diff --git a/src/Flows.js b/src/Flows.js
index ce3deaef..2c5efeaa 100644
--- a/src/Flows.js
+++ b/src/Flows.js
@@ -48,7 +48,8 @@ function load_single_meta(show_sidebar,token) {
                 show_sidebar(
                     '帖子详情',
                     <div className="box box-tip">
-                        <a onClick={()=>load_single_meta(show_sidebar,token)}>重新加载</a>
+                        <p><a onClick={()=>load_single_meta(show_sidebar,token)()}>重新加载</a></p>
+                        <p>{''+e}</p>
                     </div>
                 );
             })
@@ -139,6 +140,7 @@ class FlowSidebar extends PureComponent {
             info: props.info,
             replies: props.replies,
             loading_status: 'done',
+            error_msg: null,
         };
         this.color_picker=props.color_picker;
         this.show_pid=load_single_meta(this.props.show_sidebar,this.props.token);
@@ -172,6 +174,7 @@ class FlowSidebar extends PureComponent {
     load_replies(update_count=true) {
         this.setState({
             loading_status: 'loading',
+            error_msg: null,
         });
         API.load_replies(this.state.info.pid,this.props.token,this.color_picker)
             .then((json)=>{
@@ -182,6 +185,7 @@ class FlowSidebar extends PureComponent {
                     }) : prev.info,
                     attention: !!json.attention,
                     loading_status: 'done',
+                    error_msg: null,
                 }), ()=>{
                     this.syncState({
                         replies: this.state.replies,
@@ -195,6 +199,7 @@ class FlowSidebar extends PureComponent {
                 this.setState({
                     replies: [],
                     loading_status: 'done',
+                    error_msg: ''+e,
                 });
             });
     }
@@ -240,8 +245,13 @@ class FlowSidebar extends PureComponent {
     show_reply_bar(name,event) {
         if(this.reply_ref.current && event.target.tagName.toLowerCase()!=='a') {
             let text=this.reply_ref.current.get();
-            if(/^\s*(Re (洞主|\b[A-Z][a-z]+){0,2}:)?\s*$/.test(text)) // text is nearly empty so we can replace it
-                this.reply_ref.current.set('Re '+name+': ');
+            if(/^\s*(Re (洞主|\b[A-Z][a-z]+){0,2}:)?\s*$/.test(text)) {// text is nearly empty so we can replace it
+                let should_text='Re '+name+': ';
+                if(should_text===this.reply_ref.current.get())
+                    this.reply_ref.current.set('');
+                else
+                    this.reply_ref.current.set(should_text);
+            }
         }
     }
 
@@ -278,7 +288,13 @@ class FlowSidebar extends PureComponent {
                         set_variant={(variant)=>{this.set_variant(null,variant);}}
                     />
                 </ClickHandler>
-                {(this.props.deletion_detect && parseInt(this.state.info.reply)>this.state.replies.length) &&
+                {!!this.state.error_msg &&
+                    <div className="box box-tip flow-item box-danger">
+                        <p>回复加载失败</p>
+                        <p>{this.state.error_msg}</p>
+                    </div>
+                }
+                {(this.props.deletion_detect && parseInt(this.state.info.reply)>this.state.replies.length) && !!this.state.replies.length &&
                     <div className="box box-tip flow-item box-danger">
                         {parseInt(this.state.info.reply)-this.state.replies.length} 条回复被删除
                     </div>
@@ -422,6 +438,7 @@ export class Flow extends PureComponent {
                 data: [],
             },
             loading_status: 'done',
+            error_msg: null,
         };
         this.on_scroll_bound=this.on_scroll.bind(this);
         window.LATEST_POST_ID=parseInt(localStorage['_LATEST_POST_ID'],10)||0;
@@ -433,6 +450,7 @@ export class Flow extends PureComponent {
             this.setState((prev,props)=>({
                 loaded_pages: prev.loaded_pages-1,
                 loading_status: 'failed',
+                error_msg: ''+err,
             }));
         };
 
@@ -508,6 +526,7 @@ export class Flow extends PureComponent {
             this.setState((prev,props)=>({
                 loaded_pages: prev.loaded_pages+1,
                 loading_status: 'loading',
+                error_msg: null,
             }));
         }
     }
@@ -540,7 +559,8 @@ export class Flow extends PureComponent {
                 />
                 {this.state.loading_status==='failed' &&
                     <div className="box box-tip aux-margin">
-                        <a onClick={()=>{this.load_page(this.state.loaded_pages+1)}}>重新加载</a>
+                        <p><a onClick={()=>{this.load_page(this.state.loaded_pages+1)}}>重新加载</a></p>
+                        <p>{this.state.error_msg}</p>
                     </div>
                 }
                 <TitleLine text={
diff --git a/src/UserAction.css b/src/UserAction.css
index d64f9f83..620c41b6 100644
--- a/src/UserAction.css
+++ b/src/UserAction.css
@@ -42,6 +42,11 @@
 .post-form-bar button {
     flex: 0 0 8em;
 }
+.post-form-img-tip {
+    font-size: small;
+    margin-top: -.5em;
+    margin-bottom: .5em;
+}
 .post-form textarea {
     resize: vertical;
     width: 100%;
diff --git a/src/UserAction.js b/src/UserAction.js
index 1237c25f..e7f9c990 100644
--- a/src/UserAction.js
+++ b/src/UserAction.js
@@ -7,8 +7,8 @@ import './UserAction.css';
 
 import {API_BASE} from './Common';
 const LOGIN_BASE=PKUHELPER_ROOT+'services/login';
-const MAX_IMG_PX=2000;
-const MAX_IMG_FILESIZE=256000;
+const MAX_IMG_PX=2500;
+const MAX_IMG_FILESIZE=300000;
 
 const ISOP_APPKEY='0feb3a8a831e11e8933a0050568508a5';
 const ISOP_APPCODE='0fec960a831e11e8933a0050568508a5';
@@ -265,10 +265,12 @@ export class PostForm extends Component {
         this.state={
             text: '',
             loading_status: 'done',
+            img_tip: null,
         };
         this.img_ref=React.createRef();
         this.area_ref=React.createRef();
         this.on_change_bound=this.on_change.bind(this);
+        this.on_img_change_bound=this.on_img_change.bind(this);
     }
 
     componentDidMount() {
@@ -327,7 +329,7 @@ export class PostForm extends Component {
                 if(idx===-1)
                     throw new Error('img not base64 encoded');
 
-                resolve(url.substr(idx+8));
+                return url.substr(idx+8);
             }
 
             let reader=new FileReader();
@@ -339,13 +341,16 @@ export class PostForm extends Component {
                 image.onload=(()=>{
                     let width=image.width;
                     let height=image.height;
+                    let compressed=false;
                     if(width>MAX_IMG_PX) {
                         height=height*MAX_IMG_PX/width;
                         width=MAX_IMG_PX;
+                        compressed=true;
                     }
                     if(height>MAX_IMG_PX) {
                         width=width*MAX_IMG_PX/height;
                         height=MAX_IMG_PX;
+                        compressed=true;
                     }
 
                     let canvas=document.createElement('canvas');
@@ -354,23 +359,58 @@ export class PostForm extends Component {
                     canvas.height=height;
                     ctx.drawImage(image,0,0,width,height);
 
-                    for(let quality=.9;quality>0;quality-=0.1) {
-                        const url=canvas.toDataURL('image/jpeg',quality);
-                        console.log('quality',quality,'size',url.length);
-                        if(url.length<=MAX_IMG_FILESIZE) {
-                            console.log('chosen img quality',quality);
-                            return return_url(url);
-                        }
+                    let quality_l=.1,quality_r=.9,quality,new_url;
+                    while(quality_r-quality_l>=.06) {
+                        quality=(quality_r+quality_l)/2;
+                        new_url=canvas.toDataURL('image/jpeg',quality);
+                        console.log(quality_l,quality_r,'trying quality',quality,'size',new_url.length);
+                        if(new_url.length<=MAX_IMG_FILESIZE)
+                            quality_l=quality;
+                        else
+                            quality_r=quality;
+                    }
+                    if(quality_l>=.101) {
+                        console.log('chosen img quality',quality);
+                        resolve({
+                            img: return_url(new_url),
+                            quality: quality,
+                            width: Math.round(width),
+                            height: Math.round(height),
+                            compressed: compressed,
+                        });
+                    } else {
+                        reject('图片过大，无法上传');
                     }
-                    // else
-                    alert('图片过大，无法上传');
-                    reject('img too large');
                 });
             });
             reader.readAsDataURL(file);
         });
     }
 
+    on_img_change() {
+        if(this.img_ref.current && this.img_ref.current.files.length)
+            this.setState({
+                img_tip: '（正在处理图片……）'
+            },()=>{
+                this.proc_img(this.img_ref.current.files[0])
+                    .then((d)=>{
+                        this.setState({
+                            img_tip: `（${d.compressed?'压缩到':'尺寸'} ${d.width}*${d.height} / `+
+                                `质量 ${Math.floor(d.quality*100)}% / ${Math.floor(d.img.length/1000)}KB）`,
+                        });
+                    })
+                    .catch((e)=>{
+                        this.setState({
+                            img_tip: `图片无效：${e}`,
+                        });
+                    });
+            });
+        else
+            this.setState({
+                img_tip: null,
+            });
+    }
+
     on_submit(event) {
         if(event) event.preventDefault();
         if(this.state.loading_status==='loading')
@@ -380,12 +420,15 @@ export class PostForm extends Component {
                 loading_status: 'processing',
             });
             this.proc_img(this.img_ref.current.files[0])
-                .then((img)=>{
+                .then((d)=>{
                     this.setState({
                         loading_status: 'loading',
                     });
-                    this.do_post(this.state.text,img);
+                    this.do_post(this.state.text,d.img);
                 })
+                .catch((e)=>{
+                    alert(e);
+                });
         } else {
             this.setState({
                 loading_status: 'loading',
@@ -400,8 +443,9 @@ export class PostForm extends Component {
                 <div className="post-form-bar">
                     <label>
                         图片
-                        <input ref={this.img_ref} type="file" accept="image/*"
-                            {...this.state.loading_status!=='done' ? {disabled: true} : {}} />
+                        <input ref={this.img_ref} type="file" accept="image/*" disabled={this.state.loading_status!=='done'}
+                               onChange={this.on_img_change_bound}
+                        />
                     </label>
                     {this.state.loading_status!=='done' ?
                         <button disabled="disabled">
@@ -414,6 +458,12 @@ export class PostForm extends Component {
                         </button>
                     }
                 </div>
+                {!!this.state.img_tip &&
+                    <p className="post-form-img-tip">
+                        <a onClick={()=>{this.img_ref.current.value=""; this.on_img_change();}}>删除图片</a>
+                        {this.state.img_tip}
+                    </p>
+                }
                 <SafeTextarea ref={this.area_ref} id="new_post" on_change={this.on_change_bound} on_submit={this.on_submit.bind(this)} />
             </form>
         )
diff --git a/src/flows_api.js b/src/flows_api.js
index 36465272..b1f801c7 100644
--- a/src/flows_api.js
+++ b/src/flows_api.js
@@ -17,8 +17,10 @@ export const API={
         )
             .then((res)=>res.json())
             .then((json)=>{
-                if(json.code!==0)
-                    throw new Error(json);
+                if(json.code!==0) {
+                    if(json.msg) throw new Error(json.msg);
+                    else throw new Error(json);
+                }
 
                 json.data=json.data
                     .sort((a,b)=>{
@@ -121,8 +123,8 @@ export const API={
             .then((res)=>res.json())
             .then((json)=>{
                 if(json.code!==0) {
-                    if(json.msg) alert(json.msg);
-                    throw new Error(json);
+                    if(json.msg) throw new Error(json.msg);
+                    else throw new Error(json);
                 }
                 return json;
             });
diff --git a/src/text_splitter.js b/src/text_splitter.js
index 4eb694d6..93e817a7 100644
--- a/src/text_splitter.js
+++ b/src/text_splitter.js
@@ -1,6 +1,6 @@
 export const PID_RE=/(^|[^\d])([1-9]\d{4,5})(?!\d|\u20e3)/g;
 export const NICKNAME_RE=/(^|[^A-Za-z])((?:(?:Angry|Baby|Crazy|Diligent|Excited|Fat|Greedy|Hungry|Interesting|Japanese|Kind|Little|Magic|Naïve|Old|Powerful|Quiet|Rich|Superman|THU|Undefined|Valuable|Wifeless|Xiangbuchulai|Young|Zombie)\s)?(?:Alice|Bob|Carol|Dave|Eve|Francis|Grace|Hans|Isabella|Jason|Kate|Louis|Margaret|Nathan|Olivia|Paul|Queen|Richard|Susan|Thomas|Uma|Vivian|Winnie|Xander|Yasmine|Zach)|You Win(?: \d+)?|洞主)(?![A-Za-z])/gi;
-export const URL_RE=/(?:^|\b)((?:https?:\/\/)?(?:[\w-]+\.)+[a-zA-Z]{2,3}(?::\d{1,5})?(?:\/[\w~!@#$%^&*()-_=+[\];,./?]*)?)(?:$|\b)/gi;
+export const URL_RE=/(?:^|\b)((?:https?:\/\/)?(?:[\w-]+\.)+[a-zA-Z]{2,3}(?::\d{1,5})?(?:\/[\w~!@#$%^&*()-_=+[\];,./?]*)?)/gi;
 
 export function split_text(txt,rules) {
     // rules: [['name',/regex/],...]