diff --git a/package-lock.json b/package-lock.json
index b98a8c8..672b2d3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -15,7 +15,7 @@
       "devDependencies": {
         "@types/node": "^22.0.0",
         "@types/node-forge": "^1.3.14",
-        "acp-kernel": "0.0.34",
+        "acp-kernel": "0.0.36",
         "fzstd": "0.1.1",
         "node-forge": "^1.4.0",
         "tar": "^7.5.22",
@@ -972,9 +972,9 @@
       }
     },
     "node_modules/acp-kernel": {
-      "version": "0.0.34",
-      "resolved": "https://registry.npmjs.org/acp-kernel/-/acp-kernel-0.0.34.tgz",
-      "integrity": "sha512-iB1B7A92xYESmtBNJlUUP27A9t7yP/ULkC+rgnHDrwvC/rGJBMgkm0/P2tnXPRadwUNfXUoL3CGGzg7EkTUF8A==",
+      "version": "0.0.36",
+      "resolved": "https://registry.npmjs.org/acp-kernel/-/acp-kernel-0.0.36.tgz",
+      "integrity": "sha512-w3lyfah74H35HHBzmw/jwLVixPRfC1K7wbFjKrwoV1qdw5847kjzNxiJ3i6upEY3YPJI517A5FyPhne0vbvSVg==",
       "dev": true,
       "license": "MIT",
       "engines": {
diff --git a/package.json b/package.json
index 938e6d1..4c6a6c4 100644
--- a/package.json
+++ b/package.json
@@ -41,7 +41,7 @@
   "devDependencies": {
     "@types/node": "^22.0.0",
     "@types/node-forge": "^1.3.14",
-    "acp-kernel": "0.0.34",
+    "acp-kernel": "0.0.36",
     "fzstd": "0.1.1",
     "node-forge": "^1.4.0",
     "tar": "^7.5.22",
diff --git a/src/server.ts b/src/server.ts
index 4afb6af..b40842e 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -1,6 +1,6 @@
 import http from "node:http";
 import fs from "node:fs";
-import { createCore, type CompressionCore, type Config, type CoreMessage, type NudgeDecision, type Prompts, defaultPrompts, estimateTokensFast, renderNudgeText, deactivateBlock } from "acp-kernel";
+import { createCore, type CompressionCore, type Config, type CoreMessage, type NudgeDecision, type Prompts, defaultPrompts, estimateTokensFast, renderNudgeText, deactivateBlock, viableRanges } from "acp-kernel";
 import { resolveCompress, resolveCompressPrompts, resolveRequestConfig } from "./compress-settings.js";
 import type { ProxyOptions } from "./config.js";
 import { loadOptions, loadRoutes } from "./config.js";
@@ -870,6 +870,10 @@ function prepareAnthropic(
         const tokenCount = session.stats.lastInputTokens;
         const turn = core.processTurn({ messages: msgs, state: session.state, config, tokenCount, renderTags: "text-only" });
         session.state = turn.state;
+        // Drop sub-viability fragments before any consumer sees them: a tiny
+        // range in the list makes batched compress attempts fail atomically
+        // (kernel validates the whole batch). Mirrors billion-context-pi.
+        if (turn.nudge) turn.nudge.compressibleRanges = viableRanges(turn.nudge.compressibleRanges);
         nudge = turn.nudge;
         session.stats.contextTokens = tokenCount;
         if (!session.meta.title) {
@@ -948,6 +952,10 @@ function prepareOpenai(
         const tokenCount = session.stats.lastInputTokens;
         const turn = core.processTurn({ messages: msgs, state: session.state, config, tokenCount, renderTags: "text-only" });
         session.state = turn.state;
+        // Drop sub-viability fragments before any consumer sees them: a tiny
+        // range in the list makes batched compress attempts fail atomically
+        // (kernel validates the whole batch). Mirrors billion-context-pi.
+        if (turn.nudge) turn.nudge.compressibleRanges = viableRanges(turn.nudge.compressibleRanges);
         nudge = turn.nudge;
         session.stats.contextTokens = tokenCount;
         if (!session.meta.title) {
@@ -1044,6 +1052,10 @@ function prepareResponses(
         const tokenCount = session.stats.lastInputTokens;
         const turn = core.processTurn({ messages: msgs, state: session.state, config, tokenCount, renderTags: process.env.ACP_RENDER_NONE ? "none" : "text-only" });
         session.state = turn.state;
+        // Drop sub-viability fragments before any consumer sees them: a tiny
+        // range in the list makes batched compress attempts fail atomically
+        // (kernel validates the whole batch). Mirrors billion-context-pi.
+        if (turn.nudge) turn.nudge.compressibleRanges = viableRanges(turn.nudge.compressibleRanges);
         nudge = turn.nudge;
         session.stats.contextTokens = tokenCount;
         if (!session.meta.title) {