[diegosouzapw]

⚠️ base-red inherited: #9737 — 13 HARD failures pre-existing on release/v3.8.50, none from this PR's changes. See the release-green issue for details.

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Closes #9305

Two bugs fixed:

Bug A — Env var too narrow: sseCommentsEnabled() only recognized "off" as a disabling value, ignoring "0", "false", and "no" (the standard OmniRoute convention).

[xiaoyaner0201]

Thanks for picking this up. This overlaps with the Draft I published earlier as #9378, and the production behavior in this PR matches the same core fix.

I ran the stronger finalization test from #9378 against this PR's exact head 6c47da73595963e7421ab7bb2e68c559a16127ce in an isolated test-only worktree. It passed 6/6 across both upstream [DONE] and natural-EOF finalization, including:

• disabled comments remove all final : x-omniroute-* metadata;
• default/explicitly enabled behavior still emits metadata;
• ordinary chunks, synthetic finish output, and [DONE] ordering remain intact;
• usage/accounting completion, pending-request cleanup, and logger/client ordering remain intact.

Your native tests/unit/sseHeartbeat.test.ts also passed 4/4 on that exact head. The current test changes here validate the environment-value parser and heartbeat path, but do not directly exercise final metadata emission; the focused test is tests/unit/sse-comments-optout-9305.test.ts in #9378 if you want to copy or cherry-pick that coverage into this maintainer-owned PR.

I will keep #9378 Draft and avoid competing updates while this PR is active.