From 9f1deefa7128889fd8a947964f04262bfa724b84 Mon Sep 17 00:00:00 2001
From: firecoperana <18252262+firecoperana@users.noreply.github.com>
Date: Sat, 2 May 2026 08:09:28 -0500
Subject: [PATCH] server: revert checkpoint fix (#1716)

Co-authored-by: firecoperana <firecoperana>
---
 examples/server/server-context.cpp | 46 +++++++++---------------------
 1 file changed, 13 insertions(+), 33 deletions(-)

diff --git a/examples/server/server-context.cpp b/examples/server/server-context.cpp
index b38d13a02..c747786ea 100644
--- a/examples/server/server-context.cpp
+++ b/examples/server/server-context.cpp
@@ -3215,22 +3215,19 @@ void  server_context::create_checkpoint_at_interval(server_slot & slot, const gp
         if (slot.checkpoint_pos + params_base.ctx_checkpoints_interval <= 1 + pos) {
             bool created = create_checkpoint(slot);
             if (created) {
-            slot.checkpoint_pos = pos;
+                slot.checkpoint_pos = pos;
+            }
         }
     }
 }
-}
 
 void server_context::apply_checkpoint(server_slot & slot) {
     llama_pos pos_next = slot.cache_tokens.pos_next(slot.n_past);
-    const bool has_recurrent = llama_model_has_recurrent(llama_get_model(slot.ctx));
-    // For hybrid/recurrent models, pos_min semantics don't apply: the recurrent state is a single
-    // snapshot, not a per-token window. Use pos_max against n_past to match whole-prefix checkpoints.
     const auto pos_min_thold = std::max(0, pos_next - 1);
     if (slot.n_past > 0 && slot.n_past < slot.cache_tokens.n_tokens()) {
         int32_t pos_min = llama_kv_cache_seq_pos_min(slot.ctx, slot.id);
 
-        if (has_recurrent || pos_min > pos_min_thold) {
+        if (pos_min > pos_min_thold) {
             SLT_WRN(slot, "n_past = %d, slot.prompt.tokens.size() = %d, seq_id = %d, pos_min = %d\n", slot.n_past, (int)slot.cache_tokens.size(), slot.id, pos_min);
 
             // search for a context checkpoint
@@ -3238,13 +3235,7 @@ void server_context::apply_checkpoint(server_slot & slot) {
                 slot.server_cached_prompt.checkpoints.rbegin(),
                 slot.server_cached_prompt.checkpoints.rend(),
                 [&](const auto & cur) {
-                    // guarantee that a checkpoint will result in at least one token being processed [TAG_PROMPT_LOGITS]
-                    if (has_recurrent) {
-                        // recurrent/hybrid: only whole-prefix checkpoints are valid; pick the latest one
-                        // that covers no more than the current n_past and still leaves tokens to decode.
-                        return cur.pos_max <= slot.n_past && cur.pos_max < pos_next;
-                    }
-                    return cur.pos_min < pos_min_thold;
+                    return cur.pos_min < pos_min_thold || cur.pos_min == 0;
                 }
             );
 
@@ -3270,33 +3261,22 @@ void server_context::apply_checkpoint(server_slot & slot) {
             }
 
             if (do_reset) {
-                if (has_recurrent) {
-                    // Without a usable recurrent checkpoint, preserving prefix state leaks stale recurrent memory
-                    // from prior requests into the current prompt. Force a full prompt re-processing fallback.
-                    SLT_WRN(slot, "%s", "no usable hybrid/recurrent checkpoint; forcing full prompt re-processing\n");
-                    slot.n_past = 0;
-                    slot.n_past_prompt = 0;
-                    slot.n_past_se = 0;
-                    slot.ga_i = 0;
-                    common_sampler_reset(slot.ctx_sampling);
-                } else {
-                    SLT_WRN(slot, "forcing full prompt re-processing due to lack of cache data (likely due to SWA, see %s)\n",
-                        "https://github.com/ggml-org/llama.cpp/pull/13194#issuecomment-2868343055");
-                    slot.n_past = 0;
-                    slot.n_past_prompt = 0;
-                }
+                SLT_WRN(slot, "forcing full prompt re-processing due to lack of cache data (likely due to SWA, see %s)\n",
+                    "https://github.com/ggml-org/llama.cpp/pull/13194#issuecomment-2868343055");
+                slot.n_past = 0;
+                slot.n_past_prompt = 0;
+                slot.n_past_se = 0;
+                slot.ga_i = 0;
+                common_sampler_reset(slot.ctx_sampling);
             }
         }
     }
 
     {
-        // erase checkpoints that are no longer consistent with the current decode position.
-        // Transformer: anything with pos_min beyond the threshold is stale.
-        // Recurrent/hybrid: anything with pos_max past pos_next refers to future tokens we've rewound past.
+        // erase any checkpoints with pos_min > pos_min_thold
         for (auto it = slot.server_cached_prompt.checkpoints.begin(); it != slot.server_cached_prompt.checkpoints.end();) {
             const auto & cur = *it;
-            const bool stale = has_recurrent ? (cur.pos_max > pos_next) : (cur.pos_min > pos_min_thold);
-            if (stale) {
+            if (cur.pos_min > pos_min_thold) {
                 SLT_WRN(slot, "erased invalidated context checkpoint (pos_min = %d, pos_max = %d, size = %.3f MiB)\n", cur.pos_min, cur.pos_max, (float)cur.data.size() / 1024 / 1024);
                 it = slot.server_cached_prompt.checkpoints.erase(it);
             } else {