Expose corpus job artifact surfaces

[chubes4]

Summary

• Adds generic corpus indexing job summary conventions so job list/detail and job artifact payloads can expose concise operator-facing counts and artifact references.
• Preserves corpus artifact metadata through job artifact projection without narrowing Data Machine to a product-specific corpus implementation.
• Adds a separate corpus artifact retention policy hook, CLI/system-task retention surface, and scoped artifact-file cleanup path.

Closes #2490.

Tests

• php tests/corpus-job-surfaces-smoke.php
• php tests/retention-system-tasks-smoke.php
• vendor/bin/phpcs inc/Abilities/Job/JobHelpers.php inc/Core/CorpusJobSurfaces.php inc/Core/JobArtifacts.php inc/Core/FilesRepository/FileCleanup.php inc/Engine/AI/System/Tasks/Retention/RetentionCleanup.php inc/Engine/AI/System/SystemAgentServiceProvider.php inc/Engine/AI/System/Tasks/Retention/RetentionCorpusArtifactsTask.php inc/Cli/Commands/RetentionCommand.php tests/corpus-job-surfaces-smoke.php tests/retention-system-tasks-smoke.php
• git diff --check

Remaining risks

• The new artifact retention cleanup targets JSON files under the existing Data Machine job artifact directory and relies on artifact payload retention_scope or known generic corpus artifact types; consumers still need to write artifact payloads using those conventions.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (gpt-5.5)
• Used for: Drafted and verified the generic job summary, artifact projection, retention hooks, and smoke test changes for Chris to review.

[homeboy-ci]

Homeboy Results — data-machine

Lint

❌ lint — failed

ℹ️ Auto-fix: homeboy lint data-machine --path /home/runner/work/data-machine/data-machine --changed-since 6745e42 --fix (or homeboy refactor data-machine --path /home/runner/work/data-machine/data-machine --changed-since 6745e42 --from lint --write)
ℹ️ Some issues may require manual fixes
ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-lint-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-lint-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920262337

Test

✅ test — passed

• 445 passed
• 3 skipped

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Save test baseline: homeboy test data-machine --baseline
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-test-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-test-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920262337

Audit

✅ audit — passed

• audit — 48 finding(s)
• Total: 48 finding(s)

Deep dive: homeboy audit data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-audit-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920262337

Tooling versions

• Homeboy CLI: homeboy 0.220.1+9c0e56c0
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 1f9ab9d7
• Action: unknown@unknown

[chubes4]

Lint follow-up from controller triage: Homeboy observations show 37 PHPCS findings, primarily formatting/alignment in inc/Core/CorpusJobSurfaces.php; examples include assignment alignment at lines 14 and 17 and array double-arrow alignment around lines 64-66. Homeboy autofix failed because its runner saw uncommitted changes, so please fix manually or with a clean local fixer run, rerun lint/test, and push.