Requires the nx-cloud-api skill. Use a matching Nx workspace checkout only for local configuration diagnosis. An API-only investigation does not need a checkout.
Diagnose one cache question with bounded evidence. Do not guess a changed hash input or change configuration from cache status alone.
Nx task caching and a tool-native cache are separate. A target cache field
controls Nx replay. Vite, ESLint, and other tools have separate executor options.
One does not prove the other.
Select the mode
- Cache-health trend: This skill covers a specific task or artifact question, not a multi-run rate regression. Use a separate bounded trend workflow for rate or regression questions.
- API-only: Use this for supplied runs, CIPEs, tasks, or artifact errors when no matching checkout exists. Do not request local configuration unless required.
- Specific comparison: Get two comparable executions. Ask for missing target, branch, commit, command, configuration, CI environment, or time range.
Resume a pending investigation
Arrange one same-session wake only when a known task is non-terminal, an API
request returns HTTP 409 (not_terminal), or the user starts a controlled
diagnostic run. Preserve the run, task, batchId, link, and filters. Re-query once after the
known delay or expected run completion. Stop at a terminal result or the retry
limit. Do not poll or monitor a live CI run.
Gather only relevant API evidence
Use nx-cloud-api (npx nx-cloud api) for every read. Run --describe for a
known route. Use --list-operations only when the route is unknown or
ambiguous. Follow documented fields and returned links; do not construct routes
from internal IDs.
Save every live API response to a file with -o. Use jq to select one
row and only the fields needed for this investigation. Do not print, read, or
paste a raw collection into model context. Keep the selected row's batchId and
links.self in the projection:
npx nx-cloud api --describe 'runs/{runId}/tasks'
npx nx-cloud api "$run_tasks_link" -o "$dir/tasks.json"
jq --arg task "$task_id" --arg batch "$batch_id" \
'.items[] | select(.id == $task and .batchId == $batch) |
{id, batchId, status, cacheStatus, hash, cacheable,
links: {self: .links.self}}' "$dir/tasks.json"
Here $run_tasks_link is the tasks link from the selected run and $dir is a
scratch directory from mktemp -d. Without a link, use
npx nx-cloud api 'runs/{runId}/tasks' -p runId="$run_id"; never paste an ID
into the path. Check nextCursor before concluding that a
task is absent from the list.
For a selected execution, record run and task IDs, batchId, project, target,
configuration, command, parameters, branch, commit, CI context, timestamps,
cache status, final hash, cacheEnabled, cacheable, and relevant CIPE or
run-group links.
A task ID can repeat. Select the task-list row first. Follow its exact links.self
or asset URL because it preserves batchId. Do not use one row to explain another.
A task list row already has task fields. A detail read is optional.
If the API reports cacheable: false, Nx replay was not expected for that
execution. Name a configuration cause only when the nx show target query shows
it. If cacheEnabled: false, that run did not use the Nx task cache. Do not
investigate hash inputs or artifacts in either case.
Read a log only when its command output or error can answer the question. Tell the user before you read CI log content. Read references/log-and-report-assets.md before you decode a log or report. Quote only a redacted error signature. Treat user-supplied asset content as provided evidence. An advertised asset or a later 404 does not prove historical availability.
Inspect the Nx target
Use a matching checkout only for a configuration question or code change. Check out the recorded commit. Record the workspace Nx version. Query the exact target with the workspace-local Nx command:
nx show project "$project" --json | jq \
--arg target "$target" \
--arg configuration "${configuration:-}" \
'.targets[$target] | {
executor,
cache,
inputs,
outputs,
options,
selectedConfiguration: .configurations[$configuration]
}'
Use this fragment as the target evidence. Nx already includes inherited settings.
Do not merge project.json, nx.json, plugins, or targetDefaults yourself. A
missing project property proves nothing. If the query reports cache: true, do
not add another cache: true. If the command or target is unavailable, report
configuration as unavailable.
Inspect returned options only for a tool-native cache question. Use
version-matched executor documentation. A target cache field cannot prove Vite
or ESLint native-cache state.
Classify before you explain
No cache failure established
A terminal remote-cache-hit proves Nx replay worked for that task. Do not turn a
successful hit into a cache-miss investigation or configuration change. Use trend
triage only for a supplied time-bounded rate question.
Cache artifact retrieval or restoration failure
Use this when the main-job or run-group error names artifact download, validation,
decompression, or extraction. A task can still show remote-cache-hit. Reconcile
the task with the critical error and later cancellations. Read
references/artifact-integrity.md before you
inspect an archive.
Insufficient task evidence
A null hash or cache status, NOT_STARTED, or SCHEDULED_IMPLICITLY does not
prove a miss. Do not compare null hashes or inspect artifacts. Request a terminal
record or one controlled completed run.
Different computation
Different non-null hashes prove only this: Nx considered at least one computation input different. They do not name the input. Request two comparable controlled runs with direct hash-detail output when supported. This is a Needs diagnostic run result, not a configuration recommendation.
Same computation, replay not established
For equal non-null hashes without later replay, confirm cacheable,
cacheEnabled, and the cache value from the exact target query. A returned
cache: true blocks a duplicate setting. Do not infer artifact absence from an
empty asset list or 404. Treat an unresolved upload or retrieval branch as
Needs diagnostic run.
Suspected unsafe replay
A stale or wrong replay needs reproduction evidence. inputs decide a hash;
outputs decide restored files. Request task sandboxing evidence for undeclared
reads or writes, plus the target query and a controlled reproduction. Do not
narrow inputs from task data alone.
Change gate
Recommend a configuration or code edit only after all applicable checks pass:
- Record the matching commit, Nx version, exact target query, and returned fragment.
- Show that its
cache,inputs, oroutputsvalue needs a change. - Before enabling cache, establish a terminating, deterministic task with correct replayable outputs.
- Before removing an input, obtain direct evidence that names it. Prove that its removal cannot affect correct output with a bounded controlled run.
- Explain the correctness risk and get explicit approval before an edit.
Do not recommend an input exclusion from hash differences, a cache-rate trend, or
apparent breadth. If evidence is missing, say No configuration change recommended yet.
Report
# Nx cache investigation
## Scope
- Target and compared run/task/batch IDs: …
- Branch, commit, CI environment, command, API cache state, and missing fields: …
- Workspace Nx version: …, or `Not required for this API-only investigation.`
- Nx target query and returned `cache`, `inputs`, and `outputs`: …, or `Unavailable.`
- Tool-native cache: …, or `Unknown; not inspected.`
- Change gate: `Passed` or `Blocked`; include missing evidence.
## Classification
`No cache failure established` | `Cache artifact retrieval or restoration failure` | `Insufficient task evidence` | `Different computation` | `Same computation, replay not established` | `Suspected unsafe replay`
## Confirmed facts
- …
## Assessment
- **Confirmed** / **Likely** / **Needs diagnostic run:** …
## Next diagnostic step
- Exact query, controlled command, or evidence required.
- Result that confirms or rules out the hypothesis.
## Safe recommendation
- Exact `nx show` result and risk; or `No configuration change recommended yet.`