fix(selfhost): validate reporting exporter fast path

[JSONbored]

Motivation

• The incremental fast-path previously used a weak COUNT(*)+MAX(timestamp) fingerprint and trusted any non-empty output DB, which could preserve stale or corrupted reporting snapshots and break observability freshness.
• The change aims to make the skip decision safe by detecting in-place edits that don't change row counts or max timestamps and by ensuring the existing reporting DB is valid before skipping.

Description

• Replace the weak per-table COUNT+MAX fingerprint with a content hash: for SQLite the script sqlite3 "$APP_DB" ".dump <table>" is hashed; for Postgres the script computes an md5 over ordered row_to_json(t) output, and these per-table digests are composed into the source fingerprint in scripts/export-grafana-reporting-db.sh.
• Add reporting_db_ok() which requires sqlite3 "$OUT_DB" "PRAGMA quick_check;" to return ok before the fast-path can skip a rebuild, and include this check in the early-exit condition.
• Harden hash_stdin() to robustly prefer sha256sum then shasum, and fail cleanly when neither exists.
• Add regression tests in test/unit/selfhost-grafana-reporting.test.ts to cover an in-place SQLite edit that keeps count/max unchanged and to ensure a corrupted last-good OUT_DB triggers a rebuild instead of being preserved.

Testing

• Ran git diff --check and it succeeded.
• Ran npx vitest run test/unit/selfhost-grafana-reporting.test.ts and the file's test suite passed (19 tests passed), including the two new regression tests.
• Attempted npm run test:ci but it could not complete due to existing unrelated TypeScript syntax errors in src/queue/processors.ts, so the full CI gate was not run here.
• Attempted npm audit --audit-level=moderate but the registry audit endpoint returned 403 Forbidden, so the audit step could not be completed.

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Codex Task

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.65%. Comparing base (1ec9f94) to head (a507b0c).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4079   +/-   ##
=======================================
  Coverage   93.65%   93.65%           
=======================================
  Files         384      384           
  Lines       35865    35865           
  Branches    13160    13160           
=======================================
  Hits        33589    33589           
  Misses       1618     1618           
  Partials      658      658           

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[superagent-security]

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

[loopover-orb]

Warning

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⏸️ Gittensory review result - manual review recommended

_{Review updated: 2026-07-08 03:21:03 UTC}

2 files · 2 blockers · readiness 93/100 · CI green · clean

⏸️ Suggested Action - Manual Review

• 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.

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.

Signal	Result	Evidence
Code review	❌ 2 blockers	No AI review summary
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: 51 registered-repo PR(s), 43 merged, 505 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	JSONbored; Gittensor profile; 51 PR(s), 505 issue(s).
Gate result	❌ Blocking	Repo-configured hard blocker found.

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: Python, TypeScript, JavaScript, Ruby, Go, Kotlin, MDX, Shell
• Official Gittensor activity: 51 PR(s), 505 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.

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

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