@earendil-works/pi-coding-agent
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Coding agent CLI with read, bash, edit, write tools and session management
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JavaScript
import { uuidv7 } from "@earendil-works/pi-ai";
import { randomUUID } from "crypto";
import { appendFileSync, closeSync, createReadStream, existsSync, mkdirSync, openSync, readdirSync, readSync, statSync, writeFileSync, } from "fs";
import { readdir, stat } from "fs/promises";
import { join, resolve } from "path";
import { createInterface } from "readline";
import { StringDecoder } from "string_decoder";
import { getAgentDir as getDefaultAgentDir, getSessionsDir } from "../config.js";
import { normalizePath, resolvePath } from "../utils/paths.js";
import { createBranchSummaryMessage, createCompactionSummaryMessage, createCustomMessage, } from "./messages.js";
export const CURRENT_SESSION_VERSION = 3;
function createSessionId() {
return uuidv7();
}
export function assertValidSessionId(id) {
if (!/^[A-Za-z0-9](?:[A-Za-z0-9._-]*[A-Za-z0-9])?$/.test(id)) {
throw new Error("Session id must be non-empty, contain only alphanumeric characters, '-', '_', and '.', and start and end with an alphanumeric character");
}
}
/** Generate a unique short ID (8 hex chars, collision-checked) */
function generateId(byId) {
for (let i = 0; i < 100; i++) {
const id = randomUUID().slice(0, 8);
if (!byId.has(id))
return id;
}
// Fallback to full UUID if somehow we have collisions
return randomUUID();
}
/** Migrate v1 → v2: add id/parentId tree structure. Mutates in place. */
function migrateV1ToV2(entries) {
const ids = new Set();
let prevId = null;
for (const entry of entries) {
if (entry.type === "session") {
entry.version = 2;
continue;
}
entry.id = generateId(ids);
entry.parentId = prevId;
prevId = entry.id;
// Convert firstKeptEntryIndex to firstKeptEntryId for compaction
if (entry.type === "compaction") {
const comp = entry;
if (typeof comp.firstKeptEntryIndex === "number") {
const targetEntry = entries[comp.firstKeptEntryIndex];
if (targetEntry && targetEntry.type !== "session") {
comp.firstKeptEntryId = targetEntry.id;
}
delete comp.firstKeptEntryIndex;
}
}
}
}
/** Migrate v2 → v3: rename hookMessage role to custom. Mutates in place. */
function migrateV2ToV3(entries) {
for (const entry of entries) {
if (entry.type === "session") {
entry.version = 3;
continue;
}
// Update message entries with hookMessage role
if (entry.type === "message") {
const msgEntry = entry;
if (msgEntry.message && msgEntry.message.role === "hookMessage") {
msgEntry.message.role = "custom";
}
}
}
}
/**
* Run all necessary migrations to bring entries to current version.
* Mutates entries in place. Returns true if any migration was applied.
*/
function migrateToCurrentVersion(entries) {
const header = entries.find((e) => e.type === "session");
const version = header?.version ?? 1;
if (version >= CURRENT_SESSION_VERSION)
return false;
if (version < 2)
migrateV1ToV2(entries);
if (version < 3)
migrateV2ToV3(entries);
return true;
}
/** Exported for testing */
export function migrateSessionEntries(entries) {
migrateToCurrentVersion(entries);
}
/** Exported for compaction.test.ts */
export function parseSessionEntries(content) {
const entries = [];
const lines = content.trim().split("\n");
for (const line of lines) {
if (!line.trim())
continue;
try {
const entry = JSON.parse(line);
entries.push(entry);
}
catch {
// Skip malformed lines
}
}
return entries;
}
export function getLatestCompactionEntry(entries) {
for (let i = entries.length - 1; i >= 0; i--) {
if (entries[i].type === "compaction") {
return entries[i];
}
}
return null;
}
function buildEntryIndex(entries, byId) {
if (byId)
return byId;
const index = new Map();
for (const entry of entries) {
index.set(entry.id, entry);
}
return index;
}
function buildSessionPath(entries, leafId, byId) {
const index = buildEntryIndex(entries, byId);
let leaf;
if (leafId === null) {
return [];
}
if (leafId) {
leaf = index.get(leafId);
}
leaf ??= entries[entries.length - 1];
if (!leaf) {
return [];
}
const path = [];
let current = leaf;
while (current) {
path.push(current);
current = current.parentId ? index.get(current.parentId) : undefined;
}
path.reverse();
return path;
}
function getSessionContextSettings(path) {
let thinkingLevel = "off";
let model = null;
for (const entry of path) {
if (entry.type === "thinking_level_change") {
thinkingLevel = entry.thinkingLevel;
}
else if (entry.type === "model_change") {
model = { provider: entry.provider, modelId: entry.modelId };
}
else if (entry.type === "message" && entry.message.role === "assistant") {
model = { provider: entry.message.provider, modelId: entry.message.model };
}
}
return { thinkingLevel, model };
}
/**
* Project one selected session entry into LLM/runtime messages.
* Plain custom entries are display/state entries and do not participate in context.
*/
export function sessionEntryToContextMessages(entry) {
if (entry.type === "message") {
const message = entry.message;
// Session files are parsed without validation; old versions, forks, or
// hand-edited files can contain messages with null/missing content.
if ((message.role === "user" || message.role === "assistant" || message.role === "toolResult") &&
message.content == null) {
return [{ ...message, content: [] }];
}
return [message];
}
if (entry.type === "custom_message") {
return [
createCustomMessage(entry.customType, entry.content ?? [], entry.display, entry.details, entry.timestamp),
];
}
if (entry.type === "branch_summary" && entry.summary) {
return [createBranchSummaryMessage(entry.summary, entry.fromId, entry.timestamp)];
}
if (entry.type === "compaction") {
return [createCompactionSummaryMessage(entry.summary, entry.tokensBefore, entry.timestamp)];
}
return [];
}
/**
* Build the active, compaction-aware session entry list.
*
* This follows the current leaf path. If the path contains compaction entries,
* the latest compaction is represented by the compaction entry itself, followed
* by the kept entries starting at firstKeptEntryId and all entries after the
* compaction entry. Older summarized entries are omitted.
*/
export function buildContextEntries(entries, leafId, byId) {
const path = buildSessionPath(entries, leafId, byId);
let compaction = null;
for (const entry of path) {
if (entry.type === "compaction") {
compaction = entry;
}
}
if (!compaction) {
return path;
}
const compactionIdx = path.findIndex((entry) => entry.id === compaction.id);
if (compactionIdx < 0) {
return path;
}
const contextEntries = [compaction];
let foundFirstKept = false;
for (let i = 0; i < compactionIdx; i++) {
const entry = path[i];
if (entry.id === compaction.firstKeptEntryId) {
foundFirstKept = true;
}
if (foundFirstKept) {
contextEntries.push(entry);
}
}
contextEntries.push(...path.slice(compactionIdx + 1));
return contextEntries;
}
/**
* Build the session context from entries using tree traversal.
* If leafId is provided, walks from that entry to root.
* Handles compaction and branch summaries along the path.
*/
export function buildSessionContext(entries, leafId, byId) {
const path = buildSessionPath(entries, leafId, byId);
const { thinkingLevel, model } = getSessionContextSettings(path);
const messages = buildContextEntries(entries, leafId, byId).flatMap(sessionEntryToContextMessages);
return { messages, thinkingLevel, model };
}
/**
* Compute the default session directory for a cwd.
* Encodes cwd into a safe directory name under ~/.pi/agent/sessions/.
*/
function getDefaultSessionDirPath(cwd, agentDir = getDefaultAgentDir()) {
const resolvedCwd = resolvePath(cwd);
const resolvedAgentDir = resolvePath(agentDir);
const safePath = `--${resolvedCwd.replace(/^[/\\]/, "").replace(/[/\\:]/g, "-")}--`;
return join(resolvedAgentDir, "sessions", safePath);
}
export function getDefaultSessionDir(cwd, agentDir = getDefaultAgentDir()) {
const sessionDir = getDefaultSessionDirPath(cwd, agentDir);
if (!existsSync(sessionDir)) {
mkdirSync(sessionDir, { recursive: true });
}
return sessionDir;
}
const SESSION_READ_BUFFER_SIZE = 1024 * 1024;
const SESSION_HEADER_READ_BUFFER_SIZE = 4096;
/** Bound synchronous header discovery while allowing large cwd and custom metadata fields. */
const MAX_SESSION_HEADER_SCAN_BYTES = 1024 * 1024;
class SessionHeaderScanLimitError extends Error {
constructor(filePath) {
super(`Session header exceeds ${MAX_SESSION_HEADER_SCAN_BYTES}-byte scan limit: ${filePath}`);
this.name = "SessionHeaderScanLimitError";
}
}
function parseSessionEntryLine(line) {
if (!line.trim())
return null;
try {
return JSON.parse(line);
}
catch {
// Skip malformed lines
return null;
}
}
/** Exported for testing */
export function loadEntriesFromFile(filePath) {
const resolvedFilePath = normalizePath(filePath);
if (!existsSync(resolvedFilePath))
return [];
const entries = [];
const fd = openSync(resolvedFilePath, "r");
try {
const decoder = new StringDecoder("utf8");
const buffer = Buffer.allocUnsafe(SESSION_READ_BUFFER_SIZE);
let pending = "";
while (true) {
const bytesRead = readSync(fd, buffer, 0, buffer.length, null);
if (bytesRead === 0)
break;
pending += decoder.write(buffer.subarray(0, bytesRead));
let lineStart = 0;
let newlineIndex = pending.indexOf("\n", lineStart);
while (newlineIndex !== -1) {
const entry = parseSessionEntryLine(pending.slice(lineStart, newlineIndex));
if (entry)
entries.push(entry);
lineStart = newlineIndex + 1;
newlineIndex = pending.indexOf("\n", lineStart);
}
pending = pending.slice(lineStart);
}
pending += decoder.end();
const finalEntry = parseSessionEntryLine(pending);
if (finalEntry)
entries.push(finalEntry);
}
finally {
closeSync(fd);
}
// Validate session header
if (entries.length === 0)
return entries;
const header = entries[0];
if (header.type !== "session" || typeof header.id !== "string") {
return [];
}
return entries;
}
/**
* Inspect a physical line while searching for the first parsed session entry.
* Blank and malformed lines are skipped to match loadEntriesFromFile().
* Returns undefined to keep scanning, null for a parsed non-header entry, or the header.
*/
function parseSessionHeaderCandidate(line) {
if (!line.trim())
return undefined;
const entry = parseSessionEntryLine(line);
if (!entry)
return undefined;
if (entry.type !== "session" || typeof entry.id !== "string")
return null;
return entry;
}
function readSessionHeader(filePath) {
const fd = openSync(filePath, "r");
try {
const decoder = new StringDecoder("utf8");
const buffer = Buffer.allocUnsafe(SESSION_HEADER_READ_BUFFER_SIZE);
const lineChunks = [];
let scannedBytes = 0;
while (scannedBytes < MAX_SESSION_HEADER_SCAN_BYTES) {
const readLength = Math.min(buffer.length, MAX_SESSION_HEADER_SCAN_BYTES - scannedBytes);
const bytesRead = readSync(fd, buffer, 0, readLength, null);
if (bytesRead === 0) {
lineChunks.push(decoder.end());
return parseSessionHeaderCandidate(lineChunks.join("")) ?? null;
}
scannedBytes += bytesRead;
const chunk = decoder.write(buffer.subarray(0, bytesRead));
let lineStart = 0;
let newlineIndex = chunk.indexOf("\n", lineStart);
while (newlineIndex !== -1) {
lineChunks.push(chunk.slice(lineStart, newlineIndex));
const header = parseSessionHeaderCandidate(lineChunks.join(""));
if (header !== undefined)
return header;
lineChunks.length = 0;
lineStart = newlineIndex + 1;
newlineIndex = chunk.indexOf("\n", lineStart);
}
lineChunks.push(chunk.slice(lineStart));
}
// Probe for EOF so a final header without a newline is allowed when it ends
// exactly at the scan limit. Any additional byte exceeds the bounded scan.
const probe = Buffer.allocUnsafe(1);
if (readSync(fd, probe, 0, probe.length, null) === 0) {
lineChunks.push(decoder.end());
return parseSessionHeaderCandidate(lineChunks.join("")) ?? null;
}
throw new SessionHeaderScanLimitError(filePath);
}
finally {
closeSync(fd);
}
}
function readSessionHeaderForDiscovery(filePath) {
try {
return readSessionHeader(filePath);
}
catch {
// Discovery is best-effort: unreadable or oversized files are not sessions,
// and one corrupt file must not prevent other sessions from being found.
return null;
}
}
function getSessionHeaderCwd(header) {
const cwd = header.cwd;
return typeof cwd === "string" ? cwd : undefined;
}
function sessionCwdMatches(cwd, resolvedCwd) {
return cwd !== undefined && cwd !== "" && resolvePath(cwd) === resolvedCwd;
}
/** Exported for testing */
export function findMostRecentSession(sessionDir, cwd) {
const resolvedSessionDir = normalizePath(sessionDir);
const resolvedCwd = cwd ? resolvePath(cwd) : undefined;
try {
const files = readdirSync(resolvedSessionDir)
.filter((f) => f.endsWith(".jsonl"))
.map((f) => join(resolvedSessionDir, f))
.map((path) => ({ path, header: readSessionHeaderForDiscovery(path) }))
.filter((file) => file.header !== null &&
(!resolvedCwd || sessionCwdMatches(getSessionHeaderCwd(file.header), resolvedCwd)))
.map(({ path }) => ({ path, mtime: statSync(path).mtime }))
.sort((a, b) => b.mtime.getTime() - a.mtime.getTime());
return files[0]?.path || null;
}
catch {
// Directory access and stat races make recent-session discovery unavailable.
return null;
}
}
function isMessageWithContent(message) {
return typeof message.role === "string" && "content" in message;
}
function extractTextContent(message) {
const content = message.content;
if (typeof content === "string") {
return content;
}
return content
.filter((block) => block.type === "text")
.map((block) => block.text)
.join(" ");
}
function getMessageActivityTime(entry) {
const message = entry.message;
if (!isMessageWithContent(message))
return undefined;
if (message.role !== "user" && message.role !== "assistant")
return undefined;
const msgTimestamp = message.timestamp;
if (typeof msgTimestamp === "number") {
return msgTimestamp;
}
const t = new Date(entry.timestamp).getTime();
return Number.isNaN(t) ? undefined : t;
}
async function buildSessionInfo(filePath) {
try {
const stats = await stat(filePath);
let header = null;
let messageCount = 0;
let firstMessage = "";
const allMessages = [];
let name;
let lastActivityTime;
const rl = createInterface({
input: createReadStream(filePath, { encoding: "utf8" }),
crlfDelay: Infinity,
});
for await (const line of rl) {
const entry = parseSessionEntryLine(line);
if (!entry)
continue;
if (!header) {
if (entry.type !== "session")
return null;
header = entry;
continue;
}
// Extract session name (use latest, including explicit clears)
if (entry.type === "session_info") {
name = entry.name?.trim() || undefined;
}
if (entry.type !== "message")
continue;
messageCount++;
const activityTime = getMessageActivityTime(entry);
if (typeof activityTime === "number") {
lastActivityTime = Math.max(lastActivityTime ?? 0, activityTime);
}
const message = entry.message;
if (!isMessageWithContent(message))
continue;
if (message.role !== "user" && message.role !== "assistant")
continue;
const textContent = extractTextContent(message);
if (!textContent)
continue;
allMessages.push(textContent);
if (!firstMessage && message.role === "user") {
firstMessage = textContent;
}
}
if (!header)
return null;
const cwd = typeof header.cwd === "string" ? header.cwd : "";
const parentSessionPath = header.parentSession;
const headerTime = typeof header.timestamp === "string" ? new Date(header.timestamp).getTime() : NaN;
const modified = typeof lastActivityTime === "number" && lastActivityTime > 0
? new Date(lastActivityTime)
: !Number.isNaN(headerTime)
? new Date(headerTime)
: stats.mtime;
return {
path: filePath,
id: header.id,
cwd,
name,
parentSessionPath,
created: new Date(header.timestamp),
modified,
messageCount,
firstMessage: firstMessage || "(no messages)",
allMessagesText: allMessages.join(" "),
};
}
catch {
return null;
}
}
const MAX_CONCURRENT_SESSION_INFO_LOADS = 10;
async function buildSessionInfosWithConcurrency(files, onLoaded) {
const results = new Array(files.length).fill(null);
const inFlight = new Set();
let nextIndex = 0;
const startNext = () => {
const index = nextIndex++;
const file = files[index];
if (!file)
return;
let task;
task = buildSessionInfo(file)
.then((info) => {
results[index] = info;
})
.catch(() => {
results[index] = null;
})
.finally(() => {
inFlight.delete(task);
onLoaded();
});
inFlight.add(task);
};
while (nextIndex < files.length || inFlight.size > 0) {
while (nextIndex < files.length && inFlight.size < MAX_CONCURRENT_SESSION_INFO_LOADS) {
startNext();
}
if (inFlight.size > 0) {
await Promise.race(inFlight);
}
}
return results;
}
async function listSessionsFromDir(dir, onProgress, progressOffset = 0, progressTotal) {
const sessions = [];
if (!existsSync(dir)) {
return sessions;
}
try {
const dirEntries = await readdir(dir);
const files = dirEntries.filter((f) => f.endsWith(".jsonl")).map((f) => join(dir, f));
const total = progressTotal ?? files.length;
let loaded = 0;
const results = await buildSessionInfosWithConcurrency(files, () => {
loaded++;
onProgress?.(progressOffset + loaded, total);
});
for (const info of results) {
if (info) {
sessions.push(info);
}
}
}
catch {
// Return empty list on error
}
return sessions;
}
/**
* Manages conversation sessions as append-only trees stored in JSONL files.
*
* Each session entry has an id and parentId forming a tree structure. The "leaf"
* pointer tracks the current position. Appending creates a child of the current leaf.
* Branching moves the leaf to an earlier entry, allowing new branches without
* modifying history.
*
* Use buildSessionContext() to get the resolved message list for the LLM, which
* handles compaction summaries and follows the path from root to current leaf.
*/
export class SessionManager {
sessionId = "";
sessionFile;
sessionDir;
cwd;
persist;
flushed = false;
fileEntries = [];
byId = new Map();
labelsById = new Map();
labelTimestampsById = new Map();
leafId = null;
constructor(cwd, sessionDir, sessionFile, persist, newSessionOptions, preloadedFileEntries) {
this.cwd = resolvePath(cwd);
this.sessionDir = normalizePath(sessionDir);
this.persist = persist;
if (persist && this.sessionDir && !existsSync(this.sessionDir)) {
mkdirSync(this.sessionDir, { recursive: true });
}
if (sessionFile) {
this._setSessionFile(sessionFile, preloadedFileEntries);
}
else {
this.newSession(newSessionOptions);
}
}
/** Switch to a different session file (used for resume and branching) */
setSessionFile(sessionFile) {
this._setSessionFile(sessionFile);
}
_setSessionFile(sessionFile, preloadedFileEntries) {
this.sessionFile = resolvePath(sessionFile);
if (existsSync(this.sessionFile)) {
this.fileEntries = preloadedFileEntries ?? loadEntriesFromFile(this.sessionFile);
// If file was empty, initialize it with a valid session header. If it was
// non-empty but did not parse as a pi session, fail without modifying it.
if (this.fileEntries.length === 0) {
const explicitPath = this.sessionFile;
if (statSync(explicitPath).size > 0) {
throw new Error(`Session file is not a valid pi session: ${explicitPath}`);
}
this.newSession();
this.sessionFile = explicitPath;
this._rewriteFile();
this.flushed = true;
return;
}
const header = this.fileEntries.find((e) => e.type === "session");
this.sessionId = header?.id ?? createSessionId();
if (migrateToCurrentVersion(this.fileEntries)) {
this._rewriteFile();
}
this._buildIndex();
this.flushed = true;
}
else {
const explicitPath = this.sessionFile;
this.newSession();
this.sessionFile = explicitPath; // preserve explicit path from --session flag
}
}
newSession(options) {
if (options?.id !== undefined) {
assertValidSessionId(options.id);
}
this.sessionId = options?.id ?? createSessionId();
const timestamp = new Date().toISOString();
const header = {
type: "session",
version: CURRENT_SESSION_VERSION,
id: this.sessionId,
timestamp,
cwd: this.cwd,
parentSession: options?.parentSession,
};
this.fileEntries = [header];
this.byId.clear();
this.labelsById.clear();
this.labelTimestampsById.clear();
this.leafId = null;
this.flushed = false;
if (this.persist) {
const fileTimestamp = timestamp.replace(/[:.]/g, "-");
this.sessionFile = join(this.getSessionDir(), `${fileTimestamp}_${this.sessionId}.jsonl`);
}
return this.sessionFile;
}
_buildIndex() {
this.byId.clear();
this.labelsById.clear();
this.labelTimestampsById.clear();
this.leafId = null;
for (const entry of this.fileEntries) {
if (entry.type === "session")
continue;
this.byId.set(entry.id, entry);
this.leafId = entry.id;
if (entry.type === "label") {
if (entry.label) {
this.labelsById.set(entry.targetId, entry.label);
this.labelTimestampsById.set(entry.targetId, entry.timestamp);
}
else {
this.labelsById.delete(entry.targetId);
this.labelTimestampsById.delete(entry.targetId);
}
}
}
}
_rewriteFile() {
if (!this.persist || !this.sessionFile)
return;
const fd = openSync(this.sessionFile, "w");
try {
for (const entry of this.fileEntries) {
writeFileSync(fd, `${JSON.stringify(entry)}\n`);
}
}
finally {
closeSync(fd);
}
}
isPersisted() {
return this.persist;
}
getCwd() {
return this.cwd;
}
getSessionDir() {
return this.sessionDir;
}
usesDefaultSessionDir() {
return this.sessionDir === getDefaultSessionDirPath(this.cwd);
}
getSessionId() {
return this.sessionId;
}
getSessionFile() {
return this.sessionFile;
}
_persist(entry) {
if (!this.persist || !this.sessionFile)
return;
const hasAssistant = this.fileEntries.some((e) => e.type === "message" && e.message.role === "assistant");
if (!hasAssistant) {
if (this.flushed) {
appendFileSync(this.sessionFile, `${JSON.stringify(entry)}\n`);
}
else {
// Mark as not flushed so when assistant arrives, all entries get written
this.flushed = false;
}
return;
}
if (!this.flushed) {
const fd = openSync(this.sessionFile, "wx");
try {
for (const e of this.fileEntries) {
writeFileSync(fd, `${JSON.stringify(e)}\n`);
}
}
finally {
closeSync(fd);
}
this.flushed = true;
}
else {
appendFileSync(this.sessionFile, `${JSON.stringify(entry)}\n`);
}
}
_appendEntry(entry) {
this.fileEntries.push(entry);
this.byId.set(entry.id, entry);
this.leafId = entry.id;
this._persist(entry);
}
/** Append a message as child of current leaf, then advance leaf. Returns entry id.
* Does not allow writing CompactionSummaryMessage and BranchSummaryMessage directly.
* Reason: we want these to be top-level entries in the session, not message session entries,
* so it is easier to find them.
* These need to be appended via appendCompaction() and appendBranchSummary() methods.
*/
appendMessage(message) {
const entry = {
type: "message",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
message,
};
this._appendEntry(entry);
return entry.id;
}
/** Append a thinking level change as child of current leaf, then advance leaf. Returns entry id. */
appendThinkingLevelChange(thinkingLevel) {
const entry = {
type: "thinking_level_change",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
thinkingLevel,
};
this._appendEntry(entry);
return entry.id;
}
/** Append a model change as child of current leaf, then advance leaf. Returns entry id. */
appendModelChange(provider, modelId) {
const entry = {
type: "model_change",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
provider,
modelId,
};
this._appendEntry(entry);
return entry.id;
}
/** Append a compaction summary as child of current leaf, then advance leaf. Returns entry id. */
appendCompaction(summary, firstKeptEntryId, tokensBefore, details, fromHook, usage) {
const entry = {
type: "compaction",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
summary,
firstKeptEntryId,
tokensBefore,
details,
usage,
fromHook,
};
this._appendEntry(entry);
return entry.id;
}
/** Append a custom entry (for extensions) as child of current leaf, then advance leaf. Returns entry id. */
appendCustomEntry(customType, data) {
const entry = {
type: "custom",
customType,
data,
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
};
this._appendEntry(entry);
return entry.id;
}
/** Append a session info entry (e.g., display name). Returns entry id. */
appendSessionInfo(name) {
const sanitizedName = name.replace(/[\r\n]+/g, " ").trim();
const entry = {
type: "session_info",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
name: sanitizedName,
};
this._appendEntry(entry);
return entry.id;
}
/** Get the current session name from the latest session_info entry, if any. */
getSessionName() {
// Walk entries in reverse to find the latest session_info entry.
// Empty names explicitly clear the session title.
const entries = this.getEntries();
for (let i = entries.length - 1; i >= 0; i--) {
const entry = entries[i];
if (entry.type === "session_info") {
return entry.name?.trim() || undefined;
}
}
return undefined;
}
/**
* Append a custom message entry (for extensions) that participates in LLM context.
* @param customType Extension identifier for filtering on reload
* @param content Message content (string or TextContent/ImageContent array)
* @param display Whether to show in TUI (true = styled display, false = hidden)
* @param details Optional extension-specific metadata (not sent to LLM)
* @returns Entry id
*/
appendCustomMessageEntry(customType, content, display, details) {
const entry = {
type: "custom_message",
customType,
content,
display,
details,
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
};
this._appendEntry(entry);
return entry.id;
}
// =========================================================================
// Tree Traversal
// =========================================================================
getLeafId() {
return this.leafId;
}
getLeafEntry() {
return this.leafId ? this.byId.get(this.leafId) : undefined;
}
getEntry(id) {
return this.byId.get(id);
}
/**
* Get all direct children of an entry.
*/
getChildren(parentId) {
const children = [];
for (const entry of this.byId.values()) {
if (entry.parentId === parentId) {
children.push(entry);
}
}
return children;
}
/**
* Get the label for an entry, if any.
*/
getLabel(id) {
return this.labelsById.get(id);
}
/**
* Set or clear a label on an entry.
* Labels are user-defined markers for bookmarking/navigation.
* Pass undefined or empty string to clear the label.
*/
appendLabelChange(targetId, label) {
if (!this.byId.has(targetId)) {
throw new Error(`Entry ${targetId} not found`);
}
const entry = {
type: "label",
id: generateId(this.byId),
parentId: this.leafId,
timestamp: new Date().toISOString(),
targetId,
label,
};
this._appendEntry(entry);
if (label) {
this.labelsById.set(targetId, label);
this.labelTimestampsById.set(targetId, entry.timestamp);
}
else {
this.labelsById.delete(targetId);
this.labelTimestampsById.delete(targetId);
}
return entry.id;
}
/**
* Walk from entry to root, returning all entries in path order.
* Includes all entry types (messages, compaction, model changes, etc.).
* Use buildSessionContext() to get the resolved messages for the LLM.
*/
getBranch(fromId) {
const path = [];
const startId = fromId ?? this.leafId;
let current = startId ? this.byId.get(startId) : undefined;
while (current) {
path.push(current);
current = current.parentId ? this.byId.get(current.parentId) : undefined;
}
path.reverse();
return path;
}
/**
* Build the active, compaction-aware entry list for context/rendering.
* Uses tree traversal from current leaf.
*/
buildContextEntries() {
return buildContextEntries(this.getEntries(), this.leafId, this.byId);
}
/**
* Build the session context (what gets sent to the LLM).
* Uses tree traversal from current leaf.
*/
buildSessionContext() {
return buildSessionContext(this.getEntries(), this.leafId, this.byId);
}
/**
* Get session header.
*/
getHeader() {
const h = this.fileEntries.find((e) => e.type === "session");
return h ? h : null;
}
/**
* Get all session entries (excludes header). Returns a shallow copy.
* The session is append-only: use appendXXX() to add entries, branch() to
* change the leaf pointer. Entries cannot be modified or deleted.
*/
getEntries() {
return this.fileEntries.filter((e) => e.type !== "session");
}
/**
* Get the session as a tree structure. Returns a shallow defensive copy of all entries.
* A well-formed session has exactly one root (first entry with parentId === null).
* Orphaned entries (broken parent chain) are also returned as roots.
*/
getTree() {
const entries = this.getEntries();
const nodeMap = new Map();
const roots = [];
// Create nodes with resolved labels
for (const entry of entries) {
const label = this.labelsById.get(entry.id);
const labelTimestamp = this.labelTimestampsById.get(entry.id);
nodeMap.set(entry.id, { entry, children: [], label, labelTimestamp });
}
// Build tree
for (const entry of entries) {
const node = nodeMap.get(entry.id);
if (entry.parentId === null || entry.parentId === entry.id) {
roots.push(node);
}
else {
const parent = nodeMap.get(entry.parentId);
if (parent) {
parent.children.push(node);
}
else {
// Orphan - treat as root
roots.push(node);
}
}
}
// Sort children by timestamp (oldest first, newest at bottom)
// Use iterative approach to avoid stack overflow on deep trees
const stack = [...roots];
while (stack.length > 0) {
const node = stack.pop();
node.children.sort((a, b) => new Date(a.entry.timestamp).getTime() - new Date(b.entry.timestamp).getTime());
stack.push(...node.children);
}
return roots;
}
// =========================================================================
// Branching
// =========================================================================
/**
* Start a new branch from an earlier entry.
* Moves the leaf pointer to the specified entry. The next appendXXX() call
* will create a child of that entry, forming a new branch. Existing entries
* are not modified or deleted.
*/
branch(branchFromId) {
if (!this.byId.has(branchFromId)) {
throw new Error(`Entry ${branchFromId} not found`);
}
this.leafId = branchFromId;
}
/**
* Reset the leaf pointer to null (before any entries).
* The next appendXXX() call will create a new root entry (parentId = null).
* Use this when navigating to re-edit the first user message.
*/
resetLeaf() {
this.leafId = null;
}
/**
* Start a new branch with a summary of the abandoned path.
* Same as branch(), but also appends a branch_summary entry that captures
* context from the abandoned conversation path.
*/
branchWithSummary(branchFromId, summary, details, fromHook, usage) {
if (branchFromId !== null && !this.byId.has(branchFromId)) {
throw new Error(`Entry ${branchFromId} not found`);
}
this.leafId = branchFromId;
const entry = {
type: "branch_summary",
id: generateId(this.byId),
parentId: branchFromId,
timestamp: new Date().toISOString(),
fromId: branchFromId ?? "root",
summary,
details,
usage,
fromHook,
};
this._appendEntry(entry);
return entry.id;
}
/**
* Create a new session file containing only the path from root to the specified leaf.
* Useful for extracting a single conversation path from a branched session.
* Returns the new session file path, or undefined if not persisting.
*/
createBranchedSession(leafId) {
const previousSessionFile = this.sessionFile;
const path = this.getBranch(leafId);
if (path.length === 0) {
throw new Error(`Entry ${leafId} not found`);
}
// Filter out LabelEntry from path - we'll recreate them from the resolved map.
// Because labels are real tree entries, later entries can be children of labels;
// removing labels requires re-chaining the retained path to avoid orphaned subtrees.
const pathWithoutLabels = [];
let pathParentId = null;
for (const entry of path) {
if (entry.type === "label")
continue;
pathWithoutLabels.push({ ...entry, parentId: pathParentId });
pathParentId = entry.id;
}
const newSessionId = createSessionId();
const timestamp = new Date().toISOString();
const fileTimestamp = timestamp.replace(/[:.]/g, "-");
const newSessionFile = join(this.getSessionDir(), `${fileTimestamp}_${newSessionId}.jsonl`);
const header = {
type: "session",
version: CURRENT_SESSION_VERSION,
id: newSessionId,
timestamp,
cwd: this.cwd,
parentSession: this.persist ? previousSessionFile : undefined,
};
// Collect labels for entries in the path
const pathEntryIds = new Set(pathWithoutLabels.map((e) => e.id));
const labelsToWrite = [];
for (const [targetId, label] of this.labelsById) {
if (pathEntryIds.has(targetId)) {
labelsToWrite.push({ targetId, label, timestamp: this.labelTimestampsById.get(targetId) });
}
}
if (this.persist) {
// Build label entries
const lastEntryId = pathWithoutLabels[pathWithoutLabels.length - 1]?.id || null;
let parentId = lastEntryId;
const labelEntries = [];
for (const { targetId, label, timestamp: labelTimestamp } of labelsToWrite) {
const labelEntry = {
type: "label",
id: generateId(new Set(pathEntryIds)),
parentId,
timestamp: labelTimestamp,
targetId,
label,
};
pathEntryIds.add(labelEntry.id);
labelEntries.push(labelEntry);
parentId = labelEntry.id;
}
this.fileEntries = [header, ...pathWithoutLabels, ...labelEntries];
this.sessionId = newSessionId;
this.sessionFile = newSessionFile;
this._buildIndex();
// Only write the file now if it contains an assistant message.
// Otherwise defer to _persist(), which creates the file on the
// first assistant response, matching the newSession() contract
// and avoiding the duplicate-header bug when _persist()'s
// no-assistant guard later resets flushed to false.
const hasAssistant = this.fileEntries.some((e) => e.type === "message" && e.message.role === "assistant");
if (hasAssistant) {
this._rewriteFile();
this.flushed = true;
}
else {
this.flushed = false;
}
return newSessionFile;
}
// In-memory mode: replace current session with the path + labels
const labelEntries = [];
let parentId = pathWithoutLabels[pathWithoutLabels.length - 1]?.id || null;
for (const { targetId, label, timestamp: labelTimestamp } of labelsToWrite) {
const labelEntry = {
type: "label",
id: generateId(new Set([...pathEntryIds, ...labelEntries.map((e) => e.id)])),
parentId,
timestamp: labelTimestamp,
targetId,
label,
};
labelEntries.push(labelEntry);
parentId = labelEntry.id;
}
this.fileEntries = [header, ...pathWithoutLabels, ...labelEntries];
this.sessionId = newSessionId;
this._buildIndex();
return undefined;
}
/**
* Create a new session.
* @param cwd Working directory (stored in session header)
* @param sessionDir Optional session directory. If omitted, uses default (~/.pi/agent/sessions/<encoded-cwd>/).
*/
static create(cwd, sessionDir, options) {
const dir = sessionDir ? normalizePath(sessionDir) : getDefaultSessionDir(cwd);
return new SessionManager(cwd, dir, undefined, true, options);
}
/**
* Open a specific session file.
* @param path Path to session file
* @param sessionDir Optional session directory for /new or /branch. If omitted, derives from file's parent.
* @param cwdOverride Optional cwd override instead of the session header cwd.
*/
static open(path, sessionDir, cwdOverride) {
const resolvedPath = resolvePath(path);
let header = null;
let preloadedFileEntries;
if (cwdOverride === undefined && existsSync(resolvedPath)) {
try {
header = readSessionHeader(resolvedPath);
}
catch (error) {
if (!(error instanceof SessionHeaderScanLimitError))
throw error;
// The bounded scan is only a discovery optimization. A full load remains
// authoritative for legacy files with very large headers or prefixes.
preloadedFileEntries = loadEntriesFromFile(resolvedPath);
const firstEntry = preloadedFileEntries[0];
header = firstEntry?.type === "session" ? firstEntry : null;
}
}
const cwd = cwdOverride ?? (header ? getSessionHeaderCwd(header) : undefined) ?? process.cwd();
// If no sessionDir provided, derive from file's parent directory
const dir = sessionDir ? normalizePath(sessionDir) : resolve(resolvedPath, "..");
return new SessionManager(cwd, dir, resolvedPath, true, undefined, preloadedFileEntries);
}
/**
* Continue the most recent session, or create new if none.
* @param cwd Working directory
* @param sessionDir Optional session directory. If omitted, uses default (~/.pi/agent/sessions/<encoded-cwd>/).
*/
static continueRecent(cwd, sessionDir) {
const dir = sessionDir ? normalizePath(sessionDir) : getDefaultSessionDir(cwd);
const filterCwd = sessionDir !== undefined && dir !== getDefaultSessionDirPath(cwd);
const mostRecent = findMostRecentSession(dir, filterCwd ? cwd : undefined);
if (mostRecent) {
return new SessionManager(cwd, dir, mostRecent, true);
}
return new SessionManager(cwd, dir, undefined, true);
}
/** Create an in-memory session (no file persistence) */
static inMemory(cwd = process.cwd(), options) {
return new SessionManager(cwd, "", undefined, false, options);
}
/**
* Fork a session from another project directory into the current project.
* Creates a new session in the target cwd with the full history from the source session.
* @param sourcePath Path to the source session file
* @param targetCwd Target working directory (where the new session will be stored)
* @param sessionDir Optional session directory. If omitted, uses default for targetCwd.
*/
static forkFrom(sourcePath, targetCwd, sessionDir, options) {
const resolvedSourcePath = resolvePath(sourcePath);
const resolvedTargetCwd = resolvePath(targetCwd);
const sourceEntries = loadEntriesFromFile(resolvedSourcePath);
if (sourceEntries.length === 0) {
throw new Error(`Cannot fork: source session file is empty or invalid: ${resolvedSourcePath}`);
}
const sourceHeader = sourceEntries.find((e) => e.type === "session");
if (!sourceHeader) {
throw new Error(`Cannot fork: source session has no header: ${resolvedSourcePath}`);
}
const dir = sessionDir ? normalizePath(sessionDir) : getDefaultSessionDir(resolvedTargetCwd);
if (!existsSync(dir)) {
mkdirSync(dir, { recursive: true });
}
// Create new session file with new ID but forked content
if (options?.id !== undefined) {
assertValidSessionId(options.id);
}
const newSessionId = options?.id ?? createSessionId();
const timestamp = new Date().toISOString();
const fileTimestamp = timestamp.replace(/[:.]/g, "-");
const newSessionFile = join(dir, `${fileTimestamp}_${newSessionId}.jsonl`);
// Write new header pointing to source as parent, with updated cwd
const newHeader = {
type: "session",
version: CURRENT_SESSION_VERSION,
id: newSessionId,
timestamp,
cwd: resolvedTargetCwd,
parentSession: resolvedSourcePath,
};
writeFileSync(newSessionFile, `${JSON.stringify(newHeader)}\n`, { flag: "wx" });
// Copy all non-header entries from source
for (const entry of sourceEntries) {
if (entry.type !== "session") {
appendFileSync(newSessionFile, `${JSON.stringify(entry)}\n`);
}
}
return new SessionManager(resolvedTargetCwd, dir, newSessionFile, true);
}
/**
* List all sessions for a directory.
* @param cwd Working directory (used to compute default session directory)
* @param sessionDir Optional session directory. If omitted, uses default (~/.pi/agent/sessions/<encoded-cwd>/).
* @param onProgress Optional callback for progress updates (loaded, total)
*/
static async list(cwd, sessionDir, onProgress) {
const dir = sessionDir ? normalizePath(sessionDir) : getDefaultSessionDir(cwd);
const filterCwd = sessionDir !== undefined && dir !== getDefaultSessionDirPath(cwd);
const resolvedCwd = resolvePath(cwd);
const sessions = (await listSessionsFromDir(dir, onProgress)).filter((session) => !filterCwd || sessionCwdMatches(session.cwd, resolvedCwd));
sessions.sort((a, b) => b.modified.getTime() - a.modified.getTime());
return sessions;
}
static async listAll(sessionDirOrOnProgress, onProgress) {
const customSessionDir = typeof sessionDirOrOnProgress === "string" ? normalizePath(sessionDirOrOnProgress) : undefined;
const progress = typeof sessionDirOrOnProgress === "function" ? sessionDirOrOnProgress : onProgress;
if (customSessionDir) {
const sessions = await listSessionsFromDir(customSessionDir, progress);
sessions.sort((a, b) => b.modified.getTime() - a.modified.getTime());
return sessions;
}
const sessionsDir = getSessionsDir();
try {
if (!existsSync(sessionsDir)) {
return [];
}
const entries = await readdir(sessionsDir, { withFileTypes: true });
const dirs = entries.filter((e) => e.isDirectory()).map((e) => join(sessionsDir, e.name));
// Count total files first for accurate progress
let totalFiles = 0;