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, 40 insertions, 0 deletions

diff --git a/cc/04-schema-debug.md b/cc/04-schema-debug.md
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+# Schema Debug — What zodToJsonSchema Actually Produces
+
+Run this to see what the AI SDK actually sends to Anthropic:
+
+```bash
+node --experimental-strip-types -e "
+import { z } from 'zod';
+import { zodToJsonSchema } from 'zod-to-json-schema';
+
+const schema = z.object({
+    path: z.string().describe('Path to the file, relative to the working directory'),
+    offset: z.number().int().min(1).optional().describe('1-indexed start line. Default: 1.'),
+    limit: z.number().int().min(1).optional().describe('Max lines to return. Default: 500. Hard cap: 5000.'),
+});
+
+console.log(JSON.stringify(zodToJsonSchema(schema), null, 2));
+"
+```
+
+## Check the @ai-sdk/anthropic adapter's tool serialization
+
+```bash
+grep -n 'input_schema\|tools\|jsonSchema\|convertTools' node_modules/@ai-sdk/anthropic/dist/index.mjs | head -30
+```
+
+## Check if streamText is receiving the tools correctly
+
+Look at how streamText processes tool options in the AI SDK:
+
+```bash
+grep -n 'tools\|toolChoice\|toolCall' node_modules/ai/dist/index.mjs | head -40
+```
+
+## Key questions to answer
+
+1. Does `zodToJsonSchema` output `$schema`? If yes, Anthropic may silently reject the tool definition.
+2. Does it output `additionalProperties`? Same concern.
+3. Does the `@ai-sdk/anthropic` adapter strip these before sending to the API?
+4. Does the adapter forward parameter `description` fields from JSON Schema to Anthropic's wire format?
+5. Is `tool_choice` being set or defaulting to something suboptimal?