refactor(engine): extract signals engine with re-export shim (#4884)

[andriypolanski]

Summary

• Completes the Extract the signals-engine file #4884 deliverable from the ORB Cloud Readiness engine-extraction milestone: move src/signals/engine.ts (largest, highest-fan-in file in the candidate set) into @loopover/engine.
• Leaves a temporary full re-export shim at the old path so none of the many consumers need an import-path change in this PR.
• No behavior change — move + shim + parity-tooling path update only; follows the established playbook from Verify git mv rename recognition in coverage/diff tooling #4878 / Extract content-lane/* as one vertical slice #4880 / Extract the rest of signals/ #4883.

Change

• packages/loopover-engine/src/signals/engine.ts — canonical home for the maintainer signal stack (collision detection, queue health, lane advice, preflight, bounty context, etc.).
• src/signals/engine.ts — thin export * shim over the engine source path (same convention as src/signals/check-summary.ts / Extract the rest of signals/ #4883).
• src/signals/reward-risk.ts — binds RewardRiskEngineDeps against the engine package builders directly, avoiding a shim circular import after the move.
• packages/loopover-engine/tsconfig.json — excludes src/signals/engine.ts from the published package tsc build (still host-bound via monorepo-relative imports; consumed through the shim, not dist/).
• scripts/check-engine-parity.ts + test/unit/check-engine-parity-script.test.ts — update SHARES_MEANINGFUL_FILE_TWIN_PAIR host path to the engine package location.
• Comment updates in packages/loopover-engine/src/reward-risk.ts and packages/loopover-engine/src/signals/slop.ts to point at the new canonical path.

Acceptance

Criterion	Status
Every known external consumer keeps working with zero import-path changes	Yes — shim at src/signals/engine.ts
Full existing test coverage for this file passes unchanged	Yes — signals / reward-risk / parity suites green
No other refactor / cleanup / behavior change in the same PR	Yes — move-only + shim wiring

Closes #4884

---

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• This PR is focused (signals-engine extraction only) and does not mix unrelated changes.
• This follows CONTRIBUTING.md and does not touch site/, CNAME, or **/lovable/**.
• Linked issue: Closes Extract the signals-engine file #4884.

Validation

• git diff --check
• npm run test:ci
• npm audit --audit-level=moderate
• npm run typecheck
• npm run build --workspace @loopover/engine
• npm run test:engine-parity
• npm run test -- test/unit/signals.test.ts test/unit/signals-v2.test.ts test/unit/signals-coverage.test.ts test/unit/check-engine-parity-script.test.ts — 189 passing
• Consumer smoke: local-branch, contributor-issue-draft, feasibility-gate-branches, maintainer-slop-duplicate-trend, scenario-summary, reward-risk-freshness — 150 passing

If any required check was skipped, explain why:

• Run the full npm run test:ci + npm audit --audit-level=moderate gate locally before push (required for merge).

Safety

• No secrets, wallet details, hotkeys, coldkeys, PATs, private keys, trust scores, or private rankings exposed.
• Public GitHub text unaffected — refactor/move only; no runtime API or comment-template change.
• Auth/cookie/CORS/session — n/a.
• API/OpenAPI/MCP — n/a (engine not re-exported from the published barrel in this PR).
• No visible UI change.
• No changelog edit.

UI Evidence

No visible UI change. This PR moves the signals engine behind a re-export shim. No screenshots required.

Notes

• The moved file still imports some host-only modules (src/types, src/db/repositories, src/review/*, etc.) via monorepo-relative paths; it is excluded from the engine package tsc build so @loopover/engine's published dist/ stays free of those host edges. A later extraction can cut those remaining host imports.
• Follows Strategy A from Verify git mv rename recognition in coverage/diff tooling #4878 (coverage-safe-file-moves.md): preserve consumer import paths via shim; do not combine with other refactors in this PR.
• Prior slices in this milestone: Extract content-lane/* as one vertical slice #4880 (content-lane leaves), Extract the rest of signals/ #4883 (unlinked-issue candidates), Finish the settings/ slice extraction #4879 (settings leaves).

[loopover-orb]

Tip

🟩🟩🟩🟩🟩🟩🟩🟩🟩🟩🟩🟩

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-14 18:10:17 UTC}

8 files · 1 AI reviewer · no blockers · readiness 100/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
The AI review returned non-blocking notes for this change but did not include a separate narrative summary. Review the nits below before deciding this PR.

Nits — 3 non-blocking

• The added `packages/loopover-engine/src/signals/engine.ts` (+5807 lines) has no inline diff shown, so its contents can't be directly verified here beyond trusting it's a byte-for-byte move — worth a spot-check that it's truly identical to the old `src/signals/engine.ts` content rather than a re-implementation.
• Confirm via `git diff --stat` or a hash comparison that the moved `engine.ts` content is unchanged beyond the file move, since the diff view can't show a byte-identical move for a 5807-line addition/deletion pair.
• Code changes lack test evidence — Add focused regression tests or explain why existing coverage is sufficient.

Signal	Result	Evidence
Code review	✅ No blockers	1 reviewer
Linked issue	✅ Linked	#4884
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 151 registered-repo PR(s), 98 merged, 26 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	andriypolanski; Gittensor profile; 151 PR(s), 26 issue(s).
Gate result	✅ Passing	No configured blocker found.
Improvement	⚠️ ℹ️ None detected	risk: low · value: none — No structural-improvement signals were detected for this PR. LLM value judgment: moderate — The PR completes a well-scoped, single-purpose file move (largest file in the extraction milestone) with a compatibility shim and updated tooling references, directly closing the linked issue #4884 with no bundled unrelated changes visible in the diff.

Review context

• Author: andriypolanski
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: not available
• Official Gittensor activity: 151 PR(s), 26 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Keep the PR focused and include validation evidence before maintainer review.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

[BETA] Chat with Gittensory

Ask Gittensory a question about this PR directly in a comment — grounded only in the same cached, public-safe facts shown above, never a new claim.

• @gittensory ask <question> answers contribution-quality Q&A with source citations and freshness.
• @gittensory chat <question> answers in natural prose from cached decision-pack facts via local inference (maintainer/collaborator; read-only).
• A plain-language @gittensory mention with a real question is routed to the closest matching read-only command automatically -- no exact syntax required.

Full command reference: https://gittensory.aethereal.dev/docs/gittensory-commands

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

---

💰 Earn for open-source contributions like this. Gittensor lets GitHub contributors earn for the work they already do — register to start earning →.

Checked by LoopOver, a quiet PR intelligence layer for OSS maintainers.

• Re-run LoopOver review

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.10%. Comparing base (9b3f4b2) to head (162a1cb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5800   +/-   ##
=======================================
  Coverage   95.10%   95.10%           
=======================================
  Files         584      584           
  Lines       46440    46440           
  Branches    14849    14849           
=======================================
  Hits        44169    44169           
  Misses       1515     1515           
  Partials      756      756           

Flag	Coverage Δ
shard-1	43.76% <ø> (+<0.01%)	⬆️
shard-2	36.20% <ø> (+<0.01%)	⬆️
shard-3	32.15% <ø> (ø)
shard-4	32.92% <ø> (+<0.01%)	⬆️
shard-5	31.63% <ø> (+<0.01%)	⬆️
shard-6	44.53% <ø> (+<0.01%)	⬆️

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

Files with missing lines	Coverage Δ
packages/loopover-engine/src/reward-risk.ts	100.00% <ø> (ø)
packages/loopover-engine/src/signals/engine.ts	97.50% <ø> (ø)
packages/loopover-engine/src/signals/slop.ts	100.00% <ø> (ø)
src/signals/reward-risk.ts	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[loopover-orb]

Gittensory approves — the gate is satisfied and CI is green.