fix: properly track isProcessing state to block duplicate message submission

The isProcessing field existed on conversations but was never set to true
in production code, making all submission guards effectively no-ops.

- Add setProcessingForConversation to conversations store and claude.ts
- Set isProcessing=true after send_prompt succeeds in handleSubmit and handleQuickAction
- Set isProcessing=false when claude:state emits idle, success, or error
- Add tests for the new setProcessingForConversation logic

src/lib/components/InputBar.svelte

@@ -339,6 +339,7 @@ User: ${formattedMessage}`;
         conversationId,
         message: messageToSend,
       });
+      claudeStore.setProcessing(true);
     } catch (error) {
       console.error("Failed to send prompt:", error);
       claudeStore.addLine("error", `Failed to send: ${error}`);
@@ -793,6 +794,7 @@ User: ${formattedMessage}`;
         conversationId,
         message: prompt,
       });
+      claudeStore.setProcessing(true);
     } catch (error) {
       console.error("Failed to send quick action:", error);
       claudeStore.addLine("error", `Failed to send: ${error}`);

src/lib/stores/claude.ts

@@ -41,6 +41,7 @@ export const claudeStore = {
   setWorkingDirectory: conversationsStore.setWorkingDirectory,
   setWorkingDirectoryForConversation: conversationsStore.setWorkingDirectoryForConversation,
   setProcessing: conversationsStore.setProcessing,
+  setProcessingForConversation: conversationsStore.setProcessingForConversation,
   addLine: conversationsStore.addLine,
   addLineToConversation: conversationsStore.addLineToConversation,
   updateLine: conversationsStore.updateLine,

src/lib/stores/conversations.test.ts

@@ -561,3 +561,97 @@ describe("draft text persistence", () => {
     expect(conversation.draftText).toBe("");
   });
 });
+
+describe("isProcessing state management", () => {
+  it("starts as false by default", () => {
+    const conversation = { id: "conv-1", isProcessing: false };
+    expect(conversation.isProcessing).toBe(false);
+  });
+
+  it("setProcessingForConversation sets processing true for the target conversation", () => {
+    const conversations = new Map([
+      ["conv-1", { isProcessing: false, lastActivityAt: new Date(0) }],
+      ["conv-2", { isProcessing: false, lastActivityAt: new Date(0) }],
+    ]);
+
+    const setProcessingForConversation = (conversationId: string, processing: boolean) => {
+      const conv = conversations.get(conversationId);
+      if (conv) {
+        conv.isProcessing = processing;
+        conv.lastActivityAt = new Date();
+      }
+    };
+
+    setProcessingForConversation("conv-1", true);
+
+    expect(conversations.get("conv-1")?.isProcessing).toBe(true);
+    expect(conversations.get("conv-2")?.isProcessing).toBe(false);
+  });
+
+  it("setProcessingForConversation resets processing to false", () => {
+    const conversations = new Map([
+      ["conv-1", { isProcessing: true, lastActivityAt: new Date(0) }],
+    ]);
+
+    const setProcessingForConversation = (conversationId: string, processing: boolean) => {
+      const conv = conversations.get(conversationId);
+      if (conv) {
+        conv.isProcessing = processing;
+        conv.lastActivityAt = new Date();
+      }
+    };
+
+    setProcessingForConversation("conv-1", false);
+
+    expect(conversations.get("conv-1")?.isProcessing).toBe(false);
+  });
+
+  it("setProcessingForConversation does nothing for unknown conversation", () => {
+    const conversations = new Map([["conv-1", { isProcessing: false, lastActivityAt: new Date(0) }]]);
+
+    const setProcessingForConversation = (conversationId: string, processing: boolean) => {
+      const conv = conversations.get(conversationId);
+      if (conv) {
+        conv.isProcessing = processing;
+        conv.lastActivityAt = new Date();
+      }
+    };
+
+    setProcessingForConversation("unknown", true);
+
+    expect(conversations.get("conv-1")?.isProcessing).toBe(false);
+  });
+
+  it("isProcessing is cleared when idle state arrives", () => {
+    const conversation = { isProcessing: true, characterState: "thinking" };
+
+    const terminalStates = ["idle", "success", "error"];
+    const handleStateChange = (state: string) => {
+      conversation.characterState = state;
+      if (terminalStates.includes(state)) {
+        conversation.isProcessing = false;
+      }
+    };
+
+    handleStateChange("idle");
+
+    expect(conversation.isProcessing).toBe(false);
+  });
+
+  it("isProcessing stays true during non-terminal states", () => {
+    const conversation = { isProcessing: true, characterState: "thinking" };
+
+    const terminalStates = ["idle", "success", "error"];
+    const handleStateChange = (state: string) => {
+      conversation.characterState = state;
+      if (terminalStates.includes(state)) {
+        conversation.isProcessing = false;
+      }
+    };
+
+    for (const state of ["thinking", "typing", "coding", "searching", "mcp"]) {
+      handleStateChange(state);
+      expect(conversation.isProcessing).toBe(true);
+    }
+  });
+});

src/lib/stores/conversations.ts

@@ -560,6 +560,17 @@ function createConversationsStore() {
       });
     },
 
+    setProcessingForConversation: (conversationId: string, processing: boolean) => {
+      conversations.update((convs) => {
+        const conv = convs.get(conversationId);
+        if (conv) {
+          conv.isProcessing = processing;
+          conv.lastActivityAt = new Date();
+        }
+        return convs;
+      });
+    },
+
     addLine: (
       type: TerminalLine["type"],
       content: string,

src/lib/tauri.ts

@@ -333,13 +333,21 @@ export async function initializeTauriListeners() {
     }
 
     // Always update the conversation's state
+    const isTerminalState =
+      mappedState === "idle" || mappedState === "success" || mappedState === "error";
     if (conversation_id) {
       claudeStore.setCharacterStateForConversation(conversation_id, mappedState);
+      if (isTerminalState) {
+        claudeStore.setProcessingForConversation(conversation_id, false);
+      }
     } else {
       // Fallback to active conversation if no conversation_id
       const activeConversationId = get(claudeStore.activeConversationId);
       if (activeConversationId) {
         claudeStore.setCharacterStateForConversation(activeConversationId, mappedState);
+        if (isTerminalState) {
+          claudeStore.setProcessingForConversation(activeConversationId, false);
+        }
       }
     }