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feat(system-prompt): cache dynamic policy context

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This commit is contained in:
NI0317
2026-07-30 22:09:15 +08:00
parent 936a487bb0
commit 8b4cbe4293
45 changed files with 722 additions and 374 deletions
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36
packages/core/agent-loop/src/agent.ts
View File

@@ -34,6 +34,7 @@ import {
LlmError,
assertNever,
createAssistantMessage,
createUserMessage,
deepFreeze,
errorChain,
freezeMessage,
@@ -45,7 +46,7 @@ import {
import type { GenerateOptions, LlmCallConfig, LlmFailure, Message, PreparedLlmCall, ResolvedRetryPolicy } from '@deepseek-ai/dsh-llm'
import { canonicalHeader, headerEquals } from '@deepseek-ai/dsh-session'
import type { AssistantMessage, Session, SessionId, TurnEndReason, TurnTrigger, UserMessage } from '@deepseek-ai/dsh-session'
import { renderPrompt } from '@deepseek-ai/dsh-system-prompt'
import { renderContextSnapshot, renderPrompt } from '@deepseek-ai/dsh-system-prompt'
import type {} from '@deepseek-ai/dsh-tools'
import { executeToolCalls } from './tool-calls.ts'
@@ -54,6 +55,34 @@ type StepOutcome =
| { kind: 'completed'; continueTurn: boolean; concluded: boolean; maxTokens: boolean }
| { kind: 'request-failed'; error: RequestError; failure: LlmFailure; retryPolicy: ResolvedRetryPolicy | undefined }
const RUNTIME_CONTEXT_SOURCE = '@deepseek-ai/dsh-system-prompt'
const CLEARED_RUNTIME_CONTEXT = 'Current runtime context: none. Earlier runtime-context snapshots no longer apply.'
/** Latest retained cache-safe runtime-context snapshot, excluding compacted-away history. */
function retainedRuntimeContext(session: Session): string | undefined {
for (const message of [...session.deriveMessages()].reverse()) {
if (message.role !== 'user'
|| message.source.kind !== 'plugin'
|| message.source.plugin !== RUNTIME_CONTEXT_SOURCE) continue
const [block] = message.content
if (message.content.length === 1 && block?.type === 'text') return block.text
return undefined
}
return undefined
}
/** Append a full current snapshot only when it changed or compaction removed it. */
function materializeRuntimeContext(session: Session, current: string): void {
const previous = retainedRuntimeContext(session)
if (previous === undefined && current.length === 0) return
const snapshot = current.length === 0 ? CLEARED_RUNTIME_CONTEXT : current
if (previous === snapshot) return
session.append('user/message', createUserMessage({
content: [{ type: 'text', text: snapshot }],
source: { kind: 'plugin', plugin: RUNTIME_CONTEXT_SOURCE },
}), { surfaceOp: 'append' })
}
/**
* The concrete {@link Agent}: each `run()` owns one turn and repeats model
* steps while tools or steering require another request.
@@ -511,10 +540,13 @@ export class ReactLoopAgent implements Agent {
// this request together.
this.drainOutbox(turn)
// Assemble the system prompt fresh each step (it may depend on log state).
// Assemble request-owned prompt inputs fresh each step. Dynamic context is
// committed at the tail before deriving history, preserving the stable
// system/history cache prefix while keeping every model-visible byte logged.
const assembly = await this.loopCtx.systemPrompt.assemble(assembleContextFor(this, signal))
signal.throwIfAborted()
const system = renderPrompt(assembly)
materializeRuntimeContext(session, renderContextSnapshot(assembly))
// Snapshot the exact log prefix: the reconstruction boundary. Appends
// after this synchronous snapshot join the next request.

118
packages/core/agent-loop/tests/loop.spec.ts
View File

@@ -254,7 +254,7 @@ describe('agent loop', () => {
// NO system field at all (not an empty string).
const adapter = new MockAdapter([textResponse('ok')])
const ctx = await harness(adapter)
ctx.on('system-prompt/assemble', async () => ({ sections: [], tools: [], variables: {} }))
ctx.on('system-prompt/assemble', async () => ({ sections: [], contexts: [], tools: [], variables: {} }))
const agent = ctx.agentLoop.create(SessionId('a-no-system'), { provider: 'mock', model: 'mock' })
send(agent, 'hi')
@@ -264,6 +264,122 @@ describe('agent loop', () => {
expect('system' in adapter.requests[0]!).toBe(false)
})
it('materializes changed runtime context at the history tail without rewriting the system header', async () => {
const adapter = new MockAdapter([
textResponse('one'),
textResponse('two'),
textResponse('three'),
textResponse('four'),
textResponse('five'),
])
const ctx = await harness(adapter)
let mode = 'read-only'
const dispose = ctx.systemPrompt.context({ name: 'policy', order: 0, text: () => `Mode: ${mode}.` })
const agent = ctx.agentLoop.create(SessionId('a-runtime-context'), { provider: 'mock', model: 'mock' })
const contextEvents = () => agent.session.events.flatMap(event =>
event.type === 'user/message'
&& event.data.source.kind === 'plugin'
&& event.data.source.plugin === '@deepseek-ai/dsh-system-prompt'
? [event]
: [])
send(agent, 'first')
await waitForIdle(ctx, agent)
expect(contextEvents()).toHaveLength(1)
expect(contextEvents()[0]?.data.content).toEqual([{
type: 'text',
text: 'Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nMode: read-only.',
}])
send(agent, 'unchanged')
await waitForIdle(ctx, agent)
expect(contextEvents()).toHaveLength(1)
mode = 'danger-full-access'
send(agent, 'changed')
await waitForIdle(ctx, agent)
expect(contextEvents()).toHaveLength(2)
const changedBlock = contextEvents()[1]?.data.content[0]
expect(changedBlock?.type).toBe('text')
if (changedBlock?.type !== 'text') throw new Error('changed runtime context is not text')
expect(changedBlock.text).toContain('danger-full-access')
dispose()
send(agent, 'cleared')
await waitForIdle(ctx, agent)
expect(contextEvents()).toHaveLength(3)
expect(contextEvents()[2]?.data.content).toEqual([{
type: 'text',
text: 'Current runtime context: none. Earlier runtime-context snapshots no longer apply.',
}])
send(agent, 'still clear')
await waitForIdle(ctx, agent)
expect(contextEvents()).toHaveLength(3)
expect(adapter.requests.map(request => request.system)).toEqual(Array(5).fill(adapter.requests[0]?.system))
expect(agent.session.events.filter(event => event.type === 'request/header')).toHaveLength(1)
})
it('re-emits unchanged runtime context when a surface replacement removed the retained snapshot', async () => {
const adapter = new MockAdapter([textResponse('one'), textResponse('two')])
const ctx = await harness(adapter)
ctx.systemPrompt.context({ name: 'policy', order: 0, text: 'Mode: read-only.' })
const agent = ctx.agentLoop.create(SessionId('a-runtime-context-compacted'), { provider: 'mock', model: 'mock' })
send(agent, 'first')
await waitForIdle(ctx, agent)
const contextEvent = agent.session.events.find(event =>
event.type === 'user/message'
&& event.data.source.kind === 'plugin'
&& event.data.source.plugin === '@deepseek-ai/dsh-system-prompt')
if (contextEvent?.type !== 'user/message') throw new Error('first turn did not materialize runtime context')
agent.session.append('user/message', createUserMessage({
content: [{ type: 'text', text: 'compacted summary' }],
source: { kind: 'plugin', plugin: 'test-compaction' },
}), {
surfaceOp: { op: 'replace', start: contextEvent.seq, end: contextEvent.seq },
sourceEventSeqs: [contextEvent.seq],
})
send(agent, 'after compaction')
await waitForIdle(ctx, agent)
const runtimeContexts = agent.session.events.flatMap(event =>
event.type === 'user/message'
&& event.data.source.kind === 'plugin'
&& event.data.source.plugin === '@deepseek-ai/dsh-system-prompt'
? [event]
: [])
expect(runtimeContexts).toHaveLength(2)
expect(adapter.requests[1]?.messages.some(message =>
message.source.kind === 'plugin'
&& message.source.plugin === '@deepseek-ai/dsh-system-prompt')).toBe(true)
})
it('replaces a malformed retained runtime-context message with the current complete snapshot', async () => {
const adapter = new MockAdapter([textResponse('ok')])
const ctx = await harness(adapter)
ctx.systemPrompt.context({ name: 'policy', order: 0, text: 'Mode: read-only.' })
const agent = ctx.agentLoop.create(SessionId('a-runtime-context-malformed'), { provider: 'mock', model: 'mock' })
agent.session.append('user/message', createUserMessage({
content: [{ type: 'text', text: 'broken' }, { type: 'text', text: 'snapshot' }],
source: { kind: 'plugin', plugin: '@deepseek-ai/dsh-system-prompt' },
}), { surfaceOp: 'append' })
send(agent, 'repair context')
await waitForIdle(ctx, agent)
const runtimeContexts = agent.session.events.flatMap(event =>
event.type === 'user/message'
&& event.data.source.kind === 'plugin'
&& event.data.source.plugin === '@deepseek-ai/dsh-system-prompt'
? [event]
: [])
expect(runtimeContexts).toHaveLength(2)
expect(runtimeContexts[1]?.data.content).toEqual([{
type: 'text',
text: 'Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nMode: read-only.',
}])
})
it('records raw chunks for replay as assistant/chunk session events', async () => {
const adapter = new MockAdapter([textResponse('abc')])
const ctx = await harness(adapter)