Simplify compaction: remove proactive abort, use Agent.continue() for retry

- Add agentLoopContinue() to pi-ai for resuming from existing context
- Add Agent.continue() method and transport.continue() interface
- Simplify AgentSession compaction to two cases: overflow (auto-retry) and threshold (no retry)
- Remove proactive mid-turn compaction abort
- Merge turn prefix summary into main summary
- Add isCompacting property to AgentSession and RPC state
- Block input during compaction in interactive mode
- Show compaction count on session resume
- Rename RPC.md to rpc.md for consistency

Related to #128
This commit is contained in:
Mario Zechner 2025-12-09 21:43:49 +01:00
parent d67c69c6e9
commit 5a9d844f9a
27 changed files with 1261 additions and 1011 deletions

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@ -2,6 +2,10 @@
## [Unreleased]
### Added
- **`agentLoopContinue` function**: Continue an agent loop from existing context without adding a new user message. Validates that the last message is `user` or `toolResult`. Useful for retry after context overflow or resuming from manually-added tool results.
### Breaking Changes
- Removed provider-level tool argument validation. Validation now happens in `agentLoop` via `executeToolCalls`, allowing models to retry on validation errors. For manual tool execution, use `validateToolCall(tools, toolCall)` or `validateToolArguments(tool, toolCall)`.

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@ -898,6 +898,34 @@ const messages = await stream.result();
context.messages.push(...messages);
```
### Continuing from Existing Context
Use `agentLoopContinue` to resume an agent loop without adding a new user message. This is useful for:
- Retrying after context overflow (after compaction reduces context size)
- Resuming from tool results that were added manually to the context
```typescript
import { agentLoopContinue, AgentContext } from '@mariozechner/pi-ai';
// Context already has messages - last must be 'user' or 'toolResult'
const context: AgentContext = {
systemPrompt: 'You are helpful.',
messages: [userMessage, assistantMessage, toolResult],
tools: [myTool]
};
// Continue processing from the tool result
const stream = agentLoopContinue(context, { model });
for await (const event of stream) {
// Same events as agentLoop, but no user message events emitted
}
const newMessages = await stream.result();
```
**Validation**: Throws if context has no messages or if the last message is an assistant message.
### Defining Tools with TypeBox
Tools use TypeBox schemas for runtime validation and type inference:

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@ -4,7 +4,10 @@ import { EventStream } from "../utils/event-stream.js";
import { validateToolArguments } from "../utils/validation.js";
import type { AgentContext, AgentEvent, AgentLoopConfig, AgentTool, AgentToolResult, QueuedMessage } from "./types.js";
// Main prompt function - returns a stream of events
/**
* Start an agent loop with a new user message.
* The prompt is added to the context and events are emitted for it.
*/
export function agentLoop(
prompt: UserMessage,
context: AgentContext,
@ -12,92 +15,137 @@ export function agentLoop(
signal?: AbortSignal,
streamFn?: typeof streamSimple,
): EventStream<AgentEvent, AgentContext["messages"]> {
const stream = new EventStream<AgentEvent, AgentContext["messages"]>(
(event: AgentEvent) => event.type === "agent_end",
(event: AgentEvent) => (event.type === "agent_end" ? event.messages : []),
);
const stream = createAgentStream();
// Run the prompt async
(async () => {
// Track new messages generated during this prompt
const newMessages: AgentContext["messages"] = [];
// Create user message for the prompt
const messages = [...context.messages, prompt];
newMessages.push(prompt);
const newMessages: AgentContext["messages"] = [prompt];
const currentContext: AgentContext = {
...context,
messages: [...context.messages, prompt],
};
stream.push({ type: "agent_start" });
stream.push({ type: "turn_start" });
stream.push({ type: "message_start", message: prompt });
stream.push({ type: "message_end", message: prompt });
// Update context with new messages
const currentContext: AgentContext = {
...context,
messages,
};
// Keep looping while we have tool calls or queued messages
let hasMoreToolCalls = true;
let firstTurn = true;
let queuedMessages: QueuedMessage<any>[] = (await config.getQueuedMessages?.()) || [];
while (hasMoreToolCalls || queuedMessages.length > 0) {
if (!firstTurn) {
stream.push({ type: "turn_start" });
} else {
firstTurn = false;
}
// Process queued messages first (inject before next assistant response)
if (queuedMessages.length > 0) {
for (const { original, llm } of queuedMessages) {
stream.push({ type: "message_start", message: original });
stream.push({ type: "message_end", message: original });
if (llm) {
currentContext.messages.push(llm);
newMessages.push(llm);
}
}
queuedMessages = [];
}
// console.log("agent-loop: ", [...currentContext.messages]);
// Stream assistant response
const message = await streamAssistantResponse(currentContext, config, signal, stream, streamFn);
newMessages.push(message);
if (message.stopReason === "error" || message.stopReason === "aborted") {
// Stop the loop on error or abort
stream.push({ type: "turn_end", message, toolResults: [] });
stream.push({ type: "agent_end", messages: newMessages });
stream.end(newMessages);
return;
}
// Check for tool calls
const toolCalls = message.content.filter((c) => c.type === "toolCall");
hasMoreToolCalls = toolCalls.length > 0;
const toolResults: ToolResultMessage[] = [];
if (hasMoreToolCalls) {
// Execute tool calls
toolResults.push(...(await executeToolCalls(currentContext.tools, message, signal, stream)));
currentContext.messages.push(...toolResults);
newMessages.push(...toolResults);
}
stream.push({ type: "turn_end", message, toolResults: toolResults });
// Get queued messages after turn completes
queuedMessages = (await config.getQueuedMessages?.()) || [];
}
stream.push({ type: "agent_end", messages: newMessages });
stream.end(newMessages);
await runLoop(currentContext, newMessages, config, signal, stream, streamFn);
})();
return stream;
}
/**
* Continue an agent loop from the current context without adding a new message.
* Used for retry after overflow - context already has user message or tool results.
* Throws if the last message is not a user message or tool result.
*/
export function agentLoopContinue(
context: AgentContext,
config: AgentLoopConfig,
signal?: AbortSignal,
streamFn?: typeof streamSimple,
): EventStream<AgentEvent, AgentContext["messages"]> {
// Validate that we can continue from this context
const lastMessage = context.messages[context.messages.length - 1];
if (!lastMessage) {
throw new Error("Cannot continue: no messages in context");
}
if (lastMessage.role !== "user" && lastMessage.role !== "toolResult") {
throw new Error(`Cannot continue from message role: ${lastMessage.role}. Expected 'user' or 'toolResult'.`);
}
const stream = createAgentStream();
(async () => {
const newMessages: AgentContext["messages"] = [];
const currentContext: AgentContext = { ...context };
stream.push({ type: "agent_start" });
stream.push({ type: "turn_start" });
// No user message events - we're continuing from existing context
await runLoop(currentContext, newMessages, config, signal, stream, streamFn);
})();
return stream;
}
function createAgentStream(): EventStream<AgentEvent, AgentContext["messages"]> {
return new EventStream<AgentEvent, AgentContext["messages"]>(
(event: AgentEvent) => event.type === "agent_end",
(event: AgentEvent) => (event.type === "agent_end" ? event.messages : []),
);
}
/**
* Shared loop logic for both agentLoop and agentLoopContinue.
*/
async function runLoop(
currentContext: AgentContext,
newMessages: AgentContext["messages"],
config: AgentLoopConfig,
signal: AbortSignal | undefined,
stream: EventStream<AgentEvent, AgentContext["messages"]>,
streamFn?: typeof streamSimple,
): Promise<void> {
let hasMoreToolCalls = true;
let firstTurn = true;
let queuedMessages: QueuedMessage<any>[] = (await config.getQueuedMessages?.()) || [];
while (hasMoreToolCalls || queuedMessages.length > 0) {
if (!firstTurn) {
stream.push({ type: "turn_start" });
} else {
firstTurn = false;
}
// Process queued messages first (inject before next assistant response)
if (queuedMessages.length > 0) {
for (const { original, llm } of queuedMessages) {
stream.push({ type: "message_start", message: original });
stream.push({ type: "message_end", message: original });
if (llm) {
currentContext.messages.push(llm);
newMessages.push(llm);
}
}
queuedMessages = [];
}
// Stream assistant response
const message = await streamAssistantResponse(currentContext, config, signal, stream, streamFn);
newMessages.push(message);
if (message.stopReason === "error" || message.stopReason === "aborted") {
// Stop the loop on error or abort
stream.push({ type: "turn_end", message, toolResults: [] });
stream.push({ type: "agent_end", messages: newMessages });
stream.end(newMessages);
return;
}
// Check for tool calls
const toolCalls = message.content.filter((c) => c.type === "toolCall");
hasMoreToolCalls = toolCalls.length > 0;
const toolResults: ToolResultMessage[] = [];
if (hasMoreToolCalls) {
// Execute tool calls
toolResults.push(...(await executeToolCalls(currentContext.tools, message, signal, stream)));
currentContext.messages.push(...toolResults);
newMessages.push(...toolResults);
}
stream.push({ type: "turn_end", message, toolResults: toolResults });
// Get queued messages after turn completes
queuedMessages = (await config.getQueuedMessages?.()) || [];
}
stream.push({ type: "agent_end", messages: newMessages });
stream.end(newMessages);
}
// Helper functions
async function streamAssistantResponse(
context: AgentContext,

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@ -1,3 +1,3 @@
export { agentLoop } from "./agent-loop.js";
export { agentLoop, agentLoopContinue } from "./agent-loop.js";
export * from "./tools/index.js";
export type { AgentContext, AgentEvent, AgentLoopConfig, AgentTool, QueuedMessage } from "./types.js";

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@ -3275,13 +3275,13 @@ export const MODELS = {
reasoning: true,
input: ["text"],
cost: {
input: 0.19999999999999998,
output: 0.7999999999999999,
input: 0.15,
output: 0.75,
cacheRead: 0,
cacheWrite: 0,
},
contextWindow: 163840,
maxTokens: 163840,
contextWindow: 8192,
maxTokens: 7168,
} satisfies Model<"openai-completions">,
"openai/gpt-4o-audio-preview": {
id: "openai/gpt-4o-audio-preview",
@ -4516,8 +4516,8 @@ export const MODELS = {
reasoning: false,
input: ["text", "image"],
cost: {
input: 0.049999999999999996,
output: 0.22,
input: 0.04,
output: 0.15,
cacheRead: 0,
cacheWrite: 0,
},

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@ -1,9 +1,17 @@
import { describe, expect, it } from "vitest";
import { agentLoop } from "../src/agent/agent-loop.js";
import { agentLoop, agentLoopContinue } from "../src/agent/agent-loop.js";
import { calculateTool } from "../src/agent/tools/calculate.js";
import type { AgentContext, AgentEvent, AgentLoopConfig } from "../src/agent/types.js";
import { getModel } from "../src/models.js";
import type { Api, Message, Model, OptionsForApi, UserMessage } from "../src/types.js";
import type {
Api,
AssistantMessage,
Message,
Model,
OptionsForApi,
ToolResultMessage,
UserMessage,
} from "../src/types.js";
async function calculateTest<TApi extends Api>(model: Model<TApi>, options: OptionsForApi<TApi> = {}) {
// Create the agent context with the calculator tool
@ -282,7 +290,7 @@ describe("Agent Calculator Tests", () => {
});
describe.skipIf(!process.env.ANTHROPIC_API_KEY)("Anthropic Provider Agent", () => {
const model = getModel("anthropic", "claude-3-5-haiku-20241022");
const model = getModel("anthropic", "claude-haiku-4-5");
it("should calculate multiple expressions and sum the results", async () => {
const result = await calculateTest(model);
@ -351,3 +359,175 @@ describe("Agent Calculator Tests", () => {
}, 30000);
});
});
describe("agentLoopContinue", () => {
describe("validation", () => {
const model = getModel("anthropic", "claude-haiku-4-5");
const baseContext: AgentContext = {
systemPrompt: "You are a helpful assistant.",
messages: [],
tools: [],
};
const config: AgentLoopConfig = { model };
it("should throw when context has no messages", () => {
expect(() => agentLoopContinue(baseContext, config)).toThrow("Cannot continue: no messages in context");
});
it("should throw when last message is an assistant message", () => {
const assistantMessage: AssistantMessage = {
role: "assistant",
content: [{ type: "text", text: "Hello" }],
api: "anthropic-messages",
provider: "anthropic",
model: "claude-haiku-4-5",
usage: {
input: 0,
output: 0,
cacheRead: 0,
cacheWrite: 0,
totalTokens: 0,
cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
},
stopReason: "stop",
timestamp: Date.now(),
};
const context: AgentContext = {
...baseContext,
messages: [assistantMessage],
};
expect(() => agentLoopContinue(context, config)).toThrow(
"Cannot continue from message role: assistant. Expected 'user' or 'toolResult'.",
);
});
// Note: "should not throw" tests for valid inputs are covered by the E2E tests below
// which actually consume the stream and verify the output
});
describe.skipIf(!process.env.ANTHROPIC_API_KEY)("continue from user message", () => {
const model = getModel("anthropic", "claude-haiku-4-5");
it("should continue and get assistant response when last message is user", async () => {
const userMessage: UserMessage = {
role: "user",
content: [{ type: "text", text: "Say exactly: HELLO WORLD" }],
timestamp: Date.now(),
};
const context: AgentContext = {
systemPrompt: "You are a helpful assistant. Follow instructions exactly.",
messages: [userMessage],
tools: [],
};
const config: AgentLoopConfig = { model };
const events: AgentEvent[] = [];
const stream = agentLoopContinue(context, config);
for await (const event of stream) {
events.push(event);
}
const messages = await stream.result();
// Should have gotten an assistant response
expect(messages.length).toBe(1);
expect(messages[0].role).toBe("assistant");
// Verify event sequence - no user message events since we're continuing
const eventTypes = events.map((e) => e.type);
expect(eventTypes).toContain("agent_start");
expect(eventTypes).toContain("turn_start");
expect(eventTypes).toContain("message_start");
expect(eventTypes).toContain("message_end");
expect(eventTypes).toContain("turn_end");
expect(eventTypes).toContain("agent_end");
// Should NOT have user message events (that's the difference from agentLoop)
const messageEndEvents = events.filter((e) => e.type === "message_end");
expect(messageEndEvents.length).toBe(1); // Only assistant message
expect((messageEndEvents[0] as any).message.role).toBe("assistant");
}, 30000);
});
describe.skipIf(!process.env.ANTHROPIC_API_KEY)("continue from tool result", () => {
const model = getModel("anthropic", "claude-haiku-4-5");
it("should continue processing after tool results", async () => {
// Simulate a conversation where:
// 1. User asked to calculate something
// 2. Assistant made a tool call
// 3. Tool result is ready
// 4. We continue from here
const userMessage: UserMessage = {
role: "user",
content: [{ type: "text", text: "What is 5 + 3? Use the calculator." }],
timestamp: Date.now(),
};
const assistantMessage: AssistantMessage = {
role: "assistant",
content: [
{ type: "text", text: "Let me calculate that for you." },
{ type: "toolCall", id: "calc-1", name: "calculate", arguments: { expression: "5 + 3" } },
],
api: "anthropic-messages",
provider: "anthropic",
model: "claude-haiku-4-5",
usage: {
input: 0,
output: 0,
cacheRead: 0,
cacheWrite: 0,
totalTokens: 0,
cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
},
stopReason: "toolUse",
timestamp: Date.now(),
};
const toolResult: ToolResultMessage = {
role: "toolResult",
toolCallId: "calc-1",
toolName: "calculate",
content: [{ type: "text", text: "5 + 3 = 8" }],
isError: false,
timestamp: Date.now(),
};
const context: AgentContext = {
systemPrompt: "You are a helpful assistant. After getting a calculation result, state the answer clearly.",
messages: [userMessage, assistantMessage, toolResult],
tools: [calculateTool],
};
const config: AgentLoopConfig = { model };
const events: AgentEvent[] = [];
const stream = agentLoopContinue(context, config);
for await (const event of stream) {
events.push(event);
}
const messages = await stream.result();
// Should have gotten an assistant response
expect(messages.length).toBeGreaterThanOrEqual(1);
const lastMessage = messages[messages.length - 1];
expect(lastMessage.role).toBe("assistant");
// The assistant should mention the result (8)
if (lastMessage.role === "assistant") {
const textContent = lastMessage.content
.filter((c) => c.type === "text")
.map((c) => (c as any).text)
.join(" ");
expect(textContent).toMatch(/8/);
}
}, 30000);
});
});