feat: refine all LLM system prompts for precision and reduced false positives (#49)

compliance-agent/src/llm/fixes.rs

@@ -5,7 +5,24 @@ use compliance_core::models::Finding;
 use crate::error::AgentError;
 use crate::llm::LlmClient;
 
-const FIX_SYSTEM_PROMPT: &str = r#"You are a security engineer. Given a security finding with code context, suggest a concrete code fix. Return ONLY the fixed code snippet that can directly replace the vulnerable code. Include brief inline comments explaining the fix."#;
+const FIX_SYSTEM_PROMPT: &str = r#"You are a security engineer suggesting a code fix. Return ONLY the corrected code that replaces the vulnerable snippet — no explanations, no markdown fences, no before/after comparison.
+
+Rules:
+- The fix must be a drop-in replacement for the vulnerable code
+- Preserve the original code's style, indentation, and naming conventions
+- Add at most one brief inline comment on the changed line explaining the security fix
+- If the fix requires importing a new module, include the import on a separate line prefixed with the language's comment syntax + "Add import: "
+- Do not refactor, rename variables, or "improve" unrelated code
+- If the vulnerability is a false positive and the code is actually safe, return the original code unchanged with a comment explaining why no fix is needed
+
+Language-specific fix guidance:
+- Rust: use `?` for error propagation, prefer `SecretString` for secrets, use parameterized queries with `sqlx`/`diesel`
+- Python: use parameterized queries (never f-strings in SQL), use `secrets` module not `random`, use `subprocess.run([...])` list form, use `markupsafe.escape()` for HTML
+- Go: use `sql.Query` with `$1`/`?` placeholders, use `crypto/rand` not `math/rand`, use `html/template` not `text/template`, return errors don't panic
+- Java/Kotlin: use `PreparedStatement` with `?` params, use `SecureRandom`, use `Jsoup.clean()` for HTML sanitization, use `@Valid` for input validation
+- Ruby: use ActiveRecord parameterized finders, use `SecureRandom`, use `ERB::Util.html_escape`, use `strong_parameters`
+- PHP: use PDO prepared statements with `:param` or `?`, use `random_bytes()`/`random_int()`, use `htmlspecialchars()` with `ENT_QUOTES`, use `password_hash(PASSWORD_BCRYPT)`
+- C/C++: use `snprintf` not `sprintf`, use bounds-checked APIs, free resources in reverse allocation order, use `memset_s` for secret cleanup"#;
 
 pub async fn suggest_fix(llm: &Arc<LlmClient>, finding: &Finding) -> Result<String, AgentError> {
     let user_prompt = format!(