[Skills] Add Buildkite logs skill

.agents/skills/buildkite-logs/SKILL.md

@@ -0,0 +1,133 @@
+---
+name: buildkite-logs
+description: >-
+  Fetch and analyse Buildkite CI logs for the elastic/kibana repo. Provides
+  helpers to retrieve build/job logs by build number or PR number, summarise
+  failures, and inspect artifacts. Use when the user asks about CI failures,
+  Buildkite logs, a failing build, a red CI, build artifacts, or mentions a
+  Buildkite URL or PR number in the context of CI.
+---
+
+# Buildkite Logs
+
+## Authentication
+
+All requests require `BUILDKITE_API_TOKEN`. The token is read-only for most
+operations; a read-write token is needed to trigger retries.
+
+```bash
+# Check for token
+if [ -z "$BUILDKITE_API_TOKEN" ]; then
+  echo "Set BUILDKITE_API_TOKEN before proceeding."
+  exit 1
+fi
+BK_AUTH="Authorization: Bearer $BUILDKITE_API_TOKEN"
+ORG="elastic"
+PIPELINE="kibana-pull-request"
+BASE="https://api.buildkite.com/v2"
+```
+
+If the token is missing, ask the user to export it:
+> You can create a token at https://buildkite.com/user/api-access-tokens (scope: read_builds, read_artifacts).
+
+---
+
+## Fetch build by number
+
+```bash
+BUILD_NUMBER=<number>
+curl -sf -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds/$BUILD_NUMBER" \
+  | jq '{number,state,branch,commit,created_at,web_url,jobs:[.jobs[]|{id,name,state,exit_status,web_url}]}'
+```
+
+To get a build number from a Buildkite URL like
+`https://buildkite.com/elastic/kibana-pull-request/builds/414685`, extract `414685`.
+
+---
+
+## Fetch latest build for a PR
+
+```bash
+PR=<number>
+curl -sf -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds?pull_request_id=$PR&per_page=1" \
+  | jq '.[0] | {number,state,branch,web_url,jobs:[.jobs[]|{id,name,state,exit_status}]}'
+```
+
+---
+
+## Fetch job log
+
+Once you have a build number and job ID:
+
+```bash
+BUILD_NUMBER=<number>
+JOB_ID=<uuid>
+curl -sf -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds/$BUILD_NUMBER/jobs/$JOB_ID/log" \
+  | jq -r '.content'
+```
+
+Logs can be large. Pipe through `tail -n 200` or search with `grep`/`rg` for
+relevant sections:
+
+```bash
+... | jq -r '.content' | grep -A 5 -i "error\|fail\|FAIL\|exception"
+```
+
+---
+
+## Workflow: diagnose a failing build
+
+1. **Get build overview** (fetch build by number or PR, see above).
+2. **Identify failed jobs**: filter `jobs` where `state == "failed"`.
+3. **Fetch log for each failed job** and search for the first error/failure.
+4. **Summarise**: report job name, exit code, and the key error lines.
+
+For large logs, focus on the last 200–500 lines plus any lines matching
+`error`, `FAIL`, `AssertionError`, `TypeError`, or `✖`.
+
+---
+
+## Workflow: understand job definition for PR build
+1. Analyse .buildkite/pipelines/pull_request/base.yml
+2. Analyse any relevant yml files in the folder
+
+## List and download artifacts
+
+```bash
+BUILD_NUMBER=<number>
+# List artifacts for the build
+curl -sf -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds/$BUILD_NUMBER/artifacts" \
+  | jq '.[] | {id,filename,file_size,download_url}'
+
+# Download a specific artifact
+ARTIFACT_ID=<uuid>
+curl -sL -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds/$BUILD_NUMBER/artifacts/$ARTIFACT_ID/download" \
+  -o <filename>
+```
+
+Artifacts for a single job:
+```bash
+JOB_ID=<uuid>
+curl -sf -H "$BK_AUTH" \
+  "$BASE/organizations/$ORG/pipelines/$PIPELINE/builds/$BUILD_NUMBER/jobs/$JOB_ID/artifacts" \
+  | jq '.[] | {id,filename,file_size,download_url}'
+```
+
+---
+
+## Other pipelines
+
+Kibana has multiple pipelines. Common slugs:
+
+| Pipeline | Slug |
+|---|---|
+| PR | `kibana-pull-request` |
+| On-merge | `kibana-on-merge` |
+| Flaky test runner | `kibana-flaky-test-suite-runner` |
+
+Substitute the `PIPELINE` variable as needed.

.github/CODEOWNERS

@@ -3230,6 +3230,7 @@ x-pack/solutions/observability/plugins/synthetics/server/saved_objects/synthetic
 /.agents/skills/scout-migrate-from-ftr/** @elastic/appex-qa
 /.agents/skills/scout-ui-testing/** @elastic/appex-qa
 /.agents/skills/enzyme-to-rtl/** @elastic/appex-qa
+/.agents/skills/buildkite-logs @elastic/appex-qa
 /.agents/skills/evals-create-suite/** @elastic/obs-ai-team @elastic/security-generative-ai
 /.agents/skills/evals-write-spec/** @elastic/obs-ai-team @elastic/security-generative-ai