From 4de1765a83138aeed54518060d1fd61d17a42f85 Mon Sep 17 00:00:00 2001
From: Sisyphus <sisyphus@local>
Date: Sat, 22 Aug 2026 21:17:42 +0800
Subject: [PATCH] fix(loop): run applyCompression over the unpruned view
 (billion-context-pi#195)
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The streaming loop ctx passed processedMessages (pruned view with
acp_summary_* stripped) to applyCompression, so active blocks whose raws
were pruned had no resolvable anchor — bN promotion failed with the
self-contradictory 'already compressed' error. Add a dedicated
compressMessages field (unpruned originalMessages) used only by
applyCompression; wire rebuilds keep using the pruned view.
---
 src/loop/core.ts | 2 ++
 src/server.ts    | 2 +-
 src/stream.ts    | 6 +++++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/loop/core.ts b/src/loop/core.ts
index a8e873b..4f50098 100644
--- a/src/loop/core.ts
+++ b/src/loop/core.ts
@@ -28,6 +28,8 @@ export interface LoopCtx {
     core: CompressionCore;
     config: Config;
     messages: CoreMessage[];
+    /** View handed to applyCompression (see RewriteCtx.compressMessages). */
+    compressMessages?: CoreMessage[];
     session: Session;
     log: (msg: string) => void;
     proxyUrl?: string;
diff --git a/src/server.ts b/src/server.ts
index b40842e..00065c1 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -1649,7 +1649,7 @@ async function forward(
             const adapter = pickAdapter(prepared.protocol, parsedReq, textProtocol, prepared.responsesProjection, prepared.anthropicSystem);
             const loop = runCompressLoop(
                 streamToRead,
-                { core, config, messages: prepared.processedMessages.length > 0 ? prepared.processedMessages : prepared.originalMessages, session: prepared.session, log: ctx.log, proxyUrl, protocol: prepared.protocol, textProtocol, debug: opts.debug, nudge: prepared.nudge },
+                { core, config, messages: prepared.processedMessages.length > 0 ? prepared.processedMessages : prepared.originalMessages, compressMessages: prepared.originalMessages, session: prepared.session, log: ctx.log, proxyUrl, protocol: prepared.protocol, textProtocol, debug: opts.debug, nudge: prepared.nudge },
                 parsedReq,
                 { url: upstreamUrl, headers: reqHeaders },
                 adapter,
diff --git a/src/stream.ts b/src/stream.ts
index 770722c..3b40aa8 100644
--- a/src/stream.ts
+++ b/src/stream.ts
@@ -8,6 +8,10 @@ export type RewriteCtx = {
     core: CompressionCore;
     config: Config;
     messages: CoreMessage[];
+    /** View handed to applyCompression. Defaults to `messages`; hosts whose
+     *  `messages` view has pruned/hidden content (so block anchors can't
+     *  resolve) pass the unpruned log here (billion-context-pi#195). */
+    compressMessages?: CoreMessage[];
     session: Session;
     log: (msg: string) => void;
     debug?: boolean;
@@ -227,7 +231,7 @@ export function applyRanges(ranges: ReturnType<typeof parseCompressInput>, ctx:
     try {
         const res = ctx.core.applyCompression({
             ranges,
-            messages: ctx.messages,
+            messages: ctx.compressMessages ?? ctx.messages,
             state: ctx.session.state,
             config: ctx.config,
         });