fix(ci): pin the tutorial agents to the local server explicitly

The tutorial tests passed only because the generated client defaulted to
http://localhost:5003. The tutorials' test clients pass base_url
explicitly, but the AGENTS do not: the ADK builds Agentex() and
AsyncAgentex() with no arguments, so they fall back to
ENVIRONMENTS["production"] in _client.py.

That default is wrong, and it shipped. agentex-client 0.28.1 on PyPI
carries "production": "http://localhost:5003", so every user calling
Agentex() is pointed at their own machine. This trunk already corrects it
to https://agentex.sgp.scale.com, matching stainless.yml -- which is why
19 tutorial legs fail on the promote branch while the identical suite
passes on the production trunk (33 passed, 0 failed, dispatched as a
baseline to check exactly this).

So the promote fixes a real bug and these tests were encoding it as
expected behaviour. Pin the local server explicitly rather than reverting
the fix. Agents are plain subprocesses of run_agent_test.sh and inherit
the step environment.

The variable name matters: the SDK reads AGENTEX_BASE_URL, while the
AGENTEX_API_BASE_URL already on the command line is a separate variable
that only the tutorials' own test files read.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: aringuyen3

.github/workflows/agentex-tutorials-test.yml

@@ -169,6 +169,21 @@ jobs:
           CLAUDE_LIVE_TESTS: ${{ contains(matrix.tutorial, 'claude_code') && '1' || '' }}
           CODEX_LIVE_TESTS: ${{ contains(matrix.tutorial, 'codex') && '1' || '' }}
           HEALTH_CHECK_PORT: 8080 # Use non-privileged port for temporal worker health checks
+          # The tutorials' TEST clients pass base_url explicitly, but the AGENTS do not: the
+          # ADK builds Agentex()/AsyncAgentex() with no arguments, so they fall back to
+          # ENVIRONMENTS["production"] in the generated _client.py. That default used to be
+          # http://localhost:5003, which made these tests pass by accident -- and is a real
+          # bug in the published package (agentex-client 0.28.1 ships
+          # "production": "http://localhost:5003", pointing every caller of Agentex() at
+          # their own machine). This trunk corrects it to the real production URL, so pin the
+          # local server explicitly here rather than depending on a default that should never
+          # have been a dev address. Agents are plain subprocesses of run_agent_test.sh and
+          # inherit this.
+          #
+          # Name matters: the SDK reads AGENTEX_BASE_URL. The AGENTEX_API_BASE_URL set on the
+          # command line below is a different variable, read only by the tutorials' own test
+          # files, and never reaches the SDK.
+          AGENTEX_BASE_URL: http://localhost:5003
         run: |
           echo "Testing tutorial: ${{ matrix.tutorial }}"
           AGENTEX_API_BASE_URL="http://localhost:5003" \