feat(agent-actions): add an install-wide contributor open-item cap across repos

[JSONbored]

Summary

• Adds an optional, install-scoped GLOBAL_CONTRIBUTOR_OPEN_ITEM_CAP env var (src/env.d.ts, parsed by the new src/settings/global-contributor-cap.ts) so a self-hosted install that gates multiple repos can cap a contributor's SUM of open PRs+issues across every repo it tracks, not just one repo. Off by default (unset/invalid ⇒ no cap), mirroring global_contributor_blacklist's tenant-free-singleton design (src/db/repositories.ts:589 getGlobalContributorBlacklist) but as an env var since the issue doesn't need a maintainer-editable value, just an install operator's own config.
• Adds countOpenItemsForAuthorAcrossRepos (src/db/repositories.ts), a same-database aggregate query summing open PRs + open issues for one author with no repoFullName filter, unlike the existing countOpenPullRequests/countOpenIssues. No cross-instance networking — purely a query against the same D1/SQLite database every repo on the install already shares.
• Wires the install-wide check into both existing contributor-cap call sites in src/queue/processors.ts (runAgentMaintenancePlanAndExecute for PRs, maybeCloseIssueOverContributorCap for issues), IN ADDITION TO the existing per-repo contributorOpenPrCap/contributorOpenIssueCap checks, in the same short-circuit block. Reuses the existing autoCloseExemptLogins shared exemption list (src/settings/auto-close-exempt.ts) so a maintainer-named login is exempt from the install-wide cap exactly like the per-repo caps and review-nag cooldown.
• Reuses the existing contributorCapMatch/closeKind: "contributor_cap" short-circuit in src/settings/agent-actions.ts — no new disposition type. Added an optional scope?: "repository" | "install" field so the close-comment wording is accurate ("this repository's configured limit" vs. "this install's configured limit (across every repository it gates, combined)") without changing the closeKind, label, or overall message shape; absent scope defaults to the original repository wording for back-compat with every existing caller.

Scope

• The PR title follows type(scope): short summary Conventional Commit format, for example fix(api): restore profile access checks.
• 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 an issue, or this is small enough that the summary explains why an issue is not needed.

Validation

• git diff --check
• npm run actionlint
• npm run typecheck
• npm run test:coverage locally; codecov/patch requires ≥99% coverage of the lines AND branches you changed (aim for 100% on your diff so CI variance does not fail near the threshold). Global coverage is a non-blocking trend with a loose 90% backstop, not the gate.
• npm run test:workers
• npm run build:mcp
• npm run test:mcp-pack
• npm run ui:openapi:check
• npm run ui:lint
• npm run ui:typecheck
• npm run ui:build
• npm audit --audit-level=moderate
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries

Ran the full npm run test:ci gate (actionlint, migrations check, cf-typegen check, typecheck, full unsharded coverage suite, workers tests, MCP build/pack, miner build, REES tests, UI openapi/settings-parity/version-audit/lint/typecheck/test/build) — all green, 354 test files / 6751 tests passed, 0 failures. npm audit --audit-level=moderate reports 0 vulnerabilities.

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.
• API/OpenAPI/MCP behavior is updated and tested where needed. (No public API/OpenAPI surface changed — this is an internal maintenance-action input, so no OpenAPI regen was required.)
• UI changes use live API data or real empty/error/loading states, not production mock/demo fallbacks. (N/A — no UI changed.)
• Visible UI changes include a UI Evidence section below with screenshots. (N/A — backend-only change, no visible UI.)
• Public docs/changelogs are updated where needed; changelogs are only edited for release-prep PRs. (No CHANGELOG.md edit.)

UI Evidence

N/A — this is a backend-only change (no UI surfaces touched).

Notes

• The cap is deliberately an env var (GLOBAL_CONTRIBUTOR_OPEN_ITEM_CAP), not a per-repo .gittensory.yml/DB field, because it aggregates ACROSS repos and therefore cannot be "this repo's" setting — it belongs to the install as a whole. It is not added to wrangler.jsonc's hosted vars block (mirrors how other self-host-oriented numeric env vars like AI_BYOK_DAILY_REPO_LIMIT are handled — declared only in src/env.d.ts), so it does not require cf-typegen regeneration.
• Left out of scope: no maintainer-facing settings-row UI for this cap (an install operator sets the env var directly), since the issue explicitly frames this as "likely an env var" and off-by-default is the hard requirement, not a maintainer dashboard control.

Closes #2562

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.11%. Comparing base (642b12d) to head (41637eb).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2678   +/-   ##
=======================================
  Coverage   96.10%   96.11%           
=======================================
  Files         237      238    +1     
  Lines       26538    26563   +25     
  Branches     9624     9634   +10     
=======================================
+ Hits        25505    25530   +25     
  Misses        424      424           
  Partials      609      609           

Files with missing lines	Coverage Δ
src/db/repositories.ts	96.60% <100.00%> (+<0.01%)	⬆️
src/queue/processors.ts	92.63% <100.00%> (+0.05%)	⬆️
src/settings/agent-actions.ts	94.32% <100.00%> (+0.04%)	⬆️
src/settings/global-contributor-cap.ts	100.00% <100.00%> (ø)

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