fix(core): normalize tool schemas for Anthropic, add toolChoice=auto; feat(summon): agent definition support; docs: cc/ research findings

- registry.ts: add normalizeForAnthropic() to strip , additionalProperties, default, nullable from zodToJsonSchema output so Anthropic doesn't silently reject tool definitions
- agent.ts: add toolChoice=auto for Claude OAuth to prevent Opus thinking forever without calling tools
- summon.ts: add agentSlug parameter, build agents catalog in description, add toAvailableAgents helper
- agent-manager.ts: wire agent definition loading into spawnChildAgent, agent model fallback
- loader.ts: export loadAgent, expandAgentToolNames, getAgentDirPaths; add getAgentDirPaths for permission gate
- agent.ts: auto-allow read-only tools in agent definition directories
- packaging/PKGBUILD: exclude ARM64 prebuilds from x86_64 package
- cc/: research findings on Claude Opus tool calling issues
- tests: loader tests, summon tool tests

1 files changed, 38 insertions, 0 deletions

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+# Claude Opus Tool Calling Investigation
+
+## Problem
+Claude Opus "thinks forever" and doesn't call tools when used outside Claude Code's harness (in Dispatch's own agent harness).
+
+## Summary of Findings
+
+### 1. Tool Schema Format
+Dispatch uses the AI SDK v6 (`@ai-sdk/anthropic@^3.x`) which should handle format conversion automatically. However, `zodToJsonSchema()` produces Draft 7 JSON Schema with fields (`$schema`, `additionalProperties`, `default`) that Anthropic's API doesn't support. Dispatch does **no schema normalization**.
+
+### 2. Anthropic's requirements
+Anthropic's `input_schema` must be clean JSON Schema:
+- Root `type: "object"` is mandatory
+- No `$schema`, `additionalProperties`, `default`, `nullable`
+- No combiners (`anyOf`, `oneOf`, etc.)
+- Parameter `description` fields are strongly recommended
+
+### 3. Missing tool_choice
+Dispatch doesn't set `tool_choice` in `streamText()` options. The default may cause Opus to not call tools.
+
+### 4. System prompt
+The system prompt tells Opus what tools exist but may not be forceful enough about actually USING them instead of just talking about solutions.
+
+### 5. No Anthropic-specific schema normalization
+Unlike opencode's `normalizeSchemaForCCA()`, dispatch passes raw JSON Schema to the AI SDK without stripping unsupported fields.
+
+## Key Files
+
+| File | Purpose |
+|------|---------|
+| `packages/core/src/tools/registry.ts` | Tool → AI SDK conversion |
+| `packages/core/src/agent/agent.ts` | Agent loop, `streamText({tools})` |
+| `packages/api/src/agent-manager.ts` | Provides tool config to agent |
+| `packages/core/src/llm/provider.ts` | Provider creation |
+
+## Next Steps
+
+See `03-recommendations.md` for specific fixes to try.