ci: gate langchain CD on uv resolvability, not just PyPI simple index

[cosminacho]

Summary

When a single PR bumps both uipath-llm-client and uipath-langchain-client, the cd-langchain job can finish its wait step but still fail the smoke test with Because only uipath-llm-client<=PREV_VERSION is available — even though the new core was already published. See run 25555638070.

Root cause: The wait step polled pypi.org/simple/uipath-llm-client/ with Cache-Control: no-cache, which only confirms PyPI's CDN knows about the new version. It does not mean uv will see it. setup-uv@v7 with enable-cache: true restores uv's metadata cache across job runs, so uv's cached simple-index entry for uipath-llm-client can still show only the previous version. The downstream uv run --with "${WHEEL}[all]" then resolves against that stale cache and fails.

Timing from the failed run:

• 12:31:58 — curl saw uipath-llm-client==1.11.0 on the simple index
• 12:32:07 — uv reported only uipath-llm-client<=1.10.0 is available (9s later)

Fix:

• Move setup-uv and setup-python ahead of the wait step.
• Replace the curl probe with uv pip install --dry-run --refresh-package uipath-llm-client "uipath-llm-client==$CORE_VERSION". --refresh-package invalidates uv's local metadata cache for just that project and forces a fresh fetch on each attempt. Once it succeeds, uv's cache is warm with the new version and downstream smoke tests inherit it.
• Pass --refresh-package uipath-llm-client on the smoke tests as well, as belt-and-suspenders.

This mirrors the approach used in the uipath-python repo's build-package.yml (uv lock --no-sources --no-cache with retries), adapted to our existing wait-then-poll structure.

Only cd-langchain.yml changes — no source changes, no version bump.

Test plan

• Next combined core+langchain bump completes the langchain smoke test on the first attempt
• Langchain-only bumps still skip the wait (no core diff in last commit)

🤖 Generated with Claude Code