Avoid duplicate Claude result text (#1095)

packages/server/src/server/agent/providers/claude/agent.test.ts

@@ -1461,4 +1461,64 @@ describe("ClaudeAgentSession context window usage", () => {
     expect(timelineEvents).toEqual([]);
     expect(events.some((event) => event.type === "turn_completed")).toBe(true);
   });
+
+  test("result.result is not duplicated when assistant text already streamed with zero token usage", async () => {
+    const queryFactory = createQueryFactoryForTurns([
+      [
+        {
+          type: "system",
+          subtype: "init",
+          session_id: "session-third-party",
+          permissionMode: "default",
+        },
+        {
+          type: "assistant",
+          message: {
+            id: "assistant-third-party-1",
+            role: "assistant",
+            content: [{ type: "text", text: "Here is the answer." }],
+            usage: {
+              input_tokens: 0,
+              output_tokens: 0,
+            },
+          },
+          session_id: "session-third-party",
+          uuid: "assistant-third-party-event-1",
+        },
+        {
+          type: "result",
+          subtype: "success",
+          result: "Here is the answer.",
+          is_error: false,
+          duration_ms: 100,
+          duration_api_ms: 80,
+          num_turns: 1,
+          stop_reason: null,
+          total_cost_usd: 0.01,
+          usage: {
+            input_tokens: 10,
+            cache_read_input_tokens: 0,
+            output_tokens: 0,
+          },
+          permission_denials: [],
+          uuid: "result-third-party-1",
+          session_id: "session-third-party",
+        },
+      ],
+    ]);
+    const client = new ClaudeAgentClient({
+      logger,
+      queryFactory,
+      resolveBinary: async () => "/test/claude/bin",
+    });
+    const session = await client.createSession({
+      provider: "claude",
+      cwd: process.cwd(),
+    });
+
+    const result = await session.run("turn");
+    await session.close();
+
+    expect(result.timeline).toEqual([{ type: "assistant_message", text: "Here is the answer." }]);
+  });
 });

packages/server/src/server/agent/providers/claude/agent.ts

@@ -1568,6 +1568,7 @@ class ClaudeAgentSession implements AgentSession {
   private pendingInterruptAbort = false;
   private lastForegroundPromptText: string | null = null;
   private foregroundHasVisibleActivity = false;
+  private activeTurnHasAssistantText = false;
   private lastContextWindowUsedTokens: number | undefined;
   private lastContextWindowMaxTokens: number | undefined;
   private lastStreamRequestInputTokens: number | undefined;
@@ -1692,6 +1693,7 @@ class ClaudeAgentSession implements AgentSession {
     const turnId = this.createTurnId("foreground");
     this.activeForegroundTurnId = turnId;
     this.foregroundHasVisibleActivity = false;
+    this.activeTurnHasAssistantText = false;
     this.transitionTurnState("foreground", "foreground turn started");
     this.clearRecentStderr();
 
@@ -2630,6 +2632,7 @@ class ClaudeAgentSession implements AgentSession {
     this.activeForegroundTurnId = null;
     this.lastForegroundPromptText = null;
     this.cancelCurrentTurn = null;
+    this.activeTurnHasAssistantText = false;
     this.syncTurnState("foreground turn terminal");
   }
 
@@ -2645,9 +2648,11 @@ class ClaudeAgentSession implements AgentSession {
         this.activeForegroundTurnId = null;
         this.lastForegroundPromptText = null;
         this.cancelCurrentTurn = null;
+        this.activeTurnHasAssistantText = false;
         this.syncTurnState("foreground turn terminal");
       } else if (this.autonomousTurn) {
         this.autonomousTurn = null;
+        this.activeTurnHasAssistantText = false;
         this.syncTurnState("autonomous turn terminal");
       }
     }
@@ -2660,6 +2665,7 @@ class ClaudeAgentSession implements AgentSession {
     this.autonomousTurn = {
       id: this.createTurnId("autonomous"),
     };
+    this.activeTurnHasAssistantText = false;
     this.notifySubscribers({ type: "turn_started", provider: "claude" });
     this.syncTurnState("autonomous turn started");
   }
@@ -2670,6 +2676,7 @@ class ClaudeAgentSession implements AgentSession {
     }
     this.notifySubscribers({ type: "turn_completed", provider: "claude" });
     this.autonomousTurn = null;
+    this.activeTurnHasAssistantText = false;
     this.syncTurnState("autonomous turn completed");
   }
 
@@ -2898,7 +2905,6 @@ class ClaudeAgentSession implements AgentSession {
     if (events.length === 0) {
       return;
     }
-
     if (
       this.pendingInterruptAbort &&
       message.type === "result" &&
@@ -2909,6 +2915,11 @@ class ClaudeAgentSession implements AgentSession {
       this.logger.debug("Suppressing stale Claude interrupt terminal result");
       return;
     }
+    if (
+      events.some((event) => event.type === "timeline" && event.item.type === "assistant_message")
+    ) {
+      this.activeTurnHasAssistantText = true;
+    }
     if (
       this.activeForegroundTurnId &&
       events.some(
@@ -3231,12 +3242,12 @@ class ClaudeAgentSession implements AgentSession {
     if (message.subtype === "success") {
       // Built-in slash commands (e.g. /voice, /usage, "Unknown command: …")
       // run client-side in the Claude CLI with no model turn — output_tokens
-      // is 0 and the user-visible text is carried in `result`. Surface it as
-      // an assistant message so the turn doesn't end silently. Normal turns
-      // have output_tokens > 0 and their text is already in the stream.
+      // is 0 and the user-visible text is carried in `result`. Surface it only
+      // when the turn has not already emitted assistant text so zero-token
+      // accounting from provider gateways does not duplicate streamed output.
       const resultText = typeof message.result === "string" ? message.result.trim() : "";
       const outputTokens = message.usage?.output_tokens;
-      if (resultText.length > 0 && outputTokens === 0) {
+      if (resultText.length > 0 && outputTokens === 0 && !this.activeTurnHasAssistantText) {
         events.push({
           type: "timeline",
           provider: "claude",