Add default system prompt for gpt-oss models to discourage table output

pcrDev.json

@@ -1,6 +1,6 @@
 {
   "HashAlgorithm": "Sha384 { ... }",
-  "PCR0": "fdc4951ee70183c9f0c7026b81eb0137394c6574e37d985122c1ef5494161dc5aa63f7bbd0b6f2e70e125e8b5458956d",
+  "PCR0": "5d7a9d7ca6d06831f1f775a964db5e702e4e506c6aa7dfeeac2bb061b8ef3867a33e0e3a2b0bd51c8d2be0ed9e44072c",
   "PCR1": "f004075c672258b499f8e88d59701031a3b451f65c7de60c81d09da2b0799272675481ec390527594dd7069cb7de59d7",
-  "PCR2": "5dba95979634d14bb13c8db247c104a8c1c82e7d700e58927a25231bb087b5ff104c97632ad526bd44de8f60cdf706c7"
+  "PCR2": "be47ba57251142fba5329e8cba203d5d09964a1e44ca36765c67711e567126a4052c8bb21fa2c2a52885fac11740233d"
 }

pcrDevHistory.json

@@ -551,5 +551,12 @@
     "PCR2": "5dba95979634d14bb13c8db247c104a8c1c82e7d700e58927a25231bb087b5ff104c97632ad526bd44de8f60cdf706c7",
     "timestamp": 1772503491,
     "signature": "LBrtuXh0jMDQDWOsrQdNyONNLq8aVoZTVgpmz4ud4qOoj1F50eJH5F/NCSpOohDkdsP9epEde9pq5IbXXXmrFzsfzE6jvs5vLfvT0jEb8hvXk39TwaaFPpNReWq9wGgl"
+  },
+  {
+    "PCR0": "5d7a9d7ca6d06831f1f775a964db5e702e4e506c6aa7dfeeac2bb061b8ef3867a33e0e3a2b0bd51c8d2be0ed9e44072c",
+    "PCR1": "f004075c672258b499f8e88d59701031a3b451f65c7de60c81d09da2b0799272675481ec390527594dd7069cb7de59d7",
+    "PCR2": "be47ba57251142fba5329e8cba203d5d09964a1e44ca36765c67711e567126a4052c8bb21fa2c2a52885fac11740233d",
+    "timestamp": 1772686625,
+    "signature": "nbI0TO6gz2gBCbSYQKrZCdYGhjhuRIWO+Rt6rIEtZOBQHUMleb3kpx4ozl/d0nW9rxuccWj69tsCHB5eqatkItor2IkVjp5DyyWZ//1QHAPgdWxCcuYEW8UO3xlKqbWC"
   }
 ]

pcrProd.json

@@ -1,6 +1,6 @@
 {
   "HashAlgorithm": "Sha384 { ... }",
-  "PCR0": "ed0d2016c01ae9aa4612de6b910cb1b80b9beccb4cdb5194cbe63c5b40bb364c33491811376abfaec91b90b1daa9cb77",
+  "PCR0": "d7ff34da2a1b02a67e49d2de8ace4d4da90b45fc3367d57975aad0a71269945985f9c09c273bf88ee0726ad788e50a20",
   "PCR1": "f004075c672258b499f8e88d59701031a3b451f65c7de60c81d09da2b0799272675481ec390527594dd7069cb7de59d7",
-  "PCR2": "a6acf1874b640281d65176a186f9f389b7f141970d9bec0075877ec4067d0d814b55f869e094b20e906896e1ef6e055b"
+  "PCR2": "7e8a97778ed06f6d8f677c18116feb8f32d301a57c5cd676bb5fe4003d842493930aab3bd6625b4645769dc7a845d61f"
 }

pcrProdHistory.json

@@ -551,5 +551,12 @@
     "PCR2": "a6acf1874b640281d65176a186f9f389b7f141970d9bec0075877ec4067d0d814b55f869e094b20e906896e1ef6e055b",
     "timestamp": 1772503533,
     "signature": "/dSYWuHMLW7GAqNGCFggie5wpHiKPNFAjEhQaLbqmAFkNv5lG3H+qaG3iapLXHpsHCnKjZRmil/0Uq44n5QGJI63T54QOLAoTyHGftDAKaUBD0DueAHCVqj1i4u/kSpu"
+  },
+  {
+    "PCR0": "d7ff34da2a1b02a67e49d2de8ace4d4da90b45fc3367d57975aad0a71269945985f9c09c273bf88ee0726ad788e50a20",
+    "PCR1": "f004075c672258b499f8e88d59701031a3b451f65c7de60c81d09da2b0799272675481ec390527594dd7069cb7de59d7",
+    "PCR2": "7e8a97778ed06f6d8f677c18116feb8f32d301a57c5cd676bb5fe4003d842493930aab3bd6625b4645769dc7a845d61f",
+    "timestamp": 1772686654,
+    "signature": "JG7jtCk8JsSbR4OWL7wF7cHAhyBM8cJ/tp5BNjFKdi0qYiXV0T7ady/tjzGNGer5mhNKxM8/Cmf+X7P7mnfnsFOyaoW3wB8f94XOvrGFlb703ou35BePosMO6db802FP"
   }
 ]

src/web/responses/context_builder.rs

@@ -5,9 +5,16 @@ use crate::encrypt::decrypt_with_key;
 use crate::tokens::{count_tokens, model_max_ctx};
 use crate::DBConnection;
 use serde_json::json;
-use tracing::error;
+use tracing::{debug, error};
 use uuid::Uuid;
 
+/// Default system prompt for gpt-oss models when no user-defined system prompt is set.
+/// This model tends to produce excessive tables even for simple questions, so we
+/// instruct it to avoid tables unless the user explicitly asks for them.
+const GPT_OSS_DEFAULT_SYSTEM_PROMPT: &str =
+    "Do not format your responses as tables unless the user explicitly asks for a table. \
+    Prefer clear, concise prose or lists when presenting information.";
+
 #[derive(Debug, Clone)]
 pub struct ChatMsg {
     pub role: &'static str,
@@ -46,6 +53,14 @@ pub fn build_prompt<D: DBConnection + ?Sized>(
         let tok = default_instruction.prompt_tokens as usize;
         system_tokens = tok;
         Some((ROLE_SYSTEM, content, tok))
+    } else if model.starts_with("gpt-oss") {
+        // For gpt-oss models, inject a default system prompt to discourage excessive table usage
+        debug!(
+            "No user instructions set for gpt-oss model, using default anti-table system prompt"
+        );
+        let tok = count_tokens(GPT_OSS_DEFAULT_SYSTEM_PROMPT);
+        system_tokens = tok;
+        Some((ROLE_SYSTEM, GPT_OSS_DEFAULT_SYSTEM_PROMPT.to_string(), tok))
     } else {
         None
     };