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fix: detect incomplete Anthropic SSE stream and deduplicate system prompt #26

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fix: detect incomplete Anthropic SSE stream and deduplicate system prompt #26

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51 changes: 24 additions & 27 deletions src-tauri/src/services/chat_service.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,16 @@ use crate::{

use super::{now_rfc3339, provider_service};

const CHAT_SYSTEM_INSTRUCTIONS: &str = concat!(
"IMPORTANT: Reply using the same language as the user's latest message. If user writes Indonesian, answer in Indonesian. Never switch to another language unless the user explicitly asks you to.\n\n",
"INTERACTIVE PREVIEW: When the user asks for a visualization, diagram, chart, interactive demo, or any visual HTML content, output it as a fenced code block with tag `html:preview`. The app renders it as a live iframe preview with a full design system pre-loaded (CSS variables, SVG color ramp classes, pre-styled form elements, light/dark mode).\n\n",
"Design rules: flat (no gradients/shadows/glow), use CSS vars for colors (var(--color-text-primary), var(--color-background-secondary), etc). system-ui font, 2 weights (400/500), sentence case. Structure: style → content → script last.\n\n",
"SVG diagrams: use pre-loaded classes — `.t` (14px text), `.ts` (12px), `.th` (14px bold), `.box` (neutral), `.node` (clickable), `.arr` (arrow), `.leader` (dashed). Color ramps: `class=\"c-blue\"` on `<g>` wrapping shape+text — auto light/dark. Available: c-purple, c-teal, c-coral, c-blue, c-amber, c-green, c-red, c-gray, c-pink. Max 2-3 ramps per diagram.\n\n",
"Chart.js: wrap canvas in div with position:relative + explicit height. Load UMD from cdnjs.cloudflare.com with onload callback. Disable default legend, build custom HTML legend with 10px colored squares.\n\n",
"Interactive: form elements pre-styled. Use sendPrompt(text) for drill-down. CDN: cdnjs.cloudflare.com, cdn.jsdelivr.net, unpkg.com, esm.sh only.\n\n",
"Always output COMPLETE standalone HTML (DOCTYPE, html, head, body). No titles/prose inside widget — explanations go in your response text."
);

pub async fn get_messages(db: &SqlitePool, session_id: &str) -> AppResult<Vec<Message>> {
let messages = sqlx::query_as::<_, Message>(
"SELECT id, session_id, role, content, created_at FROM messages \
Expand Down Expand Up @@ -180,22 +190,13 @@ async fn send_openai_compatible(
"stream": true,
});

let system_instructions = concat!(
"IMPORTANT: Reply using the same language as the user's latest message. If user writes Indonesian, answer in Indonesian. Never switch to another language unless the user explicitly asks you to.\n\n",
"INTERACTIVE PREVIEW: When the user asks for a visualization, diagram, chart, interactive demo, or any visual HTML content, output it as a fenced code block with tag `html:preview`. The app renders it as a live iframe preview with a full design system pre-loaded (CSS variables, SVG color ramp classes, pre-styled form elements, light/dark mode).\n\n",
"Design rules: flat (no gradients/shadows/glow), use CSS vars for colors (var(--color-text-primary), var(--color-background-secondary), etc). system-ui font, 2 weights (400/500), sentence case. Structure: style → content → script last.\n\n",
"SVG diagrams: use pre-loaded classes — `.t` (14px text), `.ts` (12px), `.th` (14px bold), `.box` (neutral), `.node` (clickable), `.arr` (arrow), `.leader` (dashed). Color ramps: `class=\"c-blue\"` on `<g>` wrapping shape+text — auto light/dark. Available: c-purple, c-teal, c-coral, c-blue, c-amber, c-green, c-red, c-gray, c-pink. Max 2-3 ramps per diagram.\n\n",
"Chart.js: wrap canvas in div with position:relative + explicit height. Load UMD from cdnjs.cloudflare.com with onload callback. Disable default legend, build custom HTML legend with 10px colored squares.\n\n",
"Interactive: form elements pre-styled. Use sendPrompt(text) for drill-down. CDN: cdnjs.cloudflare.com, cdn.jsdelivr.net, unpkg.com, esm.sh only.\n\n",
"Always output COMPLETE standalone HTML (DOCTYPE, html, head, body). No titles/prose inside widget — explanations go in your response text."
);
let payload_with_system = if let Some(arr) = payload.get("messages").and_then(Value::as_array) {
let mut updated = arr.clone();
updated.insert(
0,
serde_json::json!({
"role": "system",
"content": system_instructions,
"content": CHAT_SYSTEM_INSTRUCTIONS,
}),
);
let mut p = payload.clone();
Expand Down Expand Up @@ -250,19 +251,10 @@ async fn send_anthropic(
"stream": true,
});

let system_instructions_anthropic = concat!(
"IMPORTANT: Reply using the same language as the user's latest message. If user writes Indonesian, answer in Indonesian. Never switch to another language unless the user explicitly asks you to.\n\n",
"INTERACTIVE PREVIEW: When the user asks for a visualization, diagram, chart, interactive demo, or any visual HTML content, output it as a fenced code block with tag `html:preview`. The app renders it as a live iframe preview with a full design system pre-loaded (CSS variables, SVG color ramp classes, pre-styled form elements, light/dark mode).\n\n",
"Design rules: flat (no gradients/shadows/glow), use CSS vars for colors (var(--color-text-primary), var(--color-background-secondary), etc). system-ui font, 2 weights (400/500), sentence case. Structure: style → content → script last.\n\n",
"SVG diagrams: use pre-loaded classes — `.t` (14px text), `.ts` (12px), `.th` (14px bold), `.box` (neutral), `.node` (clickable), `.arr` (arrow), `.leader` (dashed). Color ramps: `class=\"c-blue\"` on `<g>` wrapping shape+text — auto light/dark. Available: c-purple, c-teal, c-coral, c-blue, c-amber, c-green, c-red, c-gray, c-pink. Max 2-3 ramps per diagram.\n\n",
"Chart.js: wrap canvas in div with position:relative + explicit height. Load UMD from cdnjs.cloudflare.com with onload callback. Disable default legend, build custom HTML legend with 10px colored squares.\n\n",
"Interactive: form elements pre-styled. Use sendPrompt(text) for drill-down. CDN: cdnjs.cloudflare.com, cdn.jsdelivr.net, unpkg.com, esm.sh only.\n\n",
"Always output COMPLETE standalone HTML (DOCTYPE, html, head, body). No titles/prose inside widget — explanations go in your response text."
);
if let Some(sys) = system_msgs.first() {
payload["system"] = serde_json::json!(format!("{}\n\n{}", sys.content, system_instructions_anthropic));
payload["system"] = serde_json::json!(format!("{}\n\n{}", sys.content, CHAT_SYSTEM_INSTRUCTIONS));
} else {
payload["system"] = serde_json::json!(system_instructions_anthropic);
payload["system"] = serde_json::json!(CHAT_SYSTEM_INSTRUCTIONS);
}

let mut request = client
Expand Down Expand Up @@ -372,8 +364,9 @@ async fn stream_anthropic_sse(
let mut stream = response.bytes_stream();
let mut line_buffer = String::new();
let mut output = String::new();
let mut message_stop_received = false;

loop {
'outer: loop {
tokio::select! {
_ = cancel_token.cancelled() => {
return Err(AppError::Cancelled);
Expand All @@ -391,7 +384,8 @@ async fn stream_anthropic_sse(
}

if parse_anthropic_sse_line(&line, on_token, &mut output)? {
return Ok(output);
message_stop_received = true;
break 'outer;
}
}
}
Expand All @@ -402,6 +396,12 @@ async fn stream_anthropic_sse(
}
}

if !message_stop_received {
return Err(AppError::Http(
"Stream ended without completion signal — connection may have been interrupted. Please retry.".to_string(),
));
}

Ok(output)
}

Expand All @@ -428,10 +428,7 @@ fn parse_anthropic_sse_line(
};
let payload = payload.trim();

let value: Value = match serde_json::from_str(payload) {
Ok(v) => v,
Err(_) => return Ok(false),
};
let value: Value = serde_json::from_str(payload)?;

let event_type = value.get("type").and_then(Value::as_str).unwrap_or("");

Expand Down