diff --git a/src/sw.js b/src/sw.js
new file mode 100644
index 0000000..9fb5bb1
--- /dev/null
+++ b/src/sw.js
@@ -0,0 +1,111 @@
+self.addEventListener("install",()=>{})
+self.addEventListener("activate",()=>{})
+
+const DB="sw-streams",STORE="sessions"
+let dbp=null
+function db(){if(dbp)return dbp;dbp=new Promise((res,rej)=>{const r=indexedDB.open(DB,1);r.onupgradeneeded=()=>{r.result.createObjectStore(STORE,{keyPath:"sid"})};r.onsuccess=()=>res(r.result);r.onerror=()=>rej(r.error)});return dbp}
+function idbGet(sid){return db().then(d=>new Promise((res,rej)=>{const t=d.transaction(STORE,"readonly").objectStore(STORE).get(sid);t.onsuccess=()=>res(t.result||null);t.onerror=()=>rej(t.error)}))}
+function idbPut(rec){return db().then(d=>new Promise((res,rej)=>{const t=d.transaction(STORE,"readwrite").objectStore(STORE).put(rec);t.onsuccess=()=>res();t.onerror=()=>rej(t.error)}))}
+function idbMerge(sid,patch){return idbGet(sid).then(cur=>{const rec=Object.assign({sid,text:"",done:false,updatedAt:Date.now()},cur||{},patch||{});rec.updatedAt=Date.now();return idbPut(rec)})}
+function idbAppend(sid,add){return idbGet(sid).then(cur=>{const rec=Object.assign({sid,text:"",done:false,updatedAt:Date.now()},cur||{});rec.text+=add;rec.updatedAt=Date.now();return idbPut(rec)})}
+function idbDelete(sid){return db().then(d=>new Promise((res,rej)=>{const t=d.transaction(STORE,"readwrite").objectStore(STORE).delete(sid);t.onsuccess=()=>res();t.onerror=()=>rej(t.error)}))}
+function idbAll(){return db().then(d=>new Promise((res,rej)=>{const t=d.transaction(STORE,"readonly").objectStore(STORE).getAll();t.onsuccess=()=>res(t.result||[]);t.onerror=()=>rej(t.error)}))}
+
+const ctrls=new Map()
+
+self.addEventListener("fetch",event=>{
+  const u=new URL(event.request.url)
+  const isOR=u.origin==="https://openrouter.ai"&&u.pathname==="/api/v1/chat/completions"&&event.request.method==="POST"
+  if(isOR){event.respondWith(proxyOpenRouter(event));return}
+  if(u.pathname==="/swproxy/history"&&event.request.method==="GET"){event.respondWith(handleHistory(u));return}
+  if(u.pathname==="/swproxy/clear"&&event.request.method==="POST"){event.respondWith(handleClear(event.request));return}
+  if(u.pathname==="/swproxy/abort"&&event.request.method==="POST"){event.respondWith(handleAbort(event.request));return}
+  if(u.pathname==="/swproxy/sessions"&&event.request.method==="GET"){event.respondWith(handleSessions());return}
+})
+
+async function proxyOpenRouter(event){
+  const req=event.request
+  let bodyText=""
+  try{bodyText=await req.clone().text()}catch(_){}
+  const isStream=/\"stream\"\s*:\s*true/.test(bodyText)
+  const sid="s_"+Math.random().toString(36).slice(2)+Date.now().toString(36)
+  await idbMerge(sid,{sid,text:"",done:false})
+  console.log("[SW] intercept",sid,"stream=",isStream)
+  const init={method:"POST",headers:new Headers(req.headers),body:bodyText||req.body,mode:"cors",cache:"no-store",credentials:"omit",signal:req.signal}
+  try{
+    const upstream=await fetch("https://openrouter.ai/api/v1/chat/completions",init)
+    const hs=new Headers(upstream.headers)
+    hs.set("Cache-Control","no-store")
+    hs.set("X-SW-Proxied","1")
+    hs.set("X-SW-Stream-Sid",sid)
+    if(!isStream||!upstream.body){await idbMerge(sid,{done:true});console.log("[SW]",sid,"non-stream or no body");return new Response(upstream.body,{status:upstream.status,statusText:upstream.statusText,headers:hs})}
+    const [branchClient,branchStore]=upstream.body.tee()
+    pumpToStore(branchStore,sid)
+    return new Response(branchClient,{status:upstream.status,statusText:upstream.statusText,headers:hs})
+  }catch(e){
+    await idbMerge(sid,{done:true})
+    console.log("[SW]",sid,"error",String(e&&e.message||e))
+    return new Response("upstream_error",{status:502})
+  }
+}
+
+function pumpToStore(stream,sid){
+  const reader=stream.getReader()
+  const dec=new TextDecoder()
+  let buf="",acc=0,last=0
+  function parsePush(txt){
+    buf+=txt
+    let i
+    while((i=buf.indexOf("\n\n"))!==-1){
+      const chunk=buf.slice(0,i).trim()
+      buf=buf.slice(i+2)
+      if(!chunk)continue
+      if(chunk.startsWith("data:")){
+        const data=chunk.slice(5).trim()
+        if(data==="[DONE]"){idbMerge(sid,{done:true});ctrls.delete(sid);console.log("[SW]",sid,"done totalChars=",acc);continue}
+        try{
+          const j=JSON.parse(data)
+          const d=j&&j.choices&&j.choices[0]&&j.choices[0].delta&&j.choices[0].delta.content||""
+          if(d){acc+=d.length;idbAppend(sid,d);if(acc-last>=500){last=acc;console.log("[SW]",sid,"bufferedChars=",acc)}}
+        }catch(_){}
+      }
+    }
+  }
+  function step(){return reader.read().then(({value,done})=>{
+    if(done){idbMerge(sid,{done:true});ctrls.delete(sid);console.log("[SW]",sid,"eof totalChars=",acc);return}
+    parsePush(dec.decode(value,{stream:true}))
+    return step()
+  }).catch(()=>{idbMerge(sid,{done:true});ctrls.delete(sid);console.log("[SW]",sid,"pump error")})}
+  step()
+}
+
+async function handleHistory(u){
+  const sid=u.searchParams.get("sid")||""
+  const rec=await idbGet(sid)
+  const body=JSON.stringify({sid,text:rec?.text||"",done:!!rec?.done,updatedAt:rec?.updatedAt||0})
+  return new Response(body,{status:200,headers:{"Content-Type":"application/json","Cache-Control":"no-store"}})
+}
+
+async function handleSessions(){
+  const all=await idbAll()
+  const list=all.map(x=>({sid:x.sid,textLen:(x.text||"").length,done:!!x.done,updatedAt:x.updatedAt||0}))
+  return new Response(JSON.stringify(list),{status:200,headers:{"Content-Type":"application/json","Cache-Control":"no-store"}})
+}
+
+async function handleClear(req){
+  const {sid}=await req.json()
+  await idbDelete(sid)
+  ctrls.delete(sid)
+  console.log("[SW]",sid,"cleared")
+  return new Response("ok",{status:200})
+}
+
+async function handleAbort(req){
+  const {sid}=await req.json()
+  const c=ctrls.get(sid)
+  if(c)c.abort()
+  ctrls.delete(sid)
+  await idbMerge(sid,{done:true})
+  console.log("[SW]",sid,"aborted")
+  return new Response("ok",{status:200})
+}