test(github): verify installation-token isolation under multi-tenant concurrency

[JSONbored]

Summary

Rent-a-Loop's #4794 ("Scoped credential handling") asked for verified, documented behavior that one tenant's credentials can never be used against another tenant's repo. Read the existing installation-token cache/mint layer (src/github/app.ts) end to end before writing anything:

• installationTokenCache (in-isolate Map) and the external InstallationTokenStore interface (Redis, self-host fleet) are both keyed correctly by installationId throughout.
• inFlightMints (the single-flight coalescing map for cold-cache concurrent mints) is also keyed by installationId — no shared key collision risk.
• Every queue-processor call site (src/queue/processors.ts) threads installationId as a local variable or job-payload field, never through module-level/shared mutable state (grepped every non-cache let/var at module scope across src/github/*.ts, src/queue/*.ts, src/review/*.ts — the only two found were an unrelated store-reference pointer and a process-wide REES-auth flag, neither tenant-scoped).

No code changes were needed — the mechanism was already sound. Added the adversarial tests that actually prove it, since none of the existing token tests exercised more than one installation concurrently:

• Two tenants racing on a cold in-isolate cache each single-flight to exactly one mint of their own installation, zero cross-contamination, warm-cache re-reads confirmed isolated too.
• Same proof against the external (Redis self-host fleet) token store, since that's the shared-across-replicas path where a real key-collision bug would matter most.

Also fixes a stale addBlockedBy mutation field name in the contributor-gardening skill's reference doc (blockedById → blockingIssueId), caught while wiring #5669's relationship graph in an earlier session pass — never committed until now.

Closes #4794 — this PR is exactly its "Verified, documented behavior (with tests)" deliverable.

Test plan

• npx tsc --noEmit clean
• npm run test:coverage (unsharded): 894 files / 17152 tests passed, 0 failures
• npm audit --audit-level=moderate: 0 vulnerabilities
• npm run test:ci (full local gate incl. drift checks, engine parity, MCP/miner packs, UI build): green, verified via literal captured exit code, not a piped one
• Rebased onto latest origin/main (picked up the concurrent fumadocs-mdx docs migration cleanly, npm ci + fumadocs-mdx source.config.ts codegen re-run), no conflicts

[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 95.35%. Comparing base (f8aec19) to head (8abc893).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6277   +/-   ##
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  Coverage   95.35%   95.35%           
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  Files         598      598           
  Lines       47127    47127           
  Branches    14994    14994           
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  Hits        44940    44940           
  Misses       1463     1463           
  Partials      724      724           

Flag	Coverage Δ
shard-1	43.97% <ø> (-0.08%)	⬇️
shard-2	36.78% <ø> (+0.19%)	⬆️
shard-3	32.35% <ø> (+0.01%)	⬆️
shard-4	33.76% <ø> (-0.61%)	⬇️
shard-5	31.61% <ø> (-0.19%)	⬇️
shard-6	45.21% <ø> (+0.30%)	⬆️

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[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-16 00:27:55 UTC}

2 files · 1 AI reviewer · no blockers · readiness 82/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This is a pure test-addition PR that adds two adversarial concurrency tests proving the existing installationId-keyed cache/mint layer never cross-contaminates two tenants' tokens, both for the in-isolate cache and the external Redis-backed store, plus a one-line doc fix for a stale GraphQL field name. The tests exercise a genuine concurrent race (Promise.all across two tenants with 5 interleaved callers each) against a fetch mock keyed by installationId, and the assertions (single mint per tenant, no cross-tenant token strings, warm-cache re-reads) actually validate the isolation claim rather than fabricating an unreachable scenario. No production code is touched, matching the PR's claim that no fix was needed — this is documentation-via-tests for #4794.

Nits — 5 non-blocking

• The second test (test/unit/github-app.test.ts) doesn't assert on mint counts to confirm single-flight coalescing under concurrency the way the first test does — consider adding a mintsByInstallation-style counter there too for symmetry.
• The inline comments in the new test blocks are fairly long for the stated no-comments convention seen elsewhere in the file; consider trimming to the non-obvious parts only.
• Consider adding a negative-path assertion that TENANT_A's token never equals any TENANT_B token value (not just prefix-based), to guard against a future format change silently breaking the prefix check.
• Since this PR closes Scoped credential handling #4794, link the issue number directly in the test description strings is already done well — keep this pattern for future adversarial-proof PRs.
• 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.

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	#4794
Related work	⚠️ 1 scoped overlap	Top overlaps are listed below; lower-confidence bulk is hidden.
Change scope	❌ 8/20	High 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: 42 registered-repo PR(s), 34 merged, 401 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	JSONbored; Gittensor profile; 42 PR(s), 401 issue(s).
Improvement	ℹ️ Insufficient signal	risk: clean · value: insufficient-signal · LLM: moderate

Linked issue satisfaction

Partially addressed
The PR adds solid concurrency tests proving the installation-token cache/mint layer never leaks tenant A's token to tenant B's calls, which supports the issue's deliverable, but the acceptance criterion specifically asks for a test where tenant A's execution context attempts to act on tenant B's repo and fails — these tests verify token issuance isolation rather than an actual attempted cross-tena

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: 42 PR(s), 401 issue(s).
• Related work: Titles/paths share 4 meaningful terms. (issue #4794, issue #4791)

Contributor next steps

• Start here: Treat this as maintainer-lane context rather than normal contributor-lane activity.
• Then work through the remaining 3 steps in the Signals table above.

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