diff --git a/PROJECT_CONTEXT.md b/PROJECT_CONTEXT.md
index 1d4bcdb..4ce8dc5 100644
--- a/PROJECT_CONTEXT.md
+++ b/PROJECT_CONTEXT.md
@@ -167,6 +167,10 @@ The detailed architecture, controls and stopping gates for P3 are frozen in
 - EasyCom targets are dense `[T, 3]`; predictions are
   `[target_time, class, future_horizon]`.
 - EasyCom split: train Session 4--12; test Session 1--3.
+- Locked final head protocol: exactly 4 epochs on all Sessions 4--12, no
+  development checkpoint selection, followed by one evaluation on Sessions
+  1--3. Historical Session-12 screens remain development diagnostics and are
+  not the final training protocol.
 
 ### Global feature sidecar
 
diff --git a/docs/easycom_oracle_information.md b/docs/easycom_oracle_information.md
index 5bb4999..5f34ab3 100644
--- a/docs/easycom_oracle_information.md
+++ b/docs/easycom_oracle_information.md
@@ -71,17 +71,39 @@ Sessions 1--3.
 If preparation reports any transcript/target mismatch, stop and inspect it;
 the preparation command has no mismatch-tolerance option.
 
+## Locked four-epoch train-all protocol
+
+The final protocol fixes the training budget at four epochs, trains on all
+official EasyCom training sessions (Sessions 4--12), performs no development
+checkpoint selection, and evaluates Sessions 1--3 once:
+
+```bash
+CUDA_VISIBLE_DEVICES=0 bash run_easycom_oracle_information.sh final 0 1 2
+```
+
+The `final` stage enforces `EPOCHS=4` and exactly Sessions 4--12, clears the
+development-session list internally, and saves the last epoch. Its artifacts
+use separate `_train4_12_fixed4` checkpoint/result roots by default, so they
+cannot overwrite the historical Session-12 development screen. Override those
+roots only with `FINAL_CHECKPOINT_ROOT` and `FINAL_RESULT_ROOT`.
+
+mAP itself does not require threshold calibration. Nevertheless, the official
+test results must not be used to choose a variant, epoch, loss, fusion design,
+or any later hyperparameter. Run `final` only after those decisions are frozen;
+repeatedly inspecting Sessions 1--3 and modifying the method would contaminate
+the official test split.
+
 ## Follow-up
 
-If `per-person` is consistently better on Session 12, add seeds 1 and 2 using
-the already prepared sidecars:
+To reproduce the historical Session-12 development screen for seeds 1 and 2,
+use the already prepared sidecars:
 
 ```bash
 CUDA_VISIBLE_DEVICES=0 bash run_easycom_oracle_information.sh screen 1 2
 ```
 
-Only after freezing the method and event evaluator should selected variants be
-run once on Sessions 1--3:
+The older two-stage equivalent of final test inference is retained for
+reproducibility, but the locked protocol above is preferred for new final runs:
 
 ```bash
 VARIANTS="audio aggregate-visible per-person shuffled-id delayed" \
diff --git a/run_easycom_oracle_information.sh b/run_easycom_oracle_information.sh
index 0a19aae..8fae88f 100755
--- a/run_easycom_oracle_information.sh
+++ b/run_easycom_oracle_information.sh
@@ -72,18 +72,13 @@ variant_local_args() {
   fi
 }
 
-train_and_screen() {
+train_variants() {
   mkdir -p "${CHECKPOINT_ROOT}" "${RESULT_ROOT}"
   for seed in "${seeds[@]}"; do
     for variant in "${variants[@]}"; do
       checkpoint="${CHECKPOINT_ROOT}/${variant}_seed${seed}.pth"
-      result="${RESULT_ROOT}/${variant}_seed${seed}"
-      local_feature_root="${ORACLE_ROOT}/${variant}"
-      if [[ "${variant}" == "audio" ]]; then
-        local_feature_root="${LOCAL_ROOT}"
-      fi
-      if [[ -e "${checkpoint}" || -e "${result}" ]]; then
-        echo "Refusing to overwrite ${checkpoint} or ${result}" >&2
+      if [[ -e "${checkpoint}" ]]; then
+        echo "Refusing to overwrite ${checkpoint}" >&2
         exit 1
       fi
       local_args=()
@@ -111,7 +106,28 @@ train_and_screen() {
         --expected-mode "${EXPECTED_MODE}" \
         --seed "${seed}" \
         --device cuda:0
+    done
+  done
+}
 
+screen_variants() {
+  mkdir -p "${RESULT_ROOT}"
+  for seed in "${seeds[@]}"; do
+    for variant in "${variants[@]}"; do
+      checkpoint="${CHECKPOINT_ROOT}/${variant}_seed${seed}.pth"
+      result="${RESULT_ROOT}/${variant}_seed${seed}"
+      local_feature_root="${ORACLE_ROOT}/${variant}"
+      if [[ "${variant}" == "audio" ]]; then
+        local_feature_root="${LOCAL_ROOT}"
+      fi
+      if [[ ! -f "${checkpoint}" ]]; then
+        echo "Missing checkpoint: ${checkpoint}" >&2
+        exit 1
+      fi
+      if [[ -e "${result}" ]]; then
+        echo "Refusing to overwrite ${result}" >&2
+        exit 1
+      fi
       echo "$(date): screening ${variant}, seed=${seed} on ${screen_sessions[*]}"
       "${PYTHON_BIN}" infer_turn_head.py \
         --feature-root "${FEATURE_ROOT}" \
@@ -130,6 +146,30 @@ train_and_screen() {
     --protocol causal_valid_only
 }
 
+train_all_fixed_and_test() {
+  if [[ "${EPOCHS}" != "4" ]]; then
+    echo "The final protocol requires EPOCHS=4, got ${EPOCHS}" >&2
+    exit 2
+  fi
+
+  normalized_train=()
+  for session in "${train_sessions[@]}"; do
+    normalized_train+=("${session#Session_}")
+  done
+  if [[ "${normalized_train[*]}" != "4 5 6 7 8 9 10 11 12" ]]; then
+    echo "The final protocol requires exactly EasyCom Sessions 4--12 for training" >&2
+    exit 2
+  fi
+
+  # No development checkpoint selection: the final epoch is fixed in advance.
+  # Keep these artifacts separate from the historical Session-12 screen.
+  dev_sessions=()
+  CHECKPOINT_ROOT="${FINAL_CHECKPOINT_ROOT:-${CHECKPOINT_ROOT}_train4_12_fixed4}"
+  RESULT_ROOT="${FINAL_RESULT_ROOT:-${RESULT_ROOT}_train4_12_fixed4}"
+  train_variants
+  test_selected
+}
+
 test_selected() {
   mkdir -p "${RESULT_ROOT}_test"
   for seed in "${seeds[@]}"; do
@@ -170,11 +210,17 @@ case "${stage}" in
     prepare_oracles
     ;;
   screen)
-    train_and_screen
+    train_variants
+    screen_variants
     ;;
   all)
     prepare_oracles
-    train_and_screen
+    train_variants
+    screen_variants
+    ;;
+  final)
+    prepare_oracles
+    train_all_fixed_and_test
     ;;
   test)
     test_selected
@@ -186,7 +232,7 @@ case "${stage}" in
       --protocol causal_valid_only
     ;;
   *)
-    echo "Usage: $0 {prepare|screen|all|test|summarize} [seed ...]" >&2
+    echo "Usage: $0 {prepare|screen|all|final|test|summarize} [seed ...]" >&2
     exit 2
     ;;
 esac