feat(ops): read-only interception preflight for OpenFUT endpoints

During the Rust production cutover four stale openfut-switch nft rules were
still redirecting production-facing traffic to staging (42127->42227,
8081->8281, 8094->18094, 8099->18106). They matched `ip daddr 10.10.0.120`, so
every server-side probe via 127.0.0.1 or the container IP passed while the
CLIENT was refused. That cost a full false-negative acceptance round: a retail
quick-sell landed on staging while production sat untouched, and the launcher
reported the server "not answering".

The failure mode is mechanical, so the check is:

  * openfut-switch.sh status
  * nft rules on OpenFUT ports, split into REDIRECT (interception) and DNAT
    (docker publishing, expected -- reporting those as problems would train the
    reader to ignore the tool)
  * the actual point: loopback vs the ADVERTISED address per port. A redirect
    keyed on the LAN IP is invisible to loopback, which is exactly why the
    cutover probes all passed.

Verdict is CLEAN / INTERCEPTION_PRESENT with exit 0/1/2. Both branches
observed: it reports CLEAN now, and reported INTERCEPTION_PRESENT on a
loopback/advertised disagreement before :4216 was excluded.

:4216 is excluded from the verdict because LSX runs on the game machine --
compose publishes the port but OPENFUT_SERVERS omits lsx, so "published but not
served" is its normal state. It is still printed, marked as expected.

READ-ONLY by design: it never deletes a rule. Clearing interception stays a
deliberate operator act via `openfut-switch.sh off --name <id>`.

Run before production acceptance, client repoints, migrations and retail
protocol tests.

openfut-adapter-fifa17/src/fut/consumables.rs

@@ -33,8 +33,40 @@
 
 use serde_json::{json, Value};
 
+use crate::fut::discard;
 use crate::fut::item::{shape_consumable_item, Fifa17ConsumableIdentity, ShapeStats};
 
+/// The stack's `discardValue` (atom 0xd7) — the number the consumables screen
+/// DISPLAYS, per card.
+///
+/// This used to be hard-coded `0`, on the theory that the client would compute
+/// the price itself from `fcc_discardcoins` the way it does for a card whose
+/// `discardValue` we omit. That theory was wrong, and the screen showed
+/// "Quick sell for 0 coins" on a real production club (operator-observed,
+/// 2026-08-22) while Core would have paid 3/13/32 for those same contracts.
+///
+/// Why the old reasoning failed, from evidence rather than re-derivation:
+///
+/// * `item+0x38` (the `discardValue` we send) non-zero makes the client SKIP its
+///   local computation and display our number — live-proven again on the
+///   production client, 16/16 resident cards `SERVER-SHOWN`.
+/// * We send no `discardValue` inside a consumable's `item`, so `+0x38` is 0 and
+///   the client's local computation DOES run, filling `+0x3c` with the right
+///   value — Milestone 1 measured exactly that (3/3/32/38, matching this table).
+/// * The screen nonetheless showed 0. So the screen is not reading the item's
+///   computed `+0x3c`; it reads the STACK's atom 0xd7, which we were sending as
+///   0.
+///
+/// So the value belongs here, and it is the SAME number
+/// [`discard::value_for_definition`] gives the quick-sell payout — one source, so
+/// the screen and the wallet cannot disagree. Per CARD, not per stack: FUT
+/// prices a card, and the stack is only a quantity badge over identical copies.
+///
+/// `None` (definition not priceable) stays `0` rather than inventing a number.
+fn stack_discard_value(id: &Fifa17ConsumableIdentity) -> i64 {
+    discard::value_for_definition(id.subtype, id.rareflag, Some(id.rating), id.rating).unwrap_or(0)
+}
+
 /// Build the consumables-screen body from the club's owned consumable copies.
 ///
 /// Copies are collapsed by `resourceId` into one stack each, in first-seen order
@@ -43,10 +75,10 @@ use crate::fut::item::{shape_consumable_item, Fifa17ConsumableIdentity, ShapeSta
 /// counted — see [`Fifa17ConsumableIdentity::is_renderable`]; drawing "-1" or a
 /// different item than the club owns is worse than omitting the stack.
 ///
-/// `discardValue` is `0`: the client computes a card's own quick-sell price from
+/// `discardValue` carries the card's real quick-sell price — see
-/// `fcc_discardcoins` on `(cardtype 6, level, rare)`, and `0` is the value the
+/// [`stack_discard_value`]. It used to be `0` on the theory that the client
-/// live-proven oracle sends on this route. Inventing a price from the player
+/// priced the card itself; the production screen showed "Quick sell for 0 coins"
-/// quick-sell table would be a fabricated number the client does not need.
+/// instead, so the stack atom is what the screen reads.
 ///
 /// The stack's `item` is the FIRST copy, so its `id` is a real owned wire id — a
 /// later item operation on the stack therefore addresses a card the club really
@@ -78,7 +110,7 @@ pub fn consumables_response(items: &[Fifa17ConsumableIdentity]) -> (Value, Shape
                 order.push(id.resource_id);
                 stacks.push(json!({
                     "count": 1,
-                    "discardValue": 0,
+                    "discardValue": stack_discard_value(id),
                     "item": shape_consumable_item(*id),
                     "resourceId": id.resource_id,
                     "untradeableCount": i64::from(id.untradeable),
@@ -109,6 +141,80 @@ mod tests {
         }
     }
 
+    /// A contract card of the given subtype/rating — the family the production
+    /// screen showed as "0 coins".
+    fn contract(
+        item_id: u32,
+        resource_id: u32,
+        subtype: i64,
+        rating: u8,
+    ) -> Fifa17ConsumableIdentity {
+        Fifa17ConsumableIdentity {
+            item_id,
+            resource_id,
+            asset_id: resource_id,
+            card_asset_id: 7,
+            subtype,
+            rareflag: 0,
+            rating,
+            amount: None,
+            contract: Some(1),
+            untradeable: true,
+        }
+    }
+
+    /// The stack atom the screen reads MUST carry the same number the quick-sell
+    /// pays. A production club displayed "Quick sell for 0 coins" for contracts
+    /// Core would have paid 3/13/32 for; nothing may reintroduce that gap.
+    #[test]
+    fn stack_discard_value_is_the_payout_and_never_a_silent_zero() {
+        // The three contracts owned by the real production club.
+        let items = vec![
+            contract(1, 5_001_004, 201, 60),
+            contract(2, 5_001_008, 202, 65),
+            contract(3, 5_001_009, 202, 80),
+        ];
+        let (body, _) = consumables_response(&items);
+        let stacks = body["itemData"].as_array().unwrap();
+        assert_eq!(stacks.len(), 3);
+        for (stack, id) in stacks.iter().zip(items.iter()) {
+            let shown = stack["discardValue"].as_i64().unwrap();
+            let paid =
+                discard::value_for_definition(id.subtype, id.rareflag, Some(id.rating), id.rating)
+                    .expect("a contract definition is priceable");
+            assert_eq!(
+                shown, paid,
+                "displayed must equal payout for {}",
+                id.resource_id
+            );
+            assert!(
+                shown > 0,
+                "{} priced at 0 is the bug we just fixed",
+                id.resource_id
+            );
+        }
+        // The exact recovered values, so a table regression is visible here too.
+        assert_eq!(stacks[0]["discardValue"], 3);
+        assert_eq!(stacks[1]["discardValue"], 13);
+        assert_eq!(stacks[2]["discardValue"], 32);
+    }
+
+    /// Collapsing copies must not multiply the price: FUT prices a CARD, and the
+    /// stack is a quantity badge over identical copies.
+    #[test]
+    fn stack_discard_value_is_per_card_not_per_stack() {
+        let items = vec![
+            contract(1, 5_001_009, 202, 80),
+            contract(2, 5_001_009, 202, 80),
+            contract(3, 5_001_009, 202, 80),
+        ];
+        let (body, _) = consumables_response(&items);
+        let stacks = body["itemData"].as_array().unwrap();
+        assert_eq!(stacks.len(), 1);
+        assert_eq!(stacks[0]["count"], 3);
+        assert_eq!(stacks[0]["discardValue"], 32, "per card, not 3 x 32");
+    }
+
     #[test]
     fn identical_copies_collapse_into_one_counted_stack() {
         // Two copies of 5003103 plus one of 5003112 → two stacks, counts 2 and 1.

scripts/openfut-interception-preflight.py

@@ -0,0 +1,172 @@
+#!/usr/bin/env python3
+"""Report host-level packet interception affecting OpenFUT endpoints.
+
+WHY THIS EXISTS
+---------------
+During the 2026-08-22 Rust production cutover, four stale `openfut-switch` nft
+rules were still redirecting production-facing traffic to staging:
+
+    42127 -> :42227    8081 -> :8281    8094 -> :18094    8099 -> :18106
+
+They matched `ip daddr 10.10.0.120`, so every server-side probe via 127.0.0.1 or
+the container IP passed while the CLIENT was refused or silently sent to
+staging. That cost an entire false-negative acceptance round: a retail
+quick-sell landed on staging while production sat untouched, and the launcher
+reported "OpenFUT server is not answering".
+
+The lesson is mechanical, so the check is too: a connectivity gate that only
+probes loopback proves nothing about what the client reaches.
+
+READ-ONLY. This tool never deletes a rule. Removing interception is a
+deliberate operator act (`openfut-switch.sh off --name <id>`).
+
+Exit status: 0 CLEAN, 1 INTERCEPTION_PRESENT, 2 could not determine.
+
+    python3 scripts/openfut-interception-preflight.py
+    python3 scripts/openfut-interception-preflight.py --advertise 10.10.0.120
+"""
+from __future__ import annotations
+
+import argparse
+import re
+import shutil
+import socket
+import subprocess
+import sys
+
+# The endpoints a FIFA 17 client actually dials, plus the staging twins that
+# stale rules historically pointed at.
+PRODUCTION_PORTS = {
+    8099: "UTAS (Rust utas-host)",
+    8081: "roster",
+    8094: "POW api",
+    8085: "POW content",
+    4216: "LSX (client-side)",
+    42127: "Blaze redirector",
+    42130: "Blaze main",
+    42131: "Nucleus",
+}
+
+# LSX runs on the GAME machine, not here: the compose file publishes 4216 but
+# `OPENFUT_SERVERS` excludes lsx by default, so "published but not served" is
+# its normal state and must not be reported as interception. Every other port
+# above is expected to be served on this host.
+NOT_SERVED_HERE = {4216}
+STAGING_PORTS = {8299: "staging UTAS", 42327: "staging redirector",
+                 42330: "staging blaze main", 8281: "staging roster",
+                 18094: "staging POW", 18106: "retired season-shim"}
+ALL_PORTS = dict(PRODUCTION_PORTS)
+ALL_PORTS.update(STAGING_PORTS)
+
+
+def _run(cmd: list[str]) -> str:
+    try:
+        r = subprocess.run(cmd, capture_output=True, text=True, timeout=20)
+        return r.stdout
+    except Exception:
+        return ""
+
+
+def switch_status() -> tuple[str, list[str]]:
+    """`openfut-switch.sh status`, which owns the redirect lifecycle."""
+    for path in ("/home/alex/OpenFUT/openfut-blaze-host/openfut-switch.sh",
+                 "openfut-blaze-host/openfut-switch.sh"):
+        if shutil.which("bash") and subprocess.run(
+                ["test", "-x", path], capture_output=True).returncode == 0:
+            out = _run([path, "status"])
+            active = [l.strip() for l in out.splitlines()
+                      if "->" in l and "openfut-switch" in l]
+            return ("INACTIVE" if "INACTIVE" in out else
+                    ("ACTIVE" if active else "UNKNOWN")), active
+    return "UNKNOWN", []
+
+
+def nft_redirects(advertise: str) -> tuple[list[str], list[str]]:
+    """Split nft rules touching our ports into REDIRECTs (interception) and
+    Docker's own DNAT (legitimate publishing)."""
+    out = _run(["sudo", "-n", "nft", "list", "ruleset"])
+    if not out:
+        out = _run(["nft", "list", "ruleset"])
+    redirects, dnats = [], []
+    port_re = re.compile(r"dport (\d+)")
+    for line in out.splitlines():
+        s = line.strip()
+        m = port_re.search(s)
+        if not m or int(m.group(1)) not in ALL_PORTS:
+            continue
+        if "redirect to" in s:
+            redirects.append(s)
+        elif "dnat to" in s:
+            dnats.append(s)
+    return redirects, dnats
+
+
+def reachable(host: str, port: int, timeout: float = 2.0) -> bool:
+    s = socket.socket()
+    s.settimeout(timeout)
+    try:
+        s.connect((host, port))
+        return True
+    except OSError:
+        return False
+    finally:
+        s.close()
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--advertise", default="10.10.0.120",
+                    help="the address the CLIENT dials (not loopback)")
+    args = ap.parse_args()
+    adv = args.advertise
+
+    print("OpenFUT interception preflight — advertise=%s" % adv)
+    print()
+
+    state, active = switch_status()
+    print("openfut-switch : %s" % state)
+    for a in active:
+        print("   %s" % a)
+
+    redirects, dnats = nft_redirects(adv)
+    print("\nnft REDIRECTs on OpenFUT ports : %d%s"
+          % (len(redirects), "  <-- INTERCEPTION" if redirects else ""))
+    for r in redirects:
+        print("   %s" % r[:150])
+    print("nft DNAT (docker publishing)   : %d (expected, not interception)"
+          % len(dnats))
+
+    # The point of the whole tool: compare loopback with the address the client
+    # actually dials. A redirect keyed on the LAN IP is invisible to loopback.
+    print("\neffective endpoint, loopback vs advertised:")
+    disagree = []
+    for port, label in sorted(PRODUCTION_PORTS.items()):
+        lo = reachable("127.0.0.1", port)
+        wan = reachable(adv, port)
+        if lo == wan:
+            flag = ""
+        elif port in NOT_SERVED_HERE:
+            flag = "   (not served here -- expected)"
+        else:
+            flag = "   <-- DISAGREE"
+        if lo != wan and port not in NOT_SERVED_HERE:
+            disagree.append((port, label, lo, wan))
+        print("   :%-6d %-24s loopback=%-5s advertised=%-5s%s"
+              % (port, label, lo, wan, flag))
+
+    intercepted = bool(redirects) or state == "ACTIVE" or bool(disagree)
+    print()
+    if intercepted:
+        print("RESULT: INTERCEPTION_PRESENT")
+        if disagree:
+            print("  loopback and the advertised address disagree on: %s"
+                  % ", ".join(":%d" % p for p, _, _, _ in disagree))
+        print("  Nothing was changed. To clear a switch rule, run explicitly:")
+        print("    openfut-blaze-host/openfut-switch.sh off --name <id>")
+        return 1
+    print("RESULT: CLEAN")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())