feat(payment)!: enforce the close-group price floor on every node

docs/adr/ADR-0008-storage-economics-and-payment-protocol.md

@@ -359,7 +359,7 @@ and a node that was actually paid is nominated for a first audit.
 | Node re-verification of **non-paid** quotes in the bundle | not done (bad signature on an unpaid quote is accepted) |
 | Node rejection of off-curve quotes (`QUOTE_ARITHMETIC_RECHECK_ENABLED`) | **enforced**, on every quote in the bundle |
 | Quote/commitment mismatch reported to trust | off (telemetry only) |
-| Receiver-side price floor (ADR-0006) | shadow (`ANT_PRICE_FLOOR_ENFORCE`, 65% tolerance), priced against the **close group's median** committed count, not the receiver's own; the own-price basis was withdrawn after canary measurement |
+| Receiver-side price floor (ADR-0006) | **enforced** on every node at 30% of a reference price: the **close group's median** committed-count price, capped at the receiver's own; covers client PUT, fresh replication and paid-list admission; no per-node switch (ADR-0006 Amendment 2) |
 | Payee eligibility gate (ADR-0005) | **not merged**; observe-only on its branch (`ADR5_ENFORCE`) |
 | Client pays the 3× multiplier on the merkle path | **enforced** by the published client, immediately and unconditionally (no flag, no date) |
 | Storer requires it (`MERKLE_PARITY_ENFORCED_FROM_UNIX`) | **enforced** by upgraded nodes, for receipts stamped from 2026-08-04 15:00 UTC onward |
@@ -452,7 +452,9 @@ indistinguishable from a single receipt.
   mechanism to reprice.
 - **Median-of-K is only as honest as the quote set the client presents.** A
   modified client can shop the neighbourhood and settle the cheapest valid
-  quote; the receiver-side floor is the counterweight and is not yet enforcing.
+  quote. The receiver-side floor, enforced on every node (ADR-0006 Amendment
+  2), is the counterweight: it refuses near-empty quotes, but not the
+  cheapest member of the close group.
 
 ### Neutral / Operational
 

src/devnet.rs

@@ -7,7 +7,7 @@ use crate::ant_protocol::CHUNK_PROTOCOL_ID;
 use crate::config::{default_root_dir, NODES_SUBDIR, NODE_IDENTITY_FILENAME};
 use crate::logging::{debug, info, warn};
 use crate::payment::{
-    EvmVerifierConfig, PaymentVerifier, PaymentVerifierConfig, PriceFloorConfig, QuoteGenerator,
+    EvmVerifierConfig, PaymentVerifier, PaymentVerifierConfig, QuoteGenerator,
     QuotingMetricsTracker,
 };
 use crate::replication::config::ReplicationConfig;
@@ -960,7 +960,6 @@ impl Devnet {
             cache_capacity: DEVNET_PAYMENT_CACHE_CAPACITY,
             close_group_size: replication_config.close_group_size,
             local_rewards_address: rewards_address,
-            price_floor: PriceFloorConfig::default(),
         };
         let payment_verifier = PaymentVerifier::new(payment_config);
         let metrics_tracker = QuotingMetricsTracker::new(DEVNET_INITIAL_RECORDS);

src/node.rs

@@ -9,9 +9,7 @@ use crate::event::{create_event_channel, NodeEvent, NodeEventsChannel, NodeEvent
 use crate::logging::{debug, error, info, warn};
 use crate::payment::metrics::QuotingMetricsTracker;
 use crate::payment::wallet::parse_rewards_address;
-use crate::payment::{
-    EvmVerifierConfig, PaymentVerifier, PaymentVerifierConfig, PriceFloorConfig, QuoteGenerator,
-};
+use crate::payment::{EvmVerifierConfig, PaymentVerifier, PaymentVerifierConfig, QuoteGenerator};
 use crate::replication::config::ReplicationConfig;
 use crate::replication::fresh::FreshWriteEvent;
 use crate::replication::ReplicationEngine;
@@ -504,16 +502,7 @@ impl NodeBuilder {
             cache_capacity: config.payment.cache_capacity,
             close_group_size,
             local_rewards_address: rewards_address,
-            // Shadow mode by default; enforcement is a per-node canary opt-in
-            // via ANT_PRICE_FLOOR_ENFORCE (see PriceFloorConfig).
-            price_floor: PriceFloorConfig::from_env(),
         };
-        if payment_config.price_floor.enforce {
-            info!(
-                "Price floor ENFORCEMENT enabled (tolerance {}%)",
-                payment_config.price_floor.tolerance_percent
-            );
-        }
         let payment_verifier = PaymentVerifier::new(payment_config);
         let metrics_tracker = QuotingMetricsTracker::new(0);
         let mut quote_generator = QuoteGenerator::new(rewards_address, metrics_tracker);

src/payment/mod.rs

@@ -63,8 +63,7 @@ pub use ant_protocol::payment::verify::{
 };
 pub use single_node::SingleNodePayment;
 pub use verifier::{
-    EvmVerifierConfig, PaymentStatus, PaymentVerifier, PaymentVerifierConfig, PriceFloorConfig,
-    VerificationContext, MAX_PAYMENT_PROOF_SIZE_BYTES, MIN_PAYMENT_PROOF_SIZE_BYTES,
-    PRICE_FLOOR_ENFORCE_ENV, PRICE_FLOOR_TOLERANCE_ENV,
+    EvmVerifierConfig, PaymentStatus, PaymentVerifier, PaymentVerifierConfig, VerificationContext,
+    MAX_PAYMENT_PROOF_SIZE_BYTES, MIN_PAYMENT_PROOF_SIZE_BYTES, PRICE_FLOOR_TOLERANCE_PERCENT,
 };
 pub use wallet::{is_valid_address, parse_rewards_address, WalletConfig};