docs: audit and update agent lists, models, and fallback chains

- Update README.md to prioritize Primary Agents (Sisyphus, Hephaestus, Prometheus, Atlas, Junior)
- Update overview.md and features.md to distinguish Primary Agents from Specialist Subagents
- Update Librarian and Multimodal-Looker models in docs to match source code fallback chains
- Ensure accuracy of agent descriptions and roles

docs/guide/installation.md

@@ -344,8 +344,8 @@ These agents do search, grep, and retrieval. They intentionally use fast, cheap
 | Agent                 | Role               | Default Chain                                                          | Design Rationale                                               |
 | --------------------- | ------------------ | ---------------------------------------------------------------------- | -------------------------------------------------------------- |
 | **Explore**           | Fast codebase grep | MiniMax M2.5 Free → Grok Code Fast → MiniMax M2.5 → Haiku → GPT-5-Nano | Speed is everything. Grok is blazing fast for grep.            |
-| **Librarian**         | Docs/code search   | MiniMax M2.5 Free → Gemini Flash → Big Pickle                          | Entirely free-tier. Doc retrieval doesn't need deep reasoning. |
-| **Multimodal Looker** | Vision/screenshots | Kimi K2.5 → Kimi Free → Gemini Flash → GPT-5.4 → GLM-4.6v              | Kimi excels at multimodal understanding.                       |
+| **Librarian**         | Docs/code search   | MiniMax M2.5 → MiniMax Free → Haiku → Nano                     | Fast, cheap models for search.                                 |
+| **Multimodal Looker** | Vision/screenshots | GPT-5.4 → Kimi K2.5 → GLM-4.6v → GPT-5-Nano                    | Strong vision capabilities.                                    |
 
 #### Why Different Models Need Different Prompts
 

docs/guide/overview.md

@@ -60,10 +60,11 @@ User Request
     ↓
     ├─→ [Prometheus] — Strategic planning (interview mode)
     ├─→ [Atlas] — Todo orchestration and execution
-    ├─→ [Oracle] — Architecture consultation
-    ├─→ [Librarian] — Documentation/code search
-    ├─→ [Explore] — Fast codebase grep
-    └─→ [Category-based agents] — Specialized by task type
+    ├─→ [Specialist Subagents]
+    │     ├─→ [Oracle] — Architecture consultation
+    │     ├─→ [Librarian] — Documentation/code search
+    │     └─→ [Explore] — Fast codebase grep
+    └─→ [Sisyphus-Junior] — Category-based executor
 ```
 
 When Sisyphus delegates to a subagent, it doesn't pick a model name. It picks a **category** — `visual-engineering`, `ultrabrain`, `quick`, `deep`. The category automatically maps to the right model. You touch nothing.
@@ -116,17 +117,20 @@ Atlas executes Prometheus plans. Distributes tasks to specialized subagents. Acc
 
 Run `/start-work` to activate Atlas on your latest plan.
 
-### Oracle: The Consultant
+### Sisyphus-Junior: The Specialist
 
-Read-only high-IQ consultant for architecture decisions and complex debugging. Consult Oracle when facing unfamiliar patterns, security concerns, or multi-system tradeoffs.
+When Sisyphus delegates a task via a specific **Category** (like `visual-engineering` or `deep`), **Sisyphus-Junior** is the agent that performs it. It is optimized for focused execution within a specific domain and cannot re-delegate, preventing infinite loops.
 
-### Supporting Cast
+### Specialist Subagents
 
+These agents are primarily designed to be called by other agents or for specific queries, rather than managing a full workflow.
+
+- **Oracle** — Read-only high-IQ consultant for architecture decisions and complex debugging.
+- **Librarian** — Documentation and OSS code search. Stays current on library APIs and best practices.
+- **Explore** — Fast codebase grep. Uses speed-focused models for pattern discovery.
+- **Multimodal Looker** — Vision and screenshot analysis.
 - **Metis** — Gap analyzer. Catches what Prometheus missed before plans are finalized.
 - **Momus** — Ruthless reviewer. Validates plans against clarity, verification, and context criteria.
-- **Explore** — Fast codebase grep. Uses speed-focused models for pattern discovery.
-- **Librarian** — Documentation and OSS code search. Stays current on library APIs and best practices.
-- **Multimodal Looker** — Vision and screenshot analysis.
 
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