FEAT: Add multi-language support (EN / ZH / ES / HI) (#2)

- New translations.py with UI string dicts and language directives for all 4 languages
- Language dropdown in UI header — switching resets the session in the chosen language
- Intake and research agents prepend a language directive to their system prompts so
Claude responds entirely in the selected language (Chinese, Spanish, Hindi, English)
- PatientProfile.lang field carries language through to the research agent
- All hardcoded English UI strings replaced with UI[lang] lookups

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -20,20 +20,22 @@ from clinical_trials_guru import (
     geocode_zip,
     search_trials_api,
 )
+from translations import LANGUAGE_DIRECTIVE, LANGUAGES, UI
 
 load_dotenv()
 
 
 def _intake_turn(
-    user_text: str, messages: list
+    user_text: str, messages: list, lang: str = "en"
 ) -> tuple[str, list, PatientProfile | None]:
     today = datetime.date.today().strftime("%B %d, %Y")
     messages = messages + [{"role": "user", "content": user_text}]
     client = anthropic.Anthropic()
+    system = f"Today's date is {today}.\n\n" + LANGUAGE_DIRECTIVE[lang] + INTAKE_SYSTEM
     response = client.messages.create(
         model=INTAKE_MODEL,
         max_tokens=1024,
-        system=f"Today's date is {today}.\n\n" + INTAKE_SYSTEM,
+        system=system,
         tools=[SUBMIT_PROFILE_TOOL],
         messages=messages,
     )
@@ -63,13 +65,15 @@ def _intake_turn(
             radius_miles=data.get("radius_miles", 100),
             phases=data.get("phases") or [],
             include_eap=data.get("include_eap", False),
+            lang=lang,
         )
-        return text or "Got it — searching for trials now…", messages, profile
+        return text or UI[lang]["got_it"], messages, profile
 
     return text, messages, None
 
 
 def _run_research(profile: PatientProfile) -> str:
+    lang = profile.lang
     client = anthropic.Anthropic()
     messages: list[anthropic.types.MessageParam] = [
         {
@@ -84,7 +88,7 @@ def _run_research(profile: PatientProfile) -> str:
         response = client.messages.create(
             model=RESEARCH_MODEL,
             max_tokens=8096,
-            system=RESEARCH_SYSTEM,
+            system=LANGUAGE_DIRECTIVE[lang] + RESEARCH_SYSTEM,
             tools=[SEARCH_TRIALS_TOOL],
             messages=messages,
         )
@@ -92,7 +96,7 @@ def _run_research(profile: PatientProfile) -> str:
         if response.stop_reason == "end_turn":
             return next(
                 (b.text for b in response.content if b.type == "text"),
-                "No analysis produced.",
+                UI[lang]["no_analysis"],
             )
         tool_results: list[anthropic.types.ToolResultBlockParam] = []
         for block in response.content:
@@ -112,7 +116,7 @@ def _run_research(profile: PatientProfile) -> str:
                 content = json.dumps(ranked)
                 is_error = False
             except Exception as exc:
-                content = f"API request failed: {exc}"
+                content = UI[lang]["api_error"].format(exc=exc)
                 is_error = True
             tool_results.append(
                 {
@@ -125,11 +129,9 @@ def _run_research(profile: PatientProfile) -> str:
         messages.append({"role": "user", "content": tool_results})
 
 
-def initialize():
-    text, msgs, _ = _intake_turn("Please begin.", [])
+def initialize(lang: str = "en"):
+    text, msgs, _ = _intake_turn("Please begin.", [], lang=lang)
     chat = [{"role": "assistant", "content": text}]
-    # Strip the seed "Please begin." turn so subsequent user messages append cleanly.
-    # msgs already includes both the seed user turn and the assistant turn; keep it.
     return chat, msgs, None, "intake"
 
 
@@ -139,27 +141,27 @@ def respond(
     intake_msgs: list,
     profile,
     phase: str,
+    lang: str,
 ) -> Generator:
     if not user_msg.strip() or phase == "done":
         yield chat_history, intake_msgs, profile, phase, gr.update(), gr.update()
         return
 
+    t = UI[lang]
     chat_history = chat_history + [{"role": "user", "content": user_msg}]
     yield chat_history, intake_msgs, profile, phase, gr.update(value=""), gr.update()
 
-    assistant_text, updated_msgs, new_profile = _intake_turn(user_msg, intake_msgs)
+    assistant_text, updated_msgs, new_profile = _intake_turn(user_msg, intake_msgs, lang=lang)
 
     if new_profile:
-        status = (assistant_text + "\n\n" if assistant_text else "") + (
-            "*Searching ClinicalTrials.gov — this may take a minute…*"
-        )
+        status = (assistant_text + "\n\n" if assistant_text else "") + t["status_searching"]
         chat_history = chat_history + [{"role": "assistant", "content": status}]
         yield (
             chat_history,
             updated_msgs,
             new_profile,
             "researching",
-            gr.update(interactive=False, placeholder="Searching…"),
+            gr.update(interactive=False, placeholder=t["searching"]),
             gr.update(visible=False),
         )
 
@@ -170,7 +172,7 @@ def respond(
             updated_msgs,
             new_profile,
             "done",
-            gr.update(interactive=False, placeholder="Search complete."),
+            gr.update(interactive=False, placeholder=t["search_complete"]),
             gr.update(visible=True),
         )
     else:
@@ -185,43 +187,84 @@ def respond(
         )
 
 
-with gr.Blocks(title="Beacon — Clinical Trial Finder") as demo:
-    gr.Markdown("# 🔦 Beacon — Rare Disease Clinical Trial Finder")
+def change_language(lang: str):
+    t = UI[lang]
+    chat, msgs, _, phase = initialize(lang)
+    return (
+        chat, msgs, None, phase,
+        gr.update(value=t["heading"]),
+        gr.update(placeholder=t["placeholder"], interactive=True),
+        gr.update(value=t["send"]),
+        gr.update(value=t["new_search"], visible=False),
+        lang,
+    )
+
+
+with gr.Blocks(title=UI["en"]["page_title"]) as demo:
+    heading_md = gr.Markdown(UI["en"]["heading"])
+
+    with gr.Row():
+        gr.Markdown("")  # spacer
+        lang_dropdown = gr.Dropdown(
+            choices=[(label, code) for code, label in LANGUAGES.items()],
+            value="en",
+            show_label=False,
+            scale=1,
+            min_width=140,
+            container=False,
+        )
 
     chatbot = gr.Chatbot(height=550, show_label=False)
     with gr.Row():
         msg_box = gr.Textbox(
-            placeholder="Type your message and press Enter…",
+            placeholder=UI["en"]["placeholder"],
             show_label=False,
             scale=9,
             autofocus=True,
         )
-        send_btn = gr.Button("Send", scale=1, variant="primary")
-    new_search_btn = gr.Button("New Search", visible=False, variant="secondary")
+        send_btn = gr.Button(UI["en"]["send"], scale=1, variant="primary")
+    new_search_btn = gr.Button(UI["en"]["new_search"], visible=False, variant="secondary")
 
     # State
     intake_msgs_state = gr.State([])
     profile_state = gr.State(None)
     phase_state = gr.State("intake")
+    lang_state = gr.State("en")
 
-    outputs = [chatbot, intake_msgs_state, profile_state, phase_state, msg_box, new_search_btn]
+    respond_inputs = [msg_box, chatbot, intake_msgs_state, profile_state, phase_state, lang_state]
+    respond_outputs = [chatbot, intake_msgs_state, profile_state, phase_state, msg_box, new_search_btn]
 
     demo.load(
-        initialize,
+        lambda: initialize("en"),
         outputs=[chatbot, intake_msgs_state, profile_state, phase_state],
     )
 
-    msg_box.submit(respond, [msg_box, chatbot, intake_msgs_state, profile_state, phase_state], outputs)
-    send_btn.click(respond, [msg_box, chatbot, intake_msgs_state, profile_state, phase_state], outputs)
+    msg_box.submit(respond, respond_inputs, respond_outputs)
+    send_btn.click(respond, respond_inputs, respond_outputs)
 
     new_search_btn.click(
         initialize,
+        inputs=[lang_state],
         outputs=[chatbot, intake_msgs_state, profile_state, phase_state],
     ).then(
-        lambda: (gr.update(interactive=True, placeholder="Type your message and press Enter…"), gr.update(visible=False)),
+        lambda lang: (
+            gr.update(interactive=True, placeholder=UI[lang]["placeholder"]),
+            gr.update(visible=False),
+        ),
+        inputs=[lang_state],
         outputs=[msg_box, new_search_btn],
     )
 
+    lang_dropdown.change(
+        change_language,
+        inputs=[lang_dropdown],
+        outputs=[
+            chatbot, intake_msgs_state, profile_state, phase_state,
+            heading_md, msg_box, send_btn, new_search_btn,
+            lang_state,
+        ],
+    )
+
 
 if __name__ == "__main__":
     demo.launch()

clinical_trials_guru.py

@@ -6,6 +6,8 @@ import time
 from dataclasses import dataclass, field
 from typing import Optional, TypedDict
 
+from translations import LANGUAGE_DIRECTIVE
+
 import anthropic
 import httpx
 from rich import box
@@ -231,6 +233,7 @@ class PatientProfile:
     radius_miles: int = 100
     phases: list[str] = field(default_factory=list)
     include_eap: bool = False
+    lang: str = "en"
 
     def summary(self) -> str:
         lines = [

translations.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+LANGUAGES: dict[str, str] = {
+    "en": "English",
+    "zh": "中文",
+    "es": "Español",
+    "hi": "हिन्दी",
+}
+
+UI: dict[str, dict[str, str]] = {
+    "en": {
+        "page_title":        "Beacon — Clinical Trial Finder",
+        "heading":           "# 🔦 Beacon — Rare Disease Clinical Trial Finder",
+        "placeholder":       "Type your message and press Enter…",
+        "send":              "Send",
+        "new_search":        "New Search",
+        "searching":         "Searching…",
+        "search_complete":   "Search complete.",
+        "status_searching":  "*Searching ClinicalTrials.gov — this may take a minute…*",
+        "no_analysis":       "No analysis produced.",
+        "api_error":         "API request failed: {exc}",
+        "got_it":            "Got it — searching for trials now…",
+    },
+    "zh": {
+        "page_title":        "Beacon — 临床试验查找器",
+        "heading":           "# 🔦 Beacon — 罕见病临床试验查找器",
+        "placeholder":       "输入消息并按回车…",
+        "send":              "发送",
+        "new_search":        "新搜索",
+        "searching":         "搜索中…",
+        "search_complete":   "搜索完成。",
+        "status_searching":  "*正在搜索 ClinicalTrials.gov，请稍候…*",
+        "no_analysis":       "未生成分析结果。",
+        "api_error":         "API 请求失败：{exc}",
+        "got_it":            "好的，正在为您搜索临床试验…",
+    },
+    "es": {
+        "page_title":        "Beacon — Buscador de Ensayos Clínicos",
+        "heading":           "# 🔦 Beacon — Buscador de Ensayos Clínicos para Enfermedades Raras",
+        "placeholder":       "Escribe tu mensaje y presiona Enter…",
+        "send":              "Enviar",
+        "new_search":        "Nueva Búsqueda",
+        "searching":         "Buscando…",
+        "search_complete":   "Búsqueda completada.",
+        "status_searching":  "*Buscando en ClinicalTrials.gov, esto puede tomar un minuto…*",
+        "no_analysis":       "No se produjo ningún análisis.",
+        "api_error":         "Solicitud de API fallida: {exc}",
+        "got_it":            "Entendido, buscando ensayos ahora…",
+    },
+    "hi": {
+        "page_title":        "Beacon — क्लिनिकल ट्रायल खोजक",
+        "heading":           "# 🔦 Beacon — दुर्लभ रोग क्लिनिकल ट्रायल खोजक",
+        "placeholder":       "अपना संदेश टाइप करें और Enter दबाएं…",
+        "send":              "भेजें",
+        "new_search":        "नई खोज",
+        "searching":         "खोज रहे हैं…",
+        "search_complete":   "खोज पूर्ण।",
+        "status_searching":  "*ClinicalTrials.gov पर खोज हो रही है, एक मिनट लग सकता है…*",
+        "no_analysis":       "कोई विश्लेषण नहीं बना।",
+        "api_error":         "API अनुरोध विफल: {exc}",
+        "got_it":            "समझ गया — अभी ट्रायल खोज रहे हैं…",
+    },
+}
+
+LANGUAGE_DIRECTIVE: dict[str, str] = {
+    "en": "",
+    "zh": (
+        "IMPORTANT: You must respond ONLY in Simplified Chinese (简体中文). "
+        "Every word you write to the patient must be in Chinese. "
+        "Standard medical abbreviations (ALSFRS-R, FVC, SOD1, etc.) may remain in their original form.\n\n"
+    ),
+    "es": (
+        "IMPORTANTE: Debes responder ÚNICAMENTE en español. "
+        "Cada palabra que escribas al paciente debe estar en español. "
+        "Las abreviaturas médicas estándar (ALSFRS-R, FVC, SOD1, etc.) pueden mantenerse en su forma original.\n\n"
+    ),
+    "hi": (
+        "महत्वपूर्ण: आपको केवल हिन्दी में उत्तर देना है। "
+        "रोगी को लिखी गई हर बात हिन्दी में होनी चाहिए। "
+        "मानक चिकित्सा संक्षेप (ALSFRS-R, FVC, SOD1, आदि) अपने मूल रूप में रह सकते हैं।\n\n"
+    ),
+}