[maxmad64bis]

Summary

ALLOW_MULTI_CONNECTIONS_PER_COMPAT_NODE looks like it gates multi-connection support
for compat providers, but nothing checks it anymore. Traced the history: it did govern
real behavior at launch (v1.0.0) — a single-connection guard in route.ts. Commit
5b5e21a99 (fix: resolve v3.7.0 stabilization issues, closing #1566 — "OpenAI
Compatible node: support multiple connections") deliberately removed that guard so
compat providers behave like first-party ones, but left the env-var read
(allowMultipleCompatibleConnections) and the matching Settings flag definition behind.
Toggling this flag today does nothing. Removed the flag definition and the dead read,
without wiring it up to gate anything again — that would reverse #1566's decision, which
is a separate call from a dead-code cleanup.

⚠️ base-red inherited: #9985

Related Issues

Cleans up dead code left over from #1566 (resolved by 5b5e21a99). No new issue.

Validation

• Change type: other (dead-code removal, zero behavior change)
• Focused tests: feature-flags-settings.test.ts
• npm run lint
• No behavior changed — the updated flag-count assertion is the regression guard

Tests Added Or Updated

tests/unit/feature-flags-settings.test.ts — EXPECTED_FEATURE_FLAG_COUNT decremented
by 1 to match the removed definition. The other assertions reference the constant by
name, so they didn't need touching.

Coverage Notes

Covered by that same count assertion — it's the exact regression guard for "a flag got
removed".

Reviewer Notes

The flag's i18n key (featureFlagAllowMultiConnectionsPerCompatNodeDescription) only had
one reference — its own declaration — so no locale files needed touching there. Separately,
src/i18n/messages/*.json (20 locales) still carries an older, differently-named
featureFlags.definitions.ALLOW_MULTI_CONNECTIONS_PER_COMPAT_NODE entry that predates
this PR and isn't wired to anything either — left alone here since it's a different
cleanup (i18n message catalog vs. flag definition), happy to follow up separately if
useful. Also removed the matching doc references (.env.example,
docs/architecture/ARCHITECTURE.md, docs/reference/ENVIRONMENT.md,
docs/reference/FEATURE_FLAGS.md). See #10973 for the sibling cleanup — the
existingConnections variable the removed guard also read is dead for the same reason,
from the same 5b5e21a99 commit, split into its own PR since it doesn't touch a Settings
surface.