fix(miner): stop doctor's ams-backtest-proposals check from creating and pruning the event ledger

[bitfathers94]

fix(miner): stop doctor's ams-backtest-proposals check from creating and pruning the event ledger

checkAmsBacktestProposals opened the ledger through initEventLedger, which unconditionally
creates the file, runs schema migrations, and retention-prunes rows -- none of which a
read-only diagnostic command should ever trigger. Add openEventLedgerReadOnly, a
driver-enforced read-only connection mirroring checkStoreIntegrity's existsSync +
readOnly:true pattern, and only reach for it when the ledger file already exists; a missing
file now short-circuits straight to the "nothing to propose" detail without touching disk.

Closes #10002

[loopover-orb]

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✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-31 15:08:13 UTC}

3 files · 1 AI reviewer · no blockers · readiness 93/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This PR fixes checkAmsBacktestProposals so it no longer opens the event ledger via initEventLedger (which unconditionally creates/migrates/prunes it), instead short-circuiting on a missing file via existsSync and using a new driver-enforced readOnly:true connection (openEventLedgerReadOnly) when the file exists. The fix correctly targets the root cause (the writer-oriented open path being used from a read-only diagnostic) and mirrors the existing checkStoreIntegrity pattern; tests add both a fresh-laptop no-create check and a regression test proving retention pruning isn't triggered even when an operator has opted into it. The fail-open catch-all is preserved and the new read-only-table-missing case correctly closes the connection before rethrowing.

Nits — 5 non-blocking

• packages/loopover-miner/lib/event-ledger.ts: the `readOnly` vs `readonly` camelCase footgone is documented only in a comment; consider a small assertion or type-level guard so a future refactor can't silently reintroduce the lowercase typo.
• test/unit/miner-status.test.ts: the two miner(doctor): checkAmsBacktestProposals creates and retention-prunes the event ledger from a read-only command #10002 tests (`doctor does not create the event ledger...` and the `REGRESSION:` one) overlap significantly in intent — worth consolidating or clearly differentiating their purpose in comments.
• packages/loopover-miner/lib/status.ts:checkAmsBacktestProposals now has three exit paths (missing-file, success, catch) — consider a short comment noting that `existsSync` + readOnly open together close the TOCTOU window's only real consequence (throw, caught below), not a race that needs locking.
• Consider extracting the `existsSync(dbPath)` + `openEventLedgerReadOnly` pattern into a small shared helper if a third read-only-only doctor check appears, to avoid re-deriving the same three-branch shape.
• The JSDoc on `openEventLedgerReadOnly` is thorough; a one-line summary above the detailed block would make it skimmable for future readers.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#10002
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	⚠️ 20/25	Preflight is ready, but the PR body does not name the validation run.
Contributor workload	✅ 10/10	Author activity: 140 registered-repo PR(s), 99 merged, 3 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	bitfathers94; Gittensor profile; 140 PR(s), 3 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: moderate

Linked issue satisfaction

Addressed
The PR adds openEventLedgerReadOnly using the driver-enforced readOnly:true DatabaseSync form, and rewrites checkAmsBacktestProposals to short-circuit on existsSync(dbPath) before ever opening a handle, avoiding initEventLedger's create/migrate/prune path entirely while preserving the byte-identical detail strings and fail-open catch behavior. It leaves initEventLedger, pruneLedgerByRetention, and

Review context

• Author: bitfathers94
• 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: 140 PR(s), 3 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Add validation command/output.

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.

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

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[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 80.69%. Comparing base (0bc00ab) to head (711138a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10264      +/-   ##
==========================================
+ Coverage   80.60%   80.69%   +0.08%     
==========================================
  Files         283      285       +2     
  Lines       59101    59372     +271     
  Branches     7000     7086      +86     
==========================================
+ Hits        47641    47910     +269     
  Misses      11167    11167              
- Partials      293      295       +2     

Flag	Coverage Δ
backend	99.26% <100.00%> (?)

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

Files with missing lines	Coverage Δ
packages/loopover-miner/lib/event-ledger.ts	100.00% <100.00%> (ø)
packages/loopover-miner/lib/status.ts	98.85% <100.00%> (ø)

[loopover-orb]

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