fix(ci): remove pnpm cache from workspace detection job

[alco]

Summary

• The detect_affected_workspaces job in ts_tests.yml had cache: pnpm enabled but doesn't run pnpm install
• This causes a "Path Validation Error" at job completion when the cache path doesn't exist
• Breaks PRs that only touch non-TS files (e.g., Elixir mix.lock updates like Update Elixir deps to latest versions #4255)

Test plan

• Verify the fix by checking that Update Elixir deps to latest versions #4255 passes CI after this is merged

🤖 Generated with Claude Code

cc @icehaunter

[claude]

Claude Code Review

Summary

This is a minimal one-line CI fix that removes the erroneous cache: pnpm setting from the detect_affected_workspaces job's setup-node step. The fix is correct and clearly explained — that job never runs pnpm install, so the cache path doesn't exist, causing the "Path Validation Error" at job completion.

What's Working Well

• The fix is precise: only the offending line is removed with no side effects. Other jobs (typecheck_packages, etc.) that do run pnpm install correctly retain their cache: pnpm setting.
• The PR description accurately diagnoses the root cause and identifies a concrete reproduction case (Update Elixir deps to latest versions #4255).
• Zero risk of regression: removing a cache directive from a node setup step that doesn't install packages has no functional impact.

Issues Found

Critical (Must Fix)

None.

Important (Should Fix)

None.

Suggestions (Nice to Have)

None.

Issue Conformance

No linked GitHub issue. For a one-liner CI fix with a clear reproduction case already cited in the PR description (#4255), this is acceptable — but future CI fixes should ideally reference or create a tracking issue so the context is preserved in the issue tracker.

---

Review iteration: 1 | 2026-05-04

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.61%. Comparing base (38f550c) to head (afe0bb0).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4264   +/-   ##
=======================================
  Coverage   64.61%   64.61%           
=======================================
  Files         144      144           
  Lines       19308    19308           
  Branches     4747     4752    +5     
=======================================
  Hits        12476    12476           
  Misses       6829     6829           
  Partials        3        3           

Flag	Coverage Δ
packages/agents	54.40% <ø> (ø)
packages/agents-runtime	78.61% <ø> (ø)
packages/agents-server	66.03% <ø> (ø)
packages/agents-server-ui	0.00% <ø> (ø)
packages/electric-ax	38.59% <ø> (ø)
packages/experimental	87.73% <ø> (ø)
packages/react-hooks	86.48% <ø> (ø)
packages/start	82.83% <ø> (ø)
packages/typescript-client	94.30% <ø> (ø)
packages/y-electric	56.05% <ø> (ø)
typescript	64.61% <ø> (ø)
unit-tests	64.61% <ø> (ø)

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