{"_id": {"$oid": "6a26c67c3572c06bc1455ecf"}, "test_id": "T1129", "benchmark": "business_letters", "date": "2026-06-05", "tags": {"document-type": ["letter"], "writing": ["typed", "handwritten"], "century": [20], "language": ["de"], "layout": ["prose"], "entry-type": ["person", "location"], "task": ["information-extraction"]}, "contributors": ["eric_decker", "maximilian_hindermann", "lea_kasper", "anthea_alberto", "pema_frick", "jose_luis_losada_palenzuela", "sorin_marti", "elena_spadini"], "hidden": false, "config": {"provider": "openrouter", "model": "stepfun/step-3.7-flash", "dataclass": "Document", "temperature": 0.0, "role_description": "You are a historian with keyword knowledge and an expert in the field of 20th century Swiss history", "prompt_file": "prompt.txt", "legacy_test": false}, "prompt": "            IDENTITY and PURPOSE:\n\n            You are presented with a series of images constituting a historical letter. Your task is to extract the\n            values of the following keys from the letter and return them in a JSON file where the values\n            corresponding to each key should be stored as a list, even if there is only a single value for a\n            key:\n\n            - letter_title: Title of the letter.\n            - sender_persons: Name(s) of the person(s) who wrote the letter.\n            - send_date: The exact or approximate date the letter was written.\n            - receiver_persons: Name(s) of the person(s) who received the letter.\n\n            Take a deep breath and think step by step about how to best accomplish this goal. Map out all the claims\n            and implications on a virtual whiteboard in your mind. Do not use OCR. Use the ISO format YYYY-MM-DD for\n            dates. If a piece of information is not included in the letter, set the value for the corresponding key\n            to \"null\". Do not return anything except the JSON file.\n\n            EXAMPLE:\n\n            {\n                \"letter_title\": [\"Petition for Environmental Protection\"],\n                \"send_date\": [\"1993-03-12\"],\n                \"sender_persons\": [\"Lisa Simpson\"],\n                \"receiver_persons\": [\"Mayor Joe Quimby\", \"Seymour Skinner\"],\n            }\n\n            OUTPUT:", "results": {"text": "{\"metadata\":{\"send_date\":[\"1928-04-02\"],\"letter_title\":[\"\"],\"sender_persons\":[\"Basler Rheinschiffahrt-Aktiengesellschaft\"],\"receiver_persons\":[\"Basler Personenschiffahrtsgesellschaft\"]}}", "model": "stepfun/step-3.7-flash-20260528", "provider": "openrouter", "finish_reason": "stop", "usage": {"input_tokens": 5013, "output_tokens": 3694, "total_tokens": 8707, "input_cost_usd": 0.0010026, "output_cost_usd": 0.0042480999999999994, "estimated_cost_usd": 0.0052507}, "duration": 659.1176948547363, "timestamp": "2026-06-05T13:10:21.942593", "parsed": {"metadata": {"send_date": ["1928-04-02"], "letter_title": [""], "sender_persons": ["Basler Rheinschiffahrt-Aktiengesellschaft"], "receiver_persons": ["Basler Personenschiffahrtsgesellschaft"], "document_number": "letter22"}}, "conversation_id": "d1df9455-9bf7-4891-9cab-def37247bd95", "score": {"send_date_tp": 1, "send_date_fp": 0, "send_date_fn": 0, "sender_persons_tp": 0, "sender_persons_fp": 1, "sender_persons_fn": 2, "receiver_persons_tp": 0, "receiver_persons_fp": 1, "receiver_persons_fn": 0}, "raw_response": "{\"id\":\"gen-1780657774-zXcdnsgQ27n988J5yz2z\",\"choices\":[{\"finish_reason\":\"stop\",\"index\":0,\"logprobs\":null,\"message\":{\"content\":\"{\\n        \\\"metadata\\\": {\\n            \\\"send_date\\\": [\\\"1928-04-02\\\"],\\n            \\\"letter_title\\\": [\\\"\\\"],\\n            \\\"sender_persons\\\": [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"],\\n            \\\"receiver_persons\\\": [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n        }\\n    }\",\"refusal\":null,\"role\":\"assistant\",\"annotations\":null,\"audio\":null,\"function_call\":null,\"tool_calls\":null,\"parsed\":{\"metadata\":{\"send_date\":[\"1928-04-02\"],\"letter_title\":[\"\"],\"sender_persons\":[\"Basler Rheinschiffahrt-Aktiengesellschaft\"],\"receiver_persons\":[\"Basler Personenschiffahrtsgesellschaft\"]}},\"reasoning\":\"The user wants me to extract specific information from a historical letter and return it in JSON format. The letter is in German and appears to be from 1928.\\n\\n Let me analyze the images:\\n\\n 1. First image (cover letter):\\n    - Date: Basel, den 2. April 1928\\n    - Sender: Basler Rheinschiffahrt-Aktiengesellschaft (Basel Rhine Shipping Company)\\n    - Receiver: Basler Personenschiffahrtsgesellschaft, Basel\\n    - Content: Sending a copy of a letter to Kur- und Verkehrsverein Rheinfelden regarding shipping between Basel and Rheinfelden\\n    - Signature: There's a signature, but it's not clearly legible as a specific person's name. It looks like \\\"Grundig\\\" or similar, but the letterhead shows the company name.\\n\\n 2. Second image (first page of the letter):\\n    - Date: Basel, den 2. April 1928\\n    - To: BASLER PERSONENSCHIFFFAHRTSGESELLSCHAFT\\n    - From: Kur- und Verkehrsverein, Rheinfelden\\n    - Subject: Betrifft Schiffahrt Basel-Rheinfelden (Concerning shipping Basel-Rheinfelden)\\n    - This appears to be the letter being referenced in the cover letter.\\n\\n 3. Third image (continuation):\\n    - Date: Rheinfelden, 2.4.28\\n    - Continuation of the letter from Kur- und Verkehrsverein to Basler Personenschiffahrtsgesellschaft\\n\\n Wait, I need to be careful here. The first image is a cover letter from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft, enclosing a copy of a letter.\\n\\n The second and third images appear to be the actual letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft, dated April 2, 1928.\\n\\n But the task asks for the letter title, sender, date, and receiver. Which letter? The cover letter or the enclosed letter?\\n\\n Looking at the first image, it's a cover letter from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n The second image shows the letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft.\\n\\n Actually, looking more carefully:\\n - Image 1: Cover letter from Basler Rheinschiffahrt-Aktiengesellschaft (sender) to Basler Personenschiffahrtsgesellschaft (receiver), dated 2. April 1928.\\n - Image 2: The enclosed letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft, also dated 2. April 1928.\\n - Image 3: Continuation of the enclosed letter.\\n\\n The task says \\\"You are presented with a series of images constituting a historical letter.\\\" This suggests all images together constitute one letter/document.\\n\\n The cover letter (Image 1) is from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n The enclosed letter (Images 2-3) is from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft.\\n\\n But the cover letter is the outer letter. The task likely refers to the cover letter as the main letter, or possibly the entire correspondence.\\n\\n Let me look at the keys:\\n - letter_title: Title of the letter.\\n - sender_persons: Name(s) of the person(s) who wrote the letter.\\n - send_date: The exact or approximate date the letter was written.\\n - receiver_persons: Name(s) of the person(s) who received the letter.\\n\\n For the cover letter (Image 1):\\n - Sender: Basler Rheinschiffahrt-Aktiengesellschaft (this is a company, not a person, but the task asks for \\\"person(s)\\\")\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: There's no explicit title, but the content mentions sending a copy of a letter. The subject is about shipping between Basel and Rheinfelden.\\n\\n For the enclosed letter (Images 2-3):\\n - Sender: Kur- und Verkehrsverein Rheinfelden (also an organization)\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Subject: Betrifft Schiffahrt Basel-Rheinfelden\\n\\n Since the first image is the cover letter and the others are enclosures, and the task mentions \\\"a historical letter\\\" (singular), I should probably focus on the cover letter, or treat the whole thing as one document.\\n\\n However, looking at the signature on the first image, it appears to be signed by an individual, though the name is hard to read. It looks like it could be \\\"Grundig\\\" or similar.\\n\\n Actually, looking at the letterhead on the first image:\\n - Basler Rheinschiffahrt-Aktiengesellschaft\\n - Marktgasse 5\\n - Various contact details\\n\\n The signature appears to be \\\"Grundig\\\" or \\\"Grund\\\" with a flourish.\\n\\n But the task asks for \\\"sender_persons\\\" - if it's a company, should I list the company name or the individual? The example shows \\\"Lisa Simpson\\\" as a person. But in historical documents, often the company name is used.\\n\\n Let me reconsider. The first image is clearly a cover letter. The text says: \\\"In der Beilage senden wir Ihnen Kopie unseres heutigen Schreibens an den Kur- und Verkehrsverein Rheinfelden zur gefl. Kenntnisnahme.\\\"\\n\\n So the sender is Basler Rheinschiffahrt-Aktiengesellschaft.\\n The receiver is Basler Personenschiffahrtsgesellschaft.\\n The date is 2. April 1928.\\n\\n For the title, there isn't really a title, but the subject matter is about the shipping route Basel-Rheinfelden.\\n\\n Wait, looking at the second image, the letter from Kur- und Verkehrsverein has the subject \\\"Betrifft Schiffahrt Basel-Rheinfelden.\\\"\\n\\n But the cover letter doesn't have a specific title field.\\n\\n I think the safest approach is to treat the cover letter as the main letter:\\n - letter_title: null (or perhaps \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" based on the content, but that's the subject of the enclosed letter)\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"] (or if I can read the signature, that person's name)\\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n But looking at the signature more carefully, it might be \\\"Grundig\\\". However, since the letterhead shows the company name, and the signature is not clearly legible, I should probably use the company name.\\n\\n Actually, looking at the third image, at the bottom it says \\\"Hochachtend BASLER RHEINSCHIFFAHRT-AKTIENGESELLSCHAFT\\\" - so the sender is definitely the company.\\n\\n For the receiver, it's \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\"\\n\\n For the date: \\\"Basel, den 2. April 1928\\\" -> 1928-04-02\\n\\n For the title: There is no explicit title on the cover letter. The subject is implied by the content. I should probably set it to null, or perhaps use the subject line from the enclosed letter if that's what this is about. But strictly speaking, the cover letter doesn't have a title.\\n\\n Wait, looking at the second image, the letter from Kur- und Verkehrsverein Rheinfelden is dated \\\"Basel, den 2. April 1928\\\" at the top, but then at the bottom of page 2 it says \\\"Rheinfelden, 2.4.28\\\". This is confusing. Actually, looking at the second image, the header says \\\"Basel, den 2. April 1928\\\" but the recipient is in Rheinfelden. The third image header says \\\"Rheinfelden, 2.4.28\\\". This suggests the letter was written in Rheinfelden.\\n\\n But the cover letter (Image 1) is from Basel.\\n\\n Actually, looking closely at Image 2: The date at the top is \\\"Basel, den 2. April 1928\\\" but the letter is addressed to \\\"Kur- und Verkehrsverein, Rheinfelden\\\". This is odd. Usually, the date is where the letter was written.\\n\\n Image 3 has \\\"Rheinfelden, 2.4.28\\\" at the top.\\n\\n This suggests the letter from Kur- und Verkehrsverein was written in Rheinfelden.\\n\\n But the cover letter (Image 1) is definitely from Basel.\\n\\n So if we're looking at the cover letter:\\n - Sender: Basler Rheinschiffahrt-Aktiengesellschaft\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: null\\n\\n If we're looking at the enclosed letter:\\n - Sender: Kur- und Verkehrsverein Rheinfelden\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" or similar\\n\\n The task says \\\"a series of images constituting a historical letter\\\" (singular). This could mean the cover letter plus its enclosure constitute one document.\\n\\n But the keys ask for sender_persons, receiver_persons, etc. If it's one document, who is the sender? The cover letter sender? Or the enclosed letter sender?\\n\\n Given that Image 1 is the cover letter and Images 2-3 are the enclosure, and the cover letter says \\\"we are sending you a copy of our letter...\\\", the primary document is the cover letter.\\n\\n So:\\n - letter_title: null (no title on the cover letter)\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"] \\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n But wait, the signature on the first image - is that a person's name? It looks like \\\"Grundig\\\" or \\\"Grund\\\". If I can identify it, I should include it. But it's not entirely clear. The letterhead indicates the company.\\n\\n Also, looking at the example, it uses \\\"Lisa Simpson\\\" - a person. But in this case, the sender is a company. Should I list the company name or try to find the individual?\\n\\n The task says \\\"Name(s) of the person(s) who wrote the letter.\\\" If a company wrote it, technically no person is named, but the company is the entity. However, there is a signature. Let me look again.\\n\\n The signature appears to be \\\"Grundig\\\" or possibly \\\"Gruner\\\". It's hard to read. Given the uncertainty, and that the letterhead clearly shows the company name, I should probably use the company name, or if I must use a person, I'd have to guess, which is bad.\\n\\n Actually, looking at the bottom of the first image, the signature is above \\\"Hochachtend\\\" and the company name. The signature looks like it could be \\\"Grundig\\\".\\n\\n But to be safe and accurate, I should probably list the company name as the sender, since that's what's on the letterhead and what's clearly identifiable.\\n\\n However, looking at the third image, the closing is \\\"Hochachtend BASLER RHEINSCHIFFAHRT-AKTIENGESELLSCHAFT\\\" without an individual signature shown (or it's cut off). The first image has a signature.\\n\\n Given the instructions say \\\"Do not use OCR\\\" and \\\"Use the ISO format YYYY-MM-DD for dates\\\", and \\\"If a piece of information is not included in the letter, set the value for the corresponding key to 'null'\\\", I should be careful.\\n\\n For the title: There is no explicit title on the cover letter. The subject is about shipping, but no title is given. So null.\\n\\n For sender: The letterhead says \\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\". The signature is present but illegible. I should use the company name.\\n\\n For date: \\\"Basel, den 2. April 1928\\\" -> 1928-04-02\\n\\n For receiver: \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\"\\n\\n So:\\n {\\n   \\\"letter_title\\\": [null],\\n   \\\"sender_persons\\\": [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"],\\n   \\\"send_date\\\": [\\\"1928-04-02\\\"],\\n   \\\"receiver_persons\\\": [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n }\\n\\n But wait, is \\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\" a person? No, it's a company. The task asks for \\\"person(s)\\\". This is a dilemma. In historical contexts, when a company writes a letter, the company is often listed as the sender. But the task specifically asks for \\\"person(s)\\\".\\n\\n Looking at the signature again... could it be \\\"Grundig\\\"? If I assume that's the name, I could put that. But it's risky.\\n\\n Alternatively, I could interpret \\\"sender_persons\\\" as the entity sending the letter, which would be the company.\\n\\n Or, I could look at the enclosed letter. The enclosed letter is from \\\"Kur- und Verkehrsverein\\\" which is also an organization.\\n\\n Given that both are organizations, and the task asks for persons, but no individual names are clearly legible, I should probably use the organization names, or set to null if strictly interpreting \\\"persons\\\".\\n\\n But the example shows a person. However, the instructions say \\\"If a piece of information is not included in the letter, set the value... to 'null'\\\". The individual person's name is not clearly included (the signature is illegible), but the company name is.\\n\\n I think the best approach is to use the company names as they appear on the letterhead, as they represent the senders.\\n\\n Actually, looking at the first image again, the text \\\"G/M\\\" appears below the company info. This might be initials.\\n\\n And the signature... it looks like it could be \\\"Grundig\\\".\\n\\n But I think for accuracy, I'll use the company names.\\n\\n Wait, I should check if there's any individual name mentioned. In the first image, no individual name is printed, only the company name. The signature is present but not clearly readable as a specific name.\\n\\n So:\\n - letter_title: null\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"]\\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n Or should I include \\\"Basel\\\" in the receiver? The text says \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\" So the name is \\\"Basler Personenschiffahrtsgesellschaft\\\" and the location is Basel. I'll just use the name.\\n\\n One more thing: The second image shows the letter from Kur- und Verkehrsverein Rheinfelden. If the task considers the entire document (cover + enclosure) as one letter, then there are two senders? No, that doesn't make sense. The cover letter is the primary document.\\n\\n Actually, looking at the structure:\\n - Image 1: Cover letter from A to B, enclosing a copy of a letter from C to B.\\n - Image 2: The letter from C to B (page 1)\\n - Image 3: The letter from C to B (page 2)\\n\\n So the \\\"historical letter\\\" could be interpreted as the cover letter, or the enclosed letter, or the whole thing.\\n\\n But the cover letter is the one that physically exists as the outer document. The enclosed letter is a copy.\\n\\n The cover letter is from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n I'll go with that.\\n\\n Final check:\\n - letter_title: No title visible on the cover letter. The subject of the enclosed letter is \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" but that's not the title of the cover letter. So null.\\n - sender_persons: Basler Rheinschiffahrt-Aktiengesellschaft\\n - send_date: 1928-04-02\\n - receiver_persons: Basler Personenschiffahrtsgesellschaft\\n\\n Actually, looking at the first image, the receiver is written as:\\n \\\"Basler Personenschiffahrtsgesellschaft,\\n Basel.\\\"\\n\\n So that's clear.\\n\\n The date is \\\"Basel, den 2. April 1928.\\\" -> 1928-04-02.\\n\\n The sender is the company whose letterhead is used.\\n\\n I think that's the correct extraction.\",\"reasoning_details\":[{\"type\":\"reasoning.text\",\"text\":\"The user wants me to extract specific information from a historical letter and return it in JSON format. The letter is in German and appears to be from 1928.\\n\\n Let me analyze the images:\\n\\n 1. First image (cover letter):\\n    - Date: Basel, den 2. April 1928\\n    - Sender: Basler Rheinschiffahrt-Aktiengesellschaft (Basel Rhine Shipping Company)\\n    - Receiver: Basler Personenschiffahrtsgesellschaft, Basel\\n    - Content: Sending a copy of a letter to Kur- und Verkehrsverein Rheinfelden regarding shipping between Basel and Rheinfelden\\n    - Signature: There's a signature, but it's not clearly legible as a specific person's name. It looks like \\\"Grundig\\\" or similar, but the letterhead shows the company name.\\n\\n 2. Second image (first page of the letter):\\n    - Date: Basel, den 2. April 1928\\n    - To: BASLER PERSONENSCHIFFFAHRTSGESELLSCHAFT\\n    - From: Kur- und Verkehrsverein, Rheinfelden\\n    - Subject: Betrifft Schiffahrt Basel-Rheinfelden (Concerning shipping Basel-Rheinfelden)\\n    - This appears to be the letter being referenced in the cover letter.\\n\\n 3. Third image (continuation):\\n    - Date: Rheinfelden, 2.4.28\\n    - Continuation of the letter from Kur- und Verkehrsverein to Basler Personenschiffahrtsgesellschaft\\n\\n Wait, I need to be careful here. The first image is a cover letter from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft, enclosing a copy of a letter.\\n\\n The second and third images appear to be the actual letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft, dated April 2, 1928.\\n\\n But the task asks for the letter title, sender, date, and receiver. Which letter? The cover letter or the enclosed letter?\\n\\n Looking at the first image, it's a cover letter from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n The second image shows the letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft.\\n\\n Actually, looking more carefully:\\n - Image 1: Cover letter from Basler Rheinschiffahrt-Aktiengesellschaft (sender) to Basler Personenschiffahrtsgesellschaft (receiver), dated 2. April 1928.\\n - Image 2: The enclosed letter from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft, also dated 2. April 1928.\\n - Image 3: Continuation of the enclosed letter.\\n\\n The task says \\\"You are presented with a series of images constituting a historical letter.\\\" This suggests all images together constitute one letter/document.\\n\\n The cover letter (Image 1) is from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n The enclosed letter (Images 2-3) is from Kur- und Verkehrsverein Rheinfelden to Basler Personenschiffahrtsgesellschaft.\\n\\n But the cover letter is the outer letter. The task likely refers to the cover letter as the main letter, or possibly the entire correspondence.\\n\\n Let me look at the keys:\\n - letter_title: Title of the letter.\\n - sender_persons: Name(s) of the person(s) who wrote the letter.\\n - send_date: The exact or approximate date the letter was written.\\n - receiver_persons: Name(s) of the person(s) who received the letter.\\n\\n For the cover letter (Image 1):\\n - Sender: Basler Rheinschiffahrt-Aktiengesellschaft (this is a company, not a person, but the task asks for \\\"person(s)\\\")\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: There's no explicit title, but the content mentions sending a copy of a letter. The subject is about shipping between Basel and Rheinfelden.\\n\\n For the enclosed letter (Images 2-3):\\n - Sender: Kur- und Verkehrsverein Rheinfelden (also an organization)\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Subject: Betrifft Schiffahrt Basel-Rheinfelden\\n\\n Since the first image is the cover letter and the others are enclosures, and the task mentions \\\"a historical letter\\\" (singular), I should probably focus on the cover letter, or treat the whole thing as one document.\\n\\n However, looking at the signature on the first image, it appears to be signed by an individual, though the name is hard to read. It looks like it could be \\\"Grundig\\\" or similar.\\n\\n Actually, looking at the letterhead on the first image:\\n - Basler Rheinschiffahrt-Aktiengesellschaft\\n - Marktgasse 5\\n - Various contact details\\n\\n The signature appears to be \\\"Grundig\\\" or \\\"Grund\\\" with a flourish.\\n\\n But the task asks for \\\"sender_persons\\\" - if it's a company, should I list the company name or the individual? The example shows \\\"Lisa Simpson\\\" as a person. But in historical documents, often the company name is used.\\n\\n Let me reconsider. The first image is clearly a cover letter. The text says: \\\"In der Beilage senden wir Ihnen Kopie unseres heutigen Schreibens an den Kur- und Verkehrsverein Rheinfelden zur gefl. Kenntnisnahme.\\\"\\n\\n So the sender is Basler Rheinschiffahrt-Aktiengesellschaft.\\n The receiver is Basler Personenschiffahrtsgesellschaft.\\n The date is 2. April 1928.\\n\\n For the title, there isn't really a title, but the subject matter is about the shipping route Basel-Rheinfelden.\\n\\n Wait, looking at the second image, the letter from Kur- und Verkehrsverein has the subject \\\"Betrifft Schiffahrt Basel-Rheinfelden.\\\"\\n\\n But the cover letter doesn't have a specific title field.\\n\\n I think the safest approach is to treat the cover letter as the main letter:\\n - letter_title: null (or perhaps \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" based on the content, but that's the subject of the enclosed letter)\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"] (or if I can read the signature, that person's name)\\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n But looking at the signature more carefully, it might be \\\"Grundig\\\". However, since the letterhead shows the company name, and the signature is not clearly legible, I should probably use the company name.\\n\\n Actually, looking at the third image, at the bottom it says \\\"Hochachtend BASLER RHEINSCHIFFAHRT-AKTIENGESELLSCHAFT\\\" - so the sender is definitely the company.\\n\\n For the receiver, it's \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\"\\n\\n For the date: \\\"Basel, den 2. April 1928\\\" -> 1928-04-02\\n\\n For the title: There is no explicit title on the cover letter. The subject is implied by the content. I should probably set it to null, or perhaps use the subject line from the enclosed letter if that's what this is about. But strictly speaking, the cover letter doesn't have a title.\\n\\n Wait, looking at the second image, the letter from Kur- und Verkehrsverein Rheinfelden is dated \\\"Basel, den 2. April 1928\\\" at the top, but then at the bottom of page 2 it says \\\"Rheinfelden, 2.4.28\\\". This is confusing. Actually, looking at the second image, the header says \\\"Basel, den 2. April 1928\\\" but the recipient is in Rheinfelden. The third image header says \\\"Rheinfelden, 2.4.28\\\". This suggests the letter was written in Rheinfelden.\\n\\n But the cover letter (Image 1) is from Basel.\\n\\n Actually, looking closely at Image 2: The date at the top is \\\"Basel, den 2. April 1928\\\" but the letter is addressed to \\\"Kur- und Verkehrsverein, Rheinfelden\\\". This is odd. Usually, the date is where the letter was written.\\n\\n Image 3 has \\\"Rheinfelden, 2.4.28\\\" at the top.\\n\\n This suggests the letter from Kur- und Verkehrsverein was written in Rheinfelden.\\n\\n But the cover letter (Image 1) is definitely from Basel.\\n\\n So if we're looking at the cover letter:\\n - Sender: Basler Rheinschiffahrt-Aktiengesellschaft\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: null\\n\\n If we're looking at the enclosed letter:\\n - Sender: Kur- und Verkehrsverein Rheinfelden\\n - Receiver: Basler Personenschiffahrtsgesellschaft\\n - Date: 1928-04-02\\n - Title: \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" or similar\\n\\n The task says \\\"a series of images constituting a historical letter\\\" (singular). This could mean the cover letter plus its enclosure constitute one document.\\n\\n But the keys ask for sender_persons, receiver_persons, etc. If it's one document, who is the sender? The cover letter sender? Or the enclosed letter sender?\\n\\n Given that Image 1 is the cover letter and Images 2-3 are the enclosure, and the cover letter says \\\"we are sending you a copy of our letter...\\\", the primary document is the cover letter.\\n\\n So:\\n - letter_title: null (no title on the cover letter)\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"] \\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n But wait, the signature on the first image - is that a person's name? It looks like \\\"Grundig\\\" or \\\"Grund\\\". If I can identify it, I should include it. But it's not entirely clear. The letterhead indicates the company.\\n\\n Also, looking at the example, it uses \\\"Lisa Simpson\\\" - a person. But in this case, the sender is a company. Should I list the company name or try to find the individual?\\n\\n The task says \\\"Name(s) of the person(s) who wrote the letter.\\\" If a company wrote it, technically no person is named, but the company is the entity. However, there is a signature. Let me look again.\\n\\n The signature appears to be \\\"Grundig\\\" or possibly \\\"Gruner\\\". It's hard to read. Given the uncertainty, and that the letterhead clearly shows the company name, I should probably use the company name, or if I must use a person, I'd have to guess, which is bad.\\n\\n Actually, looking at the bottom of the first image, the signature is above \\\"Hochachtend\\\" and the company name. The signature looks like it could be \\\"Grundig\\\".\\n\\n But to be safe and accurate, I should probably list the company name as the sender, since that's what's on the letterhead and what's clearly identifiable.\\n\\n However, looking at the third image, the closing is \\\"Hochachtend BASLER RHEINSCHIFFAHRT-AKTIENGESELLSCHAFT\\\" without an individual signature shown (or it's cut off). The first image has a signature.\\n\\n Given the instructions say \\\"Do not use OCR\\\" and \\\"Use the ISO format YYYY-MM-DD for dates\\\", and \\\"If a piece of information is not included in the letter, set the value for the corresponding key to 'null'\\\", I should be careful.\\n\\n For the title: There is no explicit title on the cover letter. The subject is about shipping, but no title is given. So null.\\n\\n For sender: The letterhead says \\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\". The signature is present but illegible. I should use the company name.\\n\\n For date: \\\"Basel, den 2. April 1928\\\" -> 1928-04-02\\n\\n For receiver: \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\"\\n\\n So:\\n {\\n   \\\"letter_title\\\": [null],\\n   \\\"sender_persons\\\": [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"],\\n   \\\"send_date\\\": [\\\"1928-04-02\\\"],\\n   \\\"receiver_persons\\\": [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n }\\n\\n But wait, is \\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\" a person? No, it's a company. The task asks for \\\"person(s)\\\". This is a dilemma. In historical contexts, when a company writes a letter, the company is often listed as the sender. But the task specifically asks for \\\"person(s)\\\".\\n\\n Looking at the signature again... could it be \\\"Grundig\\\"? If I assume that's the name, I could put that. But it's risky.\\n\\n Alternatively, I could interpret \\\"sender_persons\\\" as the entity sending the letter, which would be the company.\\n\\n Or, I could look at the enclosed letter. The enclosed letter is from \\\"Kur- und Verkehrsverein\\\" which is also an organization.\\n\\n Given that both are organizations, and the task asks for persons, but no individual names are clearly legible, I should probably use the organization names, or set to null if strictly interpreting \\\"persons\\\".\\n\\n But the example shows a person. However, the instructions say \\\"If a piece of information is not included in the letter, set the value... to 'null'\\\". The individual person's name is not clearly included (the signature is illegible), but the company name is.\\n\\n I think the best approach is to use the company names as they appear on the letterhead, as they represent the senders.\\n\\n Actually, looking at the first image again, the text \\\"G/M\\\" appears below the company info. This might be initials.\\n\\n And the signature... it looks like it could be \\\"Grundig\\\".\\n\\n But I think for accuracy, I'll use the company names.\\n\\n Wait, I should check if there's any individual name mentioned. In the first image, no individual name is printed, only the company name. The signature is present but not clearly readable as a specific name.\\n\\n So:\\n - letter_title: null\\n - sender_persons: [\\\"Basler Rheinschiffahrt-Aktiengesellschaft\\\"]\\n - send_date: [\\\"1928-04-02\\\"]\\n - receiver_persons: [\\\"Basler Personenschiffahrtsgesellschaft\\\"]\\n\\n Or should I include \\\"Basel\\\" in the receiver? The text says \\\"Basler Personenschiffahrtsgesellschaft, Basel.\\\" So the name is \\\"Basler Personenschiffahrtsgesellschaft\\\" and the location is Basel. I'll just use the name.\\n\\n One more thing: The second image shows the letter from Kur- und Verkehrsverein Rheinfelden. If the task considers the entire document (cover + enclosure) as one letter, then there are two senders? No, that doesn't make sense. The cover letter is the primary document.\\n\\n Actually, looking at the structure:\\n - Image 1: Cover letter from A to B, enclosing a copy of a letter from C to B.\\n - Image 2: The letter from C to B (page 1)\\n - Image 3: The letter from C to B (page 2)\\n\\n So the \\\"historical letter\\\" could be interpreted as the cover letter, or the enclosed letter, or the whole thing.\\n\\n But the cover letter is the one that physically exists as the outer document. The enclosed letter is a copy.\\n\\n The cover letter is from Basler Rheinschiffahrt-Aktiengesellschaft to Basler Personenschiffahrtsgesellschaft.\\n\\n I'll go with that.\\n\\n Final check:\\n - letter_title: No title visible on the cover letter. The subject of the enclosed letter is \\\"Betrifft Schiffahrt Basel-Rheinfelden\\\" but that's not the title of the cover letter. So null.\\n - sender_persons: Basler Rheinschiffahrt-Aktiengesellschaft\\n - send_date: 1928-04-02\\n - receiver_persons: Basler Personenschiffahrtsgesellschaft\\n\\n Actually, looking at the first image, the receiver is written as:\\n \\\"Basler Personenschiffahrtsgesellschaft,\\n Basel.\\\"\\n\\n So that's clear.\\n\\n The date is \\\"Basel, den 2. April 1928.\\\" -> 1928-04-02.\\n\\n The sender is the company whose letterhead is used.\\n\\n I think that's the correct extraction.\",\"format\":\"unknown\",\"index\":0}]},\"native_finish_reason\":\"stop\"}],\"created\":1780657774,\"model\":\"stepfun/step-3.7-flash-20260528\",\"object\":\"chat.completion\",\"service_tier\":null,\"system_fingerprint\":null,\"usage\":{\"completion_tokens\":3694,\"prompt_tokens\":5013,\"total_tokens\":8707,\"completion_tokens_details\":{\"accepted_prediction_tokens\":null,\"audio_tokens\":0,\"reasoning_tokens\":0,\"rejected_prediction_tokens\":null,\"image_tokens\":0},\"prompt_tokens_details\":{\"audio_tokens\":0,\"cached_tokens\":0,\"cache_write_tokens\":0,\"video_tokens\":0},\"cost\":0.0052507,\"is_byok\":false,\"cost_details\":{\"upstream_inference_cost\":0.0052507,\"upstream_inference_prompt_cost\":0.0010026,\"upstream_inference_completions_cost\":0.0042481}},\"provider\":\"StepFun\"}"}, "scoring": {"f1_macro": 0.56, "f1_micro": 0.56, "cost_summary": {"total_input_tokens": 129133, "total_output_tokens": 164779, "total_tokens": 293912, "input_cost_usd": 0.02582660000000002, "output_cost_usd": 0.18949585000000002, "total_cost_usd": 0.21532244999999997}}, "normalized_score": 56.00000000000001}