fix(engine): normalize worktree-pool maxConcurrency so a NaN cap can't disable it

[reyanthony062001-ops]

Summary

availableWorktreeSlots and acquireWorktree in packages/loopover-engine/src/miner/worktree-pool.ts read WorktreePoolConfig.maxConcurrency directly in their comparisons with no normalization. If the cap arrives as NaN (e.g. a caller derives it from Number(someUnparsableConfigValue) and doesn't guard the result), every comparison against it is false — length >= NaN never holds — so at_capacity never fires and the pool allocates worktrees without bound, directly contradicting the type's own documented contract ("A non-positive cap allocates nothing"). availableWorktreeSlots also returns NaN, breaking any caller that treats it as a real remaining-slots count.

The fix adds a small finiteNonNegativeInt helper (mirroring the exact pattern already used in governor/rate-limit.ts, governor/budget-cap.ts, and tenant-quota.ts in this same package) and normalizes config.maxConcurrency through it at both read sites: a non-finite or negative cap floors to 0 (the documented "allocates nothing" behavior), and a fractional cap floors down. No public signature or behavior change for a valid positive cap.

Closes #5828

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• This PR is focused and does not mix unrelated backend, UI, MCP, docs, dependency, and deploy changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• I linked a currently open issue this PR resolves (Closes #5828).

Validation

• git diff --check — clean
• npm run actionlint — no workflow changes
• npm run typecheck — passes (whole project, against the rebuilt @loopover/engine)
• npm run test:coverage — the two changed engine lines and both arms of the new finiteNonNegativeInt (finite→floor, non-finite→0) are exercised by the new regression tests plus the existing positive-cap tests, so codecov/patch on the diff is 100%. test/unit/miner-worktree-pool.test.ts passes 10/10; the new NaN and fractional cases fail on the pre-fix code and pass after. packages/loopover-engine own suite: 553/553.
• npm run test:workers — unaffected (pure in-memory engine scheduling logic, no worker changes)
• npm run build:mcp / test:mcp-pack — unaffected (no MCP changes)
• npm run ui:openapi:check / ui:lint / ui:typecheck / ui:build — unaffected (no UI/OpenAPI/route changes)
• npm audit --audit-level=moderate — no dependency changes
• New or changed behavior has unit tests — regression tests for maxConcurrency: NaN, -1, and a fractional value, asserting the pool refuses allocation (or floors correctly) in each case

If any required check was skipped, explain why:

• Change is confined to one engine module (worktree-pool.ts, +the helper) plus its test. It introduces no workflow, MCP, UI, OpenAPI, or dependency changes. I additionally ran npm run engine-parity:drift-check (ok — this module is engine-only, not a src/{review,settings,signals} twin) and the backend drift checks (docs, manifest, command-reference, selfhost env-reference), all green.

Safety

• No secrets, wallet details, hotkeys, coldkeys, user PATs, private keys, raw trust scores, private rankings, or private maintainer evidence are exposed.
• Public GitHub text stays sanitized, low-noise, and does not imply compensation guarantees or optimization tactics.
• Auth, cookie, CORS, GitHub App, Cloudflare, or session changes include negative-path tests — N/A (none).
• API/OpenAPI/MCP behavior is updated and tested where needed — N/A (none).
• UI changes use live API data or real empty/error/loading states — N/A (no UI changes).
• Visible UI changes include a UI Evidence section — N/A (no UI/frontend/docs/extension changes).
• Public docs/changelogs are updated where needed — N/A.

Notes

• The normalization matches the module's existing "non-positive cap allocates nothing" contract exactly — an invalid cap now behaves identically to a documented 0 cap rather than silently disabling the limit — so no caller relying on the current documented semantics changes behavior; only the previously-undefined invalid-input case is now defined.

[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 95.17%. Comparing base (d3bf13b) to head (3e741af).
⚠️ Report is 27 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6041   +/-   ##
=======================================
  Coverage   95.16%   95.17%           
=======================================
  Files         593      592    -1     
  Lines       46955    46967   +12     
  Branches    15006    15007    +1     
=======================================
+ Hits        44685    44700   +15     
+ Misses       1512     1511    -1     
+ Partials      758      756    -2     

Flag	Coverage Δ
shard-1	43.96% <0.00%> (+0.02%)	⬆️
shard-2	36.52% <0.00%> (-0.02%)	⬇️
shard-3	32.14% <100.00%> (+0.06%)	⬆️
shard-4	32.92% <0.00%> (-0.10%)	⬇️
shard-5	31.50% <0.00%> (+0.14%)	⬆️
shard-6	44.59% <0.00%> (+<0.01%)	⬆️

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

Files with missing lines	Coverage Δ
...ackages/loopover-engine/src/miner/worktree-pool.ts	100.00% <100.00%> (ø)

... and 5 files with indirect coverage changes

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✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-15 07:39:08 UTC}

2 files · 1 AI reviewer · no blockers · readiness 98/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This PR adds a `finiteNonNegativeInt` normalizer at both `maxConcurrency` read sites in `worktree-pool.ts`, closing a real bug where a NaN/negative/fractional cap would make `length >= config.maxConcurrency` always false and disable the allocation limit entirely. The fix is applied at the correct layer (the two actual comparison/subtraction sites), mirrors an existing pattern used elsewhere in the package, and is covered by three new tests exercising NaN, negative, and fractional inputs against both `availableWorktreeSlots` and `acquireWorktree`. This is a small, well-targeted, correctly-scoped fix tied to an open issue (#5828).

Nits — 3 non-blocking

• The helper `finiteNonNegativeInt` is a local, unexported duplicate of logic already living in `governor/rate-limit.ts`/`governor/budget-cap.ts`/`tenant-quota.ts` per the PR description — consider hoisting it to a shared util to avoid drift across four copies.
• The doc comment on `finiteNonNegativeInt` (worktree-pool.ts) is fairly long for a 1-line helper; could be trimmed to the essential behavior.
• Consider extracting `finiteNonNegativeInt` into a shared internal module now that it exists in four places, so future changes to the normalization rule don't need to be replicated by hand.

Signal	Result	Evidence
Code review	✅ No blockers	1 reviewer
Linked issue	✅ Linked	#5828
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: 28 registered-repo PR(s), 16 merged, 1 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	reyanthony062001-ops; Gittensor profile; 28 PR(s), 1 issue(s).
Gate result	✅ Passing	No configured blocker found.
Improvement	✅ Minor	risk: clean · value: minor · LLM: moderate

Linked issue satisfaction

Addressed
The diff adds a finiteNonNegativeInt-style normalization helper applied at both availableWorktreeSlots and acquireWorktree, correctly flooring non-finite/negative values to 0 and fractional values down, matching the issue's requirements exactly.

Review context

• Author: reyanthony062001-ops
• 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: 28 PR(s), 1 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Keep the PR focused and include validation evidence before maintainer review.

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.