diff --git a/hosting/docker-compose/ee/docker-compose.dev.yml b/hosting/docker-compose/ee/docker-compose.dev.yml
index b26c27e0cf..29ed893d43 100644
--- a/hosting/docker-compose/ee/docker-compose.dev.yml
+++ b/hosting/docker-compose/ee/docker-compose.dev.yml
@@ -424,6 +424,12 @@ services:
             AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS: ${AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS:-}
             AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM: ${AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM:-}
             AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES: ${AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES:-}
+            # This service has no env_file (see above), so the session flags must be listed
+            # here or they can never be set. AGENTA_SESSIONS_RECONSTRUCT must be enabled
+            # together with the web NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY, or a turn that
+            # carries only its last message loses the conversation.
+            AGENTA_SESSIONS_RECONSTRUCT: ${AGENTA_SESSIONS_RECONSTRUCT:-}
+            AGENTA_RECORDS_DURABLE: ${AGENTA_RECORDS_DURABLE:-}
         # === STORAGE ============================================== #
         volumes:
             - ../../../services/runner/src:/app/src
diff --git a/hosting/docker-compose/ee/docker-compose.gh.yml b/hosting/docker-compose/ee/docker-compose.gh.yml
index 2e71f84034..a27df46a02 100644
--- a/hosting/docker-compose/ee/docker-compose.gh.yml
+++ b/hosting/docker-compose/ee/docker-compose.gh.yml
@@ -295,6 +295,12 @@ services:
             AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS: ${AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS:-}
             AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM: ${AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM:-}
             AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES: ${AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES:-}
+            # This service has no env_file (see above), so the session flags must be listed
+            # here or they can never be set. AGENTA_SESSIONS_RECONSTRUCT must be enabled
+            # together with the web NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY, or a turn that
+            # carries only its last message loses the conversation.
+            AGENTA_SESSIONS_RECONSTRUCT: ${AGENTA_SESSIONS_RECONSTRUCT:-}
+            AGENTA_RECORDS_DURABLE: ${AGENTA_RECORDS_DURABLE:-}
         # === SUBSCRIPTION MOUNTS (opt-in) ========================= #
         # Use your own harness subscription for LOCAL runs instead of a managed API
         # key. Mount the login READ-WRITE: the harness runs directly out of the mount and
diff --git a/hosting/docker-compose/ee/env.ee.dev.example b/hosting/docker-compose/ee/env.ee.dev.example
index 0782fe2c74..94bea8b7b0 100644
--- a/hosting/docker-compose/ee/env.ee.dev.example
+++ b/hosting/docker-compose/ee/env.ee.dev.example
@@ -111,6 +111,18 @@ AGENTA_RUNNER_DEFAULT_SANDBOX_PROVIDER=local
 # 5 min per tool call.
 # AGENTA_RUNNER_TOOL_CALL_TIMEOUT_MS=300000
 
+# --- Session history: last-message-only turns (all four default off) ---
+# The client sends only the newest user message and the runner rebuilds the earlier turns
+# from the durable session record log, which keeps requests and traces small on a long
+# conversation. The first two must be flipped together: with the web flag on and the runner
+# flag off, a turn arrives with no history at all.
+# AGENTA_SESSIONS_RECONSTRUCT=true
+# NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY=true
+# Records become the only copy of the conversation, so make writing them durable and keep
+# the structure of a record whose body exceeds the API size cap.
+# AGENTA_RECORDS_DURABLE=true
+# AGENTA_RECORDS_SMART_TRUNCATION=true
+
 # ================================================================== #
 # Agenta - API
 # ================================================================== #
diff --git a/hosting/docker-compose/ee/env.ee.gh.example b/hosting/docker-compose/ee/env.ee.gh.example
index a8de6f8618..3cef8caad3 100644
--- a/hosting/docker-compose/ee/env.ee.gh.example
+++ b/hosting/docker-compose/ee/env.ee.gh.example
@@ -113,6 +113,18 @@ AGENTA_RUNNER_TOKEN=replace-me
 # 5 min per tool call.
 # AGENTA_RUNNER_TOOL_CALL_TIMEOUT_MS=300000
 
+# --- Session history: last-message-only turns (all four default off) ---
+# The client sends only the newest user message and the runner rebuilds the earlier turns
+# from the durable session record log, which keeps requests and traces small on a long
+# conversation. The first two must be flipped together: with the web flag on and the runner
+# flag off, a turn arrives with no history at all.
+# AGENTA_SESSIONS_RECONSTRUCT=true
+# NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY=true
+# Records become the only copy of the conversation, so make writing them durable and keep
+# the structure of a record whose body exceeds the API size cap.
+# AGENTA_RECORDS_DURABLE=true
+# AGENTA_RECORDS_SMART_TRUNCATION=true
+
 # ================================================================== #
 # Agenta - API
 # ================================================================== #
diff --git a/hosting/docker-compose/oss/docker-compose.dev.yml b/hosting/docker-compose/oss/docker-compose.dev.yml
index 604d62bfa1..b178dfe07d 100644
--- a/hosting/docker-compose/oss/docker-compose.dev.yml
+++ b/hosting/docker-compose/oss/docker-compose.dev.yml
@@ -410,6 +410,12 @@ services:
             AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS: ${AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS:-}
             AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM: ${AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM:-}
             AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES: ${AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES:-}
+            # This service has no env_file (see above), so the session flags must be listed
+            # here or they can never be set. AGENTA_SESSIONS_RECONSTRUCT must be enabled
+            # together with the web NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY, or a turn that
+            # carries only its last message loses the conversation.
+            AGENTA_SESSIONS_RECONSTRUCT: ${AGENTA_SESSIONS_RECONSTRUCT:-}
+            AGENTA_RECORDS_DURABLE: ${AGENTA_RECORDS_DURABLE:-}
         # === STORAGE ============================================== #
         volumes:
             - ../../../services/runner/src:/app/src
diff --git a/hosting/docker-compose/oss/docker-compose.gh.yml b/hosting/docker-compose/oss/docker-compose.gh.yml
index a9777adfa9..09f9f0e802 100644
--- a/hosting/docker-compose/oss/docker-compose.gh.yml
+++ b/hosting/docker-compose/oss/docker-compose.gh.yml
@@ -312,6 +312,12 @@ services:
             AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS: ${AGENTA_RUNNER_DAYTONA_SESSION_IDLE_TTL_MS:-}
             AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM: ${AGENTA_RUNNER_DAYTONA_SESSION_MAX_WARM:-}
             AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES: ${AGENTA_RUNNER_DAYTONA_AUTODELETE_MINUTES:-}
+            # This service has no env_file (see above), so the session flags must be listed
+            # here or they can never be set. AGENTA_SESSIONS_RECONSTRUCT must be enabled
+            # together with the web NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY, or a turn that
+            # carries only its last message loses the conversation.
+            AGENTA_SESSIONS_RECONSTRUCT: ${AGENTA_SESSIONS_RECONSTRUCT:-}
+            AGENTA_RECORDS_DURABLE: ${AGENTA_RECORDS_DURABLE:-}
         # === SUBSCRIPTION MOUNTS (opt-in) ========================= #
         # Use your own harness subscription for LOCAL runs instead of a managed API
         # key. Mount the login READ-WRITE: the harness runs directly out of the mount and
diff --git a/hosting/docker-compose/oss/env.oss.dev.example b/hosting/docker-compose/oss/env.oss.dev.example
index b75eb975e1..37e70a43c1 100644
--- a/hosting/docker-compose/oss/env.oss.dev.example
+++ b/hosting/docker-compose/oss/env.oss.dev.example
@@ -111,6 +111,18 @@ AGENTA_RUNNER_DEFAULT_SANDBOX_PROVIDER=local
 # 5 min per tool call.
 # AGENTA_RUNNER_TOOL_CALL_TIMEOUT_MS=300000
 
+# --- Session history: last-message-only turns (all four default off) ---
+# The client sends only the newest user message and the runner rebuilds the earlier turns
+# from the durable session record log, which keeps requests and traces small on a long
+# conversation. The first two must be flipped together: with the web flag on and the runner
+# flag off, a turn arrives with no history at all.
+# AGENTA_SESSIONS_RECONSTRUCT=true
+# NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY=true
+# Records become the only copy of the conversation, so make writing them durable and keep
+# the structure of a record whose body exceeds the API size cap.
+# AGENTA_RECORDS_DURABLE=true
+# AGENTA_RECORDS_SMART_TRUNCATION=true
+
 # ================================================================== #
 # Agenta - API
 # ================================================================== #
diff --git a/hosting/docker-compose/oss/env.oss.gh.example b/hosting/docker-compose/oss/env.oss.gh.example
index 7cf53d9c10..dfa65636ea 100644
--- a/hosting/docker-compose/oss/env.oss.gh.example
+++ b/hosting/docker-compose/oss/env.oss.gh.example
@@ -113,6 +113,18 @@ AGENTA_RUNNER_TOKEN=replace-me
 # 5 min per tool call.
 # AGENTA_RUNNER_TOOL_CALL_TIMEOUT_MS=300000
 
+# --- Session history: last-message-only turns (all four default off) ---
+# The client sends only the newest user message and the runner rebuilds the earlier turns
+# from the durable session record log, which keeps requests and traces small on a long
+# conversation. The first two must be flipped together: with the web flag on and the runner
+# flag off, a turn arrives with no history at all.
+# AGENTA_SESSIONS_RECONSTRUCT=true
+# NEXT_PUBLIC_SESSIONS_LAST_MESSAGE_ONLY=true
+# Records become the only copy of the conversation, so make writing them durable and keep
+# the structure of a record whose body exceeds the API size cap.
+# AGENTA_RECORDS_DURABLE=true
+# AGENTA_RECORDS_SMART_TRUNCATION=true
+
 # ================================================================== #
 # Agenta - API
 # ================================================================== #