fix(session): harden usage accounting and memory flush recovery

src/auto-reply/reply/agent-runner-memory.ts

@@ -96,6 +96,57 @@ function parseUsageFromTranscriptLine(line: string): ReturnType<typeof normalize
   return undefined;
 }
 
+function resolveSessionLogPath(
+  sessionId?: string,
+  sessionEntry?: SessionEntry,
+  sessionKey?: string,
+  opts?: { storePath?: string },
+): string | undefined {
+  if (!sessionId) {
+    return undefined;
+  }
+
+  try {
+    const transcriptPath = (
+      sessionEntry as (SessionEntry & { transcriptPath?: string }) | undefined
+    )?.transcriptPath?.trim();
+    const sessionFile = sessionEntry?.sessionFile?.trim() || transcriptPath;
+    const agentId = resolveAgentIdFromSessionKey(sessionKey);
+    const pathOpts = resolveSessionFilePathOptions({
+      agentId,
+      storePath: opts?.storePath,
+    });
+    // Normalize sessionFile through resolveSessionFilePath so relative entries
+    // are resolved against the sessions dir/store layout, not process.cwd().
+    return resolveSessionFilePath(
+      sessionId,
+      sessionFile ? { sessionFile } : sessionEntry,
+      pathOpts,
+    );
+  } catch {
+    return undefined;
+  }
+}
+
+async function readSessionLogByteSize(
+  sessionId?: string,
+  sessionEntry?: SessionEntry,
+  sessionKey?: string,
+  opts?: { storePath?: string },
+): Promise<number | undefined> {
+  const logPath = resolveSessionLogPath(sessionId, sessionEntry, sessionKey, opts);
+  if (!logPath) {
+    return undefined;
+  }
+  try {
+    const stat = await fs.promises.stat(logPath);
+    const size = Math.floor(stat.size);
+    return Number.isFinite(size) && size >= 0 ? size : undefined;
+  } catch {
+    return undefined;
+  }
+}
+
 async function readLastNonzeroUsageFromSessionLog(logPath: string) {
   const handle = await fs.promises.open(logPath, "r");
   try {
@@ -134,28 +185,12 @@ export async function readPromptTokensFromSessionLog(
   sessionKey?: string,
   opts?: { storePath?: string },
 ): Promise<SessionTranscriptUsageSnapshot | undefined> {
-  if (!sessionId) {
+  const logPath = resolveSessionLogPath(sessionId, sessionEntry, sessionKey, opts);
+  if (!logPath) {
     return undefined;
   }
 
   try {
-    const transcriptPath = (
-      sessionEntry as (SessionEntry & { transcriptPath?: string }) | undefined
-    )?.transcriptPath?.trim();
-    const sessionFile = sessionEntry?.sessionFile?.trim() || transcriptPath;
-    const agentId = resolveAgentIdFromSessionKey(sessionKey);
-    const pathOpts = resolveSessionFilePathOptions({
-      agentId,
-      storePath: opts?.storePath,
-    });
-    // Normalize sessionFile through resolveSessionFilePath so relative entries
-    // are resolved against the sessions dir/store layout, not process.cwd().
-    const logPath = resolveSessionFilePath(
-      sessionId,
-      sessionFile ? { sessionFile } : sessionEntry,
-      pathOpts,
-    );
-
     const lastUsage = await readLastNonzeroUsageFromSessionLog(logPath);
     if (!lastUsage) {
       return undefined;
@@ -262,6 +297,23 @@ export async function runMemoryFlushIfNeeded(params: {
   const shouldReadTranscript =
     canAttemptFlush && entry && (!hasFreshPersistedPromptTokens || shouldReadTranscriptForOutput);
 
+  const forceFlushTranscriptBytes = memoryFlushSettings.forceFlushTranscriptBytes;
+  const shouldCheckTranscriptSizeForForcedFlush =
+    canAttemptFlush &&
+    entry &&
+    Number.isFinite(forceFlushTranscriptBytes) &&
+    forceFlushTranscriptBytes > 0;
+  const transcriptByteSize = shouldCheckTranscriptSizeForForcedFlush
+    ? await readSessionLogByteSize(
+        params.followupRun.run.sessionId,
+        entry,
+        params.sessionKey ?? params.followupRun.run.sessionKey,
+        { storePath: params.storePath },
+      )
+    : undefined;
+  const shouldForceFlushByTranscriptSize =
+    typeof transcriptByteSize === "number" && transcriptByteSize >= forceFlushTranscriptBytes;
+
   const transcriptUsageSnapshot = shouldReadTranscript
     ? await readPromptTokensFromSessionLog(
         params.followupRun.run.sessionId,
@@ -341,21 +393,23 @@ export async function runMemoryFlushIfNeeded(params: {
       `compactionCount=${entry?.compactionCount ?? 0} memoryFlushCompactionCount=${entry?.memoryFlushCompactionCount ?? "undefined"} ` +
       `persistedPromptTokens=${persistedPromptTokens ?? "undefined"} persistedFresh=${entry?.totalTokensFresh === true} ` +
       `promptTokensEst=${promptTokenEstimate ?? "undefined"} transcriptPromptTokens=${transcriptPromptTokens ?? "undefined"} transcriptOutputTokens=${transcriptOutputTokens ?? "undefined"} ` +
-      `projectedTokenCount=${projectedTokenCount ?? "undefined"}`,
+      `projectedTokenCount=${projectedTokenCount ?? "undefined"} transcriptBytes=${transcriptByteSize ?? "undefined"} ` +
+      `forceFlushTranscriptBytes=${forceFlushTranscriptBytes} forceFlushByTranscriptSize=${shouldForceFlushByTranscriptSize}`,
   );
 
   const shouldFlushMemory =
-    memoryFlushSettings &&
-    memoryFlushWritable &&
-    !params.isHeartbeat &&
-    !isCli &&
-    shouldRunMemoryFlush({
-      entry,
-      tokenCount: tokenCountForFlush,
-      contextWindowTokens,
-      reserveTokensFloor: memoryFlushSettings.reserveTokensFloor,
-      softThresholdTokens: memoryFlushSettings.softThresholdTokens,
-    });
+    (memoryFlushSettings &&
+      memoryFlushWritable &&
+      !params.isHeartbeat &&
+      !isCli &&
+      shouldRunMemoryFlush({
+        entry,
+        tokenCount: tokenCountForFlush,
+        contextWindowTokens,
+        reserveTokensFloor: memoryFlushSettings.reserveTokensFloor,
+        softThresholdTokens: memoryFlushSettings.softThresholdTokens,
+      })) ||
+    shouldForceFlushByTranscriptSize;
 
   if (!shouldFlushMemory) {
     return entry ?? params.sessionEntry;