Add "Change V5.4.0: Multi-Model Agent Support Proposal"

Change V5.4.0%3A Multi-Model Agent Support Proposal.-.md

@@ -0,0 +1,97 @@
+# Change V5.4.0: Multi-Model Agent Support
+
+**Type:** Feature
+**Version:** 5.4.0
+**Status:** Proposed
+**Date:** 2026-01-28
+
+## Summary
+
+Add model selection capability to the plugin system, allowing agents to specify preferred Claude models (opus, sonnet, haiku) with inheritance and backward compatibility.
+
+## Motivation
+
+Different agent tasks have different complexity requirements:
+- **Architecture decisions** need deep reasoning (Opus)
+- **Implementation work** needs balanced capability (Sonnet)
+- **Simple validation** needs speed and cost efficiency (Haiku)
+
+Currently all agents use the session's default model with no way to optimize.
+
+## Proposed Changes
+
+### 1. Agent Frontmatter Extension
+
+Add optional `model` field to agent YAML frontmatter:
+
+```yaml
+---
+name: planner
+description: Sprint planning agent
+model: opus  # NEW: opus | sonnet | haiku
+---
+```
+
+### 2. Plugin Default Model
+
+Add optional `defaultModel` to plugin.json:
+
+```json
+{
+  "name": "projman",
+  "defaultModel": "sonnet"
+}
+```
+
+### 3. Inheritance Chain
+
+```
+Agent model (highest priority)
+    ↓ if not set
+Plugin defaultModel
+    ↓ if not set
+System default: sonnet
+```
+
+## Model Allocation Strategy
+
+| Model | Use For | Cost | Speed |
+|-------|---------|------|-------|
+| **Opus** | Architecture, security analysis, complex reasoning | Highest | Slower |
+| **Sonnet** | Implementation, coordination, standard tasks | Medium | Balanced |
+| **Haiku** | Simple validation, quick checks | Lowest | Fastest |
+
+### Recommended Agent Assignments
+
+| Plugin | Agent | Model | Rationale |
+|--------|-------|-------|-----------|
+| projman | planner | opus | Architecture decisions |
+| projman | orchestrator | sonnet | Coordination |
+| projman | executor | sonnet | Implementation |
+| projman | code-reviewer | opus | Quality review |
+| pr-review | security-reviewer | opus | Security analysis |
+| code-sentinel | security-reviewer | opus | Security scanning |
+| data-platform | data-analysis | opus | Complex analysis |
+| viz-platform | component-check | haiku | Simple validation |
+| contract-validator | agent-check | haiku | Quick verification |
+
+## Backward Compatibility
+
+- Agents without `model` field continue working (use defaults)
+- Plugins without `defaultModel` use system default
+- All changes are additive - no breaking changes
+
+## Implementation Sprints
+
+- **Sprint 7:** Core implementation (this proposal)
+
+## Files Affected
+
+- 7 agent files (model field additions)
+- 6 plugin.json files (defaultModel additions)
+- 3 documentation files
+- 1 validation script
+
+---
+
+**Tags:** feature, agents, model-selection, v5.4.0