ci(ui): only run the UI build when dashboard files change

[ryan-crabbe-berri]

Relevant issues

Linear ticket

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have added meaningful tests
• My PR passes all CI/CD checks (e.g., lint, format, unit tests)
• My PR's scope is as isolated as possible; it only solves 1 specific problem
• I have received a Greptile Confidence Score of at least 4/5 before requesting a maintainer review (Greptile reviews automatically once the PR is opened; only comment @greptileai to re-request a review after pushing changes)

Screenshots / Proof of Fix

The build-ui job ran a full npm ci + npm run build (a ~10-minute next build) on every PR, backend-only ones included, even though nothing it builds had changed. This gates it the same way frontend-lint already gates itself: the job still runs on every PR so the required check reports a result and never strands, but the install and build steps only execute when a file under ui/litellm-dashboard/ actually changed.

The detection step runs from the job's working-directory (ui/litellm-dashboard), so git diff --name-only "$BASE_SHA"...HEAD -- . is already scoped to the dashboard; it needs fetch-depth: 0 on the checkout so the base commit is present for the diff.

Behavior:

PR touches ui/litellm-dashboard/**   -> ui_changed=true  -> Setup + npm ci + npm run build run (unchanged)
PR touches only backend/docs         -> ui_changed=false -> steps skipped, job reports success in seconds

This is a CI-only change; the logic mirrors the existing frontend-lint job in the same repo, and both workflow files parse as valid YAML.

Type

🚄 Infrastructure

Changes

Add a "Detect UI changes" step to build-ui and gate Setup Node, Install dependencies, and Build on its ui_changed output. Add fetch-depth: 0 to the checkout so the PR base commit is available to diff against.

The job intentionally still runs on every PR rather than using a workflow-level paths: filter; a paths: filter would leave the required check pending forever on PRs that don't touch the UI, which is the stranding problem this repo already solved for backend tests in #32532. Keeping the job and gating its steps avoids that.

[greptile-apps]

Greptile Summary

This CI-only change optimises the build-ui job by adding a "Detect UI changes" step that short-circuits the expensive npm ci + next build path when no files under ui/litellm-dashboard/ have changed. The approach deliberately keeps the job running on every PR (avoiding the required-check stranding problem) and gates only the costly steps via steps.changed.outputs.ui_changed.

• Adds fetch-depth: 0 to the build-ui checkout so the base commit is available for the three-dot git diff, mirroring the pattern already in frontend-lint.
• The detection shell script pipes git diff --name-only \"$BASE_SHA\"...HEAD -- . through grep -q .; since the working-directory is ui/litellm-dashboard, the -- . pathspec is automatically scoped to the dashboard subtree.

Confidence Score: 4/5

Safe to merge — the change is purely additive to a CI workflow and cannot affect production code.

The implementation correctly mirrors the existing frontend-lint job's change-detection pattern. The one edge case worth noting is that a git diff failure would silently fall through to ui_changed=false and skip the build rather than failing the step, but fetch-depth: 0 makes that scenario very unlikely in practice.

No files require special attention beyond the single workflow file changed.

Important Files Changed

Filename	Overview
.github/workflows/test-litellm-ui-build.yml	Adds a "Detect UI changes" step to the build-ui job to skip expensive npm ci + next build steps when no dashboard files changed; mirrors the existing frontend-lint job pattern with fetch-depth: 0 and a git diff guard.

_{Reviews (1): Last reviewed commit: "ci(ui): only run the UI build when dashb..." | Re-trigger Greptile}

[greptile-apps]

Silent git failure sets ui_changed=false

GitHub Actions uses bash -eo pipefail by default, but if pipeline; then absorbs the pipeline's exit code rather than propagating it as a script error. If git diff were to fail (e.g., BASE_SHA not in the fetched history despite fetch-depth: 0), the pipeline exits non-zero, the else branch fires, and ui_changed=false is written — silently skipping the build even when dashboard files did change. fetch-depth: 0 makes this scenario unlikely, and the existing frontend-lint job uses the same pattern, so this is a minor robustness note rather than a blocking concern.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[codspeed-hq]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

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_{Comparing litellm_ui_build_gate (6174210) with litellm_internal_staging (11aeeea)¹}

Footnotes

1. No successful run was found on litellm_internal_staging (b9008cc) during the generation of this report, so 11aeeea was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[ryan-crabbe-berri]

Folding this into #32810; the build-ui gating and the lint-workflow split touch the same file and are one concern, so they belong in a single PR.