diff --git a/src/QueryEngine.ts b/src/QueryEngine.ts
index c9697c768..8e48ed757 100644
--- a/src/QueryEngine.ts
+++ b/src/QueryEngine.ts
@@ -248,6 +248,7 @@ export class QueryEngine {
     } = this.config
 
     this.discoveredSkillNames.clear()
+    this.permissionDenials = []
     setCwd(cwd)
     const persistSession = !isSessionPersistenceDisabled()
     const startTime = Date.now()
diff --git a/src/cli/transports/SSETransport.ts b/src/cli/transports/SSETransport.ts
index 42b90afbd..110f71957 100644
--- a/src/cli/transports/SSETransport.ts
+++ b/src/cli/transports/SSETransport.ts
@@ -350,6 +350,7 @@ export class SSETransport implements Transport {
     const reader = body.getReader()
     const decoder = new TextDecoder()
     let buffer = ''
+    const MAX_BUFFER_BYTES = 1024 * 1024 // 1MB — SSE frames include event/data/id prefixes
 
     try {
       while (true) {
@@ -357,6 +358,14 @@ export class SSETransport implements Transport {
         if (done) break
 
         buffer += decoder.decode(value, STREAM_DECODE_OPTS)
+        if (buffer.length > MAX_BUFFER_BYTES) {
+          logForDebugging(
+            `SSETransport: Buffer exceeded ${MAX_BUFFER_BYTES} bytes — dropping connection`,
+            { level: 'error' },
+          )
+          logForDiagnosticsNoPII('error', 'cli_sse_buffer_overflow')
+          break
+        }
         const { frames, remaining } = parseSSEFrames(buffer)
         buffer = remaining
 
diff --git a/src/screens/REPL.tsx b/src/screens/REPL.tsx
index fe26e38cf..0cd46d38c 100644
--- a/src/screens/REPL.tsx
+++ b/src/screens/REPL.tsx
@@ -305,8 +305,9 @@ import {
 import { deserializeMessages } from '../utils/conversationRecovery.js';
 import { extractReadFilesFromMessages, extractBashToolsFromMessages } from '../utils/queryHelpers.js';
 import { resetMicrocompactState } from '../services/compact/microCompact.js';
-import { runPostCompactCleanup } from '../services/compact/postCompactCleanup.js';
+import { runPostCompactCleanup, registerCompactCleanup } from '../services/compact/postCompactCleanup.js';
 import {
+  createContentReplacementState,
   provisionContentReplacementState,
   reconstructContentReplacementState,
   type ContentReplacementRecord,
@@ -1778,6 +1779,9 @@ export function REPL({
   const [contentReplacementStateRef] = useState(() => ({
     current: provisionContentReplacementState(initialMessages, initialContentReplacements),
   }));
+  registerCompactCleanup(() => {
+    contentReplacementStateRef.current = createContentReplacementState();
+  });
 
   const [haveShownCostDialog, setHaveShownCostDialog] = useState(getGlobalConfig().hasAcknowledgedCostThreshold);
   const [vimMode, setVimMode] = useState<VimMode>('INSERT');
diff --git a/src/services/compact/postCompactCleanup.ts b/src/services/compact/postCompactCleanup.ts
index b89e3a0be..b52730217 100644
--- a/src/services/compact/postCompactCleanup.ts
+++ b/src/services/compact/postCompactCleanup.ts
@@ -10,6 +10,17 @@ import { clearSessionMessagesCache } from '../../utils/sessionStorage.js'
 import { clearBetaTracingState } from '../../utils/telemetry/betaSessionTracing.js'
 import { resetMicrocompactState } from './microCompact.js'
 
+/**
+ * Compact-scoped cleanup callbacks registered by REPL or other long-lived
+ * components. Called during runPostCompactCleanup() so instance-scoped state
+ * (e.g. contentReplacementState) is freed alongside module-level caches.
+ */
+const compactCleanupCallbacks: Array<() => void> = []
+
+export function registerCompactCleanup(callback: () => void): void {
+  compactCleanupCallbacks.push(callback)
+}
+
 /**
  * Run cleanup of caches and tracking state after compaction.
  * Call this after both auto-compact and manual /compact to free memory
@@ -88,4 +99,11 @@ export function runPostCompactCleanup(querySource?: QuerySource): void {
       })
   }
   clearSessionMessagesCache()
+  for (const cb of compactCleanupCallbacks) {
+    try {
+      cb()
+    } catch (error) {
+      logError(error)
+    }
+  }
 }
diff --git a/src/utils/log.ts b/src/utils/log.ts
index 7d15b2fb3..7b85e4cf7 100644
--- a/src/utils/log.ts
+++ b/src/utils/log.ts
@@ -17,7 +17,7 @@ import {
 import { CACHE_PATHS } from './cachePaths.js'
 import { stripDisplayTags, stripDisplayTagsAllowEmpty } from './displayTags.js'
 import { isEnvTruthy } from './envUtils.js'
-import { toError } from './errors.js'
+import { toError, shortErrorStack } from './errors.js'
 import { isEssentialTrafficOnly } from './privacyLevel.js'
 import { jsonParse } from './slowOperations.js'
 
@@ -175,7 +175,7 @@ export function logError(error: unknown): void {
       return
     }
 
-    const errorStr = err.stack || err.message
+    const errorStr = shortErrorStack(err)
 
     const errorInfo = {
       error: errorStr,