Merge refreshed schema DSL into canonical tool outputs

# Conflicts:
#	docs/event-producer-consumer.md

packages/session-persistence/session-checkpoint-policy/tests/fixtures/crash-child.ts

@@ -0,0 +1,60 @@
+import { writeFile } from 'node:fs/promises'
+import { Context } from 'cordis'
+import AgentLoop from '@deepseek-ai/dsh-agent-loop'
+import { mountAgentLoopTestDependencies } from '@deepseek-ai/dsh-agent-loop-testkit'
+import { CallId, type GenerateOptions, LlmAdapter, type StreamChunk } from '@deepseek-ai/dsh-llm'
+import { SessionId } from '@deepseek-ai/dsh-session'
+import SessionPersistenceJsonl from '@deepseek-ai/dsh-session-persistence-jsonl'
+import * as checkpointPolicy from '../../src/index.ts'
+
+function waitForCrash(): Promise<never> {
+  return new Promise(() => { setInterval(() => {}, 60_000) })
+}
+
+const [mode, root, marker] = process.argv.slice(2)
+if ((mode !== 'request' && mode !== 'tool') || root === undefined || marker === undefined) {
+  throw new Error('usage: crash-child.ts <request|tool> <persistence-root> <marker>')
+}
+const persistenceRoot = root
+const failpoint = marker
+
+class CrashAdapter extends LlmAdapter {
+  async * stream(_options: GenerateOptions): AsyncIterable<StreamChunk> {
+    if (mode === 'request') {
+      await writeFile(failpoint, 'request-dispatched')
+      await waitForCrash()
+      return
+    }
+    yield { type: 'block-start', index: 0, blockType: 'tool-call' }
+    yield {
+      type: 'block-end',
+      index: 0,
+      block: { type: 'tool-call', id: CallId('crash-call'), name: 'crash_tool', arguments: '{}' },
+    }
+    yield { type: 'finish', reason: { kind: 'tool-calls' } }
+  }
+}
+
+const ctx = new Context()
+await mountAgentLoopTestDependencies(ctx)
+await ctx.plugin(AgentLoop, { agents: [] })
+await ctx.plugin(SessionPersistenceJsonl, { root: persistenceRoot, compression: 'none' })
+await ctx.plugin(checkpointPolicy)
+ctx.llm.registerAdapter(['crash'], new CrashAdapter())
+ctx.tools.register({
+  name: 'crash_tool',
+  description: 'records an external effect and never returns',
+  parameters: {},
+  output: { schema: { type: 'null' }, render: () => [] },
+  async execute() {
+    await writeFile(failpoint, 'tool-side-effect')
+    return waitForCrash()
+  },
+})
+
+const handle = await ctx.agents.create({
+  sessionId: SessionId('semantic-checkpoint-crash'),
+  agentOptions: { provider: 'crash', model: 'crash' },
+})
+handle.agent.send([{ type: 'text', text: 'exercise the crash boundary' }])
+await waitForCrash()