eve/dist/src/harness/compaction.js

Filesystem-first framework for durable backend AI agents that run anywhere.

import{generateText}from"ai";import{estimateTokens}from"#harness/token-estimate.js";import{COMPACTION_CHECKPOINT_MARKER,COMPACTION_PROMPT_ENVELOPE,COMPACTION_RESUMPTION_MESSAGE,TODO_COMPACTION_PRESERVATION_LABEL,TRANSCRIPT_PAYLOAD_LIMIT,createCompactionPrompt}from"#harness/compaction-prompt.js";const COMPACTION_PROMPT_OVERHEAD_TOKENS=estimateTokens([{content:COMPACTION_PROMPT_ENVELOPE.system,role:`system`},{content:COMPACTION_PROMPT_ENVELOPE.prompt,role:`user`}]);function getInputTokenCount(e,n){let r=n.lastKnownInputTokens,i=n.lastKnownPromptMessageCount;return r===void 0||i===void 0||!Number.isInteger(i)||i<0||i>e.length?estimateTokens(e):r+estimateTokens(e.slice(i))}function shouldCompact(e,t){return e.length>0&&getInputTokenCount(e,t)+COMPACTION_PROMPT_OVERHEAD_TOKENS>t.threshold}async function resolveCompactionModel(e){let t=e.compactionModelReference??e.modelReference;return{model:t===e.modelReference?e.model:await e.resolveModel(t),providerOptions:t.providerOptions}}const COMPACTION_HEURISTICS=[toolResultCapHeuristic];function toolResultCapHeuristic(e){let t=withResumptionGuard([...e.previousCheckpoint===void 0?[]:[{content:COMPACTION_CHECKPOINT_MARKER,role:`user`},{content:e.previousCheckpoint,role:`assistant`}],...capToolResults(e.older),...e.recent],e.conversation);return evaluateThreshold(t,e.config,`should-compact`).type===`within-limit`?{messages:t,type:`within-limit`}:{type:`insufficient`}}function evaluateThreshold(e,n,r){let i=r===`should-compact`?COMPACTION_PROMPT_OVERHEAD_TOKENS:0,a=estimateTokens(e)+i;return{estimatedTokens:a,type:a<=n.threshold?`within-limit`:`over-limit`}}async function compactMessages(t,r,i,a,o,c,u){let{conversation:d,previousCheckpoint:f}=extractPreviousCheckpoint(t),p=selectRecentWindowSize(d,i);{let{older:e,recent:t}=splitMessagesForCompaction(d,p);if(e.length===0&&f===void 0)return keepNonToolResultMessages(t);for(let n of COMPACTION_HEURISTICS){let r=n({config:i,conversation:d,older:e,previousCheckpoint:f,recent:t});if(r.type===`within-limit`)return r.messages}}for(;;){let{older:t,recent:l}=splitMessagesForCompaction(d,p),m=createCompactionPrompt({messages:t,previousCheckpoint:f,transcriptBudgetTokens:i.threshold}),h=await generateText({abortSignal:u,headers:c,model:r,prompt:m.prompt,providerOptions:a,system:m.system,telemetry:o?{...o,functionId:`eve.compaction`}:void 0,temperature:0}),g=[{content:COMPACTION_CHECKPOINT_MARKER,role:`user`},{content:h.text,role:`assistant`}],_=withResumptionGuard([...g,...l],d);if(evaluateThreshold(_,i,`estimate`).type===`within-limit`)return _;let v=withResumptionGuard([...g,...keepNonToolResultMessages(l)],d);if(evaluateThreshold(v,i,`estimate`).type===`within-limit`||p===0)return v;--p}}function capToolResults(e){return e.map(e=>{if(e.role!==`tool`||typeof e.content==`string`)return e;let t=!1,n=e.content.map(e=>{if(e.type!==`tool-result`)return e;let n=JSON.stringify(e.output)??``;return n.length<=TRANSCRIPT_PAYLOAD_LIMIT?e:(t=!0,{...e,output:{type:`text`,value:`[Truncated by eve: tool result reduced during context compaction. Re-run the tool if you need the full output.]\n\n${n.slice(0,TRANSCRIPT_PAYLOAD_LIMIT)}`}})});return t?{...e,content:n}:e})}function withResumptionGuard(e,t){let n=e.at(-1)?.role;if(n!==void 0&&n!==`assistant`)return e;let r=findLastRealUserMessage(t),a=r!==void 0&&e.some(e=>e.role===`user`&&e.content===r.content);return[...e,r!==void 0&&!a?r:{content:COMPACTION_RESUMPTION_MESSAGE,role:`user`}]}function findLastRealUserMessage(e){for(let t=e.length-1;t>=0;--t){let r=e[t];if(!(r?.role!==`user`||typeof r.content!=`string`)&&!(r.content===COMPACTION_RESUMPTION_MESSAGE||r.content===COMPACTION_CHECKPOINT_MARKER||r.content.startsWith(TODO_COMPACTION_PRESERVATION_LABEL)))return r}}function extractPreviousCheckpoint(e){let t=e[0],r=e[1];return t?.role!==`user`||t.content!==COMPACTION_CHECKPOINT_MARKER||r?.role!==`assistant`?{conversation:[...e],previousCheckpoint:void 0}:{conversation:e.slice(2),previousCheckpoint:assistantMessageText(r)}}function keepNonToolResultMessages(e){let t=[];for(let n of e)if(n.role!==`tool`){if(n.role===`assistant`){let e=assistantMessageText(n);e.length>0&&t.push({content:e,role:`assistant`});continue}t.push(n)}return t}function assistantMessageText(e){return typeof e.content==`string`?e.content.trim():e.content.filter(e=>e.type===`text`).map(e=>e.text).join(``).trim()}function selectRecentWindowSize(e,n){let r=Math.min(n.recentWindowSize,Math.max(e.length-1,0)),i=resolveCompactionSummaryReserve(n),a=0,o=0;for(let s=e.length-1;s>=0&&a<r;--s){let r=e[s];if(r===void 0)continue;let c=estimateTokens([r]);if(o+c+i>n.threshold)break;o+=c,a+=1}return a}function resolveCompactionSummaryReserve(e){return Math.min(2048,Math.max(64,Math.floor(e.threshold/4)))}function splitMessagesForCompaction(e,t){if(t<=0)return{older:[...e],recent:[]};let n=e.length-t;for(;n<e.length&&e[n]?.role===`tool`;)n+=1;return{older:e.slice(0,n),recent:e.slice(n)}}export{compactMessages,getInputTokenCount,resolveCompactionModel,shouldCompact};