fix: Example hello_world.py Context naming

[kthui]

Overview:

PyContext should be named Context in Python.

Details:

Before:

/workspace/examples/runtime/hello_world$ python hello_world.py
Traceback (most recent call last):
  File "/workspace/examples/runtime/hello_world/hello_world.py", line 21, in <module>
    from dynamo.runtime import PyContext, DistributedRuntime, dynamo_endpoint, dynamo_worker
ImportError: cannot import name 'PyContext' from 'dynamo.runtime' (/opt/dynamo/venv/lib/python3.12/site-packages/dynamo/runtime/__init__.py). Did you mean: 'Context'?

After:

/workspace/examples/runtime/hello_world$ python hello_world.py
2025-09-03T17:34:28.864169Z  INFO hello_world.worker: [backend] Created service hello_world/backend   
2025-09-03T17:34:28.864216Z  INFO hello_world.worker: [backend] Serving endpoint generate on lease 7587889230630619401

Where should the reviewer start?

N/A

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

N/A

Summary by CodeRabbit

• New Features

  • Hello World example now streams output incrementally instead of returning a single response.
  • Supports cancelling/stop requests mid-response to end streaming gracefully.

• Behavior Changes

  • Responses are emitted per word with short delays, improving perceived responsiveness for longer inputs.

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[coderabbitai]

Walkthrough

The hello_world runtime example updates its import and function signature to use Context instead of PyContext, converts content_generator into an async generator that streams per-word greetings with 1-second delays, and adds cancellation checks (is_stopped/is_killed) after each delay.

Changes

Cohort / File(s)	Summary
Hello world runtime example examples/runtime/hello_world/hello_world.py	Replace PyContext with Context in imports and function signature; convert content_generator into an async generator that yields per-word "Hello {word}!" with 1s delay; add cancellation checks (is_stopped/is_killed) after sleep; existing logging retained.

Sequence Diagram(s)

sequenceDiagram
    autonumber
    actor Client
    participant Endpoint as dynamo_endpoint
    participant Worker as dynamo_worker
    participant Gen as content_generator
    participant Ctx as Context

    Client->>Endpoint: HTTP request (text)
    Endpoint->>Worker: Invoke handler(request)
    Worker->>Gen: Start async generator(request, Ctx)
    loop for each word in request
        Gen->>Gen: await sleep(1s)
        Gen->>Ctx: check is_stopped()/is_killed()
        alt Cancellation detected
            Gen-->>Worker: return (stop streaming)
            Note right of Gen: Prints cancellation message
        else Continue
            Gen-->>Worker: yield "Hello {word}!"
            Worker-->>Endpoint: stream chunk
            Endpoint-->>Client: send chunk
        end
    end
    Worker-->>Endpoint: complete
    Endpoint-->>Client: end of stream

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

I twitch my ears at each hello I send,
One hop per word, a greeting without end.
If winds cry “stop,” I pause mid-beat—
Streams go quiet, soft and sweet.
Then off I scamper, code left neat. 🐇✨

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

examples/runtime/hello_world/hello_world.py (1)

29-36: Minor polish: early-cancel check, trim tokens, use logger over print, and add return type.
Keeps behavior identical while improving UX and consistency.

Apply this diff:

-async def content_generator(request: str, context: Context):
+async def content_generator(request: str, context: Context) -> "AsyncGenerator[str, None]":
@@
-    for word in request.split(","):
-        await asyncio.sleep(1)
-        if context.is_stopped() or context.is_killed():
-            print("request got cancelled.")
-            return
-        yield f"Hello {word}!"
+    for word in (w.strip() for w in request.split(",") if w.strip()):
+        # Skip unnecessary sleep if already cancelled
+        if context.is_stopped() or context.is_killed():
+            logger.info("Request cancelled; id=%s", context.id())
+            return
+        await asyncio.sleep(1)
+        if context.is_stopped() or context.is_killed():
+            logger.info("Request cancelled; id=%s", context.id())
+            return
+        yield f"Hello {word}!"

Add this import near the top:

from typing import AsyncGenerator

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📥 Commits

Reviewing files that changed from the base of the PR and between 5c197b3 and 91c5423.

📒 Files selected for processing (1)

• examples/runtime/hello_world/hello_world.py (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

examples/runtime/hello_world/hello_world.py (2)

lib/bindings/python/src/dynamo/_core.pyi (1)

• DistributedRuntime (31-54)

lib/bindings/python/src/dynamo/runtime/__init__.py (2)

• dynamo_endpoint (65-97)
• dynamo_worker (36-62)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: Build and Test - dynamo

🔇 Additional comments (2)

examples/runtime/hello_world/hello_world.py (2)

28-29: Double-check response_model type compatibility with dynamo_endpoint.
Decorator signature expects response_model: Type[BaseModel]; passing str may break once response validation is implemented. If strings are intended, confirm the API supports this long-term or switch the example to a simple Pydantic model.

---

21-21: Verify Context API and stale references

• No leftover PyContext imports or usage detected in the codebase.
• Confirm that Context from dynamo._core provides the methods id(), is_stopped(), and is_killed().

[nealvaidya]

LGTM