test(sessions): split pi session service specs

This commit is contained in:
Federico Jaramillo Martinez
2026-07-04 23:53:58 +02:00
parent 04f9d0e764
commit 386386d2b5
7 changed files with 2134 additions and 2105 deletions
@@ -0,0 +1,844 @@
import { mkdtemp, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { describe, expect, it, vi } from "vitest";
import { PiSessionService, type PiAgentSession } from "./piSessionService.js";
import type { SpawnTargetDecision } from "./spawnTargetResolver.js";
import { CapturingSessionEventHub, emptyArchiveStore, fakeRuntime, fakeSessionManager, runtimeCreator, sessionGateway, sessionRecord, sessionRef, testModel, type RuntimeCreator } from "./piSessionService.testSupport.js";
describe("PiSessionService", () => {
describe("spawnSubsession", () => {
function subsessionService(decision: SpawnTargetDecision, heartbeatIntervalMs = 60_000) {
const parent = fakeRuntime("parent-1", { sessionFile: "/tmp/parent-1.jsonl" });
const child = fakeRuntime("child-1", { sessionFile: "/tmp/child-1.jsonl", sessionManager: fakeSessionManager("/workspace-feature") });
const created = [parent.runtime, child.runtime];
let index = 0;
const createAgentRuntime: RuntimeCreator = async () => {
await Promise.resolve();
const runtime = created[Math.min(index, created.length - 1)] ?? child.runtime;
index += 1;
return runtime;
};
const archived = new Map<string, { sessionId: string; cwd: string; archivedAt: string }>();
const archiveStore = {
list: () => Promise.resolve([...archived.values()]),
get: (sessionId: string) => Promise.resolve(archived.get(sessionId)),
archive: (input: { sessionId: string; cwd: string }) => {
const record = { sessionId: input.sessionId, cwd: input.cwd, archivedAt: "2026-01-01T00:00:00.000Z" };
archived.set(input.sessionId, record);
return Promise.resolve(record);
},
restore: (sessionId: string) => { archived.delete(sessionId); return Promise.resolve(); },
isArchived: (sessionId: string) => Promise.resolve(archived.has(sessionId)),
};
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime,
sessionManager: sessionGateway([]),
archiveStore,
spawnTargets: { resolveSpawnTarget: () => Promise.resolve(decision) },
heartbeatIntervalMs,
});
return { parent, child, service };
}
it("records the parent, delivers the prompt, and lists the tracked child", async () => {
const { child, service } = subsessionService({ allowed: true, cwd: "/workspace-feature" });
await service.start("/workspace"); // bring the parent online so it can be notified
const result = await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "do the slice", cwd: "/workspace-feature" });
expect(result).toEqual({ sessionId: "child-1", cwd: "/workspace-feature" });
expect(child.calls.prompt).toEqual([{ text: "do the slice", options: undefined }]);
await expect(service.listSubsessions("parent-1")).resolves.toEqual([
{ sessionId: "child-1", cwd: "/workspace-feature", status: "idle" },
]);
await service.dispose();
});
it("uses the parent session's model as the tracked child's initial model", async () => {
const parent = fakeRuntime("parent-1", { sessionFile: "/tmp/parent-1.jsonl" });
const child = fakeRuntime("child-1", { sessionFile: "/tmp/child-1.jsonl", sessionManager: fakeSessionManager("/workspace-feature") });
const model = testModel();
const initialModels: PiAgentSession["model"][] = [];
const runtimes = [parent.runtime, child.runtime];
let index = 0;
const createAgentRuntime: RuntimeCreator = async (_createRuntime, options) => {
await Promise.resolve();
initialModels.push(options.initialModel);
const runtime = runtimes[index] ?? child.runtime;
index += 1;
return runtime;
};
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime,
sessionManager: sessionGateway([]),
archiveStore: emptyArchiveStore(),
spawnTargets: { resolveSpawnTarget: () => Promise.resolve({ allowed: true, cwd: "/workspace-feature" }) },
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "do the slice", cwd: "/workspace-feature", model });
expect(initialModels).toEqual([undefined, model]);
await service.dispose();
});
it("persists tracked child links in the parent and child sessions", async () => {
const parentPersisted: { customType: string; data?: unknown }[] = [];
const childPersisted: { customType: string; data?: unknown }[] = [];
const parent = fakeRuntime("parent-1", {
sessionFile: "/tmp/parent-1.jsonl",
sessionManager: fakeSessionManager("/workspace", {
appendCustomEntry: (customType, data) => {
parentPersisted.push({ customType, data });
return "parent-entry-1";
},
}),
});
const child = fakeRuntime("child-1", {
sessionFile: "/tmp/child-1.jsonl",
sessionManager: fakeSessionManager("/workspace-feature", {
appendCustomEntry: (customType, data) => {
childPersisted.push({ customType, data });
return "child-entry-1";
},
}),
});
const runtimes = [parent.runtime, child.runtime];
let index = 0;
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? child.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: sessionGateway([]),
archiveStore: emptyArchiveStore(),
spawnTargets: { resolveSpawnTarget: () => Promise.resolve({ allowed: true, cwd: "/workspace-feature" }) },
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "do the slice", cwd: "/workspace-feature" });
expect(parentPersisted).toEqual([
{
customType: "pi-web.subsession.link",
data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: "/tmp/child-1.jsonl", cwd: "/workspace-feature" },
},
]);
expect(childPersisted).toEqual([
{
customType: "pi-web.subsession.spawned",
data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" },
},
]);
await service.dispose();
});
it("hydrates persisted child links after a service restart so the parent can inspect them", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-"));
const parentFile = join(tempDir, "parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getBranch: () => [{ type: "message", message: { role: "assistant", content: "finished" } }],
});
const parent = fakeRuntime("parent-1", {
sessionFile: parentFile,
sessionManager: fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
}),
});
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const runtimes = [parent.runtime, child.runtime];
let index = 0;
const open = vi.fn(() => childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? child.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: { create: () => parent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([]), open },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.checkSubsession("parent-1", "child-1")).resolves.toEqual({
sessionId: "child-1",
cwd: "/workspace-feature",
status: "idle",
finalText: "finished",
messageCount: 1,
});
expect(open).toHaveBeenCalledWith(childFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("ignores stale persisted child links when the child no longer records the parent", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-stale-"));
const parentFile = join(tempDir, "parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature" })}\n`, "utf8");
try {
const parent = fakeRuntime("parent-1", {
sessionFile: parentFile,
sessionManager: fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
}),
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(parent.runtime),
sessionManager: { create: () => parent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([]), open: () => fakeSessionManager() },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.listSubsessions("parent-1")).resolves.toEqual([]);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("does not hydrate persisted links when the exact child file is unavailable", async () => {
const parentFile = "/sessions/parent-1.jsonl";
const parent = fakeRuntime("parent-1", {
sessionFile: parentFile,
sessionManager: fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: "/sessions/child-1.jsonl", cwd: "/workspace-feature" } }],
}),
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(parent.runtime),
sessionManager: { create: () => parent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([]), open: () => fakeSessionManager() },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.listSubsessions("parent-1")).resolves.toEqual([]);
await service.dispose();
});
it("does not hydrate parent links without a child file", async () => {
const parentFile = "/sessions/parent-1.jsonl";
const parent = fakeRuntime("parent-1", {
sessionFile: parentFile,
sessionManager: fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child", cwd: "/workspace-feature" } }],
}),
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(parent.runtime),
sessionManager: { create: () => parent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([]), open: () => fakeSessionManager() },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.listSubsessions("parent-1")).resolves.toEqual([]);
await service.dispose();
});
it("does not invent subsession links from existing child session headers", async () => {
const parentFile = "/sessions/parent-1.jsonl";
const childRecord = { ...sessionRecord("child-1", "/workspace-feature"), path: "/sessions/child-1.jsonl", parentSessionPath: parentFile };
const parent = fakeRuntime("parent-1", {
sessionFile: parentFile,
sessionManager: fakeSessionManager("/workspace", { getEntries: () => [] }),
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(parent.runtime),
sessionManager: { create: () => parent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([childRecord]), open: () => fakeSessionManager() },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.listSubsessions("parent-1")).resolves.toEqual([]);
await service.dispose();
});
it("does not hydrate copied parent links when the opened parent has a different id", async () => {
const forkedParent = fakeRuntime("parent-fork-1", {
sessionFile: "/sessions/parent-fork-1.jsonl",
sessionManager: fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: "/sessions/child-1.jsonl", cwd: "/workspace-feature" } }],
}),
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(forkedParent.runtime),
sessionManager: { create: () => forkedParent.session.sessionManager, list: () => Promise.resolve([]), listAll: () => Promise.resolve([]), open: () => fakeSessionManager() },
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.start("/workspace");
await expect(service.listSubsessions("parent-fork-1")).resolves.toEqual([]);
await service.dispose();
});
it("relinks a spawned child when the child session is opened after restart", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-open-child-"));
const parentFile = join(tempDir, "parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: parentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
});
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const runtimes = [child.runtime, parent.runtime];
let index = 0;
const open = vi.fn((path: string) => path === parentFile ? parentManager : childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? parent.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: {
create: () => childManager,
list: () => Promise.resolve([{ ...sessionRecord("child-1", "/workspace-feature"), path: childFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(1);
expect(parent.calls.sendCustomMessage[0]?.message.content).toContain("Subsession child-1 stopped working");
expect(open).toHaveBeenCalledWith(parentFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("notifies the validated parent file instead of an active prefix-matched parent id", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-prefix-parent-"));
const parentFile = join(tempDir, "parent.jsonl");
const forkParentFile = join(tempDir, "parent-fork.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(forkParentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1-fork", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: parentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
});
const forkManager = fakeSessionManager("/workspace");
const fork = fakeRuntime("parent-1-fork", { sessionFile: forkParentFile, sessionManager: forkManager });
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const runtimes = [fork.runtime, child.runtime, parent.runtime];
let index = 0;
const open = vi.fn((path: string) => {
if (path === parentFile) return parentManager;
if (path === forkParentFile) return forkManager;
return childManager;
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? parent.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: {
create: () => forkManager,
list: (cwd: string) => Promise.resolve(cwd === "/workspace"
? [{ ...sessionRecord("parent-1-fork", "/workspace"), path: forkParentFile }]
: [{ ...sessionRecord("child-1", "/workspace-feature"), path: childFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("parent-1-fork", "/workspace"));
await service.status(sessionRef("child-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(fork.calls.sendCustomMessage).toHaveLength(0);
expect(parent.calls.sendCustomMessage).toHaveLength(1);
expect(open).toHaveBeenCalledWith(parentFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("does not relink a copied child with the original session id unless the parent link names the current child file", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-copied-child-"));
const parentFile = join(tempDir, "parent.jsonl");
const originalChildFile = join(tempDir, "original-child.jsonl");
const copiedChildFile = join(tempDir, "copied-child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(originalChildFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
await writeFile(copiedChildFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: parentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: originalChildFile, cwd: "/workspace-feature" } }],
});
const child = fakeRuntime("child-1", { sessionFile: copiedChildFile, sessionManager: childManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const runtimes = [child.runtime, parent.runtime];
let index = 0;
const open = vi.fn((path: string) => path === parentFile ? parentManager : childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? parent.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: {
create: () => childManager,
list: () => Promise.resolve([{ ...sessionRecord("child-1", "/workspace-feature"), path: copiedChildFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(0);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("uses the verified child file instead of an active copied child with the same id", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-active-copy-child-"));
const parentFile = join(tempDir, "parent.jsonl");
const originalChildFile = join(tempDir, "original-child.jsonl");
const copiedChildFile = join(tempDir, "copied-child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(originalChildFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
await writeFile(copiedChildFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const copiedManager = fakeSessionManager("/workspace-feature", {
getBranch: () => [{ type: "message", message: { role: "assistant", content: "copied child result" } }],
});
const originalManager = fakeSessionManager("/workspace-feature", {
getBranch: () => [{ type: "message", message: { role: "assistant", content: "original child result" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: originalChildFile, cwd: "/workspace-feature" } }],
});
const copiedChild = fakeRuntime("child-1", { sessionFile: copiedChildFile, sessionManager: copiedManager, isStreaming: true });
const originalChild = fakeRuntime("child-1", { sessionFile: originalChildFile, sessionManager: originalManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const createAgentRuntime: RuntimeCreator = (_createRuntime, options) => {
if (options.sessionManager === copiedManager) return Promise.resolve(copiedChild.runtime);
if (options.sessionManager === originalManager) return Promise.resolve(originalChild.runtime);
if (options.sessionManager === parentManager) return Promise.resolve(parent.runtime);
throw new Error("unexpected session manager");
};
const open = vi.fn((path: string) => {
if (path === copiedChildFile) return copiedManager;
if (path === originalChildFile) return originalManager;
if (path === parentFile) return parentManager;
throw new Error(`unexpected open path ${path}`);
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime,
sessionManager: {
create: () => parentManager,
list: (cwd: string) => Promise.resolve(cwd === "/workspace-feature" ? [{ ...sessionRecord("child-1", "/workspace-feature"), path: copiedChildFile, parentSessionPath: parentFile }] : []),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
await service.start("/workspace");
await expect(service.listSubsessions("parent-1", parentFile)).resolves.toEqual([
{ sessionId: "child-1", cwd: "/workspace-feature", status: "idle" },
]);
copiedChild.session.isStreaming = true;
copiedChild.emit({ type: "agent_start" });
copiedChild.session.isStreaming = false;
copiedChild.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(0);
await expect(service.checkSubsession("parent-1", "child-1", parentFile)).resolves.toMatchObject({
sessionId: "child-1",
cwd: "/workspace-feature",
status: "idle",
finalText: "original child result",
messageCount: 1,
});
const read = await service.readSubsession("parent-1", "child-1", { roles: ["assistant"] }, parentFile);
expect(read.entries[0]?.parts[0]).toMatchObject({ kind: "text", text: "original child result" });
expect(open).toHaveBeenCalledWith(originalChildFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("uses the verified parent file instead of an active copied parent with the same id", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-active-copy-parent-"));
const parentFile = join(tempDir, "parent.jsonl");
const copiedParentFile = join(tempDir, "copied-parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(copiedParentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: parentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
getBranch: () => [{ type: "message", message: { role: "assistant", content: "child result" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
});
const copiedParentManager = fakeSessionManager("/workspace", { getEntries: () => [] });
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const copiedParent = fakeRuntime("parent-1", { sessionFile: copiedParentFile, sessionManager: copiedParentManager });
const createAgentRuntime: RuntimeCreator = (_createRuntime, options) => {
if (options.sessionManager === childManager) return Promise.resolve(child.runtime);
if (options.sessionManager === parentManager) return Promise.resolve(parent.runtime);
if (options.sessionManager === copiedParentManager) return Promise.resolve(copiedParent.runtime);
throw new Error("unexpected session manager");
};
const open = vi.fn((path: string) => {
if (path === childFile) return childManager;
if (path === parentFile) return parentManager;
if (path === copiedParentFile) return copiedParentManager;
throw new Error(`unexpected open path ${path}`);
});
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime,
sessionManager: {
create: () => copiedParentManager,
list: (cwd: string) => Promise.resolve(cwd === "/workspace"
? [{ ...sessionRecord("parent-1", "/workspace"), path: copiedParentFile }]
: [{ ...sessionRecord("child-1", "/workspace-feature"), path: childFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
await service.status(sessionRef("parent-1", "/workspace"));
await expect(service.listSubsessions("parent-1", copiedParentFile)).resolves.toEqual([]);
await expect(service.checkSubsession("parent-1", "child-1", copiedParentFile)).rejects.toThrow("not one of your subsessions");
await expect(service.readSubsession("parent-1", "child-1", {}, copiedParentFile)).rejects.toThrow("not one of your subsessions");
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(copiedParent.calls.sendCustomMessage).toHaveLength(0);
expect(parent.calls.sendCustomMessage).toHaveLength(1);
expect(parent.calls.sendCustomMessage[0]?.message.content).toContain("Subsession child-1 stopped working");
expect(open).toHaveBeenCalledWith(parentFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("does not relink a child marker when the current child file header no longer records the parent", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-stale-child-header-"));
const parentFile = join(tempDir, "parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(parentFile, `${JSON.stringify({ type: "session", version: 3, id: "parent-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature" })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: parentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const parentManager = fakeSessionManager("/workspace", {
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.link", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1", spawnedSessionFile: childFile, cwd: "/workspace-feature" } }],
});
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const parent = fakeRuntime("parent-1", { sessionFile: parentFile, sessionManager: parentManager });
const runtimes = [child.runtime, parent.runtime];
let index = 0;
const open = vi.fn((path: string) => path === parentFile ? parentManager : childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? parent.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: {
create: () => childManager,
list: () => Promise.resolve([{ ...sessionRecord("child-1", "/workspace-feature"), path: childFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: {
...emptyArchiveStore(),
get: (sessionId) => Promise.resolve(sessionId === "child-1" ? { sessionId: "child-1", cwd: "/workspace-feature", archivedAt: "2026-01-01T00:00:00.000Z", parentSessionPath: parentFile } : undefined),
},
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(0);
expect(open).not.toHaveBeenCalledWith(parentFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("does not relink a child marker when the child header points at a different parent id", async () => {
const tempDir = await mkdtemp(join(tmpdir(), "pi-web-subsession-wrong-parent-"));
const mismatchedParentFile = join(tempDir, "other-parent.jsonl");
const actualParentFile = join(tempDir, "parent.jsonl");
const childFile = join(tempDir, "child.jsonl");
await writeFile(mismatchedParentFile, `${JSON.stringify({ type: "session", version: 3, id: "other-parent", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace" })}\n`, "utf8");
await writeFile(childFile, `${JSON.stringify({ type: "session", version: 3, id: "child-1", timestamp: "2026-01-01T00:00:00.000Z", cwd: "/workspace-feature", parentSession: mismatchedParentFile })}\n`, "utf8");
try {
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: mismatchedParentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const parent = fakeRuntime("parent-1", { sessionFile: actualParentFile, sessionManager: fakeSessionManager("/workspace") });
const child = fakeRuntime("child-1", { sessionFile: childFile, sessionManager: childManager });
const runtimes = [child.runtime, parent.runtime];
let index = 0;
const open = vi.fn((path: string) => path === actualParentFile ? parent.session.sessionManager : childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: () => {
const runtime = runtimes[index] ?? parent.runtime;
index += 1;
return Promise.resolve(runtime);
},
sessionManager: {
create: () => childManager,
list: () => Promise.resolve([{ ...sessionRecord("child-1", "/workspace-feature"), path: childFile, parentSessionPath: mismatchedParentFile }]),
listAll: () => Promise.resolve([{ ...sessionRecord("parent-1", "/workspace"), path: actualParentFile }]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(0);
expect(open).not.toHaveBeenCalledWith(actualParentFile);
await service.dispose();
} finally {
await rm(tempDir, { recursive: true, force: true });
}
});
it("does not relink copied child markers when the opened child has a different id", async () => {
const parentFile = "/sessions/parent-1.jsonl";
const childFile = "/sessions/child-fork-1.jsonl";
const childManager = fakeSessionManager("/workspace-feature", {
getHeader: () => ({ parentSession: parentFile }),
getEntries: () => [{ type: "custom", customType: "pi-web.subsession.spawned", data: { version: 1, spawnedBySessionId: "parent-1", spawnedSessionId: "child-1" } }],
});
const child = fakeRuntime("child-fork-1", { sessionFile: childFile, sessionManager: childManager });
const open = vi.fn(() => childManager);
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(child.runtime),
sessionManager: {
create: () => childManager,
list: () => Promise.resolve([{ ...sessionRecord("child-fork-1", "/workspace-feature"), path: childFile, parentSessionPath: parentFile }]),
listAll: () => Promise.resolve([]),
open,
},
archiveStore: emptyArchiveStore(),
heartbeatIntervalMs: 60_000,
});
await service.status(sessionRef("child-fork-1", "/workspace-feature"));
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
child.emit({ type: "agent_end" });
await new Promise((resolve) => setTimeout(resolve, 20));
expect(open).not.toHaveBeenCalledWith(parentFile);
await expect(service.listSubsessions("parent-1")).resolves.toEqual([]);
await service.dispose();
});
it("notifies the parent once when the tracked child stops working", async () => {
const { parent, child, service } = subsessionService({ allowed: true, cwd: "/workspace-feature" });
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "go", cwd: "/workspace-feature" });
parent.calls.prompt.length = 0; // ignore the spawn prompt to the child; focus on the parent notification
child.session.isStreaming = true;
child.emit({ type: "agent_start" }); // arm the notification
child.session.isStreaming = false;
child.emit({ type: "agent_end" }); // fire once
child.emit({ type: "turn_end" }); // must not re-notify
await new Promise((resolve) => setTimeout(resolve, 20)); // the parent notification is delivered via the async custom-message path
expect(parent.calls.sendCustomMessage).toHaveLength(1);
expect(parent.calls.sendCustomMessage[0]?.message.content).toContain("Subsession child-1 stopped working");
expect(parent.calls.sendCustomMessage[0]?.message.customType).toBe("subsession.completion");
expect(parent.calls.sendCustomMessage[0]?.options).toEqual({ triggerTurn: true, deliverAs: "followUp" });
expect(parent.calls.prompt).toHaveLength(0); // not a user-authored message
await service.dispose();
});
it("notifies via the heartbeat when the child settles without a further event", async () => {
const { parent, child, service } = subsessionService({ allowed: true, cwd: "/workspace-feature" }, 10);
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "go", cwd: "/workspace-feature" });
parent.calls.prompt.length = 0;
// The child works, then settles silently: agent_end arrives while it still
// reports active work, so the event-driven latch does not fire here.
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.emit({ type: "agent_end" });
expect(parent.calls.sendCustomMessage).toHaveLength(0);
// Once the session settles, the periodic heartbeat re-check notifies.
child.session.isStreaming = false;
await new Promise((resolve) => setTimeout(resolve, 40));
expect(parent.calls.sendCustomMessage).toHaveLength(1);
expect(parent.calls.sendCustomMessage[0]?.message.content).toContain("Subsession child-1 stopped working");
await service.dispose();
});
it("does not notify the parent when a tracked child is archived", async () => {
const { parent, child, service } = subsessionService({ allowed: true, cwd: "/workspace-feature" });
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "go", cwd: "/workspace-feature" });
// Arm the notification, as a real working child would.
child.session.isStreaming = true;
child.emit({ type: "agent_start" });
child.session.isStreaming = false;
parent.calls.sendCustomMessage.length = 0;
await service.archive("child-1");
await new Promise((resolve) => setTimeout(resolve, 20));
expect(parent.calls.sendCustomMessage).toHaveLength(0);
await service.dispose();
});
it("reports a missing tracked child file as unknown in the subsession list", async () => {
const { service } = subsessionService({ allowed: true, cwd: "/workspace-feature" });
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "go", cwd: "/workspace-feature" });
await service.archive("child-1");
await expect(service.listSubsessions("parent-1")).resolves.toEqual([
{ sessionId: "child-1", cwd: "/workspace-feature", status: "unknown" },
]);
await service.dispose();
});
it("check_subsession and read_subsession refuse sessions that are not the caller's children", async () => {
const { service } = subsessionService({ allowed: true, cwd: "/workspace-feature" });
await service.start("/workspace");
await service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "parent-1", parentSessionFile: "/tmp/parent-1.jsonl", prompt: "go", cwd: "/workspace-feature" });
await expect(service.checkSubsession("someone-else", "child-1")).rejects.toThrow("not one of your subsessions");
await expect(service.readSubsession("someone-else", "child-1", {})).rejects.toThrow("not one of your subsessions");
await service.dispose();
});
it("is disabled when no spawn target resolver is configured", async () => {
const fake = fakeRuntime("nope");
const service = new PiSessionService(new CapturingSessionEventHub(), {
createAgentRuntime: runtimeCreator(fake.runtime),
sessionManager: sessionGateway([]),
heartbeatIntervalMs: 60_000,
});
await expect(service.spawnSubsession({ spawningCwd: "/workspace", parentSessionId: "p", parentSessionFile: undefined, prompt: "go", cwd: undefined }))
.rejects.toThrow("Spawning sessions is disabled");
await service.dispose();
});
});
});