docs(routing): sync combo strategy docs for Fusion (17 strategies)

CLAUDE.md

@@ -72,7 +72,7 @@ Client → /v1/chat/completions (Next.js route)
 
 API routes follow a consistent pattern: `Route → CORS preflight → Zod body validation → Optional auth (extractApiKey/isValidApiKey) → API key policy enforcement → Handler delegation (open-sse)`. No global Next.js middleware — interception is route-specific.
 
-**Combo routing** (`open-sse/services/combo.ts`): 15 strategies (priority, weighted, fill-first, round-robin, P2C, random, least-used, cost-optimized, reset-aware, reset-window, strict-random, auto, lkgp, context-optimized, context-relay). Each target calls `handleSingleModel()` which wraps `handleChatCore()` with per-target error handling and circuit breaker checks. See `docs/routing/AUTO-COMBO.md` for the 9-factor Auto-Combo scoring and `docs/architecture/RESILIENCE_GUIDE.md` for the 3 resilience layers.
+**Combo routing** (`open-sse/services/combo.ts`): 17 strategies (priority, weighted, fill-first, round-robin, P2C, random, least-used, cost-optimized, reset-aware, reset-window, headroom, strict-random, auto, lkgp, context-optimized, context-relay, fusion). Each target calls `handleSingleModel()` which wraps `handleChatCore()` with per-target error handling and circuit breaker checks. The `fusion` strategy is the exception: it fans out to a panel of models in parallel, then a judge model synthesizes one final answer (`open-sse/services/fusion.ts`). See `docs/routing/AUTO-COMBO.md` for the 9-factor Auto-Combo scoring + the full strategy table and `docs/architecture/RESILIENCE_GUIDE.md` for the 3 resilience layers.
 
 ---
 
@@ -332,7 +332,7 @@ For any non-trivial change, read the matching deep-dive first:
 | Repo navigation                               | `docs/architecture/REPOSITORY_MAP.md`                             |
 | Architecture                                  | `docs/architecture/ARCHITECTURE.md`                               |
 | Engineering reference                         | `docs/architecture/CODEBASE_DOCUMENTATION.md`                     |
-| Auto-Combo (9-factor scoring, 15 strategies)  | `docs/routing/AUTO-COMBO.md`                                      |
+| Auto-Combo (9-factor scoring, 17 strategies)  | `docs/routing/AUTO-COMBO.md`                                      |
 | Resilience (3 mechanisms)                     | `docs/architecture/RESILIENCE_GUIDE.md`                           |
 | Reasoning replay                              | `docs/routing/REASONING_REPLAY.md`                                |
 | Skills framework                              | `docs/frameworks/SKILLS.md`                                       |

README.md

@@ -23,7 +23,7 @@
 [![50+ Free](https://img.shields.io/badge/50%2B-Free_Tiers-00B894?style=for-the-badge)](#-231-ai-providers--50-free)
 [![1.6B Free Tokens/mo](https://img.shields.io/badge/1.6B-Free_Tokens%2Fmo-00B894?style=for-the-badge)](docs/reference/FREE_TIERS.md)
 [![Token Savings](https://img.shields.io/badge/up_to_95%25-Token_Savings-E17055?style=for-the-badge)](#%EF%B8%8F-save-1595-tokens--automatically)
-[![15 Strategies](https://img.shields.io/badge/15-Routing_Strategies-0984E3?style=for-the-badge)](#-combos--the-flagship)
+[![17 Strategies](https://img.shields.io/badge/17-Routing_Strategies-0984E3?style=for-the-badge)](#-combos--the-flagship)
 [![$0 to start](https://img.shields.io/badge/%240-To_Start-FDCB6E?style=for-the-badge&logoColor=black)](#-quick-start)
 
 <br/>
@@ -182,7 +182,7 @@
                           ▼
 ┌──────────────────────────────────────────────────────────┐
 │                  OmniRoute — Smart Router                  │
-│  RTK + Caveman compression · 15 routing strategies         │
+│  RTK + Caveman compression · 17 routing strategies         │
 │  Circuit breakers · TLS stealth · MCP · A2A · Guardrails   │
 └─────────────────────────┬──────────────────────────────────┘
         ┌─────────────┬────┴────────┬─────────────┐
@@ -220,7 +220,7 @@ No combo to create. Set your model to `auto` (or a variant) and OmniRoute builds
 
 ##
 
-### 🔀 Or build your own — 15 routing strategies
+### 🔀 Or build your own — 17 routing strategies
 
 | Goal                                    | Strategy / combo                                   |
 | --------------------------------------- | -------------------------------------------------- |
@@ -229,6 +229,8 @@ No combo to create. Set your model to `auto` (or a variant) and OmniRoute builds
 | 💸 Always cheapest viable model         | `cost-optimized` · `auto/cheap`                    |
 | 🧠 Hand off long context between models | `context-relay` · `context-optimized`              |
 | 🎲 Randomized / privacy routing         | `random` · `strict-random`                         |
+| 🧬 Fan out to a panel + judge synthesis | `fusion`                                           |
+| 📊 Route by remaining quota headroom    | `reset-window` · `headroom`                        |
 | 🤖 Just make it smart                   | `auto` (9-factor scoring) · `lkgp` · `reset-aware` |
 
 <sub>The Auto-Combo engine scores every candidate on **9 factors** (health, quota, cost, latency, success rate, freshness…) — see [`docs/routing/AUTO-COMBO.md`](docs/routing/AUTO-COMBO.md).</sub>
@@ -266,7 +268,7 @@ Result: 4 layers of fallback = zero downtime
 | -------------------------------------- | ----------------------------------------------------------- | ------------- |
 | 🌐 Providers                           | **231**                                                     | 20–100        |
 | 🆓 Free providers                      | **50+ (11 free forever)**                                   | 1–5           |
-| 🔀 Routing strategies                  | **15** (priority, weighted, cost-optimized, context-relay…) | 1–3           |
+| 🔀 Routing strategies                  | **17** (priority, weighted, cost-optimized, context-relay, fusion…) | 1–3           |
 | 🗜️ Token compression                   | **RTK + Caveman stacked (15–95%)**                          | None / 20–40% |
 | 🧰 Built-in MCP server                 | **87 tools, 3 transports, 30 scopes**                       | Rare          |
 | 🤝 A2A agent protocol                  | **6 skills, JSON-RPC 2.0**                                  | None          |

docs/README.md

@@ -78,7 +78,7 @@ Pluggable subsystems exposed to clients, agents, and operators.
 
 Combo routing, scoring, and replay.
 
-- [AUTO-COMBO.md](routing/AUTO-COMBO.md) — Auto-Combo (9-factor scoring, 15 strategies).
+- [AUTO-COMBO.md](routing/AUTO-COMBO.md) — Auto-Combo (9-factor scoring, 17 strategies).
 - [REASONING_REPLAY.md](routing/REASONING_REPLAY.md) — reasoning replay flow.
 
 ## security/

docs/architecture/ARCHITECTURE.md

@@ -365,9 +365,11 @@ relying on a static combo definition. It powers the `auto/*` model prefix family
 
 Key capabilities:
 
-- **14 routing strategies** (priority, weighted, fill-first, round-robin, P2C, random,
-  least-used, cost-optimized, strict-random, **auto**, lkgp, context-optimized,
-  context-relay, plus a fallback path) — auto is the headline addition in v3.8.0.
+- **17 routing strategies** (priority, weighted, fill-first, round-robin, P2C, random,
+  least-used, cost-optimized, reset-aware, reset-window, headroom, strict-random,
+  **auto**, lkgp, context-optimized, context-relay, **fusion**, plus a fallback path) —
+  auto is the headline addition in v3.8.0; `fusion` (panel fan-out + judge synthesis,
+  `open-sse/services/fusion.ts`) is new in v3.8.36.
 - **9-factor scoring**: cost, latency p95, success rate, quota headroom, lockout
   proximity, breaker state, recent failures, model availability, and tag affinity.
 - **Virtual factory** materializes ephemeral combos when no matching named combo

docs/architecture/RESILIENCE_GUIDE.md

@@ -201,7 +201,7 @@ Bounded by `comboCooldownWait` (`enabled`, `maxWaitMs` 5s, `maxAttempts` 2,
 
 ## Other Resilience Features
 
-- **14 routing strategies** (priority, weighted, round-robin, context-relay, fill-first, p2c, random, least-used, cost-optimized, reset-aware, strict-random, auto, lkgp, context-optimized) — see [AUTO-COMBO.md](../routing/AUTO-COMBO.md).
+- **17 routing strategies** (priority, weighted, round-robin, context-relay, fill-first, p2c, random, least-used, cost-optimized, reset-aware, reset-window, headroom, strict-random, auto, lkgp, context-optimized, fusion) — see [AUTO-COMBO.md](../routing/AUTO-COMBO.md).
 - **Reset-aware routing** (v3.8.0) — prioritizes connections by quota reset time.
 - **Background mode degradation** — Responses API `background: true` degraded to sync with warning.
 - **Dynamic tool limit detection** — backs off providers when tool count limits hit.

docs/comparison/OMNIROUTE_VS_ALTERNATIVES.md

@@ -16,7 +16,7 @@ Objective feature comparison vs popular open-source AI routers.
 | **Providers**                                      |          **207+**          |      ~100      |        ~50        |     ~30     |
 | **Self-hostable**                                  |             ✅             |       ✅       |        ❌         |   ⚠ paid    |
 | **OAuth providers (Claude, Codex, Copilot, etc.)** |          **15+**           |    partial     |        ❌         |     ❌      |
-| **Auto-fallback combos**                           |     **15 strategies**      | priority-based |    tier-based     |  weighted   |
+| **Auto-fallback combos**                           |     **17 strategies**      | priority-based |    tier-based     |  weighted   |
 | **Tier 1/2/3 fallback (subscription→cheap→free)**  |          ✅ + UI           |     manual     |        n/a        |   manual    |
 | **Token compression**                              | RTK (47 filters) + Caveman |      none      |       none        |    none     |
 | **Built-in MCP server**                            |   ✅ 87 tools, 30 scopes   |       ❌       |        ❌         |     ❌      |

docs/diagrams/request-pipeline.mmd

@@ -13,7 +13,7 @@ flowchart LR
   Cache -->|yes| Return["Return cached"]
   Cache -->|no| Rate["Rate limit<br/>(per-key, per-IP)"]
   Rate --> Combo{"Combo<br/>target?"}
-  Combo -->|combo| Resolve["resolveComboTargets<br/>(14 strategies)"]
+  Combo -->|combo| Resolve["resolveComboTargets<br/>(17 strategies)"]
   Resolve --> Single["handleSingleModel<br/>(per target)"]
   Combo -->|single| Single
   Single --> Translate["translateRequest<br/>(OpenAI↔Claude↔Gemini)"]

docs/frameworks/OPEN_SSE_ARCHITECTURE.md

@@ -226,7 +226,7 @@ export async function handleComboChat(body, comboId): Promise<ChatResult> {
 }
 ```
 
-Supports **15 routing strategies** (see `src/shared/constants/routingStrategies.ts`):
+Supports **17 routing strategies** (see `src/shared/constants/routingStrategies.ts`):
 
 | Strategy | Behavior |
 |----------|----------|
@@ -241,10 +241,12 @@ Supports **15 routing strategies** (see `src/shared/constants/routingStrategies.
 | `cost-optimized` | Cheapest healthy target first |
 | `reset-aware` | Aware of provider reset windows |
 | `reset-window` | Reset window-based routing |
+| `headroom` | Most remaining quota headroom first |
 | `strict-random` | Truly uniform (no quality weighting) |
 | `auto` | Use 9-factor scoring (`autoCombo/`) |
 | `lkgp` | Last known good provider first |
 | `context-optimized` | Best for long-context requests |
+| `fusion` | Fan out to a panel in parallel, then synthesize via a judge (`fusion.ts`) |
 
 ### base.ts (1170 LOC)
 

docs/guides/FEATURES.md

@@ -61,7 +61,7 @@ OpenRouter connections can store a per-connection `preset` in Advanced Settings.
 
 ## 🎨 Combos
 
-Create model routing combos with 14 strategies: priority, weighted, fill-first, round-robin, p2c (power-of-two-choices), random, least-used, cost-optimized, reset-aware, strict-random, auto, lkgp (last-known-good-provider), context-optimized, and **context-relay**. Each combo chains multiple models with automatic fallback and includes quick templates and readiness checks.
+Create model routing combos with 17 strategies: priority, weighted, fill-first, round-robin, p2c (power-of-two-choices), random, least-used, cost-optimized, reset-aware, reset-window, headroom, strict-random, auto, lkgp (last-known-good-provider), context-optimized, context-relay, and **fusion** (fan out to a panel of models in parallel, then synthesize one answer via a judge). Each combo chains multiple models with automatic fallback and includes quick templates and readiness checks.
 
 Recent combo improvements:
 

docs/openapi.yaml

@@ -6672,10 +6672,13 @@ components:
             - least-used
             - cost-optimized
             - reset-aware
+            - reset-window
+            - headroom
             - strict-random
             - auto
             - lkgp
             - context-optimized
+            - fusion
           default: priority
         nodes:
           type: array

docs/routing/AUTO-COMBO.md

@@ -147,7 +147,7 @@ Notes:
 
 ## All Routing Strategies
 
-OmniRoute's combo engine supports **14 routing strategies** (declared in `src/shared/constants/routingStrategies.ts` → `ROUTING_STRATEGY_VALUES`). The Auto Combo engine itself is exposed under the `auto` strategy; the others are available for persisted combos.
+OmniRoute's combo engine supports **17 routing strategies** (declared in `src/shared/constants/routingStrategies.ts` → `ROUTING_STRATEGY_VALUES`). The Auto Combo engine itself is exposed under the `auto` strategy; the others are available for persisted combos.
 
 | Strategy            | Description                                                        |
 | :------------------ | :----------------------------------------------------------------- |
@@ -161,12 +161,74 @@ OmniRoute's combo engine supports **14 routing strategies** (declared in `src/sh
 | `least-used`        | Pick target with lowest current load                               |
 | `cost-optimized`    | Minimize $ per request given catalog pricing                       |
 | `reset-aware` ⭐    | Prioritize by quota reset time — short reset windows ranked higher |
+| `reset-window`      | Prefer targets whose quota window resets soonest                   |
+| `headroom`          | Pick the target with the most remaining quota headroom            |
 | `strict-random`     | Random without deduplication of repeats                            |
 | `auto`              | Use Auto Combo scoring (9-factor) — **recommended**                |
 | `lkgp`              | Last-Known-Good Path (sticky route to last successful target)      |
 | `context-optimized` | Pick target with best fit for current context size                 |
+| `fusion` 🧬         | Fan out to a panel of models in parallel, then synthesize one answer via a judge (see below) |
 
-⭐ = New in v3.8.0
+⭐ = New in v3.8.0 · 🧬 = New in v3.8.36
+
+## Fusion Strategy
+
+`fusion` is the one strategy that does **not** pick a single target. It fans the prompt
+out to **every panel model in parallel**, then a configurable **judge model** synthesizes
+a single final answer from all panel responses. Ported from upstream `decolua/9router`
+(OpenRouter's Fusion design); implementation in `open-sse/services/fusion.ts`.
+
+How it works:
+
+1. **Fan-out** — the prompt is sent to every panel model at once, forced non-streaming
+   with tools stripped (the judge needs complete prose to synthesize).
+2. **Quorum-grace collection** — as soon as `minPanel` answers arrive, a short grace
+   timer starts for the stragglers, then fusion proceeds with whatever was collected.
+   This caps the slowest model's penalty on wall time, bounded by a hard timeout.
+3. **Judge synthesis** — panel answers are anonymized (`Source 1`, `Source 2`, … — so
+   the judge weighs substance, not model brand) and handed to the judge, which analyzes
+   consensus / contradictions / partial coverage / unique insights / blind spots, then
+   writes **one** authoritative answer. The judge call keeps the client's original
+   `stream` flag + tools, so streaming and downstream tool use still work.
+4. **Graceful degradation** — 0 panel answers → `503`; exactly 1 survivor → that answer
+   is returned directly (nothing to fuse); a single-model panel answers directly.
+
+### Configuration
+
+Configured on the combo's `config` blob (no schema migration — it reuses the existing
+`combos` table):
+
+| Field                              | Type     | Default   | Purpose                                                      |
+| :--------------------------------- | :------- | :-------- | :----------------------------------------------------------- |
+| `config.judgeModel`                | `string` | first panel model | Model that synthesizes the final answer            |
+| `config.fusionTuning.minPanel`     | `number` | `2`       | Successful answers required before the grace timer starts (clamped to `[2, panelSize]`) |
+| `config.fusionTuning.stragglerGraceMs` | `number` | `8000`  | How long to wait for laggards once quorum is reached         |
+| `config.fusionTuning.panelHardTimeoutMs` | `number` | `90000` | Absolute cap so one hung model can't stall the request       |
+
+Defaults live in `FUSION_DEFAULTS` (`open-sse/services/fusion.ts`).
+
+### Example
+
+```bash
+curl -X POST http://localhost:20128/api/combos \
+  -H "Authorization: Bearer <key>" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "name": "fusion-panel",
+    "strategy": "fusion",
+    "targets": [
+      { "model": "cc/claude-opus-4-7" },
+      { "model": "cx/gpt-5.5" },
+      { "model": "glm/glm-5.1" }
+    ],
+    "config": {
+      "judgeModel": "cc/claude-opus-4-7",
+      "fusionTuning": { "minPanel": 2, "stragglerGraceMs": 8000, "panelHardTimeoutMs": 90000 }
+    }
+  }'
+```
+
+Then call it like any combo: `{"model":"fusion-panel","messages":[...]}`.
 
 ## Virtual Auto-Combo Factory
 
@@ -519,5 +581,5 @@ See `docs/marketing/TIERS.md` for tier definitions and provider classification.
 | `open-sse/services/autoCombo/autoPrefix.ts`               | `auto/` prefix parser + 6 variants                                         |
 | `open-sse/services/autoCombo/virtualFactory.ts`           | Builds in-memory `AutoComboConfig` from live connections                   |
 | `open-sse/services/autoCombo/providerRegistryAccessor.ts` | Test hook for mocking provider registry                                    |
-| `src/shared/constants/routingStrategies.ts`               | `ROUTING_STRATEGY_VALUES` (14 strategies)                                  |
+| `src/shared/constants/routingStrategies.ts`               | `ROUTING_STRATEGY_VALUES` (17 strategies)                                  |
 | `src/sse/handlers/chat.ts`                                | Integration: auto-prefix short-circuit                                     |