feat(core): persist v2 session context epochs

packages/llm/test/provider/anthropic-messages.test.ts

@@ -125,22 +125,56 @@ describe("Anthropic Messages route", () => {
     }),
   )
 
-  it.effect("rejects invalid native chronological system update placement", () =>
+  it.effect("falls back for unsupported native chronological system update placement", () =>
     Effect.gen(function* () {
       const placementError = (messages: Parameters<typeof LLM.request>[0]["messages"]) =>
         LLMClient.prepare(LLM.request({ model: opus48, messages, cache: "none" })).pipe(Effect.flip)
 
-      expect((yield* placementError([Message.system("First.")])).message).toContain("cannot be the first message")
       expect(
-        (yield* placementError([Message.user("Before."), Message.system("One."), Message.system("Two.")])).message,
-      ).toContain("cannot be consecutive")
+        (yield* LLMClient.prepare<AnthropicMessages.AnthropicMessagesBody>(
+          LLM.request({
+            model: opus48,
+            messages: [Message.assistant("Plain."), Message.system("After plain assistant.")],
+            cache: "none",
+          }),
+        )).body.messages,
+      ).toEqual([
+        { role: "assistant", content: [{ type: "text", text: "Plain." }] },
+        {
+          role: "user",
+          content: [{ type: "text", text: "<system-update>\nAfter plain assistant.\n</system-update>" }],
+        },
+      ])
       expect(
-        (yield* placementError([Message.assistant("Plain."), Message.system("After plain assistant.")])).message,
-      ).toContain("must follow a user message, tool result, or assistant server tool use")
+        (yield* LLMClient.prepare<AnthropicMessages.AnthropicMessagesBody>(
+          LLM.request({ model: opus48, messages: [Message.system("First.")], cache: "none" }),
+        )).body.messages,
+      ).toEqual([{ role: "user", content: [{ type: "text", text: "<system-update>\nFirst.\n</system-update>" }] }])
+      expect(
+        (yield* LLMClient.prepare<AnthropicMessages.AnthropicMessagesBody>(
+          LLM.request({
+            model: opus48,
+            messages: [Message.user("Before."), Message.system("One."), Message.system("Two.")],
+            cache: "none",
+          }),
+        )).body.messages,
+      ).toEqual([
+        {
+          role: "user",
+          content: [
+            { type: "text", text: "Before." },
+            { type: "text", text: "<system-update>\nOne.\n</system-update>" },
+            { type: "text", text: "<system-update>\nTwo.\n</system-update>" },
+          ],
+        },
+      ])
       expect(
         (yield* placementError([
           Message.user("Use the tool."),
-          Message.assistant([ToolCallPart.make({ id: "call_1", name: "lookup", input: {} })]),
+          Message.assistant([
+            ToolCallPart.make({ id: "call_1", name: "lookup", input: {} }),
+            { type: "text", text: "Waiting." },
+          ]),
           Message.system("Too early."),
           Message.tool({ id: "call_1", name: "lookup", result: "Done." }),
         ])).message,

packages/llm/test/schema.test.ts

@@ -1,8 +1,18 @@
 import { describe, expect, test } from "bun:test"
-import { Schema } from "effect"
+import { Effect, Schema } from "effect"
 import * as OpenAIChat from "../src/protocols/openai-chat"
 import * as OpenAIResponses from "../src/protocols/openai-responses"
-import { ContentPart, LLMEvent, LLMRequest, Model, ModelID, ProviderID, Usage } from "../src/schema"
+import {
+  ContentPart,
+  LLMEvent,
+  LLMRequest,
+  Message,
+  Model,
+  ModelID,
+  ProviderID,
+  ToolCallPart,
+  Usage,
+} from "../src/schema"
 import { ProviderShared } from "../src/protocols/shared"
 
 const model = new Model({
@@ -54,6 +64,17 @@ describe("llm schema", () => {
     expect(decoded.messages[0]).toMatchObject({ role: "system", content: [{ type: "text", text: "Operator update." }] })
   })
 
+  test("rejects chronological system updates between a local tool call and its result", async () => {
+    const previous = Message.assistant([
+      ToolCallPart.make({ id: "call_1", name: "lookup", input: {} }),
+      { type: "text", text: "Waiting." },
+    ])
+
+    await expect(Effect.runPromise(ProviderShared.guardSystemUpdatePlacement("Test", previous))).rejects.toThrow(
+      "Test chronological system updates cannot appear between a local tool call and its tool result",
+    )
+  })
+
   test("rejects invalid event type", () => {
     expect(() => decodeLLMEvent({ type: "bogus" })).toThrow()
   })