Send Python SDK user agent on control-plane requests

[chirag03k]

Summary

• Add the Python SDK User-Agent to the generated control-plane client during autoload
• Keep sending Blaxel-Version for paginated control-plane endpoints
• Cover the autoload header behavior in tests

Why

Sandbox creation through the Python SDK was reaching PostHog as request_origin=api with request_user_agent=python-httpx/..., so backend observability could not extract sdk-version or sdk-language=python.

Tests

• pytest tests/core/test_environment.py tests/core/test_settings_api_version.py -q
• ruff format --check src/blaxel/core/common/autoload.py tests/core/test_environment.py
• ruff check src/blaxel/core/common/autoload.py tests/core/test_environment.py

---

Note

Adds the Python SDK User-Agent header to the generated control-plane client during autoload, alongside the existing Blaxel-Version header. Adds a test verifying both headers are set.

^{Written by Mendral for commit 9379bb6.}

[mendral-app]

🧪 Testing Guide

What this PR addresses

The Python SDK's control-plane HTTP client (used for sandbox creation, etc.) was not sending the SDK-specific User-Agent header. This caused backend observability (PostHog) to see requests as generic python-httpx/<version> instead of blaxel/sdk/python/<version>, making it impossible to extract SDK name or version from telemetry data.

Steps to reproduce the original issue

1. Before this PR, inspect the headers sent by the control-plane client after autoload() runs.
2. Observe that User-Agent is not explicitly set — httpx defaults to python-httpx/x.y.z.
3. In PostHog (or equivalent backend telemetry), SDK-originated requests are indistinguishable from raw httpx calls.

What to verify (expected behavior)

1. Run the new test:

   pytest tests/core/test_environment.py::test_autoload_sets_control_plane_user_agent -q

   It should pass, confirming the client carries both Blaxel-Version and a User-Agent starting with blaxel/sdk/python/.

2. Run the existing settings test to check for regressions:

   pytest tests/core/test_environment.py tests/core/test_settings_api_version.py -q

3. Lint check (no formatting/style regressions):

   ruff format --check src/blaxel/core/common/autoload.py tests/core/test_environment.py
   ruff check src/blaxel/core/common/autoload.py tests/core/test_environment.py

4. Verify the User-Agent value is sourced from settings.headers["User-Agent"] — the same header already used for other SDK requests — ensuring consistency across all outbound traffic.

Note

Posted by PR Testing Guide · Tag @mendral-app with feedback.

[mendral-app]

Interaction Flow

sequenceDiagram
    participant App as Application
    participant AL as autoload()
    participant Settings as settings
    participant Client as client (httpx)
    participant CP as Control Plane API

    App->>AL: autoload()
    AL->>Settings: read base_url, auth
    AL->>Settings: read api_version
    AL->>Settings: read headers["User-Agent"]
    AL->>Client: with_headers({"Blaxel-Version": ..., "User-Agent": ...})
    Client->>CP: HTTP request
    Note right of CP: Headers now include:<br/>Blaxel-Version: 2026-04-28<br/>User-Agent: blaxel/sdk/python/x.y.z
    CP-->>CP: PostHog observability<br/>classifies SDK traffic

Loading

Summary: The autoload() function now propagates the Python SDK User-Agent header (alongside the existing Blaxel-Version) from settings into the control-plane client. This lets backend observability (PostHog) distinguish Python SDK traffic from generic python-httpx requests.

Note

Posted by PR Sequence Diagram · Tag @mendral-app with feedback.

[mendral-app]

LGTM

Change is minimal and correct. settings.headers["User-Agent"] is evaluated once at autoload time and stored as a static header—no repeated property evaluation or auth-token leakage risk. The riskiest aspect (accidentally sending auth headers via settings.headers) is avoided because only the User-Agent key is extracted explicitly.

_{Tag @mendral-app with feedback or questions. View session}

[mendral-app]

✅ Linked to Linear issue ENG-3781 — status: In Review

Note

Posted by Linear Issue Enforcer · Tag @mendral-app with feedback.

[chirag03k]

This is complementary to https://github.com/blaxel-ai/controlplane/pull/4816 which sends tracks SDK information, among other things, upon sandbox creation.