`[2026-07-31]` **kimi-k3 "output cap" root-caused = a ~16384 REASONING-token ceiling, not an output cap; fix relayed to heid, NOT applied gateway-side.**

heid reported that `kimi-k3` (the primary route = Kimi Code coding endpoint `openai/k3` @ `api.kimi.com/coding/v1`) silently degraded its cross-frontier panel: on large/reasoning-heavy dispatches, `completion_tokens: 16381` **exactly**, `content` empty, `reasoning_content` ~64KB, `finish_reason: **stop**` (a truncation mislabeled as a clean stop). `max_tokens: 100000` in the request was not honored.

**Investigation arc (a clean cross-frontier-triage + verify-on-the-wire case):**
1. My first read: a flat ~16384 OUTPUT cap; fix = a LiteLLM `stop→length` relabel callback (heid's fallback ask). Confirmed the cap isn't in our LiteLLM config (no `max_tokens` clamp on the route).
2. Operator routed a fix-research pass to **dvalin-smithy-dev + bil-smithy-dev** (independent). Both CONVERGED (docs-based): `max_tokens` is a deprecated alias on Kimi/Moonshot; the canonical field is `max_completion_tokens` (default 131072, max 1M); the coding endpoint defaults output to 16384; fix = send `max_completion_tokens` + `reasoning_effort` via `extra_body` (drop_params-safe).
3. **heid's live data REFUTED the docs hypothesis:** a later dispatch hit `completion_tokens: 18455` (ABOVE 16384) cleanly, with `reasoning_tokens: 16198` (just under 16384) and content present. So COMPLETION is uncapped; the bound is on **REASONING at ~16384**. When a hard task's thinking exhausts that budget, nothing's left for content → empty answer under `stop`.
4. **I proved it on the wire** — ran heid's real 500KB failing bundle direct at both endpoints (bypassing LiteLLM so `reasoning_effort` isn't dropped): default effort → 504/timeout (the failure); **`reasoning_effort: low` → reasoning ~12–13.5k (under the ceiling), content returns (6–7.6k chars)**, on BOTH coding AND general endpoints. So re-routing to the general endpoint buys nothing — the fix is the effort param, and it works on the wire.

**THE FIX (caller-side, no shared-gateway change/restart):** send `reasoning_effort` via **`extra_body`** on kimi-k3 dispatches (`low` for large bundles). LiteLLM `drop_params: true` strips the top-level `reasoning_effort` — which is exactly why heid's earlier `reasoning_effort: low` was a no-op. `extra_body` survives drop_params (the house GLM-thinking pattern). Tradeoff: low effort = shallower reasoning, but a complete answer beats today's empty one.

**Relayed to heid to validate on a real round** (the one unconfirmed hop is whether `extra_body` survives OUR LiteLLM). **Backstop if it doesn't:** add `allowed_openai_params: ["reasoning_effort"]` to the `kimi-k3` route in the gateway config — that IS a shared-gateway change + a ~10s restart (blips all consumers), so it needs a heads-up.

Gateway = LiteLLM on ana-docker `10.250.50.70:4000`; kimi-k3 config in `stacks/litellm/conf/config.yaml` (see Recent-decisions `[2026-07-25]` Kimi K3 wiring). No gateway change was made this session. Failing dispatch on record: `01KYTASKTY3T` (jackdaw-dev bug-hunt).