Store workflow output

[erlenlh]

Issue
Resolves #13320

Approach
Second of two PRs splitting the original "Store workflow output" work. The base
PR (#14301) captures workflow job
output and writes it to the ERT log; this one makes that output available to the
GUI and ties it to the experiment it belongs to.

• Adds WorkflowEvent, carrying the output of a single job invocation so it can
  travel over the status queue like the other run model events. It is a plain
  BaseModel rather than a RunModelEvent because PRE_EXPERIMENT hooks run
  before an ensemble exists, so the mandatory iteration and run_id of
  RunModelEvent are not always available.
• Persists the events alongside the experiment, one JSON object per line in
  workflow_events.jsonl. Appending keeps every hook of a run in one file, in
  the order they ran.
• Emits an event per job invocation from run_workflows. Workflows skipped
  because the user cancelled are reported as cancelled rather than dropped, so
  the run is not misrepresented as having completed.

Events are held back until an experiment exists, since PRE_EXPERIMENT hooks run
before storage is created, and are flushed in a finally block so output
survives a workflow that stops the experiment. Failing to persist is logged but
does not abort the experiment.

Events are consumed by the GUI in the follow-up PRs in this stack.

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When screenshots are changed: Review screenshot-PR in ert-testdata,
  merge screenshot-PR in ert-testdata before merging this PR.
• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Add backport label to latest release (format: 'backport release-branch-name')

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.79%. Comparing base (5682c06) to head (dedec36).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@                   Coverage Diff                   @@
##           log-workflow-output   #14062      +/-   ##
=======================================================
+ Coverage                91.77%   91.79%   +0.01%     
=======================================================
  Files                      486      486              
  Lines                    34849    34902      +53     
=======================================================
+ Hits                     31983    32038      +55     
+ Misses                    2866     2864       -2     

Flag	Coverage Δ
cli-tests	35.98% <84.61%> (+0.08%)	⬆️
fuzz	43.88% <56.92%> (+0.03%)	⬆️
gui-tests	58.30% <84.61%> (+0.04%)	⬆️
performance-and-unit-tests	81.07% <100.00%> (+0.04%)	⬆️
test	45.49% <81.53%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/ert/run_models/event.py	99.00% <100.00%> (+0.17%)	⬆️
src/ert/run_models/run_model.py	93.39% <100.00%> (+0.89%)	⬆️
src/ert/storage/local_experiment.py	96.42% <100.00%> (+0.07%)	⬆️

[Copilot]

Pull request overview

This PR adds structured capture and persistence of workflow-job output (stdout/stderr) so that workflows hooked into experiment runs can be logged to <UPDATE_LOG_PATH>/<run_id>/workflows.log and appended to the experiment’s storage directory workflows.log. It introduces a dedicated status event for workflow output, and wires both CLI and GUI monitors to write these logs.

Changes:

• Capture stdout/stderr for internal and external workflow jobs (including failure cases) and surface per-invocation results.
• Introduce RunModelWorkflowLogEvent with a stable log-entry format, write it to update-log output paths, and append it to experiment storage.
• Add unit/UI tests and docs describing the new workflow logging behavior.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/ert/config/ert_script.py	Adds thread-aware stdout/stderr capture proxy, plus ExternalScriptError handling to avoid ERT-internal stack traces for external job exit failures.
src/ert/config/external_ert_script.py	Writes subprocess stdout/stderr to current streams (so ErtScript capture can record it) and raises ExternalScriptError with an exit-code message.
src/ert/workflow_runner.py	Adds WorkflowJobResult and WorkflowRunner.jobResults() to preserve per-invocation output (including repeated job runs).
src/ert/run_models/event.py	Introduces RunModelWorkflowLogEvent with as_log_entry() and write_as_log() for update-log persistence.
src/ert/run_models/run_model.py	Emits workflow log events per job, buffers log entries until an experiment exists, and appends them to experiment storage.
src/ert/storage/local_experiment.py	Adds workflow_log_path and append_workflow_log() to persist workflow log entries alongside the experiment.
src/ert/cli/monitor.py	Writes workflow log events to <UPDATE_LOG_PATH>/<run_id>/workflows.log during CLI runs.
src/ert/gui/experiments/run_dialog.py	Writes workflow log events to the GUI output path.
tests/ert/unit_tests/workflow_runner/test_workflow_runner.py	Adds coverage for external-job stdout capture, exit-code error reporting, and per-invocation job results.
tests/ert/unit_tests/workflow_runner/test_ert_script.py	Adds coverage for stdout/stderr capture, failure behavior, and concurrent/threaded capture isolation.
tests/ert/unit_tests/run_models/test_workflow_log_event.py	New tests for RunModelWorkflowLogEvent log formatting and file append semantics.
tests/ert/unit_tests/run_models/test_status_events_serialization.py	Extends status-event serialization coverage to include RunModelWorkflowLogEvent.
tests/ert/unit_tests/run_models/test_base_run_model.py	Adds tests asserting workflow log event emission and storage persistence behavior across hooks/iterations.
tests/ert/unit_tests/gui/experiments/test_run_dialog.py	Adds GUI test to verify workflow log events are written to the output path.
tests/ert/ui_tests/cli/test_cli.py	Adds CLI UI test ensuring workflow output is written into the update log path.
docs/ert/reference/workflows/complete_workflows.rst	Documents that hooked workflow output is also written to update-log and experiment storage logs.
docs/ert/reference/configuration/keywords.rst	Documents the workflow log location/format under UPDATE_LOG_PATH, including storage-copy behavior and hook scope.

Suppressed comments (1)

tests/ert/unit_tests/workflow_runner/test_ert_script.py:183

• Thread exceptions can be missed, and the join loop doesn’t assert that worker threads actually finished. Add an is_alive() assertion after each join so this test fails deterministically instead of leaking threads on failure paths.

    for thread in threads:
        thread.start()
    for thread in threads:
        thread.join(timeout=10)

[codspeed-hq]

Merging this PR will not alter performance

✅ 36 untouched benchmarks

---

_{Comparing store-workflow-output (a5b9131) with main (21e9203)¹}

Footnotes

1. No successful run was found on log-workflow-output (002c15e) during the generation of this report, so main (21e9203) was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated no new comments.

Suppressed comments (3)

src/ert/config/ert_script.py:63

• The linked issue requires workflow stdout/stderr to be rerouted away from the user's terminal, but this forwarding path deliberately writes every captured byte back to the original stream. As a result, internal and external workflow output still appears in the terminal in addition to the log, so #13320's requested behavior is not implemented. Suppress forwarding for a thread with an active capture while continuing to forward writes from unrelated threads, and update the passthrough test accordingly.

        if self.wrapped is None:
            return len(s)
        return self.wrapped.write(s)

src/ert/run_models/run_model.py:947

• This clears all pending events even when append_workflow_events() raises. A transient storage error therefore permanently drops buffered PRE_EXPERIMENT and current-hook output, and later hooks cannot retry it. Clear only events known to have been committed; because the append can partially succeed, this needs an atomic append or a commit result rather than simply retaining or clearing the whole batch.

        except Exception:
            logger.exception("Failed to persist workflow events to storage")
        self._pending_workflow_events = []

docs/ert/reference/workflows/complete_workflows.rst:116

• This documents a GUI tab that this PR does not add: there is no workflow-event reader or “Workflow events” tab under src/ert/gui, and the PR description explicitly defers frontend consumption to a later PR. Users following these instructions cannot view the stored output as described; document the file as reserved for the future GUI instead.

in the GUI, select the experiment in the *Experiments* tool, then select the
*Workflow events* tab.

The GUI will show a list of all workflow jobs that have
been run for that experiment, and clicking on a job will show its output.