#!/usr/bin/env node
import { createReadStream } from "node:fs";
import { promises as fs } from "node:fs";
import { homedir } from "node:os";
import path from "node:path";
import { createInterface } from "node:readline";
const DEFAULT_SESSIONS_DIR = path.join(homedir(), ".pi/agent/sessions");
const MODELS_GENERATED_PATH = path.join(process.cwd(), "packages/ai/src/models.generated.ts");
const MODELS_CONFIG_PATH = path.join(homedir(), ".pi/agent/models.json");
const REPORT_TIME_ZONE = "Europe/Berlin";
const CHART_WIDTH = 40;
function parseArgs(argv) {
const options = { sessionsDir: DEFAULT_SESSIONS_DIR, json: false, text: false, allSessions: false, since: undefined, modelFilter: undefined, modelPrefixes: [], bashContains: [], cwd: process.cwd(), help: false };
for (let i = 0; i < argv.length; i++) {
const arg = argv[i];
if (arg === "--help" || arg === "-h") options.help = true;
else if (arg === "--json") options.json = true;
else if (arg === "--text") options.text = true;
else if (arg === "--sessions-dir") options.sessionsDir = argv[++i];
else if (arg === "--since") options.since = argv[++i];
else if (arg === "--all-sessions") options.allSessions = true;
else if (arg === "--model") options.modelFilter = argv[++i];
else if (arg === "--model-prefix") options.modelPrefixes.push(argv[++i]);
else if (arg === "--bash-contains") options.bashContains.push(argv[++i]);
else if (arg === "--git-commit-or-push") options.bashContains.push("git commit", "git push");
else if (arg === "--cwd") options.cwd = argv[++i];
else if (arg === "--all-cwds") options.cwd = undefined;
else throw new Error(`Unknown argument: ${arg}`);
}
return options;
}
function printHelp() {
console.log(`Usage: node scripts/session-context-stats.mjs [options]
Options:
--sessions-dir <path> Sessions directory (default: ~/.pi/agent/sessions)
--model <substring> Filter provider/model by substring
--model-prefix <p> Include provider/model prefixes, repeatable, e.g. openai-codex/
--bash-contains <text> Include only sessions with bash tool calls containing text, repeatable
--git-commit-or-push Shortcut for --bash-contains "git commit" --bash-contains "git push"
--cwd <path> Include only sessions whose cwd is this path (default: current cwd)
--all-cwds Include sessions from all cwd values
--since <iso> Only scan session files created at or after this ISO time
--all-sessions Scan all sessions (default already scans all)
--json Print JSON instead of HTML report
--text Print plain text instead of HTML report
-h, --help Show this help
`);
}
function parseSessionFileTimestamp(sessionFile) {
const rawTimestamp = path.basename(sessionFile).split("_")[0];
if (!rawTimestamp) return null;
const ms = Date.parse(rawTimestamp.replace(/T(\d{2})-(\d{2})-(\d{2})-(\d{3})Z$/, "T$1:$2:$3.$4Z"));
return Number.isFinite(ms) ? ms : null;
}
function getTimeZoneParts(ms) {
const parts = new Intl.DateTimeFormat("en-CA", {
timeZone: REPORT_TIME_ZONE,
year: "numeric",
month: "2-digit",
day: "2-digit",
}).formatToParts(new Date(ms));
return Object.fromEntries(parts.filter((part) => part.type !== "literal").map((part) => [part.type, part.value]));
}
function formatDay(ms) {
const parts = getTimeZoneParts(ms);
return `${parts.year}-${parts.month}-${parts.day}`;
}
function formatInt(value) {
return new Intl.NumberFormat("en-US").format(Math.round(value));
}
function formatNumber(value) {
return Number.isFinite(value) ? value.toFixed(2) : "n/a";
}
function formatPercent(value) {
return Number.isFinite(value) ? `${value.toFixed(1)}%` : "n/a";
}
function bar(percent) {
const clamped = Number.isFinite(percent) ? Math.max(0, Math.min(100, percent)) : 0;
const filled = Math.round((clamped / 100) * CHART_WIDTH);
return `${"█".repeat(filled)}${"░".repeat(CHART_WIDTH - filled)}`;
}
function median(values) {
const finite = values.filter((value) => Number.isFinite(value)).sort((a, b) => a - b);
if (finite.length === 0) return null;
const middle = Math.floor(finite.length / 2);
return finite.length % 2 === 0 ? (finite[middle - 1] + finite[middle]) / 2 : finite[middle];
}
async function* walkJsonlFiles(dir) {
const entries = await fs.readdir(dir, { withFileTypes: true });
entries.sort((a, b) => a.name.localeCompare(b.name));
for (const entry of entries) {
const fullPath = path.join(dir, entry.name);
if (entry.isDirectory()) yield* walkJsonlFiles(fullPath);
else if (entry.isFile() && entry.name.endsWith(".jsonl")) yield fullPath;
}
}
async function loadContextWindows() {
const windows = new Map();
const sources = [];
let text = "";
try {
text = await fs.readFile(MODELS_GENERATED_PATH, "utf8");
sources.push(MODELS_GENERATED_PATH);
} catch {
// Optional in non-repo usage.
}
const providerRegex = /\n\t"([^"]+)": \{([\s\S]*?\n\t)\},/g;
let providerMatch;
while ((providerMatch = providerRegex.exec(text)) !== null) {
const provider = providerMatch[1];
const body = providerMatch[2];
const modelRegex = /\n\t\t"([^"]+)": \{[\s\S]*?contextWindow: (\d+),/g;
let modelMatch;
while ((modelMatch = modelRegex.exec(body)) !== null) {
windows.set(`${provider}/${modelMatch[1]}`, Number(modelMatch[2]));
}
}
try {
const config = JSON.parse(await fs.readFile(MODELS_CONFIG_PATH, "utf8"));
sources.push(MODELS_CONFIG_PATH);
const providers = config?.providers && typeof config.providers === "object" ? config.providers : {};
for (const [providerName, provider] of Object.entries(providers)) {
const overrides = provider?.modelOverrides && typeof provider.modelOverrides === "object" ? provider.modelOverrides : {};
for (const [modelId, override] of Object.entries(overrides)) {
if (typeof override?.contextWindow === "number") windows.set(`${providerName}/${modelId}`, override.contextWindow);
}
if (Array.isArray(provider?.models)) {
for (const model of provider.models) {
if (typeof model?.id === "string" && typeof model.contextWindow === "number") windows.set(`${providerName}/${model.id}`, model.contextWindow);
}
}
}
} catch {
// Optional user config.
}
return { windows, sources };
}
function contextTokens(usage) {
if (!usage || typeof usage !== "object") return null;
const totalTokens = Number(usage.totalTokens ?? 0);
if (Number.isFinite(totalTokens) && totalTokens > 0) return totalTokens;
const input = Number(usage.input ?? 0);
const output = Number(usage.output ?? 0);
const cacheRead = Number(usage.cacheRead ?? 0);
const cacheWrite = Number(usage.cacheWrite ?? 0);
const value = input + output + cacheRead + cacheWrite;
return Number.isFinite(value) && value > 0 ? value : null;
}
async function scanSessions(sessionsDir, sinceMs, contextWindows, cwdFilter) {
const windows = contextWindows.windows;
const sessions = [];
const meta = { sessionsDir, sessionFilesScanned: 0, sessionFilesIncluded: 0, sessionFilesSkippedOlderThanSince: 0, malformedLines: 0 };
for await (const sessionFile of walkJsonlFiles(sessionsDir)) {
meta.sessionFilesScanned++;
const fileTimestampMs = parseSessionFileTimestamp(sessionFile);
if (sinceMs !== null && fileTimestampMs !== null && fileTimestampMs < sinceMs) {
meta.sessionFilesSkippedOlderThanSince++;
continue;
}
meta.sessionFilesIncluded++;
const session = {
sessionFile,
cwd: null,
startMs: fileTimestampMs ?? 0,
endMs: fileTimestampMs ?? 0,
providerModel: "[unknown]/[unknown]",
assistantMessages: 0,
userMessages: 0,
compactions: 0,
seenCompaction: false,
maxPromptTokens: null,
preFirstCompactionTokens: null,
maxContextUsagePercent: null,
preFirstCompactionUsagePercent: null,
contextWindow: null,
bashCommands: [],
over80: false,
over90: false,
over100: false,
};
const input = createReadStream(sessionFile, { encoding: "utf8" });
const rl = createInterface({ input, crlfDelay: Infinity });
for await (const line of rl) {
if (!line.trim()) continue;
let entry;
try {
entry = JSON.parse(line);
} catch {
meta.malformedLines++;
continue;
}
if (entry.type === "session" && typeof entry.cwd === "string") session.cwd = entry.cwd;
const entryMs = Date.parse(entry.timestamp ?? "");
if (Number.isFinite(entryMs)) {
if (!session.startMs || entryMs < session.startMs) session.startMs = entryMs;
if (!session.endMs || entryMs > session.endMs) session.endMs = entryMs;
}
if (entry.type === "compaction") {
session.compactions++;
if (typeof entry.tokensBefore === "number") {
session.maxPromptTokens = Math.max(session.maxPromptTokens ?? 0, entry.tokensBefore);
if (!session.seenCompaction) session.preFirstCompactionTokens = entry.tokensBefore;
}
session.seenCompaction = true;
continue;
}
if (entry.type !== "message" || !entry.message) continue;
const message = entry.message;
if (message.role === "assistant" && Array.isArray(message.content)) {
for (const block of message.content) {
if (block?.type !== "toolCall" || block.name !== "bash") continue;
const command = typeof block.arguments?.command === "string" ? block.arguments.command : "";
if (command) session.bashCommands.push(command);
}
}
if (message.role === "user") session.userMessages++;
if (message.role !== "assistant") continue;
session.assistantMessages++;
const provider = typeof message.provider === "string" ? message.provider : "[unknown]";
const model = typeof message.model === "string" ? message.model : "[unknown]";
session.providerModel = `${provider}/${model}`;
const contextWindow = windows.get(session.providerModel) ?? null;
if (contextWindow !== null) session.contextWindow = contextWindow;
const tokens = contextTokens(message.usage);
if (tokens !== null) {
session.maxPromptTokens = Math.max(session.maxPromptTokens ?? 0, tokens);
if (!session.seenCompaction) session.preFirstCompactionTokens = tokens;
}
}
if (session.maxPromptTokens !== null && session.contextWindow !== null) {
session.maxContextUsagePercent = (session.maxPromptTokens / session.contextWindow) * 100;
session.over80 = session.maxContextUsagePercent >= 80;
session.over90 = session.maxContextUsagePercent >= 90;
session.over100 = session.maxContextUsagePercent >= 100;
}
if (session.preFirstCompactionTokens !== null && session.contextWindow !== null) {
session.preFirstCompactionUsagePercent = (session.preFirstCompactionTokens / session.contextWindow) * 100;
}
if (!cwdFilter || path.resolve(session.cwd ?? "") === cwdFilter) sessions.push(session);
}
return { sessions, meta };
}
function summarizeGroups(sessions, keyFn) {
const groups = new Map();
for (const session of sessions) {
const key = keyFn(session);
if (!groups.has(key)) groups.set(key, []);
groups.get(key).push(session);
}
return [...groups.entries()].map(([key, group]) => summarizeSessionGroup(key, group)).sort((a, b) => a.key.localeCompare(b.key));
}
function summarizeSessionGroup(key, group) {
const withUsage = group.filter((session) => session.maxContextUsagePercent !== null);
const withTokens = group.filter((session) => session.maxPromptTokens !== null);
const withPreCompactionUsage = group.filter((session) => session.preFirstCompactionUsagePercent !== null);
const compactions = group.filter((session) => session.compactions > 0).length;
const totalCompactions = group.reduce((sum, session) => sum + session.compactions, 0);
const contextWindows = [...new Set(group.map((session) => session.contextWindow).filter((value) => value !== null))].sort((a, b) => a - b);
return {
key,
sessions: group.length,
contextWindows,
assistantMessages: group.reduce((sum, session) => sum + session.assistantMessages, 0),
avgTurns: group.reduce((sum, session) => sum + session.userMessages, 0) / group.length,
avgDurationMinutes: group.reduce((sum, session) => sum + Math.max(0, session.endMs - session.startMs) / 60000, 0) / group.length,
avgMaxPromptTokens: withTokens.length === 0 ? null : withTokens.reduce((sum, session) => sum + (session.maxPromptTokens ?? 0), 0) / withTokens.length,
medianMaxPromptTokens: median(withTokens.map((session) => session.maxPromptTokens)),
avgMaxContextUsagePercent: withUsage.length === 0 ? null : withUsage.reduce((sum, session) => sum + (session.maxContextUsagePercent ?? 0), 0) / withUsage.length,
medianMaxContextUsagePercent: median(withUsage.map((session) => session.maxContextUsagePercent)),
medianPreFirstCompactionUsagePercent: median(withPreCompactionUsage.map((session) => session.preFirstCompactionUsagePercent)),
contextKnownSessions: withUsage.length,
sessionsWithCompaction: compactions,
totalCompactions,
compactionRate: (compactions / group.length) * 100,
over80: group.filter((session) => session.over80).length,
over90: group.filter((session) => session.over90).length,
over100: group.filter((session) => session.over100).length,
};
}
function buildSummary(sessions, meta, options) {
const lowerPrefixes = options.modelPrefixes.map((prefix) => prefix.toLowerCase());
const bashContains = options.bashContains.map((text) => text.toLowerCase());
const filtered = sessions.filter((session) => {
const providerModel = session.providerModel.toLowerCase();
if (options.modelFilter && !providerModel.includes(options.modelFilter.toLowerCase())) return false;
if (lowerPrefixes.length > 0 && !lowerPrefixes.some((prefix) => providerModel.startsWith(prefix))) return false;
if (bashContains.length > 0) {
const commands = session.bashCommands.map((command) => command.toLowerCase());
if (!bashContains.some((text) => commands.some((command) => command.includes(text)))) return false;
}
return true;
});
return {
filters: { model: options.modelFilter ?? null, modelPrefixes: options.modelPrefixes, bashContains: options.bashContains, cwd: options.cwd ? path.resolve(options.cwd) : null },
scan: { ...meta, timezone: REPORT_TIME_ZONE },
totals: summarizeSessionGroup("total", filtered),
byDay: summarizeGroups(filtered, (session) => formatDay(session.startMs)),
byModel: summarizeGroups(filtered, (session) => session.providerModel).sort((a, b) => b.sessions - a.sessions || a.key.localeCompare(b.key)),
byModelDay: summarizeGroups(filtered, (session) => session.providerModel).sort((a, b) => b.sessions - a.sessions || a.key.localeCompare(b.key)).map((model) => ({
...model,
byDay: summarizeGroups(
filtered.filter((session) => session.providerModel === model.key),
(session) => formatDay(session.startMs)
),
})),
};
}
function lineForGroup(group, indent = " ") {
return `${indent}${group.key} sessions=${formatInt(group.sessions).padStart(4)} avgTurns=${formatNumber(group.avgTurns).padStart(5)} avgMin=${formatNumber(group.avgDurationMinutes).padStart(6)} avgMaxTok=${group.avgMaxPromptTokens === null ? "n/a" : formatInt(group.avgMaxPromptTokens).padStart(7)} medMaxCtx=${group.medianMaxContextUsagePercent === null ? "n/a" : formatPercent(group.medianMaxContextUsagePercent).padStart(6)} medPreCompactCtx=${group.medianPreFirstCompactionUsagePercent === null ? "n/a" : formatPercent(group.medianPreFirstCompactionUsagePercent).padStart(6)} avgCtx=${group.avgMaxContextUsagePercent === null ? "n/a" : formatPercent(group.avgMaxContextUsagePercent).padStart(6)} compact=${formatPercent(group.compactionRate).padStart(6)} over90=${formatInt(group.over90).padStart(3)} ${bar(group.medianMaxContextUsagePercent ?? 0)}`;
}
function buildTextReport(summary) {
const lines = [];
lines.push(`Scanned ${formatInt(summary.scan.sessionFilesIncluded)} session files in ${summary.scan.sessionsDir}`);
lines.push(`Report timezone: ${summary.scan.timezone} (CET/CEST)`);
lines.push(`Context window sources: ${summary.scan.contextWindowSources.join(", ") || "none"}`);
if (summary.filters.model) lines.push(`Filters: model contains "${summary.filters.model}"`);
if (summary.filters.modelPrefixes.length > 0) lines.push(`Filters: model prefixes = ${summary.filters.modelPrefixes.join(", ")}`);
if (summary.filters.bashContains.length > 0) lines.push(`Filters: bash contains any of = ${summary.filters.bashContains.join(", ")}`);
if (summary.filters.cwd) lines.push(`Filters: cwd = ${summary.filters.cwd}`);
lines.push("Context usage parses full session JSONL files. max context uses max assistant usage.totalTokens per session, falling back to input + output + cacheRead + cacheWrite, plus compaction tokensBefore. medPreCompactCtx uses the last assistant usage before the first compaction, or the first compaction tokensBefore when present, divided by model contextWindow from packages/ai/src/models.generated.ts when known.");
lines.push("");
lines.push("Totals");
lines.push(lineForGroup(summary.totals));
lines.push("");
lines.push("By day");
for (const group of summary.byDay) lines.push(lineForGroup(group));
lines.push("");
lines.push("By model");
for (const group of summary.byModel) lines.push(lineForGroup(group));
lines.push("");
lines.push("By model, then by day");
for (const model of summary.byModelDay) {
lines.push("");
const contextWindowLabel = model.contextWindows.length === 0 ? "unknown" : model.contextWindows.map((value) => formatInt(value)).join(", ");
lines.push(`${model.key} contextWindow=${contextWindowLabel}`);
lines.push(lineForGroup(model, " total "));
for (const group of model.byDay) lines.push(lineForGroup(group, " "));
}
if (summary.scan.malformedLines > 0) {
lines.push("");
lines.push(`Malformed lines skipped: ${formatInt(summary.scan.malformedLines)}`);
}
return `${lines.join("\n")}\n`;
}
function escapeHtml(text) {
return text.replaceAll("&", "&").replaceAll("<", "<").replaceAll(">", ">");
}
function printHtmlReport(summary) {
console.log(`<!doctype html>
<meta charset="utf-8">
<title>Session context stats</title>
<style>
body { margin: 24px; background: #fff; color: #111; }
pre { font: 13px/1.35 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; white-space: pre; }
</style>
<pre>${escapeHtml(buildTextReport(summary))}</pre>`);
}
async function main() {
const options = parseArgs(process.argv.slice(2));
if (options.help) {
printHelp();
return;
}
const sinceMs = options.since ? Date.parse(options.since) : null;
if (options.since && !Number.isFinite(sinceMs)) throw new Error(`Invalid --since value: ${options.since}`);
const contextWindows = await loadContextWindows();
const cwdFilter = options.cwd ? path.resolve(options.cwd) : undefined;
const { sessions, meta } = await scanSessions(path.resolve(options.sessionsDir), sinceMs, contextWindows, cwdFilter);
const summary = buildSummary(sessions, { ...meta, contextWindowSources: contextWindows.sources }, options);
if (options.json) console.log(JSON.stringify(summary, null, 2));
else if (options.text) console.log(buildTextReport(summary));
else printHtmlReport(summary);
}
main().catch((error) => {
console.error(error instanceof Error ? error.message : String(error));
process.exit(1);
});