diff --git a/src/api/routes.py b/src/api/routes.py
index 0873870..1cc117e 100644
--- a/src/api/routes.py
+++ b/src/api/routes.py
@@ -68,13 +68,15 @@ def set_dependencies(
     context_engine: Any,
     memory_store: Any,
     sse_emitter: Any,
-    mcp_registry: Any,
+    claude_emitter: Any = None,
+    mcp_registry: Any = None,
 ) -> None:
     _deps["storage"] = storage
     _deps["model_adapter"] = model_adapter
     _deps["context_engine"] = context_engine
     _deps["memory_store"] = memory_store
     _deps["sse"] = sse_emitter
+    _deps["claude_sse"] = claude_emitter
     _deps["mcp_registry"] = mcp_registry
 
 
@@ -207,22 +209,33 @@ async def _execute_and_persist(orchestrator, storage, session, message) -> dict[
 # ------------------------------------------------------------------
 
 @router.get("/sessions/{session_id}/stream")
-async def stream_session(session_id: str) -> StreamingResponse:
+async def stream_session(session_id: str, format: str = "native") -> StreamingResponse:
     storage = _get_storage()
     session = await storage.get_session(session_id)
     if not session:
         raise HTTPException(status_code=404, detail="Session not found")
 
-    sse = _get_sse()
+    headers = {
+        "Cache-Control": "no-cache",
+        "Connection": "keep-alive",
+        "X-Accel-Buffering": "no",
+    }
 
+    if format == "claude":
+        claude_sse = _deps.get("claude_sse")
+        if not claude_sse:
+            raise HTTPException(status_code=501, detail="Claude format emitter not available")
+        return StreamingResponse(
+            claude_sse.subscribe(session_id),
+            media_type="text/event-stream",
+            headers=headers,
+        )
+
+    sse = _get_sse()
     return StreamingResponse(
         sse.subscribe(session_id),
         media_type="text/event-stream",
-        headers={
-            "Cache-Control": "no-cache",
-            "Connection": "keep-alive",
-            "X-Accel-Buffering": "no",
-        },
+        headers=headers,
     )
 
 
diff --git a/src/main.py b/src/main.py
index 8f3d583..5fbcdef 100644
--- a/src/main.py
+++ b/src/main.py
@@ -27,6 +27,7 @@ from .mcp.registry import MCPRegistry
 from .memory.store import MemoryStore
 from .orchestrator.engine import OrchestratorEngine
 from .storage.redis import RedisStorage
+from .streaming.claude_format import ClaudeFormatEmitter, DualEmitter
 from .streaming.sse import SSEEmitter
 
 logging.basicConfig(
@@ -38,6 +39,8 @@ logger = logging.getLogger(__name__)
 # Global instances (initialized in lifespan)
 redis_storage = RedisStorage()
 sse_emitter = SSEEmitter(redis_storage=redis_storage)
+claude_emitter = ClaudeFormatEmitter()
+dual_emitter = DualEmitter(sse_emitter, claude_emitter)
 mcp_registry = MCPRegistry()
 
 
@@ -48,7 +51,6 @@ async def lifespan(app: FastAPI):
 
     # 1. Connect Redis
     await redis_storage.connect()
-    sse_emitter.set_storage(redis_storage)
 
     # 2. Initialize model adapter
     if settings.default_model_provider == "openai":
@@ -82,12 +84,14 @@ async def lifespan(app: FastAPI):
     mcp_registry.load_config()
 
     # 6. Wire dependencies (orchestrator is created per-message with session's MCP)
+    dual_emitter.set_storage(redis_storage)
     set_dependencies(
         storage=redis_storage,
         model_adapter=model_adapter,
         context_engine=context_engine,
         memory_store=memory_store,
-        sse_emitter=sse_emitter,
+        sse_emitter=dual_emitter,
+        claude_emitter=claude_emitter,
         mcp_registry=mcp_registry,
     )
 
diff --git a/src/orchestrator/agents/base.py b/src/orchestrator/agents/base.py
index b65c339..b8dd7f9 100644
--- a/src/orchestrator/agents/base.py
+++ b/src/orchestrator/agents/base.py
@@ -115,7 +115,7 @@ class BaseAgent:
                         }
                         await self.sse.emit(
                             EventType.TOOL_STARTED,
-                            {"tool": chunk.tool_name, "step": step},
+                            {"tool": chunk.tool_name, "tool_call_id": chunk.tool_call_id, "step": step},
                             session_id=session.session_id,
                         )
 
@@ -123,6 +123,17 @@ class BaseAgent:
                     tool = active_tools.get(chunk.tool_call_id)
                     if tool:
                         tool["arguments"] += chunk.tool_arguments
+                        await self.sse.emit(
+                            EventType.AGENT_DELTA,
+                            {
+                                "agent": self.profile.role,
+                                "delta": "",
+                                "tool_arguments": chunk.tool_arguments,
+                                "tool_call_id": chunk.tool_call_id,
+                                "step": step,
+                            },
+                            session_id=session.session_id,
+                        )
 
                 if chunk.finish_reason == "tool_use" and chunk.tool_call_id:
                     tool = active_tools.pop(chunk.tool_call_id, None)
@@ -200,6 +211,7 @@ class BaseAgent:
                     tool_name=tc["name"],
                     arguments=tc.get("parsed_arguments", {}),
                     artifacts=artifacts,
+                    tool_call_id=tc["id"],
                 )
                 tool_fingerprints[fp] = tool_exec
                 tool_executions.append(tool_exec)
@@ -253,6 +265,7 @@ class BaseAgent:
         tool_name: str,
         arguments: dict[str, Any],
         artifacts: list[ArtifactSummary],
+        tool_call_id: str = "",
     ) -> ToolExecution:
         """Execute a tool and summarise the result."""
         exec_id = uuid.uuid4().hex[:12]
@@ -299,6 +312,8 @@ class BaseAgent:
                     "tool": tool_name,
                     "status": "completed",
                     "summary": artifact.summary[:200],
+                    "raw_output": raw_output[:4000],
+                    "tool_call_id": tool_call_id,
                 },
                 session_id=session.session_id,
             )
@@ -311,7 +326,7 @@ class BaseAgent:
 
             await self.sse.emit(
                 EventType.TOOL_COMPLETED,
-                {"tool": tool_name, "status": "failed", "error": str(e)},
+                {"tool": tool_name, "status": "failed", "error": str(e), "tool_call_id": tool_call_id},
                 session_id=session.session_id,
             )
 
diff --git a/src/orchestrator/engine.py b/src/orchestrator/engine.py
index 07d8b88..b89ffa8 100644
--- a/src/orchestrator/engine.py
+++ b/src/orchestrator/engine.py
@@ -223,18 +223,6 @@ class OrchestratorEngine:
         final_content = self._assemble_response(results, review_result)
         status = "completed" if not failed_steps else "partial"
 
-        await self.sse.emit(
-            EventType.EXECUTION_COMPLETED,
-            {
-                "session_id": session.session_id,
-                "task_id": task.task_id,
-                "steps_completed": len(results),
-                "steps_failed": failed_steps,
-                "status": status,
-            },
-            session_id=session.session_id,
-        )
-
         # Accumulate token usage: planner + all steps + review
         total_input = planner_usage.get("input_tokens", 0)
         total_output = planner_usage.get("output_tokens", 0)
@@ -250,6 +238,23 @@ class OrchestratorEngine:
             + (total_output / 1_000_000) * settings.cost_per_1m_output
         )
 
+        await self.sse.emit(
+            EventType.EXECUTION_COMPLETED,
+            {
+                "session_id": session.session_id,
+                "task_id": task.task_id,
+                "steps_completed": len(results),
+                "steps_failed": failed_steps,
+                "status": status,
+                "usage": {
+                    "input_tokens": total_input,
+                    "output_tokens": total_output,
+                },
+                "total_cost_usd": round(cost_usd, 6),
+            },
+            session_id=session.session_id,
+        )
+
         return {
             "session_id": session.session_id,
             "task_id": task.task_id,
diff --git a/src/streaming/claude_format.py b/src/streaming/claude_format.py
new file mode 100644
index 0000000..8518a51
--- /dev/null
+++ b/src/streaming/claude_format.py
@@ -0,0 +1,321 @@
+"""Claude Code CLI compatible SSE format emitter.
+
+Translates agenticSystem native events into the exact format that
+Claude Code CLI produces, so the frontend can consume them without
+any changes. Used via ?format=claude on the stream endpoint.
+
+Wire format: data: {json}\n\n (no event: or id: fields)
+"""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import logging
+from typing import Any, AsyncIterator
+
+from .sse import EventType, SSEEmitter
+
+logger = logging.getLogger(__name__)
+
+
+class ClaudeFormatEmitter:
+    """Emits events in Claude Code CLI SSE format.
+
+    Maintains per-session state to track block indices and
+    accumulate content for assistant snapshots.
+    """
+
+    def __init__(self) -> None:
+        self._queues: dict[str, list[asyncio.Queue[str | None]]] = {}
+        # Per-session state
+        self._block_counter: dict[str, int] = {}
+        self._text_block_open: dict[str, bool] = {}
+        self._text_block_index: dict[str, int] = {}
+        self._tool_block_index: dict[str, dict[str, int]] = {}  # session -> {tool_call_id -> index}
+        self._content_blocks: dict[str, list[dict[str, Any]]] = {}
+        self._text_accumulator: dict[str, str] = {}
+
+    def _next_index(self, session_id: str) -> int:
+        idx = self._block_counter.get(session_id, 0)
+        self._block_counter[session_id] = idx + 1
+        return idx
+
+    def _reset_session(self, session_id: str) -> None:
+        self._block_counter[session_id] = 0
+        self._text_block_open[session_id] = False
+        self._text_block_index[session_id] = -1
+        self._tool_block_index[session_id] = {}
+        self._content_blocks[session_id] = []
+        self._text_accumulator[session_id] = ""
+
+    def _push(self, session_id: str, payload: dict[str, Any]) -> None:
+        """Push a formatted line to all subscribers of a session."""
+        line = f"data: {json.dumps(payload, ensure_ascii=False)}\n\n"
+        for q in self._queues.get(session_id, []):
+            try:
+                q.put_nowait(line)
+            except asyncio.QueueFull:
+                logger.warning("Claude SSE queue full for session %s", session_id[:8])
+
+    def _close_text_block(self, session_id: str) -> None:
+        """Close the current open text block if any."""
+        if self._text_block_open.get(session_id):
+            idx = self._text_block_index[session_id]
+            self._push(session_id, {
+                "type": "stream_event",
+                "event": {"type": "content_block_stop", "index": idx},
+            })
+            # Save accumulated text to content blocks
+            text = self._text_accumulator.get(session_id, "")
+            if text:
+                self._content_blocks.setdefault(session_id, []).append({
+                    "type": "text", "text": text,
+                })
+            self._text_block_open[session_id] = False
+            self._text_accumulator[session_id] = ""
+
+    def _open_text_block(self, session_id: str) -> None:
+        """Open a new text block."""
+        idx = self._next_index(session_id)
+        self._text_block_index[session_id] = idx
+        self._text_block_open[session_id] = True
+        self._text_accumulator[session_id] = ""
+        self._push(session_id, {
+            "type": "stream_event",
+            "event": {
+                "type": "content_block_start",
+                "index": idx,
+                "content_block": {"type": "text", "text": ""},
+            },
+        })
+
+    def _build_assistant_snapshot(self, session_id: str) -> dict[str, Any]:
+        """Build assistant message snapshot for reconciliation."""
+        blocks = list(self._content_blocks.get(session_id, []))
+        return {
+            "type": "assistant",
+            "message": {"content": blocks},
+            "error": False,
+        }
+
+    async def emit(
+        self,
+        event_type: EventType,
+        data: dict[str, Any],
+        session_id: str,
+    ) -> None:
+        """Translate a native event into Claude Code CLI format."""
+
+        if event_type == EventType.EXECUTION_STARTED:
+            self._reset_session(session_id)
+            self._push(session_id, {
+                "type": "stream_event",
+                "event": {"type": "message_start"},
+            })
+
+        elif event_type == EventType.AGENT_DELTA:
+            delta_text = data.get("delta", "")
+            tool_args = data.get("tool_arguments", "")
+            tool_call_id = data.get("tool_call_id", "")
+
+            if delta_text:
+                # Text streaming
+                if not self._text_block_open.get(session_id):
+                    self._open_text_block(session_id)
+                idx = self._text_block_index[session_id]
+                self._text_accumulator[session_id] = self._text_accumulator.get(session_id, "") + delta_text
+                self._push(session_id, {
+                    "type": "stream_event",
+                    "event": {
+                        "type": "content_block_delta",
+                        "index": idx,
+                        "delta": {"type": "text_delta", "text": delta_text},
+                    },
+                })
+
+            elif tool_args and tool_call_id:
+                # Tool input JSON streaming
+                tool_indices = self._tool_block_index.get(session_id, {})
+                idx = tool_indices.get(tool_call_id)
+                if idx is not None:
+                    self._push(session_id, {
+                        "type": "stream_event",
+                        "event": {
+                            "type": "content_block_delta",
+                            "index": idx,
+                            "delta": {"type": "input_json_delta", "partial_json": tool_args},
+                        },
+                    })
+
+        elif event_type == EventType.TOOL_STARTED:
+            tool_name = data.get("tool", "unknown")
+            tool_call_id = data.get("tool_call_id", "")
+
+            # Close open text block
+            self._close_text_block(session_id)
+
+            # Open tool_use block
+            idx = self._next_index(session_id)
+            self._tool_block_index.setdefault(session_id, {})[tool_call_id] = idx
+            self._push(session_id, {
+                "type": "stream_event",
+                "event": {
+                    "type": "content_block_start",
+                    "index": idx,
+                    "content_block": {
+                        "type": "tool_use",
+                        "name": tool_name,
+                        "id": tool_call_id,
+                    },
+                },
+            })
+
+        elif event_type == EventType.TOOL_COMPLETED:
+            tool_name = data.get("tool", "unknown")
+            tool_call_id = data.get("tool_call_id", "")
+            status = data.get("status", "completed")
+            raw_output = data.get("raw_output", data.get("summary", ""))
+            is_error = status == "failed"
+
+            # Close tool_use block
+            tool_indices = self._tool_block_index.get(session_id, {})
+            idx = tool_indices.get(tool_call_id)
+            if idx is not None:
+                self._push(session_id, {
+                    "type": "stream_event",
+                    "event": {"type": "content_block_stop", "index": idx},
+                })
+
+            # Save tool_use to content blocks for snapshot
+            self._content_blocks.setdefault(session_id, []).append({
+                "type": "tool_use",
+                "id": tool_call_id,
+                "name": tool_name,
+                "input": {},
+            })
+
+            # Emit tool_result
+            content = data.get("error", raw_output) if is_error else raw_output
+            self._push(session_id, {
+                "type": "tool_result",
+                "tool_use_id": tool_call_id,
+                "content": content[:4000] if isinstance(content, str) else str(content)[:4000],
+                "is_error": is_error,
+            })
+
+            # Emit assistant snapshot for reconciliation
+            self._push(session_id, self._build_assistant_snapshot(session_id))
+
+        elif event_type == EventType.EXECUTION_COMPLETED:
+            # Close any open text block
+            self._close_text_block(session_id)
+
+            # Final assistant snapshot
+            self._push(session_id, self._build_assistant_snapshot(session_id))
+
+            # Result with usage
+            usage = data.get("usage", {})
+            self._push(session_id, {
+                "type": "result",
+                "is_error": False,
+                "usage": {
+                    "input_tokens": usage.get("input_tokens", 0),
+                    "output_tokens": usage.get("output_tokens", 0),
+                    "cache_read_input_tokens": 0,
+                    "cache_creation_input_tokens": 0,
+                },
+                "total_cost_usd": data.get("total_cost_usd", 0),
+            })
+
+            # Done
+            self._push(session_id, {"type": "done"})
+
+        elif event_type == EventType.ERROR:
+            error_msg = data.get("message", str(data.get("error", "Unknown error")))
+
+            # Close any open block
+            self._close_text_block(session_id)
+
+            self._push(session_id, {
+                "type": "result",
+                "is_error": True,
+                "result": error_msg,
+                "usage": {"input_tokens": 0, "output_tokens": 0, "cache_read_input_tokens": 0, "cache_creation_input_tokens": 0},
+                "total_cost_usd": 0,
+            })
+            self._push(session_id, {"type": "done"})
+
+        # Ignore other event types (KEEPALIVE, SESSION_CREATED, SUBAGENT_ASSIGNED)
+
+    async def subscribe(self, session_id: str) -> AsyncIterator[str]:
+        """Subscribe to Claude-format SSE events for a session."""
+        queue: asyncio.Queue[str | None] = asyncio.Queue(maxsize=512)
+
+        if session_id not in self._queues:
+            self._queues[session_id] = []
+        self._queues[session_id].append(queue)
+
+        try:
+            while True:
+                try:
+                    line = await asyncio.wait_for(queue.get(), timeout=15.0)
+                    if line is None:
+                        break
+                    yield line
+                except asyncio.TimeoutError:
+                    yield 'data: {"type":"keepalive"}\n\n'
+        finally:
+            if queue in self._queues.get(session_id, []):
+                self._queues[session_id].remove(queue)
+
+    def cleanup_session(self, session_id: str) -> None:
+        """Clean up session state and close subscribers."""
+        for q in self._queues.get(session_id, []):
+            try:
+                q.put_nowait(None)
+            except asyncio.QueueFull:
+                pass
+        self._queues.pop(session_id, None)
+        self._block_counter.pop(session_id, None)
+        self._text_block_open.pop(session_id, None)
+        self._text_block_index.pop(session_id, None)
+        self._tool_block_index.pop(session_id, None)
+        self._content_blocks.pop(session_id, None)
+        self._text_accumulator.pop(session_id, None)
+
+
+class DualEmitter:
+    """Wraps SSEEmitter (native) + ClaudeFormatEmitter.
+
+    Agents call emit() and both formats are produced.
+    Duck-type compatible with SSEEmitter.
+    """
+
+    def __init__(self, native: SSEEmitter, claude: ClaudeFormatEmitter) -> None:
+        self.native = native
+        self.claude = claude
+
+    async def emit(
+        self,
+        event_type: EventType,
+        data: dict[str, Any],
+        session_id: str,
+    ) -> None:
+        await self.native.emit(event_type, data, session_id)
+        await self.claude.emit(event_type, data, session_id)
+
+    # Delegate native SSE methods for backward compatibility
+    async def subscribe(self, session_id: str) -> AsyncIterator[str]:
+        async for line in self.native.subscribe(session_id):
+            yield line
+
+    async def get_history(self, session_id: str) -> list[dict[str, Any]]:
+        return await self.native.get_history(session_id)
+
+    def cleanup_session(self, session_id: str) -> None:
+        self.native.cleanup_session(session_id)
+        self.claude.cleanup_session(session_id)
+
+    def set_storage(self, redis_storage: Any) -> None:
+        self.native.set_storage(redis_storage)