diff --git a/packages/core/tools/src/batch.ts b/packages/core/tools/src/batch.ts
index ea744a9d8b..d1b0e1a6f4 100644
--- a/packages/core/tools/src/batch.ts
+++ b/packages/core/tools/src/batch.ts
@@ -257,7 +257,11 @@ class BatchSettlement {
         message: createToolResultMessage({ callId: block.id, content: result.content, isError: result.isError }),
         ...result.error?.info ? { error: result.error.info } : {},
         ...result.meta !== undefined ? { meta: result.meta } : {},
-      }, { surfaceOp: 'append', ...callSeq === undefined ? {} : { sourceEventSeqs: [callSeq] } })
+      }, {
+        surfaceOp: 'append',
+        // oxlint-disable-next-line typescript/no-non-null-assertion -- start records a call seq whenever this batch logs results
+        sourceEventSeqs: [callSeq!],
+      })
     }
     this.results.push({ callId: block.id, result })
     this.contexts.push(...result.additionalContexts ?? [])
diff --git a/packages/core/tools/tests/tools.spec.ts b/packages/core/tools/tests/tools.spec.ts
index ca90e1bd72..7b12f80037 100644
--- a/packages/core/tools/tests/tools.spec.ts
+++ b/packages/core/tools/tests/tools.spec.ts
@@ -1,4 +1,5 @@
 import { executeToolFixture } from '@deepseek-ai/dsh-tool-testkit'
+import { ToolExecutionPipeline } from '@deepseek-ai/dsh-tools/pipeline'
 import * as NativeToolExecutor from '@deepseek-ai/dsh-tool-executor-native'
 import { describe, expect, expectTypeOf, it } from 'vitest'
 import { Context } from '@deepseek-ai/cordis'
@@ -1761,6 +1762,25 @@ describe('ToolRuntime', () => {
     expect(observed).toBe(1)
   })
 
+  it('reports cancellation before an executor refusal without entering policy', async ({ onTestFinished }) => {
+    const ctx = await setup()
+    onTestFinished(() => ctx.fiber.dispose())
+    let policyCalls = 0
+    ctx.on('tools/pre-execute', async (_exec, next) => { policyCalls += 1; return next() })
+    const pipeline = new ToolExecutionPipeline(ctx, {
+      get: () => echoTool,
+      reject: () => new Error('executor refuses direct calls'),
+    })
+    const prepared = await pipeline.prepare({
+      callId: ToolCallId('cancelled-refusal'), name: 'echo', arguments: {}, signal: AbortSignal.abort(),
+    })
+    expect(prepared.kind).toBe('final-result')
+    if (prepared.kind === 'dispatch') throw new Error('cancelled call was dispatched')
+    const result = await pipeline.complete(prepared.exec, prepared)
+    expect(result.error?.info?.code).toBe(TOOL_ABORTED_BEFORE_DISPATCH)
+    expect(policyCalls).toBe(0)
+  })
+
   it('a pre-execute deny short-circuits before tools/execute (the seam never runs)', async () => {
     const ctx = await setup()
     ctx.tools.register(echoTool)
diff --git a/packages/test-support/tool-testkit/package.json b/packages/test-support/tool-testkit/package.json
index eb3221b5f6..f0835ab2ea 100644
--- a/packages/test-support/tool-testkit/package.json
+++ b/packages/test-support/tool-testkit/package.json
@@ -34,6 +34,7 @@
   "devDependencies": {
     "@deepseek-ai/cordis": "workspace:~",
     "@deepseek-ai/dsh-llm": "workspace:*",
+    "@deepseek-ai/dsh-system-prompt": "workspace:*",
     "@deepseek-ai/dsh-tools": "workspace:*"
   }
 }
diff --git a/packages/test-support/tool-testkit/tests/model-call.spec.ts b/packages/test-support/tool-testkit/tests/model-call.spec.ts
new file mode 100644
index 0000000000..3638f83965
--- /dev/null
+++ b/packages/test-support/tool-testkit/tests/model-call.spec.ts
@@ -0,0 +1,41 @@
+/** Model-call fixtures preserve raw JSON input and reject incomplete execution. */
+import { Context } from '@deepseek-ai/cordis'
+import { ToolCallId } from '@deepseek-ai/dsh-llm'
+import SystemPrompt from '@deepseek-ai/dsh-system-prompt'
+import Tools, { type ToolExecutor } from '@deepseek-ai/dsh-tools'
+import { expect, it, onTestFinished } from 'vitest'
+import { executeModelToolFixture } from '../src/index.ts'
+
+async function setup(execute: ToolExecutor['execute']): Promise<Context> {
+  const ctx = new Context()
+  onTestFinished(() => ctx.fiber.dispose())
+  await ctx.plugin(SystemPrompt)
+  await ctx.plugin(Tools)
+  ctx.tools.setExecutor({ describe: () => ({ schemas: [], knownNames: [] }), execute })
+  return ctx
+}
+
+const call = { callId: ToolCallId('fixture'), name: 'echo', signal: new AbortController().signal }
+
+it('serializes model arguments and returns the selected executor result without an Agent', async () => {
+  const result = { isError: false as const, value: 'done', content: [{ type: 'text' as const, text: 'done' }] }
+  const ctx = await setup(async (input) => {
+    expect(input.calls).toEqual([{ type: 'tool-call', id: call.callId, name: 'echo', arguments: '{"text":"hello"}' }])
+    expect(input.signal).toBe(call.signal)
+    expect(input.agent).toBeUndefined()
+    return { results: [{ callId: call.callId, result }], additionalContexts: [], concluded: false }
+  })
+  expect(await executeModelToolFixture(ctx, { ...call, arguments: { text: 'hello' } })).toBe(result)
+})
+
+it('rejects unencodable model arguments before invoking the executor', async () => {
+  const ctx = await setup(async () => { throw new Error('executor must not run') })
+  await expect(executeModelToolFixture(ctx, { ...call, arguments: undefined }))
+    .rejects.toThrow('Model tool fixture arguments must encode as JSON')
+})
+
+it('reports when an executor omits the requested result', async () => {
+  const ctx = await setup(async () => ({ results: [], additionalContexts: [], concluded: false }))
+  await expect(executeModelToolFixture(ctx, { ...call, arguments: {} }))
+    .rejects.toThrow('Executor omitted the model tool fixture result')
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index ea116afa03..8913024452 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -15481,6 +15481,9 @@ importers:
       '@deepseek-ai/dsh-llm':
         specifier: workspace:*
         version: link:../../llm/llm
+      '@deepseek-ai/dsh-system-prompt':
+        specifier: workspace:*
+        version: link:../../core/system-prompt
       '@deepseek-ai/dsh-tools':
         specifier: workspace:*
         version: link:../../core/tools