docs(changelog): credit #3598 (chatCore modularization) + #3588 (combo reasoning buffer)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -2,8 +2,13 @@
 
 ## [Unreleased]
 
+### ♻️ Code Quality
+
+- **refactor(chatCore):** extract the chatCore request phases — idempotency check, semantic cache check, common request sanitization, and memory/skills injection — into dedicated `open-sse/handlers/chatCore/` modules (`idempotency.ts`, `semanticCache.ts`, `sanitization.ts`, `memorySkillsInjection.ts`), slimming the monolithic handler with no behavior change. (Maintainer follow-up: re-derive `idempotencyKey` at the Phase 9.2 save site after the check moved into the module, fixing a `ReferenceError` on successful non-cached responses.) ([#3598](https://github.com/diegosouzapw/OmniRoute/pull/3598) — thanks @oyi77)
+
 ### 🔧 Bug Fixes
 
+- **fix(routing):** reasoning models (deepseek-v4-flash, nemotron, etc.) no longer return empty content in combo routing when they spend all of `max_tokens` on reasoning — `validateResponseQuality` now rejects an empty-content-but-`reasoning_content` response when reasoning consumed ≥90% of completion tokens (so the combo loop retries/falls back), and reasoning models receive a `max_tokens` buffer (+50%, +1000 floor) so reasoning and content both fit. (Maintainer follow-up: the round-robin buffer is applied to a per-attempt copy so it does not compound across models/retries — `4096 → 6144 → 9216 → …`.) ([#3588](https://github.com/diegosouzapw/OmniRoute/pull/3588) — thanks @herjarsa)
 - **fix(routing):** a valid `max_tokens`-truncated upstream response is no longer misclassified as empty content and rewritten into a fake 502 — `isEmptyContentResponse()` flagged any Claude `content:[]` / OpenAI empty-choice payload regardless of `stop_reason`/`finish_reason`, so a Claude Code `max_tokens: 1` connectivity ping (HTTP 200, `stop_reason:"max_tokens"`, empty content) became a synthetic `502 "Provider returned empty content"` and triggered a needless family fallback. The guard now treats a terminal truncation/tool signal (Claude `stop_reason` `max_tokens`/`tool_use`, OpenAI `finish_reason` `length`/`tool_calls`) as a legitimate completion; genuinely empty responses (no terminal reason, or `stop`/`end_turn` with empty content) are still caught. ([#3572](https://github.com/diegosouzapw/OmniRoute/issues/3572))
 - **fix(api):** `/v1/completions` now returns the legacy OpenAI Completions shape (`object:"text_completion"`, `choices[].text`) instead of chat payloads (`choices[].message|delta.content`) — the endpoint routes internally through the chat pipeline, so legacy Completion clients like TabbyML's `openai/completion` backend crashed with `missing field "text"`. The response (both non-streaming JSON and the SSE stream) is now translated back to the text-completion shape; `[DONE]` and error bodies pass through unchanged. ([#3571](https://github.com/diegosouzapw/OmniRoute/issues/3571))
 - **fix(usage):** the z.ai/GLM coding-plan quota card no longer shows "Monthly 0%" — coding plans have no monthly cap (only 5-hour windows), so the quota API reports the `TIME_LIMIT` ("Monthly") entry with `total=0`, and the `total>0 ? … : 0` fallback rendered a misleading 0% remaining (which can skew downstream model-choice). With no absolute cap the remaining percentage now falls back to the percentage-derived value (full/100% when 0% used). ([#3580](https://github.com/diegosouzapw/OmniRoute/issues/3580))