fix(orb): make self-host webhook-delivery loss visible to operators

[JSONbored]

Summary

Makes self-host webhook-delivery loss visible to operators — the failure class a self-host operator most needs to trust ("the container looks alive but reviews nothing"). The self-host Sentry forwarder only forwards level:"error"/"fatal" lines, so these losses were silent or warn-only:

1. Push-path relay drop (retryFailedRelays, relay.ts): a relay event abandoned after its 1h TTL / 5-retry budget was logged at level:"warn" → invisible to Sentry. Escalated to level:"error" (orb_relay_events_dropped).
2. Pull-path relay drop (pruneRelayPending, relay.ts): a pull-mode (NAT/tailnet) container offline past the 24h retention window lost its queued webhooks with no log at all — the push path was hardened but the functionally-identical pull path wasn't. Added a distinct orb_relay_pending_dropped at level:"error" (distinct event name so operators can tell pull-mode loss from push-mode loss).
3. Boot relay-registration failure (server.ts): registerOrbRelayTarget returning "failed" was logged at info (no level) and the .catch was swallowed (() => {}). A failed registration means the central Orb never forwards this install's webhooks here — the container reviews nothing. Now "failed" logs at level:"error" (selfhost_orb_relay_register_failed) and the catch routes to captureError (already imported).

Surfaced by the 2026-06-27 review-pipeline hardening audit (observability) — consolidates the "self-host delivery integrity" cluster the audit's completeness-critic called out. (The companion retryFailedRelays not_forwardable retry-semantics fix is deferred to its own PR — it changes forwardOrbEvent's return type and ripples into the webhook handler.)

Scope

• Conventional Commit title; focused (relay.ts + server.ts + the relay test).
• No site//CNAME/Pages; follows CONTRIBUTING.md.
• Small self-evident extension of the fix(orb): surface dropped relay events + correct the stale MCP-501 self-host doc #1481 relay-drop-log / fix(observability): capture AI-CLI stderr + surface exhausted provider failures to Sentry #1605 Sentry line.

Validation

• git diff --check · actionlint · typecheck
• test:coverage — updated the exhausted-budget drop test to assert console.error + "level":"error"; extended the TTL-prune test to assert orb_relay_pending_dropped at error level. Both changes>0/changes===0 arms remain covered (the many no-stale enqueue/retry paths). server.ts is codecov-ignored (boot wiring).
• test:workers · build:mcp · test:mcp-pack · ui:* · npm audit --audit-level=moderate

If any required check was skipped, explain why:

• No migration/OpenAPI/cf-typegen: logging/escalation only.

Safety

• No secrets/wallets/trust-scores exposed — logs carry only an event name + a dropped-count.
• No public GitHub text change · auth/CORS N/A.

Notes

• relay.ts runs on the cloud Orb (gittensory-api, auto-deploys on merge); the server.ts boot wiring runs on the self-host engine (ships on the next rebuild).

[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 95.52%. Comparing base (a2ebeb1) to head (d9d9b81).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1628   +/-   ##
=======================================
  Coverage   95.52%   95.52%           
=======================================
  Files         204      204           
  Lines       22057    22059    +2     
  Branches     7967     7968    +1     
=======================================
+ Hits        21070    21072    +2     
  Misses        412      412           
  Partials      575      575           

Files with missing lines	Coverage Δ
src/orb/relay.ts	100.00% <100.00%> (ø)

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