got it to work :)

app.py

@@ -9,7 +9,7 @@ import time
 import shutil
 
 import pickle
-
+docs = None
 
 #title
 st.title("Encode knowledge from papers with cited references")
@@ -23,6 +23,7 @@ api_key = st.text_input('OpenAI API Key',
          type="password")
          
 # st.write('The current movie title is', title)
+api_key = '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'
 os.environ["OPENAI_API_KEY"] = f"{api_key}" # 
 import paperqa
 
@@ -129,12 +130,13 @@ def download_pdf(pdf_info):
 
 max_results_current = 1
 max_results = max_results_current
-pdf_info = ''
-pdf_citation = ''
+# pdf_info = ''
+# pdf_citation = ''
 def search_click_callback(search_query, max_results):
     global pdf_info, pdf_citation
     pdf_info, pdf_citation = call_arXiv_API(f'{search_query}', max_results=max_results)
     download_pdf(pdf_info)
+    return pdf_info
 
 
 
@@ -142,7 +144,7 @@ def search_click_callback(search_query, max_results):
 with st.form(key='columns_in_form', clear_on_submit = False):
     c1, c2 = st.columns([8,1])
     with c1:
-        search_query = st.text_input("Input search query here:", placeholder='Keywords for most relevant search...', value=''
+        search_query = st.text_input("Input search query here:", placeholder='Keywords for most relevant search...', value='CFD modeling'
                                        )#search_query, max_results_current))
 
     with c2:
@@ -152,22 +154,23 @@ with st.form(key='columns_in_form', clear_on_submit = False):
     #         search_click(search_query, max_results_default)
 
 if searchButton:
-    text = st.write(search_click_callback(search_query, max_results))
+    global pdf_info
+    pdf_info =  search_click_callback(search_query, max_results)
+    if 'pdf_info' not in st.session_state:
+        st.session_state['pdf_info'] = pdf_info
+    print(f'This is PDF info from search:{pdf_info}')
 
-def tokenize_callback():
-    global docs
-    docs = paperqa.Docs()
-    pdf_paths = [f"{p[4]}/{p[0]}.pdf" for p in pdf_info]
-    pdf_citations = [p[5] for p in pdf_info]
 
-    for d, c in stqdm(zip(pdf_paths, pdf_citations)):
-        docs.add(d, c)
+# def tokenize_callback():
+
     # return docs
 
-tokenization_form = st.form(key='tokenization-form')
-tokenization_form.markdown(f"Happy with your paper search results? ")
-toknizeButton = tokenization_form.form_submit_button(label = "Yes! Let's tokenize.", on_click=tokenize_callback())
-tokenization_form.markdown("If not, change keywords and search again. [This step costs!](https://openai.com/api/pricing/)")
+# tokenization_form = st.form(key='tokenization-form')
+# tokenization_form.markdown(f"Happy with your paper search results? ")
+# toknizeButton = tokenization_form.form_submit_button(label = "Yes! Let's tokenize.", on_click=tokenize_callback())
+# tokenization_form.markdown("If not, change keywords and search again. [This step costs!](https://openai.com/api/pricing/)")
+
+
 
 # submitButton = form.form_submit_button('Submit')
 # with st.form(key='tokenization_form', clear_on_submit = False):
@@ -179,18 +182,34 @@ tokenization_form.markdown("If not, change keywords and search again. [This step
 # if toknizeButton:
 #     tokenize_callback()
 
+# tokenize_callback()
+
 def answer_callback(question_query):
+    global docs
+    # global pdf_info
+    if docs is None:
+        pdf_info = st.session_state['pdf_info']
+        print('buliding docs')
+        docs = paperqa.Docs()
+        pdf_paths = [f"{p[4]}/{p[0]}.pdf" for p in pdf_info]
+        pdf_citations = [p[5] for p in pdf_info]
+        print(list(zip(pdf_paths, pdf_citations)))
+
+        for d, c in stqdm(zip(pdf_paths, pdf_citations)):
+            print(d,c)
+            docs.add(d, c)
+    # docs._build_faiss_index()
     answer = docs.query(question_query)
     print(answer.formatted_answer)
     return answer.formatted_answer
 
 form = st.form(key='question_form')
 question_query = form.text_input("What do you wanna know from these papers?", placeholder='Input questions here...',
-                value='')
+                value='Write 50 words on CFD modeling')
 submitButton = form.form_submit_button('Submit')
 
 if submitButton:
-    text = st.text_area("Answer:", answer_callback(question_query), height=300)
+    text = st.text_area("Answer:", answer_callback(question_query), height=600)
 
 # with st.form(key='question_form', clear_on_submit = False):
 #     question_query = st.text_input("What do you wanna know from these papers?", placeholder='Input questions here')