diff --git a/fifa17-recon/docs/CLIENT_ROUTE_SURFACE.md b/fifa17-recon/docs/CLIENT_ROUTE_SURFACE.md
index 20bedd4..1ebe243 100644
--- a/fifa17-recon/docs/CLIENT_ROUTE_SURFACE.md
+++ b/fifa17-recon/docs/CLIENT_ROUTE_SURFACE.md
@@ -300,3 +300,64 @@ Unresolved, and NOT to be guessed: the fcc tables are loaded by `FIFA17.exe`, no
 CardsDLL (the table-name and column literals are absent from the DLL), so the
 reader that would settle amount-vs-weight lives in the EXE. Status stays
 **EFFECT_UNKNOWN**.
+
+## Post-ACK behaviour — OUTCOME B, LIVE_PROVEN (2026-08-22)
+
+Captured with the staging probe answering `200 {"itemData":[]}` and mutating
+nothing:
+
+```
+T0  POST /ut/game/fifa17/item/resource/5001004   {"apply":[{"id":100000003}]}
+T1  200 {"itemData":[]}
+T2  callback -> SUCCESS   (no failure event; ZERO ut/delete/auth; session alive)
+T4  GET club/consumables/contracts     <- refresh of the SOURCE list
+T5  GET club/consumables/development
+T6  GET squad/active                   <- refresh of the TARGET
+T7  no second mutation of any kind
+```
+
+So of the candidate protocols:
+
+```
+B)  POST resource -> ACK -> client performs GET refresh
+                         -> the SERVER is expected to have mutated state
+```
+
+Ruled out by observation: (A) the response carries the modified state — the body
+was empty and the client was satisfied; (C) a follow-up generic PUT/item — none
+was sent; (D) another route performs the mutation — nothing else was called.
+
+Three consequences.
+
+1. **The success verdict is transport-only, confirmed live.** The static read of
+   `0x180035520` said the body is never inspected; an empty `itemData` produced a
+   clean success and a surviving session, which is that prediction holding.
+2. **The server owns the effect entirely.** The client does not compute one; it
+   re-reads. This is the good failure mode: a wrong server-side effect cannot be
+   masked by client-side optimism, and the refresh will always show server truth.
+   Here the refresh correctly showed `contracts copies=3` and an unchanged squad,
+   because the probe consumed nothing.
+3. **There is no client-side amount to harvest.** Since the client never renders
+   an optimistic "+N games" of its own, the live path cannot reveal the grant
+   size. The number the client DISPLAYS on a contract card comes from the wire
+   `contract` atom (0xb8 -> record+0x8c; see `fut_consumables.py`, which notes
+   categories 2 and 3 ignore `amount` and read `contract`) — i.e. the server
+   tells the client what the card is worth.
+
+That last point matters for honesty: our oracle has been sending the placeholder
+`7` for that atom, so every contract card this project has ever shown a player
+said "7" because WE said 7. Recovering EA's real value is not reachable from the
+client's behaviour; it needs the `FIFA17.exe` reader of `fcc_contractcards`, or
+it becomes an explicit design decision. Status: **EFFECT_UNKNOWN**.
+
+### Boundary status
+
+| aspect | status |
+|---|---|
+| route, method, source encoding, target encoding | LIVE_PROVEN |
+| success condition (`[obj+0x1c] == 0`, body ignored) | STATIC_REVERSED + LIVE_CONFIRMED |
+| response shape accepted by the client | LIVE_PROVEN (`{"itemData":[]}`, session survived) |
+| post-ACK protocol | LIVE_PROVEN — outcome B |
+| batching | UNPROVEN — refused, never guessed |
+| contract effect / grant size | UNKNOWN (placeholder source refuted) |
+| source instance selection with multiple copies | UNDETERMINED (only 1 copy owned) |