Consume results programmatically

Scope: everything downstream of a passing gate, meaning structured output, run history, and regression detection. Installing the gate is Add moose-tracevals to CI; the field-by-field structure is in the reference.

The gate answers did it pass? This page is about answering is it getting worse?

Emit machine-readable output

npx moose-tracevals run <trace> --deterministic-only --format json

--output additionally writes the rendered report to a file, in whichever format --format selected. Both together give you one artifact to keep and one stream to pipe:

npx moose-tracevals run <trace> --deterministic-only \
  --format json --output moose-tracevals-report.json

JSON goes to stdout with everything else

--format json writes the report to stdout. If you are piping it, keep other output off that stream. Use --output and read the file when a step also prints diagnostics.

Query it

The report is one object, so jq gets you most things in a line. Every field is documented in Reports & exit codes.

Which evals failed, and why:

jq -r '.evalResults[]
       | select(.outcome == "fail")
       | "\(.artifactName) › \(.evalName): \((.findings // [])[].message)"' \
  moose-tracevals-report.json

Anything a human needs to look at:

jq -r '.evalResults[] | select(.outcome == "needs-review") | .evalName' moose-tracevals-report.json

Artifacts the session referenced but could not be found:

jq -r '.coverage[] | select(.resolved == false) | "\(.kind) \(.ref)"' moose-tracevals-report.json

Summary counts for a dashboard:

jq '.summary' moose-tracevals-report.json

{ "total": 7, "pass": 1, "fail": 1, "error": 0, "needsReview": 0, "skipped": 5 }

Prefer the JSON report over parsing the rendered one

The human format is colored, wrapped, and tuned for a terminal; the markdown format is tuned for a PR comment. Neither is a contract. --format json is.

Query a batch

Evaluating more than one trace emits a different object. It is a BatchReport whose evals and artifacts arrays carry rates instead of outcomes. The summary counts are the same fields, summed, plus four per-trace tallies.

npx moose-tracevals run traces/*.jsonl --deterministic-only \
  --format json --output moose-tracevals-batch.json

The evals that hold least often, worst first. This is the one query that makes a corpus worth keeping:

jq -r '.evals
       | map(select(.passRate != null))
       | sort_by(.passRate)[]
       | "\(.passRate * 100 | floor)%  \(.artifactName) › \(.evalName)  (\(.traces) trace(s))"' \
  moose-tracevals-batch.json

The traces to open first, for one eval that is failing:

jq -r '.evals[] | select(.evalName == "forbidden-tool") | .failingTraces[]' \
  moose-tracevals-batch.json

Traces that could not be read at all. These do not appear in any rate, so they are easy to miss:

jq -r '.traces[] | select(.error) | "\(.file): \(.error)"' moose-tracevals-batch.json

Anything that was never actually checked, with the reason. An exhausted judge budget shows up here, and it is the difference between “this held every time” and “this was never run”:

jq -r '.evals[] | select(.passRate == null)
       | "\(.artifactName) › \(.evalName): \(.skipReasons | join("; "))"' \
  moose-tracevals-batch.json

`passRate` is null, not zero, when nothing was graded

Skipped evals are excluded from the denominator, so an artifact the sessions never invoked reports null rather than 100% or 0%. Filter on select(.passRate != null) before sorting or averaging, or a never-checked eval will quietly rank as your worst, or your best.

Track runs over time

--history appends one line per run to a local JSONL log and compares this run against the previous one for the same session:

npx moose-tracevals run <trace> --deterministic-only --history

The file defaults to .moose-tracevals/history.jsonl and is configurable:

moose.config.yaml

tracevals:
  history:
    file: .moose-tracevals/history.jsonl

Each line is a HistoryEntry. It carries timestamp, trace file, session id, project, the summary counts, exit code, judge cost, and one { artifact, evalName, outcome } per eval. Outcomes only; findings and consensus are not stored, which keeps the log small enough to commit if you want to.

History is local, and matched per session

The comparison looks for the most recent earlier entry with the same sessionId, falling back to the trace path. On an ephemeral CI runner the file starts empty every time, so there is nothing to compare against. To get trend data out of CI you have to persist the file yourself. Cache it, commit it, or ship each run’s JSON somewhere central and diff there.

Detect a regression

A regression is a specific, defined event: an eval that was pass in the previous run and is now fail or error. That precision is what makes an alert worth wiring up.

With --history, the comparison is appended to non-JSON output:

History vs 2026-07-01T09:14:22.104Z:
  regression: fix-bug › used-read
  added: fix-bug › reproduces-before-fixing

Line	Meaning
regression	previously pass, now fail or error
improvement	previously fail or error, now pass
added	an eval that did not exist in the previous run
removed	an eval that existed then and does not now
no changes	the outcome set is identical

added and removed matter more than they look. They are how you notice that an eval was quietly deleted, or that an artifact stopped being referenced at all.

Comparing two runs yourself

If you keep the JSON rather than the history file, the same rule is a few lines:

jq -n --slurpfile before before.json --slurpfile after after.json '
  ($before[0].evalResults | map({key: "\(.artifact)›\(.evalName)", value: .outcome}) | from_entries) as $b
  | $after[0].evalResults
  | map(select($b["\(.artifact)›\(.evalName)"] == "pass"
               and (.outcome == "fail" or .outcome == "error")))
  | map("\(.artifactName) › \(.evalName)")'

Publish a summary

For a human-readable artifact next to the machine-readable one, run the markdown reporter:

      - name: Evaluate and keep both formats
        run: |
          npx moose-tracevals run traces/session.jsonl --deterministic-only \
            --format markdown --output moose-tracevals-report.md
          npx moose-tracevals run traces/session.jsonl --deterministic-only \
            --format json --output moose-tracevals-report.json

      - name: Publish
        if: always()
        uses: actions/upload-artifact@v5
        with:
          name: moose-tracevals-report
          path: moose-tracevals-report.*

The second run is free. Judged verdicts are cached, and under --deterministic-only there is no model call at all.

Or skip the CLI

Are you building something that runs evaluations rather than reading their output? The library gives you the typed report directly, plus seams for keeping your own suite offline.

Where to go next

Every report fieldThe full RunReport, EvalResult, consensus, and CoverageEntry shapes, and the history file format.

Build on the libraryThe export map, the injection seams, and how to register a grader the built-ins do not cover.