feat(web): mobile image upload to active session via paste dialog (#101)

- Extend the keyboard accessory paste dialog with an image picker
  (camera / photo library) plus best-effort image paste, routing
  selected files through the existing _uploadAndInsertImages pipeline
- Re-encode images to standard JPEG/PNG in the browser before upload,
  so mislabeled gallery images (e.g. MIUI WebP claiming image/jpeg)
  pass the server magic-byte check; PNG keeps transparency, GIF passes
  through untouched, decode failures fall back to the original file
- Log the real byte header on the paste-image magic-mismatch branch to
  pin down any remaining format mismatches without a guessing loop
- Ignore the runtime .claude-images/ upload directory

Co-authored-by: Teigen <teigen@TeigendeMac-mini.local>

.gitignore

@@ -66,3 +66,6 @@ commands
 todo.md
 @fix_plan.md
 readme-preview.mjs
+
+# Uploaded images land here under each session working dir (runtime artifact)
+.claude-images/

src/web/public/image-input.js

@@ -113,7 +113,14 @@ Object.assign(CodemanApp.prototype, {
     const paths = [];
     for (const file of files) {
       try {
-        const path = await this._uploadPasteImage(sessionId, file);
+        // Re-encode to a standard JPEG/PNG before upload. Galleries on some
+        // phones (notably Android/MIUI) hand back a WebP/HEIF whose filename and
+        // MIME claim "image/jpeg", which passes the server's extension allowlist
+        // but fails its magic-byte check ("bytes do not match declared type").
+        // Decoding through the browser and re-encoding guarantees the bytes
+        // match the extension we send.
+        const normalized = await this._normalizeImageForUpload(file);
+        const path = await this._uploadPasteImage(sessionId, normalized);
         paths.push(path);
       } catch (err) {
         this.showToast('Upload failed: ' + (err.message || 'unknown error'), 'error');
@@ -145,4 +152,49 @@ Object.assign(CodemanApp.prototype, {
     return data.path;
   },
 
+  // Decode an image File through the browser and re-encode it to a format the
+  // server accepts, so the uploaded bytes always match their declared
+  // extension. PNG is re-encoded as PNG (preserves transparency); everything
+  // else (JPEG, WebP, HEIF, unknown) becomes JPEG. Animated GIFs are passed
+  // through untouched since a canvas would flatten them to one frame. On any
+  // decode/encode failure the original file is returned unchanged so the server
+  // still gets a chance (and logs a precise diagnostic).
+  async _normalizeImageForUpload(file) {
+    if (file.type === 'image/gif') return file;
+
+    const toPng = file.type === 'image/png';
+    const url = URL.createObjectURL(file);
+    try {
+      const img = new Image();
+      await new Promise((resolve, reject) => {
+        img.onload = () => resolve();
+        img.onerror = () => reject(new Error('decode failed'));
+        img.src = url;
+      });
+
+      const width = img.naturalWidth;
+      const height = img.naturalHeight;
+      if (!width || !height) return file;
+
+      const canvas = document.createElement('canvas');
+      canvas.width = width;
+      canvas.height = height;
+      const ctx = canvas.getContext('2d');
+      if (!ctx) return file;
+      ctx.drawImage(img, 0, 0);
+
+      const mime = toPng ? 'image/png' : 'image/jpeg';
+      const blob = await new Promise((resolve) => canvas.toBlob(resolve, mime, 0.92));
+      if (!blob) return file;
+
+      const baseName = (file.name || 'image').replace(/\.[^.]+$/, '') || 'image';
+      return new File([blob], baseName + (toPng ? '.png' : '.jpg'), { type: mime });
+    } catch (err) {
+      console.warn('Image re-encode failed, uploading original:', err);
+      return file;
+    } finally {
+      URL.revokeObjectURL(url);
+    }
+  },
+
 });

src/web/public/keyboard-accessory.js

@@ -5,6 +5,8 @@
  *
  * - KeyboardAccessoryBar (singleton object) — Quick action buttons shown above the virtual
  *   keyboard on mobile: arrow up/down, /init, /clear, /compact, paste, and dismiss.
+ *   The paste button opens a dialog that handles both text paste and image attach
+ *   (native picker + best-effort image paste, routed through app._uploadAndInsertImages).
  *   Destructive actions (/clear, /compact) require double-tap confirmation (2s amber state).
  *   Commands are sent as text + Enter separately for Ink compatibility.
  *   Only initializes on touch devices (MobileDetection.isTouchDevice guard).
@@ -264,8 +266,17 @@ const KeyboardAccessoryBar = {
     }).catch(() => {});
   },
 
-  /** Read clipboard and send contents as input */
-  /** Show a paste overlay with a textarea for iOS compatibility */
+  /** Show a paste overlay for iOS compatibility.
+   *  Handles three input paths from one dialog:
+   *   - Text: long-press the textarea → Paste → Send (unchanged).
+   *   - Image (picker): the "Image" button opens a native file picker
+   *     (accept=image/* → camera / photo library / files), the most reliable
+   *     way to attach a photo on mobile.
+   *   - Image (paste): if the browser exposes image blobs on the textarea's
+   *     paste event, we intercept them and upload directly. Support is spotty
+   *     on mobile, so it is a best-effort enhancement layered on the picker.
+   *  All image paths reuse app._uploadAndInsertImages() (image-input.js), which
+   *  uploads to /api/sessions/:id/paste-image and inserts the saved path. */
   pasteFromClipboard() {
     if (typeof app === 'undefined' || !app.activeSessionId) return;
 
@@ -274,23 +285,61 @@ const KeyboardAccessoryBar = {
     overlay.className = 'paste-overlay';
     overlay.innerHTML = `
       <div class="paste-dialog">
-        <textarea class="paste-textarea" placeholder="Long-press here and tap Paste"></textarea>
+        <textarea class="paste-textarea" placeholder="Long-press to paste text — or tap 🖼 to attach an image"></textarea>
         <div class="paste-actions">
+          <button class="paste-image">🖼 Image</button>
           <button class="paste-cancel">Cancel</button>
           <button class="paste-send">Send</button>
         </div>
+        <input type="file" class="paste-file-input" accept="image/*" multiple hidden>
       </div>
     `;
 
     const textarea = overlay.querySelector('.paste-textarea');
-    const send = () => {
+    const fileInput = overlay.querySelector('.paste-file-input');
+
+    const close = () => overlay.remove();
+
+    const sendText = () => {
       const text = textarea.value;
-      overlay.remove();
+      close();
       if (text) app.sendInput(text);
     };
-    overlay.querySelector('.paste-cancel').addEventListener('click', () => overlay.remove());
-    overlay.querySelector('.paste-send').addEventListener('click', send);
-    overlay.addEventListener('click', (e) => { if (e.target === overlay) overlay.remove(); });
+
+    // Filter to images, close the dialog, and hand off to the shared
+    // upload+insert pipeline. Returns true if any image was handled.
+    const handleImages = (files) => {
+      const images = Array.from(files || []).filter((f) => f.type.startsWith('image/'));
+      if (images.length === 0) return false;
+      close();
+      if (typeof app._uploadAndInsertImages === 'function') app._uploadAndInsertImages(images);
+      return true;
+    };
+
+    // Image picker (camera / photo library) — the reliable mobile path.
+    overlay.querySelector('.paste-image').addEventListener('click', () => fileInput.click());
+    fileInput.addEventListener('change', () => handleImages(fileInput.files));
+
+    // Best-effort: capture images pasted straight into the textarea.
+    textarea.addEventListener('paste', (e) => {
+      const items = e.clipboardData && e.clipboardData.items;
+      if (!items) return;
+      const imageFiles = [];
+      for (let i = 0; i < items.length; i++) {
+        if (items[i].type.startsWith('image/')) {
+          const blob = items[i].getAsFile();
+          if (blob) imageFiles.push(blob);
+        }
+      }
+      if (imageFiles.length > 0) {
+        e.preventDefault();
+        handleImages(imageFiles);
+      }
+    });
+
+    overlay.querySelector('.paste-cancel').addEventListener('click', close);
+    overlay.querySelector('.paste-send').addEventListener('click', sendText);
+    overlay.addEventListener('click', (e) => { if (e.target === overlay) close(); });
 
     document.body.appendChild(overlay);
     textarea.focus();

src/web/public/mobile.css

@@ -1043,7 +1043,7 @@ html.mobile-init .file-browser-panel {
     margin-top: 10px;
   }
 
-  .paste-cancel, .paste-new, .paste-send {
+  .paste-cancel, .paste-new, .paste-send, .paste-image {
     padding: 8px 18px;
     border: none;
     border-radius: 8px;
@@ -1051,6 +1051,14 @@ html.mobile-init .file-browser-panel {
     cursor: pointer;
   }
 
+  /* Image attach button — left-aligned, accent outline */
+  .paste-image {
+    margin-right: auto;
+    background: var(--bg-tertiary, #333);
+    color: var(--accent-color, #7aa2f7);
+    border: 1px solid var(--accent-color, #7aa2f7);
+  }
+
   .paste-cancel {
     background: var(--bg-tertiary, #333);
     color: var(--text-secondary, #aaa);

src/web/routes/session-routes.ts

@@ -1674,6 +1674,14 @@ export function registerSessionRoutes(
     // Sniff actual bytes — filename and Content-Type are both attacker-supplied.
     // Polyglot HTML/PNG would otherwise pass and serve back with image/png MIME.
     if (!imageMagicMatchesExt(imageBytes, ext)) {
+      // Diagnostic: on some Android galleries (e.g. MIUI) a WebP/HEIF is
+      // mislabeled as image/jpeg, so the declared ext passes the allowlist but
+      // the magic bytes do not. Log the real header so format mismatches can be
+      // pinned down without a reproduce-and-guess loop. The client now
+      // re-encodes images to JPEG/PNG before upload, so this should be rare.
+      console.warn(
+        `[paste-image] magic mismatch: filename=${JSON.stringify(part.filename)} mime=${JSON.stringify(part.mimetype)} declaredExt=${ext} magic=${imageBytes.subarray(0, 12).toString('hex')}`
+      );
       reply.code(415);
       return createErrorResponse(ApiErrorCode.INVALID_INPUT, `Image bytes do not match declared type ${ext}`);
     }