diff --git a/crates/loopd/tests/device.rs b/crates/loopd/tests/device.rs
index 61793c6..58d167b 100644
--- a/crates/loopd/tests/device.rs
+++ b/crates/loopd/tests/device.rs
@@ -59,6 +59,13 @@ impl Drop for Proxy {
     }
 }
 
+/// The server as deployed on straylight, recorded in one place. When the deployment changes on
+/// purpose, change this and `tools/check-m3a-device.sh` together, and note it in
+/// `docs/inference-contract.md`. Since 2026-09-22: four slots over one 262,144-token pool.
+const EXPECT: &str = r#"template_sha256 = "f55f52930aa8bf44ab5cb85f99370fcc3c56e9a85640b812086d5330bce5d86b"
+n_ctx = 262144
+slots = 4"#;
+
 fn socket_path(name: &str) -> PathBuf {
     let dir = std::env::temp_dir().join(format!("loopd-device-{}-{name}", std::process::id()));
     std::fs::create_dir_all(&dir).unwrap();
@@ -77,9 +84,7 @@ model = "{model}"
 main = 0
 background = 1
 [expect]
-template_sha256 = "f55f52930aa8bf44ab5cb85f99370fcc3c56e9a85640b812086d5330bce5d86b"
-n_ctx = 131072
-slots = 2
+{EXPECT}
 "#,
         socket.display()
     );
@@ -253,9 +258,7 @@ model = "{model}"
 main = 0
 background = 1
 [expect]
-template_sha256 = "f55f52930aa8bf44ab5cb85f99370fcc3c56e9a85640b812086d5330bce5d86b"
-n_ctx = 131072
-slots = 2
+{EXPECT}
 [paths]
 home = "{}"
 "#,
diff --git a/docs/inference-contract.md b/docs/inference-contract.md
index bad95ca..6ef6871 100644
--- a/docs/inference-contract.md
+++ b/docs/inference-contract.md
@@ -10,6 +10,25 @@ the server README at tag `b10809`, the build that is running.
 not affected by that. Throughput is, so section (a) reports a separate run taken after the GPU went
 idle. Section (d) was also run with the GPU idle.
 
+## Deployment change, 2026-09-20
+
+Found in the M3a review on 2026-09-22, when `loopd`'s self-test refused the server
+(`context per slot: expected 131072, got 262144`). The owner changed Ornith's preset in
+`~/src/nixos/hw/straylight/default.nix` after measuring prompt-cache thrash between OpenCode, Hermes
+and its subagents on two slots:
+
+- `parallel = 4` with `kv-unified = true`: four slots share one 262,144-token KV pool. Any one
+  session may use the whole pool while the others are idle.
+- A 16 GiB host prompt cache (was 8 GiB), `--models-max 3`, and a server-side
+  `reasoning-budget = 8192`.
+
+Not re-measured yet. Two findings above rest on the old layout and need checking before M3b or M5
+leans on them: (d), that a second session on another slot leaves the first slot's cache intact,
+now that the slots share one pool; and P9's picture of eviction, where another client's long
+prompt can now crowd a harness session out of the pool without touching its slot. The harness's
+own expectations (`crates/loopd/tests/device.rs`, `tools/check-m3a-device.sh`) record the new
+layout; `make verify-device` passes against it (6 of 6, 2026-09-22).
+
 ## What is running
 
 | Item | Value |
@@ -19,7 +38,7 @@ idle. Section (d) was also run with the GPU idle.
 | Public listener | `0.0.0.0:11434`, firewalled to the tailnet; Tailscale Serve adds HTTPS on `:10000` |
 | Other clients | Open WebUI and OpenCode use the same endpoint and the same Ornith instance |
 | Ornith flags | `--jinja --no-mmap --ctx-size 262144 --parallel 2 --cache-type-k q8_0 --cache-type-v q8_0 --flash-attn on --n-gpu-layers 999 --sleep-idle-seconds 21600 --hf-repo ornith-ai/Ornith-1.5-35B-A3B-GGUF:Q4_K_M` |
-| Slots | 2, each `n_ctx` 131072 (the 262144 is split, not shared) |
+| Slots | Until 2026-09-20: 2, each `n_ctx` 131072 (the 262144 split, not shared). Since then: 4 over one unified 262144-token pool (`kv-unified`); `/props` reports `n_ctx` 262144 per slot. See "Deployment change, 2026-09-20" |
 | Server default sampling | temperature 1.0, top_k 20, top_p 0.95, min_p 0.05. The harness must send its own. |
 | Chat template | 7,828 bytes, sha256 `f55f52930aa8bf44ab5cb85f99370fcc3c56e9a85640b812086d5330bce5d86b` |
 | Source of truth for flags | `~/src/nixos/hw/straylight/default.nix` on straylight, not this repo |
diff --git a/tools/check-m3a-device.sh b/tools/check-m3a-device.sh
index e5cd69c..d5e960a 100755
--- a/tools/check-m3a-device.sh
+++ b/tools/check-m3a-device.sh
@@ -84,8 +84,8 @@ main = 0
 background = 1
 [expect]
 template_sha256 = "f55f52930aa8bf44ab5cb85f99370fcc3c56e9a85640b812086d5330bce5d86b"
-n_ctx = 131072
-slots = 2
+n_ctx = 262144
+slots = 4
 [paths]
 home = "$HOME_DIR"
 [broker]