feat(orch): add multi-model consensus skill

Enables agents to query multiple AI models for:
- Second opinions on reasoning
- Architectural decisions
- Devil's advocate analysis
- Brainstorming and critique

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.beads/issues.jsonl

@@ -1,3 +1,4 @@
+{"id":"skills-25l","title":"Create orch skill for multi-model consensus","description":"Build a skill that exposes orch CLI capabilities to agents for querying multiple AI models","status":"closed","priority":2,"issue_type":"feature","created_at":"2025-11-30T15:43:49.209528963-08:00","updated_at":"2025-11-30T15:47:36.608887453-08:00","closed_at":"2025-11-30T15:47:36.608887453-08:00"}
 {"id":"skills-2xo","title":"Add README.md for web-search skill","description":"web-search skill has SKILL.md and scripts but no README.md. AGENTS.md says README.md is for humans, contains installation instructions, usage examples, prerequisites.","status":"open","priority":2,"issue_type":"task","created_at":"2025-11-30T11:58:14.26066025-08:00","updated_at":"2025-11-30T12:00:25.561281052-08:00","dependencies":[{"issue_id":"skills-2xo","depends_on_id":"skills-vb5","type":"blocks","created_at":"2025-11-30T12:01:30.240439018-08:00","created_by":"daemon"}]}
 {"id":"skills-39g","title":"RFC: .skills manifest pattern for per-repo skill deployment","description":"Document the .skills file pattern where projects declare skills in a manifest, .envrc reads it, and agents can query/edit it.","status":"closed","priority":2,"issue_type":"feature","created_at":"2025-11-30T12:37:50.106992381-08:00","updated_at":"2025-11-30T12:43:04.155161727-08:00","closed_at":"2025-11-30T12:43:04.155161727-08:00"}
 {"id":"skills-3o7","title":"Fix ai-skills.nix missing sha256 hash","description":"modules/ai-skills.nix:16 has empty sha256 placeholder for opencode-skills npm package. Either get actual hash or remove/comment out the incomplete fetchFromNpm approach.","status":"closed","priority":2,"issue_type":"bug","created_at":"2025-11-30T11:58:24.404929863-08:00","updated_at":"2025-11-30T12:12:39.372107348-08:00","closed_at":"2025-11-30T12:12:39.372107348-08:00"}

flake.nix

@@ -14,6 +14,7 @@
       # List of available skills
       availableSkills = [
         "niri-window-capture"
+        "orch"
         "screenshot-latest"
         "tufte-press"
         "worklog"

skills/orch/README.md

@@ -0,0 +1,45 @@
+# Orch Skill
+
+Multi-model AI consensus skill for Claude Code and OpenCode agents.
+
+## Purpose
+
+Enables agents to query multiple AI models simultaneously and aggregate their perspectives for:
+- Second opinions on reasoning
+- Architectural/design decisions
+- Devil's advocate analysis
+- Brainstorming from diverse viewpoints
+- Code review with multiple perspectives
+
+## Quick Start
+
+```bash
+# Get consensus on a decision
+orch consensus "Should we use SQLite or PostgreSQL for this use case?" flash gemini claude
+
+# Devil's advocate
+orch consensus "Should we adopt microservices?" gpt5:for claude:against flash:neutral
+
+# Code review with file context
+orch consensus "Is this approach correct?" flash gemini --file src/handler.py --mode critique
+```
+
+## Files
+
+- `SKILL.md` - Agent instructions and usage patterns (loaded by Claude Code)
+- `README.md` - Human documentation (this file)
+
+## Prerequisites
+
+- `orch` CLI from ~/proj/orch
+- API keys for llm library providers
+
+## Installation
+
+Add `orch` to your project's `.skills` file:
+
+```
+orch
+```
+
+Then run `direnv reload`.

skills/orch/SKILL.md

@@ -0,0 +1,137 @@
+---
+name: orch
+description: Query multiple AI models for consensus decisions, second opinions, and devil's advocate analysis using the orch CLI.
+---
+
+# Orch - Multi-Model Consensus Skill
+
+Query multiple AI models simultaneously and aggregate their perspectives. Use this when you need:
+- A second opinion on your reasoning
+- Multiple perspectives on a decision
+- Devil's advocate analysis
+- Brainstorming from diverse viewpoints
+
+## When to Use
+
+Invoke this skill when:
+- Making architectural or design decisions ("Should we use X or Y?")
+- Reviewing your own proposed solution before presenting to user
+- The user asks for multiple AI perspectives
+- You want to stress-test an approach with opposing viewpoints
+- Complex tradeoffs where different perspectives would help
+
+## Commands
+
+### orch consensus
+
+Query multiple models for their verdict on a question.
+
+```bash
+orch consensus "PROMPT" MODEL1 MODEL2 [MODEL3...]
+```
+
+**Model Aliases** (use these):
+- `flash` → gemini-2.5-flash (fast, cheap)
+- `gemini` → gemini-3-pro-preview (strong reasoning)
+- `claude` → claude-sonnet-4.5 (balanced)
+- `haiku` → claude-haiku-4.5 (fast, cheap)
+- `opus` → claude-opus-4.1 (strongest)
+- `gpt` / `gpt5` → gpt-5 (strong reasoning)
+- `gpt4` → gpt-4o (legacy)
+
+**Options**:
+- `--mode vote` (default) - Models give Support/Oppose/Neutral verdict
+- `--mode brainstorm` - Generate ideas without judgment
+- `--mode critique` - Find flaws and weaknesses
+- `--mode open` - Freeform responses, no structured output
+- `--temperature 0.1` - Lower = more focused (default 0.1)
+- `--file PATH` - Include file as context
+- `--enhance` - Use AI to improve prompt before querying
+
+**Stances** (devil's advocate):
+Append `:for`, `:against`, or `:neutral` to bias a model's perspective:
+```bash
+orch consensus "Should we rewrite in Rust?" gpt5:for claude:against gemini:neutral
+```
+
+### orch chat
+
+Single-model conversation (when you don't need consensus):
+```bash
+orch chat "MESSAGE" --model gemini
+```
+
+## Usage Patterns
+
+### Quick Second Opinion
+When you've reasoned through something and want validation:
+```bash
+orch consensus "I think we should use SQLite for this because [reasons]. Is this sound?" flash gemini
+```
+
+### Architecture Decision
+When facing a tradeoff:
+```bash
+orch consensus "Microservices vs monolith for a 3-person team building an e-commerce site?" flash gemini claude --mode vote
+```
+
+### Code Review
+Include the code as context:
+```bash
+orch consensus "Is this error handling approach correct and complete?" flash gemini --file src/handler.py
+```
+
+### Devil's Advocate
+Get opposing viewpoints deliberately:
+```bash
+orch consensus "Should we adopt Kubernetes?" gpt5:for claude:against flash:neutral
+```
+
+### Brainstorm
+Generate diverse ideas:
+```bash
+orch consensus "How could we improve the CI/CD pipeline?" flash gemini claude --mode brainstorm
+```
+
+### Critique Your Work
+Find weaknesses before presenting:
+```bash
+orch consensus "What are the flaws in this API design?" flash gemini --file api-spec.yaml --mode critique
+```
+
+## Output Format
+
+Vote mode returns structured verdicts:
+```
+┌─────────────────────────────────────────────────────────────┐
+│                      CONSENSUS: MIXED                        │
+│                   SUPPORT: 2  OPPOSE: 1  NEUTRAL: 0          │
+└─────────────────────────────────────────────────────────────┘
+
+[flash] gemini-2.5-flash - SUPPORT
+Reasoning: ...
+
+[gemini] gemini-3-pro-preview - SUPPORT
+Reasoning: ...
+
+[claude] claude-sonnet-4.5 - OPPOSE
+Reasoning: ...
+```
+
+## Guidelines
+
+1. **Use for genuine uncertainty** - Don't use orch for trivial decisions or to avoid thinking
+2. **Provide context** - Better prompts get better consensus; use `--file` when relevant
+3. **Choose models wisely** - flash/haiku for quick checks, opus/gpt5 for complex reasoning
+4. **Consider stances** - Devil's advocate is powerful for stress-testing ideas
+5. **Parse the reasoning** - The verdict matters less than understanding the reasoning
+
+## Requirements
+
+- `orch` CLI installed and in PATH (from ~/proj/orch)
+- API keys configured for llm library (ANTHROPIC_API_KEY, GOOGLE_API_KEY, OPENAI_API_KEY)
+- Run via: `cd ~/proj/orch && uv run orch ...` if not globally installed
+
+## Examples
+
+See `examples/` directory for sample outputs from different consensus modes.