feat(discovery-index): replace Sentry with PostHog for error tracking + sourcemap pipeline

[JSONbored]

Summary

Per the epic's revised strategy (correction comment on #8286, 2026-07-25): PostHog replaces Sentry directly, not a parallel-run sink. This PR's history reflects that: the first commit added PostHog alongside the existing Sentry wiring; the second commit finishes the swap by removing Sentry entirely.

• Deleted: src/sentry.ts, scripts/validate-sentry-release.mjs, @sentry/node, @sentry/cli, and the live metagraphed Sentry DSN that was baked into wrangler.jsonc's vars -- a genuine cross-project entanglement (discovery-index reporting into a different product's shared Sentry project), exactly the problem this migration set out to fix.
• Added: src/posthog.ts (mirrors the deleted sentry.ts's shape 1:1) and scripts/validate-posthog-release.mjs (narrower than the deleted Sentry validator, since PostHog's release model has no commits/deploys/finalize lifecycle -- just symbol-set presence + no failure_reason via error_tracking/symbol_sets).
• upload-sourcemaps.ts's PostHog inject/upload/validate flow is now the only path (no more Sentry-then-PostHog sequencing or exit-code combining).
• @posthog/cli is pinned to an exact version (0.9.1, no caret) -- its postinstall script downloads a platform binary over HTTPS with no checksum verification.
• Rebased onto current main to pick up fix(deps): resolve postcss + tar audit findings via overrides #8612's postcss/tar dependency-audit fix, which an earlier npm install --workspace in this branch had inadvertently regressed to pre-fix versions.

All PostHog config is wired end-to-end but not yet a real wrangler.jsonc var/secret -- #7875 (a real loopover-owned PostHog project) isn't finished, so every path stays a complete no-op until then.

Closes #8289

Test plan

• npm run typecheck (repo root + discovery-index package + cf:typecheck) clean
• npx vitest run test/unit/discovery-index/ -- 180/180 passing, 100% line/branch coverage on every touched file
• npm run build --workspace @loopover/discovery-index and cf:typecheck clean
• npm audit --audit-level=moderate -- only the pre-existing, already-tracked eslint/brace-expansion finding (Bump eslint to v10 to resolve brace-expansion/minimatch DoS chain (GHSA-mh99-v99m-4gvg) #8608-8610), nothing new

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	loopover-ui	2bfc6af	Commit Preview URL Branch Preview URL	Jul 25 2026, 08:45 AM

[superagent-security]

Superagent found 1 security concern(s).

[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.57%. Comparing base (a972353) to head (6561117).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8614      +/-   ##
==========================================
+ Coverage   92.55%   92.57%   +0.01%     
==========================================
  Files         798      799       +1     
  Lines       79850    79976     +126     
  Branches    24120    24156      +36     
==========================================
+ Hits        73908    74034     +126     
  Misses       4803     4803              
  Partials     1139     1139              

Flag	Coverage Δ
backend	93.75% <100.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
packages/discovery-index/src/app.ts	100.00% <100.00%> (ø)
packages/discovery-index/src/posthog.ts	100.00% <100.00%> (ø)
packages/discovery-index/src/upload-sourcemaps.ts	100.00% <100.00%> (ø)

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-25 08:33:02 UTC}

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

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This PR adds a parallel PostHog error-tracking + sourcemap pipeline to discovery-index that mirrors the existing sentry.ts/upload-sourcemaps.ts shape closely, wiring in app.ts/server.ts/worker.ts/wrangler.jsonc/Dockerfile, with extensive matching test coverage. The implementation is internally consistent, correctly no-ops everywhere when config is unset (verified by tracing initDiscoveryIndexPostHog, runPostHogSourcemapUpload's missing-config check, and the captureScopedError active/client guards), and the PR body itself flags the pending #7875 dependency and gated #8298 decommission for the eventual Sentry removal. The description states linked issue #8289 with full coverage per the review brief. The Superagent Security Scan failure has no detail provided and this branch is 2 commits behind default, so per grounding rules I cannot attribute that failure to a specific defect in this diff.

Nits — 7 non-blocking

• `packages/discovery-index/src/posthog.ts:27` and `scripts/validate-posthog-release.mjs:10` hardcode the PostHog US-cloud host as a literal rather than a shared constant, though this matches the existing sentry.ts pattern in this repo so it's consistent, not a regression.
• `packages/discovery-index/src/upload-sourcemaps.ts:244-278` repeats several magic numbers (5, 20, 30_000, 500ms slicing) already present in the Sentry leg's `runReleaseValidation`/`numericEnv` — copied duplication rather than a shared helper, per the file's own stated 'literal copy, no compile-time dependency' design choice.
• `@​posthog/cli@​0.9.1` runs a postinstall script — worth a quick manual check of what it does before merging, since install-time scripts are a supply-chain vector even for a well-known vendor CLI.
• The flagged 'potential leaked secrets' at `posthog.test.ts:254` and `upload-sourcemaps.test.ts:83` are test fixture placeholder strings (`phc_test`, `phx_test_personal_key`), not real credentials — safe, but worth a quick confirm they're not accidentally real.
• Consider factoring the retry-loop constants (max attempts 20, default delay 30_000ms) shared between Sentry's and PostHog's `numericEnv`/validation-retry logic into one small shared helper module now that there are two near-identical implementations, to avoid a third copy showing up in a future sink.
• PR author also opened the linked issue — Link an issue that was opened by a different contributor, or provide a rationale for why this self-authored issue represents genuine discovery work.
• Possible secret-shaped assignment in the diff (generic_secret_assignment) — Verify the value is not a real credential.

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	#8289
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: 13 registered-repo PR(s), 13 merged, 250 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	JSONbored; Gittensor profile; 13 PR(s), 250 issue(s).
Improvement	✅ Minor	risk: clean · value: minor

Linked issue satisfaction

Addressed
The PR adds src/posthog.ts mirroring sentry.ts's redaction/fingerprint/tag-allowlist shape, wires it in parallel at all three capture sites, replaces the sourcemap pipeline with a posthog-cli leg plus a new validate-posthog-release.mjs validator, wires the loopover project key vars (pending #7875 provisioning, tracked transparently), keeps the Sentry path fully intact, and adds a substantial parit

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, Ruby, Go, MDX, Shell, Solidity, JavaScript
• Official Gittensor activity: 13 PR(s), 250 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Treat this as maintainer-lane context rather than normal contributor-lane activity.

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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