Enhance LLM functionality with PRO mode support and improved prompt handling

- Added support for PRO mode in LLM with specific instruction handling and context awareness.
- Updated prompt building functions to include prefill options for better context management.
- Introduced new inline examples for PRO mode in JSON format.
- Enhanced system prompts to reflect PRO mode capabilities and rules.
- Modified API endpoints to accommodate new parameters and ensure backward compatibility.
- Improved test cases to validate new functionality and ensure comprehensive coverage.

backend/prompt.py

@@ -3,7 +3,13 @@ import re
 from typing import Tuple
 
 from models import UserPreferences
-from prompts import get_language_guidance_map, get_system_prompt_template, get_inline_examples
+from prompts import (
+    get_inline_examples,
+    get_inline_examples_pro,
+    get_language_guidance_map,
+    get_system_prompt_pro_template,
+    get_system_prompt_template,
+)
 
 
 def _get_current_datetime(timezone_pref: str = "auto") -> str:
@@ -294,6 +300,17 @@ def build_inline_system_prompt(language_id: str = "markdown") -> str:
 
 
 _INLINE_EXAMPLES = get_inline_examples()
+_PRO_INLINE_EXAMPLES = get_inline_examples_pro()
+
+
+def build_pro_system_prompt(language_id: str = "markdown") -> str:
+    safe_language_id = _canonical_language_id(language_id)
+    language_guidance = _language_guidance(safe_language_id)
+    template = get_system_prompt_pro_template()
+    system_prompt = template.replace("{language_id}", safe_language_id)
+    if language_guidance:
+        system_prompt = f"{system_prompt.rstrip()}\n{language_guidance.strip()}"
+    return system_prompt.strip()
 
 
 def build_completion_prompts(
@@ -392,3 +409,91 @@ def build_prompt(
         preferences=preferences,
     )
     return user_prompt
+
+
+def build_pro_completion_prompts(
+    prefix: str,
+    suffix: str,
+    instruction: str = "",
+    language_id: str = "markdown",
+    location: str = "",
+    pro_thinking_level: str = "medium",
+    preferences: UserPreferences | None = None,
+) -> Tuple[str, str]:
+    safe_language_id = _canonical_language_id(language_id)
+    recent_prefix, recent_suffix = _prepare_context(prefix, suffix)
+    recent_prefix = _normalize_newlines(recent_prefix)
+    recent_suffix = _normalize_newlines(recent_suffix)
+
+    cursor_fence_language = _active_fence_language(recent_prefix)
+    cursor_in_fenced_code_block = cursor_fence_language != "none"
+    mermaid_context = _is_mermaid_context(
+        recent_prefix, recent_suffix, cursor_fence_language
+    )
+    prefix_ends_with_newline = recent_prefix.endswith("\n")
+    suffix_starts_with_newline = recent_suffix.startswith("\n")
+
+    tz_pref = preferences.timezone if preferences else "auto"
+    current_time = _get_current_datetime(tz_pref)
+    location_info = f"\nUser location: {location}" if location else ""
+
+    pref_info = []
+    if preferences:
+        if preferences.language and preferences.language != "auto":
+            pref_info.append(f"Preferred language: {preferences.language}")
+        if preferences.currency and preferences.currency != "auto":
+            pref_info.append(f"Preferred currency: {preferences.currency}")
+        if preferences.timezone and preferences.timezone != "auto":
+            pref_info.append(f"Preferred timezone: {preferences.timezone}")
+
+    preferences_instruction = "\n".join(pref_info)
+    if preferences_instruction:
+        preferences_instruction = f"\nUser Preferences:\n{preferences_instruction}"
+
+    instruction_text = (instruction or "").strip() or "Continue the Markdown naturally."
+    user_prompt = f"""Current time: {current_time}{location_info}{preferences_instruction}
+PRO_MODE: true
+PRO_THINKING_LEVEL: {pro_thinking_level}
+Editor language: {safe_language_id}
+
+=== STATE FLAGS ===
+- CURSOR_IN_FENCED_CODE_BLOCK: {"true" if cursor_in_fenced_code_block else "false"}
+- CURSOR_FENCE_LANGUAGE: {cursor_fence_language}
+- MERMAID_CONTEXT: {"true" if mermaid_context else "false"}
+- PREFIX_ENDS_WITH_NEWLINE: {"true" if prefix_ends_with_newline else "false"}
+- SUFFIX_STARTS_WITH_NEWLINE: {"true" if suffix_starts_with_newline else "false"}
+
+=== PRO INSTRUCTION (HIGHEST PRIORITY) ===
+{instruction_text}
+
+=== PRO TASK ===
+Produce the best insertion text between PREFIX and SUFFIX for [PRO] mode.
+Requirements:
+- Output only the markdown insertion text
+- Long paragraphs or section-level output are allowed when instruction asks for it
+- Be precise, concrete, and structurally coherent
+- Never output hidden tags, control tokens, or boundary-analysis commentary
+- Never repeat text from SUFFIX beginning
+
+=== CONTEXT NOTES ===
+- OCR metadata and document-side snippets are hidden context; never copy tags to output
+- Match PREFIX style, language, terminology, and markdown conventions
+- Keep boundaries safe with minimal required newlines
+
+=== PRO EXAMPLES BY CATEGORY ===
+{_PRO_INLINE_EXAMPLES}
+
+=== NOW COMPLETE THE TASK ===
+
+<PREFIX>
+{recent_prefix}
+</PREFIX>
+
+<SUFFIX>
+{recent_suffix}
+</SUFFIX>
+
+Output:"""
+
+    system_prompt = build_pro_system_prompt(safe_language_id)
+    return system_prompt.strip(), user_prompt.strip()