Simplify explorer to pure API backend

Remove custom HTML/JS frontend — it lives on the website at
/explore. Keep only Gradio API endpoints: ask, upload, doc,
traces, replay.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app.py

@@ -1,7 +1,7 @@
-"""Document Explorer — upload documents, ask questions with cited answers.
+"""Document Explorer — API backend for exploring uploaded documents with an LLM.
 
-The LLM explores documents by writing Python code. No training, no vector DB.
-Built on a-simple-llm-harness.
+The frontend lives on the AppSimple website. This Space provides
+streaming question/answer, file upload, and trace endpoints.
 """
 
 from __future__ import annotations
@@ -73,9 +73,9 @@ def upload_trace(result: dict) -> None:
         print(f"WARNING: trace upload failed: {exc}")
 
 
-def save_uploaded_files(files: list[str]) -> Path:
+def save_uploaded_files(file_paths: list[str]) -> Path:
     workspace = Path(tempfile.mkdtemp(prefix="lh-workspace-"))
-    for file_path in files:
+    for file_path in file_paths:
         src = Path(file_path)
         (workspace / src.name).write_bytes(src.read_bytes())
     return workspace
@@ -128,7 +128,6 @@ def stream_question(
     scratch_path: str,
     session_cost: float,
     token: str,
-    files: list[str] | None = None,
 ) -> Generator[str, None, None]:
     """Streaming API — yields JSON event strings."""
     if ACCESS_TOKEN and token != ACCESS_TOKEN:
@@ -147,9 +146,6 @@ def stream_question(
         return
 
     workspace = Path(workspace_path) if workspace_path else None
-    if files and not workspace:
-        workspace = save_uploaded_files(files)
-
     if not workspace:
         yield json.dumps({"type": "error", "error": "No documents uploaded."})
         return
@@ -217,262 +213,24 @@ def stream_question(
 
 
 # ---------------------------------------------------------------------------
-# Gradio app
+# Gradio app (API endpoints only)
 # ---------------------------------------------------------------------------
 
-_STATIC_DIR = Path(__file__).parent / "static"
-_CHAT_UI_CSS = (_STATIC_DIR / "chat-ui.css").read_text() if (_STATIC_DIR / "chat-ui.css").exists() else ""
-_CHAT_UI_JS = (_STATIC_DIR / "chat-ui.js").read_text() if (_STATIC_DIR / "chat-ui.js").exists() else ""
-
-CUSTOM_HTML = """
-<div id="explorer-app">
-    <div id="setup-panel">
-        <div class="setup-field">
-            <label for="token-input">Access Token</label>
-            <input type="password" id="token-input" placeholder="Enter your access token" />
-        </div>
-        <div class="setup-field">
-            <label>Upload Documents</label>
-            <div id="drop-zone" class="drop-zone">
-                <p>Drag and drop files here, or <label for="file-input" class="file-label">browse</label></p>
-                <input type="file" id="file-input" multiple accept=".txt,.csv,.md,.json,.pdf" style="display:none" />
-                <div id="file-list"></div>
-            </div>
-        </div>
-        <button id="start-btn" disabled>Start exploring</button>
-    </div>
-
-    <div id="chat-panel" style="display:none">
-        <div class="chat-container">
-            <div class="chat-history" id="chat-history"></div>
-            <div class="chat-input-wrapper">
-                <input type="text" id="chat-input" class="chat-input" placeholder="Ask a question about your documents..." autocomplete="off" />
-            </div>
-            <div class="chat-stats" id="session-cost"></div>
-        </div>
-    </div>
-</div>
-"""
-
-CUSTOM_CSS = _CHAT_UI_CSS + """
-#explorer-app { font-family: var(--font-family, 'Inter', system-ui, sans-serif); max-width: 800px; margin: 0 auto; }
-#setup-panel { padding: 24px 0; }
-.setup-field { margin-bottom: 16px; }
-.setup-field label { display: block; font-size: 13px; color: #6B7280; margin-bottom: 4px; }
-#token-input { width: 100%; padding: 8px 12px; border: 1px solid #E5E7EB; border-radius: 4px; font-family: inherit; font-size: 14px; }
-#token-input:focus { outline: none; border-color: #4682B4; }
-.drop-zone { border: 2px dashed #E5E7EB; border-radius: 8px; padding: 32px; text-align: center; color: #9CA3AF; cursor: pointer; transition: border-color 0.2s; }
-.drop-zone.drag-over { border-color: #4682B4; background: #f0f7ff; }
-.drop-zone p { margin: 0; }
-.file-label { color: #4682B4; cursor: pointer; text-decoration: underline; }
-#file-list { margin-top: 8px; font-size: 13px; color: #374151; text-align: left; }
-#file-list div { padding: 2px 0; }
-#start-btn { width: 100%; padding: 10px; background: #4682B4; color: white; border: none; border-radius: 4px; font-family: inherit; font-size: 14px; cursor: pointer; margin-top: 8px; }
-#start-btn:disabled { background: #D1D5DB; cursor: default; }
-#start-btn:not(:disabled):hover { background: #3a6f9a; }
-#chat-panel { padding-top: 8px; }
-"""
-
-CUSTOM_JS = _CHAT_UI_JS + """
-;document.addEventListener('DOMContentLoaded', function() {
-    var API_BASE = window.location.origin;
-    var tokenInput = document.getElementById('token-input');
-    var fileInput = document.getElementById('file-input');
-    var dropZone = document.getElementById('drop-zone');
-    var fileList = document.getElementById('file-list');
-    var startBtn = document.getElementById('start-btn');
-    var setupPanel = document.getElementById('setup-panel');
-    var chatPanel = document.getElementById('chat-panel');
-    var chatInput = document.getElementById('chat-input');
-    var chatHistory = document.getElementById('chat-history');
-    var sessionCostEl = document.getElementById('session-cost');
-
-    var selectedFiles = [];
-    var workspacePath = '';
-    var scratchPath = '';
-    var sessionCost = 0;
-
-    function updateStartBtn() {
-        startBtn.disabled = !(selectedFiles.length > 0);
-    }
-
-    function showFiles() {
-        fileList.innerHTML = selectedFiles.map(function(f) { return '<div>' + escapeHtml(f.name) + '</div>'; }).join('');
-        updateStartBtn();
-    }
-
-    fileInput.addEventListener('change', function() {
-        selectedFiles = Array.from(fileInput.files);
-        showFiles();
-    });
-
-    dropZone.addEventListener('click', function() { fileInput.click(); });
-    dropZone.addEventListener('dragover', function(e) { e.preventDefault(); dropZone.classList.add('drag-over'); });
-    dropZone.addEventListener('dragleave', function() { dropZone.classList.remove('drag-over'); });
-    dropZone.addEventListener('drop', function(e) {
-        e.preventDefault();
-        dropZone.classList.remove('drag-over');
-        selectedFiles = Array.from(e.dataTransfer.files);
-        showFiles();
-    });
-
-    startBtn.addEventListener('click', function() {
-        startBtn.disabled = true;
-        startBtn.textContent = 'Uploading...';
-
-        var formData = new FormData();
-        selectedFiles.forEach(function(f) { formData.append('files', f); });
-
-        fetch(API_BASE + '/gradio_api/upload', {
-            method: 'POST',
-            body: formData
-        })
-        .then(function(r) { return r.json(); })
-        .then(function(uploadedPaths) {
-            return fetch(API_BASE + '/gradio_api/call/upload', {
-                method: 'POST',
-                headers: { 'Content-Type': 'application/json' },
-                body: JSON.stringify({ data: [tokenInput.value, uploadedPaths] })
-            });
-        })
-        .then(function(r) { return r.json(); })
-        .then(function(result) {
-            return fetch(API_BASE + '/gradio_api/call/upload/' + result.event_id);
-        })
-        .then(function(r) { return r.text(); })
-        .then(function(text) {
-            var lines = text.split('\\n');
-            var dataLine = lines.find(function(l) { return l.startsWith('data:'); });
-            var parsed = JSON.parse(dataLine.substring(5).trim());
-            var data = JSON.parse(Array.isArray(parsed) ? parsed[0] : parsed);
-            if (data.error) {
-                startBtn.disabled = false;
-                startBtn.textContent = 'Start exploring';
-                alert(data.error);
-                return;
-            }
-            workspacePath = data.workspace_path;
-            setupPanel.style.display = 'none';
-            chatPanel.style.display = 'block';
-            chatInput.focus();
-        })
-        .catch(function(err) {
-            console.error(err);
-            startBtn.disabled = false;
-            startBtn.textContent = 'Start exploring';
-        });
-    });
-
-    chatInput.addEventListener('keydown', function(e) {
-        if (e.key !== 'Enter' || !chatInput.value.trim() || chatInput.disabled) return;
-        e.preventDefault();
-        var question = chatInput.value.trim();
-        chatInput.value = '';
-        chatInput.disabled = true;
-        chatInput.placeholder = '';
-
-        var turn = document.createElement('div');
-        turn.className = 'chat-turn';
-        turn.innerHTML = '<div class="chat-question">' + escapeHtml(question) + '</div>';
-        chatHistory.appendChild(turn);
-
-        var answerEl = document.createElement('div');
-        answerEl.className = 'chat-answer';
-        turn.appendChild(answerEl);
-        var accumulated = '';
-        var toolCount = 0;
-
-        fetch(API_BASE + '/gradio_api/call/ask', {
-            method: 'POST',
-            headers: { 'Content-Type': 'application/json' },
-            body: JSON.stringify({ data: [question, workspacePath, scratchPath, sessionCost, tokenInput.value] })
-        })
-        .then(function(r) { return r.json(); })
-        .then(function(result) {
-            var eventSource = new EventSource(API_BASE + '/gradio_api/call/ask/' + result.event_id);
-
-            function handleEvent(e) {
-                var raw = JSON.parse(e.data);
-                var eventData = JSON.parse(Array.isArray(raw) ? raw[0] : raw);
-
-                if (eventData.type === 'delta') {
-                    accumulated += eventData.content;
-                    answerEl.innerHTML = markdownToHtml(accumulated);
-                    answerEl.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
-                } else if (eventData.type === 'tool_call') {
-                    toolCount = eventData.count;
-                    answerEl.innerHTML = '<em class="chat-tool-status">Exploring documents (' + toolCount + ' tool calls)...</em>';
-                    accumulated = '';
-                } else if (eventData.type === 'error') {
-                    eventSource.close();
-                    answerEl.innerHTML = '<span class="chat-error">' + escapeHtml(eventData.error) + '</span>';
-                    chatInput.disabled = false;
-                    chatInput.placeholder = 'Ask a question about your documents...';
-                } else if (eventData.type === 'done') {
-                    eventSource.close();
-                    var finalHtml = '<div class="chat-answer">' + markdownToHtml(eventData.answer || accumulated) + '</div>';
-                    finalHtml += renderSources(eventData.sources);
-                    if (eventData.stats) {
-                        finalHtml += '<div class="chat-stats">' + eventData.stats + '</div>';
-                    }
-                    if (eventData.trace_html) {
-                        finalHtml += '<button class="chat-trace-toggle" onclick="this.nextElementSibling.classList.toggle(\\'open\\')">trace</button>';
-                        finalHtml += '<div class="chat-trace">' + eventData.trace_html + '</div>';
-                    }
-                    turn.innerHTML = '<div class="chat-question">' + escapeHtml(question) + '</div>' + finalHtml;
-
-                    if (eventData.workspace_path) workspacePath = eventData.workspace_path;
-                    if (eventData.scratch_path) scratchPath = eventData.scratch_path;
-                    if (eventData.session_cost != null) {
-                        sessionCost = eventData.session_cost;
-                        sessionCostEl.textContent = 'Session cost: $' + sessionCost.toFixed(4);
-                    }
-
-                    chatInput.disabled = false;
-                    chatInput.placeholder = 'Ask a question about your documents...';
-                    chatInput.focus({ preventScroll: true });
-                }
-            }
-
-            eventSource.addEventListener('generating', handleEvent);
-            eventSource.addEventListener('complete', handleEvent);
-
-            eventSource.onerror = function() {
-                eventSource.close();
-                if (!accumulated) {
-                    answerEl.innerHTML = '<span class="chat-error">Connection error.</span>';
-                }
-                chatInput.disabled = false;
-                chatInput.placeholder = 'Ask a question about your documents...';
-            };
-        })
-        .catch(function() {
-            turn.innerHTML += '<div class="chat-error">Connection error.</div>';
-            chatInput.disabled = false;
-            chatInput.placeholder = 'Ask a question about your documents...';
-        });
-    });
-});
-"""
-
 
 def build_app() -> gr.Blocks:
-    custom_head = f"<script>{CUSTOM_JS}</script>"
-    with gr.Blocks(title="Document Explorer", css=CUSTOM_CSS, head=custom_head) as demo:
-        gr.HTML(CUSTOM_HTML)
-
-        # Hidden state for file upload workspace
-        upload_workspace = gr.State("")
+    with gr.Blocks(title="Document Explorer") as demo:
+        gr.Markdown("# Document Explorer API\n\nThis Space provides the API backend. "
+                     "Visit [appsimple.io/explore](https://appsimple.io/explore) for the full interface.")
 
         # Streaming ask endpoint
-        api_ask_input = [
+        ask_inputs = [
             gr.Textbox(visible=False),  # question
             gr.Textbox(visible=False),  # workspace_path
             gr.Textbox(visible=False),  # scratch_path
             gr.Number(visible=False),   # session_cost
             gr.Textbox(visible=False),  # token
         ]
-        api_ask_output = gr.Textbox(visible=False)
+        ask_output = gr.Textbox(visible=False)
 
         def api_ask_stream(question, workspace_path, scratch_path, session_cost, token):
             for event_json in stream_question(
@@ -480,17 +238,12 @@ def build_app() -> gr.Blocks:
             ):
                 yield event_json
 
-        api_ask_btn = gr.Button(visible=False)
-        api_ask_btn.click(
-            api_ask_stream,
-            inputs=api_ask_input,
-            outputs=api_ask_output,
-            api_name="ask",
-        )
+        ask_btn = gr.Button(visible=False)
+        ask_btn.click(api_ask_stream, inputs=ask_inputs, outputs=ask_output, api_name="ask")
 
-        # Upload endpoint — accepts file paths from Gradio's /upload, creates workspace
-        upload_token_input = gr.Textbox(visible=False)
-        upload_files_input = gr.File(visible=False, file_count="multiple")
+        # Upload endpoint — accepts files, creates workspace
+        upload_token = gr.Textbox(visible=False)
+        upload_files = gr.File(visible=False, file_count="multiple")
         upload_output = gr.Textbox(visible=False)
 
         def api_upload(token, files):
@@ -498,22 +251,31 @@ def build_app() -> gr.Blocks:
                 return json.dumps({"error": "Invalid access token."})
             if not files:
                 return json.dumps({"error": "No files provided."})
-            file_paths = [f.name if hasattr(f, 'name') else str(f) for f in files]
+            file_paths = [f.name if hasattr(f, "name") else str(f) for f in files]
             workspace = save_uploaded_files(file_paths)
             return json.dumps({"workspace_path": str(workspace), "file_count": len(file_paths)})
 
         upload_btn = gr.Button(visible=False)
-        upload_btn.click(api_upload, inputs=[upload_token_input, upload_files_input], outputs=upload_output, api_name="upload")
+        upload_btn.click(api_upload, inputs=[upload_token, upload_files], outputs=upload_output, api_name="upload")
 
         # Document viewer endpoint
         doc_input = gr.Textbox(visible=False)
+        doc_ws_input = gr.Textbox(visible=False)
         doc_output = gr.Textbox(visible=False)
 
-        def api_get_doc(filename):
-            return json.dumps({"error": "not available"})
+        def api_get_doc(filename, workspace_path):
+            if not workspace_path or not filename:
+                return json.dumps({"error": "not found"})
+            safe_name = Path(filename).name
+            if not safe_name.endswith(".md"):
+                safe_name += ".md"
+            filepath = Path(workspace_path) / safe_name
+            if not filepath.is_file():
+                return json.dumps({"error": "not found"})
+            return json.dumps({"filename": safe_name, "content": filepath.read_text()})
 
         doc_btn = gr.Button(visible=False)
-        doc_btn.click(api_get_doc, inputs=doc_input, outputs=doc_output, api_name="doc")
+        doc_btn.click(api_get_doc, inputs=[doc_input, doc_ws_input], outputs=doc_output, api_name="doc")
 
         # Trace list endpoint
         traces_input = gr.Textbox(visible=False)