research(pm): remove retired legacy loop engine

[proerror77]

Change contract

Remove the superseded non-MCTS prediction library loop engine, its engine-only state/ledger/crash-recovery helpers and tests, and the two now-unused filesystem helpers. Preserve the shared proposal/evaluation contracts, mission/snapshot validation, prior helper, and bounded MCTS runner. Rotate the governed prediction policy identity in both BTC/SOL mission templates and align the architecture/task contract with the MCTS fail-closed checkpoint behavior.

Issue relationship

None

Out of scope

Production deployment, collector changes, MCTS behavior changes, live activation, historical evidence deletion, and unrelated prediction-market refactors.

Dependencies and merge order

PR #679 must already be merged. This branch is based on main@a738b5143f1862e7b2ee8182688b8825de063e16.

Focused validation

• Managed worktree preflight: PASS
• cargo fmt -p ploy-research -- --check: PASS
• cargo test -p ploy-research --locked: PASS (341 library tests, 4 binary tests)
• cargo clippy -p ploy-research --locked --all-targets --no-deps -- -D warnings: PASS
• Governed policy identity: sha256:1e3387ac2e5a8d62d516e7700f7037ab76fc69ea3be23b5eb19cccb6c1774559, matched by both BTC/SOL templates
• Retired --legacy-loop: rejected with exit status 2
• Retired library run_or_resume( entry: absent
• Standards review: no findings
• Spec review: no findings

Rollout and rollback

No production or runtime rollout. Live trading remains disabled. Roll back by reverting this PR as one unit.

Scope exception

This deletion exceeds 750 non-generated lines because the user explicitly approved removing the entire retired library loop and the required architecture-contract synchronization. Splitting the engine, its private state/ledger/recovery helpers, engine-only tests, and governed policy pins would leave a half-retired compatibility surface or stale policy identity. Named reviewer approval: user/coordinator authorization in the cleanup task.

Summary by CodeRabbit

• Behavior Changes

  • Interrupted prediction research calls now fail safely when resumed, without replaying or issuing duplicate calls.
  • Research runs now report a streamlined set of pause, budget-exhausted, and failure outcomes.
  • Removed legacy recovery and retry behavior from the superseded research workflow.

• Documentation

  • Updated prediction-market documentation and task guidance to reflect the current bounded research behavior.

• Configuration

  • Updated policy snapshot references for Bitcoin and Solana five-minute market research examples.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e3f69d63-98d8-41d2-bcaa-d4d325f2cf34

📥 Commits

Reviewing files that changed from the base of the PR and between a738b51 and e4f4c65.

📒 Files selected for processing (6)

• docs/architecture/PREDICTION_MARKETS.md
• rust_hft/prediction-markets/config/research_missions/polymarket-btc-5m.example.json
• rust_hft/prediction-markets/config/research_missions/polymarket-sol-5m.example.json
• rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop.rs
• rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop_fs.rs
• rust_hft/prediction-markets/tasks/todo.md

💤 Files with no reviewable changes (1)

• rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop_fs.rs

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📝 Walkthrough

Walkthrough

The PR removes the durable non-MCTS prediction LoopRun engine and related persistence helpers. It retains policy contracts and prior construction, narrows status types, documents fail-closed bounded MCTS checkpoints, and updates two mission policy snapshots.

Changes

Prediction Loop retirement

Layer / File(s)	Summary
Policy contract reduction rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop.rs	The module retains prediction-policy contracts and prior construction. It removes feedback access, Running and Kept statuses, and durable-loop retry ownership.
Durable execution and persistence removal rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop.rs, rust_hft/prediction-markets/crates/ploy-research/src/prediction_loop_fs.rs	The durable execution loop, ledger, checkpoint, recovery, budget reconciliation, terminal evidence, stale-file cleanup, and content-addressed text writing are removed with their implementation-specific tests.
Documentation and mission snapshot alignment docs/architecture/PREDICTION_MARKETS.md, rust_hft/prediction-markets/config/research_missions/*, rust_hft/prediction-markets/tasks/todo.md	Documentation records bounded MCTS checkpoint behavior and fail-closed interruption handling. The BTC and SOL examples use updated policy snapshot identifiers. The task list records retirement of the superseded engine.

Estimated code review effort: 4 (Complex) | ~45 minutes

Possibly related issues

• Cut over prediction research and retire duplicate loop state #189 — Covers retirement of the duplicate prediction LoopRun engine and checkpoint helpers.
• PRD: unify MCTS search control plane across research lanes #184 — Proposes migration from the duplicate LoopRun controller to a shared MCTS kernel.

Possibly related PRs

• proerror77/monday#206 — Updates related prediction checkpoint state in the Formula MCTS flow.
• proerror77/monday#387 — Modifies the prediction research engine and associated policy snapshots.
• proerror77/monday#237 — Overlaps on prediction-loop validation helpers and Polymarket mission snapshot IDs.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies removal of the retired legacy loop engine, which is the primary change in the pull request.
Description check	✅ Passed	The description covers all required sections and clearly states the change, scope, dependencies, validation, rollout, rollback, and scope exception.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/pm-remove-legacy-loop-engine

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