# Streaming Updates, Values and Tokens — LangGraph Agents & Multi-Agent Systems

Source: https://www.geekswithgeeks.com/en/langgraph-agents/h-stream

> Show progress to users while a graph runs.

## Do not make users stare at a spinner

Agent runs can take many seconds. `app.stream(input, stream_mode=...)` yields progress as it happens. **`"updates"`** emits only what each node changed (good for step-by-step progress), **`"values"`** emits the full state after every step, **`"messages"`** streams model tokens as they are produced, and **`"custom"`** lets nodes emit their own events (for example "searching the docs..."). You can combine modes. Streaming improves perceived latency, lets users cancel early, and gives you real-time logs. Remember that a streamed answer may later fail validation, so decide what the UI does if the final result is rejected.

## Updates versus values, run

I ran this offline with langgraph 1.2.12 and langchain-core 1.6.6 in a Python virtual environment. No API key or model is needed because plain Python functions stand in for the model, so the output is repeatable. With `stream_mode="updates"` each chunk is the change one node made. With `"values"` each chunk is the whole state: first the input (5), then 10 after `double`, then 11 after `plus_one`.

```python
from typing import TypedDict
from langgraph.graph import StateGraph, START, END

class State(TypedDict):
    n: int

def double(state): return {"n": state["n"] * 2}
def plus_one(state): return {"n": state["n"] + 1}

g = StateGraph(State)
g.add_node("double", double); g.add_node("plus_one", plus_one)
g.add_edge(START, "double"); g.add_edge("double", "plus_one"); g.add_edge("plus_one", END)
app = g.compile()

print("updates:")
for chunk in app.stream({"n": 5}, stream_mode="updates"):
    print("  ", chunk)
print("values:")
for chunk in app.stream({"n": 5}, stream_mode="values"):
    print("  ", chunk)

```

Output:

```
updates:
   {'double': {'n': 10}}
   {'plus_one': {'n': 11}}
values:
   {'n': 5}
   {'n': 10}
   {'n': 11}
```

**Quiz:** Which stream mode emits only what each node changed?

- [ ] values
- [x] updates
- [ ] none
- [ ] checkpoint

*Answer:* updates. "updates" gives per-node deltas; "values" gives the full state each step.