docs: add opencode-go provider tier documentation

docs/guide/agent-model-matching.md

@@ -64,8 +64,8 @@ These agents have Claude-optimized prompts — long, detailed, mechanics-driven.
 
 | Agent        | Role              | Fallback Chain                         | Notes                                                                                             |
 | ------------ | ----------------- | -------------------------------------- | ------------------------------------------------------------------------------------------------- |
-| **Sisyphus** | Main orchestrator | Claude Opus → K2P5 → Kimi K2.5 → GPT-5.4 → GLM 5 → Big Pickle | Claude-family first. GPT-5.4 has dedicated prompt support. Kimi/GLM as intermediate fallbacks. |
+| **Sisyphus** | Main orchestrator | Claude Opus → opencode-go/kimi-k2.5 → K2P5 → GPT-5.4 → GLM-5 → Big Pickle | Claude-family first. GPT-5.4 has dedicated prompt support. Kimi/GLM as intermediate fallbacks. |
-| **Metis**    | Plan gap analyzer | Claude Opus → GPT-5.4 → Gemini 3.1 Pro | Claude preferred, GPT acceptable fallback.                                                        |
+| **Metis**    | Plan gap analyzer | Claude Opus → opencode-go/glm-5 → K2P5 | Claude preferred. Uses opencode-go for reliable GLM-5 access.                                     |
 
 ### Dual-Prompt Agents → Claude preferred, GPT supported
 
@@ -73,8 +73,8 @@ These agents ship separate prompts for Claude and GPT families. They auto-detect
 
 | Agent          | Role              | Fallback Chain                         | Notes                                                                |
 | -------------- | ----------------- | -------------------------------------- | -------------------------------------------------------------------- |
-| **Prometheus** | Strategic planner | Claude Opus → GPT-5.4 → Gemini 3.1 Pro | Interview-mode planning. GPT prompt is compact and principle-driven. |
+| **Prometheus** | Strategic planner | Claude Opus → GPT-5.4 → opencode-go/glm-5 → Gemini 3.1 Pro | Interview-mode planning. GPT prompt is compact and principle-driven. |
-| **Atlas**      | Todo orchestrator | Claude Sonnet 4.6 → GPT-5.4            | Claude first, GPT-5.4 as the current fallback path.                  |
+| **Atlas**      | Todo orchestrator | Claude Sonnet → opencode-go/kimi-k2.5  | Claude first, opencode-go as the current fallback path.              |
 
 ### Deep Specialists → GPT
 
@@ -92,9 +92,9 @@ These agents do grep, search, and retrieval. They intentionally use the fastest,
 
 | Agent                 | Role               | Fallback Chain                                 | Notes                                                 |
 | --------------------- | ------------------ | ---------------------------------------------- | ----------------------------------------------------- |
-| **Explore**           | Fast codebase grep | Grok Code Fast → MiniMax → Haiku → GPT-5-Nano  | Speed is everything. Fire 10 in parallel.             |
+| **Explore**           | Fast codebase grep | Grok Code Fast → opencode-go/minimax-m2.5 → MiniMax Free → Haiku → GPT-5-Nano | Speed is everything. Fire 10 in parallel.             |
-| **Librarian**         | Docs/code search   | Gemini Flash → MiniMax → Big Pickle            | Doc retrieval doesn't need deep reasoning.            |
+| **Librarian**         | Docs/code search   | opencode-go/minimax-m2.5 → MiniMax Free → Haiku → GPT-5-Nano                  | Doc retrieval doesn't need deep reasoning.            |
-| **Multimodal Looker** | Vision/screenshots | GPT-5.3 Codex → K2P5 → Gemini Flash → GLM-4.6v | Uses the first available multimodal-capable fallback. |
+| **Multimodal Looker** | Vision/screenshots | GPT-5.4 → opencode-go/kimi-k2.5 → GLM-4.6v → GPT-5-Nano                       | Uses the first available multimodal-capable fallback. |
 
 ---
 
@@ -132,6 +132,26 @@ Principle-driven, explicit reasoning, deep technical capability. Best for agents
 | **Grok Code Fast 1** | Blazing fast code grep. Default for Explore agent.                                                           |
 | **MiniMax M2.5**     | Fast and smart. Good for utility tasks and search/retrieval.                                                 |
 
+### OpenCode Go
+
+A premium subscription tier ($10/month) that provides reliable access to Chinese frontier models through OpenCode's infrastructure.
+
+**Available Models:**
+
+| Model                    | Use Case                                                              |
+| ------------------------ | --------------------------------------------------------------------- |
+| **opencode-go/kimi-k2.5** | Vision-capable, Claude-like reasoning. Used by Sisyphus, Atlas, Sisyphus-Junior, Multimodal Looker. |
+| **opencode-go/glm-5**     | Text-only orchestration model. Used by Oracle, Prometheus, Metis, Momus.                           |
+| **opencode-go/minimax-m2.5** | Ultra-cheap, fast responses. Used by Librarian, Explore for utility work.                          |
+
+**When It Gets Used:**
+
+OpenCode Go models appear in fallback chains as intermediate options. They bridge the gap between premium Claude access and free-tier alternatives. The system tries OpenCode Go models before falling back to free tiers (MiniMax Free, Big Pickle) or GPT alternatives.
+
+**Go-Only Scenarios:**
+
+Some model identifiers like `k2p5` (paid Kimi K2.5) and `glm-5` may only be available through OpenCode Go subscription in certain regions. When configured with these short identifiers, the system resolves them through the opencode-go provider first.
+
 ### About Free-Tier Fallbacks
 
 You may see model names like `kimi-k2.5-free`, `minimax-m2.5-free`, or `big-pickle` (GLM 4.6) in the source code or logs. These are free-tier versions of the same model families, served through the OpenCode Zen provider. They exist as lower-priority entries in fallback chains.

docs/guide/installation.md

@@ -68,7 +68,12 @@ Ask the user these questions to determine CLI options:
    - If **yes** → `--zai-coding-plan=yes`
    - If **no** → `--zai-coding-plan=no` (default)
 
-**Provider Priority**: Native (anthropic/, openai/, google/) > GitHub Copilot > OpenCode Zen > Z.ai Coding Plan
+7. **Do you have an OpenCode Go subscription?**
+   - OpenCode Go is a $10/month subscription providing access to GLM-5, Kimi K2.5, and MiniMax M2.5 models
+   - If **yes** → `--opencode-go=yes`
+   - If **no** → `--opencode-go=no` (default)
+
+**Provider Priority**: Native (anthropic/, openai/, google/) > Kimi for Coding > GitHub Copilot > OpenCode Go > OpenCode Zen > Z.ai Coding Plan
 
 MUST STRONGLY WARNING, WHEN USER SAID THEY DON'T HAVE CLAUDE SUBSCRIPTION, SISYPHUS AGENT MIGHT NOT WORK IDEALLY.
 
@@ -91,7 +96,7 @@ Spawn a subagent to handle installation and report back - to save context.
 Based on user's answers, run the CLI installer with appropriate flags:
 
 ```bash
-bunx oh-my-opencode install --no-tui --claude=<yes|no|max20> --gemini=<yes|no> --copilot=<yes|no> [--openai=<yes|no>] [--opencode-zen=<yes|no>] [--zai-coding-plan=<yes|no>]
+bunx oh-my-opencode install --no-tui --claude=<yes|no|max20> --gemini=<yes|no> --copilot=<yes|no> [--openai=<yes|no>] [--opencode-go=<yes|no>] [--opencode-zen=<yes|no>] [--zai-coding-plan=<yes|no>]
 ```
 
 **Examples:**
@@ -102,6 +107,7 @@ bunx oh-my-opencode install --no-tui --claude=<yes|no|max20> --gemini=<yes|no> -
 - User has only GitHub Copilot: `bunx oh-my-opencode install --no-tui --claude=no --gemini=no --copilot=yes`
 - User has Z.ai for Librarian: `bunx oh-my-opencode install --no-tui --claude=yes --gemini=no --copilot=no --zai-coding-plan=yes`
 - User has only OpenCode Zen: `bunx oh-my-opencode install --no-tui --claude=no --gemini=no --copilot=no --opencode-zen=yes`
+- User has OpenCode Go only: `bunx oh-my-opencode install --no-tui --claude=no --openai=no --gemini=no --copilot=no --opencode-go=yes`
 - User has no subscriptions: `bunx oh-my-opencode install --no-tui --claude=no --gemini=no --copilot=no`
 
 The CLI will: