Rename compaction callsite enum and exhaustively match reinjection

codex-rs/core/src/codex.rs

@@ -19,7 +19,7 @@ use crate::analytics_client::build_track_events_context;
 use crate::apps::render_apps_section;
 use crate::commit_attribution::commit_message_trailer_instruction;
 use crate::compact;
-use crate::compact::AutoCompactCallsite;
+use crate::compact::CompactCallsite;
 use crate::compact::run_inline_auto_compact_task;
 use crate::compact::should_use_remote_compact_task;
 use crate::compact_remote::run_inline_remote_auto_compact_task;
@@ -4517,7 +4517,7 @@ pub(crate) async fn run_turn(
                     if let Err(err) = run_auto_compact(
                         &sess,
                         &turn_context,
-                        AutoCompactCallsite::MidTurnContinuation,
+                        CompactCallsite::MidTurnContinuation,
                         None,
                     )
                     .await
@@ -4670,7 +4670,7 @@ async fn maybe_run_previous_model_inline_compact(
         sess,
         // We use previous turn context here because we compact with the previous model
         &previous_turn_context,
-        AutoCompactCallsite::PreSamplingModelSwitch,
+        CompactCallsite::PreSamplingModelSwitch,
         None,
     )
     .await
@@ -4784,7 +4784,7 @@ async fn run_pre_turn_auto_compaction_if_needed(
     let compact_result = run_auto_compact(
         sess,
         turn_context,
-        AutoCompactCallsite::PreTurnIncludingIncomingUserMessage,
+        CompactCallsite::PreTurnIncludingIncomingUserMessage,
         Some(incoming_turn_items.to_vec()),
     )
     .await;
@@ -4803,7 +4803,7 @@ async fn run_pre_turn_auto_compaction_if_needed(
             CodexErr::ContextWindowExceeded => {
                 error!(
                     turn_id = %turn_context.sub_id,
-                    auto_compact_callsite = ?AutoCompactCallsite::PreTurnIncludingIncomingUserMessage,
+                    auto_compact_callsite = ?CompactCallsite::PreTurnIncludingIncomingUserMessage,
                     incoming_items_tokens_estimate,
                     auto_compact_limit,
                     reason = "pre-turn compaction exceeded context window",
@@ -4859,7 +4859,7 @@ fn is_projected_submission_over_auto_compact_limit(
 async fn run_auto_compact(
     sess: &Arc<Session>,
     turn_context: &Arc<TurnContext>,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     let result = if should_use_remote_compact_task(&turn_context.provider) {

codex-rs/core/src/compact.rs

@@ -35,7 +35,9 @@ pub const SUMMARY_PREFIX: &str = include_str!("../templates/compact/summary_pref
 const COMPACT_USER_MESSAGE_MAX_TOKENS: usize = 20_000;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) enum AutoCompactCallsite {
+pub(crate) enum CompactCallsite {
+    /// Manual `/compact` task.
+    ManualCompact,
     /// Pre-turn auto-compaction where the incoming turn context + user message are included in
     /// the compaction request.
     PreTurnIncludingIncomingUserMessage,
@@ -94,7 +96,7 @@ pub(crate) fn extract_latest_model_switch_update_from_items(
 pub(crate) async fn run_inline_auto_compact_task(
     sess: Arc<Session>,
     turn_context: Arc<TurnContext>,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     let prompt = turn_context.compact_prompt().to_string();
@@ -108,7 +110,7 @@ pub(crate) async fn run_inline_auto_compact_task(
         sess,
         turn_context,
         input,
-        Some(auto_compact_callsite),
+        auto_compact_callsite,
         incoming_items,
     )
     .await?;
@@ -126,14 +128,21 @@ pub(crate) async fn run_compact_task(
         collaboration_mode_kind: turn_context.collaboration_mode.mode,
     });
     sess.send_event(&turn_context, start_event).await;
-    run_compact_task_inner(sess, turn_context, input, None, None).await
+    run_compact_task_inner(
+        sess,
+        turn_context,
+        input,
+        CompactCallsite::ManualCompact,
+        None,
+    )
+    .await
 }
 
 async fn run_compact_task_inner(
     sess: Arc<Session>,
     turn_context: Arc<TurnContext>,
     input: Vec<UserInput>,
-    auto_compact_callsite: Option<AutoCompactCallsite>,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     let compaction_item = TurnItem::ContextCompaction(ContextCompactionItem::new());
@@ -285,14 +294,22 @@ async fn run_compact_task_inner(
         COMPACT_USER_MESSAGE_MAX_TOKENS,
     );
     let mut new_history = process_compacted_history(compacted_history);
-    if matches!(
-        auto_compact_callsite,
-        Some(
-            AutoCompactCallsite::MidTurnContinuation | AutoCompactCallsite::PreSamplingModelSwitch
-        )
-    ) {
-        let initial_context = sess.build_initial_context(turn_context.as_ref()).await;
-        insert_initial_context_before_last_real_user(&mut new_history, initial_context);
+    match auto_compact_callsite {
+        CompactCallsite::MidTurnContinuation | CompactCallsite::PreSamplingModelSwitch => {
+            // Mid-turn and pre-sampling model-switch compaction continue the in-flight turn and
+            // therefore must keep canonical context anchored above the latest real user turn.
+            let initial_context = sess.build_initial_context(turn_context.as_ref()).await;
+            insert_initial_context_before_last_real_user(&mut new_history, initial_context);
+        }
+        CompactCallsite::ManualCompact => {
+            // Manual `/compact` intentionally rewrites transcript history without reseeding turn
+            // context here; the task marks initial context unseeded for the next user turn.
+        }
+        CompactCallsite::PreTurnIncludingIncomingUserMessage
+        | CompactCallsite::PreTurnExcludingIncomingUserMessage => {
+            // Pre-turn compaction persists canonical context directly above the incoming user
+            // message in `run_turn`, not inside compacted replacement history.
+        }
     }
     // Reattach stripped model-switch updates into replacement history so post-compaction
     // sampling keeps model-switch guidance regardless of compaction callsite.

codex-rs/core/src/compact_remote.rs

@@ -3,7 +3,7 @@ use std::sync::Arc;
 use crate::Prompt;
 use crate::codex::Session;
 use crate::codex::TurnContext;
-use crate::compact::AutoCompactCallsite;
+use crate::compact::CompactCallsite;
 use crate::compact::extract_latest_model_switch_update_from_items;
 use crate::compact::extract_trailing_model_switch_update_for_compaction_request;
 use crate::compact::insert_initial_context_before_last_real_user;
@@ -32,7 +32,7 @@ use tracing::info;
 pub(crate) async fn run_inline_remote_auto_compact_task(
     sess: Arc<Session>,
     turn_context: Arc<TurnContext>,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     run_remote_compact_task_inner(&sess, &turn_context, auto_compact_callsite, incoming_items)
@@ -51,19 +51,13 @@ pub(crate) async fn run_remote_compact_task(
     });
     sess.send_event(&turn_context, start_event).await;
 
-    run_remote_compact_task_inner(
-        &sess,
-        &turn_context,
-        AutoCompactCallsite::PreTurnExcludingIncomingUserMessage,
-        None,
-    )
-    .await
+    run_remote_compact_task_inner(&sess, &turn_context, CompactCallsite::ManualCompact, None).await
 }
 
 async fn run_remote_compact_task_inner(
     sess: &Arc<Session>,
     turn_context: &Arc<TurnContext>,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     if let Err(err) = run_remote_compact_task_inner_impl(
@@ -88,7 +82,7 @@ async fn run_remote_compact_task_inner(
 async fn run_remote_compact_task_inner_impl(
     sess: &Arc<Session>,
     turn_context: &Arc<TurnContext>,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     incoming_items: Option<Vec<ResponseItem>>,
 ) -> CodexResult<()> {
     let compaction_item = TurnItem::ContextCompaction(ContextCompactionItem::new());
@@ -168,12 +162,22 @@ async fn run_remote_compact_task_inner_impl(
         })
         .await?;
     new_history = process_compacted_history(new_history);
-    if matches!(
-        auto_compact_callsite,
-        AutoCompactCallsite::MidTurnContinuation | AutoCompactCallsite::PreSamplingModelSwitch
-    ) {
-        let initial_context = sess.build_initial_context(turn_context.as_ref()).await;
-        insert_initial_context_before_last_real_user(&mut new_history, initial_context);
+    match auto_compact_callsite {
+        CompactCallsite::MidTurnContinuation | CompactCallsite::PreSamplingModelSwitch => {
+            // Mid-turn and pre-sampling model-switch compaction continue the in-flight turn and
+            // therefore must keep canonical context anchored above the latest real user turn.
+            let initial_context = sess.build_initial_context(turn_context.as_ref()).await;
+            insert_initial_context_before_last_real_user(&mut new_history, initial_context);
+        }
+        CompactCallsite::ManualCompact => {
+            // Manual `/compact` intentionally rewrites transcript history without reseeding turn
+            // context here; the task marks initial context unseeded for the next user turn.
+        }
+        CompactCallsite::PreTurnIncludingIncomingUserMessage
+        | CompactCallsite::PreTurnExcludingIncomingUserMessage => {
+            // Pre-turn compaction persists canonical context directly above the incoming user
+            // message in `run_turn`, not inside compacted replacement history.
+        }
     }
     if let Some(incoming_items) = incoming_items.as_ref() {
         let incoming_history_items: Vec<ResponseItem> = incoming_items
@@ -271,7 +275,7 @@ fn remove_incoming_echoes_from_compacted_history(
 
 fn log_remote_compact_failure(
     turn_context: &TurnContext,
-    auto_compact_callsite: AutoCompactCallsite,
+    auto_compact_callsite: CompactCallsite,
     log_data: &CompactRequestLogData,
     total_usage_breakdown: TotalTokenUsageBreakdown,
     err: &CodexErr,