feat(core): harden saved-device control plane against hostile peers

Bound pending offers, enforce pre-approval limits and max_saved_devices,
add per-identity cooldowns, silently reject invalid traffic, and redact
sensitive values from production events and errors without inventing
accepted-transfer quotas.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/vnidrop/src/api.rs

@@ -288,10 +288,22 @@ pub struct CoreLimits {
     pub max_metadata_bytes: u64,
     pub max_events: u64,
     pub max_pending_approvals: u64,
-    /// Incoming pairing offers awaiting the local user's decision.
+    /// Incoming pairing / targeted offers awaiting the local user's decision.
     pub max_pending_offers: u64,
     pub max_concurrent_transfers: u64,
     pub event_queue_capacity: u64,
+    /// Cap on Saved + pending mutual-consent relationships (design §14).
+    pub max_saved_devices: u64,
+    /// Quiet period after a decline or repeated malformed control-plane traffic.
+    pub identity_cooldown_ms: u64,
+    /// Malformed control-plane messages from one identity before cooldown.
+    pub malformed_strike_limit: u64,
+    /// Pairing RPC / acknowledgement wait bound (milliseconds).
+    pub pairing_timeout_ms: u64,
+    /// Pre-approval offer decision wait bound (milliseconds).
+    pub offer_timeout_ms: u64,
+    /// Connection establishment bound for targeted transfers (milliseconds).
+    pub connection_timeout_ms: u64,
 }
 
 impl Default for CoreLimits {
@@ -313,6 +325,12 @@ impl Default for CoreLimits {
             max_pending_offers: 16,
             max_concurrent_transfers: 8,
             event_queue_capacity: 1_024,
+            max_saved_devices: 256,
+            identity_cooldown_ms: 60_000,
+            malformed_strike_limit: 5,
+            pairing_timeout_ms: 15_000,
+            offer_timeout_ms: 120_000,
+            connection_timeout_ms: 30_000,
         }
     }
 }
@@ -331,6 +349,12 @@ impl CoreLimits {
             ("max_pending_offers", self.max_pending_offers),
             ("max_concurrent_transfers", self.max_concurrent_transfers),
             ("event_queue_capacity", self.event_queue_capacity),
+            ("max_saved_devices", self.max_saved_devices),
+            ("identity_cooldown_ms", self.identity_cooldown_ms),
+            ("malformed_strike_limit", self.malformed_strike_limit),
+            ("pairing_timeout_ms", self.pairing_timeout_ms),
+            ("offer_timeout_ms", self.offer_timeout_ms),
+            ("connection_timeout_ms", self.connection_timeout_ms),
         ];
         for (name, value) in positive {
             if value == 0 {
@@ -342,6 +366,8 @@ impl CoreLimits {
             ("max_pending_offers", self.max_pending_offers),
             ("max_concurrent_transfers", self.max_concurrent_transfers),
             ("event_queue_capacity", self.event_queue_capacity),
+            ("max_saved_devices", self.max_saved_devices),
+            ("malformed_strike_limit", self.malformed_strike_limit),
         ] {
             usize::try_from(value)
                 .with_context(|| format!("core limit {name} exceeds platform capacity"))?;

crates/vnidrop/src/control_plane.rs

@@ -0,0 +1,280 @@
+//! Saved-device control-plane hardening (design §14).
+//!
+//! Bounds hostile / noisy peers without imposing quotas on transfers the
+//! receiver has already accepted.
+
+use std::{
+    collections::HashMap,
+    sync::{Arc, Mutex},
+};
+
+use data_encoding::HEXLOWER;
+use serde_json::{Map, Value};
+
+use crate::util::now_ms;
+
+/// Per-identity quiet period after declines or repeated malformed traffic.
+#[derive(Clone)]
+pub(crate) struct IdentityCooldown {
+    inner: Arc<Mutex<CooldownInner>>,
+    cooldown_ms: i64,
+    strike_limit: u32,
+}
+
+#[derive(Default)]
+struct CooldownInner {
+    until: HashMap<String, i64>,
+    strikes: HashMap<String, u32>,
+}
+
+impl IdentityCooldown {
+    pub(crate) fn new(cooldown_ms: u64, strike_limit: u64) -> Self {
+        Self {
+            inner: Arc::new(Mutex::new(CooldownInner::default())),
+            cooldown_ms: cooldown_ms as i64,
+            strike_limit: strike_limit as u32,
+        }
+    }
+
+    pub(crate) fn is_cooling(&self, identity: &str) -> bool {
+        let now = now_ms();
+        let mut state = self
+            .inner
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        state.until.retain(|_, until| *until > now);
+        state.until.contains_key(identity)
+    }
+
+    pub(crate) fn record_decline(&self, identity: &str) {
+        let until = now_ms() + self.cooldown_ms;
+        let mut state = self
+            .inner
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        state.until.insert(identity.to_string(), until);
+        state.strikes.remove(identity);
+    }
+
+    /// Count a malformed / spoofed / ineligible control-plane message.
+    ///
+    /// Trips cooldown once the strike limit is reached. Returns whether the
+    /// identity is now cooling (including an already-active cooldown).
+    pub(crate) fn record_malformed(&self, identity: &str) -> bool {
+        if self.is_cooling(identity) {
+            return true;
+        }
+        let mut state = self
+            .inner
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        let strikes = state.strikes.entry(identity.to_string()).or_insert(0);
+        *strikes = strikes.saturating_add(1);
+        if *strikes >= self.strike_limit {
+            state
+                .until
+                .insert(identity.to_string(), now_ms() + self.cooldown_ms);
+            state.strikes.remove(identity);
+            return true;
+        }
+        false
+    }
+
+    pub(crate) fn clear_strikes(&self, identity: &str) {
+        let mut state = self
+            .inner
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        state.strikes.remove(identity);
+    }
+}
+
+const REDACTED: &str = "[redacted]";
+
+/// Keys whose values must never appear in production events / diagnostics.
+fn is_sensitive_key(key: &str) -> bool {
+    matches!(
+        key,
+        "endpoint_id"
+            | "peer_endpoint_id"
+            | "sender_endpoint_id"
+            | "receiver_endpoint_id"
+            | "from_endpoint_id"
+            | "remote_endpoint_id"
+            | "local_endpoint_id"
+            | "ticket"
+            | "blob_ticket"
+            | "authorization"
+            | "capability"
+            | "secret"
+            | "grant"
+            | "grant_id"
+            | "proof"
+            | "mac"
+            | "filename"
+            | "file_name"
+            | "path"
+            | "display_name"
+            | "transfer_name"
+            | "sender_display_name"
+            | "remote_display_name"
+            | "address"
+            | "addrs"
+            | "relay_url"
+            | "relay_urls"
+    )
+}
+
+/// Stable fingerprint so diagnostics can correlate without leaking raw values.
+pub(crate) fn fingerprint(value: &str) -> String {
+    let digest = blake3::hash(value.as_bytes());
+    let hex = HEXLOWER.encode(digest.as_bytes());
+    format!("<redacted:{}>", &hex[..8])
+}
+
+pub(crate) fn redact_json(value: Value) -> Value {
+    match value {
+        Value::Object(map) => Value::Object(redact_object(map)),
+        Value::Array(items) => Value::Array(items.into_iter().map(redact_json).collect()),
+        other => other,
+    }
+}
+
+fn redact_object(map: Map<String, Value>) -> Map<String, Value> {
+    map.into_iter()
+        .map(|(key, value)| {
+            if is_sensitive_key(&key) {
+                let redacted = match value {
+                    Value::String(raw) if !raw.is_empty() => Value::String(fingerprint(&raw)),
+                    Value::Null => Value::Null,
+                    _ => Value::String(REDACTED.to_string()),
+                };
+                (key, redacted)
+            } else {
+                (key, redact_json(value))
+            }
+        })
+        .collect()
+}
+
+/// Scrub ticket-like and long opaque blobs from free-form error / log text.
+pub(crate) fn redact_text(input: &str) -> String {
+    let mut out = String::with_capacity(input.len());
+    let mut rest = input;
+    while let Some(idx) = rest.find("vnd1:") {
+        out.push_str(&rest[..idx]);
+        out.push_str(REDACTED);
+        rest = &rest[idx + 5..];
+        // Skip the remainder of the ticket token (non-whitespace).
+        let end = rest
+            .find(|c: char| c.is_whitespace() || c == '"' || c == '\'')
+            .unwrap_or(rest.len());
+        rest = &rest[end..];
+    }
+    out.push_str(rest);
+    // Collapse long hex runs that look like endpoint ids / grant material.
+    collapse_long_hex(&out)
+}
+
+fn collapse_long_hex(input: &str) -> String {
+    let mut out = String::with_capacity(input.len());
+    let bytes = input.as_bytes();
+    let mut i = 0;
+    while i < bytes.len() {
+        if bytes[i].is_ascii_hexdigit() {
+            let start = i;
+            while i < bytes.len() && bytes[i].is_ascii_hexdigit() {
+                i += 1;
+            }
+            let len = i - start;
+            if len >= 32 {
+                out.push_str(REDACTED);
+            } else {
+                out.push_str(&input[start..i]);
+            }
+        } else {
+            out.push(bytes[i] as char);
+            i += 1;
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    /// Documented non-enforcement: accepted transfers have no per-device quota.
+    const ACCEPTED_TRANSFER_QUOTA_FIELDS: &[&str] = &[
+        "max_per_device_files",
+        "max_per_device_bytes",
+        "max_per_device_bandwidth",
+        "max_per_device_transfers",
+    ];
+
+    #[test]
+    fn cooldown_trips_after_strike_limit_and_isolates_identities() {
+        let guard = IdentityCooldown::new(60_000, 3);
+        assert!(!guard.record_malformed("a"));
+        assert!(!guard.record_malformed("a"));
+        assert!(guard.record_malformed("a"));
+        assert!(guard.is_cooling("a"));
+        assert!(!guard.is_cooling("b"));
+        guard.record_decline("b");
+        assert!(guard.is_cooling("b"));
+        assert!(guard.is_cooling("a"));
+    }
+
+    #[test]
+    fn redaction_scrubs_sensitive_event_fields() {
+        let raw = json!({
+            "transfer_id": "ok-to-keep",
+            "sender_endpoint_id": "abc123endpointid000000000000000000000000000000000000000000000000",
+            "transfer_name": "secret.pdf",
+            "ticket": "vnd1:deadbeef",
+            "file_count": 2,
+            "nested": { "capability": [1, 2, 3], "state": "saved" }
+        });
+        let redacted = redact_json(raw);
+        let obj = redacted.as_object().unwrap();
+        assert_eq!(obj.get("transfer_id").unwrap(), "ok-to-keep");
+        assert_eq!(obj.get("file_count").unwrap(), 2);
+        let sender = obj.get("sender_endpoint_id").unwrap().as_str().unwrap();
+        assert!(sender.starts_with("<redacted:"));
+        assert!(!sender.contains("abc123"));
+        let name = obj.get("transfer_name").unwrap().as_str().unwrap();
+        assert!(name.starts_with("<redacted:"));
+        assert!(!name.contains("secret"));
+        assert!(obj
+            .get("ticket")
+            .unwrap()
+            .as_str()
+            .unwrap()
+            .starts_with("<redacted:"));
+        let nested = obj.get("nested").unwrap().as_object().unwrap();
+        assert_eq!(nested.get("capability").unwrap(), REDACTED);
+        assert_eq!(nested.get("state").unwrap(), "saved");
+    }
+
+    #[test]
+    fn redact_text_strips_tickets_and_long_hex() {
+        let text = "ticket vnd1:abcDEF123 and id 0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+        let scrubbed = redact_text(text);
+        assert!(!scrubbed.contains("vnd1:"));
+        assert!(!scrubbed.contains("0123456789abcdef"));
+        assert!(scrubbed.contains(REDACTED));
+    }
+
+    #[test]
+    fn accepted_transfer_quota_fields_are_not_core_limits() {
+        // Control-plane hardening must not invent per-device accepted-transfer quotas.
+        let encoded = serde_json::to_string(&crate::api::CoreLimits::default()).unwrap();
+        for field in ACCEPTED_TRANSFER_QUOTA_FIELDS {
+            assert!(
+                !encoded.contains(field),
+                "CoreLimits must not enforce {field}"
+            );
+        }
+    }
+}

crates/vnidrop/src/device_relationship/mod.rs

@@ -46,7 +46,6 @@ use crypto::{
 };
 
 const PENDING_TTL_MS: i64 = 30 * 60 * 1_000;
-const PAIRING_RPC_TIMEOUT: Duration = Duration::from_secs(15);
 
 #[derive(Clone)]
 pub(crate) struct DeviceRelationshipService {
@@ -58,6 +57,8 @@ pub(crate) struct DeviceRelationshipService {
     endpoint: Endpoint,
     relay_mode: CoreRelayMode,
     custom_relay_urls: Vec<RelayUrl>,
+    max_saved_devices: u64,
+    pairing_timeout: Duration,
     peer_locks: Arc<TokioMutex<HashMap<String, Arc<TokioMutex<()>>>>>,
 }
 
@@ -75,6 +76,8 @@ impl DeviceRelationshipService {
         endpoint: Endpoint,
         relay_mode: CoreRelayMode,
         custom_relay_urls: Vec<RelayUrl>,
+        max_saved_devices: u64,
+        pairing_timeout_ms: u64,
     ) -> Self {
         Self {
             pool,
@@ -85,10 +88,36 @@ impl DeviceRelationshipService {
             endpoint,
             relay_mode,
             custom_relay_urls,
+            max_saved_devices,
+            pairing_timeout: Duration::from_millis(pairing_timeout_ms),
             peer_locks: Arc::new(TokioMutex::new(HashMap::new())),
         }
     }
 
+    /// Slots consumed by Saved or in-flight mutual-consent relationships.
+    async fn relationship_slots_used(&self) -> Result<u64, VnidropError> {
+        let row = sqlx::query(
+            r#"
+            SELECT COUNT(*) AS n FROM device_relationships
+            WHERE state IN ('saved', 'pending_outgoing', 'pending_incoming')
+            "#,
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(VnidropError::repository)?;
+        Ok(row.get::<i64, _>("n") as u64)
+    }
+
+    async fn can_create_new_relationship(
+        &self,
+        peer_endpoint_id: &str,
+    ) -> Result<bool, VnidropError> {
+        if self.find_row(peer_endpoint_id).await?.is_some() {
+            return Ok(true);
+        }
+        Ok(self.relationship_slots_used().await? < self.max_saved_devices)
+    }
+
     pub(super) async fn lock_peer(&self, peer_endpoint_id: &str) -> Arc<TokioMutex<()>> {
         let mut locks = self.peer_locks.lock().await;
         locks
@@ -254,6 +283,10 @@ impl DeviceRelationshipService {
             }
         }
 
+        if !self.can_create_new_relationship(&peer_endpoint_id).await? {
+            return Ok(false);
+        }
+
         let Some(taken) = self.eligibility.take_eligibility(&peer_endpoint_id).await? else {
             return Ok(false);
         };
@@ -316,7 +349,7 @@ impl DeviceRelationshipService {
         let addr = self.peer_addr(&peer_endpoint_id).await?;
         let client = RelationshipClient::connect(self.endpoint.clone(), addr);
         let response = match tokio::time::timeout(
-            PAIRING_RPC_TIMEOUT,
+            self.pairing_timeout,
             client.pairing_request(PairingRequest {
                 session_id: taken.session_id.clone(),
                 capability: taken.capability.to_vec(),
@@ -382,7 +415,7 @@ impl DeviceRelationshipService {
             let addr = self.peer_addr(&peer_endpoint_id).await?;
             let client = RelationshipClient::connect(self.endpoint.clone(), addr);
             let _ = tokio::time::timeout(
-                PAIRING_RPC_TIMEOUT,
+                self.pairing_timeout,
                 client.pairing_consent(PairingConsent {
                     accepted: false,
                     grant: None,
@@ -413,7 +446,7 @@ impl DeviceRelationshipService {
         let addr = self.peer_addr(&peer_endpoint_id).await?;
         let client = RelationshipClient::connect(self.endpoint.clone(), addr);
         let response = match tokio::time::timeout(
-            PAIRING_RPC_TIMEOUT,
+            self.pairing_timeout,
             client.pairing_consent(PairingConsent {
                 accepted: true,
                 grant: Some(grant.clone()),
@@ -456,7 +489,7 @@ impl DeviceRelationshipService {
                     )
                     .await?;
                 match tokio::time::timeout(
-                    PAIRING_RPC_TIMEOUT,
+                    self.pairing_timeout,
                     client.pairing_ack(PairingAck {
                         possession_proof: proof,
                         challenge: ack_challenge.encode(),
@@ -542,6 +575,11 @@ impl DeviceRelationshipService {
             return PairingRequestResponse::Rejected;
         }
 
+        match self.can_create_new_relationship(&remote_endpoint_id).await {
+            Ok(true) => {}
+            Ok(false) | Err(_) => return PairingRequestResponse::Rejected,
+        }
+
         let now = now_ms();
         if self
             .upsert_relationship(RelationshipUpsert {
@@ -726,7 +764,7 @@ impl DeviceRelationshipService {
         let addr = self.peer_addr(peer_endpoint_id).await?;
         let client = RelationshipClient::connect(self.endpoint.clone(), addr);
         let response = match tokio::time::timeout(
-            PAIRING_RPC_TIMEOUT,
+            self.pairing_timeout,
             client.pairing_consent(PairingConsent {
                 accepted: true,
                 grant: Some(grant),
@@ -767,7 +805,7 @@ impl DeviceRelationshipService {
                     .await?;
                 if let Ok(Ok(PairingAckResponse::Acknowledged | PairingAckResponse::AlreadySaved)) =
                     tokio::time::timeout(
-                        PAIRING_RPC_TIMEOUT,
+                        self.pairing_timeout,
                         client.pairing_ack(PairingAck {
                             possession_proof: proof,
                             challenge: ack_challenge.encode(),
@@ -1483,7 +1521,7 @@ impl DeviceRelationshipService {
         };
         let client = RelationshipClient::connect(self.endpoint.clone(), addr);
         let _ = tokio::time::timeout(
-            PAIRING_RPC_TIMEOUT,
+            self.pairing_timeout,
             client.revoke_notice(RevokeNotice {
                 generation,
                 issued_grant_id,

crates/vnidrop/src/error.rs

@@ -55,7 +55,7 @@ impl VnidropError {
 
     pub(crate) fn ticket(error: impl Into<anyhow::Error>) -> Self {
         Self::Ticket {
-            reason: error.into().to_string(),
+            reason: crate::control_plane::redact_text(&error.into().to_string()),
         }
     }
 
@@ -168,7 +168,7 @@ impl VnidropError {
     }
 
     fn classify(error: anyhow::Error, fallback: impl FnOnce(String) -> Self) -> Self {
-        let reason = error.to_string();
+        let reason = crate::control_plane::redact_text(&error.to_string());
         if let Some(existing) = error.chain().find_map(|cause| cause.downcast_ref::<Self>()) {
             return existing.with_reason(reason);
         }
@@ -193,7 +193,7 @@ impl VnidropError {
     }
 
     fn from_error(error: anyhow::Error, fallback: impl FnOnce(String) -> Self) -> Self {
-        let reason = error.to_string();
+        let reason = crate::control_plane::redact_text(&error.to_string());
         if let Some(existing) = error.chain().find_map(|cause| cause.downcast_ref::<Self>()) {
             existing.with_reason(reason)
         } else {

crates/vnidrop/src/event_hub.rs

@@ -8,6 +8,7 @@ use tokio::{
 
 use crate::{
     api::{CoreEvent, CoreEventSink},
+    control_plane::redact_json,
     repository::Repository,
     transfer_state::TransferDirection,
     util::now_ms,
@@ -51,6 +52,10 @@ enum EventPhase {
     Pairing,
     /// Prototype contact lifecycle notifications.
     Contacts,
+    /// Prototype contact offer prompts.
+    Offer,
+    /// Saved-device targeted-transfer pre-approval prompts.
+    TargetedTransfer,
 }
 
 impl EventPhase {
@@ -74,6 +79,8 @@ impl EventPhase {
             "delivery" => Some(Self::Delivery),
             "pairing" => Some(Self::Pairing),
             "contacts" => Some(Self::Contacts),
+            "offer" => Some(Self::Offer),
+            "targeted_transfer" => Some(Self::TargetedTransfer),
             _ => None,
         }
     }
@@ -98,6 +105,8 @@ impl EventPhase {
             Self::Delivery => "delivery",
             Self::Pairing => "pairing",
             Self::Contacts => "contacts",
+            Self::Offer => "offer",
+            Self::TargetedTransfer => "targeted_transfer",
         }
     }
 }
@@ -245,6 +254,8 @@ impl EventHub {
         // Compose observes this event synchronously, while SQLite persistence is
         // serialized through the queue.  That keeps the UI responsive without
         // losing the ability to flush persisted history during shutdown/tests.
+        // Production diagnostics redact endpoint ids, tickets, grants, and paths;
+        // typed UniFFI list APIs still expose the values the UI needs.
         let event = CoreEvent {
             id,
             timestamp,
@@ -253,7 +264,7 @@ impl EventHub {
             direction: direction.map(|direction| direction.as_str().to_string()),
             phase: phase.as_str().to_string(),
             kind: kind.0,
-            data_json: data.to_string(),
+            data_json: redact_json(data).to_string(),
         };
         if let Err(error) = self.tx.try_send(EventCommand::Persist(event.clone())) {
             tracing::warn!(event_id = %event.id, %error, "event persistence queue dropped event");

crates/vnidrop/src/lib.rs

@@ -2,6 +2,7 @@ mod access_policy;
 mod api;
 mod approval;
 mod contacts;
+mod control_plane;
 mod device_relationship;
 mod error;
 mod event_hub;

crates/vnidrop/src/offer_inbox.rs

@@ -20,10 +20,6 @@ use crate::{event_hub::EventHub, offer::OfferResponse, util::now_ms};
 /// How long the sender waits for the receiving user to decide.
 const OFFER_WAIT_TIMEOUT: Duration = Duration::from_secs(120);
 
-/// Quiet period after a decline, so a paired device cannot re-prompt on a loop.
-/// A contact is not a stranger, but it is not unlimited either.
-const DECLINE_COOLDOWN_MS: i64 = 60 * 1_000;
-
 #[derive(Debug, Clone)]
 pub(crate) struct PendingOffer {
     pub(crate) offer_id: String,
@@ -50,16 +46,22 @@ pub(crate) struct OfferInbox {
     /// Endpoint → time before which new offers are refused.
     cooldowns: Arc<Mutex<HashMap<String, i64>>>,
     max_pending: usize,
+    decline_cooldown_ms: i64,
 }
 
 impl OfferInbox {
-    pub(crate) fn new(event_hub: Arc<EventHub>, max_pending: usize) -> Self {
+    pub(crate) fn new(
+        event_hub: Arc<EventHub>,
+        max_pending: usize,
+        identity_cooldown_ms: u64,
+    ) -> Self {
         Self {
             event_hub,
             pending: Arc::new(Mutex::new(HashMap::new())),
             waiters: Arc::new(Mutex::new(HashMap::new())),
             cooldowns: Arc::new(Mutex::new(HashMap::new())),
             max_pending,
+            decline_cooldown_ms: identity_cooldown_ms as i64,
         }
     }
 
@@ -229,7 +231,7 @@ impl OfferInbox {
         if !accepted {
             self.cooldowns.lock().await.insert(
                 offer.from_endpoint_id.clone(),
-                now_ms() + DECLINE_COOLDOWN_MS,
+                now_ms() + self.decline_cooldown_ms,
             );
         }
         if let Some(waiter) = waiter {

crates/vnidrop/src/runtime/facade.rs

@@ -90,6 +90,22 @@ impl VnidropCore {
         event_sink: Arc<dyn CoreEventSink>,
         store: Arc<dyn crate::secure_secret::SecureSecretStore>,
         network_config: CoreNetworkConfig,
+    ) -> Result<Arc<Self>, VnidropError> {
+        Self::initialize_with_test_secret_store_limits_and_network(
+            app_data_dir,
+            event_sink,
+            store,
+            CoreLimits::default(),
+            network_config,
+        )
+    }
+
+    pub(crate) fn initialize_with_test_secret_store_limits_and_network(
+        app_data_dir: String,
+        event_sink: Arc<dyn CoreEventSink>,
+        store: Arc<dyn crate::secure_secret::SecureSecretStore>,
+        limits: CoreLimits,
+        network_config: CoreNetworkConfig,
     ) -> Result<Arc<Self>, VnidropError> {
         let app_data_path = PathBuf::from(&app_data_dir);
         std::fs::create_dir_all(&app_data_path).map_err(VnidropError::filesystem)?;
@@ -99,7 +115,7 @@ impl VnidropCore {
         Self::initialize_with_identity_mode(
             app_data_dir,
             event_sink,
-            CoreLimits::default(),
+            limits,
             network_config,
             IdentityMode::Protected {
                 store,

crates/vnidrop/src/runtime/mod.rs

@@ -394,9 +394,21 @@ impl CoreInner {
         {
             tracing::warn!(%error, "failed to sweep dead grants");
         }
-        let offers = OfferInbox::new(event_hub.clone(), limits.max_pending_offers as usize);
-        let targeted_offers =
-            TargetedOfferInbox::new(event_hub.clone(), limits.max_pending_offers as usize);
+        let offers = OfferInbox::new(
+            event_hub.clone(),
+            limits.max_pending_offers as usize,
+            limits.identity_cooldown_ms,
+        );
+        let identity_cooldown = crate::control_plane::IdentityCooldown::new(
+            limits.identity_cooldown_ms,
+            limits.malformed_strike_limit,
+        );
+        let targeted_offers = TargetedOfferInbox::new(
+            event_hub.clone(),
+            limits.max_pending_offers as usize,
+            identity_cooldown,
+            limits.offer_timeout_ms,
+        );
         let device_relationships = Arc::new(DeviceRelationshipService::new(
             repository.sqlite_pool(),
             secret_custody.clone(),
@@ -406,6 +418,8 @@ impl CoreInner {
             endpoint.clone(),
             relay_mode,
             relay_urls.clone(),
+            limits.max_saved_devices,
+            limits.pairing_timeout_ms,
         ));
         let router = Router::builder(endpoint.clone())
             .accept(iroh_blobs::ALPN, blobs)

crates/vnidrop/src/runtime/targeted.rs

@@ -27,9 +27,15 @@ use crate::{
     util::{non_empty, now_ms},
 };
 
-const OFFER_CONNECT_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(30);
-
 impl CoreInner {
+    fn connection_timeout(&self) -> std::time::Duration {
+        std::time::Duration::from_millis(self.limits.connection_timeout_ms)
+    }
+
+    fn offer_wait_timeout(&self) -> std::time::Duration {
+        std::time::Duration::from_millis(self.limits.offer_timeout_ms)
+    }
+
     pub(super) fn targeted_store(&self) -> TargetedTransferStore {
         TargetedTransferStore::new(self.repository.sqlite_pool())
     }
@@ -131,7 +137,7 @@ impl CoreInner {
             {
                 let client = TargetedTransferProtocol::client(self.endpoint.clone(), addr);
                 let _ = tokio::time::timeout(
-                    OFFER_CONNECT_TIMEOUT,
+                    self.connection_timeout(),
                     client.cancel_offer(CancelTargetedOffer {
                         transfer_id: id.clone(),
                     }),
@@ -287,7 +293,8 @@ impl CoreInner {
             .await?;
         let client = TargetedTransferProtocol::client(self.endpoint.clone(), addr);
         let challenge =
-            match tokio::time::timeout(OFFER_CONNECT_TIMEOUT, client.request_challenge()).await {
+            match tokio::time::timeout(self.connection_timeout(), client.request_challenge()).await
+            {
                 Ok(Ok(challenge)) => challenge,
                 Ok(Err(error)) => {
                     let _ = store
@@ -331,7 +338,7 @@ impl CoreInner {
             .await?;
 
         let response = match tokio::time::timeout(
-            OFFER_CONNECT_TIMEOUT + std::time::Duration::from_secs(120),
+            self.connection_timeout() + self.offer_wait_timeout(),
             client.submit_offer(SubmitTargetedOffer {
                 proof,
                 generation,

crates/vnidrop/src/targeted_transfer/inbox.rs

@@ -10,9 +10,7 @@ use serde_json::json;
 use tokio::sync::{watch, Mutex};
 use uuid::Uuid;
 
-use crate::{api::PendingTargetedOffer, event_hub::EventHub};
-
-const OFFER_WAIT_TIMEOUT: Duration = Duration::from_secs(120);
+use crate::{api::PendingTargetedOffer, control_plane::IdentityCooldown, event_hub::EventHub};
 
 #[derive(Debug, Clone)]
 pub(crate) struct PendingTargetedOfferRecord {
@@ -40,27 +38,45 @@ pub(crate) struct TargetedOfferInbox {
     decisions: Arc<Mutex<HashMap<String, PendingWaiter>>>,
     auths: Arc<Mutex<HashMap<String, AuthWaiter>>>,
     settled: Arc<Mutex<HashMap<String, SettledOfferResult>>>,
+    cooldown: IdentityCooldown,
     max_pending: usize,
+    offer_timeout: Duration,
 }
 
 impl TargetedOfferInbox {
-    pub(crate) fn new(event_hub: Arc<EventHub>, max_pending: usize) -> Self {
+    pub(crate) fn new(
+        event_hub: Arc<EventHub>,
+        max_pending: usize,
+        cooldown: IdentityCooldown,
+        offer_timeout_ms: u64,
+    ) -> Self {
         Self {
             event_hub,
             pending: Arc::new(Mutex::new(HashMap::new())),
             decisions: Arc::new(Mutex::new(HashMap::new())),
             auths: Arc::new(Mutex::new(HashMap::new())),
             settled: Arc::new(Mutex::new(HashMap::new())),
+            cooldown,
             max_pending,
+            offer_timeout: Duration::from_millis(offer_timeout_ms),
         }
     }
 
+    pub(crate) fn cooldown(&self) -> &IdentityCooldown {
+        &self.cooldown
+    }
+
     /// Surface a validated offer and block until the local user decides.
     ///
     /// Replaying the same transfer identity returns the settled result or joins
     /// the existing pending wait — never a second prompt.
     pub(crate) async fn submit(&self, offer: PendingTargetedOffer) -> TargetedOfferDecision {
         let transfer_id = offer.transfer_id.clone();
+        if self.cooldown.is_cooling(&offer.sender_endpoint_id) {
+            return TargetedOfferDecision::Refused {
+                reason: "identity-cooldown".to_string(),
+            };
+        }
         if let Some(settled) = self.settled.lock().await.get(&transfer_id).cloned() {
             return settled_to_decision(settled);
         }
@@ -76,11 +92,7 @@ impl TargetedOfferInbox {
                     reason: "immutable-transfer-mismatch".to_string(),
                 };
             }
-            if pending.len() >= self.max_pending {
-                return TargetedOfferDecision::Refused {
-                    reason: "too-many-pending-offers".to_string(),
-                };
-            }
+            // Prefer the more specific per-sender refusal before the global bound.
             if pending
                 .values()
                 .any(|entry| entry.offer.sender_endpoint_id == offer.sender_endpoint_id)
@@ -89,6 +101,11 @@ impl TargetedOfferInbox {
                     reason: "offer-already-pending".to_string(),
                 };
             }
+            if pending.len() >= self.max_pending {
+                return TargetedOfferDecision::Refused {
+                    reason: "too-many-pending-offers".to_string(),
+                };
+            }
         }
 
         let (decision_tx, _decision_rx) = watch::channel(None);
@@ -99,6 +116,19 @@ impl TargetedOfferInbox {
                 drop(pending);
                 return self.wait_existing_decision(&transfer_id).await;
             }
+            if pending
+                .values()
+                .any(|entry| entry.offer.sender_endpoint_id == offer.sender_endpoint_id)
+            {
+                return TargetedOfferDecision::Refused {
+                    reason: "offer-already-pending".to_string(),
+                };
+            }
+            if pending.len() >= self.max_pending {
+                return TargetedOfferDecision::Refused {
+                    reason: "too-many-pending-offers".to_string(),
+                };
+            }
             pending.insert(
                 transfer_id.clone(),
                 PendingTargetedOfferRecord {
@@ -112,6 +142,7 @@ impl TargetedOfferInbox {
                 decision: decision_tx,
             },
         );
+        self.cooldown.clear_strikes(&offer.sender_endpoint_id);
 
         self.event_hub.emit_endpoint(
             "targeted_transfer",
@@ -153,7 +184,7 @@ impl TargetedOfferInbox {
             }
         };
 
-        match tokio::time::timeout(OFFER_WAIT_TIMEOUT, wait).await {
+        match tokio::time::timeout(self.offer_timeout, wait).await {
             Ok(true) => TargetedOfferDecision::Accepted,
             Ok(false) => {
                 self.discard(transfer_id).await;
@@ -206,10 +237,15 @@ impl TargetedOfferInbox {
             return Ok(Some(auth));
         }
 
-        let exists = self.pending.lock().await.contains_key(transfer_id);
-        if !exists {
+        let sender_endpoint_id = {
+            let pending = self.pending.lock().await;
+            pending
+                .get(transfer_id)
+                .map(|entry| entry.offer.sender_endpoint_id.clone())
+        };
+        let Some(sender_endpoint_id) = sender_endpoint_id else {
             return Err(RespondError::Unknown);
-        }
+        };
         let waiter = {
             let decisions = self.decisions.lock().await;
             decisions
@@ -222,6 +258,7 @@ impl TargetedOfferInbox {
         if !accepted {
             let _ = decision_tx.send(Some(false));
             self.discard(transfer_id).await;
+            self.cooldown.record_decline(&sender_endpoint_id);
             self.settled.lock().await.insert(
                 transfer_id.to_string(),
                 SettledOfferResult::Declined {
@@ -258,7 +295,7 @@ impl TargetedOfferInbox {
             }
         };
 
-        match tokio::time::timeout(OFFER_WAIT_TIMEOUT, wait_auth).await {
+        match tokio::time::timeout(self.offer_timeout, wait_auth).await {
             Ok(Ok(auth)) => {
                 self.pending.lock().await.remove(transfer_id);
                 self.auths.lock().await.remove(transfer_id);

crates/vnidrop/src/targeted_transfer/protocol.rs

@@ -89,17 +89,25 @@ impl TargetedTransferProtocol {
         offer: SubmitTargetedOffer,
     ) -> TargetedOfferResponse {
         let expected = experimental_saved_device_capabilities().targeted_transfer_protocol_version;
+        if self.inbox.cooldown().is_cooling(remote_endpoint_id) {
+            return TargetedOfferResponse::Refused {
+                reason: "identity-cooldown".to_string(),
+            };
+        }
         if offer.protocol_version != expected {
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             return TargetedOfferResponse::Refused {
                 reason: "protocol-incompatible".to_string(),
             };
         }
         if offer.receiver_endpoint_id != self.local_endpoint_id {
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             return TargetedOfferResponse::Refused {
                 reason: "receiver-mismatch".to_string(),
             };
         }
         if offer.sender_endpoint_id != remote_endpoint_id {
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             return TargetedOfferResponse::Refused {
                 reason: "sender-mismatch".to_string(),
             };
@@ -112,6 +120,7 @@ impl TargetedTransferProtocol {
             || offer.manifest_id.is_empty()
             || offer.content_hash.is_empty()
         {
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             return TargetedOfferResponse::Refused {
                 reason: "manifest-limits".to_string(),
             };
@@ -120,6 +129,7 @@ impl TargetedTransferProtocol {
             .limits
             .validate_metadata_text("transfer name", Some(offer.transfer_name.as_str()))
         {
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             return TargetedOfferResponse::Refused {
                 reason: error.to_string(),
             };
@@ -190,7 +200,8 @@ impl TargetedTransferProtocol {
             )
             .await
         {
-            tracing::debug!(%error, "targeted offer relationship proof rejected");
+            tracing::debug!(error = %error, "targeted offer relationship proof rejected");
+            self.inbox.cooldown().record_malformed(remote_endpoint_id);
             if matches!(error, VnidropError::ProtocolIncompatible { .. }) {
                 return TargetedOfferResponse::Refused {
                     reason: "protocol-incompatible".to_string(),

crates/vnidrop/src/tests.rs

@@ -4,6 +4,8 @@ mod access_policy_tests;
 mod contact_polling_tests;
 #[path = "tests/contacts.rs"]
 mod contacts_tests;
+#[path = "tests/control_plane.rs"]
+mod control_plane_tests;
 #[path = "tests/device_relationship.rs"]
 mod device_relationship_tests;
 #[path = "tests/error.rs"]

crates/vnidrop/src/tests/control_plane.rs

@@ -0,0 +1,527 @@
+//! Control-plane hardening: offer bounds, cooldowns, saved-device cap, redaction.
+
+use std::sync::{Arc, Mutex};
+
+use crate::{
+    api::{CoreEvent, CoreEventSink, CoreLimits, PendingTargetedOffer},
+    control_plane::IdentityCooldown,
+    event_hub::EventHub,
+    repository::Repository,
+    secure_secret::FaultInjectingSecretStore,
+    targeted_transfer::inbox::{TargetedOfferDecision, TargetedOfferInbox},
+    CoreNetworkConfig, DeviceRelationshipState, ShareMetadataInput, ShareSource, SourceKind,
+    TransferAccessMode, VnidropCore, VnidropError,
+};
+
+struct RecordingSink {
+    events: Mutex<Vec<CoreEvent>>,
+}
+
+impl CoreEventSink for RecordingSink {
+    fn on_event(&self, event: CoreEvent) {
+        self.events.lock().unwrap().push(event);
+    }
+}
+
+impl RecordingSink {
+    fn events(&self) -> Vec<CoreEvent> {
+        self.events.lock().unwrap().clone()
+    }
+
+    fn kinds(&self) -> Vec<String> {
+        self.events().into_iter().map(|event| event.kind).collect()
+    }
+}
+
+fn sample_offer(transfer_id: &str, sender: &str) -> PendingTargetedOffer {
+    PendingTargetedOffer {
+        transfer_id: transfer_id.to_string(),
+        sender_endpoint_id: sender.to_string(),
+        receiver_endpoint_id: "receiver".to_string(),
+        manifest_id: "manifest".to_string(),
+        content_hash: "hash".to_string(),
+        transfer_name: "secret-name.pdf".to_string(),
+        file_count: 1,
+        total_size: 12,
+        protocol_version: 1,
+        received_at: 1,
+    }
+}
+
+async fn inbox_with_limits(
+    max_pending: usize,
+    cooldown_ms: u64,
+    strikes: u64,
+) -> (TargetedOfferInbox, Arc<RecordingSink>) {
+    let temp = tempfile::tempdir().unwrap();
+    let repository = Repository::open(temp.path()).await.unwrap();
+    let sink = Arc::new(RecordingSink {
+        events: Mutex::new(Vec::new()),
+    });
+    let hub = Arc::new(EventHub::start(repository, sink.clone(), 64, 100));
+    let cooldown = IdentityCooldown::new(cooldown_ms, strikes);
+    let inbox = TargetedOfferInbox::new(hub, max_pending, cooldown, 5_000);
+    // Keep temp dir alive for the hub's repository by leaking — tests are short-lived.
+    std::mem::forget(temp);
+    (inbox, sink)
+}
+
+#[tokio::test]
+async fn one_unresolved_offer_per_sender_and_global_queue_bound() {
+    let (inbox, sink) = inbox_with_limits(1, 60_000, 5).await;
+
+    let first = sample_offer("t1", "sender-a");
+    let submit_first = {
+        let inbox = inbox.clone();
+        tokio::spawn(async move { inbox.submit(first).await })
+    };
+    // Wait until the prompt is live.
+    let started = std::time::Instant::now();
+    loop {
+        if !inbox.list().await.is_empty() {
+            break;
+        }
+        assert!(started.elapsed() < std::time::Duration::from_secs(2));
+        tokio::time::sleep(std::time::Duration::from_millis(5)).await;
+    }
+    assert!(sink.kinds().contains(&"offer-received".to_string()));
+
+    let same_sender = inbox.submit(sample_offer("t2", "sender-a")).await;
+    assert_eq!(
+        same_sender,
+        TargetedOfferDecision::Refused {
+            reason: "offer-already-pending".to_string()
+        }
+    );
+
+    let other_sender = inbox.submit(sample_offer("t3", "sender-b")).await;
+    assert_eq!(
+        other_sender,
+        TargetedOfferDecision::Refused {
+            reason: "too-many-pending-offers".to_string()
+        }
+    );
+    assert_eq!(inbox.list().await.len(), 1);
+    // Excess rejects never emit a second prompt.
+    assert_eq!(
+        sink.kinds()
+            .into_iter()
+            .filter(|kind| kind == "offer-received")
+            .count(),
+        1
+    );
+
+    inbox.respond("t1", false).await.unwrap();
+    let _ = submit_first.await.unwrap();
+}
+
+#[tokio::test]
+async fn decline_cools_sender_without_affecting_unrelated_devices() {
+    let (inbox, _sink) = inbox_with_limits(8, 60_000, 5).await;
+    let offer = sample_offer("decline-1", "noisy");
+    let wait = {
+        let inbox = inbox.clone();
+        tokio::spawn(async move { inbox.submit(offer).await })
+    };
+    let started = std::time::Instant::now();
+    loop {
+        if inbox.get_pending("decline-1").await.is_some() {
+            break;
+        }
+        assert!(started.elapsed() < std::time::Duration::from_secs(2));
+        tokio::time::sleep(std::time::Duration::from_millis(5)).await;
+    }
+    inbox.respond("decline-1", false).await.unwrap();
+    let _ = wait.await.unwrap();
+
+    let cooled = inbox.submit(sample_offer("decline-2", "noisy")).await;
+    assert_eq!(
+        cooled,
+        TargetedOfferDecision::Refused {
+            reason: "identity-cooldown".to_string()
+        }
+    );
+    assert!(inbox.list().await.is_empty());
+
+    let unrelated = {
+        let inbox = inbox.clone();
+        tokio::spawn(async move { inbox.submit(sample_offer("ok", "friend")).await })
+    };
+    let started = std::time::Instant::now();
+    loop {
+        if inbox.get_pending("ok").await.is_some() {
+            break;
+        }
+        assert!(started.elapsed() < std::time::Duration::from_secs(2));
+        tokio::time::sleep(std::time::Duration::from_millis(5)).await;
+    }
+    inbox.respond("ok", false).await.unwrap();
+    let _ = unrelated.await.unwrap();
+}
+
+#[tokio::test]
+async fn malformed_strikes_trip_cooldown() {
+    let cooldown = IdentityCooldown::new(60_000, 2);
+    assert!(!cooldown.record_malformed("attacker"));
+    assert!(cooldown.record_malformed("attacker"));
+    assert!(cooldown.is_cooling("attacker"));
+    assert!(!cooldown.is_cooling("bystander"));
+}
+
+#[tokio::test]
+async fn offer_received_events_redact_endpoint_ids_and_names() {
+    let (inbox, sink) = inbox_with_limits(4, 60_000, 5).await;
+    let sender = "abc123endpointid000000000000000000000000000000000000000000000000";
+    let wait = {
+        let inbox = inbox.clone();
+        let offer = sample_offer("redact-1", sender);
+        tokio::spawn(async move { inbox.submit(offer).await })
+    };
+    let started = std::time::Instant::now();
+    loop {
+        if sink
+            .kinds()
+            .into_iter()
+            .any(|kind| kind == "offer-received")
+        {
+            break;
+        }
+        assert!(started.elapsed() < std::time::Duration::from_secs(2));
+        tokio::time::sleep(std::time::Duration::from_millis(5)).await;
+    }
+    let event = sink
+        .events()
+        .into_iter()
+        .find(|event| event.kind == "offer-received")
+        .expect("offer event");
+    assert!(!event.data_json.contains(sender));
+    assert!(!event.data_json.contains("secret-name"));
+    assert!(event.data_json.contains("redacted"));
+    inbox.respond("redact-1", false).await.unwrap();
+    let _ = wait.await.unwrap();
+}
+
+struct ProtectedNode {
+    _data_dir: tempfile::TempDir,
+    _secret_store: Arc<FaultInjectingSecretStore>,
+    _limits: CoreLimits,
+    _network_config: CoreNetworkConfig,
+    sink: Arc<RecordingSink>,
+    core: Option<Arc<VnidropCore>>,
+}
+
+impl ProtectedNode {
+    fn with_limits(limits: CoreLimits) -> Self {
+        let data_dir = tempfile::tempdir().unwrap();
+        let sink = Arc::new(RecordingSink {
+            events: Mutex::new(Vec::new()),
+        });
+        let store = Arc::new(FaultInjectingSecretStore::default());
+        let network_config = CoreNetworkConfig::default();
+        let core = VnidropCore::initialize_with_test_secret_store_limits_and_network(
+            data_dir.path().to_string_lossy().into_owned(),
+            sink.clone(),
+            store.clone(),
+            limits.clone(),
+            network_config.clone(),
+        )
+        .expect("protected test core");
+        Self {
+            _data_dir: data_dir,
+            _secret_store: store,
+            _limits: limits,
+            _network_config: network_config,
+            sink,
+            core: Some(core),
+        }
+    }
+
+    fn core(&self) -> Arc<VnidropCore> {
+        self.core.as_ref().expect("core alive").clone()
+    }
+}
+
+impl Drop for ProtectedNode {
+    fn drop(&mut self) {
+        if let Some(core) = self.core.take() {
+            core.shutdown();
+        }
+    }
+}
+
+fn share_path(
+    core: &VnidropCore,
+    source: &std::path::Path,
+    transfer_id: u64,
+) -> crate::ShareResult {
+    core.share_files(
+        vec![ShareSource {
+            kind: SourceKind::Path,
+            value: source.to_string_lossy().into_owned(),
+            display_name: Some("hello.txt".to_string()),
+            is_directory: false,
+        }],
+        ShareMetadataInput {
+            transfer_id,
+            transfer_name: Some("hello.txt".to_string()),
+            sender_name: Some("sender".to_string()),
+            access_mode: TransferAccessMode::ApprovalRequired,
+        },
+    )
+    .unwrap()
+}
+
+fn wait_for_receiver_request(sender: &VnidropCore, transfer_id: u64) -> crate::ReceiverRequest {
+    let started = std::time::Instant::now();
+    loop {
+        if let Some(request) = sender
+            .list_receiver_requests(transfer_id)
+            .unwrap()
+            .into_iter()
+            .find(|request| request.status == "requested")
+        {
+            return request;
+        }
+        assert!(
+            started.elapsed() < std::time::Duration::from_secs(15),
+            "timed out waiting for receiver request"
+        );
+        std::thread::sleep(std::time::Duration::from_millis(25));
+    }
+}
+
+fn complete_transfer(sender: &ProtectedNode, receiver: &ProtectedNode, transfer_id: u64) {
+    let source_dir = tempfile::tempdir().unwrap();
+    let output_dir = tempfile::tempdir().unwrap();
+    let source_path = source_dir.path().join("hello.txt");
+    std::fs::write(&source_path, b"mutual consent").unwrap();
+    let share = share_path(&sender.core(), &source_path, transfer_id);
+    let output_dir = output_dir.path().to_string_lossy().to_string();
+    let receiver_core = receiver.core().clone();
+    let ticket = share.ticket.clone();
+    let handle = std::thread::spawn(move || {
+        receiver_core.receive(ticket, output_dir, Some("receiver".to_string()))
+    });
+    let request = wait_for_receiver_request(&sender.core(), share.transfer_id);
+    sender
+        .core()
+        .respond_receiver_request(request.id, true, None)
+        .unwrap();
+    handle.join().unwrap().unwrap();
+
+    let started = std::time::Instant::now();
+    let peer = receiver.core().status().endpoint_id.clone();
+    loop {
+        if sender
+            .core()
+            .list_pairing_eligibilities()
+            .unwrap()
+            .iter()
+            .any(|entry| entry.peer_endpoint_id == peer)
+        {
+            break;
+        }
+        assert!(
+            started.elapsed() < std::time::Duration::from_secs(15),
+            "eligibility never appeared"
+        );
+        std::thread::sleep(std::time::Duration::from_millis(25));
+    }
+}
+
+fn establish_saved(alice: &ProtectedNode, bob: &ProtectedNode, transfer_id: u64) {
+    complete_transfer(alice, bob, transfer_id);
+    let bob_id = bob.core().status().endpoint_id.clone();
+    assert!(alice
+        .core()
+        .request_saved_device_pairing(bob_id.clone())
+        .unwrap());
+    let started = std::time::Instant::now();
+    loop {
+        let pending = bob
+            .core()
+            .list_device_relationships()
+            .unwrap()
+            .into_iter()
+            .find(|entry| {
+                entry.remote_endpoint_id == alice.core().status().endpoint_id
+                    && entry.state == DeviceRelationshipState::PendingIncoming
+            });
+        if pending.is_some() {
+            break;
+        }
+        assert!(
+            started.elapsed() < std::time::Duration::from_secs(15),
+            "pairing prompt never arrived"
+        );
+        std::thread::sleep(std::time::Duration::from_millis(25));
+    }
+    assert!(bob
+        .core()
+        .respond_to_device_pairing(alice.core().status().endpoint_id.clone(), true)
+        .unwrap());
+    let started = std::time::Instant::now();
+    loop {
+        if alice.core().list_saved_devices().unwrap().len() == 1
+            && bob.core().list_saved_devices().unwrap().len() == 1
+        {
+            break;
+        }
+        assert!(
+            started.elapsed() < std::time::Duration::from_secs(15),
+            "saved relationship never activated"
+        );
+        std::thread::sleep(std::time::Duration::from_millis(25));
+    }
+}
+
+#[test]
+fn default_limits_include_saved_device_cap_and_control_plane_timeouts() {
+    let limits = CoreLimits::default();
+    limits.validate().unwrap();
+    assert_eq!(limits.max_saved_devices, 256);
+    assert!(limits.identity_cooldown_ms > 0);
+    assert!(limits.malformed_strike_limit > 0);
+    assert!(limits.pairing_timeout_ms > 0);
+    assert!(limits.offer_timeout_ms > 0);
+    assert!(limits.connection_timeout_ms > 0);
+    assert!(
+        limits.max_pending_offers <= 64,
+        "pending offers stay tightly bounded"
+    );
+}
+
+#[test]
+fn saved_device_cap_blocks_only_new_relationships() {
+    let tight = CoreLimits {
+        max_saved_devices: 1,
+        ..CoreLimits::default()
+    };
+    let alice = ProtectedNode::with_limits(tight.clone());
+    let bob = ProtectedNode::with_limits(tight.clone());
+    let carol = ProtectedNode::with_limits(tight);
+
+    establish_saved(&alice, &bob, 13_001);
+    assert_eq!(alice.core().list_saved_devices().unwrap().len(), 1);
+
+    // Existing relationship remains usable for targeted transfer.
+    let source_dir = tempfile::tempdir().unwrap();
+    let source_path = source_dir.path().join("payload.txt");
+    std::fs::write(&source_path, b"still works").unwrap();
+    let bob_id = bob.core().status().endpoint_id.clone();
+    let bob_core = bob.core().clone();
+    let accept = std::thread::spawn(move || {
+        let started = std::time::Instant::now();
+        let offer = loop {
+            if let Some(offer) = bob_core.list_pending_targeted_offers().into_iter().next() {
+                break offer;
+            }
+            assert!(
+                started.elapsed() < std::time::Duration::from_secs(20),
+                "offer never arrived for existing saved peer"
+            );
+            std::thread::sleep(std::time::Duration::from_millis(25));
+        };
+        bob_core
+            .respond_to_targeted_offer(offer.transfer_id, true)
+            .unwrap()
+    });
+    alice
+        .core()
+        .create_targeted_transfer(
+            bob_id,
+            vec![ShareSource {
+                kind: SourceKind::Path,
+                value: source_path.to_string_lossy().into_owned(),
+                display_name: Some("payload.txt".to_string()),
+                is_directory: false,
+            }],
+            Some("payload.txt".to_string()),
+        )
+        .unwrap();
+    accept.join().unwrap().unwrap();
+
+    // New relationship is refused while the cap is full.
+    complete_transfer(&alice, &carol, 13_002);
+    let carol_id = carol.core().status().endpoint_id.clone();
+    assert!(
+        !alice.core().request_saved_device_pairing(carol_id).unwrap(),
+        "cap must block only new relationships"
+    );
+    assert!(alice.core().list_saved_devices().unwrap().len() <= 1);
+    assert!(carol.core().list_saved_devices().unwrap().is_empty());
+}
+
+#[test]
+fn silent_reject_keeps_invalid_offers_off_the_prompt_surface() {
+    let alice = ProtectedNode::with_limits(CoreLimits::default());
+    let bob = ProtectedNode::with_limits(CoreLimits::default());
+    // No Saved relationship — create must fail before any receiver prompt.
+    let bob_id = bob.core().status().endpoint_id.clone();
+    let source_dir = tempfile::tempdir().unwrap();
+    let source_path = source_dir.path().join("payload.txt");
+    std::fs::write(&source_path, b"nope").unwrap();
+    let err = alice
+        .core()
+        .create_targeted_transfer(
+            bob_id,
+            vec![ShareSource {
+                kind: SourceKind::Path,
+                value: source_path.to_string_lossy().into_owned(),
+                display_name: Some("payload.txt".to_string()),
+                is_directory: false,
+            }],
+            Some("payload.txt".to_string()),
+        )
+        .unwrap_err();
+    assert!(matches!(err, VnidropError::Permission { .. }));
+    assert!(bob.core().list_pending_targeted_offers().is_empty());
+    assert!(
+        !bob.sink
+            .kinds()
+            .into_iter()
+            .any(|kind| kind == "offer-received"),
+        "silent reject must not emit offer prompts"
+    );
+}
+
+#[test]
+fn blocked_peer_cannot_create_pairing_prompt() {
+    let alice = ProtectedNode::with_limits(CoreLimits::default());
+    let bob = ProtectedNode::with_limits(CoreLimits::default());
+    complete_transfer(&alice, &bob, 13_010);
+    let alice_id = alice.core().status().endpoint_id.clone();
+    bob.core().block_device(alice_id.clone()).unwrap();
+    assert!(
+        !alice
+            .core()
+            .request_saved_device_pairing(bob.core().status().endpoint_id.clone())
+            .unwrap()
+            || bob
+                .core()
+                .list_device_relationships()
+                .unwrap()
+                .iter()
+                .all(|entry| entry.state != DeviceRelationshipState::PendingIncoming)
+    );
+    // Stronger: after block, bob must not surface an incoming pairing prompt.
+    std::thread::sleep(std::time::Duration::from_millis(200));
+    assert!(bob
+        .core()
+        .list_device_relationships()
+        .unwrap()
+        .into_iter()
+        .filter(|entry| entry.remote_endpoint_id == alice_id)
+        .all(|entry| entry.state != DeviceRelationshipState::PendingIncoming));
+}
+
+#[test]
+fn ticket_errors_redact_raw_ticket_blobs() {
+    let err = VnidropError::ticket(anyhow::anyhow!(
+        "bad ticket vnd1:abcDEF1234567890 and endpoint 0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+    ));
+    let rendered = err.to_string();
+    assert!(!rendered.contains("vnd1:abcDEF"));
+    assert!(!rendered.contains("0123456789abcdef0123456789abcdef"));
+    assert!(rendered.contains("[redacted]"));
+}

crates/vnidrop/src/tests/limits.rs

@@ -11,6 +11,8 @@ fn default_limits_bound_ticket_and_approval_pressure() {
     assert!(limits.max_ticket_bytes <= 256 * 1024);
     assert!(limits.max_pending_approvals <= 64);
     assert!(limits.max_total_bytes <= 256 * 1024 * 1024 * 1024);
+    assert_eq!(limits.max_saved_devices, 256);
+    assert!(limits.max_pending_offers <= 16);
 }
 
 #[test]
@@ -21,3 +23,12 @@ fn zero_limit_is_rejected() {
     };
     assert!(limits.validate().is_err());
 }
+
+#[test]
+fn zero_saved_device_limit_is_rejected() {
+    let limits = CoreLimits {
+        max_saved_devices: 0,
+        ..CoreLimits::default()
+    };
+    assert!(limits.validate().is_err());
+}

crates/vnidrop/tests/transfer.rs

@@ -98,9 +98,11 @@ fn transfers_file_between_two_cores() {
     let completed = wait_for_sender_transfer_event(&sender, share.transfer_id, "completed");
     assert!(completed.data_json.contains("\"connection_id\":"));
     assert!(completed.data_json.contains("\"request_id\":"));
-    assert!(completed
+    // Production events redact endpoint ids; typed APIs remain the source of truth.
+    assert!(!completed
         .data_json
         .contains(receiver.core.status().endpoint_id.as_str()));
+    assert!(completed.data_json.contains("redacted"));
 
     receiver.core.delete_receive_history().unwrap();
     assert_eq!(receiver.core.list_received_artifacts().unwrap(), artifacts);