OpenCode 2.0 (6 minute read)

# OpenCode 2.0 Source: [https://anoma.ly/notes/opencode-2-0/](https://anoma.ly/notes/opencode-2-0/) OpenCode2\.0isamajoroverhaul\.Itdrawsonmillionsofdailyusers'experiencetodeliverasystemthatcanflextoeverythinganagentneedstobe\.Therearequitealotofnewfeatures,performanceimprovements,andbugfixesbutherearesomeofthemoreimpactfuluser\-facingchanges\. ## The Service FromthebeginningOpenCodeadoptedaclient/servermodel\.However,thiswasnotsomethingittookadvantageofbydefaultandwasmostlyusedbypowerusers\. In2\.0thisservernowautomaticallyrunsasasinglebackgroundprocessonyourmachine\.WhenyouopenupaTUI,thewebinterfaceorthedesktopappthey'realltalkingtothesamecentralprocess\. opencodepid48213Running Sessions Ifyou'reusingtheprogrammaticclient`@opencode/client`tomakeyourownscripts,theywillautodiscoverthelocalserviceandjustwork\.Thisisparticularlyusefulforscheduledtasks\.YoucanalsocallitviaCLIbyusing`opencode``api`commands\. Youcanexposeittootherhostsandrun`/pair`or`opencode``pair`toconnectittootherapplications\.Wehavenativeappsintheworksthattakeadvantageofthisflow\. ## The API TheoldAPIgrewhaphazardlyasweandtheworldcollectivelylearnedwhatagentsareandshouldbe\.Itwasbad\. WestartedfromscratchandexaminedalltheweirdusecasesacrossthemillionsofuserswhouseOpenCodeeveryday\.Itnowsupportsnearlyanythingyouneedtobeabletodo\. OpenCodeisalsoawareofitsownAPIandwillcallittodousefulthingslikemovingthecurrentsessionintoagitworktreewhenstartingnewwork\. SessionNew session OpenCode Fix flaky upload testinterrupted Migrate config loadertab closed We'vealsoshippedanewclientpackage`@opencode/client`thatcontainsclientsforvanillaJavaScriptaswellasEffect\. review\.ts``` import { OpenCode } from "@opencode/client" import { Service } from "@opencode/client/service" const endpoint = await Service.ensure() const client = OpenCode.make({ baseUrl: endpoint.url, headers: Service.headers(endpoint), }) const session = await client.session.create({ location: { directory: process.cwd() }, }) await client.session.prompt({ sessionID: session.id, text: "Review the current changes", }) ``` ## Code Mode ThemodelslovetowritecodeandOpenCode2\.0takesadvantageofthatmorethananyothercodingagent\.We'vebuiltaminimalJavaScriptinterpreterinthe`@opencode/codemode`package\. Session Code Mode MCP servers ThispackageingestsMCPserversorOpenAPIendpoints,convertingthemintofunctionsthattheagentcancallinascript\.ItcanrunthesescriptsnativelywithoutthecomplexityofNode\.jsVMsorembeddingcomplicatedsolutionslikeQuickJS\. Thisletsyouragentwritescriptsthatcandothingslikecallatool,mapovertheresultsandcallanothertool\.Singleroundtripinsteadofcallingthemoneatatime\. AllMCPserversin2\.0areoptedintocodemodebydefault\.Thismeansyoucanaddathousandofthemwithminimalcontextbloatandyouragentwilldiscoverandcomposethemtogetthingsdone\. ## Background Tasks Thelatestbatchofmodelsareincrediblygoodatorchestrationanditisimportantforharnessestoletthemexpressthefullextentofthatcapability\. First,we'veaddedbackgroundsubagents\.Thisallowstheprimaryagenttokickoffsomeworktoanotheronewhileitcontinues\. Thishappensautomaticallybutyoucanalsotriggeritmanually\-evenwithadifferentmodel\.Itletsyoudothingslike“spawnabackgroundfablesubagenttoreviewthiscode”whileyoukeepprompting\. Second,we'veaddedbackgroundshellcommands\.Theshelltoolcanbeinvokedasynchronouslysolong\-runningworkdoesnothavetoblocktheprimaryagent\.It'llbenotifiedwhenthingsarecomplete\. Ifanyforegroundshellcommandorsubagenttakeslongerthanyouexpect,youcanhitahotkeytomovethemtothebackgroundsoyoucankeepprompting\. ## Plugins AlthoughOpenCode1\.0hadapluginsystem,itnevergottheattentionitneeded\.Tocorrectthat,weforcedourselvestoimplementnearlyeveryOpenCode2\.0featureasaninternalpluginandtherearenow80\+ofthem\.ThisguaranteesthatthePluginAPIstayswellmaintained\. We'vealsopromotedTUIpluginsfromexperimentaltostable\.SinceitisallpoweredbyOpenTUI,youcanbuildnearlyanything\.Hereisanexampleofsomethinguseless\. WealsospentquitealotoftimeensuringeverythinginOpenCode2\.0canbehot\-reloaded\.Soitcanwriteapluginforitselfmid\-sessionanduseitrightaway\-wecoveredthedesignofthisina[previous blogpost](https://anoma.ly/notes/opencode-reloaded)\. YoucanaskOpenCodetobuildwhateverpluginyouwantanditknowshowto\.Butifyoudowanttoreadthedocs,theyareavailable[here](https://opencode.ai/v2/docs/build/plugins)\. ## The SDK OpenCodecanalsonowbeusedasalibrarywiththe`@opencode/sdk`package\.ThisistheexactsamecodethatpowersourCLI\. ThismeansyoucanstripitdownandmakeyourownflavorofOpenCodethatrunsonaserverorinspecializedenvironmentslikeDurableObjects\.AndthenyoucanconnecttoitfromanyOpenCodeclientsinceitspeaksthestandardOpenCodeserverprotocol\. ItalsohasanoptionalEffect\-basedAPI\. Thisoneisstillindevelopmentasthingsareshiftingbutyoucan[already use it](https://opencode.ai/v2/docs/build/sdk)\. ## Upgrading ToupgradetheCLI,makesureyou'reonthelatest1\.xrelease,thenrun`opencode``upgrade``\-\-major`\. Toupgradeyourdesktopapp,downloadthelatest[here](https://opencode.ai/download)\. Therearesomebreakingchanges\. 1\.0pluginswillnotworkin2\.0 ServerAPIiscompletelydifferent tui\.jsonconfigismovedtojson Therearealotofotherchangesbuttheyarebackwardscompatible\.ItisworthpointingOpenCodeat[this doc](https://opencode.ai/v2/docs/migrate-v1/)soitcanmigratethingsforyou\.