diff --git a/lib/mod/conformance.conf b/lib/mod/conformance.conf
index e558811f..ee19cec8 100644
--- a/lib/mod/conformance.conf
+++ b/lib/mod/conformance.conf
@@ -22,6 +22,7 @@ PRELOADS=(
   lib/mod/batch.sx
   lib/mod/temporal.sx
   lib/mod/sla.sx
+  lib/mod/wire.sx
   lib/mod/lifecycle.sx
   lib/mod/audit.sx
   lib/mod/api.sx
@@ -46,4 +47,5 @@ SUITES=(
   "batch:lib/mod/tests/batch.sx:(mod-batch-tests-run!)"
   "temporal:lib/mod/tests/temporal.sx:(mod-temporal-tests-run!)"
   "sla:lib/mod/tests/sla.sx:(mod-sla-tests-run!)"
+  "wire:lib/mod/tests/wire.sx:(mod-wire-tests-run!)"
 )
diff --git a/lib/mod/scoreboard.json b/lib/mod/scoreboard.json
index 97f2beb8..005313c5 100644
--- a/lib/mod/scoreboard.json
+++ b/lib/mod/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "lang": "mod",
-  "total_passed": 307,
+  "total_passed": 323,
   "total_failed": 0,
-  "total": 307,
+  "total": 323,
   "suites": [
     {"name":"decide","passed":31,"failed":0,"total":31},
     {"name":"audit","passed":29,"failed":0,"total":29},
@@ -18,7 +18,8 @@
     {"name":"whatif","passed":13,"failed":0,"total":13},
     {"name":"batch","passed":17,"failed":0,"total":17},
     {"name":"temporal","passed":15,"failed":0,"total":15},
-    {"name":"sla","passed":15,"failed":0,"total":15}
+    {"name":"sla","passed":15,"failed":0,"total":15},
+    {"name":"wire","passed":16,"failed":0,"total":16}
   ],
-  "generated": "2026-06-06T19:08:06+00:00"
+  "generated": "2026-06-06T19:16:49+00:00"
 }
diff --git a/lib/mod/scoreboard.md b/lib/mod/scoreboard.md
index 680ef546..21b21cf7 100644
--- a/lib/mod/scoreboard.md
+++ b/lib/mod/scoreboard.md
@@ -1,6 +1,6 @@
 # mod scoreboard
 
-**307 / 307 passing** (0 failure(s)).
+**323 / 323 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -19,3 +19,4 @@
 | batch | 17 | 17 | ok |
 | temporal | 15 | 15 | ok |
 | sla | 15 | 15 | ok |
+| wire | 16 | 16 | ok |
diff --git a/lib/mod/tests/wire.sx b/lib/mod/tests/wire.sx
new file mode 100644
index 00000000..fd070a67
--- /dev/null
+++ b/lib/mod/tests/wire.sx
@@ -0,0 +1,96 @@
+;; lib/mod/tests/wire.sx — Ext 14: decision wire format + federated transport.
+
+(define mod-w-count 0)
+(define mod-w-pass 0)
+(define mod-w-fail 0)
+(define mod-w-failures (list))
+
+(define
+  mod-w-test!
+  (fn
+    (name got expected)
+    (begin
+      (set! mod-w-count (+ mod-w-count 1))
+      (if
+        (= got expected)
+        (set! mod-w-pass (+ mod-w-pass 1))
+        (begin
+          (set! mod-w-fail (+ mod-w-fail 1))
+          (append!
+            mod-w-failures
+            (str name "\n    expected: " expected "\n    got:      " got)))))))
+
+;; ── split-char ──
+
+(mod-w-test! "split on pipe" (mod/split-char "a|b|c" "|") (list "a" "b" "c"))
+(mod-w-test! "split single field" (mod/split-char "abc" "|") (list "abc"))
+(mod-w-test!
+  "split four fields"
+  (len (mod/split-char "MOD1|r1|hide|spam-hide" "|"))
+  4)
+
+;; ── serialize ──
+
+(define
+  mod-w-dec
+  (mod/decide-report
+    (mod/mk-report "r1" "a" "bob" "this is spam")
+    (list (mod/mk-report "r1" "a" "bob" "this is spam"))
+    mod/default-rules))
+(define mod-w-line (mod/decision->wire mod-w-dec))
+
+(mod-w-test!
+  "wire is versioned + delimited"
+  mod-w-line
+  "MOD1|r1|hide|spam-hide")
+(mod-w-test!
+  "wire-valid? accepts well-formed"
+  (mod/wire-valid? mod-w-line)
+  true)
+(mod-w-test!
+  "wire-valid? rejects junk"
+  (mod/wire-valid? "not a wire line")
+  false)
+(mod-w-test!
+  "wire-valid? rejects wrong version"
+  (mod/wire-valid? "MOD9|r1|hide|x")
+  false)
+
+;; ── round-trip ──
+
+(define mod-w-back (mod/wire->decision mod-w-line))
+(mod-w-test! "round-trip report-id" (get mod-w-back :report-id) "r1")
+(mod-w-test! "round-trip action" (get mod-w-back :action) "hide")
+(mod-w-test! "round-trip rule" (get mod-w-back :rule) "spam-hide")
+(mod-w-test! "round-trip tags :wire" (get mod-w-back :wire) true)
+(mod-w-test! "malformed → nil" (mod/wire->decision "garbage") nil)
+
+;; ── full federated transport: serialize → wire → deserialize → trust-gate ──
+
+(mod/fed-reset!)
+(define mod-w-peer-dec (mod/wire->decision mod-w-line))
+
+;; untrusted peer: decision is advisory, not applied
+(define mod-w-recv1 (mod/fed-receive-decision "peerX" mod-w-peer-dec))
+(mod-w-test!
+  "wired decision from untrusted peer → advisory"
+  (get mod-w-recv1 :applied)
+  false)
+(mod-w-test!
+  "untrusted wired decision not applied locally"
+  (mod/fed-applied-action "r1")
+  nil)
+
+;; trusted peer: decision binds locally
+(mod/grant-trust "peerY" :mod)
+(define mod-w-recv2 (mod/fed-receive-decision "peerY" mod-w-peer-dec))
+(mod-w-test!
+  "wired decision from trusted peer → applied"
+  (get mod-w-recv2 :applied)
+  true)
+(mod-w-test!
+  "trusted wired decision binds locally"
+  (get (mod/fed-applied-action "r1") :action)
+  "hide")
+
+(define mod-wire-tests-run! (fn () {:failures mod-w-failures :total mod-w-count :passed mod-w-pass :failed mod-w-fail}))
diff --git a/lib/mod/wire.sx b/lib/mod/wire.sx
new file mode 100644
index 00000000..6ed0ef85
--- /dev/null
+++ b/lib/mod/wire.sx
@@ -0,0 +1,55 @@
+;; lib/mod/wire.sx — portable decision wire format for federation transport.
+;;
+;; fed.sx shares decisions as in-memory dicts and leaves mod/fed-send! as the
+;; transport seam. This is the bytes that cross it: a versioned, pipe-delimited
+;; line encoding the verdict a peer needs (report id, action, rule) — enough to
+;; trust-gate and apply/advise, without shipping the whole proof tree. The
+;; loaded env has no string split, so split is built over slice/len.
+
+(define
+  mod/split-loop
+  (fn
+    (s ch n start pos acc)
+    (if
+      (= pos n)
+      (append acc (list (slice s start n)))
+      (if
+        (= (slice s pos (+ pos 1)) ch)
+        (mod/split-loop
+          s
+          ch
+          n
+          (+ pos 1)
+          (+ pos 1)
+          (append acc (list (slice s start pos))))
+        (mod/split-loop s ch n start (+ pos 1) acc)))))
+
+(define
+  mod/split-char
+  (fn (s ch) (mod/split-loop s ch (len s) 0 0 (list))))
+
+(define
+  mod/decision->wire
+  (fn
+    (d)
+    (str "MOD1|" (get d :report-id) "|" (get d :action) "|" (get d :rule))))
+
+(define
+  mod/wire-valid?
+  (fn
+    (w)
+    (let
+      ((parts (mod/split-char w "|")))
+      (if
+        (= (len parts) 4)
+        (= (nth parts 0) "MOD1")
+        false))))
+
+(define
+  mod/wire->decision
+  (fn
+    (w)
+    (if
+      (mod/wire-valid? w)
+      (let ((parts (mod/split-char w "|"))) {:action (nth parts 2) :wire true :rule (nth parts 3) :report-id (nth parts 1)})
+      nil)))
diff --git a/plans/mod-on-sx.md b/plans/mod-on-sx.md
index 742919eb..3595a15d 100644
--- a/plans/mod-on-sx.md
+++ b/plans/mod-on-sx.md
@@ -16,7 +16,7 @@ federation extension.
 
 ## Status (rolling)
 
-`bash lib/mod/conformance.sh` → **307/307** (roadmap + 13 extensions complete)
+`bash lib/mod/conformance.sh` → **323/323** (roadmap + 14 extensions complete)
 
 ## Ground rules
 
@@ -147,6 +147,12 @@ lib/mod/fed.sx
   derivation goal-by-goal with `[proved]`/`[unproved]` marks and unification
   bindings. E.g. `Report rc: escalate (rule: repeated-escalate)` … `[proved]
   report(rc, B, S), report_count(S, N), N >= 3  {B=ann, N=3, S=dave}`.
+- [x] **Ext 14 — decision wire format** (`lib/mod/wire.sx`, +16). The bytes that
+  cross `fed/fed-send!`: `mod/decision->wire` emits a versioned pipe-delimited line
+  (`MOD1|r1|hide|spam-hide`), `mod/wire->decision` parses it back (`mod/wire-valid?`
+  guards). Built `mod/split-char` over `slice`/`len` (loaded env has no split).
+  Integration test exercises the full path: serialize → wire → deserialize →
+  `fed-receive-decision` trust-gating (untrusted→advisory, trusted→applied).
 - [x] **Ext 13 — SLA sweep over pending cases** (`lib/mod/sla.sx`, +15). Composes
   lifecycle (Phase 3) with time (Ext 12): a timed-case pairs a case with the tick
   it entered its state; `mod/overdue?` flags pending cases (open/triaged/appealed)
@@ -207,6 +213,11 @@ lib/mod/fed.sx
 
 ## Progress log
 
+- **Ext 14 — decision wire format, 323/323** (+16). Fills the federation transport
+  seam: decisions now serialize to a portable line and parse back, and the
+  integration test runs the whole federated path end-to-end (serialize on one
+  instance → trust-gated apply on another). Needed a hand-rolled `split-char`
+  (loaded env has no split) — over `slice`/`len`, same toolkit as `str-contains?`.
 - **Ext 13 — SLA sweep, 307/307** (+15). Two subsystems compose cleanly: lifecycle
   states + temporal ticks → "which pending cases have sat too long". Kept lifecycle
   pure by having the SLA layer carry entry-time externally (timed-case wrapper)