fix(review): add expression index for case-insensitive calibration login lookup

[JSONbored]

Motivation

• The canonicalization change in the calibration read used lower(login) = ? which prevents SQLite/D1 from using the existing (login, created_at) index and makes contributor-triggerable reads scan the entire insert-only ledger, risking availability as the ledger grows.
• A matching expression index preserves the intended case-insensitive lookup semantics while restoring indexed performance for the read path.

Description

• Add a new migration 0146_predicted_gate_calibration_ledger_login_lower_idx.sql that creates an expression index on lower(login), created_at for the predicted_gate_calibration_ledger table to match the WHERE lower(login) = ? lookup.
• Add a regression test in test/unit/predicted-gate-calibration-ledger.test.ts that asserts the index predicted_gate_calibration_ledger_login_lower_idx exists and that EXPLAIN QUERY PLAN for the canonicalized query uses that index rather than scanning the table.
• Refresh generated Worker runtime types (worker-configuration.d.ts) to satisfy the local cf-typegen checks.

Testing

• Ran npx vitest run test/unit/predicted-gate-calibration-ledger.test.ts, and the unit test file passed (25 tests).
• Ran npm run db:migrations:check, which reported migrations are contiguous and the next free number is available (0147).
• Ran git diff --check, which passed with no issues reported for the change set.
• Ran npm run test:ci, which failed during tsc --noEmit on unrelated, pre-existing type errors (missing @jsonbored/gittensory-engine module/types and implicit-any errors in miner tests), so the full CI gate could not be completed locally.
• Ran npm audit --audit-level=moderate, which failed due to the npm registry audit endpoint returning 403 Forbidden (external registry error).

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Codex Task

[superagent-security]

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

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⏸️ Gittensory review result - manual review recommended

_{Review updated: 2026-07-12 21:36:15 UTC}

2 files · 1 AI reviewer · 2 blockers · readiness 93/100 · CI green · clean

⏸️ Suggested Action - Manual Review

Review summary
This PR adds a matching expression index (lower(login), created_at) so the case-insensitive calibration lookup in computeContributorCalibration (predicted-gate-calibration-ledger.ts) can use an index instead of a full table scan, and includes a regression test that verifies both the index's existence and that EXPLAIN QUERY PLAN actually uses it rather than scanning the table. The migration is a plain CREATE INDEX IF NOT EXISTS with no D1-unsupported constructs (no TEMP, PRAGMA, or transaction control), and the test exercises the real read path rather than a fabricated scenario. The PR description references migration '0146' while the actual file is numbered 0147, which is a minor inconsistency but the artifact itself matches the stated 'next free number is 0147' from db:migrations:check.

Nits — 5 non-blocking

• The PR description references migration file '0146_predicted_gate_calibration_ledger_login_lower_idx.sql' but the actual added file is '0147_...'; fix the description for accuracy since the number matters for review traceability.
• Confirm whether the drizzle schema.ts also needs an index declaration mirroring this migration for schema/migration parity, since only the migration file is shown here.
• The 'uses the matching lower(login) expression index...' test at line 240 relies on SQLite's query planner choosing the index for a small in-memory test DB — worth a comment noting this could differ from D1's planner behavior in edge cases, though it's not a blocker.
• Double check the PR description's migration number reference matches the shipped filename (0147) before merge.
• If schema.ts tracks indexes via drizzle, add the corresponding index() declaration there to keep schema and migration in parity.

Concerns raised — review before merging

• No linked issue detected — If this PR is intended to solve an issue, link it explicitly in the PR body.
• Maintainer requires a linked issue — Link the relevant issue (for example Closes #123) before opening the PR.

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Fix the following blocker(s) from this PR review:

1. No linked issue detected — If this PR is intended to solve an issue, link it explicitly in the PR body.

2. Maintainer requires a linked issue — Link the relevant issue (for example `Closes #123`) before opening the PR.

Signal	Result	Evidence
Code review	❌ 2 blockers	1 reviewer
Linked issue	⚠️ Missing	No linked issue or no-issue rationale found.
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 (no linked issue context).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 44 registered-repo PR(s), 36 merged, 435 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	JSONbored; Gittensor profile; 44 PR(s), 435 issue(s).
Gate result	❌ Blocking	Repo-configured hard blocker found.
Improvement	✅ Minor	risk: clean · value: minor — Code changes are accompanied by test evidence.

Review context

• Author: JSONbored
• Role context: owner (maintainer lane)
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: not available
• Official Gittensor activity: 44 PR(s), 435 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Treat this as maintainer-lane context rather than normal contributor-lane activity.
• Explain no-issue PR.
• Link the issue being solved, or explicitly explain why this is a no-issue PR.

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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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.71%. Comparing base (ecb18c1) to head (94c10f5).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

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Flag	Coverage Δ
shard-1	44.02% <ø> (ø)
shard-2	35.22% <ø> (ø)
shard-3	32.01% <ø> (ø)
shard-4	32.08% <ø> (ø)
shard-5	32.73% <ø> (ø)
shard-6	43.47% <ø> (ø)

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