## Release v0.51.267 — Release II (stage-r17)
Security hardening cluster — 3 @zapabob PRs (forwarded-header trust + TTS prosody validation).
### Security
| Issue/PR | Author | Hardening |
|----------|--------|-----------|
| #3640 | @zapabob | `/api/tts` per-client throttle no longer trusts `X-Forwarded-For` by default (can't spoof to evade the rate limit); forwarded IP honored only behind a trusted-proxy opt-in. |
| #3642 | @zapabob | CSRF same-origin check no longer trusts `X-Forwarded-Host`/`X-Real-Host` by default (closes a forwarded-host CSRF bypass); opt-in keeps legit reverse-proxy deploys working; default uses the real `Host`. |
| #3643 | @zapabob | Browser-provided TTS prosody (rate/pitch/volume) validated against the `±N%` / `±NHz` grammar before `edge_tts.Communicate`. |
### Attribution
Each contributor branch was **rebased onto current master and pushed back to @zapabob's fork** (native authorship preserved), so the source PRs are current/mergeable. Shipped here as one release because all three add a `[Unreleased]` CHANGELOG entry at the same location (merging individually would force a rebase-cascade). Source PRs #3640/#3642/#3643 closed as merged-via-release with credit.
### Gate
- Full pytest suite: **7779 passed, 0 failed**
- ruff: CLEAN
- revert-guard: PASS (all 3 branches rebased; master is an ancestor)
- Codex (regression): **SAFE TO SHIP** — each hardening is **default-secure AND opt-in-compatible** (no legit reverse-proxy/tunnel deploy breaks on update): CSRF forwarded-host default-off + opt-in works + normal same-origin still passes; TTS prosody rejects out-of-grammar input, legit `+N%` passes; TTS throttle ignores spoofed XFF by default.
Co-authored-by: zapabob <1920071390@campus.ouj.ac.jp>
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