feat(hooks): capture reasoning and assistant messages in hooks (#719)

src/cli/App.tsx

@@ -2669,6 +2669,17 @@ export default function App({
             lastDequeuedMessageRef.current = null; // Clear - message was processed successfully
             lastSentInputRef.current = null; // Clear - no recovery needed
 
+            // Get last assistant message and reasoning for Stop hook
+            const lastAssistant = Array.from(
+              buffersRef.current.byId.values(),
+            ).findLast((item) => item.kind === "assistant" && "text" in item);
+            const assistantMessage =
+              lastAssistant && "text" in lastAssistant
+                ? lastAssistant.text
+                : undefined;
+            const precedingReasoning = buffersRef.current.lastReasoning;
+            buffersRef.current.lastReasoning = undefined; // Clear after use
+
             // Run Stop hooks - if blocked/errored, continue the conversation with feedback
             const stopHookResult = await runStopHooks(
               stopReasonToHandle,
@@ -2676,6 +2687,9 @@ export default function App({
               Array.from(buffersRef.current.byId.values()).filter(
                 (item) => item.kind === "tool_call",
               ).length,
+              undefined, // workingDirectory (uses default)
+              precedingReasoning,
+              assistantMessage,
             );
 
             // If hook blocked (exit 2), inject stderr feedback and continue conversation

src/cli/helpers/accumulator.ts

@@ -181,6 +181,8 @@ export type Buffers = {
   interrupted?: boolean; // Track if stream was interrupted by user (skip stale refreshes)
   commitGeneration?: number; // Incremented when resuming from error to invalidate pending refreshes
   abortGeneration?: number; // Incremented on each interrupt to detect cancellation across async boundaries
+  lastReasoning?: string; // Track last reasoning content for hooks (PostToolUse, Stop)
+  lastAssistantMessage?: string; // Track last assistant message for hooks (PostToolUse)
   usage: {
     promptTokens: number;
     completionTokens: number;
@@ -243,6 +245,15 @@ function markAsFinished(b: Buffers, id: string) {
     const updatedLine = { ...line, phase: "finished" as const };
     b.byId.set(id, updatedLine);
     // console.log(`[MARK_FINISHED] Successfully marked ${id} as finished`);
+
+    // Track last reasoning content for hooks (PostToolUse and Stop will include it)
+    if (line.kind === "reasoning" && "text" in line && line.text) {
+      b.lastReasoning = line.text;
+    }
+    // Track last assistant message for hooks (PostToolUse will include it)
+    if (line.kind === "assistant" && "text" in line && line.text) {
+      b.lastAssistantMessage = line.text;
+    }
   } else {
     // console.log(`[MARK_FINISHED] Did NOT mark ${id} as finished (conditions not met)`);
   }
@@ -717,6 +728,12 @@ export function onChunk(b: Buffers, chunk: LettaStreamingResponse) {
               // Args parsing failed
             }
 
+            // Get and clear preceding reasoning/message for hook
+            const precedingReasoning = b.lastReasoning;
+            const precedingAssistantMessage = b.lastAssistantMessage;
+            b.lastReasoning = undefined;
+            b.lastAssistantMessage = undefined;
+
             runPostToolUseHooks(
               serverToolInfo.toolName,
               parsedArgs,
@@ -727,6 +744,8 @@ export function onChunk(b: Buffers, chunk: LettaStreamingResponse) {
               toolCallId,
               undefined,
               b.agentId,
+              precedingReasoning,
+              precedingAssistantMessage,
             ).catch(() => {});
 
             b.serverToolCalls.delete(toolCallId);