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bare-operating-system/packages/bare-os-coreutils/lib/agent-compact.js
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Raven Scott 64619d5bc2
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2026-07-31 21:08:43 -04:00

545 lines
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JavaScript

/**
* Advanced context-window compaction for /bin/agent.
* Tiered rollover: shrink fat tool payloads → digest older turns →
* rolling summary message → hard trim fallback.
*/
/**
* @param {unknown} value
*/
function bareAgentCompactEstimateTokens(value) {
if (typeof bareAgentEstimateTokens === 'function') {
return bareAgentEstimateTokens(value)
}
try {
return Math.max(0, Math.ceil(JSON.stringify(value == null ? '' : value).length / 4))
} catch {
return 0
}
}
/**
* @param {unknown} msg
* @returns {string}
*/
function bareAgentMessagePlainText(msg) {
if (!msg || typeof msg !== 'object') return ''
const m = /** @type {Record<string, unknown>} */ (msg)
const c = m.content
if (typeof c === 'string') return c
if (Array.isArray(c)) {
/** @type {string[]} */
const parts = []
for (const part of c) {
if (typeof part === 'string') parts.push(part)
else if (part && typeof part === 'object') {
const p = /** @type {Record<string, unknown>} */ (part)
if (typeof p.text === 'string') parts.push(p.text)
else if (typeof p.content === 'string') parts.push(p.content)
}
}
return parts.join('\n')
}
if (m.tool_calls && Array.isArray(m.tool_calls)) {
/** @type {string[]} */
const names = []
for (const tc of m.tool_calls) {
if (!tc || typeof tc !== 'object') continue
const fn = /** @type {Record<string, unknown>} */ (tc).function
if (fn && typeof fn === 'object') {
const n = /** @type {Record<string, unknown>} */ (fn).name
if (typeof n === 'string' && n) names.push(n)
}
}
if (names.length) return 'tool_calls: ' + names.join(', ')
}
return ''
}
/**
* @param {string} s
* @param {number} max
*/
function bareAgentClipText(s, max) {
const t = String(s || '').replace(/\s+/g, ' ').trim()
if (t.length <= max) return t
if (max < 24) return t.slice(0, max)
const head = Math.floor(max * 0.62)
const tail = Math.max(8, max - head - 5)
return t.slice(0, head) + ' … ' + t.slice(-tail)
}
/**
* Shrink oversized tool / assistant payloads in-place (clone).
* @param {unknown[]} msgs
* @param {number} toolMaxChars
* @returns {unknown[]}
*/
function bareAgentShrinkFatMessages(msgs, toolMaxChars) {
const max = Math.max(240, Math.floor(toolMaxChars || 1600))
/** @type {unknown[]} */
const out = []
for (const msg of msgs) {
if (!msg || typeof msg !== 'object') {
out.push(msg)
continue
}
const m = /** @type {Record<string, unknown>} */ (msg)
const role = String(m.role || '')
if (role === 'tool' && typeof m.content === 'string' && m.content.length > max) {
out.push({
...m,
content:
bareAgentClipText(m.content, max) +
'\n[tool output compacted ' +
String(m.content.length) +
'→' +
String(max) +
' chars]'
})
continue
}
if (
(role === 'assistant' || role === 'user') &&
typeof m.content === 'string' &&
m.content.length > max * 4
) {
out.push({
...m,
content:
bareAgentClipText(m.content, max * 4) +
'\n[message compacted]'
})
continue
}
out.push(msg)
}
return out
}
/**
* Group chat into [system?] + turn groups (user | assistant+tools*).
* @param {unknown[]} msgs
* @returns {{ system: unknown | null, groups: unknown[][] }}
*/
function bareAgentGroupMessageTurns(msgs) {
/** @type {unknown | null} */
let system = null
/** @type {unknown[][]} */
const groups = []
/** @type {unknown[]} */
let cur = []
function flush() {
if (cur.length) {
groups.push(cur)
cur = []
}
}
for (const msg of Array.isArray(msgs) ? msgs : []) {
if (!msg || typeof msg !== 'object') continue
const role = String(/** @type {Record<string, unknown>} */ (msg).role || '')
if (role === 'system' && system == null && groups.length === 0 && !cur.length) {
system = msg
continue
}
if (role === 'user') {
flush()
cur = [msg]
continue
}
if (role === 'assistant' || role === 'tool') {
if (!cur.length) cur = [msg]
else cur.push(msg)
continue
}
// unknown roles — attach to current or solo group
if (!cur.length) cur = [msg]
else cur.push(msg)
}
flush()
return { system, groups }
}
/**
* True if message is a prior compaction summary we injected.
* @param {unknown} msg
*/
function bareAgentIsCompactionMessage(msg) {
if (!msg || typeof msg !== 'object') return false
const m = /** @type {Record<string, unknown>} */ (msg)
if (m.bare_os_compaction === true) return true
const c = typeof m.content === 'string' ? m.content : ''
return (
String(m.role || '') === 'user' &&
/^\[context compaction\]/i.test(c.trim())
)
}
/**
* One-line digest for a message (extractive).
* @param {unknown} msg
* @param {number} max
*/
function bareAgentDigestMessage(msg, max) {
if (!msg || typeof msg !== 'object') return ''
const m = /** @type {Record<string, unknown>} */ (msg)
const role = String(m.role || '?')
const text = bareAgentMessagePlainText(m)
if (role === 'tool') {
const name =
typeof m.name === 'string'
? m.name
: typeof m.tool_call_id === 'string'
? m.tool_call_id.slice(0, 12)
: 'tool'
return '- tool:' + name + ' ' + bareAgentClipText(text, Math.max(40, max - 24))
}
if (role === 'assistant') {
return '- assistant ' + bareAgentClipText(text || '(tools only)', max)
}
if (role === 'user') {
if (bareAgentIsCompactionMessage(m)) {
return '- prior-compaction ' + bareAgentClipText(text.replace(/^\[context compaction\][^\n]*\n?/i, ''), max)
}
return '- user ' + bareAgentClipText(text, max)
}
return '- ' + role + ' ' + bareAgentClipText(text, max)
}
/**
* Build a rolling summary from older turn groups.
* @param {unknown[][]} groups
* @param {{ maxChars?: number, perMsg?: number }} [opts]
*/
function bareAgentBuildCompactionSummary(groups, opts) {
const maxChars = Math.max(400, Math.floor((opts && opts.maxChars) || 3500))
const perMsg = Math.max(60, Math.floor((opts && opts.perMsg) || 180))
/** @type {string[]} */
const lines = [
'[context compaction] Older turns were summarized to fit the model context window. Preserve goals, paths, errors, and decisions below.',
''
]
let used = lines.join('\n').length
let kept = 0
for (const g of groups) {
/** @type {string[]} */
const block = []
for (const msg of g) {
const d = bareAgentDigestMessage(msg, perMsg)
if (d) block.push(d)
}
if (!block.length) continue
const chunk = block.join('\n') + '\n'
if (used + chunk.length > maxChars && kept > 0) {
lines.push('… (' + String(groups.length - kept) + ' older turns omitted)')
break
}
lines.push(chunk.trimEnd())
used += chunk.length
kept++
}
lines.push('')
lines.push(
'Continue from the recent messages after this summary. Prefer tools over guessing.'
)
let body = lines.join('\n')
if (body.length > maxChars) body = body.slice(0, maxChars - 20) + '\n… truncated'
return body
}
/**
* @param {unknown[]} msgs
* @param {number} ctxSize
* @param {{
* tools?: unknown[],
* reserveCompletion?: number,
* keepRecent?: number,
* toolMaxChars?: number,
* summaryMaxChars?: number,
* softRatio?: number,
* mode?: 'auto' | 'off' | 'aggressive'
* }} [opts]
* @returns {{
* messages: unknown[],
* meta: {
* compacted: boolean,
* mode: string,
* beforeTokens: number,
* afterTokens: number,
* budget: number,
* droppedGroups: number,
* tiers: string[]
* }
* }}
*/
function bareAgentCompactMessagesForCtx(msgs, ctxSize, opts) {
const modeRaw = String((opts && opts.mode) || 'auto').trim().toLowerCase()
const mode =
modeRaw === 'off' || modeRaw === 'aggressive' ? modeRaw : 'auto'
/** @type {string[]} */
const tiers = []
const ctx = Math.max(2048, Math.floor(Number(ctxSize) || 4096))
const reserve =
opts && Number.isFinite(Number(opts.reserveCompletion))
? Math.max(256, Math.floor(Number(opts.reserveCompletion)))
: Math.min(2048, Math.max(256, Math.floor(ctx * 0.12)))
const toolsTok = bareAgentCompactEstimateTokens(
opts && Array.isArray(opts.tools) && opts.tools.length ? opts.tools : []
)
const budget = Math.max(512, ctx - reserve - toolsTok)
const softRatio =
mode === 'aggressive'
? 0.7
: Math.min(0.95, Math.max(0.55, Number(opts && opts.softRatio) || 0.82))
const softBudget = Math.floor(budget * softRatio)
const keepRecentDefault = mode === 'aggressive' ? 4 : 8
let keepRecent = Math.max(
2,
Math.floor(
Number(opts && opts.keepRecent) > 0
? Number(opts.keepRecent)
: keepRecentDefault
)
)
const toolMax =
mode === 'aggressive'
? Math.min(900, Number(opts && opts.toolMaxChars) || 900)
: Math.max(400, Number(opts && opts.toolMaxChars) || 1600)
const summaryMax =
mode === 'aggressive'
? Math.min(2200, Number(opts && opts.summaryMaxChars) || 2200)
: Math.max(800, Number(opts && opts.summaryMaxChars) || 3500)
const input = Array.isArray(msgs) ? msgs.slice() : []
const beforeTokens = bareAgentCompactEstimateTokens(input)
if (mode === 'off') {
const trimmed =
typeof bareAgentTrimMessagesForCtx === 'function'
? bareAgentTrimMessagesForCtx(input, ctxSize, opts)
: input
return {
messages: trimmed,
meta: {
compacted: false,
mode,
beforeTokens,
afterTokens: bareAgentCompactEstimateTokens(trimmed),
budget,
droppedGroups: 0,
tiers: ['off']
}
}
}
/** @type {unknown[]} */
let out = bareAgentShrinkFatMessages(input, toolMax)
if (out !== input && bareAgentCompactEstimateTokens(out) < beforeTokens) {
tiers.push('shrink-tools')
}
// Already fits soft budget — keep light shrink only.
if (bareAgentCompactEstimateTokens(out) <= softBudget) {
return {
messages: out,
meta: {
compacted: tiers.length > 0,
mode,
beforeTokens,
afterTokens: bareAgentCompactEstimateTokens(out),
budget,
droppedGroups: 0,
tiers: tiers.length ? tiers : ['noop']
}
}
}
// Merge prior compaction blobs in the middle into the new summary.
const { system, groups } = bareAgentGroupMessageTurns(out)
let droppedGroups = 0
if (groups.length > keepRecent) {
const older = groups.slice(0, Math.max(0, groups.length - keepRecent))
const recent = groups.slice(Math.max(0, groups.length - keepRecent))
// Drop nested prior compaction-only groups from "older" but fold text in.
/** @type {unknown[][]} */
const olderFlat = []
for (const g of older) {
if (g.length === 1 && bareAgentIsCompactionMessage(g[0])) {
olderFlat.push(g)
} else olderFlat.push(g)
}
const summaryText = bareAgentBuildCompactionSummary(olderFlat, {
maxChars: summaryMax,
perMsg: mode === 'aggressive' ? 120 : 180
})
const summaryMsg = {
role: 'user',
content: summaryText,
bare_os_compaction: true
}
/** @type {unknown[]} */
const next = []
if (system) next.push(system)
next.push(summaryMsg)
for (const g of recent) for (const m of g) next.push(m)
out = next
droppedGroups = older.length
tiers.push('rolling-summary')
}
// Still over: reduce keepRecent iteratively.
let guard = 0
while (
bareAgentCompactEstimateTokens(out) > budget &&
keepRecent > 2 &&
guard < 8
) {
keepRecent--
guard++
const again = bareAgentGroupMessageTurns(out)
// Re-split: system + optional summary + recent
/** @type {unknown[][]} */
const gs = again.groups
// Find existing summary at start of groups
let start = 0
if (gs[0] && gs[0].length === 1 && bareAgentIsCompactionMessage(gs[0][0])) {
start = 1
}
const body = gs.slice(start)
if (body.length <= keepRecent) break
const older = body.slice(0, body.length - keepRecent)
const recent = body.slice(body.length - keepRecent)
const priorSummary =
start === 1 && gs[0] && gs[0][0]
? bareAgentMessagePlainText(gs[0][0])
: ''
const folded = priorSummary
? [
[
{
role: 'user',
content: priorSummary,
bare_os_compaction: true
}
],
...older
]
: older
const summaryText = bareAgentBuildCompactionSummary(folded, {
maxChars: summaryMax,
perMsg: 120
})
/** @type {unknown[]} */
const next = []
if (again.system) next.push(again.system)
next.push({
role: 'user',
content: summaryText,
bare_os_compaction: true
})
for (const g of recent) for (const m of g) next.push(m)
out = next
droppedGroups += older.length
tiers.push('tighten-keep=' + String(keepRecent))
}
// Hard fallback
if (bareAgentCompactEstimateTokens(out) > budget) {
tiers.push('hard-trim')
out =
typeof bareAgentTrimMessagesForCtx === 'function'
? bareAgentTrimMessagesForCtx(out, ctxSize, opts)
: out
}
const afterTokens = bareAgentCompactEstimateTokens(out)
return {
messages: out,
meta: {
compacted: tiers.some((t) => t !== 'noop'),
mode,
beforeTokens,
afterTokens,
budget,
droppedGroups,
tiers
}
}
}
/**
* Disk history compaction: shrink tools + optional rolling summary when huge.
* @param {unknown[]} msgs
* @param {number} maxBytes
* @param {{ keepRecent?: number }} [opts]
*/
function bareAgentCompactMessagesForDisk(msgs, maxBytes, opts) {
const cap = Math.max(20_000, Math.floor(maxBytes || 500_000))
let out = bareAgentShrinkFatMessages(
Array.isArray(msgs) ? msgs : [],
2400
)
if (JSON.stringify(out).length <= cap) return out
// Approximate tokens from byte budget (chars/4).
const approxCtx = Math.max(4096, Math.floor(cap / 4))
const packed = bareAgentCompactMessagesForCtx(out, approxCtx, {
mode: 'aggressive',
keepRecent: (opts && opts.keepRecent) || 12,
reserveCompletion: 256,
toolMaxChars: 1200,
summaryMaxChars: 6000
})
out = packed.messages
if (
typeof bareAgentTrimMessages === 'function' &&
JSON.stringify(out).length > cap
) {
out = bareAgentTrimMessages(out, cap)
}
return out
}
/**
* Resolve compaction settings from agent config + env.
* @param {Record<string, unknown>} cfg
* @param {Record<string, string>} [env]
*/
function bareAgentCompactionSettings(cfg, env) {
const e = env && typeof env === 'object' ? env : {}
const envMode = String(e.BARE_OS_AGENT_COMPACTION || '').trim().toLowerCase()
const cfgMode = String(
(cfg && cfg.context_compaction) || ''
)
.trim()
.toLowerCase()
let mode = envMode || cfgMode || 'auto'
if (mode !== 'off' && mode !== 'aggressive' && mode !== 'auto') mode = 'auto'
const keepRecent = Number(
e.BARE_OS_AGENT_COMPACTION_KEEP ||
(cfg && cfg.compaction_keep_recent) ||
0
)
const toolMaxChars = Number(
e.BARE_OS_AGENT_COMPACTION_TOOL_CHARS ||
(cfg && cfg.compaction_tool_chars) ||
0
)
return {
mode: /** @type {'auto'|'off'|'aggressive'} */ (mode),
keepRecent:
Number.isFinite(keepRecent) && keepRecent > 0
? Math.min(32, Math.floor(keepRecent))
: undefined,
toolMaxChars:
Number.isFinite(toolMaxChars) && toolMaxChars > 0
? Math.min(8000, Math.floor(toolMaxChars))
: undefined
}
}