docs: record thinking-switch findings and capability design (issue #5, #6)

Findings: live-API measurements across MiniMax M3/M2.7/M2.5, qwen and
deepseek, plus a survey of how nine unified gateways model per-model
parameter divergence. Key facts: reasoning_effort is MiniMax's real
switch, M2.x reasoning is mandatory and cannot be disabled, and the
relay's local token-count fallback silently drops reasoning_tokens.

Design: keep the parameter shape at provider level, push capability
down to model level, split "unknown" / "unsupported" / "no opinion"
into three distinct values, and fail at assembly time when a model
cannot honour enable_thinking=False.

research-wiki/index.md

@@ -1,8 +1,8 @@
 # Research Wiki 索引
 
-> 自动生成，更新时间：2026-08-01 01:58 UTC
+> 自动生成，更新时间：2026-08-02 09:38 UTC
 
-## design (20)
+## design (21)
 - [2026-07-20-m1-core-design](designs/2026-07-20-m1-core-design.md) `design:2026-07-20-m1-core-design`
 - [2026-07-20-m2-distributed-design](designs/2026-07-20-m2-distributed-design.md) `design:2026-07-20-m2-distributed-design`
 - [2026-07-21-m25-resilience-design](designs/2026-07-21-m25-resilience-design.md) `design:2026-07-21-m25-resilience-design`
@@ -22,9 +22,10 @@
 - [M3 OCR 端口族设计](designs/m3-ocr.md) `design:m3-ocr`
 - [M4 迁移验证设计(GovDoc→CHS,发 v1.0)](designs/m4-migration.md) `design:m4-migration`
 - [响应可观测字段扩展(Issue #3)](designs/response-observability-fields.md) `design:response-observability-fields`
+- [推理开关能力建模与 reasoning_tokens 采集(issue #5 + #6)](designs/2026-08-02-thinking-capability-design.md) `design:2026-08-02-thinking-capability-design`
 - [采样参数透传设计(issue #4)](designs/sampling-params.md) `design:sampling-params`
 
-## finding (11)
+## finding (12)
 - [2026-07-20-m2-soak-workload](findings/2026-07-20-m2-soak-workload.md) `finding:2026-07-20-m2-soak-workload`
 - [2026-07-21-m25-acceptance](findings/2026-07-21-m25-acceptance.md) `finding:2026-07-21-m25-acceptance`
 - [2026-07-21-p6-soak-baseline](findings/2026-07-21-p6-soak-baseline.md) `finding:2026-07-21-p6-soak-baseline`
@@ -36,6 +37,7 @@
 - [M4 迁移验收(GovDoc+CHS)](findings/m4-acceptance.md) `finding:m4-acceptance`
 - [P6 混合浸泡首跑基线与记分板三重伪击穿修复](findings/p6-soak-baseline.md) `finding:p6-soak-baseline`
 - [P7 OCR soak 验收: 99.73% 与 13 不变量全 PASS](findings/p7-ocr-soak.md) `finding:p7-ocr-soak`
+- [推理开关与 reasoning_tokens: 供应商实测与业界做法](findings/2026-08-02-thinking-switch-and-reasoning-tokens.md) `finding:2026-08-02-thinking-switch-and-reasoning-tokens`
 
 ## plan (16)
 - [2026-07-20-m1-core-plan](plans/2026-07-20-m1-core-plan.md) `plan:2026-07-20-m1-core-plan`