALIDATED : 0)
                 | (isVpn             ? 1L << POLICY_IS_VPN : 0)
+                | (isUnmetered       ? 1L << POLICY_IS_UNMETERED : 0)
                 | (everUserSelected  ? 1L << POLICY_EVER_USER_SELECTED : 0)
-                | (acceptUnvalidated ? 1L << POLICY_ACCEPT_UNVALIDATED : 0),
+                | (acceptUnvalidated ? 1L << POLICY_ACCEPT_UNVALIDATED : 0)
+                | (yieldToBadWiFi    ? 1L << POLICY_YIELD_TO_BAD_WIFI : 0),
                 keepConnectedReason);
     }
 
diff --git a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
index d16a2de..3902573 100644
--- a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
@@ -17,6 +17,7 @@
 package com.android.server.connectivity;
 
 import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport;
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 import static android.net.NetworkCapabilities.transportNamesOf;
 
 import android.annotation.NonNull;
@@ -362,9 +363,9 @@
         linkProperties = lp;
         networkCapabilities = nc;
         networkAgentConfig = config;
-        setScore(score); // uses members networkCapabilities and networkAgentConfig
-        clatd = new Nat464Xlat(this, netd, dnsResolver, deps);
         mConnService = connService;
+        setScore(score); // uses members connService, networkCapabilities and networkAgentConfig
+        clatd = new Nat464Xlat(this, netd, dnsResolver, deps);
         mContext = context;
         mHandler = handler;
         this.factorySerialNumber = factorySerialNumber;
@@ -706,7 +707,7 @@
             @NonNull final NetworkCapabilities nc) {
         final NetworkCapabilities oldNc = networkCapabilities;
         networkCapabilities = nc;
-        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig);
+        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig, yieldToBadWiFi());
         final NetworkMonitorManager nm = mNetworkMonitor;
         if (nm != null) {
             nm.notifyNetworkCapabilitiesChanged(nc);
@@ -714,6 +715,11 @@
         return oldNc;
     }
 
+    private boolean yieldToBadWiFi() {
+        // Only cellular networks yield to bad wifi
+        return networkCapabilities.hasTransport(TRANSPORT_CELLULAR) && !mConnService.avoidBadWifi();
+    }
+
     public ConnectivityService connService() {
         return mConnService;
     }
@@ -884,15 +890,6 @@
         return isVPN();
     }
 
-    // Return true on devices configured to ignore score penalty for wifi networks
-    // that become unvalidated (b/31075769).
-    private boolean ignoreWifiUnvalidationPenalty() {
-        boolean isWifi = networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) &&
-                networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
-        boolean avoidBadWifi = mConnService.avoidBadWifi() || avoidUnvalidated;
-        return isWifi && !avoidBadWifi && everValidated;
-    }
-
     public FullScore getScore() {
         return mScore;
     }
@@ -913,7 +910,8 @@
      * Mix-in the ConnectivityService-managed bits in the score.
      */
     public void setScore(final NetworkScore score) {
-        mScore = FullScore.fromNetworkScore(score, networkCapabilities, networkAgentConfig);
+        mScore = FullScore.fromNetworkScore(score, networkCapabilities, networkAgentConfig,
+                yieldToBadWiFi());
     }
 
     /**
@@ -922,7 +920,7 @@
      * Call this after updating the network agent config.
      */
     public void updateScoreForNetworkAgentConfigUpdate() {
-        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig);
+        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig, yieldToBadWiFi());
     }
 
     /**
@@ -1085,7 +1083,7 @@
         return "NetworkAgentInfo{"
                 + "network{" + network + "}  handle{" + network.getNetworkHandle() + "}  ni{"
                 + networkInfo.toShortString() + "} "
-                + "  Score{" + getCurrentScore() + "} "
+                + mScore + " "
                 + (isNascent() ? " nascent" : (isLingering() ? " lingering" : ""))
                 + (everValidated ? " everValidated" : "")
                 + (lastValidated ? " lastValidated" : "")
diff --git a/tests/net/java/com/android/server/connectivity/FullScoreTest.kt b/tests/net/java/com/android/server/connectivity/FullScoreTest.kt
index 2864bc7..f0d7d86 100644
--- a/tests/net/java/com/android/server/connectivity/FullScoreTest.kt
+++ b/tests/net/java/com/android/server/connectivity/FullScoreTest.kt
@@ -56,7 +56,7 @@
             if (vpn) addTransportType(NetworkCapabilities.TRANSPORT_VPN)
             if (validated) addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
         }.build()
-        return mixInScore(nc, nac)
+        return mixInScore(nc, nac, false /* avoidBadWifi */)
     }
 
     @Test